# A Very Compact Hybrid Amp



## runeight

Hello everyone. After much background work and some fair amount of prototyping cfcubed and I (with some help from forsakenrider) would like to introduce a very small hybrid amplifier.
 This amp was born out of cfcubed\'s efforts to make a teeny tiny hybrid amp as discussed in this thread,

Teeny Tiny Tube Amp

 cfcubed wrote to me about this idea and, as it turned out, I had been working in the background on a small hybrid that could be powered from a walwart. In this case, however, I wanted the tube to have a higher plate voltage than is available in other hybrids so I had already determined to use a SOHA II voltage multiplier.

 As we discussed what the design goals were we came up with these:

 1. Fit on a 75mm x 120mm board to slot into a hammond enclosure.
 2. Use discrete output buffers.
 3. Elminate the trimpot as used in the SOHA
 4. Generate high than 40V for the tube
 5. Use a buck regulator for the heater supply
 6. Include AMB\'s e12

 It took a while to satisfy all of these requirements, but at this point, after a POC build by cfcubed and some small prototyping by runeight, we think we have a nice little amp. I want to thank cfcubed for all of his great ideas, collaboration and time and prototyping work. 

 cfcubed will be filling in on some of his builds and experience and, in particular, his heater circuit design. And anywhere else that he feels like it. 

 I\'ll be posting each section of the amp with an explanation in follow up posts. We have a board design which is at the fab right now waiting to make a small prototype run. There are enough boards for others to build a proto if you have an interest. Please let us know.

 For now I\'m posting a 3D image of the board and a PDF of the PCB. You can print the PDF at scale to see just how much stuff is crammed onto this board and how tiny it is. 

Compact Hybrid Board

 Here\'s the 3D:


----------



## cfcubed

As from HW, yes this project evolved quite a bit from my original (but not so original
	

	
	
		
		

		
		
	


	




 concept in that "Teeny, tiny, tube hybrid.." thread.

 Initially, I was looking for a transportable tube hybrid that would meet or exceed original SOHA performance with size allowing it to fit in a briefcase. Thought that meant using a pencil tube. Wanted muting delay & to avoid SMD construction. dBel84 and PRR made very constructive comments (esp. PRR pointing me in the direction of switchers). Upon contacting runeight, found he was thinking about the same sort of project.

 With runeight's continual pushing of the envelope (no pots, discrete buffer, etc), what we appear to have now is a mostly no-compromise implementation on a PCB smaller than a 3" by 5" index card. And in a case that fits on your hand http://www.hammondmfg.com/pdf/1455K1202.pdf (albiet, requiring a 24VAC 1A wallwart). Idea is that one could have $20 wallwarts at home & the office and just transport the amp.

 The project offers a good deal of tube rolling possibilities (e.g. 6.3V / 12.6V switchable heater supply - my little design contribution
	

	
	
		
		

		
		
	


	




 and the only hot device in the case should be the tube. 

 There is some compromise, of course, to fit in essentially a 3"W x 5"L x 1"H space (component selection comes to mind, e.g. pots, caps, jacks must adhere to clearance restrictions) and it is still a one-tube design. If the current success we're experiencing with the amp hold, its cost & performance should fall between full SOHA & full SOHA II builds (builders/listeners deciding where the performace lies).

 So we are currently looking to building out a few prototype PCBs (the 1st BoM is nearly complete)... With 400+ holes to fill on a tiny board, prior build experience would help & of particular interest to me would be qualified SQ judgements.

 Attached is a pic of the last POC for the project (has 250v comps in HV instead spec'd 100v)... There are a few minor devations from the current state but with exception of the "pot-less" tube stage, all the individual circuits are in this POC & sound good to me
	

	
	
		
		

		
		
	


	




 All I can say now is whew
	

	
	
		
		

		
		
	


	




 Thumbnail of POC:




 Feb 23, 2009 update: CTH proto PCB stage nearing completion... My CTH is done & I'm liking it:






Tube rolling possibilities here.

Features, etc worded in another way.
*
 March 16th, 2009 update: CTH Design, etc. link available on Cavalli Audio, PCBs, kits available... 
 In addition to all the info + reviews in this thread, there is now a CTH kit thread too.*


----------



## ludoo

I would be very interested in building one of the prototypes. I've built 2 Starving Students, 2 YAHAs, and will probably build a slightly modified YAHA as soon as my Mouser order arrives. My orthos love hybrid amps.


----------



## runeight

*The Buffer*

 Using an off-the-shelf walwart necessitated some important design constraints. And working within 75mm x 120mm necessitated a few others.

 Some hybrids use DC walwarts. This is the simplest way to supply DC power to the amp but it tends to limit the B+ to something less than what the walwart can supply.

 However, if we use an AC walwart, as is used in other hybrids, then we have the opportunity to use voltage multipliers to create a higher B+. How high depends on the voltage from the walwart and the number of stages in the multiplier.

 In this case I had settled on a 24VAC walwart as the starting point. There is an additonal limitation imposed by using a walwart. Since the walwart only supplies two wires there is no CT. And with no CT we cannot create a split supply for a complementary output stage. We could use an SE output stage as in the SOHA II but the power requirements for this are too high.

 So, the two constraints of small space and AC walwart power require that the O/P stage be:

 1. Complementary
 2. Use TO92 size devices
 3. Use a rail splitter to avoid using a large output capacitor

 Number 3 further means that, since the O/P is direct coupled to the headphones, it has to be a self-zeroing buffer. This is because the buffer will be coupled to the tube stage by a small coupling cap.

 After some thought, this is the buffer that we settled on:






 This is a fairly conventional diamond buffer. The O/P devices are the BC327/337 complementary pair and the input devices are the BC550/BC560 pair. These are all TO92 devices. The operating point is rougly 20mA in the O/P. Since each device sees about 12V this makes for about 240mW power dissipation for these 600mW devices.

 The top input device is loaded with a CRD to establish the current in the input stage. The bottom devices is loaded with an opamp controlled current mirror. The opamp/mirror control the offset. There is enough range in the servo to account for most device variations. In this case the complementary devices should be from the same hfe class to minimize any possible problems. For example, BC550/560 should be "C" class and the BC327/337 should be "25" class.

 Notice that the opamp reference voltage is not "ground" but the virtual ground that will be coming from the splitter (VG).

 cfcubed has proto'd this buffer with the splitter (next installment) and the servo is able to maintain very good, small DC offset.

 Since this is a complementary buffer it can go into class AB mode. And while it can't make as much power as a buffer with power transistors it can make enough to power most headphones.

 Two of these buffers, obviously, are on the board sharing a dual opamp for the servo.

 R18 is an optional output resistor to make it easier to control the gain for the wide variety of headphones that can be used.

 Next stop is the rail splitter.


----------



## amphead

Nice work Runeight and Cfcubed! Should make some great sound, based on your other work.


----------



## tomb

Nice work, Runeight and cfcubed! We can always use another tube hybrid in the community!


----------



## runeight

*The Splitter*

 Because the rail splitter sources and sinks the currents in the O/P stages, the "SQ" of the splitter is almost as important as the SQ of the buffers themselves. And so we decided to make the rail splitter look as much like the buffers as possible. This meant a discrete rail splitter with opamp control.

 Like this:






 This splitter is essentially an opamp driven diamond buffer, very similar to the O/P buffers. Except that here the opamp is allowed to operate at AC so that it will keep the O/P of the splitter at the VG point set by the TLE2426.

 This type of splitter is not new or unique, but it is very compact and it works very well in this amplifier.

 Next, the Input Stage


----------



## adamus

love it so far! good use of well tested designs.


----------



## MrSlim

Hey Runeight, I'd love to give a prototype a try.. Im working on a SOHA + JISBOS, as well as having a 41 Hz Amp6 and a Hagerman Bugle in the process..


----------



## digger945

Hybrids rule!
 What kinda tube?(the link for the tiny amp is not working for me)


----------



## runeight

ludoo and MrSlim I'm waiting on proto boards right now. But we'll keep you guys up to speed as things progress.

 digger945, the original teeny tiny amp that cfcubed was working on used pencil tubes. However, we were able to make this amp so small with 9 pin miniature tubes that we didn't really need to use the pencil tubes to space. And doing this means socketed tubes and tube rolling.

 Since cfcubed's heater circuit is switchable between 6.3V and 12.6V any of the 12au7 class or 6922 class of tubes should work. I'm expecting that other tube types will work as well. But we'll have to experiment.

 The link doesn't work for me either. I think because headwize is down for upgrades at the moment.


----------



## cfcubed

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_digger945, the original teeny tiny amp that cfcubed was working on used pencil tubes. However, we were able to make this amp so small with 9 pin miniature tubes that we didn't really need to use the pencil tubes to space. And doing this means socketed tubes and tube rolling._

 

Yes, it became clear during development that it was not desirable to _limit_ the amp to pencil tubes. If there is demand for it, it is possible in a future rev of the board to re-route a couple traces that pass under/within the 9-pin "circle" so that a .5" hole could be drilled in the center. This would allow tubes like 6N16B (shown in POC) & 6111 and others to be recessed within a grommet within that hole & soldered in *and* likely avoid any protrusion above the top of the target case.

 I may DIY one-off pencil tube -> 9-pin socket adapters to compare such tubes to the 12AU7 variants I have on hand... If a 6N16B or 6111 were by chance my favorite in the amp I'd send a request to runeight
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_The link doesn't work for me either. I think because headwize is down for upgrades at the moment._

 

Uh, umm, that thread is a bit embarrassing for me anyway... Let's just say I've learned quite a bit in the last several months (esp. about switchers
	

	
	
		
		

		
		
	


	




) I will have a bit of info in the next few days about the SM heater implementation that was necessary for heat & size restrictions... It seems an ideal choice in this case especially with the higher freq part & secondary filtering we've implemented.


----------



## runeight

*Input Stage*

 As most of you know by now, one of things I didn't like about my orignal SOHA design was the trimpot. This problem is solved nicely in the SOHA II with an input stage that permits a small amount of feedback which, in the SOHA II, really helps with tube rolling and gives excellent performance.

 However, in this amp we don't have room for the nice front end in the SOHA II that needs two tubes. We can only have one tube.

 So how do we set the plate voltage for the tube without loading it down too much (destroying the high frequency response)?

 Like this:






 The triode is set up, more or less, as a simple grounded cathode amp with a CCS plate load and a capacitor bypassed cathode resistor. 

 The opamp is wired so that it simply adds or removes a small amount of current into the cathode circuit to set the plate voltage according to its reference. In this design we've taken the reference, not from the B+, but fromm the V+ because the V+ is regulated and, presumably, steady. Since it's a constant voltage we can use a simple resistive voltage divider for the reference (18k/2k). Using the regulated V+ for the reference also makes the servo mechanism much more immune to changes in the B+ that may be caused by line voltage variations.

 The 1M/33k divider samples the plate voltage. The resistor ratios are set so that with V+ = 24V the opamp will try to set the tube's plate to 75V. It will do this independently of which tube is used so long as the tube can come to an operating point with the current in the CCS, 75V on the plate, and a cathode bias that is more positive than the grid. This will be quite a few tubes.

 The 1k5 cathode resistor is there to pass as much of the cathode current as possible to keep the opamp out of the signal path (the exact ratio of currents, however, depends a lot on the tube in use). The cathode bypass cap helps further with this when signal is applied. In addition, even though the plate load is a CCS so that the cathode current is nearly constant, the cathode bypass cap lowers the Zo of the stage giving better bandwidth for a given load.
 '
 The 1M resistor attached to the plate is a very high load. It will be in parallel with the Zi of the buffer which is also in the megaohms range. Thus the tube sees the high load resistance that we need for good performance.

 The CRD is used here (and in the buffers) to save space. There is no room for fancier CCSs in this amp.

 Next, a new twist on AMB's E12


----------



## MrSlim

Runeight.. thanks for the info.. This looks like its going to be a cool little unit.. It'll only be a little bit bigger than the CuteBatteryII I have on my desk now.... 
 Looks like Headwize had a server crash and they are in recovery mode(all the data is ok though..)


----------



## runeight

*An E12 with Lights*

 Although it's not absolutely necessary to have offset protection on direct coupled amps, it seems to me this is always a good idea. O/P stages like the one here and in other amps rarely fail but when they do, well . . .

 AMB's E12 is a very tiny, but effective circuit. So we have adapted it to this amp. In fact, it's even smaller here because cfcubed insisted on using a smaller NEC relay whose pads are on 0.1" spacing (see the pdf). 
	

	
	
		
		

		
		
	


	




 And then we added lights. This idea came from a request by Uncle Bob on the SOHA II Builder's thread asking if there was a way to put some kind of indicator light on the E12. 

 Here it is:






 This E12 has slightly different timing and threshold from the original. It will trip at about 120mV and trip a little slower than the orignal.

 The lighting circuit lights green when all is well and lights red when the relay opens for any reason, either during startup or because of an offset.

 If you build this, you'll be able to use a dual LED that you can insert under the tube socket. This LED then can light the two colors through tube telling you what condition the O/P is in.

 We did this because we can't help it . . . 
	

	
	
		
		

		
		
	


	




 The next installment will be cfcubed's description of the heater circuit. After that it's time to proto on the new boards.


----------



## fishski13

any ideas on the BOM $$$.


----------



## cfcubed

Quote:


  Originally Posted by *fishski13* /img/forum/go_quote.gif 
_any ideas on the BOM $$$._

 

I believe we have a pretty solid BOM now & I've placed an order based on it that will allow me to build a complete amp using the prototype PCB (due in a week or two).

 It's looking like the cost of a completed amp w/AC adapter and case should come in at roughly $125 USD (plus various vendor shipping costs & any taxes).

 I guess the other question on peoples minds is its performance sound-wise, and this should start to be answered by the proto PCB builders in the coming weeks. But my impression from listening to the POC is that builders are going to be pleased. And the amp is quite capable of driving my low-Z D2000s as well as my hi-Z DT-880s, contrary to my experiences with say, a typical opamp buffered SOHA.


----------



## m0b1liz3

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_ And the amp is quite capable of driving my low-Z D2000s as well as my hi-Z DT-880s, contrary to my experiences with say, a typical opamp buffered SOHA._

 

Wow, this is exactly the type of project I was hoping for my D2000s. I wanted something compact that doesn't take up much space on the desktop, sounds great and can work on 110/240v with a wallwart. I built a Millet Starving Student to that end but this sounds like it would be a step up from that. 

 Any idea on how hard this build will be? Sounds like you will be cramming alot of things into a small board. However I might be interested in prototyping this...


----------



## runeight

There is nothing unusual in the build, but there are a lot of components on this tiny board. If we follow the usual procedure (resistors and diodes first, small caps and transistors and opamp sockets, chokes and bigger caps, etc.) the build will be straightforward.

 The main challenge will be that there are so many devices packed so close together there will be lots of opportunity to put something in the wrong place. So a slow and careful build process will be the best way.

 And, of course, I'm saying this without ever having built one so I really don't know for sure.


----------



## cfcubed

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_Wow, this is exactly the type of project I was hoping for my D2000s. I wanted something compact that doesn't take up much space on the desktop, sounds great and can work on 110/240v with a wallwart._

 

Sounds like a great fit... Tube rolling should be fun & easy too as there are no pots to adjust and with off-board heater switch won't need to open the case. Cost of the amp should be nice too, the small size means reduced case & PCB costs and features like e12 & discrete buffers are onboard.

  Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_Any idea on how hard this build will be? Sounds like you will be cramming alot of things into a small board. However I might be interested in prototyping this..._

 

"Sounds like you will be cramming a lot of things into a small board" - I think this sums it up pretty well
	

	
	
		
		

		
		
	


	




 I believe runeight did a remarkable job WRT PCB layout, as expected, but there are a lot of components there and as I said, about 400 holes to fill. We did try to "reuse" parts where possible to reduce the total # of unique components to mitigate this. One will want to stick to the BoM (e.g. using 1/8 watt resistors, etc.) and we have only 1.1" from surface of PCB to bottom of target case top (watch electrolytics).

 Casework involves off-board wiring of pot, jacks, heater switch and optional power switch. As heatsink room is tight on the 24V reg, might want to case-mount that too. 

 Runeight is handling the distribution of these initial prototype PCBs, so I suppose "he's making a list, checking it twice...."

 Next up for me is heater supply...

 N.B. runeight's post just happened too.


----------



## nsx_23

Would this be too difficult for somebody looking to step up from a CMOY to construct? No SMD parts makes this project very attractive to me.


----------



## adamus

looks doable to me. There are plenty of 3 legged beasts to get mixed up. Other than that its through hole paint by numbers...

 giev it a go, plenty of people on here that would help you. But i would say go for a design that is well tested, this will be in protoype.


----------



## nsx_23

The PIA for me is sourcing parts, especially tubes.......

 I wouldn't mind trying out a prototype though. Doesn't look too difficult, and I'll be sure to get the parts the right way round before I solder


----------



## cfcubed

*The Heater Supply*

 Using a 24VAC wallwart to attain a higher 85V B+ (as runeight discussed) coupled with support of *6.3V and 12.6V* heated tubes presented an early hurdle for the project. With no center-tap, this meant deriving these low voltages from an approximately *35VDC* supply. A transportable amp implies being carried about, and this posed both size and heat constraints. Conventional linear regulation, such as a power resistor followed by a linear regulator, could not be employed.

 Our solution is below…. A switch-mode heater supply, which as far as I can tell, could be a first for DIY headamp projects (although not without precedent for DIY audio). Reasons for this may be: 1) common, low-cost switcher implementations (without ripple filters) are less desirable for audiophile applications; and 2) early, lower-frequency devices require larger passive components and could present issues too close to audible range.






*Edit: We found that C3H needed to be a larger value* to eliminate very faint hum when using 6.3V/high draw tubes w/efficient cans.

 My desire to avoid SMD solutions, especially for prototyping, drove us to National’s (150kHz) *LM2595* step-down (buck) switching regulator. Listening to this implementation in the POC with ripple filter (L1H / C1H), I was unable to detect any audible differences between SM heater and use of a battery for heater supply. The significant ripple reduction we see through use of a post-ripple filter is similar to that seen in figure 17 on page 20 of the LM2595 spec sheet

 National’s Simple Switcher tools were used to drive associated component values and selection. The design uses 0.8A parts and supports up to 600ma 6.3V or 12.6V heaters. In feedback, R1H (9k) alone yields 12.6V and switching R3H (7k) in parallel with R1H yields 6.3V. The LM2595 seems a good fit and *requires no heatsink* in our implementation. Builders will want to follow the BoM components here, e.g. use of low impedance caps, and proper choke and diode values and ratings.
 Higher frequency (260kHz+) SMD switchers could be considered in a future revision to save even more space.

 This heater circuit coupled with runeight’s use of capacitance multiplier filters in HV and LV sections makes for a small, high-quality power supply.


----------



## Bismar

Just out of curiosity, seeing as your going for compact here. Why not take a leaf out of AMB's book and have two pcb's stacked on top of each other? 

 Certainty looks possible with the height of some of the caps in the rendered picture.


----------



## runeight

Bismar, we actually talked about this. It's a good idea. But since we were able to fit everything onto the 120mm x 75mm board after a bit of work, we didn't try to squeeze any farther.

 However, who knows what may happen in the future . . .


----------



## Bismar

Cool, a cube 75 x 75 x 75 would be utterly cool though


----------



## cfcubed

Quote:


  Originally Posted by *Bismar* /img/forum/go_quote.gif 
_Why not take a leaf out of AMB's book and have two pcb's stacked on top of each other? 
 Certainty looks possible with the height of some of the caps in the rendered picture._

 

We sort of let Hammond Manufacturing drive the PCB size 
	

	
	
		
		

		
		
	


	




 Their cases are reasonably priced and available, but not that diverse in the small sizes. Also, there was/is new ground here we'd like to proof and using a single PCB is easier and less expensive.

 WRT to cap heights, we only expect .1" clearance from the tops of C5P & C10P to the bottom of the target case top. There are also off-board components that need clearance (pot, jacks, fuse) that may present a challenge in front panel placement WRT symmetry as it is.

 But, if there is sufficient interest & satisfaction with the amp we can look to further optimize the board (e.g. board mounting some things, more room for coupling caps, etc.)


----------



## nsx_23

With the casing, do you expect it to be difficult, or are you planning on doing some custom front panels kinda like AMB does with the mini3? Heck, a full custom case would be very nice. 

 I'd love to see a group buy for this. I'm really, really interested.


----------



## cfcubed

Great to see/hear the interest! We're hoping it'll nicely fill a niche in current offerings...

 WRT front panel/case offerings, guess this can be considered after the initial amps are built/listened to/etc. Plan to have first full build on proto PCB in 2-3 weeks. More will be known then about the looks of the front panel.

 Interest, experiences, opinions and suggestions from the community can then drive things... Things like board-mounted mini-jacks & pots facilitate standard front panels & simplify the build but can also limit options (esp in such tight quarters).


----------



## nsx_23

I think standardizing the panels and things would make group buys and casing work a lot easier. I know I suck at case work since I couldn't even case my CMOY properly the first time round.


----------



## m0b1liz3

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_I think standardizing the panels and things would make group buys and casing work a lot easier. I know I suck at case work since I couldn't even case my CMOY properly the first time round._

 

Have to say that I agree with that. I think my cases looked pretty cool in the end but they required a ridiculous amount of work and I had to enlist the help of a few friends and coworkers to get access to the tools I needed. (I am in Aus and most of my tools are in Canada). Next time I will just pay for a hammond case that works for the dimensions. I can say "look at what I made" now but no one appreciates the time and work a customized case takes (except for the rest of us at Head-fi!). In the end I just want to get my builds up and running as fast as possible while still looking nice.

 How close is this to being prototyped??


----------



## runeight

Proto boards will probably arrive early next week. Then I will send one to cfcubed and forsakenrider to build out the proto. Perhaps they will take a week to make their builds (have to ask them on the time). If we don't encounter any problems the rest of the proto boards will be available for other prototype builds.

 We can talk about the casing then too. I proposed FPE panels for the SOHA II but not enough people wanted them to make it sensible to order some.


----------



## cfcubed

There's been great feedback & ideas already in the thread... Thanks!

 Because, as runeight said so concisely a few posts ago:

 "_The main challenge will be that there are so many devices packed so close together there will be lots of opportunity to put something in the wrong place. So a slow and careful build process will be the best way._"

 I'm allowing up to one week (of my spare time) from proto PCB receipt to completed build, but I should have PCB populated & tested earlier. I'll try to post the status then (prior to casework) in case others are eager.

 WRT panels, will take pictures and make notes during build *and* consider making PDF panel template/drill guides to help here. Often I find myself in the same boat, try as I might holes just don't align exactly as I intend. 

 Many things can be considered to (possibly) PCB-mount more things, simplifying construction/panel standardization, in a later version of the amp like:
Could/should we reduce size/rating of C5P/C10P?
Can we consolidate one more pair of single opamps?
Could/should we consider faster(260kHz+), more available SMD switcher for heater?
But the more change one makes between PCB designs, the more the new PCB designs start to resemble a new proto runs 
	

	
	
		
		

		
			





 Again, how the community receives the amp will have a lot of influence on things.

 One thing those interested in building out proto boards can do, besides posting to thread/contacting runeight, is figure out how they'll source the more elusive parts in the build; LM2595T-ADJ, 14mm X 7.5mm .8A vert toroid 220uH, 1N53XX CRDs, NEC EC2-12NJ relay (or very similar) and small pot like panny EVJ-C20 or ALPS RK097. If necessary, perhaps runeight or I could assist with that...


----------



## nsx_23

If you could get a whole kit together, that would be even more brilliant.

 As far as casing goes, I'm sure that will be worked out once the prototypes are done and more people start showing interest. The millet custom cases were fantastic looking, so something like that would be great.


----------



## MrSlim

It looks like Jameco has the LM2595T-ADJ, at a decent price:
Jameco Electronics ICs & Semiconductors: NATIONAL SEMICONDUCTOR: LM2595T-ADJ
 No minimum qty, but there would be a minimum order cost I'm sure, unless we buy some other items from them as well. 

 Arrow also carries it, at triple the price, still not a big ticket, again a minimum order is probably required from them. 
LM2595T-ADJ 0135 from National Semiconductor | Arrow Electronics North American Components
 We should probably arrange a group buy on the scarce items.


----------



## MrSlim

Mouser has the NEC EC2-12NJ relay: http://ca.mouser.com/search/ProductD...auz9TRyhaK7A==
 so thats not a biggy..


----------



## cfcubed

Thanks MrSlim... 

 In the current BoM, all the parts / part #s come from Mouser or Digikey (an order from each of them). Mouser having 1N5304s & 1N5313s and Digikey LM2595T-ADJs, decent panny EVJ-C20F02A24 pot and nice chokes (M8403-ND, 732-1428-ND).

 Guess we'll call the BoM ready about the time we call the PCB ready


----------



## m0b1liz3

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_We can talk about the casing then too. I proposed FPE panels for the SOHA II but not enough people wanted them to make it sensible to order some._

 

I suspect it was because they were a little expensive. I wonder if such a thing could be sourced from asia? Pre drilled faceplates would make things go much faster for most people though.

 I think an important point will be to keep the build cost as low as possible while yielding the best possible result. If the case is sufficiently small then I would probably make my own clear lexan faceplate and not worry about the lettering but others may want something more. If a total package was available inexpensively I would go for it. I think small and slick looking is a good goal. 

 I would love it if this build had the same sort of treble as the original SOHA with tighter bass and less background hiss. If the experts building the first run could give us all a detailed comparison it would be much appreciated.


----------



## Nemo de Monet

As far as cases and panels go, I see very little attraction, personally, in building something that looks exactly like that made by everyone else; maybe it's just me, but it seems far too Heathkit-ish, with all that implies. I know a lot of recent projects have been designed around specific enclosures, but - with one or two exceptions, like the Mini^3, they can still be cased up how anyone wants. I know that with portable designs, size - and enclosure choices - are a major design criteria, but when you start getting into larger, more complicated designs meant for home use, it just seems... artificially and unnecessarily sterile, and limiting, I guess. I know it's still DIY even when all the choices have already been made _for_ you, but half the fun, IMO, is picking and sourcing parts in such a way that your creation is at least a little bit unique. (I just see row upon row of amps and DACs that all look completely identical, shouting the line from _Life of Brian_ in unison: "Yes, we're all individuals!"...) Casework isn't _that_ hard, and people without access to drill presses and so on _can_ still do pretty much everything with hand tools. If nothing else, there's really nothing wrong with plastic cases - EMI/RFI shielding is ridiculously overhyped, IMO, and if people are OCD about it, Pac-Tec _do_ make shielded plastic enclosures... which take nice rectangular endpanels, so fabbing personal, one-of-a-kind "custom" endplates at a place like Ponoko or Pololu is accessible to just about anyone.

 I have a sneaking suspicion that the trend towards squeezing the last bit of miniaturization out of designs by mounting _everything_ possible on the board is driving the (hopefully brief) popularity of custom cases and front panels. When the layout is arbitrarily "fixed", and your hole-drilling needs to be accurate to +/-0.5mm, letting someone else do it for you starts to look attractive. It might make sense for portable designs, where space is a primary design criteria, but for "desktop" amps, is there _really_ a good reason not to let people panel-mount stuff where they'd like? Too, from an engineering standpoint, the issue of "future-proofing" comes up: I know everybody likes the little Alps pot (or the big blue one), but if either of those ever become unavailable, their basically unique pinouts spell all kinds of trouble for hobbyists, only because so many PCBs are designed around them.


----------



## tomb

Quote:


  Originally Posted by *Nemo de Monet* /img/forum/go_quote.gif 
_<snip>Casework isn't that hard, and people without access to drill presses and so on can still do pretty much everything with hand tools.</snip>_

 

With respect, casework is an entirely different skill set than populating a PCB with parts and a small soldering iron on a desktop. I'd venture to guess that the great majority of people on Head-Fi and the other forums are either students or young people in dorms or apartments who have neither the access to a drill press or the wherewithall to purchase one and set it up in a proper space.

 Casework _is_ that hard when tubes are involved - if for no other reason than cutting the hole for the tube(s) in the case. Drill bits aren't made big enough that are readily available. Hole saws are almost impossible to handle without a good drill press and a decent punch requires an almost $50 investment - not to mention the socket wrench or breaking bar that's needed to go with it. For that matter, the investment in a good step drill bit comes close to the punch price in some instances (but they aren't big enough, either).

 Tubes also develop a lot of heat - especially if regulated heater supplies are used. Plus, Class A bias on the buffer in tube hybrids develop a lot of heat, too. Either one may require the use of cooling holes, which become very problemmatic without a drill press and extremely tedious even with one.

 Of course, it's runeight's and cfcubed's decision whether to go for custom endplates, case, etc. or not ... Gosh knows, I can certainly list plenty of reasons _not_ to do it (it's a monumental task, for one
	

	
	
		
		

		
		
	


	




), but again with respect - those reasons have little to do with whether they are appropriate for DIY or whether they limit someone's flexibility in building the project.
	

	
	
		
		

		
		
	


	







 P.S. Sorry for my intrusion into the thread. My best wishes for the project - it looks cool!


----------



## cfcubed

You all, of course, make great points... And as expected in different directions
	

	
	
		
		

		
		
	


	




 Some want full kits, some do not want the design limited by those that want full kits. Of course, if a design has PCB landings for jacks, pots, etc. this does not mean builders have to use them.

 Certainly, full kits (& maybe PCB support for full kits) do not happen for designs still in the PCB prototype phase, but can be considered later. 
 How the community receives the amp _performance wise_ will have influence on things at this stage. If an amp's reception appeared as on the order of, say, amb's popular Mini³, this opens up possibilities.

 Re: tomb's comments - Thank you for your input & the kudos you posted earlier... Note though that some of what you say may not apply to _this_ headamp, and there are less impactful ($$) ways of achieving good results :
Heat - As posted elsewhere, the only hot part here should be the tube. A few others get warm, notably the 24V reg on its heatsink and buffer/rail output TO92s. On the order of say, my heatsink-less, lower-bias JISBOS build for example. 
 Our SM regulator implementation for heater, typ operating @ 80%+ eff, only gets hand-warm & that's w/o a heatsink.
Drill, tube holes - My Greenlee stepper bit was like $25 shipped from ebay & works well for all such holes. This with my $60 Harbor Freight drill press works wonders
	

	
	
		
		

		
		
	


	


Heat, cooling holes - Again, we expect little heat to be generated within the case. But, one will need to provide a minium of ventillation through holes or slots. I envision no holes on top of case other than for the tube itself, mabye several on the plastic back bezel (& possibly some along the side).
Cases, general - By using an off-the-shelf case one can provide drill templates as a 1/2 step to custom panels. And, one can always get some customization through color changes. I'm using hammond's "clear" case and gray vinyl dye on the bezels, for example, to try to get something nice
	

	
	
		
		

		
		
	


	



 How about we see how the proto PCB builds go now
	

	
	
		
		

		
		
	


	




 Clearly, this project has a lot of potential when looking at its design, features, operating points, tube flexibility, size and cost. 
 We know sound performance is subjective, and not always related to specifications/features.... 
 Heck until recently I was happy listening to tubes running wwwaaayyy below (plate in the 40s) their recommended operating points (e.g. even below spec sheet curves). And w/lower-power opamp buffers to boot.
 Beauty *is* in the eye of the beholder.


----------



## runeight

Quote:


  Originally Posted by *Nemo de Monet* /img/forum/go_quote.gif 
_As far as cases and panels go, I see very little attraction, personally, in building something that looks exactly like that made by everyone else; maybe it's just me, but it seems far too Heathkit-ish, with all that implies. I know a lot of recent projects have been designed around specific enclosures, but - with one or two exceptions, like the Mini^3, they can still be cased up how anyone wants. I know that with portable designs, size - and enclosure choices - are a major design criteria, but when you start getting into larger, more complicated designs meant for home use, it just seems... artificially and unnecessarily sterile, and limiting, I guess. I know it's still DIY even when all the choices have already been made for you, but half the fun, IMO, is picking and sourcing parts in such a way that your creation is at least a little bit unique. (I just see row upon row of amps and DACs that all look completely identical, shouting the line from _Life of Brian_ in unison: "Yes, we're all individuals!"...) Casework isn't that hard, and people without access to drill presses and so on can still do pretty much everything with hand tools. If nothing else, there's really nothing wrong with plastic cases - EMI/RFI shielding is ridiculously overhyped, IMO, and if people are OCD about it, Pac-Tec do make shielded plastic enclosures... which take nice rectangular endpanels, so fabbing personal, one-of-a-kind "custom" endplates at a place like Ponoko or Pololu is accessible to just about anyone.

 I have a sneaking suspicion that the trend towards squeezing the last bit of miniaturization out of designs by mounting everything possible on the board is driving the (hopefully brief) popularity of custom cases and front panels. When the layout is arbitrarily "fixed", and your hole-drilling needs to be accurate to +/-0.5mm, letting someone else do it for you starts to look attractive. It might make sense for portable designs, where space is a primary design criteria, but for "desktop" amps, is there really a good reason not to let people panel-mount stuff where they'd like? Too, from an engineering standpoint, the issue of "future-proofing" comes up: I know everybody likes the little Alps pot (or the big blue one), but if either of those ever become unavailable, their basically unique pinouts spell all kinds of trouble for hobbyists, only because so many PCBs are designed around them._

 

I think there is some truth in what you're saying. The smaller the amp the more reasonable it is to have pre-fabed enclosure pieces. Just because the location of the auxilliary components becomes more critical.

 That's why the Bijou is produced as separate boards for amp (single channel) and PS. It needs a bigger enclosure where there will be lots of room for location the pots, jacks, etc. and, therefore, lots of opportunity for creative casing.

 OTOH, the SOHA II is a single board with fixed locations for the front panel components, but not the rear. In this case it is a toss up whether someone wants custom panels/enclosure or not.

 In this compact amp the front and back panel real estate will have to be used as efficiently as possible. And so it may turn out that everyone will be happy to just take pre-fab'd pieces because there just isn't any other creative way to do it (assuming the Hammond enclosure).


----------



## nsx_23

Nemo, you should try your hand at sourcing parts here in Australia. 

 Thats why some of us want kits, since many components are often difficult to find overseas or even unavailable. I remember trying to source just a simple ALps volume pot for Joshadot's PCB CMOY, and in the end it took a very nice head-fier to give me theirs (from the US). 

 Also, some of us here quiet frankly aren't too concerned with doing casework, and would rather just have a pre-fabbed case that everything can be throw into and fit first time round.

 Its all about choice. Some will like to do all their own work and source parts individually, and some (like me) would prefer to be able to buy a kit and get building right away (which, for me personally, is the most satisfying bit).


----------



## Nemo de Monet

Obviously, views on casework differ; I have no difficulty cutting tube holes - in 1/4" aluminum - with a hole saw and a hand-held electric drill, and I still maintain that anyone scared of working with metal might just as well use a plastic enclosure and ignore the paranoid hype about RF/EM shielding.

 Regardless, I think that people should be enthused about a design - should want to _build_ a design - because it sounds good, not because it looks pretty.

 Cfcubed said "Of course, if a design has PCB landings for jacks, pots, etc. this does not mean builders have to use them", and that's true, as far as it goes - but, given that board space always seems to be at a premium, I can't help but wonder what better use the space allocated to these sorts of things could be put to. Some things - caps, resistors, diodes, ICs - basically _have_ to be mounted on the board. IMO, those that _don't_ have to be - jacks, pots, switches, whatever - _shouldn't_ be. If people want to put them in what you consider the "obvious" or "logical" spots, then unless we're dealing with portable devices made to cram into the smallest possible enclosure, there's really no reason they can't panel-mount them in the "right" spot and have them up above the board; a mere 5mm is enough to clear resistors, diodes, et cetera with room to spare... Off-board components = more _usable_ (or less _wasted_) board space = more (or better) features = a win-win situation for everyone.

 nsx: That's my point; if you want to give people the whole enchilada, a la Heathkit, then plan from the outset to make complete kits. If not, make projects with enough flexibility to accommodate even those of you in the most outlying areas of the Empire. 
	

	
	
		
		

		
		
	


	




 (I referred before to "future-proofing" of designs, but I think I'll start promoting the plight of you folks down under and use the term "Australia-proofing" instead. 
	

	
	
		
		

		
		
	


	




 ) If people didn't keep designing PCBs with the Alps pots right onboard, you - as an example - could just use whatever stereo pot you could find (or get a $20 stepped attenuator off a Hong Kong seller on eBay), wire it up, and get on with life. I mean, there _are_ pots, switches, jacks, and so on, available in Australia, and just about everywhere else in the world; that they aren't readily, or easily, usable is only because PCB designs are habitually - and for no good reason - inflexible, due to (mis-)design...


----------



## cfcubed

> .. I can't help but wonder what better use the space allocated to these sorts of things (_jacks, pots, etc_) could be put to.

 > ... In this compact amp the front and back panel real estate will have to be used as efficiently as possible. And so it may turn out that everyone will be happy to just take pre-fab'd pieces because there just isn't any other creative way to do it (assuming the Hammond enclosure).

 Perhaps best if the general merits of pre-fab pieces & board-mounted accessories should appear in a separate thread.

 No need to get ahead of ourselves here... Take another look at the proto PCB PDF of this [trans]portable amp and you'll see there is NO room for jacks, pots, etc anyway
	

	
	
		
		

		
			





 We _have_ put all the space to good use
	

	
	
		
		

		
		
	


	




 We think anyway, still have yet to build & hear this PCB version yet.

 I'll try to keep quiet now until I've some nice, little 4.7" x 3" x 1.7" thing to talk about


----------



## m0b1liz3

cfcubed, you have built the proof of concept though right? To your ears does it sound as good or better than your existing SOHA?


----------



## cfcubed

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_cfcubed, you have built the proof of concept though right? To your ears does it sound as good or better than your existing SOHA?_

 

Yes indeed.. Although the POC lacks the improved "pot-less" frontend, I like its sound very much. Didn't want to "tear" myself away from listening to it to inform the development team of the performance of this new design rev. No surprise, really, as it has the combo of tube at better operating point (85V) and discrete buffer. Plan on "re-discovering" the 12AU7 variants I've laying around
	

	
	
		
		

		
		
	


	




 Nice with my hi-Z DT-880s and also with my low-Z D2000s, it is likely this will end up the favorite of my tiny stable (now w/SOHA+JISBOS). Maybe it will be the one that stops me from building others, but probably not due to curiosity & builders itch
	

	
	
		
		

		
		
	


	




 That said, as a design contributor of this amp, always respected runeight's refrain from hyping his designs. Guess he prefers to let those outside the design team do so. In which case I've gone too far already


----------



## runeight

They have shipped and I will get them on Monday and send to cfcubed and forsakenrider on Tuesday. I'm anxious to see these tiny boards. 
	

	
	
		
		

		
		
	


	




 I'll post a photo.


----------



## m0b1liz3

This may be a stupid question but...

 Is the assumption that with a potless front end you are using your computer or mp3 player to control the volume level?


----------



## runeight

Interesting thought, but no, we were just planning for a small off-board pot.

 Nothing but the power jack is on the board. No pot, input or output jacks, power switch or heater switch. To maximize space available for the components.


----------



## nsx_23

hmm, that will make casing a bit tricky.


----------



## runeight

Maybe, but maybe not. cfcubed is already planning how to mount the auxilliary components. We'll see how he does with the proto.

 One thing to remember is that while the board is very dense in 2D space there is room in the vertical dimension to fit lots of things. 
	

	
	
		
		

		
		
	


	




 Nevertheless, a good prototype will tell.


----------



## cfcubed

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_Is the assumption that with a potless front end you are using your computer or mp3 player to control the volume level?_

 

Oops, my mistake, there *is* a volume control! I should be saying "trimpot-less" frontend or maybe auto-biasing or whatever runeight may want to call the use of an opamp in the frontend/tube stage (see frontend design). IOW, unlike many other designs, you will not have to fiddle with trimpots & testpoints when rolling tubes.

 Don't anticipate casework to be hard, but it's all relative I guess. Will use masking tape templates & center punch. E.g. from the thumbnail below notice:
Front panel (plastic) - Gets easy holes for pot & jacks. Since input jack and pot are tied, there are only 6 connections to PCB (IG,IL,IR,OG,OL,OR). I'm using RK097 I have around, but panny EVJ series is fine too.
Back panel (plastic) - Round holes for A/C in, fuse & optional power switch. Fuse is recommended to save your $20 wallwarts in case of build error/short. Small rectangle for heater slide switch. Air holes will also happen.
Top panel - aluminum (removable in target case) - Hole for tube. I'll use my large $25 Greenlee step drill.
Sides (aluminum) - Probably some discrete air holes will be needed.

 Deck of playing cards is shown for size comparison... There are alot of parts going in there
	

	
	
		
		

		
		
	


	




 But most of the bulk is plastic bags. 




 Will be following runeight's _ "a slow and careful build process will be the best way"_ and no beers during this build 
	

	
	
		
		

		
		
	


	



 Confident it will be very much worth the effort.


----------



## forsakenrider

NO BEERS! what... i dunno if i can handle that.
 I got my DIGI order today, over night shipping for 8 bucks canadian.... wow.


----------



## nsx_23

I can't wait to see the finished prototype!


----------



## runeight

Boards arrived today. Off to cfcubed and forsakenrider tomorrow.

 I must admit that I am getting pretty stoked about this little amp. And that's unusual for me. 
	

	
	
		
		

		
		
	


	




 Boards are very tiny and very tiny to hold an entire tube hybrid amp with discrete output stages and a 95V supply and to run from a walwart.

 Good stuff.


----------



## digger945

I guess if your stoked, this must hold a lot of promise.
 Impressive looking boards, they will be packed for sure.
 I look forward to listening impessions.
 If the protos go smoothly, could this be offered pretty soon? A group buy initially?


----------



## runeight

Yes, I think it does have a lot of promise. But, like everyone else, I'll have to wait for our intrepid prototypers to finish and tell us.

 I ordered some extra boards this time and if the amps work out well I will make these available to whoever is interested.

 After that we can consider group guys along with pre-fab'd casing pieces.


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Boards are very tiny and very tiny to hold an entire tube hybrid amp with discrete output stages and a 95V supply and to run from a walwart._

 

I was wondering how this was progressing a while back, and missed this thread. Congrats on another unique design - _that's a lot of little holes_





 Looking forward to reports on the first builds. Great gents!


----------



## Forte

Looks great, Any idea on the cost of the BOM as it currently stands?


----------



## m0b1liz3

I thought he said around 125 USD previously. Too bad that will end up being 250 Aus at the rate the exchange is going! If anyone wants to come stay a few nights at my place I would accept the parts as the fee! I am right near Surfer's Paradise


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_ < snip > Congrats on another unique design - that's a lot of little holes





 Looking forward to reports on the first builds. Great gents!_

 

Thanks for the congrats... Unique & innovative things, based on proven/tested designs, had to happen to make this amp possible. And yes, there are about 160 (though-hole) parts going on this 3" x 5" (75mm x 120mm) PCB. But one does not get something for nothing... Or, in this case, one does not get _everything_ for nothing
	

	
	
		
		

		
		
	


	




 > cost of the BOM

 m0b1liz3 is correct, complete build est. (incl A/C adapt, case, etc.) is $125 USD plus any shipping & taxes. My cost was only $70 Mouser + $11 Digikey orders plus shipping + taxes + cost of PCB, because I had a 1A 24VAC adapter, tube socket & 12AU7s around. 

 This is one heck of a lot of amp for that $$$, regardless of size. And can be lowered through groups buys/supply support down the road. Some bundling could help those overseas too.


----------



## Forte

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_
 My cost was only $70 Mouser + $11 Digikey orders plus shipping + taxes + cost of PCB, because I had a 1A 24VAC adapter, tube socket & 12AU7s around. 

 This is one heck of a lot of amp for that $$$, regardless of size._

 


 Sounds great.
	

	
	
		
		

		
		
	


	




 I have just realised this uses the same 24VAC adapter as my MAX and I also have sockets, tubes and even an enclosure for a SOHA I never built. Could end up a very cheap project(as amps go) if I can pick up any parts locally and limit it to one international order. 

 Put me down for one of the extra boards if not already spoken for.


----------



## dracoV

Very interesting project, it caught my eye just before the headwize site went down. Now I'm following this thread. 
	

	
	
		
		

		
		
	


	



 BTW, Have I missed a post ? I wonder. How is the B+(voltage multiplier) schematic look like?


----------



## runeight

Hi dracoV. I haven't posted the PS because it is very straightforward and/or its design is explained in the SOHA II section of the Cavalli Audio website.

 The LV supply is conventional, using a bridge, a pre-regulator filter section, and then a stock 24V fixed regulator.

 The B+ supply comes from a 3X multiplier. 24V * 1.414 * 3 = 101. In reality it is lower because of diode drops and various losses. Let's say 95V would be typical from the multiplier.

 The mulitplier feeds a primary filter cap which then splits to two capacitance multipliers. The cap multipliers use 22u caps whose effective value is then multiplied by the hfe of the MPSA42 transistors. The base resistors are very large. This reduces the ripple to almost negligible amounts.

 In addition, because the tube stage uses a CCS at the plates and because the servo is referenced to the 24V rail, the input stage has very high PSRR. Between the excellent ripple rejection and the high PSRR the input stage should be clean of PS noise.

 Does this help? If you guys really want to see the schematic, however, I can gin it up and post it. 

 BTW, for those of you who have been following the schematics, you've seen quite a few opamps. But, none of these opamps are in the primary signal path. The cathode servo opamps are bypassed by the cathode bypass caps and the buffer opamps control the current mirrors. The splitter opamp comes closest to being in the signal path because it does have to hold the VG constant during current swings from the O/P buffers. But in all cases the primary active devices are the triodes or the BJTs.


----------



## cfcubed

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_ < snip> If anyone wants to come stay a few nights at my place I would accept the parts as the fee! I am right near Surfer's Paradise 
	

	
	
		
		

		
		
	


	


_

 

Always wanted more reasons to visit the land down under... Taste aside, still have those meter maids making the rounds in SP?
 Ehh, it's half a world away from me (56 days by car according to google maps 
	

	
	
		
		

		
		
	


	




 )


----------



## dracoV

Thanks runeight, I see, this amp uses a similar PS to SOHA II,
 so its power should be a clean one, 
	

	
	
		
		

		
		
	


	




 since SOHA II has filter stages.
 Now I'm really want to hear it sing. 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Does this help? If you guys really want to see the schematic, however, I can gin it up and post it. _

 


 That would be great; it seem this amp PS is a little bit different.
 It use 24V and GND unlike SOHA II which are +15v, -15v, 
 and also cfcubed switching heater.

 Well, a question (kinda off topic but somewhat related)
 The buffer of this amp looks good, can I use it as an upgrade to SOHA?

 Cheers,


----------



## runeight

OK. I'll get around to it.

 I see that you're new to heafi. Welcome aboard. 
	

	
	
		
		

		
		
	


	




 Where are you located?


----------



## dracoV

Thanks for the welcome 
	

	
	
		
		

		
		
	


	




 I often lurk around head-fi, headwize, and some other DIY sites, but did not register 
	

	
	
		
		

		
		
	


	



 I register here to subscribe to this thread, and so I can ask some questions. 
 This forum teach me so many new things and techniques. 
	

	
	
		
		

		
		
	


	




 Oh, I live in Thailand. BTW.

 Cheers,


----------



## cfcubed

Quote:


  Originally Posted by *dracoV* /img/forum/go_quote.gif 
_ < snip >
 Well, a question (kinda off topic but somewhat related)
 The buffer of this amp looks good, can I use it as an upgrade to SOHA?_

 

Although this rail/buffer would represent an upgrade for SOHA, the JISBOS buffer is the way to go to upgrade SOHAs. It's well-documented & better suited for that purpose.

 > Learning from forum - YES & something I've been doing too
	

	
	
		
		

		
		
	


	




 BTW, I've the PCB in hand & its a *perfect* fit for its target case, no surprise but nice to actually see this... Have most of the resistors in & if all goes well will post back w/more this weekend.


----------



## adamus

tight... just how i like it.


----------



## MrSlim

Hey boys, I've been thinking about this. I know its your new baby and you deserve the credit for bringing it to "term", so you get to name it, but if you need a suggestion, I think "CHamp" would be a fun as well as descriptive name..

 I'd love to get a crack at one of the proto boards after cfcubed has done his due diligence.


----------



## runeight

Good idea. Thanks.

 Let's see if cfcubed's proto deserves the name.


----------



## nsx_23

This looks very promising. Can't wait to see the completed build. 

 I'm sure the price will drop if the parts are purchased in bulk.


----------



## forsakenrider

There is actually a small guitar amp called the Champ made by fender.

 I hope my board is in my mailbox when I get home.


----------



## cfcubed

Made a lot of progress this weekend:





 All went very well w/the build... Note in the pic I placed heatsink paddles on the BC3X7s that should be unnecessary, I just had them around. Also, the coupling caps (C4R, C4L) where temporarily removed.

 But it appears that through my pinching of too many pennies (mixing some BC components I had in my parts bin), I've compromised the ability of my OB to zero offset. IOW, choosing random BC5X0s & BC3X7s you have laying around and mixing in some new ones from a different vendor is NOT a good way to save a few $s 
	

	
	
		
		

		
			




 You never know what a builder might do
	

	
	
		
		

		
		
	


	




... They may even ignore BoM notes like _"BC devices should be in the same class. “C” class for the 550/560 and “25” class for the 327/337"_...

 Doing some work soon that should correct that dumb move & hope to have more info in the next couple days...


----------



## cfcubed

Installing the correct BC5X0 devices has completely solved my offset issues.. I'd mixed in a couple class "A" BC5X0s (hFE = 200) with the spec'd class "C" ones (hFE about 500). That was not ideal. Correcting this tonight has resulting in a good sounding, well behaved headamp.





 Need to box her up & listen a while more for meaningful impressions, but liking very much what I'm hearing so far
	

	
	
		
		

		
		
	


	




 Certainly drives my D2000s & DT-880s with authority and has no noise issues that I can detect...

 Good stuff.


----------



## dBel84

excellent work - looks fantastic ..dB


----------



## Bismar

Cool, how easy would be to debug something like that, i can spot only like 3 test points.


----------



## m0b1liz3

I thought that this build was going to use "pencil" tubes. Isn't that the same sized tube from the SOHA? Hard to put it all in perspective....


----------



## cfcubed

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_I thought that this build was going to use "pencil" tubes. Isn't that the same sized tube from the SOHA? Hard to put it all in perspective...._

 

See my post here WRT pencil tubes Is says it all. Take a 3" x 5" (or 120mm X 75mm) index card and look at it. Now imagine this whole headamp on that card. And look at its features, flexibility, design & likely cost.


 Thanks dB! How'd you like to build one
	

	
	
		
		

		
		
	


	




 > Cool, how easy would be to debug something like that, i can spot only like 3 test points.

 Heh, I think there may only be one labelled TP... The rest are used spots (SG, etc.). Dude, its a small board... And crammed. Runeight may add a few more TPs in 1st production run PCBs, that's up to him.

 There's an easy answer here: Make no mistakes & assure all your parts are functional (and proper values) prior to installing
	

	
	
		
		

		
		
	


	




 But seriously, getting voltage readings for runeight to diagnose my wrong OB parts was not hard.. Just had a zoomed image of PCB w/traces & schematic & a steady hand for test probes.

 BTW, listened some more.. My build has ZERO noise. Only thing is a little (expected) hiss when vol turned wwwaaayyy up (about 3X louder than I could bear - starting near full volume). The hiss is far less than the hiss from the LINEOUT of an IPOD when it is powered on (ipod lineout hiss is several times "louder"). This is expected & again has no affect on music at any sane listening level.

 I'm really liking this thing... Chilled to some Norah Jones last night & with eyes closed she was _in the room_. Need to box it up & spend some time with it, but hard to imagine someone listening to it and not being impressed. And its sooo small for a tube headamp
	

	
	
		
		

		
		
	


	



 I could be slightly biased tho, so again builders/listeners all have their own tastes. BUT you can roll a bunch of popular low & high priced tubes in this amp. My EH has range in it for example... Plenty of bass & treble extension. My Raytheon CK5814A, a fav @ 40V in my SOHA, may not be my fav @ 80V in this, but does lend an interesting texture to the sound. My gut feeling is this amp will sound like its tube... Which is what you want out of an amp.


----------



## nsx_23

Ooh, this looks very awesome. 

 Now, for a complete kit group buy


----------



## runeight

You guys can maybe see why I've been getting pretty excited about this amp. 

 I have 10 boards available from the first order. These are what cfcubed and forsakenrider are building.

 Once forsakenrider verifies a second build without problems (cfcubed problems were, as he noted, due to using wrong class transistors and once the right transistors were used the amp came right up) then I will make these boards available.

 We will provide the builders with the BoM as revised from the build process (a few small changes). Then you guys will have to start building. 
	

	
	
		
		

		
		
	


	




 So, if you want a proto board you'll have to get on forsakenrider's case. But wait until he gets his board in the mail.


----------



## Uncle Bob

Has there been any further developments/thoughts on making a pre-drilled enclosure available?


----------



## runeight

Yes, we are thinking on this. First we have to determine where cfcubed and forsakenrider place the pots, jacks, and switches. Then I can cook up the FPE panels.


----------



## Uncle Bob

cool

 I'll keep an eye on developments 
	

	
	
		
		

		
		
	


	




 UB


----------



## wiatrob

Looking great guys. Two boards = Super compact balanced tube amp anyone?


----------



## Forte

Looks very impressive, never seen such a tight layout...

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_BUT you can roll a bunch of popular low & high priced tubes in this amp._

 

What tube types can be used in this amp?


----------



## digger945

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I'm really liking this thing... Chilled to some Norah Jones last night & with eyes closed she was in the room._

 

Oh yea.


----------



## cfcubed

OK, before boxing the baby up thought I'd shoot a couple more pics. 

 I encourage those interested in the amp to read this whole thread (ha ha, hey at least 1st 2 pages) and if a DIYer & interested (not afraid of a couple parts orders & drilling a few holes) contact runeight... But here's a quick run-down of features:
Compact Tube Hybrid fitting on a 75mm X 120mm board (targeting Hammond 78mm X 120mm X 43mm case: http://www.hammondmfg.com/pdf/1455K1202.pdf)
No trimpots in frontend. Rolling 12au7 class tubes consists of turning off amp, pulling one tube & inserting another. Can be 6922 class tubes too (switch for 6.3V / 12.6V heated tubes). Other tube types may also work. SM heater regulator needs no heatsink & only gets about hand-warm.
Runs tubes at about twice plate voltage of some other hybrids such as the SOHA (75V, may change 2 resistors in BoM for 80V)
Uses discrete output buffers, rail splitter.. Driving most types of cans (very) nicely.
Implements AMB's e12 muting delay & offset protection (& red and green LEDs)
Completed build w/case & 24VAC 0.8A+ A/C adapter should come in about_ Edit: $150_ USD plus any shipping & taxes (before any group buys or such)
See my posts for _my initial_ impressions... We have another build on the way & room for more
	

	
	
		
		

		
			



OK, now for the LEDs. During the minute or so muting delay while waiting for tube & buffer to settle in we have the RED of bicolor LED on:



 Or in the unlikely event that the e12 goes into protection mode (about 100mv offset or more). Uses direct-coupled output stage (the best kind of output capacitor - none
	

	
	
		
		

		
		
	


	




, so this protects your cans in the event of build error or (unlikely) part failure.

 After the minute or so warm up we have the GREEN of bicolor LED on.




 This should satisfy your wallet, some audiophile needs and perhaps those of your SO... Maybe even getting some "Oh, that's sooo cute!"s out of the deal.
 Oh, for you lady builders, maybe some "Oh, I'll take that!"s


----------



## m0b1liz3

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_ Oh, for you lady builders, maybe some "Oh, I'll take that!"s
	

	
	
		
		

		
		
	


	


_

 

Er, who are these lady builders.
 I thought there was only one girl on this entire forum lol...


----------



## runeight

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Looks very impressive, never seen such a tight layout...

 What tube types can be used in this amp?_

 

Forte, the heater supply will accomodate 12.6V and 6.3V tubes running anywhere from 150mA to 600mA. The front end servo will accomodate many types of tubes. Its design center, however, is around the 12au7 type.

 These are the types that I think you can roll:

 12au7 variants
 ecc82
 6680
 6189
 5963
 7316
 5814

 6922
 6dj8
 8614 (12.6V 6922)

 6n1p

 12bh7

 12at7 (may or may not work)

 any other tube that has the same pinout as 12au7 and an operating point that is not terribly different.

 There may be more than I have listed.

 Furthermore, because the front end uses a nice servo mechanism you don't have to adjust any trimpots when you swap tubes. The only adjustment will be the slide switch for the heater supply that will select between 6.3V and 12.6V.


----------



## digger945

Is 600mA the limit for the heater circuit, or could a feller mod that to go up to 900 something?


 Bravo and hats off to cfcubed for all the info and pics, thanks a bunch.


----------



## keyid

im interested in getting a board and the updated BOM as they become available.


----------



## Forte

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_These are the types that I think you can roll:_

 

Thanks for that. Have 5 or 6 of the tubes you listed already.
	

	
	
		
		

		
		
	


	




 Am now very interested in one of these boards to build this amp. 
 Is posting interest here OK or should we PM or E-mail you?


----------



## runeight

Posting here is ok for now. Thanks for the interest from those of you who have said so.

 Forsakenrider has his board and parts. Maybe even working on the amp now while cfcubed is working on casing.

 It shouldn't be much longer. Just don't want to have anyone else spend time and $$ until we are very sure of two builds.

 And, I guess I'm going to have to build one too.


----------



## dBel84

gotta resist ....resist ........ aaaaaaah ..dB


----------



## runeight

I thought I should troll the list and PMs for those who have expressed interest. Just so that the boards are not over-promised. These are the folks who have expressed interest in the proto boards.

 Ludoo
 MrSlim
 M0b1li3e
 Nsx_23
 Forte
 Keyid
 Alfiax

 Please let me know if you are on the list but should not be or vice versa.

 I have 10 boards. There won't be any kits for this distribution, but I'll supply a BoM and I will try to build out this portion of the Cavalli Audio website so you won't have to constantly look through this thread.


----------



## cfcubed

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_gotta resist ....resist ........ aaaaaaah ..dB_

 

Now you know that won't be possible...






 Got all casework done & boxed it up tonight in about 4 hours... It really seemed a bit too easy. I have done a couple SOHAs before as a warm up
	

	
	
		
		

		
		
	


	




 PCB itself took me something like 6-8 hrs build time (slow & careful) not including time to use the right/specified BC560s
	

	
	
		
		

		
		
	


	




 Tools included sharpie, rule, patience, large Greenlee step drill bit, drill index, small file and $60 HF drill press (Nemo says he uses hand drill.. Must be steady hands)

 She's been working & sounding fine for over an hour now. Case gets a bit warm as I've case bottom mounted the only part needing a heatsink - the 24V LV reg. Can see myself drilling a nice ring of holes around that chrome tube ring and maybe some more on the sides...

 Changed from EH ECC82 to Raytheon CK5814A last night, tonight RCA 5814a then back to EH ECC82 which I'm liking. Yes, about 8 secs to change tubes makes that fun
	

	
	
		
		

		
		
	


	




 When it gets warmer outside I'll use that gray vinyl dye on the end plates to make it even more sexy
	

	
	
		
		

		
		
	


	




 Here's a shot just before boxup... Gotta say, runeight did a great job on the PCB layout, esp. for a 1st proto run:




 Here it is with cans & ipod for size perspective...




 Here's the back w/fuse, heater 6V/12V slide switch & A/C in... Went w/o power switch cause its easy to use the rear plug.. 




 Guys - you are going to like this thing.


----------



## wiatrob

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_gotta resist ....resist ........ aaaaaaah ..dB_

 

Too....many....projects!!! But that is soooo sweet looking...


----------



## dBel84

no kidding 
	

	
	
		
		

		
		
	


	




 congrats all , this has truly turned out to be a very cool project ..dB


----------



## m0b1liz3

cfcubed, that looks awesome. For sure I am building one of these. Will have to see if there is any interest in an Aussie group buy once it is officially available.


----------



## Forte

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_
 Here's a shot just before boxup... Gotta say, runeight did a great job on the PCB layout, esp. for a 1st proto run:



_

 


 Fantastic job cramming everything into such a small enclosure. Initial impressions sound VERY promising.

 All we need now is to hear from the second prototyper.................


----------



## nsx_23

That looks fantastic! I hope its not too difficult for somebody stepping up from a CMOY....


----------



## cfcubed

Thanks for the kudos everyone... 

 Runeight & I worked long & hard to make this headamp a winner... Mostly runeight's grey matter & my hands
	

	
	
		
		

		
			





 Been a great dev experience... Runeight patiently explaining how things work, why certain approaches are better, etc. but always fully considering others input. The way it should be.
 For example, when I thought opamp buffer & trimpots were o.k. he patiently steered the project away from them. Again, always trying avoiding compromise while still meeting project goals (single PCB, target case, through-hole construction). OK, enough don't want to embarrass him too much
	

	
	
		
		

		
		
	


	




 So loving the amp this AM @ work... I'll be re-discovering my 12AU7 collection in this baby & maybe checking out some 6.3Vers too. Now some answers:

*Ventilation* - WRT my bottom-mounting the 24V LV reg... The good - it uses case as heatsink, the bad - its uses case as heatsink (unfair to other components in there). So some ventilation holes in the top (or use that nice perforated alum) are headed my way.

 > Is 600mA the limit for the heater circuit - 

 Yes, it leaves us the desired 25% current headroom (LM2595 = 1A continuous part, we've used 0.8A parts in BoM). And National's tools say the LM2595 needs no heatsink at these operating points.

 > I hope its not too difficult for somebody stepping up from a CMOY....

 For 1st / 10 proto PCBs would like a bit more experienced builders I should think... But if you've other experience & are somewhat meticulous no problem.
 Imagine going from a 4x4 - 16 piece jigsaw puzzle (CMOY) to a 13x13 - 169 piece one in a space that is about 2X-3X a CMOY. The pieces are numbered tho
	

	
	
		
		

		
		
	


	




 > I've used "cute" in reference to this amp....

 True, but it is kinda like saying Tokyo is a nice, quaint town. In fact my son said the completed PCB reminded him of a miniature NYC. Lots of great things happening on this board... Perhaps too many to call it "cute".


----------



## forsakenrider

Uh oh, Im hearing lots of reference to that "second prototyper". The plan is to have it done by saturday. here we are so far, All the resistors have been mounted. A large print out of the silkscreen image is an absolute MUST.


----------



## Bismar

This amp definitely seems worthwhile building, hopefully someone who has been around this forum long enough will step up to make a aussie groupbuy when the final release boards are out.

 Meanwhile looking at that pic, it seems that a few resistors are mounted perpendicular to the board while the rest are flat against it. Is there any chance in making the board even smaller by converting all the horizontal resistors to be perpendicular?

 I know such a drastic change would be a pita for you designers, but for those people who plan to make their own custom enclosures, the smaller it gets without compromising the ease of build of through-hole components, would definitely make this amp shine more then it already has.

 Also out of curiosity why is uhh.. D3E crooked


----------



## forsakenrider

lots more progress this morning, only caps remain!!! Sheesh I might even get it finished tonight!..... we'll see.


----------



## runeight

Quote:


  Originally Posted by *Bismar* /img/forum/go_quote.gif 
_This amp definitely seems worthwhile building, hopefully someone who has been around this forum long enough will step up to make a aussie groupbuy when the final release boards are out.

 Meanwhile looking at that pic, it seems that a few resistors are mounted perpendicular to the board while the rest are flat against it. Is there any chance in making the board even smaller by converting all the horizontal resistors to be perpendicular?

 I know such a drastic change would be a pita for you designers, but for those people who plan to make their own custom enclosures, the smaller it gets without compromising the ease of build of through-hole components, would definitely make this amp shine more then it already has.

 Also out of curiosity why is uhh.. D3E crooked _

 

Bismar, this could be done. The main reason not to is that stuffing the board is already complex and the silkscreen part labels can easily be mixed up because everything is so close together.

 Tombstoning all of the resistors would pack everything even closer together and it may be impossible to put proper part labels next to each part legibly.

 As for D3E I refer you to the PDF of the board provided on the very first post of this thread.


----------



## amphead

This project looks good, congrats on the progress!


----------



## Forte

Quote:


 Uh oh, Im hearing lots of reference to that "second prototyper". 
 






 Sorry, No pressure. Great to see your build progressing.


----------



## Forte

Just wondering, would it be possible to bottom mount the taller components to lift the board up in the case to expose more of the tube?

 And how large a heatsink would be needed if you didn't want to use the case to heatsink the 24v reg?


----------



## runeight

Forte, I don't think bottom mounting can work. The two large electrolytics will prevent this because they are as tall as the inside of the case. If they are bottom mounted then the tube socket itself will have to protrude through the top.

 A small wrap-around finned heatsink that can attach to the regulator should work. The board was designed with room for this heatsink to stick its fins towards the inside of the box. It may be necessary, however, to provide ventilation above the heatsink to let the heat out.

 I think that forsakenrider is building the amp in this fashion to test this.


----------



## mypasswordis

I just bought a bunch of 12AU7s for this project. I'm not sure if I should just ask for a board now or wait until a kit comes out... depends on how much time and money I have. I definitely do intend to build one at some point in time, though, so I'll be continuing to view this thread with interest.


----------



## forsakenrider

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_I think that forsakenrider is building the amp in this fashion to test this._

 

ACTUALLY, this is the one part Im undecided about. The board is completely populated now EXCEPT that 24v reg. I will dig through my box and see what kind of heat sinks I can find and get back to that idea. 

 Im HOPING my teflon silver wire will be in my mail box tonight so I can complete this... If its not there I will use something else and swap it out later.


----------



## dracoV

So intriguing ... That's a beauty. 
 Seeing One proto finished and read about it, I'm salivating  must resisted indeed. 
	

	
	
		
		

		
		
	


	



 Lucky me, my job is quite busy right now. If it isn't so, I might already begin to build one myself. 
	

	
	
		
		

		
		
	


	




 cfcubed, that's a very neat AMP. I like the Chrome ring. Where did you get it and how much?
 I like to have a couple of that ring as well. 
	

	
	
		
		

		
		
	


	




 If I were in the US. I would love to join
 the proto group as well. 
	

	
	
		
		

		
		
	


	




 pity me ):


----------



## forsakenrider

I have good news my friends!
 Second proto is pleasing my ears as I type with ZERO hic-ups. 

 First impressions: Definition. Someone asked for me to compare to My soha+jisbos.... There is one big difference. this amp drives my 32ohm cans and my 600ohm akgs with no problems. the soha doesnt like the akgs.


 More to come....


----------



## cfcubed

> forsakenrider :_I have good news my friends!
 Second proto is pleasing my ears as I type with ZERO hic-ups. 

 First impressions: Definition. Someone asked for me to compare to My soha+jisbos.... There is one big difference. this amp drives my 32ohm cans and my 600ohm akgs with no problems. the soha doesnt like the akgs. _

 GREAT! Maybe some pix after a bit...

 > dracoV:_So intriguing ... That's a beauty. 
 cfcubed, that's a very neat AMP. I like the Chrome ring. Where did you get it and how much?
 I like to have a couple of that ring as well. 
	

	
	
		
		

		
		
	


	


_

 Thanks! WRT tube protectors see this post


----------



## digger945

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Thanks! WRT tube protectors see this post_

 

Is a "set" just all the parts to make one tube protector?


----------



## forsakenrider

This is where I'm at. Im lovin' this thing!!


----------



## Moontan13

Wow, very nice.

 Having a tube and other hot stuff in there has me concerned though... Is there enough room on the back panel for a small vent fan?


----------



## wiatrob

I haven't seen any temp readings, but I'd assume they aren't sky high - The tube would get warm to the touch, but I imagine the power supply and buffer doesn't dissipate too much heat. Any measurements from the proto team?

 My SOHAII heats up the volume knob with a perforated top! 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *Moontan13* /img/forum/go_quote.gif 
_Wow, very nice.

 Having a tube and other hot stuff in there has me concerned though... Is there enough room on the back panel for a small vent fan?_


----------



## m0b1liz3

How many more proto-typers are working on these? 

 Was 130 the price with the case for this BOM? How many different places did the parts need to come from? This project looks exactly like what I wanted when I first looked into DIY.


----------



## cfcubed

Quote:


  Originally Posted by *Moontan13* /img/forum/go_quote.gif 
_Having a tube and other hot stuff in there has me concerned though... Is there enough room on the back panel for a small vent fan?_

 

Gotta run but wanted to post quick info to this query... The only "hot" items of any significance in this project are the tube & LV 24V regulator. 
 If you look at pics of my build, the tube pokes out through a (slightly) oversize hole in the top. And there are holes on the case sides AND a bunch on the case back. Since I case-mounted the 24V reg, my whole case was getting warm (not by any means hot), so I'm drilling about a dozen 3/16" holes in the top

 There is absolutely no reason for active cooling in this design. Just a somewhat perforated top & a way for cooler air to get in (side, back holes).

 Our TO92 output buffer devices get "quite warm" but are not pushed near their limits, even though this amp is designed to remain in Class A while driving most headphones at sane listening levels.

 Edit: Waitrob - I have a old-style outside thermometer (thermistor on a wire) that I'll use to measure within case temps after I drill those holes in the top. I'll post back with readings but expect them to be quite reasonable (case innards likely to be "warm").


----------



## forsakenrider

Second Impressions:

 After a few more hours (8 or so..) I have settled on an Amperex Bugle Boy 6DJ8. I will compare it to my SOHA even though I dont really think its fair. With the small size, heater switch and "auto-bias" (If I can call it that???), the SOHA is no match. The SOHA is an amp for opamps, as I feel rolling opamps through it was more fun the rolling tubes, but with the jisbos that changed and so did its ability to drive high Z phones. Jisbos are made to handle low Z phones, the CTH is capable of whatever you throw at it. This amp gives me a new meaning to the word definition. Every note is clear and full. This amp drives bass in my AKG's I have never heard before. Highs shine like crystals and the mids smooth out the in between. I seriously have trouble deciding what to listen to. I hear something new in every song I turn to, from heavy metal to classical it all "fits".
 I can not imagine ever wanting another head amp. This fits on my desk, I can swap tubes in a second, plug in any phones and just "be" with the music.


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_
 Edit: Waitrob - I have a old-style outside thermometer (thermistor on a wire) that I'll use to measure within case temps after I drill those holes in the top. I'll post back with readings but expect them to be quite reasonable (case innards likely to be "warm")._

 

Way more advanced than the oven thermometer I pressed up 'gainst the heat sinks on the SOHAII proto! I'm curious about temps...


----------



## cfcubed

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_Second Impressions:
 <snip>This amp gives me a new meaning to the word definition. Every note is clear and full. This amp drives bass in my AKG's I have never heard before. Highs shine like crystals and the mids smooth out the in between. I seriously have trouble deciding what to listen to. I hear something new in every song I turn to, from heavy metal to classical it all "fits".
 I can not imagine ever wanting another head amp. This fits on my desk, I can swap tubes in a second, plug in any phones and just "be" with the music._

 

Wanted to note that my impressions of the amp are very much like the above, but thought/think it carries more weight coming from someone else
	

	
	
		
		

		
		
	


	




 I find it has frequency & dynamic range like no other tube amp I've heard (headphone or otherwise)... Although I've not auditioned other "high-end" headamps, like some of runeight's other designs, think its fair to say this thing will give DIY headamps costing 2X+ a run for your money.

 If you've a 0.8A+ 24VAC adapter & 9-pin mini tube socket around you should be able to have a complete build (incl $15 USD case) for roughly $115 USD plus any shipping & taxes. 

 We've BoM (req orders from 2 vendors), build tips, zoomable PCB & silkscreen images, case hole drill guide and even closeup photos to help... 
 Enough said I think - It's back to the music for me


----------



## Forte

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_I can swap tubes in a second, plug in any phones and just "be" with the music._

 







 I love that description 
	

	
	
		
		

		
		
	


	




 Have you finished casing it up and how hot does the case get with the heatsink?

 Also have you listened to it with a 12AU7 tube?


 cfcubed - What tubes have you tried so far and is there much difference between them?


----------



## forsakenrider

All I have to do Is drill the hole for the tube and heater switch. Maybe a couple in the side but im trying to avoid as much swiss cheesing as possible. otherwise its all boxed up with no top. 

 I have rolled, JJ 12au7 gold pins, RCA 5814a black plates, Conn branded 12au7a Clear top, Bugle Boy 6dj8 and two other sylvania 12au7 varients (crap, what are they?). One of the sylvanias that I didnt like in my soha is much nicer in this amp. The BB 6dj8 is my favourite right now and ive been told its an amazing tube by many. Ive ordered some more variants already to play with. 

 rolllly rollllly rollllllllly rolllllllllly


----------



## runeight

Gents, I believe it's time to send out the rest of the boards. Looking through the thread again, here are the folks who have indicated some interest in a board. Please PM me with contact information. There are 10 boards available.

 Ludoo
 MrSlim
 M0b1li3e
 Nsx_23
 Forte
 Keyid
 Alfiax

 Thanks.


----------



## MrSlim

Runeight.. pm sent..


----------



## HeadphoneAddict

Can't believe wiatrob hasn't asked for one yet... He can always build it for me...


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Can't believe wiatrob hasn't asked for one yet... He can always build it for me... 
	

	
	
		
		

		
		
	


	


_

 

You haven't seen my workbench - I'm having to build a second right now! Is that a request?


----------



## digger945

Should some of the others not have time or funds.....my bench can be cleared for this.


----------



## keyid

pm sent. 

 I have a question how much space is available for an attenuator? H x W x L would be beneficial. Thanks.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_You haven't seen my workbench - I'm having to build a second right now! Is that a request? 
	

	
	
		
		

		
			



_

 

If you want to take it that way, sure... But I don't think you can get two prototype boards, and I'd want to pay for all the parts.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_If you want to take it that way, sure... But I don't think you can get two prototype boards, and I'd want to pay for all the parts._

 

I'm actually very interested to see how such an amp does with Orthos. As Ludoo has suggested, Hybrids seem to have a nice synergy with orthos. dBel and I can attest that it may be Alex's hybrid designs in particular: I have been very much liking the combination of my SOHAII and damped YH-3s.

 I've put in the request. If I'm accepted, we could be auditioning the next time we get together...


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I'm actually very interested to see how such an amp does with Orthos. As Ludoo has suggested, Hybrids seem to have a nice synergy with orthos. dBel and I can attest that it may be Alex's hybrid designs in particular: I have been very much liking the combination of my SOHAII and damped YH-3s.

 I've put in the request. If I'm accepted, we could be auditioning the next time we get together..._

 

At the meet on the 14th we'll have several hybrids to try - Melos SHA Gold, Head-direct EF1, TTVJ portable Millett hybrid, Millett Starving Student Hybrid, SOHA II, and maybe this one but I don't see how it could be done in time.


----------



## digger945

^Will Yoda be there?


----------



## wiatrob

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_^Will Yoda be there?
	

	
	
		
		

		
		
	


	


_

 

*Y*our *O*ther* D*iminutiv*e **A*mplifier


----------



## Forte

pm sent. 

 Has a name been decided on yet?


----------



## cfcubed

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_At the meet on the 14th we'll have several hybrids to try -< snip > maybe this one but I don't see how it could be done in time._

 

Up to runeight & wiatrob I guess... An experienced builder could likely build this in one (busy, uninterrupted) day, but perhaps best spread across a couple.
 Runeight will provide BoM which currently requires a Mouser & small Digikey order assuming you've a tube socket & 1A+ 24VAC adapter.


 > Has a name been decided on yet? 

 Been using Compact Tube Hybrid (CTH), like MrSlim's CHamp... There is the Fender thing & its runeight's call.


 > much space is available for an attenuator? H x W x L would be beneficial

 We spec the small Alps RK097 in BoM, with Panasonic's 12mm EVJ-Y10F03A24 as a "large" alternate. Here's idea of frontpanel clearance:





 > ..drill the hole ... maybe a couple in the side but im trying to avoid as much swiss cheesing as possible.

 Other than the small TO92 BC3X7 devices (which we want to keep happy), the only other heaters we have are the tube (handled by its hole), LM2595 heater reg (max: 0.8W disp) and 24V LV reg (disp more than heater reg). 
 I like to handle heat from the big producers separately from the rest, leaving a nice comfy home for all the other little parts. E.G in my FirstWatt F1/F2 clone I isolated the FET HS so its heat doesn't affect any other innards:




 Being fixated on cooling myself, I looking at perforating the sides & top OR bringing some heat external through use of a tasteful piggyback HS for the regs... Something like this but maybe not as tall:




 Good luck on the builds guys!


----------



## m0b1liz3

Hmm, I think the Champ is a classic guitar amp that has been around since the 50s so you may want to choose a more progressive name for it. 

 As for prototyping, organizing all of the parts orders seems like a hassle to me right now since I have just committed to studying for some big exams. I just want one package with smps, tube socket and parts to arrive at my doorstep!


----------



## dracoV

Two thumbs (ways)UP already. I'll definitely build this AMP. 
	

	
	
		
		

		
		
	


	




 Yes, it deserved a name.
 If you guys don't really have a name or two in mind, could I humbly suggest.
 It just sprung into my mind; putting its main features together.
 Hybrid, even though it's a proper term, but I like word Fusion better 
 So, it's a Fusion amp, walwart powered.
*Fu*sion *W*alwart headphone *A*mplifier
 The word FUWA in Chinese should mean Lucky doll or Good luck doll, 
 so it could represent sth. tiny.




 Cheers,


----------



## MrSlim

Here's another name idea:
*A*lex's *R*eally *C*ompact *H*ybrid. *"ARCH"*

 Then I was thinking it could extend to:

*ARCH* *I*s *E*xcellent.. or *ARCHIE*

 OK.. Im getting silly.. I'll stop now..


----------



## lordvader

+1 for ARCHIE !!!!!!


----------



## cfcubed

Heh, ARCHIE... Anyway wanted to say we calculated the combined heater & LV 24 reg dissipation at less than 2 watts... 
 And my case was not uncomfortably hot even without the top holes, so I've unnecessarily concerned about it.

 But if you wanted to get a watt or so out of your case you could consider top mounting something like the 2PP / 
 Mouser 774-73452PPBA  (*only possible for LV 24V reg, NOT LM2595 (want leads short on that)*. 
 Even that may be overboard
	

	
	
		
		

		
		
	


	




 Probably tiny TO220 heatsinks within the case are fine as long as there are some holes...


----------



## nsx_23

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_Hmm, I think the Champ is a classic guitar amp that has been around since the 50s so you may want to choose a more progressive name for it. 

 As for prototyping, organizing all of the parts orders seems like a hassle to me right now since I have just committed to studying for some big exams. I just want one package with smps, tube socket and parts to arrive at my doorstep!_

 

I also want a complete kit. Maybe a group buy is in order?


----------



## gore.rubicon

if the price is right, sign me up, im a starving student, and the tubes used in this amp (to me) seem a bit more available compared to the 19j6s


----------



## holland

I couldn't resist. My hat's in the ring too.

 20mA before falling out of class A? What are the clipping points into low-Z?


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I couldn't resist. My hat's in the ring too.
 20mA before falling out of class A? What are the clipping points into low-Z?_

 

Great, glad to have you on board... We must be getting close to 10 prototypers by now...

 > _ 20mA before falling out of class A? What are the clipping points into low-Z? _

 Runeight will have to answer this when he takes a break from other things






 Seems to me we aren't driving the BC3X7s too hard using the current BoM comps (don't need the TO92 heatsinks that may appear on it). Think he's slowly putting together something on his site about this amp...

 Since you guys should be getting parts & PCBs soon, here's my personal build tips:
Alps RK097 series pots have 6mm shafts. I used heatshrink on it to use 1/4" shaft knob Mouser 450-6016 (can use straw)
Proto PCB & BoM may req tilting in C5P & C10P slightly to fit board in case.
about a dozen side & top holes may suffice.. I staggered side holes because it's hard for hacks like me to make straight even spaced holes
	

	
	
		
		

		
		
	


	


BoM heater slide sw was smallest I could find (other than the RadioShack 275-406 submini I used). See pic below - can also see my bottom mounted LV reg (again don't need to do that)
Since tube amps like to be on for a while I didn't use a pwr switch... Used fuse instead to protect my wallwart.
If a part is out or has silly min qty consider finding alternate of same type, value, rating & size.
Be careful if probing around the PCB when powered on - its quite tight in there!


----------



## runeight

Here are a few additions to cfcubed's build tips. 
	

	
	
		
		

		
		
	


	




I'll be building out a section of the CA website soon so you'll have a reference for information
The C5P and C10P in the BoM are smaller diameter than the originals, but they have smaller lead spacing. The should fit without tilting if mounted on the inside pad towards the center of the board
DON'T, DO NOT substitute transistors unless you really know what you're doing. The BoM calls for specific gain classes ("25" and "C"). Don't mix gain classes. If you do, the buffers are likely not to be able to zero properly.

 Boards are starting to go out to the next group of prototypers.


----------



## Alfiax

Well, I'm pretty psyched. I just put my orders for components in, so given a small amount of luck with the postal system everything should be in place to start my prototype some time next week. I have a small range of slightly more 'unusual' dual triodes lying around which might work well in this circuit-- if any seem to work well I'll report in...


----------



## cfcubed

Quote:


  Originally Posted by *gore.rubicon* /img/forum/go_quote.gif 
_if the price is right, sign me up, im a starving student, *and the tubes used in this amp (to me) seem a bit more available compared to the 19j6s*_

 

Maybe you meant to put a smiley at the end of the understatement
	

	
	
		
		

		
		
	


	




?

 An ebay - Vintage Elect/Tubes search for the list of tubes that should work in this amp:
*(12au7, ecc82, 6680, 6189, 5963, 7316, 5814, 6922, 6dj8, 8614, 6n1p, 12bh7)*
 yields about 600 hits (600X # of 19j6 listings) ATM. 

 And although you only need one tube for this amp, you'll want to try others... Although a dozen or so brands/varieties may rise to the top of heap, they all tend to have their own distinct qualities. Lots of people will probably have their own favorites in this amp. I liked my EH 12AU7 that I dismissed in my SOHAs. And reading forsakenrider's review I'll be picking up a BB 6dj8 for sure
	

	
	
		
		

		
		
	


	




*Alfiax * - _Well, I'm pretty psyched._
 Cool... Let us know how it goes.


----------



## holland

did I miss the bom post? If not, I'll start piecing parts off the schematic.


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_did I miss the bom post? If not, I'll start piecing parts off the schematic._

 

If runeight has a PCB for you then drop him a PM or something with your email addr & he'll send the BoM.


----------



## wiatrob

Are we assuming the wallwart will be scrounged? I did some snooping in my giant stash of power bricks - 24V 1+ amps are a bit hard to come by (I found none.)

 I sourced one with my Mouser order for about $10.00 - should we just include this in the Bom?


----------



## runeight

I guess we were assuming that they were so ubiquitous that everyone would have easy access to one.

 Mouser does have one as you discovered and we can include it in the BoM. Probably a good idea.


----------



## keyid

I couldnt find one at mouser almost ordered from Jameco, part number please


----------



## wiatrob

507-XR-2440LED


 Should work. It looks like it's the only one (that's not 'medical grade' - that's optional for the power cord crew!


----------



## runeight

I see that I am wrong. I could swear that I found one when we were doing the prototyping, but I don't see one now.


----------



## wiatrob

CRossed posts - look again, it hides...


----------



## runeight

Wow, that's not the one that I thought I found. It's current rating is a bit high, but it should work. Does it have a 2.5mm plug?


----------



## keyid

There is also 20va 24vac version .8amps
507-XT2420
 a couple dollars cheaper.

 But theres no end plugs. 
http://www.mouser.com/catalog/637/1948.pdf
 there is two tabs for the power wire. Im thinking of permanently attaching the adapter to the amp.


----------



## runeight

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I couldn't resist. My hat's in the ring too.

 20mA before falling out of class A? What are the clipping points into low-Z?_

 

The buffers can get to about 2V of the rails so 20Vpp. For low Z phones they will be limited by the current sourcing capacity of the PS. This is because the rail splitter is just like the buffers and it can do everything that the buffers can do.


----------



## keyid

alittle more searching 

 553-WAU24-1000

 AC/AC Adapters 120 to 24VAC 1.0A Wall Plug-Ins 
 They have 2.1mm ends unregulated but not stocked.. nvmd


----------



## wiatrob

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_But theres no end plugs. 
http://www.mouser.com/catalog/637/1948.pdf
 there is two tabs for the power wire. Im thinking of permanently attaching the adapter to the amp._

 

Argh,

 you're right - the previous (more expensive) ones I looked at had the 2.5mm plugs...

 This is what we need:

http://cgi.ebay.com/BRAND-NEW-24V-1A...3A1%7C294%3A50

 Maybe they are more ubiquitous, there are a billion on Fleabay... so this may not be so big a deal


----------



## holland

^ That one is DC. You need AC.


----------



## cfcubed

OK a few things to think about here:
What does the amp draw? *forsakenrider can measure the draw with higher-draw heated tube*, easy way is to pull the fuse & use DMM able to measure up to 2A across its leads. Want initial peak draw & continuous draw readings. W/12.6V/300ma heated tube mine drew about 0.7A.
Plug diameter - I ordered a couple PCB mounted A/C jacks from Mouser & got lucky one matched my adapter... If a RadioShack/The Source/Etc is around you could go there to find a matching plug & solder it in. It's A/C so polarity doesn't matter.
Fuse rating - Thinking the draw w/max heater could be darn near 1A so picked a 1.5A sloblo. This was because I shorted my adapter, opened it up & found a 2A fuse in this 1A adapter. Probably should test/try to lower the fuse rating to 1.25A & perhaps not sloblo to assure it goes before any in your A/C adapter does. This only when you short something by mistake OR bad build error like wrong orientation on PS diodes.

 I just scanned ebay & picked up a pair for like $30 shipped... Then I found this 0.8A one at home & used it. But if I move up to higher draw heated tube I'll use one of my 1A 24VAC ones (the one that now has an external fuse that I installed
	

	
	
		
		

		
			





 Best to stick with 1A min I think.

 One note searching ebay for 24VAC adapter gets a few & always gets the Surveillance type ones *that have no cord*... You could add your own w/plug that works for your PCB mounted jack.... Or go to RS, etc & get plug that matches & solder/heatshrink onto the adapter you find...


----------



## m0b1liz3

Is it possible to figure out a BOM with a SMPS from the least number of vendors to decrease shipping? (Or alternatively would Glassjar audio be able to put something together?) Or would we need 2 rounds of prototypers first?


----------



## Forte

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_Is it possible to figure out a BOM with a SMPS from the least number of vendors to decrease shipping?_

 

I have had a look at the BoM and it lists two suppliers, Mouser and Digikey.
 You should be able to get away without ordering from Digikey however.
	

	
	
		
		

		
		
	


	




 The L1H choke looks like it is available from Mouser, Part No 542-70F336-RC 70F336AI-RC

 The L2H choke and LM2595 Reg can be ordered locally through RS Components.
 L2H Part No 617-1316 Wurth Elektronik | Passives | EMC, RFI and Surge Protection | Inductor Through Hole | Inductors: Suppression 
 LM2595 Part No 533-3664P National Semiconductor | Semiconductors | Power Supply and Control | Variable Switching Regulators | Adjustable Voltage Switching Regulators
 RS do not have these in Australia but list a 6-8 working day delivery time and if you can pick up locally then there is no delivery charge, if not there delivery charge should be a lot cheaper than Digikeys international shipping. 

 The 24V AC 1amp power supply is available locally from Altronics, Part No M9379. This has a cable but no plug, but they have those as well.

 This should just leave the Tubes and socket(apart form the board of course).
 Most Tube vendors also sell sockets. Parts ConneXion & vacuumtubes.net both have cheap shipping options from memory but there are plenty more Tube suppliers to try and most are happy to quote you on shipping if you ask.

 Hopefully runeight or cfcubed can confirm the linked parts are correct, if not confirm for yourself.


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_507-XR-2440LED
 Should work. It looks like it's the only one (that's not 'medical grade' - that's optional for the power cord crew! 
	

	
	
		
		

		
		
	


	


_

 

Yes, those Amseco adapters are the type w/o a wire (see here for pics). But no biggie just add one & pick a plug that matches the PCB jack(s?) you order (order a couple? Goto RS & peruse their plug collection?)

 $11 USD is a darn good price I think for a 24VAC 1A+ adapter esp if combined w/the rest of your order (maybe we should spec a couple in BoM)... 
 Going > 1A (or > 24VA ) is OK just means overly large adapter size.

 > _Is it possible to figure out a BOM with a SMPS..._

 Think jaycar(?) has a straight lead LM2595 you could just bend leads to fit.... Yes, perhaps when production PCBs are around runeight or someone could pursue bundling options (at least enough to build this w/one Mouser order).

 > *Edit: Thanks Forte for more sources!* _Hopefully runeight or cfcubed can confirm the linked parts are correct,_

 Those parts look fine to me... We are looking for 2uH -> 4uH, 800ma min rated L1H and 220uH toroid 800ma min rated L2H that fits. Later I'll post closeup pics of top 1/2 & bottom 1/2 of completed PCB so you can see there is a fair amount of clearance for them...


----------



## Forte

Still working through the Mouser side of the BoM and want to check a couple of things.

 The D1L & D1R Amp diodes list 610-1N5305 followed by the comment  Quote:


 1.8ma 1N5304 or 2.2ma 1N5306 low cost alts? 
 

Has it been confirmed yet if these will work?

 Also noticed most of the caps are rated at 85 degrees. Would it be worth finding 105 degree rated caps, especially for those near the 24V & LM2595 regs?


----------



## runeight

We originally thought that those diodes would work, but I meant to take that option out of the BoM. Please use the one specified.


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_The D1L & D1R Amp diodes list 610-1N5305 followed by the comment 
 Has it been confirmed yet if these will work?_

 

I've got to go now... They will work (using 1.8ma myself), but it's only $5 extra to use the right ones as runeight just said
	

	
	
		
		

		
		
	


	




 I got burned using non-BoM BCs, so best if you follow BoM / runeight speced parts...

  Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Also noticed most of the caps are rated at 85 degrees. Would it be worth finding 105 degree rated caps, especially for those near the 24V & LM2595 regs?_

 

Anything > 85c might be too big. We are quite tight on space here (both diameter & height in some cases), best to stick to BoM parts if possible... Or same type, value, rating & size...


----------



## runeight

Oh, the caps. I don't think that 105d caps are necessary. And they probably won't fit. But, you can always use them if you can squeeze them in.


----------



## runeight

Boards have shipped to those interested. There are two left if anyone wants one. If not, some of the current proto group have asked for more than one. 
	

	
	
		
		

		
		
	


	




 Let me know soon . . .


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Boards have shipped to those interested. ..._

 


 Thanks Runeight! Looking forward to this one...


----------



## cfcubed

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Boards have shipped to those interested. There are two left if anyone wants one. <snip>_

 

Sure _you_ want to wait till the next batch
	

	
	
		
		

		
		
	


	




 Here's top-half & bottom-half pics I was threatening to post... New BoM changes maybe 6-8 resistors & uses smaller diameter C5P & C10P caps.









 Little purple annotations are clues to which TO92s go where, but runeight's BoM + silkscreen PDF are what you'll want to have handy.


----------



## digger945

What do you use to make those annotations?


----------



## cfcubed

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_What do you use to make those annotations?_

 

Adobe Photoshop... 
 I do have a freeware tool that works halfway decent at work - Can let you know its name on Monday if you fire me a PM.


----------



## digger945

Gotcha. Thanks.
 Do you know the circle diameter of the tube socket?


----------



## Forte

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Boards have shipped to those interested._

 







 Great news, Thank you very much.


----------



## cfcubed

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_Do you know the circle diameter of the tube socket?_

 

Putting together a Trivial Pursuit - Tube Amp Edition





? Hey now, that would be fun @ a meet..

 My tube socket measures 22mm dia. BTW builders will be getting a case hole guidance PDF I think...


----------



## Forte

Thanks for the replys, have a few more questions.


  Quote:


 New BoM changes maybe 6-8 resistors & uses smaller diameter C5P & C10P caps. 
 

Does this relate to changes for the next lot of boards only, or do we need to use 12.5mm caps on the proto boards(There is room for 16mm according to pdf)?


 The heater switch on the BoM is listed by Mouser as Momentary, should it be locking?


 cfcubed, Have just read your post on fuses, great info. Does this part
  Quote:


 This only when you short something by mistake OR bad build error like wrong orientation on PS diodes. 
 

 mean the fuses is only need during the build?

 Since there is no need for any adjustments to be made when Tube rolling could an external/in-line fuse be used while building and then ditched once build completed?
 Would mean one less thing to squeeze in....


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Does this relate to changes for the next lot of boards only, or do we need to use 12.5mm caps on the proto boards(There is room for 16mm according to pdf)?_

 

Your "o" version (or newer) of BoM contains the 12.5mm parts... There IS room for 16mm C5P & C10P, as in my pic, but they had to tilt inward a little
  Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_The heater switch on the BoM is listed by Mouser as Momentary, should it be locking?_

 

Ah, that would bad... My mistake. *It sure must be locking.* Essentially any smal SPST, SPDT, DPDT slide or other switch would work. It only either makes or breaks two wires coming off board. Sorry...
*Reason for submini heater slide mounted horizontally & w/small actuator is so that it is not confused with a power switch!*
  Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_cfcubed, Have just read your post on fuses, great info. Does this part mean the fuses is only need during the build?_

 

I guess that gets you the safety when you need it most... During the build & after its confirmed. Up to you though, if a short occurred somehow those A/C adapters are a bear to pry apart.
 Although, as I recall, the 2 or 3 times I blew fuses were from the A/C adapter plug shorting against something on my bench
	

	
	
		
		

		
		
	


	




*BOM UPDATE: Heater slide should NOT be MOMENTARY, let's go with Mouser 10SM002 or RadioShack 275-406 instead.*


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Y

*BOM UPDATE: Heater slide should NOT be MOMENTARY, let's go with Mouser 10SM002 or RadioShack 275-406 instead.*_

 

Too late for me! But I have some small paddle switches left over from my SOHAII build - how much current moves through the switch (It's mounted off board, correct?)

 BTW - Due to a happy accident, I have my board. Nice work _tight clearances._ No cocktails and soldering with this build!


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Too late for me! But I have some small paddle switches left over from my SOHAII build - how much current moves through the switch (It's mounted off board, correct?)_

 

Sorry, no electronics store around? It is off-board & carries virtually no current (1/8th watt?)... Anything that you can't easily switch from 6.3V -> 12.6V by mistake will do... Something that indicates its position is best (like the slide).
 Actually I have an extra RS submini slide I could 1st class mail to you if you can't find one (just let me know through my real emai that you now havel
	

	
	
		
		

		
		
	


	




 Great you have the board!


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Great you have the board!_

 

Parts will all be here Monday - I will have this done for the meet (fingers crossed).

 I have access to good electronics stores (JB Saunders in Boulder) and my parts box is getting *big*. I was just lamenting that I didn't pay attention.


----------



## Forte

The part number recommended for "R16L, R16R, R17L, R17R, R5S, R6S, R7S, R8S" is Carbon Film not the recommended Metal Film?

 A Vishay Dale is available in 6.81 ohm but is pricey.

 Would a RN55D6R98FRE5 be ok at 6.98 ohm?


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_The part number recommended for "R16L, R16R, R17L, R17R, R5S, R6S, R7S, R8S" is Carbon Film not the recommended Metal Film?
 A Vishay Dale is available in 6.81 ohm but is pricey.
 Would a RN55D6R98FRE5 be ok at 6.98 ohm?_

 

Hey you're doing a great job going over the BoM! We'll have to somehow incorp your source/part discoveries for others...

 Re: 6.8s - Forsakenrider & I are using earlier BoM Mouser 299-6.8-RC in our builds.. Think runeight is tweaking comps a bit but don't know how critical the changes are. For example, earlier 2.2ma 1N5306s were on the BoM as alts to save $5 or so but probably best to stick w/speced 2.0ma 1N5305s for consistency in builds.

 WRT heater chokes - I posted the pic a bit back so you could see the clearances... E.G. we have 14mm X 7mm max space for L2H 220uH toroid, but really any 220uH -> 330uH toroid w/min 800ma that fits is fine.

*Edit: Although its important for 1st ten prototypers to try to stick to BoM parts this does not preclude some variation later. * E.G. Forsakenrider & I have a pent up coupling cap demand so we're going in on a soniccraft order. Within only one cap in primary signal path in this amp (C4L & C4R) & about 14mm x 20mm space above board for each of them, we may be trying Gen II 0.22µF 0.27" x 0.73" caps there.
 Also with your help we are down to only 2 non-Mouser parts & that screams for GroupBuy / Bundling down the road.


----------



## Forte

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Hey you're doing a great job going over the BoM!_

 

Have to! Shipping to Australia is either slow or expensive(Mousers minimum shipping for me is $48 AU
	

	
	
		
		

		
		
	


	




) so you don't want to get it wrong or leave anything out since there is a very limited choice locally.


  Quote:


 With only one cap in primary signal path in this amp (C4L & C4R) 
 

Timely post, I had been wondering about the Amp section caps today, look forward to seeing if the Sonicaps make a big difference.
 Would upgrading the Electrolytics in the Amp section have any impact if they are not in the direct signal path? 
 Mouser list a Muse ES Bi-polar at 10u 35v although not available until April and not available any where else I can find. Still not found anything for C1L/R though.


----------



## runeight

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_The part number recommended for "R16L, R16R, R17L, R17R, R5S, R6S, R7S, R8S" is Carbon Film not the recommended Metal Film?

 A Vishay Dale is available in 6.81 ohm but is pricey.

 Would a RN55D6R98FRE5 be ok at 6.98 ohm?_

 

Yes, these are a good sub for the Xicon resistor in the BoM. Nice work.


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_ < snip >
 Timely post, I had been wondering about the Amp section caps today, look forward to seeing if the Sonicaps make a big difference.
 Would upgrading the Electrolytics in the Amp section have any impact if they are not in the direct signal path? < snip >_

 

Cap upgrades & effects have a life all their own on these boards (as do wire types & even # of strands & insulation
	

	
	
		
		

		
		
	


	




... I found this thread interesting WRT coupling caps but you are unlikely to find me spending > $10 USD a on cap
	

	
	
		
		

		
		
	


	




 A tube maybe but not a cap. Although Forsakenrider & I may post back WRT C4 bit, _personally_ don't see much else going on (or needing to go on) in this area.

 IMHO I'd shy away from cap "upgrades" other than _maybe_ those C4 couplers myself. And I don't expect night & day improvement w/Sonicaps there. The amp sounds so good to the two prototypers so far thinking the most noticeable effect will come from tube choice. Of which there is a heck of a lot.
 As before, my fav SOHA Raytheon CK5814A & GE 5963 are unlikely to be favs in this amp as its running tubes much closer to where they are designed to run (80V / 2ma plate). Coupled with flex heater, tubes like Teles, Mullards, Amperex BBs dismissed in amps running tubes at lower voltages & current enter the fray, while more economical/readily available choices may shine too (like my EH).


----------



## forsakenrider

Finished the box up. somehow I dont know how to use a ruler and my tube hole is off... Oh well, its all good. Now to see how hot she gets so I know if I have to add more holes or not...


----------



## runeight

I agree on the cap upgrades. I don't think you would notice any effect from changing out any of the electrolytics or film rail caps. You might notice a difference with a different coupling cap, but also agree with cfcubed that the tube is likely to have a much larger and far more audible effect.


----------



## digger945

^Which is what make this little amp so appealing, the ease with which you can swop many different tubes. Still I think I'm gonna socket C4L/R and maybe try 2 or 3 other coupling caps. I'll wait 'till I get the pcb and see just how much room there will be to play with.


----------



## scompton

I'm curious about what part you use to make sockets for caps and resistors. I've read about doing it but I've never been able to see what part is used and I've not been able to find something at Mouser that looks right.


----------



## digger945

I have a few, depending on the lead size of the component. I use Mouser part numbers:
 575-055210 - This is probably too small for this application.
 575-054800 - again too small I think for this.
 310-13-120-41-001000 - this is a Mill-Max break-apart SIP package, they can be used if you have space or you can break away the plastic housing to make them have a smaller footprint.
 571-1-1571994-0 - another break-away SIP strip, this one by Tyco.
 575-641503 - Yet another Mill-Max break apart SIP socket strip, this one has shorter pin sockets.


----------



## cfcubed

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_Finished the box up. somehow I dont know how to use a ruler and my tube hole is off... Oh well, its all good. Now to see how hot she gets so I know if I have to add more holes or not..._

 

Looking good. Hey I think I'm maybe 1 for 3 of tube holes coming out just the way I want them... What saves my butt are tube protectors (also available on ebay once in a while). Even if the hole is not centered you should be able to make it look centered using one of those rings. You can see I used it to "center" my hole in this shot of the underside:





 The ones for our tubes comes with three rings & the inter-ring spacers. I just use one ring on each build so I can roll tubes. 

 Now you don't have to tell us if that cool ring pattern on the sides was artistic expression OR began as laziness (not changing out the hole saw). It can be a mystery
	

	
	
		
		

		
		
	


	




. I'll go with artistic expression. And you got nice floor confetti to boot...


----------



## MrSlim

So, cfcubed and Forsakenrider, any tube preferences so far? Or how about bang for the buck finds? 

 Anyone have any opinion on Tungsol or JJ Tesla tubes?

 Also, is there room for a 1/4" jack?


----------



## forsakenrider

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_....Now you don't have to tell us if that cool ring pattern on the sides was artistic expression OR began as laziness (not changing out the hole saw). It can be a mystery
	

	
	
		
		

		
		
	


	




. I'll go with artistic expression. And you got nice floor confetti to boot..._

 


 Well I actually drilled the side holes first, what a PITA! the damn rails on the inside pull the drill once you get through the outside layer! then when I was drilling the tube hole with the hole saw I saw the cool ring and figured it might take away the obviousness of a couple crooked holes. I think it worked pretty good for that! ha. I have a few secret plans for the case coming up this month once I get a few things I need. 


 As for tubes, as Ive said before 6dj8 amperex bugle boy. With this tube all notes are full of punch with ZERO harshness. Its simply beautiful! I swear this amp sounds better every time I listen. really sparkles the female vocals and bass is amazingly rich.


----------



## cfcubed

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_Well I actually drilled the side holes first, what a PITA! the damn rails on the inside pull the drill once you get through the outside layer! <snip>_

 

I guess I got lucky with the staggered pattern I used... My holes happened to line up pretty well w/inside PCB slot voids:





 Obvious but we need side holes because the PCB is the full width/length of case (bottom holes wouldn't cut it). BTW I drilled the hole pattern in my top & vinyl dyed the case ends so I should have new pics of my done amp soon.

 WRT to tubes - Will need to spend more time w/them to have more impressions. I do have 3 or 4 tubes on the way to try out


----------



## keyid

Wondering what you guys are using for part # :
 C1E
 581-BF074D0105J
 Boxed Metal Film Capacitors 63V 1.0uf 5%

 the min quantity for Mouser is 100 and its recommended replacement is out.
 Would this be good replacement from Digikey?
495-1119-ND


----------



## runeight

I believe this one will fit:

 505-MKS21.0/63/5

 And I thought I had changed the BoM to use this part number. My fault.


----------



## MrSlim

Runeight, I just sent you an email about the BOM.. 


 Shesh.. while I was composing the message, you answered the C1E question I asked.. 
	

	
	
		
		

		
		
	


	




 there is a 581-BF074D0105JDD but they are going to stop stocking it after the current stock runs out.. (897pcs now)

 JD


----------



## keyid

phew done with mouser, now I just need to find a place to get the adapter and tube socket and maybe some nice hookup wire.


----------



## MrSlim

keyid, I was going to order a socket from this guy:
Premium Ceramic/Gold Noval 9-PIN PCB Tube Socket - eBay (item 150322320372 end time Feb-19-09 18:14:58 PST)


----------



## keyid

Thanks Slim, im been trying to find a place with all three items. Shipping is pretty good too.


----------



## Forte

Can anyone confirm the Pitch of C5P & C10P?

 BoM lists 5mm pitch but pdf of the board measures 7.5mm.


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Can anyone confirm the Pitch of C5P & C10P?
 BoM lists 5mm pitch but pdf of the board measures 7.5mm._

 

Please take a look at your latest emails & if you don't find the info you need drop runeight or myself a PM....


----------



## TimJo

I have a couple of questions that may have been addressed already, but I can't recall for sure, so I'm sorry if I'm asking again. 
	

	
	
		
		

		
			





 The first is grounding the case - do we want the case to be tied to signal ground, or should it just be floating?

 The second is transistor matching - are there any positions where hfe matching is going to improve performance?

 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

 I've got some tubes lined up for rolling once I get this built. 
	

	
	
		
		

		
		
	


	




 GE 5814
 RCA 6189
 Amprex 8416
 CBS 7730
 CBS 7318


----------



## runeight

Transistor matching is not required as long as you use the "25" class BC327/337 and the "C" class BC550/560.

 The case does not need to be grounded but the board's SG pad should be connected to the case.

 Don't forget that the headphone jack's ground must float and be insulated from the case. It is connected to the OG pad on the board.


----------



## sachu

guys what is the parts cost to build this amp? Do we have a BOM established?


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_guys what is the parts cost to build this amp? Do we have a BOM established?_

 

Something like $130 USD complete w/case & adapter but search this thread for "shipping" for details... Should get some international cost feedback once all 10 prototypers are done. This for an amp w/unique & innovative things going on based on proven/tested designs. With a tube compatibility list as long as your arm, discrete rail + output buffers delivering class A into most headphones, no trimpot tube rolling, a single cap in the primary signal path of each channel, built-in e12 delay & offset protection in an amp that fits on your hand. And is impressing the heck out of the two prototypers that have them built
	

	
	
		
		

		
		
	


	




*Here are my initial tube impressions from my meager tube collection (we'll need a tube thread):*
EH 12AU7 - Crisp, full range response. Bass & treble very present, almost akin to having the old "loudness" button pressed. Quite in your face but fun. _Edit: Longer listening - A bit too hard/in-your-face_
Raytheon 12au7 - Like the EH but less so
Raytheon CK5814a - From here down kinda mellow out w/o such noticeable bass & treble extension but lend "interesting" personality to music... May come back to them.
_Edit: Longer listening - I did come back to this & liking it!_
GE JAN 5963
RCA 5815A
Note the list is almost an inverse of my preference for them in SOHA, again running them much "better" here. I've an Amperex 8416, Mullard 6922 & Sylvania 12BH7a on the way to try. Someday I will grab a BB 6dj8 too.

 Quite satisfied w/this amp & I've not heard fancy-pants tubes in it yet


----------



## MrSlim

Guys, We discussed the 24v Adapter from Mouser before XR-2440LED, and although Runeigth thought it might be a bit high at 1.6 A, isn't worthwhile including it on the BOM, since the price is decent, compared to sourcing elsewhere? 

 Although it's overkill, it would then be able to drive some of the higher powered tubes without a problem. I can see where there will be situations where people start trying the higher current tubes and then run into issues with overheating/failing transformers if they go with a lower rated unit. 

 I would also suggest that fuses be mandatory, if they are not already.


----------



## MrSlim

I'm getting ahead of myself, but it occurred to me that two CTH's would fit very nicely into a 1455T2201, for a very small and interesting balanced amp.


----------



## cfcubed

MrSlim are you one of the current prototypers? Don't recall... 
 WRT adapter although it never hurts to have more VA than you need we do not expect the amp to draw more than 0.8A -> 1.0A even with highest support tube heaters (12.6V/6.3V @ 600ma).
 You make a good point though in how much headroom does a wallwart rated @ 1A have.. Think its customary for them to be rated at their max *continuous* draw, but some makers could cut corners. BTW, My 0.833A one gets barely/normally warm w/my 12.6-300ma heated tubes.

 Think waitrob pinged the balanced idea a bit ago... If you are ever going to try it go for a 2.0A+ wallwart
	

	
	
		
		

		
		
	


	




 Oh, up to runeight if that XR-2440LED (w/qty 0) appears on BoM (not a bad idea, just have the A/C jack size business to consider). *Sachu* - yes a BoM is around for proto PCBs.


----------



## MrSlim

cfcubed, yes I Iam, although I was dragging my heels at getting my Mouser order in, while the BOM settled a bit.. 
	

	
	
		
		

		
		
	


	




 I fired it off this morning. I still haven't received the board from Runeight yet, but I'm putting that down to the cross border issues. 

 If I decide to try the balanced route, I'd have to operate on my precious K601's... a scary thought


----------



## wiatrob

Well, here's a teaser pic. Casing and wiring this afternoon. Finger's crossed!


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Well, here's a teaser pic. Casing and wiring this afternoon. Finger's crossed!_

 

Great! Looks good to me...

_Casing and wiring.._ and LV reg HS I trust
	

	
	
		
		

		
		
	


	




 Geez maybe I should change my username to "Heatsink", "BrokenRecord" or something


----------



## digger945

HScubed?


----------



## wiatrob

Now it has one. Glad I got a spare 24V reg! It's pretty tight squueeze... Had to bend two fins to clear C4P, there's a few millimeters between the bottom of the sink and the TO-92s and it's way clear of the D3 and D1...


----------



## sgupt

Wow you guys are amazing! I can't even think about building one of these, let alone designing it.


----------



## forsakenrider

Wow those new Smaller big caps sure are smaller! but they arent BLUE.... ha.

 Lookin good!

 MRslim my board took about 6 business days to Montreal. (I think)


----------



## wiatrob

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_Wow those new Smaller big caps sure are smaller! but they arent BLUE.... ha._

 

I'm going to sharpie up the Xicon's and tell folks they're Black Gates


----------



## cfcubed

Quote:


  Originally Posted by *digger945* /img/forum/go_quote.gif 
_HScubed?_

 

Very witty
	

	
	
		
		

		
		
	


	




 Just checked it looks like Heatsink & BrokenRecord are available names too


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_just have the A/C jack size business to consider_

 

172-0014

 No need to home brew anything, cheap too. It's probably cheaper than buying the plug itself and some wire.

 I don't know if anyone has these lying around, but if you want to be cheap, Jameco has 24V split-bobbin transformers @ $2.xx, with a wallwart case @ $2.xx, it's not bad (shipping alone is high). I've got about a half-dozen of those around so I don't need to buy a transformer/wallwart case, and @ 24V it's 800mA. Just an FYI.


----------



## forsakenrider

oh wow!

 Telefunken 12au7, flat plates. Its like the Bugle Boy 6dj8 with more punch, I love tube rolling.


----------



## keyid

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_oh wow!

 Telefunken 12au7, flat plates. Its like the Bugle Boy 6dj8 with more punch, I love tube rolling._

 

I have couple Tele smooth plates, used for soha yea they are good. 
 The amprex 8416 are great too, my favorites so far are the Siemens. Cant wait to start rolling teh tubes.


----------



## HeadphoneAddict

wiatrob, I'll have a pair of Amperex Bugle Boy 12AU7 to try out in your compact hybrid and my EF-1 on Saturday.


----------



## wiatrob

No Pressure to get it finished by then 
	

	
	
		
		

		
		
	


	




 I have some bugle boy 6dj8's on the way, maybe they'll make it....

  Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_wiatrob, I'll have a pair of Amperex Bugle Boy 12AU7 to try out in your compact hybrid and my EF-1 on Saturday._


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_No Pressure to get it finished by then 
	

	
	
		
		

		
		
	


	




 I have some bugle boy 6dj8's on the way, maybe they'll make it...._

 

No worries mate! Blutarsky is interested in the matched pair of Bugle Boys for his Dared mono-blocks.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_No worries mate!_

 


 Well, I don't think the 6Dj8s will show, but it sounds prett good with these 12BH7s...
	

	
	
		
		

		
		
	


	




 I had an issue with my 24v reg - it was working a little over voltage. Thanks to Alex and Chris and all the prototypers for the help and support.

 Still to do - reroute/make neat the wiring, fix e12 transistor. I haven't had a chance to listen much - I'll take it to work and see if I can get a few hours in today.

 First impressions - quite good SQ from this tiny performer...


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Well, I don't think the 6Dj8s will show, but it sounds pretty good with these 12BH7s...
	

	
	
		
		

		
		
	


	



 <snip>
 First impressions - quite good SQ from this tiny performer..._

 

Great! What a wacky coincidence... I just got my Sylvania 12BH7a in the mail yesterday & was listening to it last night
	

	
	
		
		

		
		
	


	




 Do like it too, maybe somewhere in the middle of my pack of tubes. But, like I posted elsewhere its like blonds vs brunettes... When/if single you find them both fun


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Great! What a wacky coincidence... Do like it too, maybe somewhere in the middle of my pack of tubes._

 

Can you see my little heater voltage dwitchin the picture? It's one of the SOHAII rockers, modified to be SPST and perched on top of some resistor cutoffs. Listening with an RCA BP 5963 now, quite nice. 

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_But, like I posted elsewhere its like blonds vs brunettes... When/if single you find them both fun
	

	
	
		
		

		
		
	


	


_

 

I married a wig-wearer


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I married a wig-wearer 
	

	
	
		
		

		
		
	


	


_

 

Nice... Perhaps I will recommend the same to my wife, but maybe NOT _this weekend_





 And very remiss that I left out redheads.

 Will your little darling be ready for her date this weekend? Don't think the guys would mine what she's wearing... She could even go topless & they wouldn't mind. ( Meaning your new amp, of course, not your wife
	

	
	
		
		

		
		
	


	




 I'd not even try to bring my wife to a meet)


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I married a wig-wearer 
	

	
	
		
		

		
		
	


	


_

 

Can my wife borrow one of her french maid outfits when you come to the head-fi meet tomorrow? I'm gonna see if I can get my wife to wear it for me some night soon...


----------



## wiatrob

Ready *and *Topless, yes! Listened to her a bit today at work with the gamma-1 - nice combo.

 Don't have a maid's outfit, but the latex nun suit will fall right off her - er, the amp...


----------



## wiatrob

A pic from our meet, this amp belongs on a table with the bigger boys... Very nice sounding with headphones (RS-1s) costing 5X what the amp does


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_A pic from our meet, this amp belongs on a table with the bigger boys... Very nice sounding with headphones (RS-1s) costing 5X what the amp does
	

	
	
		
		

		
		
	


	


_

 

Is that 5x including the $250 6-foot APS V3 cable? 
	

	
	
		
		

		
		
	


	




 The amp sounded very good to my ears, and I should have spent more time with it, but I didn't need a lot of time to listen to know I liked it.


----------



## nsx_23

I need one of these tube amps in my life. Badly.

 Finished the mini3 earlier today, and the smell of solder fumes is addictive.


----------



## gore.rubicon

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_I need one of these tube amps in my life. Badly.

 Finished the mini3 earlier today, and the smell of solder fumes is addictive._

 

are you sure the fumes arnt getting to you


----------



## wiatrob

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_I need one of these tube amps in my life. Badly.

 Finished the mini3 earlier today, and the smell of solder fumes is addictive._

 


 The smell of hot tubes is almost as addictive as the sound, my friend!


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Is that 5x including the $250 6-foot APS V3 cable? 
	

	
	
		
		

		
		
	


	




 The amp sounded very good to my ears, and I should have spent more time with it, but I didn't need a lot of time to listen to know I liked it._

 

Just round it to 8X! 
	

	
	
		
		

		
		
	


	




 Naaman inspired me - I'm working on hardwood ends and details for this build...


----------



## Wilf

I think that this will be my first valve amp build, even found some old ECC82 tubes in my Dads garage, which'll be nice.

 Out of interest, if the prototype builds go well, when do you guys think that the first pcbs will be on sale?


----------



## runeight

I'm working on that now Wilf. I'll try to have an answer once we are satisfied that the proto builds don't have problems (or at least only a few problems).


----------



## nsx_23

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_The smell of hot tubes is almost as addictive as the sound, my friend! 
	

	
	
		
		

		
		
	


	


_

 

Yep, so now I just need to wait for a full kit group buy 
	

	
	
		
		

		
		
	


	




 I hate doing casework....


----------



## Wilf

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_I'm working on that now Wilf. I'll try to have an answer once we are satisfied that the proto builds don't have problems (or at least only a few problems)._

 


 Cheers!

 I'm looking forward to this!


----------



## wiatrob

All-

 Here's an comment on the Compact Hybrid from the meet:

http://www.head-fi.org/forums/f45/co...ml#post5427864


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_All-
 Here's an comment on the Compact Hybrid from the meet:
http://www.head-fi.org/forums/f45/co...ml#post5427864_

 

Thanks Bill... Great that some got to see 'er at the meet. Nice to hear others liking its sound.

 I'm finally _really_ done w/mine. Here's pics w/vinyl-dyed ends (yes there was a bit of dust in the garage) + water slide decals:












 Have some more tubes on the way to roll... Just have to make sure I get that 6V/12V heater switch right


----------



## forsakenrider

That is a darn nice knob the cf. I need to find me a nice lil' knobber. If your done does that mean you got the new caps in there? or did they even come yet (I forget).


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I'm finally really done w/mine. Here's pics w/vinyl-dyed ends (yes there was a bit of dust in the garage) + water slide decals:_

 

 Welcome back - Very nice build! I'm now in the process of 'finishing' my amp up. I cobbled together some end panels from some hardwood scraps I had bought off Fleabay a while back... Blurry on purpose 'til I get it finished...


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Welcome back - Very nice build! I'm now in the process of 'finishing' my amp up. I cobbled together some end panels from some hardwood scraps I had bought off Fleabay a while back... Blurry on purpose 'til I get it finished...
	

	
	
		
		

		
		
	


	







_

 

Nice, a little naamanf did rub off on you. I hope you washed your hands though! 
	

	
	
		
		

		
		
	


	




 j/k


----------



## nsx_23

Argh, all these photos are making me jealous. I've so got to get my hands on a tube amp.


----------



## forsakenrider

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Welcome back - Very nice build! I'm now in the process of 'finishing' my amp up. I cobbled together some end panels from some hardwood scraps I had bought off Fleabay a while back... Blurry on purpose 'til I get it finished...
	

	
	
		
		

		
			








_

 


 It looks like you and I have the same idea for the front panel placement... different from cf's "backwards" front panel 
	

	
	
		
		

		
		
	


	




 Dont worry CF, its ok to be different even if your wires are longer.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Nice, a little naamanf did rub off on you. I hope you washed your hands though! 
	

	
	
		
		

		
		
	


	




 j/k_

 

Thank's Larry. I have a bit of work to do before I can catch up with his craft - it was inspirational!

 I also replaced C4L/R with some pre-loved Wimas - I have some .22 100V VitQs but they'd be a real squeeze, and it sounds great anyway!


----------



## wiatrob

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Argh, all these photos are making me jealous. I've so got to get my hands on a tube amp._

 

Why, Yes, you do! and this is an awesome one to start with...


----------



## nsx_23

Right, so the BOM is confirmed, and I'm assuming PCBs can now be ordered?

 If I can get everything from an Australian electronics store without being charged a ridiculous amount of money, I'll build this. Tubes will be an issue though...


----------



## cfcubed

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_That is a darn nice knob the cf. I need to find me a nice lil' knobber. If your done does that mean you got the new caps in there? or did they even come yet (I forget)._

 

I posted the Mouser # for the knob somewhere... It's a 1/4"er w/heatshrink to do the alps 6mm. *Note: I had to trim the BoM pot shaft - its a bit long*, perhaps we can get by w/the shorter shaft alps pot...

*forsakenrider* - Yes, the Sonicap Gen IIs are tombstoned in (_Edit - perhaps not a good idea - PM for details_). And all your goods will be in the mail to you within the next day or two
	

	
	
		
		

		
		
	


	




. Maybe if I focus closely I can hear improvement w/them in C4s but wouldn't bet on it in an A/B comp... Makes me feel better though
	

	
	
		
		

		
		
	


	




 Regardless, love the sound & love it even more when rolling some tubes I dismissed in SOHA in this.

*wiatrob* - Those end panels are looking great! Tubes do deserve & look best w/a bit of wood IMO. BTW know my front panel is reversed.. Let's call it a lefty version
	

	
	
		
		

		
		
	


	




*nsx_23* - If things go well across the proto group something may happen WRT bundling... As someone who bought a glassjaraudio kit in the past, sure is nice getting everything in one box... Esp. for non-US folks I bet.


----------



## wiatrob

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Right, so the BOM is confirmed, and I'm assuming PCBs can now be ordered?

 If I can get everything from an Australian electronics store without being charged a ridiculous amount of money, I'll build this. Tubes will be an issue though..._

 


 We still have a few proto builds to complete as CFcubed implied- so I don't think there's an ETA on production boards - 


 I get tubes from Ebay, I checked Ebay.au - not a whole lot there now but if you keep your eyes open I'm sure you can score a 12au7, 5963, or such for <$10 (us)...

 If you can't PM me if you build the amp and I'll see what's kicking around the tube box...


----------



## MrSlim

I'm still waiting for the proto board to arrive(and the Mouser order, since I used USPS instead of FedEX). Wiatrob was in the second phase of prototyper's and a few other people have theirs in the works. I guess I'll have to put some extra spit into mine, since they're saving the best for last..  

 I stopped at a local electronics store this morning and they had the Hammond case specified in the BOM and my first reaction was "Holy Crap that thing is small.." Have any of the phase 2 guys tried putting RCA's on the back of the box? I know a few of us ordered the 1455K1602's for a bit more room..


----------



## wiatrob

There might be room for RCAs provided they are not very deep - be aware that they will be in close proximity to the switching PS if they are mounted on the back of the case...


----------



## MrSlim

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_There might be room for RCAs provided they are not very deep - be aware that they will be in close proximity to the switching PS if they are mounted on the back of the case..._

 

Hmm.. I don't like the sound of that at all.. May have to rethink my idea.. 
 or put the rca's on the front ...


----------



## cfcubed

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Hmm.. I don't like the sound of that at all.. May have to rethink my idea.. or put the rca's on the front ..._

 

Since you'll be using shielded wire for all input runs perhaps not as "bad" as it may seem from the SMPS perspective. Note also we're using a 150kHz part - audible resonances would appear very unlikely...
 BUT the back is also where the A/C comes in & that's another story


----------



## dracoV

:O Just to look at those finished AMP, I love it already 
	

	
	
		
		

		
		
	


	




 Since it's near the end of proto phase, may I have a little request?
 I was checking for the parts availability from local shops; only two parts that I couldn't find
 were the two CRD 1N5313 and 1N5305. They seem to be difficult finds as even digikey does
 not carry one.
 Would you possible to provide some alternative circuits as in the SOHA CCS 
 (I couldn't find LND150, so I used J113 instead).
 It's no need to change in PCB design just for someone who's willing to build them on 
 small daughter boards and piggyback 'em on the main PCB.

 That'll be a great help. 

 Cheers,


----------



## nsx_23

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_*nsx_23* - If things go well across the proto group something may happen WRT bundling... As someone who bought a glassjaraudio kit in the past, sure is nice getting everything in one box... Esp. for non-US folks I bet._

 

Yeah, I'll kill for a kit, especially since my casework is shoddy as hell. I'm not so worried about the circuit construction, more the caseworking.


----------



## Forte

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Right, so the BOM is confirmed, and I'm assuming PCBs can now be ordered?

 If I can get everything from an Australian electronics store without being charged a ridiculous amount of money, I'll build this. Tubes will be an issue though..._

 

This may help. Directory of Australian Valve Suppliers Not a complete list by any means and biased towards Radio valves but several mention 12AU7's. 

 Also any local Music Store that sells Guitar amps may have spare 12AU7 & 6DJ8 tubes as well. Local sellers will usually be expensive though(They had to ship them from somewhere)
	

	
	
		
		

		
		
	


	




 E-bay from the USA is still your best bet. I received 5 X 12AU7's Monday that cost me less than $6 AU per tube inc shipping.
 Look for sellers that test their tubes and list the test results/values rather than just saying tested good.


----------



## nsx_23

Who's a good seller though?

 I have never owned/built anything with tubes yet.


----------



## MrSlim

Thats where the Tube Adventure begins my friend.. Buying different tubes, trading with others, trying various different ones. That's where CTH is very cool because it will accommodate many different tube models.


----------



## wiatrob

Take a peek:

http://www.head-fi.org/forums/f6/pos...ml#post5438291


----------



## olblueyez

I hope this ends up in kit form, if it does then I want 3.


----------



## nsx_23

^ I'd be in for a complete kit with custom panels/case


----------



## olblueyez

Yeah, I am thinking they would make great gifts. I also have a nice stash of 12AU7/ECC82 tubes for my Raptor and that makes it even sweeter.


----------



## nsx_23

Hmm, I'll need a kit with tubes.


----------



## Alfiax

Well, I'm impressed. My SOHA Jr. (or whatever it eventually will be called) is up and running, and it's sounding pretty great with an RCA 5963 that I fished at random out of the 'AU7 box. I tend to fall in love with every new amp that I build, but I think this little guy is something special- a true all-around performer. Once I get the casing finished up I look forward to exploring the various dual triodes in my collection to see how well they fit.

 It was a little trouble getting here, as my left channel DC offset wouldn't settle properly at first. Happily, Alex and I managed to work out an adjustment to the servo mechanism that solves this problem and makes the amp warm up faster to boot. The final version of the amp will have this modification by default.


----------



## nsx_23

Would you say it was a difficult build?


----------



## Alfiax

Quote:


 Would you say it was a difficult build? 
 

Not exceedingly difficult: the process of assembly was similar to any other through-hole board. However, the density of parts on this board is significantly higher than in most amplifiers, which leaves out several luxuries present in other builds. For example, part labels are small almost uniformly under parts, making verification of correct placement sometimes difficult, and the connection points for inputs, outputs, and switches are in somewhat odd locations when compared to the nice terminal blocks that you would get with a SOHA II or Millett Hybrid. I made one transposition of parts during initial assembly, which required desoldering and replacing four transistors, and as mentioned above I had some issues with the prototype circuit which should not be present in the final build.

 On the plus side, there are no adjustments to make, and casing, the weak point of myself and many others, does not require the precision needed for amps where headphone jacks and volume potentiometers are integral to the board. Overall, I'd say with few reservations that anyone who has previously completed an amplifier of moderate complexity should have little trouble building this. From your sig, you've been making CMOYs- has that been going well? Have you had problems with any that you managed to successfully debug? If you're confident you can run through assembly and do basic debugging (ie, multimeter measurements, desoldering parts) then I'd say go for it.


----------



## wiatrob

Alfiax... thanks for your diligence in tracking down the servo issue - it's what the proto process is all about. We de-solder so you don't have to!

 As to complexity, everything you said is true. I had just come off a the Gamma 1 build, with a few surface mount chips but lots of room around them. The build requires some dilligence, but if you follow some DIY best practices (keep large printout of the silkscreen, measure and double check everything, mark off parts as you go) it's quite straightforward, but I would say get a few builds under your belt before attempting it...


 BTW, the stupid 'light pipe' I built was bugging me, so I tweaked some of the LEDs: http://www.head-fi.org/forums/f6/pos...ml#post5441867


----------



## wiatrob

Quote:


  Originally Posted by *Alfiax* /img/forum/go_quote.gif 
_...Once I get the casing finished up I look forward to exploring the various dual triodes in my collection to see how well they fit._

 


 This is a great sounding amp - I haven't been listening to anything else -of course my other builds are all getting cased 
	

	
	
		
		

		
			





 But I think it does offer an amazing level of performance for the price...

 I can't recommend the 12BH7 strongly enough for this amp...


----------



## nsx_23

Quote:


  Originally Posted by *Alfiax* /img/forum/go_quote.gif 
_Not exceedingly difficult: the process of assembly was similar to any other through-hole board. However, the density of parts on this board is significantly higher than in most amplifiers, which leaves out several luxuries present in other builds. For example, part labels are small almost uniformly under parts, making verification of correct placement sometimes difficult, and the connection points for inputs, outputs, and switches are in somewhat odd locations when compared to the nice terminal blocks that you would get with a SOHA II or Millett Hybrid. I made one transposition of parts during initial assembly, which required desoldering and replacing four transistors, and as mentioned above I had some issues with the prototype circuit which should not be present in the final build.

 On the plus side, there are no adjustments to make, and casing, the weak point of myself and many others, does not require the precision needed for amps where headphone jacks and volume potentiometers are integral to the board. Overall, I'd say with few reservations that anyone who has previously completed an amplifier of moderate complexity should have little trouble building this. From your sig, you've been making CMOYs- has that been going well? Have you had problems with any that you managed to successfully debug? If you're confident you can run through assembly and do basic debugging (ie, multimeter measurements, desoldering parts) then I'd say go for it._

 

I found the CMOY relatively easy to build, and I also finished building a mini3 and RA1 clone. 

 Sounds like I'll have to be extra careful when placing components since they're so close to each other. With the mini3, I didn't find that hard because I had the parts list and parts marked so I could just follow the PCB (I can't read schematic).


----------



## grendel23

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I can't recommend the 12BH7 strongly enough for this amp..._

 

I am running 12BH7A's in my SOHA II, and agree that they sound great.


----------



## forsakenrider

Oh noes!!! look what you guys did, now im gonna have to head to the bay and find some 12bh7s!!

 Good thing im not married.


----------



## wiatrob

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_Oh noes!!! look what you guys did, now im gonna have to head to the bay and find some 12bh7s!!

 Good thing im not married._

 


 Lucky you!I have a lot of postponed chores to do this weekend!
	

	
	
		
		

		
		
	


	




 In all fairness, my SO was very tolerant while I was 'prepping for the meet' last weekend...

 Would you like a BH7A? I'd be happy to send one up your way...


----------



## forsakenrider

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Lucky you!I have a lot of postponed chores to do this weekend!
	

	
	
		
		

		
			





 In all fairness, my SO was very tolerant while I was 'prepping for the meet' last weekend...

 Would you like a BH7A? I'd be happy to send one up your way..._

 

Well that would be mighty kind of you, Is there any 12au7's you would like? maybe we could make a trade. PM me your rules for engagement, Yarrrr.

 I think this amp is going to promote this sort of tube trading thing to the EXTREME!


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Lucky you!I have a lot of postponed chores to do this weekend!
	

	
	
		
		

		
		
	


	




 In all fairness, my SO was very tolerant while I was 'prepping for the meet' last weekend...

 Would you like a BH7A? I'd be happy to send one up your way..._

 

Why did we not try my Amperex Bugle Boy 12AU7 or my 12BZ7 from Woo on the Cavalli Compact Hybrid?


----------



## cfcubed

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Why did we not try my Amperex Bugle Boy 12AU7 or my 12BZ7 from Woo on the Cavalli Compact Hybrid?_

 

WRT 12BZ7 think that's 100mu & I thought the 25mu tube in the POC was pushing my gain prefs driving D2000s... But I think forsakenrider used a tube w/gain > 25mu (_Edit: the BB 6dj8_) & was happy enough, so who knows.... 
 Although he liked his BB 6dj8 in this think he's enjoying a Tele in it now. Much fun to be had here.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Why did we not try my Amperex Bugle Boy 12AU7 or my 12BZ7 from Woo on the Cavalli Compact Hybrid?_

 


 Time, Larry, Time! 
	

	
	
		
		

		
		
	


	




 I am planning on loaning you this amp for a bit in the near future, if you're interested..


----------



## cfcubed

A little status update: I think about 1/2 the proto builds are at or near completion. And those w/completed/debugged builds like what they hear.
 There have been a couple BoM tweaks that impacted the first of the 2nd wave of builds and that coupled with the occasional build error have been/are being resolved in the proto builds. 
 A 1% error rate on this project translates to a couple misplaced components, but builders (w/runeight's help) have thus far been able to resolve things. The features, flexibility & performance characteristics of this amp do not come for free parts-count wise. But payoffs and benefits in terms of performance, size, tube rolling, etc are being realized.

 I believe the plan is to try to clear the current (careful
	

	
	
		
		

		
		
	


	




 near-term proto builds first and hear the feedback.

 BTW I'm not the only one enjoying tube rolling in this & my latest acquisition is an early 60's Siemens "chrome plate" 12au7... Know the shiny plates are more of a gimmick, but finding the rest of the tube shines as well in this amp. It will be staying in for a while. Found this helpful read WRT tube types.


----------



## keyid

completed the proto board over the weekend. Initially tested it out with a cheap stereo pot feed by alien dac and its quite impressive. Switched source to zapped zhoulu and has taken the amp to another level. The amp makes tube rolling extremely fun.


----------



## forsakenrider

Its my birthday and I have the day off from work! The postman brought me My package from CF! WOOT! genII's are in, so heres a lil teaser for ya! MIAAAAAAAAAMMM!!
 First impressions, they add MORE detail. Quite a bit more. My highs are soo clear between notes its unbelievable. Thats why i love this amp, the pure air is amazing.

 Thanks Chris!


----------



## keyid

Happy bday! 

 To my surprise and idiocy one of my dual input rca's wires were dangling around and touching each other. Once they were separated, the sound got way better. The bass finally exploded and the details let loose. Right now in listening with the telefunkin smooth plates and its giving me the in the studio jazz experience. I also got some sonic caps too .22uf 200v but im going to enjoy the default setup for a bit.


----------



## cfcubed

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_Its my birthday and I have the day off from work! The postman brought me My package from CF! WOOT! genII's are in, so heres a lil teaser for ya! MIAAAAAAAAAMMM!!
 First impressions, they add MORE detail. Quite a bit more. My highs are soo clear between notes its unbelievable. Thats why i love this amp, the pure air is amazing.
 Thanks Chris!_

 

Cool! You are welcome there & Happy Bday... Since the Gen IIs went in w/my Siemens chrome plate, maybe even I am hearing their difference
	

	
	
		
		

		
		
	


	




 Yeah I too am enjoying the range tubes have in this baby... As someone said around here, tubes seem to like running in runeight's designs (light loading, etc.)... They seem free to express themselves very well (better than I can
	

	
	
		
		

		
		
	


	




 )


----------



## keyid

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Cool! You are welcome there & Happy Bday... Since the Gen IIs went in w/my Siemens chrome plate, _

 

How are those Siemens Chrome plates? ECC82? 
 Tried to get them but I keep getting sniped on ebay.


----------



## cfcubed

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_How are those Siemens Chrome plates? ECC82? 
 Tried to get them but I keep getting sniped on ebay._

 

Can't decide which is my fav ATM the 63 Siemens ECC82 "chrome plate" or the Amperex 6DJ8 (Holland)... I find the presentation of the Siemens a bit different/exciting where the Amperex has stronger bass. Maybe. 
 BTW May have to go 20-30 USD shipped for the Siemens & maybe 1/2 that for a Amperex 6DJ8 (non-BB). Still keeping an eye out for a BB myself...


----------



## m0b1liz3

How close are we to having the prototype round complete? I am sure there are a few of us in Aus anxious to build one of these.


----------



## ludoo

I'm still waiting for the PCB...


----------



## m0b1liz3

What is the over all dimensions of the case that people are using for this project? Did a page get made for this project on the same site where the SOHA II info was? I remember reading details but don't want to search for them all again.


----------



## wiatrob

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_What is the over all dimensions of the case that people are using for this project? Did a page get made for this project on the same site where the SOHA II info was? I remember reading details but don't want to search for them all again._

 

The Hammond 1455K1202 (or BK) is being used as the standard case. At least one proto'ers is using a longer version of this case.

 As far as searching the thread - I don't wish to sound pedantic, but there's no better way to become familiar with this amp than repetitive exposure 
	

	
	
		
		

		
		
	


	




 Ludoo has provided an excellent resource by extending his great search engine to the compact hybrid thread:

Home / Head-Fi Megathreads


----------



## m0b1liz3

I could have sworn that there was info about his at Cavalli Audio at one point but maybe I was thinking of the SOHA II since I had previously thought about making it.

 Why are some using a long version of the case? Is it to fit a Bantam Dac inside?


----------



## wiatrob

Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_SNIP
 Why are some using a long version of the case? Is it to fit a Bantam Dac inside?_

 

To be able to use RCAs and An RK27 or stepped attenuator.

 EDIT: There's at least one amp in the works this weekend with such a configuration....


----------



## MrSlim

It took a while for my board to arrive too (not as long as Ludo(sorry) but I'm only in Canada), and had some pressing school work I had to attend to, so I wasn't able to get started until yesterday. I'm about half way through populating my board, and want to put in some quality time tomorrow to get it done. I sold my work amp, and have been missing having music at work. With the complexity of the board (over 175 components) and tightness of the components, its critical to take a very methodical approach to building this little beauty. 

 Alex has made the CTH web pages available to the proto crew, but he probably wants to make sure that we help find all the "kinks", as well as adding any build details that we may have discovered. He'll likely wait until the proto phase is over before he releases the CTH web pages.


----------



## holland

It lives. I'm using a Context Engineering case, I need a 1/4" cardboard shim to keep the PCB from sliding front to back, but it still slides side to side about 1/16" (slots are 3" wide exactly). It's mounted in the 3rd from the top slot. Big caps are mounted under the PCB. The 24V reg is mounted underneath to the angle bracket show. I couldn't get the second screw (wiring difficulties mentioned below) in there so I used only the screw closest to the middle of the case.

 I'm using a 120-ohm output resistor on each channel. I mounted it directly to the output jack instead of in the PCB slot.

 Changes from the BOM:
 - different jacks.
 - different switches.
 - different case plenty of room on the front panel for a decent sized knob.

 Snags I hit...
 1) Put C3P in reverse, promptly blew out Q1P and Q2P on power up. Reoriented C3P and replaced Q1P and Q2P and all was good.
 2) Wiring the input jack in the back. PITA! The wire I used is too stiff (Kaptan shielded twisted pair), but would make a good whip. The amount of time to "stuff" the wires into the case was about 30 minutes, that's how much of a PITA it was. I needed extra length so I can pop the panels off as I bottom mounted the 24V reg onto an angle bracket.

 Other than that, all is good. If I ever need to open this again, I'll need to find more flexible wiring for the input jack to pot.

 It's pleasing so far using the EH 12AU7 tube, but too early to really comment. I may switch to RCA 5963 soon. It's still a bit too much gain for high sensitivity low-Z headphones, even with the 120-ohm output resistance. I dare not go over 120-ohm.


----------



## digger945

^C3P-Oh!
	

	
	
		
		

		
		
	


	




(I did that with R2D2 once)
 Great looking case, I like the heatsink(big MacGyver fan).
 Look forward to reading your listening impressions.


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_It lives. I'm using a Context Engineering case, I need a 1/4" cardboard shim to keep the PCB from sliding front to back, but it still slides side to side about 1/16" (slots are 3" wide exactly). 
 < snip >
 I'm using a 120-ohm output resistor on each channel. I mounted it directly to the output jack instead of in the PCB slot.
 < snip >
 It's pleasing so far using the EH 12AU7 tube, but too early to really comment. I may switch to RCA 5963 soon. It's still a bit too much gain for high sensitivity low-Z headphones, even with the 120-ohm output resistance. I dare not go over 120-ohm._

 

Hey, looks good & glad you got it going & like the sound so far...

 Re: case - Yes the 75mm wide PCB is made for cases that take that size... Guess those made for 3" wide PCBs will have a little wiggle.

 I lucked into a 2nd Proto PCB and will be building it in a similar case type, but larger 150mm x 105mm x 55mm (6" x 4.2" x 2.2") enclosure:
Aluminum Project Box Enclousure Case Electronic DIY-Mid - eBay (item 250343308549 end time Mar-14-09 21:01:18 PDT)
 So Alps blue RK27 & all sorts of (internally switched) jacks & RCAs can fit. Will have to get creative w/stand-offs I think
	

	
	
		
		

		
		
	


	




 Plan to bring both of these to the upcoming NYC Spring Meet..

 Re: Gain/output resistor - Those must be some efficient low-Z cans. BTW, technically the output resistor is supposed to be in the OB loop & should be PCB mounted in R18 spots (I'd found it not that big a deal in POC)... And I think runeight has recommended a 150R max.

 Re: tubes - There are a lot to explore... I've tried both an EH 12AU7 & RCA 5963 but so far really like a fleabay BIN Holland Amperex 6dj8 (search "amperex 6dj8 HOLLAND CODE") & the Siemens 63 ECC82 chrome I've talked about.


----------



## runeight

Yes, let me suggest strongly that the series output resistors go on the board in the R18 slots so that they will be inside the output buffer servo loops.


----------



## wiatrob

Nice work Holland! I'vebeen raiding tubes fro my SOHA/SOHAII collection - The 5963 is nice, been giving some bugle boy 6dj8's a chance, and RCA Clear top. Still really like 12BH7s.

 I tried some 12AT's but couldn't get the buffers to stabilize, not so fond of that tube anyhow...


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_but larger 150mm x 105mm x 55mm (6" x 4.2" x 2.2") enclosure:
Aluminum Project Box Enclousure Case Electronic DIY-Mid - eBay (item 250343308549 end time Mar-14-09 21:01:18 PDT)
 So Alps blue RK27 & all sorts of (internally switched) jacks & RCAs can fit. Will have to get creative w/stand-offs I think
	

	
	
		
		

		
		
	


	


_

 

Thanks, cfcubed.

 Interesting case. If you can measure the PCB slots (for potential future stuff), I would guess no more than 1/4" off the bottom.

 There are some corner edge PCB slots out there that can be mounted the case.

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Re: Gain/output resistor - Those must be some efficient low-Z cans. BTW, technically the output resistor is supposed to be in the OB loop & should be PCB mounted in R18 spots (I'd found it not that big a deal in POC)... And I think runeight has recommended a 150R max._

 

I chose 120 for the supposed 120 ohm output resistance of some headphone jacks.

 I tested with a DT440 that I have. My source is @ 2Vrms and the position of the pot is showing the limitations of the RK097 (imbalance) for quieter listening sessions. I suppose I can shunt the pot and drop another 6dB.

 Edit: It's also possible I listen at a lower level?

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Re: tubes - There are a lot to explore... I've tried both an EH 12AU7 & RCA 5963 but so far really like a fleabay BIN Holland Amperex 6dj8 (search "amperex 6dj8 HOLLAND CODE") & the Siemens 63 ECC82 chrome I've talked about._

 

I switched in some RCA 5814s right now. Just looking for tubes I have that are odd man out right now.

  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Yes, let me suggest strongly that the series output resistors go on the board in the R18 slots so that they will be inside the output buffer servo loops. 
	

	
	
		
		

		
		
	


	


_

 

I'm not sure I understand this. Can you elaborate? If in series with the jack, it would be similar to using high-Z cans vs. low-Z cans. I don't understand the differentiation as to whether or not it is within the servo loop.

 Edit:

 One of the reasons I did this is because I've been building my amps with both 120ohm and 0ohm output jacks. Lately I've been using the 120ohm more frequently. I could've socketed R18, but it's in a harder spot to reach, and it seemed easier to put them on the jack for quick replacement.


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I lucked into a 2nd Proto PCB and will be building it in a similar case type, but larger 150mm x 105mm x 55mm (6" x 4.2" x 2.2") enclosure:
Aluminum Project Box Enclousure Case Electronic DIY-Mid - eBay (item 250343308549 end time Mar-14-09 21:01:18 PDT)_

 

 I used the large case for my M^3 - basic and not bad cases. I was thinking about standoff mounted clips/clamps along the edge for the next one of these I might build ( The rumored balanced one. 
	

	
	
		
		

		
		
	


	




). 

 If only there were room for three little mounting holes - that's just how tight this layout is!


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Nice work Holland! I'vebeen raiding tubes fro my SOHA/SOHAII collection - The 5963 is nice, been giving some bugle boy 6dj8's a chance, and RCA Clear top. Still really like 12BH7s.

 I tried some 12AT's but couldn't get the buffers to stabilize, not so fond of that tube anyhow..._

 

Thanks wiatrob. I have a good size stash of tubes from the SOHA 2, so I'm just rummaging through them. It does sound different than the SOHA 2, so far. The sound seems a bit more dense.

 I'm using some RCA 5814a tubes right now. It seems to sound better in this than I recall in my SOHA 2.


----------



## forsakenrider

I keep going back to my Bugle Boy. I dunno what it is, it just seems "smoother" then all the rest. My ears never get tired no matter what Im listening too. Maybe has has to do with the fact that I only have AKG's.....

 Im glad these are getting pumped out! I cant wait for a production board so I can build one for my bro, hes an audio engineer so he should be easy to get into the scene.


----------



## wiatrob

Holland, Who are you sourcing the Context case from?

 I'm off to listen to my Compact Hybrid (thinking 8416), study up on cascode circuits, and drift off to sleep....


----------



## MrSlim

Hey does anyone have a 1/4 inch insulated jack they could spare me? I wanted to get away from using a 1/4 to 1/8 adapter for the CTH and I discovered that there just isn't room for the locking 1/4 Neutrik that I had on hand on the panel after mounting the RCA's and the Blue Velvet. Of course, being the stubborn type and wanting the "all metal" look, I bought the Hammond version with the metal end panels.


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Holland, Who are you sourcing the Context case from?

 I'm off to listen to my Compact Hybrid (thinking 8416), study up on cascode circuits, and drift off to sleep.... 
	

	
	
		
		

		
		
	


	


_

 

Ah cool. I like the 8416 tube very much, but it depends on the headphones.

 I bought the Context Engineering case from Fry's. They have a nicer feel than the Hammond cases, and I use Context Engineering quite a bit. I'm local to Fry's (and Context Engineering, but it's a hassle for them), but frys.com sells it and so does Circuit Specialists. The prices are the same for frys.com and in store. I'm not sure what the shipping to CO would be.


----------



## wiatrob

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Ah cool. I like the 8416 tube very much, but it depends on the headphones.

 I bought the Context Engineering case from Fry's. ... I'm not sure what the shipping to CO would be._

 

Thanks. I get to Major Urban Areas with Fry's a bit


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Thanks. I get to Major Urban Areas with Fry's a bit 
	

	
	
		
		

		
		
	


	


_

 

When you buy the cases, make sure it has a little package inside. It contains the screws for the other end of the panel, and that both panels are screwed onto one end. The cases are in a plastic wrap. Sometimes people open them up to size things or returns.

 Fry's is notorious for half-opened or returned stuff.


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Thanks, cfcubed.
 Interesting case. If you can measure the PCB slots (for potential future stuff), I would guess no more than 1/4" off the bottom._

 

Yes, as waitrob indicated they seem darn nice cases esp. for the price... There's a bigger one (& they come in black too). Got mine fast:





 It's about twice the volume of the target case for this project, but I have plans
	

	
	
		
		

		
		
	


	




 True, has only the two PCB slots centered 3/16" (4mm) off top/bottom. My slots are exactly 100mm (3-15/16") wide so probably takes 98mm-100mm wide PCB.


----------



## holland

wow, that material looks *thick*. very nice.


----------



## wiatrob

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_wow, that material looks *thick*. very nice._

 

OT: here's some pics of the larger case:http://www.head-fi.org/forums/f6/pos...ml#post5463013

 Probably fit three CH's in there


----------



## holland

Using the Amperex 6189 tube. I disliked this tube on my SOHA 2 as it was somewhat odd sounding, but it seems to fare well in this amp.

 Overall I'm getting more impressed with this amp. I haven't come across anything that has a weird presentation. Good job, cfcubed and runeight.


----------



## TimJo

I posted this over at the prototype builder's thread, but I thought I'd update the Head-Fi gang as well.

 I finally had enough free time yesterday to work on this beauty of an amp. I got the board populated and did the preliminary start up to check voltages. I'm happy to report that everything checked out first try and now I'm ready to move on to wiring and casing it (hopefully tonight after work).

 My advice to anyone attempting the build is to work slowly and methodically, and it is a no brainer. The key here is to check and double check everything as you go, looking for solder bridges along the way, because things can get pretty crowded in their, depending on your layout.

 My build is slightly different then the 'stock' build because I decided to try mounting all of the taller components under the board, in order to allow the tube to be fully exposed outside of the case. This worked out fine, and am looking forward to getting it inside of the enclosure to verify that it all fits as planned.

 A couple things to note - I decided to switch the positions of the leds. I did this with the idea that green means it is powered up, and orange means it is 'warmed up' and ready for music - plus if any light is sneaking out of the enclosure, I prefer a orange glow as opposed to to green. The other thing is the led's I used are kinda oversized for this board, but they were gathering dust in a parts box, so I used them rather than buying new ones. Also, I like to live dangerously and chose to skip both a switch and a fuse, so S1 - S2 is jumpered with a zero ohm resistor. I wouldn't recommend this in general, unless you fully understand the risks...

 The BOM is pretty much stock with the exception of substituting Nichicon elctrolytic caps for the Xicons, and pretty much all WIMAs on the films. I used some Vit Q's I had lying around for the bypass positions as well.

 With the tube outside of the enclosure, my hope is that the only big heat producer is the voltage regulator, and there will be enough airflow based on this layout to keep it in limits using the BOM heatsink. I chose to mount it under the board with the pins bent at 90 degrees, and the heatsink pointing down. I'm banking on the notion that the heater reg will stay cool enough without a heatsink based on convection airflow. We'll see once she's boxed up...

 Here are a few teaser pics from last night...


----------



## holland

Cool, TimJo. I did the same thing with my build. I thought about chopping off the tab of the LM2595 entirely as I didn't want it scraping the top of of the case even after it's bent back or forward as in your picture, not that it would be a bad thing entirely. I couldn't bend it as far as you did. That's when I decided to mount it underneath. I had to bend the legs, but it fit underneath just fine as well. It's a pain to desolder it when mounted underneath as it's very close to some plastic caps.


----------



## cfcubed

Yes, cool indeed TimJo... I wonder what case you are targeting. You can make that a surprise
	

	
	
		
		

		
		
	


	




 True about the checking/double-checking joints, parts & polarity. I _think_ we may be at the stage where the design, BoM & PCB are fairly proofed. Having one std build, I'm now also going for a deviation/non-std build... And its only happening because I'm very happy with the 1st build
	

	
	
		
		

		
		
	


	




 When production rolls around it will be interesting to see how many do a std build (e.g. target case) and how many a non-std build. 
 BTW I think I'm going to resort to trickery for PCB mounting in my non-std case (proto PCB has no mounting holes)... Going take a perfectly good very small hammond enclosure & cut it into 4 pieces (lengthwise along middle sides + top & bottom) to create nice mountable PCB edge brackets. We'll see. Maybe I'll poke around for other ideas...

 Well good luck & I'm sure you'll let us know how it turns out.


----------



## ludoo

I got my PCB today, and the Mouser order finally came too after I managed to "unstuck" it as the heater switch changed from available to backordered in the space from checking out and paying, and Mouser kept quiet until I started wondering why my stuff did not show up.

 But, the 88 euros order came with a customs bill attached for 38 euros, which is unbelievably expensive and totally wrong (note that I did not have to pay any duties on previous orders). I spoke with FedEx, and apparently they used the USD amount to calculate customs duties in euros, so I filed a claim and now I'll have to wait for it to be checked before getting my stuff. Bah, maybe next time I should only participate to a proto build if I can source everything from the EU. Sorry for all this, people.


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_When production rolls around it will be interesting to see how many do a std build (e.g. target case) and how many a non-std build._

 

I think it might depend on whether or not there are pre-drilled panels, etc.

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_BTW I think I'm going to resort to trickery for PCB mounting in my non-std case (proto PCB has no mounting holes)... Going take a perfectly good very small hammond enclosure & cut it into 4 pieces (lengthwise along middle sides + top & bottom) to create nice mountable PCB edge brackets._

 

Interesting. How will they be reattached?


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Interesting. How will they be reattached?_

 

The little cut up hammond would create 4 identical L-shaped pieces... The short side of the L having the PCB slots. The long side would get through holes for screws that thread into the (very thick) bottom of that ebay case (using 6/32" drill/tap set), possibly with stand-offs to bring PCB up close to case top. CTH PCB would be centered width-wise & up against the back panel of the case, allowing for 3 PCB edge bracket/contact points (front + sides). 
 Again, we'll see if I come up w/something better, easier, cheaper, etc. If I don't I'll post pics.

 ludoo - Sorry for your shipping difficulties! Good luck.


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_The little cut up hammond would create 4 identical L-shaped pieces... The short side of the L having the PCB slots.._

 

You might also investigate hobby aluminum channel stock, might save you some cutting... Train store nearby??


----------



## wiatrob

Quote:


  Originally Posted by *ludoo* /img/forum/go_quote.gif 
_...Sorry for all this, people._

 

No need to apologize, your expereince is totally 'bogus' as we say over here!!

 Take some solace in the fact that the build sounds quite good when it comes together. Driving my Lambdas as loud as I'd like them right now...


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Again, we'll see if I come up w/something better, easier, cheaper, etc. If I don't I'll post pics._

 

Interesting, but I would probably go for this.

Edge Support PCB Spacer, UB-6F Manufacturer -- PINGOOD ENTERPRISE CO., LTD. is a leading supplier and exporter of Edge Support PCB Spacer, UB-6F in Taiwan, Asia
PCB Spacer Support / PCB standoff / Circuit board spacer / Edge support Manufacturer -- PINGOOD ENTERPRISE CO., LTD. is a leading supplier and exporter of PCB Spacer Support / PCB standoff / Circuit board spacer / Edge support in Taiwan, Asia
Edge Support, UB-09K Manufacturer -- PINGOOD ENTERPRISE CO., LTD. is a leading supplier and exporter of Edge Support, UB-09K in Taiwan, Asia

 a good series of them along the edges will do well, IMO.

 with these for support

PCB Spacer Support / PCB standoff / Circuit board spacer Manufacturer -- PINGOOD ENTERPRISE CO., LTD. is a leading supplier and exporter of PCB Spacer Support / PCB standoff / Circuit board spacer in Taiwan, Asia
PCB Spacer Support / PCB standoff / Circuit board spacer Manufacturer -- PINGOOD ENTERPRISE CO., LTD. is a leading supplier and exporter of PCB Spacer Support / PCB standoff / Circuit board spacer in Taiwan, Asia

 I actually was going to use this, and make the amp bigger to fit the transformer in the same case with different offboard voltage regulation, before I decided on the Context Engineering case and the external AC transformer. The charm of something small won over the desire to overkill everything these days (Tim Allen syndrome).


----------



## MrSlim

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_. Going take a perfectly good very small hammond enclosure & cut it into 4 pieces (lengthwise along middle sides + top & bottom) to create nice mountable PCB edge brackets. ._

 

Hey, I was thinking about an idea to put two of these in a Hammond 1455T1601 case, which is just over twice as wide and then using 2 or 3 bolts with either nylon spacers or nuts adjusted for the right height to be used as the "slot" in the middle, bolted up through from the bottom..

 It might be a fun balanced amp..


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_No need to apologize, your expereince is totally 'bogus' as we say over here!!

 Take some solace in the fact that the build sounds quite good when it comes together. Driving my Lambdas as loud as I'd like them right now..._

 

How much power does it put out?


----------



## holland

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_It might be a fun balanced amp.. 
	

	
	
		
		

		
		
	


	


_

 

Indeed.


----------



## runeight

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_How much power does it put out?_

 

The buffers can get to about 1V of their rails which would be 11V peak.

 For 32R this would be 121 / (2* 32) = 1.9W.

 But this is not practical because the amp will be limited by the current sourcing capabilities of the PS. Let's arbitrarily say we can get a maximum of 100mA peak from the PS. We can actually get more, but let's not get greedy.

 Then for 32R we have 100mA * 100mA * 32 / 2 = 160mW RMS power.

 For 300R we have 121 / (2* 300) = 200mW RMS

 These are rough numbers that will vary some from component variations, how well the rail splitter splits 24V to exactly 12V/12V, etc.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_How much power does it put out?_

 

Technially, the amp was driving the SRD7, driving the lambdas


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Technially, the amp was driving the SRD7, driving the lambdas 
	

	
	
		
		

		
		
	


	


_

 

So, how do you get enough power output to drive the SRD-7 SB?


----------



## m0b1liz3

Are we getting close to this being ready as a kit yet 
	

	
	
		
		

		
		
	


	




????


----------



## nsx_23

X2 on the kit.


----------



## olblueyez

Kit please!


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_So, how do you get enough power output to drive the SRD-7 SB?_

 


 Not knowing that this amp is underpowered for driving a 'stat energiser, I just went ahead and plugged it in. I haven't heard it head to head with more powerful amps yet, the stats just made it home from work...

 Probably would benefit from more juice - But it didn't sound too slouchy...


----------



## Sancho86

No need for a kit for me, a PCB will be fantastic


----------



## cfcubed

First wanted to say that very early on I envisioned a small tube amp that delivered desktop-class performance that could be toted around. Talked about that way back in the 2nd post.

 We see that it appears to meet the performance goals & here it is meeting the briefcase one:





 And this shows why the std design w/recessed tube is something to consider. With about 1/2 the tube below decks the set up is secure enough to travel w/o removing the tube. Been doing this for a week or so & it's all good (std slim briefcase - about 3-1/2" thick). Just make sure your build is secure (no loose solder, metal bits & good solder joints, etc.)

*Kits* - Runeight, being very conservative & careful with _your_ time and resources, will likely do a "roll call" across the proto builders soon and assess this. Clearly all signs point to good things here.

 "_*Probably would benefit from more juice*_" - Don't know much about balanced bit but would 2 PCBs in balanced config get what is needed? *BTW, could someone point me (PM) to good information on the benefits of balance config w/dynamics?*

*PCB edge mounts* - Thanks for the links holland & alum stock suggestion waitrob... Would like to stick w/metal (I like metal
	

	
	
		
		

		
		
	


	




) & have the $12 little hammond on the way so we'll see. My saws-all w/metal blade would make quick work of things... Love getting destructive w/that thing


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_First wanted to say that very early on I envisioned a small tube amp that delivered desktop-class performance that could be toted around._

 

I absolutely agree. For a transportable that is not a pure portable (mini3 territory), I think this is a *very* nice amp.

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_With about 1/2 the tube below decks the set up is secure enough to travel w/o removing the tube._

 

I don't think it's too difficult to remove the tube. 
	

	
	
		
		

		
		
	


	




 After all the work in building and designing the amp, removing the tube is too much? 
	

	
	
		
		

		
		
	


	







 I'm just being a PITA. 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_*Kits* - Runeight, being very conservative & careful with your time and resources, will likely do a "roll call" across the proto builders soon and assess this. Clearly all signs point to good things here._

 

I think there should be a limited run of panels and belly plates. My panel work (IMO) really sucked as the top hole is off a bit and just ticks me off when I look at the tube off center. I might go for it too, as I want to build a few of these as gifts. I just hope we could find a good pot (RK27 class) in RK097 form factor. That would just make my day, cause the RK097 is not so good with tracking, albeit better than others I have encountered in that size range (alpha pots, etc.).


  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Don't know much about balanced bit but would 2 PCBs in balanced config get what is needed?_

 

I doubt it, but I can't say with certainty. The Stax SRD-7 energizer is made for power amps, and IIRC has an internal 24:1 transformer (assume 8ohm input) to convert power amp voltage and current to Stax voltage and current.

 The guys working on the electrostatic amp may be able to back calculate the required voltage/current for Stax headphones, apply it through the transformer in the SRD-7 to see how much power is really necessary.

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Would like to stick w/metal (I like metal
	

	
	
		
		

		
		
	


	




) & have the $12 little hammond on the way so we'll see._

 

You're welcome. The context engineering case I used is only $14 and saves you 1 cut as it's a split case.


----------



## TimJo

An update on my amp - last night I got the inputs and outputs wired, and some of the casework finished (well, enough to listen to it anyway 
	

	
	
		
		

		
		
	


	




).

 All I can say is I stayed up 'till 1:30 in the morning listening, because I just didn't want to stop - this is a good sign of a great amp in my book.

 I have only listened using a GE 5814 black plate and my DT880's so far. I've four other tubes sitting there just waiting for a turn, so I'm excited to oblige and let them have a run at it...

 I'm hoping to get the rest of the casework and the heater switch installed tonight, and then I'll post some photos.

 Here's a sneak peak in the meantime...


----------



## cfcubed

Quote:


  Originally Posted by *TimJo* /img/forum/go_quote.gif 
_< snip >
 All I can say is I stayed up 'till 1:30 in the morning listening, because I just didn't want to stop - this is a good sign of a great amp in my book._

 

Very nice looking amp. Great too that it didn't disappoint WRT SQ
	

	
	
		
		

		
		
	


	




 I too had a hard time walking away when I 1st heard mine. Think this amp will make waves. Seems all the tubes I tried are "happy" in this amp & the "honored" tubes (Amperex, Siemens, BBs) live up to their reps too.

*holland - WRT tubes/holes* - I know I posted somewhere about how tube ring / protectors save my butt WRT tube hole centering (from vtc, ebay). I use 1 ring of the 3 in my builds & they mask most any off-center tube hole
	

	
	
		
		

		
		
	


	



 Yes, removing the tube is no problem either. Just like one less step in transport
	

	
	
		
		

		
		
	


	



 Oh & yes an even better pot than the RK097 that fits in target case would be nice. Don't know if the BoM alt panny EVJ (digikey: P2G1203-ND) is any better...


----------



## holland

TimJo, wow that tube hole is very tightly packed in there. You must have spent an awful lot of time measuring. Any tips you want to share? 
	

	
	
		
		

		
			





 I wanted the tube hole bigger to let some heat escape, as I have vent holes in the bottom as well. It still does get too warm (IMO) and I may have to open up more holes on top.

 cfcubed, yep I remember those protectors. I thought about using them, but since I mounted the PCB in the top slot, and the caps are right on the case, I don't think I have room for nuts on the underside. Unfortunate, but true.

 What is your source level output range? Mine is ~2Vrms max. I'm using my DT150 @ work which is 250 ohms right now (my other headphones like ATH-M50 or M-Audio Q40 are much more sensitive), and I can't get the knob to 9 o'clock with the "loudness enhanced" recordings of today. The RK097 seems to noticeably break up between 7-8 o'clock. I have to turn down my source. I'm using a 12AU7 variant (6189) with 120 ohm series resistors. Perhaps populating them in R18 affects the output signal more?


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_ < snip > yep I remember those protectors. I thought about using them, but since I mounted the PCB in the top slot, and the caps are right on the case, I don't think I have room for nuts on the underside. Unfortunate, but true._

 

If the top panel is thick enough I'd consider just drill/tap it & use short screws for the tube ring, thus nothing pokes below top panel (cut off screws to fit). If you've no taps just buy a single tap kit (e.g. 6/32 - has correct bit + tap) & use a drill on slow to drive the tap. Something to consider...

  Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_What is your source level output range? Mine is ~2Vrms max. I'm using my DT150 @ work which is 250 ohms right now (my other headphones like ATH-M50 or M-Audio Q40 are much more sensitive), and I can't get the knob to 9 o'clock with the "loudness enhanced" recordings of today. The RK097 seems to noticeably break up between 7-8 o'clock. < snip >_

 

Shoot! I forgot that I "mp3gain - album normalize" all my files to 90db.... This could explain why its less of an issue for me... That process kicks down the volume uniformly to mitigate horrible effects of the "loudness war". I use like 225kbs/VBR/Stero MP3s.
 Alex knows best WRT using R18s for output resistors


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_If the top panel is thick enough I'd consider just drill/tap it & use short screws for the tube ring, thus nothing pokes below top panel (cut off screws to fit)_

 

Good idea! I'm glad you thought of it for me. 
	

	
	
		
		

		
		
	


	



 The CE cases are not as thick as Hammond belly plates, but should be thick enough to use a 1/8" screw with small protrusion.


----------



## nux

This looks excellent, love the design. I'm looking forward to building one or two once its all finalised.

 Will the PCB gerber files be made available at all? I can get them fab'd quite cheaply locally and could make some available to other Australian's wanting to make it.


----------



## TimJo

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_TimJo, wow that tube hole is very tightly packed in there. You must have spent an awful lot of time measuring. Any tips you want to share? 
	

	
	
		
		

		
		
	


	


_

 

Well, I think you hit it on the head. _Careful measuring_ and I tend to move up drill sizes slowly. After centerpunching, I usually start with a 1/16 bit, and then move up in sizes a little at a time allowing each subsequent pass to center itself in the prior hole. Once I hit 1/4" then I use a stepped bit which keeps things centered as well. That being said, it also is dependent on how my luck is running - sometimes it doesn't work out perfectly. Luck was on my side on that tube hole.


----------



## digger945

I've had fairly good results with the Irwin Unibit step bit. It seems to be a bit more ridgid and doesn't flex like the smaller bits, and thus stays centered a little better. I am using them on a small table top drill press. I still punch the metal to get things started. I want to shop for a press with less slack to keep the bit from wandering, and now I lower the bit and put a fair amount of pressure then flip the power on.


----------



## TimJo

Okay, she's all finished now !!! 
	

	
	
		
		

		
		
	


	




 I am loving this amp and so far I am really digging the sound. The thing is so small and easy to move around I'm blown away that it sounds this good. The amp is dead quiet, with only a little hiss when the pot is maxed. One thing I have noticed is that the volume can be a bit louder than I am used to, but with no fatigue, just more detail with amazing control. It is probably just that I am so used to the Millet tubes that I am experiencing the benefits of higher end audio tubes for the first time, and I am liking it. The servos are great as well because it means rolling tubes is so easy. Last night (and right now) I'm trying out a CBS 7730 (gold pins and black plates) and the results are quite good. 

 I used the longer Hammond case so I could fit a Blue Velvet pot, and I mounted the taller components on the bottom of the board. Several of the 1" caps were just a little too tall to fit in the case, so I drilled some holes in the bottom plate. I also added a 4-40 screw under the tube socket before soldering so that I could have a standoff between the board and the bottom plate. The tube socket is in contact with the top, and the standoff supports the board underneath, so there is no flexing to the board when rolling tubes in or out. I added four holes directly below the voltage regulator, and a row of 'exit vent' holes along the top of the back panel. The case is barely warm with only this minimal venting - largely because the tube itself is completely out of the case.

 Here are a few pictures of the amp. I added one next to my iPhone for an idea of how small this thing really is...


----------



## digger945

That's sharp. I really like it. You've obviously done this before


----------



## Giuss

Are schematic and project details avaiable?


----------



## wiatrob

Quote:


  Originally Posted by *Giuss* /img/forum/go_quote.gif 
_Are schematic and project details avaiable?_

 

Details will likely be available soon - after the rest of the prototype builds are finished and feedback incorporated.


----------



## MrSlim

The second round of 10 proto boards are getting near to being completed. It will be up to Runeight to decide when he's ready to take it to the next phase. He and Cfcubed have done a great job on it, and most of the issues that have come up were self inflicted. Runeight has a great web resource that he will make available when he's ready. Full schematics will probably not be made available, after he got burnt on the SOHA project. He's broken it up into sections that can be used for diagnosis, but not for replicating the full board..


----------



## sachu

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_The second round of 10 proto boards are getting near to being completed. It will be up to Runeight to decide when he's ready to take it to the next phase. He and Cfcubed have done a great job on it, and most of the issues that have come up were self inflicted. Runeight has a great web resource that he will make available when he's ready. Full schematics will probably not be made available, after he got burnt on the SOHA project. He's broken it up into sections that can be used for diagnosis, but not for replicating the full board.._

 

Second round?

 I thought our boards were the first round?..I would be interested in picking up one more board if anyone is not using theirs..


----------



## runeight

They were. There are no boards currently available. We are working on this. Getting more boards is easy, but supporting kits is a little harder.


----------



## sachu

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_They were. There are no boards currently available. We are working on this. Getting more boards is easy, but supporting kits is a little harder._

 

right..i understand..however, i seem to have most of the parts with me now..so whenever the more boards become I would be happy pick one up..this amp is soo good..I love it..my first tube amp ever.

 can't wait to show it off at the upcoming meet here in Portland..


----------



## nux

Is the BOM looking like it can all be sourced from Mouser?

 And would it be possible to be PM'd a copy of the BOM? I'm just finalising a large Mouser order for some other projects, and it would be great if I could add the parts required for this to be ready for when PCB's are available, as shipping to Australia is expensive 
	

	
	
		
		

		
		
	


	




 Anyway the design looks great, very well thought out. Looking forward to building one.


----------



## nsx_23

^ You might like to wait for a kit. Several of us Aussies seem to be interested in building one as well.


----------



## MrSlim

Sachu, I called us the second round, since Cfcubed and Forsakenrider actually had them in their hands first and built up the first pair of boards before Runeight sent them out to us. Or we're phase 2 of round 1..


----------



## dracoV

I agree we should wait for the final design to come out first, before ordering any parts.
 Since it may have few changes. (as eager to build it as I do now, I still rather wait 
	

	
	
		
		

		
		
	


	




 )
 As I recalled, mentioned in a couple pages earlier, 
 there's a little hick in buffer servo mechanism which runeight already solved the problem.
 That may yield a little change, I believe.

 For the proto team, anyone have access to some test equipments.
 Can you do some measurements? may be we can fine tune a little bit
 for the final design.

 For example, perhaps consolidation of those 2.X k resistor to one or two values, so
 there will be no need to order many unused parts. (I tend to order resister in a pack of 
 multiple ten 
	

	
	
		
		

		
		
	


	




 )

 Cheers,


----------



## MrSlim

DracoV, I have to say, that is the beauty of ordering from Mouser.. They will sell you a single resistor of a certain value. Notwithstanding their BOM tool.. No more tedious entry of 170 odd parts.. Now, if they would ship as fast and a cheaply as Digikey.. then I'd be Happy.. (Digikey will ship to Canada overnight for $8.. Mouser charges $20 for 1-2 day service..) I've ordered as late as 5 pm from Digikey and it shows up at my office by 10ish the next day..


----------



## sachu

This is great that almost all the amps are now functional...a few hiccups along the way but everything seems to be working out... haven't been able to finish up the case just yet...by saturday for sure..back to listening to the 12BH7A now..


----------



## wiatrob

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Is the BOM looking like it can all be sourced from Mouser?_

 

There are still two parts from Digi-Key AFAIK... 

 My amp has been running for just about a month now with no issues. It was one of the second round of 'proto' builds - if you don't count the Proof of Concept - an incredible build by CFCubed.


----------



## cfcubed

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Is the BOM looking like it can all be sourced from Mouser?
 < snip >
 Anyway the design looks great, very well thought out. Looking forward to building one._

 

Check out this post for alternative Aussie source for the 2 Digikey parts. Think some sort of PCB/parts assistance should happen by month-end. Perhaps a mini bundle w/PCB, LM2595 & 220uH coil? Think we'll know pretty soon.

 Thanks from runeight & I for the kudos WRT the amp, etc. It is certainly looking like a successful prototype process & things are quite solid now.
_My opinion_ is that this is an intermediate level project... Nothing to bias, match & no options (other than clear or black alum
	

	
	
		
		

		
		
	


	




) but even experienced builders can make one or two mistakes across the 160 or so parts. As sachu says it looks like even those few builders will have working amps very soon (one remaining? thanks to runeight for that).

 There is a lot of info on the draft CTH website & there will be even more to assist others & help them further to put the rights parts in the right places (& w/correct polarity). That's all it takes. And all feedback indicates it's well worth the effort


----------



## zkool448

Awesome and sounds like a perfect project next... I've not done a pcb and have always wanted to. I was looking to build a SOHA II but after seeing all the tweaks, biasing methods, and all the tech jargons being thrown around I thought it was way over my head -- seeing this CHT coming to life sounds like the ideal starting point.


----------



## MrSlim

As we all have discovered, if one is diligent in reading the provided information 
	

	
	
		
		

		
		
	


	




, and being careful about part placement, the CTH can come together pretty nicely. And with the dual heater voltage, and servo adjustment for the plate voltages, tube rolling is going to be a dream.. 
 I've already ordered my third tube, just from some of the other guys recommendations. 

 And one very positive thing, the tubes are very very available, unlike the SS tubes, which are getting hard to find and more expensive all the time. I was going to build one for a friend, but had to re-consider once I found out how much it was really going to cost.. He's not THAT good a friend..


----------



## dBel84

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_can't wait to show it off at the upcoming meet here in Portland.. 
	

	
	
		
		

		
		
	


	


_

 

 This will be a new experience for me 
	

	
	
		
		

		
		
	


	




 = hearing a Cavalli build not built by myself 
	

	
	
		
		

		
		
	


	




 I look forward to it..dB


----------



## forsakenrider

I want to show mine off!! I need to meet some headfiers around here, or make some out of my buds! 
 I have tooooo many tubes to roll through this, I dont know what Im going to do....


----------



## olblueyez

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_I want to show mine off!! I need to meet some headfiers around here, or make some out of my buds! 
 I have tooooo many tubes to roll through this, I dont know what Im going to do...._

 

Smoke another one and come up with another super duper intellectually stimulating and funny post that eludes everyone not in the know.


----------



## cfcubed

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Smoke another one and come up with another super duper intellectually stimulating and funny post that eludes everyone not in the know. 
	

	
	
		
		

		
		
	


	


_

 

Heh. I don't get that post at all. My only guess is that it _could_ be frustrating that after hearing the good stuff about this amp access to PCBs/kits is not available at the moment? *Edit - Ha. Just read your sig... Maybe you are just being sarcastic & that was a joke? Hope so
	

	
	
		
		

		
		
	


	


*

 Please be aware runeight & I are working hard to make PCBs and/or kits available as soon after the proto stage is vetted as possible. Think we've shared everything here that makes sense until the proto PCB round is over (any day now?). Wouldn't want people, other than the proto "guinea pigs", to suffer through any bumps in the road to a fine working amp. Only through responsible diligence (e.g. fine design work, sims, protos) can solid, hassle-free designs come about. 

 Being a "Headphoneus Supremus" I'm sure you've perused various forums (& threads in this very forum) enough to see the growing pains in other protos & even "production" projects that can be avoided through the above (e.g. not rushing things out). 

 Edit: Realize too it may be hard for prototypers of this amp (that have not heard amps of this caliber) to contain their excitement & satisfaction with it. I'm guilty of doing that here (sorry, but its nice when something works out as hoped). Again PCBs and/or kits will be (responsibly) available soon.


----------



## runeight

Quote:


  Originally Posted by *forsakenrider* /img/forum/go_quote.gif 
_I want to show mine off!! I need to meet some headfiers around here, or make some out of my buds! 
 I have tooooo many tubes to roll through this, I dont know what Im going to do...._

 

Not to speak for forsakenrider, but I thought he was referring to the fact that other CTH prototypers are taking their amps to meets in the near future and that he would like to have an opportunity to do that too.


----------



## forsakenrider

Well done runeight, at least one person gets me 'round here.

 Right now ive got a sovtek 6922 in there, never heard one of these variants before.... so far so good, needs more time though. Its not jumping out anywhere specific though..


----------



## TimJo

I have to say that one of things I'm loving about this amp is the fact that it so small. I'd have no problems or worries about removing the tube and throwing the amp in my backpack. Over the last couple of days I've been moving it around from place to place depending on where I'm going to listen, and the portability is outstanding.

 I'm also really enjoying rolling tubes - I'm on to trying out a third tube now - an Amprex 8416.


----------



## holland

nice tube. it mates well with the beyer premium line.


----------



## sachu

A few pics of my build..

 Need to still drill a hole for the tube on the top plate..




















 Top toggle switch is for amp turn on and off..lower toggle switch is for heater voltage selection


----------



## wiatrob

Nicely done! 
	

	
	
		
		

		
			





 Take your time with the tube hole and you'll nail it on center...


----------



## nux

To get more output power to drive low-Z headphones and small 8ohm speakers to ~0.25W, would it just be a case of changing the BC327/337 output transistors for larger power transistors (perhaps also a larger walwart)?


----------



## MrSlim

nux, Changing the transistors on the output and the walwart isn't the only thing you would have to change. The walwart specified in the design is around 800mA, but in a previous message posted here, runeight suggests that the ouput of the power supply would be around 100mA, which is perfectly fine for use in a headphone amp. If you tried to hook up 8ohm speakers to this amplifier, it would probably only put out about 40mW of power, which is a factor of 6 lower than what you are looking for. 

 Using Runeight's math in reverse where X is the output current of the power supply for you to get .25 w into an 8ohm speaker : X*X*8/2=.25 watts. X*X=.0625
 The square root of .625 = .250A or 250mA, which is 2 1/2 times larger that the typical 100 mA he is suggesting the power supply is capable of. 

 Start thinking about all the components you are going to have to change and it turns into a different amplfier, in a different form factor. 

 Sorry for the rant, but I guess I don't get why people want to run speakers with a headphone amp.. Why not buy one of these: ClassT T-AMP TA2024 Audio Amplifier Board SMT 2X15 Watt - eBay (item 230329799289 end time Mar-10-09 18:25:20 PDT) 
 for $20, and you could put it in a little box beside your lovely little CTH and have a switchbox on the input to choose which unit you want to listen to. Or put the both together in a bigger box, with a built in switch..


----------



## nux

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_nux, Changing the transistors on the output and the walwart isn't the only thing you would have to change._

 

Firstly, I realise I may be rude in asking how to modify this somewhat drastically to do another purpose than what it was first intended, especially when it is not fully completed. So I apologies if that is the case, and please let me know if I should be asking this elsewhere.

 But I am very keen on making a small tube amplifier capable of driving headphones or a small pair of speakers, and this design looks perfect for that. I realise I will have to modify it a fair bit, and probably use a separate PCB for the output buffer, but thats half the fun (this is DIY after all!).

 I gather a 1A 24V regulator is being used, so that should be enough even for 1W output power (with a proper heatsink). The only things holding it back are the BC327/337 on the output buffer and virtual ground sections from what I can see.. Any feedback appreciated. And I didn't take your comments as a rant, I guess I'm just asking if I'm on the right track in how to modify this from a headphone amp to a small general purpose low power TUBE amp


----------



## m0b1liz3

"Why not buy one of these: ClassT T-AMP TA2024 Audio Amplifier Board SMT 2X15 Watt - eBay (item 230329799289 end time Mar-10-09 18:25:20 PDT"

 Wow, building my 41hz amp feels like a waste of time now! I am tempted to order one just to see how good it is in comparison.

 BTW Nux, MrSlim is right. I had a similar idea to you but realized that it wasn't worth it in the end after pricing out the difference in required transformers etc.. You could figure out how to use the HP amp as a preamp though and run it through a class t amp like the one above. The S.E.X. amp from Bottlehead does what you want. Transformers are what can really drive the costs on such projects. It is too bad they cost so much because I would have built multiple guitar amps by now otherwise.


----------



## MrSlim

mOb1liz3, 
 I'm part way through building a Amp6 myself.. the board is done, just need to get a heatsink and case it up. That was my thought exactly though, it sure looks like an interesting idea. Only, they didn't exist a year ago when I bought the stuff originally (or longer.. shesh) . I saved a thread somewhere on doing Mod's to it also.. 

 Edit: There is a Blog of one person's work here: http://finetone.blogspot.com/2008/10...r-further.html

 Edit2: The thread on the board: http://www.diyaudio.com/forums/showt...5&pagenumber=1


----------



## cfcubed

Quote:


  Originally Posted by *TimJo* /img/forum/go_quote.gif 
_ < snip > I'm also really enjoying rolling tubes - I'm on to trying out a third tube now - an [Amperex] 8416._

 

When a way for others to build this amp comes about, perhaps as soon as month's end, think a dedicated tube thread for this amp would be helpful. Since it seems that production PCB/BoM will not deviate electronically from about mid-proto process, tube impressions will not differ between proto/prod.

 There will be various synergies (e.g. tubes w/given cans), house sounds, etc. I'm finding my Amperex BB 6dj8 *very* similar to the $7.50 USD ebay std Amperex 6dj8 white-label I've mentioned (Edit: Both of which I love even tho D2000s already have plenty bass). And I wonder if their 8416s, 12au7s, etc are notably different sounding. 

  Quote:


  Originally Posted by *m0b1liz3* /img/forum/go_quote.gif 
_"Why not buy one of these: ClassT T-AMP TA2024 Audio Amplifier Board SMT 2X15 Watt - eBay (item 230329799289 end time Mar-10-09 18:25:20 PDT" ....
 Wow, building my 41hz amp feels like a waste of time now! I am tempted to order one just to see how good it is in comparison._

 

Ha ha... I'm thinking the same & I need _another_ speaker amp like a hole in the head. Better for another thread but perhaps using this headamp w/some source switching, etc. as a pre is not that far off base... It does have muting delay + offset protection.
 Also better for another thread, but maybe this or this are t-amp mod threads MrSlim was thinking of...


----------



## runeight

You know, I shouldn't even mention this, but it would not be hard to make a speaker amp version of this amp. It would be quite a bit bigger and a 1A wall wart would be absolute minimum. There would be more heat burned inside the box and a serious regulator heatsink would be necessary.

 But the rest could be done without much difficulty on a bigger board.


----------



## MrSlim

Ha, now the Cat is out of the Bag..


----------



## cfcubed

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Ha, now the Cat is out of the Bag.._

 

Maybe Cat*s* over time... The balanced itch could get scratched 1st, who knows? First things first tho.


----------



## sachu

how about a prototype of that once this has settled down..I would be willing to sign up for one of those boards if at all you guys go ahead with it...


----------



## TimJo

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_When a way for others to build this amp comes about, perhaps as soon as month's end, think a dedicated tube thread for this amp would be helpful. Since it seems that production PCB/BoM will not deviate electronically from about mid-proto process, tube impressions will not differ between proto/prod.

 There will be various synergies (e.g. tubes w/given cans), house sounds, etc. I'm finding my Amperex BB 6dj8 *very* similar to the $7.50 USD ebay std Amperex 6dj8 white-label I've mentioned (Edit: Both of which I love even tho D2000s already have plenty bass). And I wonder if their 8416s, 12au7s, etc are notably different sounding._

 

Agreed. Besides the portability (which is what really makes this amp shine in my book) the tube rolling is turning out to be a lot of fun. This morning I am trying out an RCA 6189 (black plates, triple mica, square getter) manufactured in '58. I'm liking what I am hearing so far, but only an hour out of the box after sitting around for fifty years, I know it has yet to reveal itself. It's like letting a genie out of the lamp...


----------



## mypasswordis

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_You know, I shouldn't even mention this, but it would not be hard to make a speaker amp version of this amp. It would be quite a bit bigger and a 1A wall wart would be absolute minimum. There would be more heat burned inside the box and a serious regulator heatsink would be necessary.

 But the rest could be done without much difficulty on a bigger board._

 

Yes, please.
	

	
	
		
		

		
			





 I'm a fan of moar power so that I can drive my orthos and maybe even my Stax through the transformer boxes properly.


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_ And I wonder if their 8416s, 12au7s, etc are notably different sounding._

 

I have the Amperex PQ 8416 and the Amperex "orange globe" 6189. They are very different sounding.

 I am very much enjoying the Du Mont 5814a (RCA rebrand) with my DT150.


----------



## holland

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_You know, I shouldn't even mention this, but it would not be hard to make a speaker amp version of this amp. It would be quite a bit bigger and a 1A wall wart would be absolute minimum. There would be more heat burned inside the box and a serious regulator heatsink would be necessary.

 But the rest could be done without much difficulty on a bigger board._

 

Then I would request a low-mu octal version as well. 
	

	
	
		
		

		
		
	


	




 To be honest, any design can be made more powerful, but I think it goes against the transportable design goal. If going speaker amp, I would think the SOHA 2 would be a better fit to make bigger as it's already bigger in terms of transistors and regulation as the CTH or a hybrid of the two on the input stage.


----------



## runeight

The very small footprint of this amp will be lost in a power amp. That's just the way it is.

 But, I've got too many things going right now to do this design. There is a stat amp in the works and boards getting ready to fab and the CTH kits to be offered for the next round.


----------



## mypasswordis

That's true. I'll definitely try to give your electrostatic amp a go once the kinks have been ironed out since it seems almost all of my headphones are now electrostats, with very few orthos and a K340 that still needs a recable. I'm glad you designed this particular hybrid with size/transportability in mind first, of course, and I still may build one at some point. I bought 20 12AU7 variants and I don't feel like they should just be sitting around doing nothing.


----------



## runeight

With all those 12au7s it would seem like you have to build one of these.


----------



## olblueyez

That is why I want to build one.


----------



## sachu

Oh dear..I screwed up my top plate..first time I was drilling such a big hole in aluminium and I messed it up pretty bad. I was using a hole saw and it all went awry.
 I used a wood boring bit to make the center hole after the mess with the hole saw.

 This is what happened.






 If anyone has a spare tube ring (from the tube ring protectors) please PM me. I could definitely use it to cover up my stupid mistake. *Never mind already placed order for a set on ebay*


 I tried driling the main hole with a hole saw and failed completely. Instead I plan to drill ou tthe hole using some other drill bit and put a tube ring around it to cover up the mess.

 The CTH stands for the amp and of course CA stands for Cavalli Audio. Ghetto I know..but the best I could do with a hand drill.


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_If anyone has a spare tube ring (from the tube ring protectors) *like in this picture* please PM me._

 

I posted a good amount of info where you posted this elsewhere.

 BTW Consider swapping out the pic in your post of my CTH lid since that top-mount heatsink test proved it was unnecessary & I'll be using a std internal one for the LV reg. CTHs do not need tacky spoilers


----------



## Forte

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Oh dear..I screwed up my top plate..first time I was drilling such a big hole in aluminium and I messed it up pretty bad. I was using a hole saw and it all went awry._

 

Ouch, Feel your pain, done that before. Won't use a holesaw anymore, do my tube holes with a hand file.

 If you don't have any luck with getting a tube ring I used one of these bushings from Mouser(561-MP15018). Might be easier for you to get, OD is approx 1.6", may be enough to cover it up. Also gives about 3/16" clearance around tube to help with cooling.


----------



## sachu

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Ouch, Feel your pain, done that before. Won't use a holesaw anymore, do my tube holes with a hand file.

 If you don't have any luck with getting a tube ring I used one of these bushings from Mouser(561-MP15018). Might be easier for you to get, OD is approx 1.6", may be enough to cover it up. Also gives about 3/16" clearance around tube to help with cooling.




_

 

Thanks for that...that's going to be bookmarked now.cheap and looks very good too..pity I already ordered the rings from ebay. Oh well another time..

 Took more measurements..looks like if I manage to not screw up further with the center hole, the tube ring should just about cover the mess up..Also deburring the holes around CTH and CA madea difference to the look..It looks better in person than in the photo


----------



## Netdewt

Is this amp available in any form right now?

 How is the performance on Grados?

 What do you guys think the skill level is? I have never built electronic components, but I know how to solder and I build other things.


----------



## wiatrob

Quote:


  Originally Posted by *Netdewt* /img/forum/go_quote.gif 
_How is the performance on Grados?

 What do you guys think the skill level is? I have never built electronic components, but I know how to solder and I build other things._

 


 Performance with Grados is excellent - I have been using my CTH proto with Grados at work for a while. It' s been my experience that Grados love hybrids, and this amp drives them quite well.

 Skill level is intermediate I'd say. All the soldering is straight forward, but there are a great many parts very close together. If you've not soldered board-level components, it would be good to practice both soldering and desoldering before tackling this amp.


----------



## dBel84

Got to hear the CTH at the PDX meet today 

  Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_ Compact Hybrid - much bigger than its diminutive size would suggest. I didn't have much time with them as in many meet conditions but the overall quick impression was very favourable - strong bass, good transient response, sparkly highs .... what more could a fella want. 




_

 


 Excellent amp ..dB


----------



## sachu

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_Got to hear the CTH at the PDX meet today 
 Excellent amp ..dB_

 



 Thanks for the pic dB...I was listening to it with the not properly modded headphones all this while. the SFIs and the HP2 sound great with it. Did you happen to take more pics of the CTH?


----------



## TimJo

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_Got to hear the CTH at the PDX meet today 

 Excellent amp ..dB_

 

Must be Sachu's? It is a great amp - listening now to The Fugees with the RCA 6189, and it sounds pretty efing good...

 Edit: Looks like it was Sachu's


----------



## sachu

Quote:


  Originally Posted by *TimJo* /img/forum/go_quote.gif 
_Must be Sachu's? It is a great amp - listening now to The Fugees with the RCA 6189, and it sounds pretty efing good..._

 

yep..that's mine..
 God..I have a huge shopping list of tubes I need to buy to roll on this little guy..Got a Slyvania 12AU7A doing duty..


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_God..I have a huge shopping list of tubes I need to buy to roll on this little guy..Got a Slyvania 12AU7A doing duty.._

 

I've said it before but really liking Amperex 6dj8s circa early 1960s... It could be my listening tastes or that I've few tubes costing > $10. Have a 6922 PQ white on the way & that'll be it for me for a while (always saying that tho


----------



## TimJo

Trying out a new tube this morning - a CBS 7318. Listening to a UK pressing of Leon Russel's first album and it is sounding extremely good. Soundstage is super precise and the old school reverb in the recording is represented with a very authentic sound. Clapton's guitar sounds great as well. 
	

	
	
		
		

		
		
	


	




 Haven't spent enough time with it yet, but it may turn out being my favorite so far (paired with my DT880's).

 Here's a very dark picture (it's snowing this morning)...


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Performance with Grados is excellent - I have been using my CTH proto with Grados at work for a while. It' s been my experience that Grados love hybrids, and this amp drives them quite well.

 Skill level is intermediate I'd say. All the soldering is straight forward, but there are a great many parts very close together. If you've not soldered board-level components, it would be good to practice both soldering and desoldering before tackling this amp._

 

I agree - your Compact Hybrid was excellent with my RS-1 at the last meet. I didn't get to do a detailed comparison between the Millett SSH and EF1 but it was certainly not below their level, based on memory.


----------



## keyid

Im using GE 5314A triple meca and it sounds really lovely driving k501. Does extremely well with classical and vocals, plus now k501 has well defined bass. Im using kiwame 47ohm on R18 and a stepped pot.


----------



## sachu

This is just wrong...I just switched out a Sylvania 12Au7a with a 12BH7A Gold Aero..My God the difference in sound..SO much more livelier..Was looking at the prices for some of the more sought after tubes for this amp on ebay..made me gulp. Glad that it doesn't need more than one tube. Else no way could I afford a few bugle boys and other more sought after tubes..I really have fallen into a rabbit hole with this amp ..my first every tube amp..

 keyid, the stepped pot you are using is the one from Taiwan I presume..how does it compare to the ALPS RK27...also I understnad a few of you chaps have used the vitaminq and the russian 0.22uF caps ..how big ar they..will they fit in the larger of the target cases?


----------



## nsx_23

So when is this amp finalized? 

 Reading all these juicy impressions makes me really, really want to whip out the soldering iron and build one for myself.


----------



## keyid

yes, i got the stepped "dact" like pot from overseas Taiwan, 100k. I cannot compare to the alps as I used a regular stereo log pot. The difference from the stereo log pot was significant. The sound became more cleaner and clearer. Its an incredible bargain imo, and ordered another for future builds. Took about a month to get to me. 

 I tried couple caps, wima, russian pio, and a polyester cap. I have little trouble with vitamin q's and sonicaps at the moment but im not even trying to get them to work. The caps are pretty big and are on legs standing above the board. Putting them under the board would work well as some builders have done and fit in the default case. 

 IMO the default yellow cap sounds the best so far. PIO and sonicap (when working) made the sound darker and murky, the amp seems to excels with fast transparent sound with the added smoothness of the tube. Though I didnt give them enough time to burn in, I figured it would not be as transparent as the default cap. This opinion however, was made solid once I switched cdp transport. I been using a denon dvd player feed to zapped zhoulo and with the default cap I did not like the highs. I got a sony dvp s7000 and that made a really big difference. The highs have little bit of sparkle with no glare. The sound became almost effortless and what I can describe as silky smooth. Kinda reminded me of presonus amp/dac smoothness. The amp seems to like better sources. I also think the kiwame has made the impact on the highs or it could be from using a lower ohm rating then the default, anyways get them from mouser cheap its worth experimenting. Jumping the r18's made the bass and mids shine but the highs became compressed. Was unable to distinguish the transient noise after the initial cymbal splash. 

 Yea tubes are addicting! I have some 12au7's from my soha and rolled the following:
 GE 6680
 Amprex 7316
 Tele smooth plates
 Brimmar 13D5 
 Siemens E82CC 
 Mullard 4003 
 RCA 5814 gray plates
 GE 5314a triple mica
 EH 12au7
 and still havent rolled my other half. I gave up trying to say which tube I like best as im still messing with the amp.


----------



## sachu

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_So when is this amp finalized? 

 Reading all these juicy impressions makes me really, really want to whip out the soldering iron and build one for myself._

 

It is getting there..I am guessing a week at most... A bunch of us prototype builders (including myself) are already on the list when the first production boards hit..I understand that kits are being readied for this amp that should make building this little doozy of an amp a breeze. 

 I can't wait to build my second one..the 12BH7A is a must for this amp.


 more pics


----------



## nsx_23

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I understand that kits are being readied for this amp that should make building this little doozy of an amp a breeze._

 

That was exactly what I wanted to hear. 

 How much is the total cost of building one of these beauties?


----------



## sachu

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_That was exactly what I wanted to hear. 

 How much is the total cost of building one of these beauties?_

 

I can't really comment on that as I do not know honestly. The folks who are working out the details of the kits will reveal all soon enough in at most a week I think).
 What I can tell you is that as a prototype builder, it probably cost me about 140$ USD not including tubes. This is for the stock version with only the opamps being changed to Burr Browns. The total also includes the tube rings that are going to arrive by the end of next week...

 I am honestly blown away by how good this sounds..I have it playing Diana Krall through my HP-2 yamaha orthos..brilliant. I will post final pics after I install the tube rings.


----------



## nux

Can anyone confirm whether 12AT7 tubes will work with this? I have been buying up some 12au7, 12bh7a and 12at7 tubes in preparation for building this amp!


----------



## cfcubed

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Can anyone confirm whether 12AT7 tubes will work with this? I have been buying up some 12au7, 12bh7a and 12at7 tubes in preparation for building this amp!_

 

They will work but probably have too much gain *Edit: I was wrong about it working but right about too much gain.* It's looking like its best to stay < 35mu. I link to runeight's tube compat post from the 2nd post in this thread. There may be a couple number transposes in the thread (8416/8614, 7316/7318 ?) and there may be others added to the list. A nice website consolidating info will be available soon. As well as a way to build this amp
	

	
	
		
		

		
		
	


	




 With differing levels of bundling options likely.

 Edit: WRT keyid's coupling cap experiences - Think preference hits here & everyone was/is happy w/BoM caps, but being tweakers its hard to resist tampering, uh, "improving"
	

	
	
		
		

		
		
	


	




. A couple of us are using non-Bom couplers (Sonicap Gen II, etc.) to good effect, so keyid's experiences may not be others (& vice versa).


----------



## wiatrob

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Can anyone confirm whether 12AT7 tubes will work with this? I have been buying up some 12au7, 12bh7a and 12at7 tubes in preparation for building this amp!_

 


 I have not been able to get 12AT7s to work satisfactorily. You will, however, enjoy the rest of your collection.


----------



## TimJo

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I understnad a few of you chaps have used the vitaminq and the russian 0.22uF caps ..how big ar they..will they fit in the larger of the target cases?_

 

I used VitQ's on my build, but it was with the caps on the underside of the board. I'm not sure there is room if you use the standard configuration.


----------



## runeight

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Can anyone confirm whether 12AT7 tubes will work with this? I have been buying up some 12au7, 12bh7a and 12at7 tubes in preparation for building this amp!_

 


 Tubes like 12at7 and 12ax7 will probably not work. Their operating points are just outside of what the tube servo can do. This is because neither of them is happy at 80V. However, as several have noted, their gain is too high anyway and your volume pot would become useless.

 Try some 6N1Ps. They'll be more fun.

 Gents, one reason for the choice of 12au7 as the design center tube is because, if all else fails, there are several sources of current production 12au7s. Thus, you won't have the problem of NOS stock getting depleted making the amp into a paperweight. 
	

	
	
		
		

		
			





 Additionally, 6N1Ps, 6922s, and 12BH7s are also in current production. Just remember me when you're rolling tubes.


----------



## TimJo

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Just remember me when you're rolling tubes. 
	

	
	
		
		

		
		
	


	


_

 

No worries there. Rolling tubes is becoming my new addiction.


----------



## keyid

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_
 Edit: WRT keyid's coupling cap experiences - Think preference hits here & everyone was/is happy w/BoM caps, but being tweakers its hard to resist tampering, uh, "improving"
	

	
	
		
		

		
		
	


	




. A couple of us are using non-Bom couplers (Sonicap Gen II, etc.) to good effect, so keyid's experiences may not be others (& vice versa)._

 

yes it was an opinion


----------



## runeight

OK folks, the moment you've been waiting for. 
	

	
	
		
		

		
		
	


	




 Boards and kits for the CTH are now available from:

Spruce Canyon Labs

 Bill Wiatroski (wiatrob) has agreed to supply the Rev 1 Boards and Kits. Please contact Bill through his website. And you will see lots of options to choose from.

 Also, please take advantage of the Cavalli Audio website for design and build information. The CTH section includes lots of important information gathered from the prototype process. If you pay attention to what is here you're amp will probably come up the first time you turn it on.

Cavalli Audio CTH

 And if you guys think I should create another announcement thread I'll do that too.

 wiatrob will probably follow this post with additional information.

 Thanks for everyone's interest.


----------



## forsakenrider

Right-on!


----------



## sachu

Alright!! I think this warrants an announcement thread...


----------



## wiatrob

First off - thanks to Alex and Chris for a great design. Mine has replaced my hulking M^3 as my work amp. Also the proto team for testing the waters.

 Rev 1 boards have been ordered. I am awaiting confirmation from the fabricating facility on an exact delivery time, but it should be within two weeks.

 Initial parts orders are on the way - I should have kit and option pictures up by the weekend. If you have general amp and technical questions, this is the place for 'em. If you have questions about the kit, please follow the link in my sig.


----------



## runeight

Announcement made here:

CTH Announcement Thread

 Prototypers, tell them how your amps are doing.


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Announcement made here:

 Prototypers, tell them how your amps are doing. 
	

	
	
		
		

		
		
	


	


_

 


 Indeed! As soon as I get a release amp built I am going to send it out on loan to the usual suspects.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Indeed! As soon as I get a release amp built I am going to send it out on loan to the usual suspects._

 

I suspect I might be a suspect?


----------



## nsx_23

Hurray! Kits!

 Just have a bit of confusion reading the website though. So if I opt for the complete kit with a black case, does it already come with the pre-drilled top or do I need to pay the extra $6 for that??

 I wonder if I should order the 12BH7A whilst I'm at it......fingers crossed shipping doesn't become ridiculously expensive.

 Damn, so much stuff I want to buy at the moment


----------



## sachu

The 12BH7A is a fantastic tube on this amp..I actually have a Gold Aero doing duty right now

 I think Wiatrob offers a 12BH7A with the kits


----------



## nsx_23

Yes he does, and I'm wondering if should go for it at $12USD....

 Argh. I want to buy an Audio GD compass, but also desperately want a tube amp (specifically, this one to build).......


----------



## sachu

man..this amp rocks so much that I can't wait to get my hands on the second board...looks like 4 are already spoken for..I am hoping I was included in that count..


----------



## cfcubed

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Yes he does, and I'm wondering if should go for it at $12USD...._

 

I've a Sylvania 12BH7A that cost me $10USD to get to my door.. You know its hard to get _any_ tube to your door for $12 w/shipping. BUT there are a lot to choose from for this amp in particular. Make sure you give 6dj8s a listen too
	

	
	
		
		

		
			






*sachu: this amp rocks so much that I can't wait to get my hands on the second board *
 Agree... That's why I quickly snagged up one of the protos that became available. Think its best though when those not involved in the design say such things, as has every prototyper I think.

 Going with a huge 6" x 4.2" x 2.2" case for this 2nd build. A DAC may find its way in there someday


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_man..this amp rocks so much that I can't wait to get my hands on the second board...looks like 4 are already spoken for..I am hoping I was included in that count.._

 


 You weren't 
	

	
	
		
		

		
		
	


	




 But are now...


----------



## MrSlim

One of the final prototypes:


----------



## cfcubed

Looks nice MrSlim! All you need now is a black sharpie
	

	
	
		
		

		
		
	


	




 I used my son's little Tester's black paint on a SOHA build way back.....Or maybe not, the silver holes do pull in the nice chrome tube ring.

 Just wanted to say the amp is great in its target case too, a breeze to tote around as TimJo's mentioned in his impressions here. 





 I just loved the sound & features enough to give the 2nd one a bigger home to include more goodies


----------



## MrSlim

Thanks CF, I put a bit of countersink on the holes to make them stand out a bit more, and look a little more "finished" . Mine is for work duty and it fits perfectly on top of a little FM tuner I have on my desk so the ultimate minimum size wasn't so critical. I may do a small one as an amp for my Digital keyboard though, since I have the RK97 pot and probably 1/3 of the parts for it.


----------



## fordgtlover

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_One of the final prototypes:_

 

Is that the recommended Hammond 1455K1202BK case?


----------



## dracoV

WooHoo! 
	

	
	
		
		

		
		
	


	



 Glad to know that it reaches production stage. "The long await" is nearly end.

 Timing is just about right. I'll have a long vacation next month.
 I'll have enough free time to source parts, and if the board can arrive
 in time I might be able to finish it before my business trip to Japan 
	

	
	
		
		

		
		
	


	




 Kudos for you guys' hard work, runeight cfcubed and proto team.


 For those who are interested in the CTH, highly recommend, 
 read through the info. on CTH on Cavalli Audio web site.
 It is quite educating and informative.

 Cheers,


----------



## olblueyez

Ok, dumb question for you guys. Why do the prototypes have the inputs up front?


----------



## wiatrob

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Ok, dumb question for you guys. Why do the prototypes have the inputs up front? 
	

	
	
		
		

		
		
	


	


_

 

Chris and Alex will have to chime in - but I think the design goal was to use this mostly as an amp for portable sources - hence the front I/O. Now that we know how well this amp performs, I can see more people wanting to use RCA ins...

 There's also not much room for rear jacks in the target 1455K1202 case, Could be done with clever routing and no fuse/power switch.

 The 1455K1602 has a bit more room, as seen in some of the other builds...


----------



## wiatrob

My Mr. Slim, what a large knob you have!


----------



## holland

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Ok, dumb question for you guys. Why do the prototypes have the inputs up front? 
	

	
	
		
		

		
		
	


	


_

 

Mine is on the rear side. From the left, first switch is the power, fuse, heater voltage, input. I didn't want to use RCA on the rear as I wanted to have more room between the power section and the input. Shielded cable runs up the input side to the front.


----------



## olblueyez

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Mine is on the rear side. From the left, first switch is the power, fuse, heater voltage, input. I didn't want to use RCA on the rear as I wanted to have more room between the power section and the input. Shielded cable runs up the input side to the front.






_

 


 That is what I was thinkin, use a mini, OR, a larger chassis with a dac.


----------



## MrSlim

FordGTLover: No, thats a 1455K1601BK, with the aluminum end panels, which means I had to go with isolated panel jacks on all the connectors. I'm partial to the aluminum look vs the "crinkle finish" plastic end panels. Ultimately the plastic end panels are simpler to deal with though. I decided to go with the 1601 because I wanted to put in a 1/4 Jack, RCA's and an RK27. 

 Olblueyez: a couple of the protos had input jacks at the back, but also used a bigger/different case to do it in. The spec'd case (and the 160X case) have enough room for a power switch or fuse, and the heater switch, so there's no room for any kind of input jack. I have an inline fuse on the output of my transformer just in case, which saved my bacon when I did a major faux paux, during building. Also, since all the power supplies are at the back (there are 3 of them, including some high frequency stuff..) you would need well shielded cables to route over the board. In keeping with the compact nature of the amp, it becomes a tradeoff: Looks vs functionality, and for me it wasn't a big issue to have the inputs at the front. The proto boards did not have any holes for standoffs, so you are limited to how you could mount the board. The production boards do have them, so they could be mounted in bigger cases, although the "Compact" part if this beauty is part of its cache I think. 

 Wiatrob, I don't know whether to Blush 
	

	
	
		
		

		
		
	


	




 or say Thanks for the compliment


----------



## olblueyez

I like it because its simple and small and it uses the 12AU7. I have a case full of AU7's not being used, I even have a Tung-sol 12BH7, that thing is a bear, whopper base and nice clean highs. Just make sure its Tungsol though, Tungsol put out some rebranded BH7's. Met someone here who was pissed at the results he was getting and when we compared pictures he had an RCA rebranded to Tungsol. The RCA is nice but its super thick and smooth and rolled off and slow. Tungsol has the bass weight of the RCA but its brighter up top and quicker.


----------



## MrSlim

Olblueyez, I'm using a used RCA(or so said the vendor) 12BH7A and I have to say that it sounds very fast and unrolled off in the CTH. It's the first tube I tried, so I haven't got a reference point though. It could be a function of the amp though.. A few other prototypers are using the 12BH7 also and like it also, althought not sure of the manufacturer. Wanna loan me that 12BH7 Tung Sol to try out?


----------



## wiatrob

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_I like it because its simple and small and it uses the 12AU7. I have a case full of AU7's not being used, SNIP_

 

You owe yourself a crack at this amp if you love tube rolling (and I can tell you do 
	

	
	
		
		

		
			





) and especially the 12BH7...


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I suspect I might be a suspect? 
	

	
	
		
		

		
		
	


	


_

 

You are the next on the review list, it's making it's way south to you!


----------



## MrSlim

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Tubes like 12at7 and 12ax7 will probably not work. Their operating points are just outside of what the tube servo can do. This is because neither of them is happy at 80V._

 

I can confirm that the 12ax7 will NOT work, having attempted to use it as my first test tube, causing much frustration on my and Runeight's part..


----------



## MrSlim

Keyid : Do you have any internal pics of your build? Id love to see what it looks like with the stepped attenuator. Did you use a Hammond Case?


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_You are the next on the review list, it's making it's way south to you!_

 

I'll make Bluto, Sherwood and Naamanf get to hear it too!


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I'll make Bluto, Sherwood and Naamanf get to hear it too!_

 

Sherwood is actually hoarding it now


----------



## MrSlim

Hey, has anyone tried a 6N1P in it yet? There are tons of Russian ones on Ebay and cheap too.


----------



## keyid

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Keyid : Do you have any internal pics of your build? Id love to see what it looks like with the stepped attenuator. Did you use a Hammond Case?_

 

Havent made much progress on the casing... I hope to find some time in the next coming weeks. I got a hammond case but its the longer version and all the components does seem to fit nicely.


----------



## sachu

Does anyone have a 6N1P to spare...Or how do you guys feel about making a group buy for some 6N1Ps from ebay..10 tubes is about 22 shipped...plus additional shipping (probably 3 $ each)..

 I wouldn't mind doing handling the group buy if 4 more join in. That way each of us gets a pair of the tubes..total should work out to about 7$ for the pair of tubes shipped to your door..if more are interested, then we can order about 20 tubes..

 Pm me if anyone wants to take this forward.


----------



## scompton

I'd be up for it even though I'm not going to build this amp soon.


----------



## sachu

Quote:


  Originally Posted by *scompton* /img/forum/go_quote.gif 
_I'd be up for it even though I'm not going to build this amp soon._

 

There is the 6N1P-EV version which is supposed to be superior for 17$ + 12 $ shipped for 10 tubes *(5 pairs)*. If you guys want to go for that then the price for a pair may end up being about 9$.

*Source of the tubes* to maintain full disclosure

 Please note that I am quoting shipping to lower US only... Shipping to Canada is not a problem for me but might cost a little bit more (First class International from USPS)

 Got a quote of 45$ for 20 6N1P-Ev tubes shipped to me..So that makes it out to be 10 pairs: Including shipping to lower 48 states, a pair of these tubes should come out to our target of $4.5 + First class mail USPS shipping to your zipcode from mine (97219).

 If you want more than one pair let me know. group buy is now *closed*.
 Depending on how many members we have signed up by then I will go ahead with either of the group buy options :

 1> 5 pairs of tubes. I might even get the seller to sell me the exact number of pairs if more than 5 but less than 10 pairs have been spoken for.
 2> Order the 10 pairs is we have at least 8 - 9 pairs spoken for.

 A running count of members interested in this:
 member (no of pairs) (Country)
 1> Sachu (1) (USA)
 2> Scompton (1) (USA)
 3> MrSlim (1) (Canada)
 4> zkool448 (1) (Canada)
 5> nux (2) (Australia)
 6> keyid (1) (USA)
 7> TimJo (1) (USA)
 8> rds (1) (Canada)
 9> jacc1234 (1) (USA)

 _______________________
 Total no of pairs = 10
 _______________________
*
 Disclaimer:* Tubes being tubes..there might be a few in the lot that may not work, microphonics or noise...please be aware of this. hence the reason for going in for pairs, redundancy. I will test each one in my own amp to make sure at least one working tube makes it to each member in the worst case scenario where half the tubes are non-functional


----------



## cfcubed

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Ok, dumb question for you guys. Why do the prototypes have the inputs up front? 
	

	
	
		
		

		
		
	


	


_

 

Think wiatrob covered this pretty well... The 1st 2 posts in this thread talk about the goals for the project - A prime one being small form factor. Then over time, much design work (sims, PCB layout, etc) and prototyping, it was found desktop class performance (superior, according to impressions here) could be delivered in the target case. If every inch was put to good use.
 With the PS components in the rear of the PCB, builds in the target case would need to be creative to fit rear RCAs...

  Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_I hope this ends up in kit form, if it does then I want 3._

 

You may build your three any way you wish
	

	
	
		
		

		
		
	


	




 I'll have front (mini) & rear (RCA) inputs on this 2nd build as well as mini + full size front output jacks, RK27, etc. BTW, it is saying something that most those w/protos are looking to build another. 

 Looks like we may be seeing a lot of CTH builds around here in the next month or so and we'll get to see lots of ideas WRT casing & integration.


----------



## scompton

sachu, I'll go for either, so whatever the group decides.


----------



## keyid

ill try one or pair (however it comes) 6N1P-EV, heater uses 6.3v?


----------



## nux

Just wondering if one of these 220uH inductors might be a good Mouser available one:
RLB9012-221KL
18R224C

 First one datasheet shows max current as 1Amp (not 1mA as shown on the mouser page..) Lead spacing looks about right compared to the BoM Digikey one. Second one is slightly wider but has a lower DC resistance.


----------



## sachu

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Just wondering if one of these 220uH inductors might be a good Mouser available one:
RLB9012-221KL
18R224C

 First one datasheet shows max current as 1Amp (not 1mA as shown on the mouser page..) Lead spacing looks about right compared to the BoM Digikey one. Second one is slightly wider but has a lower DC resistance._

 


 Second one looks like it would work...first one has too high DCR from the one mentioned in the BOM


----------



## cfcubed

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Just wondering if one of these 220uH inductors might be a good Mouser available one:
RLB9012-221KL
18R224C_

 

sachu is on target... If you look closely at this (click through 2X), my 2nd cth, think you see the 2nd coil you listed:





 It's working fine for me BUT it was a heck of jam, leads didn't line well, 1N5820 was tricky to fit next to it, toroid is better/preferred, etc, etc. I only used it because it was on hand, I had the LM2595 & I could sufficiently test (scope) that it works. If one took the chance on using such a coil, they'd want to sub 1N5818 for 1N5820 to ease the fit.

 You need to source the LM2595 anyway & that source might have the proper toroid 220uH 0.8A or higher (I linked to an Aussie source back in this thread).

 Note: Clearly any complications from deviations from the published BoM (or parts incl w/kits) fall on the builders hands
	

	
	
		
		

		
			





 Be very sure of what you are doing.


----------



## sachu

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_ill try one or pair (however it comes) 6N1P-EV, heater uses 6.3v?_

 

Yes, the heater is 6.3Volts



 I am trying to swing for a few 6N23P tubes along with the 6N1P..
 That way 10 of each tube type would mean we all get one 6N1P-EV and one 6N23P tube (but the chances that one or both of the fail to work becomes greater). 
 This way we all get to try out and roll more tubes on this wonderful amp

 Not trying to complicate anything..for now the original group buy continues.


----------



## nux

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_sachu is on target... If you look closely at this (click through 2X), my 2nd cth, think you see the 2nd coil you listed:

 Note: Clearly any complications from deviations from the published BoM (or parts incl w/kits) fall on the builders hands
	

	
	
		
		

		
		
	


	




 Be very sure of what you are doing._

 

Ah excellent! I might buy both and see how the smaller one goes. It should fit easier but will generate a bit more heat. I will report back when I get some PCB's and parts!
 And I already have a few LM2595's so don't need to source them, hence trying to get everything from Mouser.


----------



## sachu

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Ah excellent! I might buy both and see how the smaller one goes. It should fit easier but will generate a bit more heat. I will report back when I get some PCB's and parts!
 And I already have a few LM2595's so don't need to source them, hence trying to get everything from Mouser._

 

yeah, i think I will give it a try too...I have almost a half dozen of the LM2595s...am all set..now need to decide whether to order one board or two..


----------



## cfcubed

I think its funny you guys have LM2595s just laying around... I thought it was a bit of an obscure part.

 WRT heater parts - The values, ratings & other characteristics (DCR, Q, impedance) are very important to its functioning properly, as noted in its parts list. SMPSs are picky in their parts & not a good place to go subbing. BTW feedback resistor values are very important too. Really look spec sheets over & the most support you may get is a "Good luck"


----------



## sachu

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I think its funny you guys have LM2595s just laying around... I thought it was a bit of an obscure part.

 WRT heater parts - The values, ratings & other characteristics (DCR, Q, impedance) are very important to its functioning properly, as noted in its parts list. SMPSs are picky in their parts & not a good place to go subbing. BTW feedback resistor values are very important too. Really look spec sheets over & the most support you may get is a "Good luck"
	

	
	
		
		

		
		
	


	


_

 

hahah...what's DIY without smoking a few capacitors , busting a few diodes and transistors to set you off tugging at the board removing the damamged parts, ordering extra supplies...yeah..lots of fun.


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Yes, the heater is 6.3Volts
 I am trying to swing for a few 6N23P tubes along with the 6N1P..
 That way 10 of each tube type would mean we all get one 6N1P-EV and one 6N23P tube (but the chances that one or both of the fail to work becomes greater). 
 ._

 


 Fooo - I have 6N1ps, and I can't rememeber if I tried them in the CTH - I'm pretty sure I did, and they worked. 

 I got a little carried away swapping tubes when i fired the amp up, then I got stuck on the 12BH7


----------



## forsakenrider

Ive been listening to russian 6n1p's for the last 2 days. They sound decent, nice and flat. But i must admit, I like the colouration of a tube, thats what makes it a tube amp to me!


----------



## Netdewt

What's the markup on the kit vs. buying parts separate?


----------



## Forte

Yep, 6N1P-EV works well in the CTH and sounds great. Not in the same league as the 12BH7 or the better 6DJ8's, but I prefer it to most of the 12AU7 tubes I have tried so far. Also some tubes seem to match better with certain headphones than others, so with all the tubes that can be rolled in and all the headphones most people here have there is endless fun to be had with this Amp.

 IIRC the EV suffix means heavy duty, longer life & military spec although different guides give different definitions and there are conflicting opinions as to which sound better. Have ordered some regular 6N1P's to see how they compare. Just be aware that shipping from Russia or Eastern European countrys can be very very slow.


----------



## keyid

Quote:


  Originally Posted by *Netdewt* /img/forum/go_quote.gif 
_What's the markup on the kit vs. buying parts separate?_

 

My build came to $200+ this is without tubes or the board cost and couple other minor items. Couple things that mouser and digikey doesnt have is the power adapter (plug n play) and tube socket good luck finding them in one place. But I did order some good stuff. 

 This figure has risen because of upgrades couple more tubes, caps, and resistors.


----------



## cfcubed

Quote:


  Originally Posted by *Netdewt* /img/forum/go_quote.gif 
_What's the markup on the kit vs. buying parts separate?_

 

TimJo may have answered this best here... I'd be surprised if wiatrob made minimum wage working for you in making these kits & assoc cornucopia of options available. 
 Hope he ends up making at least enough for a Happy Meal per kit
	

	
	
		
		

		
		
	


	




 Oh & you can always download the BoM from the official CTH site & spend time pricing things out to your door...


----------



## nux

I've just about finished putting together a Mouser order (over US$400 currently!) and just have a few final questions for the prototypers.

 Which 1/4" jacks are recommended from Mouser? And if using them, is the larger case the best option?

 And are there any other recommended tweaks or different components that I should get to try out? Different caps/knobs etc? Really want to make sure I get everything I need in one go.

 Cheers.


----------



## runeight

nux, I changed the BoM recently because there was an error. The correct version now is 2015a. The only significant change is R13 which should be 1k5 (not the 1k8 that was in the previous BoM). We also increased R18 to 100R instead of 56R because the prototype group seems to like this value a little better. But this is builder choice.


----------



## cfcubed

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Which 1/4" jacks are recommended from Mouser? And if using them, is the larger case the best option?_

 

What runeight said WRT BoM. I have doubts about fitting a "nice" 1/4" jack in the std case, but perhaps if its mounted higher than the hole guide.... If you are gunning for RCAs + 1/4" jack + maybe minis you are most likely out of the target case & might as well do a bigger pot. Just my opinion.

 BTW, if doing metal end plates probably best that no jacks, etc ground to case & we know OG must float/be insulated on outputs... Only that single SG ground wire should electrically connect to case. If so consider this 1/4 jack as its insulated & can switch out another output and maybe these insulated minis.


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_... We also increased R18 to 100R instead of 56R because the prototype group seems to like this value a little better. But this is builder choice._

 

There's room to squeeze sip sockets in for R18, that's what I did, then you're free to tune the resistance to your needs/phones...


----------



## TimJo

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Which 1/4" jacks are recommended from Mouser? And if using them, is the larger case the best option?

 And are there any other recommended tweaks or different components that I should get to try out? Different caps/knobs etc? Really want to make sure I get everything I need in one go.

 Cheers._

 

I used the Neutrik locking type for the first time, and I'm not sure how I feel about it. It works fine - it's just big. I have also used their M Series, and those work fine. As far as room goes, I'd go with a longer case if you can. Here's a picture or two from my build to give you an idea.


----------



## keyid

Get couple resistors for R18
 I would recommend KOA SPR2 and SPR5 carbon film resistors, they say its same as Kiwame's. I like 47ohms.

 Get some wima caps MKP & others, along with the recommended cap. Verify they fit on the board. 

 Get sockets, with small and large input/hole sizes some caps have larger diameter legs, also Kiwame's might have larger diameter then the rest of the resistors. 

 I like the original bom for R15 - 33.2k & R14 - 1M. Though its not recommended. It takes longer for e12 to trip, but I think I like the sound that way or it can be my imagination; hard to tell sometimes. 



  Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_I've just about finished putting together a Mouser order (over US$400 currently!) and just have a few final questions for the prototypers.

 Which 1/4" jacks are recommended from Mouser? And if using them, is the larger case the best option?

 And are there any other recommended tweaks or different components that I should get to try out? Different caps/knobs etc? Really want to make sure I get everything I need in one go.

 Cheers._


----------



## wiatrob

Quote:


  Originally Posted by *TimJo* /img/forum/go_quote.gif 
_I used the Neutrik locking type for the first time, and I'm not sure how I feel about it._

 

I know how I feel about 'em - *poop*! I _love _the looks though. I remove the locking spring - still very positive contact, and great aesthetics...


----------



## sachu

we have almost 10 pairs spoken for in the group buy for the 6N1P-EV here...

 I will keep this open for one more day and then close it.please PM me if you want to get in on this.

Group buy here

 I have added a disclaimer....please read..These Russian dealers are known to be pretty good with the stock of tubes that they carry..but you never know.


----------



## Halvor

How does the CTH compare to the millet max, and does it drive hd650 well?


----------



## holland

can't comment on the mille max. It drives the HD650 quite well. A few of the proto builders own the headphones. It drives my 600 ohm Sextett just fine, as well. It drives my harder to drive K271S headphones fine as well.


----------



## Forte

Quote:


  Originally Posted by *Halvor* /img/forum/go_quote.gif 
_How does the CTH compare to the millet max, and does it drive hd650 well?_

 

A much wider selection of tubes to roll and no adjustments to make when tube rolling other than a simple on/off heater switch was what convinced me to build one of the proto CTH amps. 

 Drives my HD600 very well, same with MS-1 and DT770.


----------



## Halvor

How is the difference in SQ?


----------



## wiatrob

Drives my 650's with authority. Grado Rs-1s and Orthos as well... Denon D-5000's too...


----------



## TimJo

It drives my DT880's and AKG 701's with no problems - power to burn...

 I own several Max's and love them. In terms of comparisons, all I can say is they are very different. The Max is more of a stationary desktop amp in my book, whereas the CTH is incredibly portable. The Max uses the 12 volt car radio tubes, whereas the CTH uses a whole slew of high voltage tubes, with no adjustments for biasing - kind of a plug and play design - which is very nice. With the Max, there are multiple configurations that can be built simply by choosing different combination's of transistors and caps, whereas the CTH changes sound signatures by rolling tubes. After a few solid weeks of listening to my CTH, I'm beginning to think that using BOM components is all that is needed - upgrading caps will probably have a less significant effect than upgrading tubes. At this point, if I were to build another one, I'd probably just use WIMA's as coupling caps, and invest the savings into more tubes.


----------



## MrSlim

I'm with you on the Cap issue TimJo. I bought some WIMA's when I had to do another order with Mouser, and and it sounds very nice. Whether there is any difference between them and the BOM caps is debatable. I socketed the C4's so I can try the Sonicaps that I got from CFcubed in the mini group buy, but not sure I want to mess with it now.. Maybe when i build a second one, and can do some side by side A/B comparisons. I just got a 6DJ8, since CF was raving about them..


----------



## MrSlim

Just looking at the posts so far, the CTH seems to be able to drive all the usual suspects very well: HD600 and 650, DT770 and 880, RS-1, MS-1, K271S, Sextett, K601 and K701 and D-5000's


----------



## sachu

Quote:


  Originally Posted by *Halvor* /img/forum/go_quote.gif 
_How does the CTH compare to the millet max, and does it drive hd650 well?_

 

Hmmm...the Millet Max is so so when compared to other hybrids..but I would love to do a head to head with the Max Millet..The last time I heard one, *I* thought it was dull sounding. There are much better hybrid designs out there.

 Hey but you listen to what ever gets you going..

 Regarding whether it would drive the HD650..no problems there..The CTH drivers all my headphones which are orthos wonderfully...I have tried my 32 ohm SFI pickering, 50 ohm Fostex T50Rps, and 150 ohms Yamaha HP2 and YH-100s..and as you know orthos need a lot of juice to sing in a matter of speaking...


----------



## keyid

drives k501 very well too


----------



## zkool448

Firtst of all, the project looks very impressive and I already see some great looking proto builds 
	

	
	
		
		

		
			





 I hear the first round of CHT kits are starting to roll in and I'm also eagerly anticipating delivery of my SOHA II kit from glassjar. By the looks of it they just might get built at the same time 
	

	
	
		
		

		
		
	


	




 Advice needed: I've only built a cmoy and 2 starving students. Let's just say I have both SOHA II and CTH kits on hand, which project would you recommend I tackle first and why?

 Also, the CTH populated board appears quite 'tight'. In terms of socketing, which components (if any) would most recommended remain socketed vs. permanently soldered on the board, (as well as test points during initial setup or during troubleshooting)? thanks.

 zk


----------



## sachu

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_Firtst of all, the project looks very impressive and I already see some great looking proto builds 
	

	
	
		
		

		
		
	


	




 I hear the first round of CHT kits are starting to roll in and I'm also eagerly anticipating delivery of my SOHA II kit from glassjar. By the looks of it they just might get built at the same time 
	

	
	
		
		

		
		
	


	




 Advice needed: I've only built a cmoy and 2 starving students. Let's just say I have both SOHA II and CTH kits on hand, which project would you recommend I tackle first and why?

 Also, the CTH populated board appears quite 'tight'. In terms of socketing, which components (if any) would most recommended remain socketed vs. permanently soldered on the board, (as well as test points during initial setup or during troubleshooting)? thanks.

 zk_

 


 Definitely the CTH I would think..Just so long as you make sure you populate everything correctly, the amp should work on turn on. While the board is tight, stuffing the board of all the 175 components should be about a days' job at most..

 One piece of advice I can give you is, if you see yourself getting fidgety or frustrated while soldering, lay your soldering iron down and take a break..you are likely to mess things up a lot more if you are all pissed off.

 The ones I had socket were, R14/R15 and R13...I know some folk have installed SIPS for the coupling capacitors so they can try out different ones..if that is your thing then installing SIPS there may be a good idea.


 I will let runeright chime in on which components that may be a good idea to socket.


----------



## scompton

Can you give a link to the SIPS you use?


----------



## sachu

Quote:


  Originally Posted by *scompton* /img/forum/go_quote.gif 
_Can you give a link to the SIPS you use?_

 

Here you go SIP sockets


----------



## keyid

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Here you go SIP sockets_

 

Larger caps / resistors require bigger sized holes then the 310-13-120-41-001000. I got these SIPS and had to "sharpen" the legs of some parts to get them to fit. Though the holes on the board accepts them fine, so no worry's for onboard soldering.


----------



## wiatrob

Zcool - I'd actually recommend building the SOHA II first. It's a larger scale build with all the components sections of the CTH (HV/LV PS, tube input, discrete buffer, e12) with an intermediate parts count and more room to maneuver. Follow the schematic for the build and you'll have a very good idea of how the CTH will go together. In 1/3rd the board real estate!

 HOWEVER, judging form your SS case work, you seem to have a level of attention to detail that would serve well whether you built either first or both simultaneously.


----------



## wiatrob

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_Larger caps / resistors require bigger sized holes then the 310-13-120-41-001000. I got these SIPS and had to "sharpen" the legs of some parts to get them to fit._

 

These are also the SIPS I use. Resistors (RN55s) were no problem for me to socket...

 I don't know if socketing caps is recommended... But I'm sure some will try it!


----------



## MrSlim

I socketed the C4 (coupling) caps, and it seems to be working fine with WIMA's, although there have been "issues" with some of the high end Caps.. I haven't tried the Sonicaps I ordered for it..


----------



## DKJones96

Looks like I have another project after my PPA and Bijou!


----------



## sachu

Final pics of my prototype CTH build..

 Isn't it puurty























 The CA is my way of paying tribute to the design house that created the amp..Cavalli Audio.

 CTH in Star Wars font for the amp..serving dual purpose..

 Nice convection air currents between the two sets of holes to cool her down so she doesn't burn herself from her hot sexy self.


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Final pics of my prototype CTH build..
 Isn't it puurty_

 

Yes it is... Much better than your previous pics of it
	

	
	
		
		

		
		
	


	



 Have to say that's one big momma of a knob on that little pot... Bet you didn't have any RK27s around...


----------



## sachu

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Yes it is... Much better than your previous pics of it
	

	
	
		
		

		
		
	


	



 Have to say that's one big momma of a knob on that little pot... Bet you didn't have any RK27s around..._

 






..yeah much better now..
 True, I would have used an RK27 if I had one..Will put in a stepped attenuator in the next one..or an RK27 depending on the budget...but the knob is sooo shiny..me like it a lot..


----------



## MrSlim

OK I want to see someone stuff a stepped attenuator in a 1455K1601 box..


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_





..yeah much better now.._

 


 You know what they say: The difference between an amateur and a professional? A professional knows how to cover their mistakes!


----------



## sachu

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_OK I want to see someone stuff a stepped attenuator in a 1455K1601 box..
	

	
	
		
		

		
			



_

 

I thought one you chaps had used that DACt style attenuator from taiwan..was plannning on getting that for my second CTh actually.


----------



## MrSlim

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I thought one you chaps had used that DACt style attenuator from taiwan..was plannning on getting that for my second CTh actually._

 

Keyid did, but he hasn't cased his up yet...


----------



## zkool448

Thanks for the advise Sachu, wiatrob. 

 I'm currently reading through pages and pages of info on both Alex's site and builder's thread (very detailed I must add). Things may or may not go smoothly but as long as I follow the directions carefully I think I'll be fine -- guess I'll find out soon enough what challenges lay ahead for both these projects. Thanks!

 zk


----------



## keyid

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Keyid did, but he hasn't cased his up yet..._

 

yea, hope to get this sucker cased up soon. The "dact" style stepper is pretty close to the size of an alps, maybe little fatter; it should fit nicely in the longer case. Im so relieved that the sonicaps is working, thought something was wrong with my build. Now I can play with more caps without worry.


----------



## olblueyez

Hey everyone, Here is a great deal on some nice tubes, some of you guys could split this up! Tube on the left with the convex anodes looks like my tungsol and was probably made by tungsol (tons of bass weight and clean clear highs). Not sure about the Motorola but it may be an old 50's RCA (Thick and sweet). Westing house looks like it could be a Tungsol, The GE's I'm not sure about (maybe they are GE 
	

	
	
		
		

		
		
	


	




 or Tungsol). The last 3 RCA's are newer and could possibly be from Mexico or Canada, but at 80 balloon's for 10 tubes I would take my chances, hell, ya never know, maybe the non-US tubes sound good too. 
http://cgi.ebay.com/10-NOS-RCA-GE-Other-Some-D-12BH7-Audio-Tubes_W0QQitemZ400037767287QQihZ027QQcategoryZ6462 9QQssPageNameZWDVWQQrdZ1QQcmdZViewItem"]http://cgi.ebay.com/10-NOS-RCA-GE-Ot...QQcmdZViewItem[/URL]






 Nice looking RCA's, for me this tube was as smooth as it gets, too smooth in fact for my amp but with your SS output section it may be the ticket. (VERY TUBEY SOUNDING).
http://cgi.ebay.com/QUAD-RCA-12BH7A-...QQcmdZViewItem

 Dont know a thing about it but for 15 bucks I may just buy it myself.
http://cgi.ebay.com/NOS-NIB-RAYTHEON...QQcmdZViewItem

 Bad Ass Mofo*'S*, nice tube for a set of cans light on bass weight and rolled off at the top.
http://cgi.ebay.com/12BH7A-12BH7-RAR...QQcmdZViewItem
http://cgi.ebay.com/NOS-Tung-Sol-12B...2em118Q2el1247

 Interesting English Tube, Bo dont know diddly, may be the biggest pork chop you ever ate or your bulldozer?!?!?
http://cgi.ebay.com/BRIMAR-12BH7-VAL...dZp1638Q2em122


----------



## cfcubed

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_< snip> I just got a 6DJ8, since CF was raving about them.._

 

And what do you think of it? I notice the deals I pointed to are no more (Amperex 6DJ8 circa very early 60's white label Holland - $12 shipped?). I'm still loving the 2 of these I have, for rock variants at least... Even maybe better than the 6922 PQ I snagged for < $20. Maybe I'll bring a load of tubes to NYC & try to crawl through them & see what I think...

 A CTH tube thread should probably happen pretty soon.


----------



## sachu

Group buy is now closed..we have 10 pairs spoken for..I have made the payment for the tubes..


----------



## MrSlim

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_And what do you think of it? I notice the deals I pointed to are no more (Amperex 6DJ8 circa very early 60's white label Holland - $12 shipped?). I'm still loving the 2 of these I have, for rock variants at least... Even maybe better than the 6922 PQ I snagged for < $20. Maybe I'll bring a load of tubes to NYC & try to crawl through them & see what I think...

 A CTH tube thread should probably happen pretty soon._

 

i haven't had a lot of time to listen to it so far, but I do like it. I guess I haven't done a lot of "critical" listening for a long time, maybe I need to get my ears attuned to the nuances. I have noticed that there is lots of detail with them.. I listen more to classical, and jazz, as well as a lot of CBC Radio 2 at work. On Thursday night I listened to all 4 of the Oscar Peterson "Exclusively for my Friends", and they sounded very good. I started with a 12BH7a though, which a few others really like as well, and I thought was very dynamic. I was one of the one's who snagged that deal you mentioned..


----------



## nux

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_One of the final prototypes:_

 

What knob did you use MrSlim? Looking for a black one similar to this to match a black case, on the RK097 pot. I'm happy to modify the pot with heatshrink to get it to fit.

 Is the black tube surround around the hole in the kit photos this bushing?

 And thanks for all the tips, I'm building a few for myself and some friends so just wanting to make sure I get everything all in one go!

 Cheers!


----------



## ppchiu

Can anyone tell me what kind of sound quality I should expect from this amp? What other amps are it this league? Another amp I was considering was one of the Ibasso ones since they're nice and small. Is this one comparable?


----------



## HeadphoneAddict

Quote:


  Originally Posted by *ppchiu* /img/forum/go_quote.gif 
_Can anyone tell me what kind of sound quality I should expect from this amp? What other amps are it this league? Another amp I was considering was one of the Ibasso ones since they're nice and small. Is this one comparable?_

 

It reminded me a lot of other tube hybrids like a Millett and Head-direct EF1. It has a nice rich powerful sound with Grados, and it takes the edge off the Grados nicely as well. The iBasso D10 is the only iBasso that can come close to this tube hybrid in sound quality, but it's not even close in power or refinement and the synergy with Grados is much better with the Cavalli Compact Tube Hybrid. The Cavalli amp could also drive very inefficient orthodynamic headphones that portable amps just can't drive hardly at all. I neglected to try it with my HD600, sorry - but I expect it to do very well there too.


----------



## Forte

Thought it was about time I posted a few pics of my CTH/Bantam build. 

 Originally planned to use the extra room in the 1455K1601BK case for a nice pot, 1/4" jack and RCA's but soon realised that a small DAC could be fitted in the extra space instead. All board parts are standard BoM except for Nichicon electrolytic and Wima film caps. 

 The only problem encountered was a reversed D4P diode which caused two transistors(Q3P & Q1P) to fail, but very easy to fix. Would recommend anyone building this amp build in stages double checking everything as they go since there are a lot of parts on a small board, also check carefully for solder bridges. Still a few changes/tweaks to come, Power switch going on the rear, sonicaps for C4L/R and need to change output resistors(socketed to make this easy) as the gain is still a little high for lowZ headphones.

 The overall sound is very detailed, fast with plenty of bass and drives all headphones I have tried with ease. The bass doesn't dominate but is there where it should be and is deep and powerfull. Nice clear sparkling highs, seems to do everything well.


----------



## sachu

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Thought it was about time I posted a few pics of my CTH/Bantam build. 

 Originally planned to use the extra room in the 1455K1601BK case for a nice pot, 1/4" jack and RCA's but soon realised that a small DAC could be fitted in the extra space instead. All board parts are standard BoM except for Nichicon electrolytic and Wima film caps. 

 The only problem encountered was a reversed D4P diode which caused two transistors(Q3P & Q1P) to fail, but very easy to fix. Would recommend anyone building this amp build in stages double checking everything as they go since there are a lot of parts on a small board, also check carefully for solder bridges. Still a few changes/tweaks to come, Power switch going on the rear, sonicaps for C4L/R and need to change output resistors(socketed to make this easy) as the gain is still a little high for lowZ headphones.

 The overall sound is very detailed, fast with plenty of bass and drives all headphones I have tried with ease. The bass doesn't dominate but is there where it should be and is deep and powerfull. Nice clear sparkling highs, seems to do everything well. 
	

	
	
		
		

		
		
	


	


_

 

That is one sweet looking amp Forte....well done!!!
 see you squeezed in a bantam in there..I have plans on doing that somewhere down the line.

 Curious as to how are you doing the switch from analog to digital input?


----------



## Forte

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Curious as to how are you doing the switch from analog to digital input?_

 

3PDT toggle switch on back panel. 


 
 Bantam output wired to the bottom row of switch, 3.5mm wired to the top row and the centre row to the amp. Just have to make sure the L, R and ground all connect to the correct positions so they switch correctly.


----------



## sachu

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_3PDT toggle switch on back panel. 


 
 Bantam output wired to the bottom row of switch, 3.5mm wired to the top row and the centre row to the amp. Just have to make sure the L, R and ground all connect to the correct positions so they switch correctly._

 

Neat...should definitely give this a try in my CTH...looks like you did not install the on/off seitch or left out the heater switch..or am I trippin; 
	

	
	
		
		

		
		
	


	




 Also, what is that black ring at the top left corner in the back


----------



## Forte

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Neat...should definitely give this a try in my CTH...looks like you did not install the on/off seitch or left out the heater switch..or am I trippin; 
	

	
	
		
		

		
			





 Also, what is that black ring at the top left corner in the back_

 


 The small rocker switch is the heater switch. 

 There will be a power switch when I get a replacement for the one I broke, the black ring is where the switch will go (just put in the bush to tidy up the hole for now)......


----------



## MrSlim

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_What knob did you use MrSlim? Looking for a black one similar to this to match a black case, on the RK097 pot. I'm happy to modify the pot with heatshrink to get it to fit.

 Cheers!_

 

Nux.. You are going to love the amp.. Just take your time and you won't blow anything up..

 These are the knobs I bought: 2,30x22 Aluminum Hi-Fi CD VOLUME TONE CONTROL KNOB,B - eBay (item 120382088037 end time Mar-23-09 20:32:53 PDT)


----------



## grendel23

[QUOTEThese are the knobs I bought: 2,30x22 Aluminum Hi-Fi CD VOLUME TONE CONTROL KNOB,B - eBay (item 120382088037 end time Mar-23-09 20:32:53 PDT)[/QUOTE]

 I used the same knobs on my SOHA II and SSMH, It is hard to see the index mark, so I filled it with white paint, worked very well.


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_There will be a power switch when I get a replacement for the one I broke,_

 

Forte - I really like your build... Appearance, neatness & integration. Two or three @ the NYC meet suggested that including a DAC in the box would make it an ideal desktop all-in-one. This requires a slightly bigger case like the one you used or like that of my 2nd CTH (pic w/lid off on NYC meet impressions thread - pic that wiatrob noted).

 Haven't delved into the DAC/USB/PC bit. I think my sources are now the weak point of my kit. Primarily use 256k/VBR MP3 off 5.5 Gen iPod & sometimes an old Sony D-777. Decent portable solutions but need something fancy @ home (esp after what I saw/heard yesterday
	

	
	
		
		

		
		
	


	




 BTW hope my little box makes it to you soon - I mailed them all out the same day.


----------



## Forte

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Forte - I really like your build... Appearance, neatness & integration. 

 Haven't delved into the DAC/USB/PC bit. I think my sources are now the weak point of my kit. Primarily use 256k/VBR MP3 off 5.5 Gen iPod & sometimes an old Sony D-777. Decent portable solutions but need something fancy @ home (esp after what I saw/heard yesterday
	

	
	
		
		

		
		
	


	




 BTW hope my little box makes it to you soon - I mailed them all out the same day._

 

Thanks.

 My first try at the DAC/USB/PC bit. Huge improvement over my iPod classic line out and as good as or even better than my X-Fi Soundcard which came as a surprise. 

 Hope to see your parcel tomorrow. Received some tubes Friday that shipped from the west coast same day.


----------



## ppchiu

I'm trying to decide which Cavalli project to take on and it seems like the SOHAII and the CTH is similar in difficulty, can anyone compare the two's sound quality?


----------



## Nebby

Just kinda doing some what-if thinking; but what considerations would be needed for using two boards for balanced use? Aside from a transformer/wall-wart capable of 2A


----------



## sachu

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_Just kinda doing some what-if thinking; but what considerations would be needed for using two boards for balanced use? Aside from a transformer/wall-wart capable of 2A_

 

DOn't think there is any....but will let more qualified people answer the question.


----------



## rds

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_...just put in the bush to tidy up the hole..._

 

Am I the only one immature enough to find that amusing?


----------



## sachu

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Am I the only one immature enough to find that amusing?_


----------



## wiatrob

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_Just kinda doing some what-if thinking; but what considerations would be needed for using two boards for balanced use? Aside from a transformer/wall-wart capable of 2A_

 

The idea has been floated around this thread, but no technical point shave been discussed AFAIK. 

 I happen to have some plans to do a balanced version of this amp myself, but I have a bit on my plate with The Poor Man's stat amp and this project


----------



## Nebby

I have a couple speakers to build, a subwoofer, a dac or two, a speaker amp, and then maybe a CTH. Doesn't stop me from contemplating it! (or from picking up the parts....)


----------



## olblueyez

I must be loosing my sight, I dont see the ordering links anymore.


----------



## sachu

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_I must be loosing my sight, I dont see the ordering links anymore._

 


 Its there..looks like it has been updated a bit.


----------



## olblueyez

I see bigger cases are available, that for people wanting rca's and the like?


----------



## sachu

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_I see bigger cases are available, that for people wanting rca's and the like?_

 

Yep, 

 RCAs full stereo jack, ALPS pot..Mine is a bigger case too with the RCAs...

 Shipped mine off to Smeggy for a listen/review


----------



## rds

Is it possible to squeeze an rk27 in the small case? I'm ok with mini jacks if necessary, but would like to have a high quality pot.


----------



## sachu

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Is it possible to squeeze an rk27 in the small case? I'm ok with mini jacks if necessary, but would like to have a high quality pot._

 

I think you could..but will have to probably mount it off center, bit higher on the front panel ..or mount it on the top plate...

 Chris (cfcubed) of Bill (wiatrob) can give you more insight on this as they have built it with the smaller case.


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Is it possible to squeeze an rk27 in the small case? I'm ok with mini jacks if necessary, but would like to have a high quality pot._

 

I don't think its possible.... I spent some time prior to populating the 1st CTH seeing if I could make it fit to no avail. Didn't consider top panel mounting tho. Still don't think you'd find the nearly 1" cube of space (would only fit over flat resistors/diodes I think).

 Although perhaps a compromise, I'm plenty happy w/the BoM pot that supports the major transportability of my 1st CTH.


----------



## wiatrob

It would be very challenging to shoehorn an rk-27 win the BoM case. Impossible? 
	

	
	
		
		

		
			





 There is exactly 25mm from the top of the PCB to the lip of the Hammond. That's the size of an Rk-27. Moving it over a notch, you can flush it up to the case top slot. 

 This buys you 3-4mm. You'd have to bottom mount the caps underneath it (nd I don't know if C1P will fit under the board) and maybe jam Q1L all the way down to the board, but you _might_ just make enough clearance. Might have to solder IC1 directly to the board (you've got some builds under your belt so you can weigh the risk) 

 A challenge, but maybe...


----------



## MrSlim

For all the effort in squeezing it in, you might as well use the 1600 case, and have lots of room for it.. It was easy for me..
 and what if you went to the effort and then it still didnt fit, or you shorted something out.. 
 Rememeber size does count..


----------



## TimJo

My build has the RK27 and RCA's as well, and I'd say go for the longer case. At 3"x6" it's still really compact. The extra length in the case means you will have better airflow for cooling the voltage regulator because you will be able to add some holes underneath the case, allowing for more efficient natural convection. All I have are some holes on the bottom, and one row along the top of the back plate of the amp.

 One note for anyone using a longer case though, it does mean the board is not locked in place by the case itself, and can slide back and forth, from front to back. I took care of this problem by adding a standoff between the bottom of the board and the bottom of the case. Adding a standoff also means that the board has extra stability when rolling tubes. There is a hole underneath the tube socket, and I added a 4-40 buttonhead screw there before soldering the socket, and then attached a 4-40 threaded standoff to the underside of the board. I've attached a photo for reference...


----------



## holland

There are lots of options.

 The standoff under the socket is a good one.

 A piece of cardboard in the slot to take up the slack works as well. That's what I did with my Context Engineering case, and that's also what I did with the Alien DAC a couple of years ago.

 With the bigger case and a big pot you should be able to shove the board into the pot and use the cardboard as a wedge. Another option is an angle bracket to brace one end of the board as well, and utilizing the cardboard to fill the space to the faceplate on the other end.


----------



## wiatrob

All,

 the 1.1 rev of the PCB which is on order has 4 standoff holes for securing the PCB. Alex has not posted the image yet. 

 -Bill


----------



## MrSlim

Timjo, I really liked your idea about putting a standoff under the tube socket, but you should have spoken up about it before I had already mounted my socket.. I'm blaming you.. 
	

	
	
		
		

		
		
	


	




 I put a couple of 3/4 inch bolts up through the bottom with a nylon bushing on them to use as board stops. You could even use one as the case Star ground point.


----------



## cfcubed

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Timjo, I really liked your idea about putting a standoff under the tube socket, but you should have spoken up about it before I had already mounted my socket.. I'm blaming you.. 
	

	
	
		
		

		
		
	


	


_

 

Yep. The minute I saw Timjo's socket riser bit I knew how I was mounting the socket on my 2nd CTH... Although I went w/o a standoff to case bottom because of my sacrificial little hammond brackets (pre-V1.1's standoff holes):









 There are pics of this 2nd CTH of mine in that 'bay mid case floating around here (earlier in thread, NYC meet impressions) & my PB acct. 

 > With the bigger case and a big pot you should be able to shove the board into the pot and use the cardboard as a wedge

 I used a stick on "case foot" from an assortment on the back of my 1/4" jack front-panel output jack as a PCB bumper in my 2nd CTH. _(Edit: It's possible that adhesive-backed case foot could fall off allowing the PCB to move, so better to use something more permanent)._


----------



## smeggy

=That's a cool idea.


----------



## sachu

well I didn't use any kind of board stop in mine..the boarseem to be quite a tight fit and i had to exert considerable pressure to get it to slot it.
 I didn't bother with any board stops as it was such a tight fit.

 Have carried it everywhere without one and no problems..even shipped it yesterday and I am confident it wouldn't have budged at all.


----------



## smeggy

I may have to put my CTH build plans on hold for a little while.


----------



## wiatrob

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I may have to put my CTH build plans on hold for a little while._

 

Oh no, you didn't lose another fingertip, did you?


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I may have to put my CTH build plans on hold for a little while._

 

What gives?..I thought you were already sold on the CTH even before I shipped it to you


----------



## smeggy

lol

 Not this time, I almost pushed the button last night but I may have to redirect funds... have to wait and see.

 I have to talk to a man about a dog. There are grumblings in the air and I have a few options, depends on what a few people say though. I'm in a small holding pattern until I get more into on my dastardly plans..


----------



## HeadphoneAddict

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_lol

 Not this time, I almost pushed the button last night but I may have to redirect funds... have to wait and see.

*I have to talk to a man about a dog.* There are grumblings in the air and I have a few options, depends on what a few people say though. I'm in a small holding pattern until I get more into on my dastardly plans.._

 

I always thought that meant you have to go to the bathroom?


----------



## smeggy

That's where all my best scheming happens


----------



## holland

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_That's where all my best scheming happens 
	

	
	
		
		

		
		
	


	


_


----------



## rds

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_A challenge, but maybe...
	

	
	
		
		

		
		
	


	


_

 


 Not physically impossible then? I like those odds.

 I do prefer the look of that small case. Plus it comes with a pre-drilled pref top 
	

	
	
		
		

		
		
	


	




 ...


----------



## smeggy

Looks like I'm back in the running here thanks to a good friend


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Looks like I'm back in the running here thanks to a good friend 
	

	
	
		
		

		
		
	


	


_

 

huh?..don't really follow you there?..you saying you gonna build one now?


----------



## smeggy

looks like it


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_looks like it 
	

	
	
		
		

		
		
	


	


_

 

Nice..i thought I wouldn't be building another, but just scored a case for the second one..


----------



## wiatrob

It's nice to see some impressions starting to show up, however brief:

http://www.head-fi.org/forums/f45/of...ml#post5552306.

 Holding it's own with some heavy hitters! Up next: CTH vs Menace?


----------



## TimJo

I have to say that I continue to be amazed at what this little amp can do. Like I have said before, it has become clear to me that the sound quality is heavily dependent on the combination of the tube and the headphones - but once you get a good match for the type of music you want to listen to, the sonics can be truly amazing.

 I've been going through a bunch of my favorite albums and it's like rediscovering them all over again. Some of things that I continue to notice are crystal clear details in the percussion, amazing reproduction of studio reverb, nice separation and placement of the individual instruments, very quiet vocal fills in background overdubs that I've never noticed before - the list goes on...

 Because of the level of detail that this amp can provide, the other observation I can relate is that it puts more pressure on the performance of the source. Good sources (including the mastering itself) can sound really good - bad ones sound so-so. My best source is my turntable, and I have the CTH connected directly to the phono preamp (see my sig) and when I put on a good recording (like the Cisco 30th aniv. reissue of _Aja_) it is as good as I've heard it before. I've also put on my 38 year old copy of _All Things Must Pass_, and it was almost like hearing it for the first time. To be honest, I'm not sure how much more detail can actually be extracted from my turntable, but I'm going to build a Bijou to find out.


----------



## smeggy

It's very nice, I'm listening to sachus CTH right now and I like!


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_It's very nice, I'm listening to sachus CTH right now and I like!_

 






 Remember it is supposed to come back to me..supposed to


----------



## smeggy

Yeah, whatever sachu...


 hehe


----------



## wiatrob

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Yeah, whatever sachu...


 hehe 
	

	
	
		
		

		
			



_

 

Looks like you _*won't*_ have to build one after all - Good thing Sachu is planning a second build!


----------



## smeggy

Yeah, saved me quite a bit of time too


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Looks like you *won't* have to build one after all - Good thing Sachu is planning a second build! 
	

	
	
		
		

		
		
	


	


_

 

hey hey Bill..stop giving ideas to Gary...


----------



## MrSlim

C'mon Smeggy, just write sachu a cheque and be done with it...


----------



## Sherwood

Hey gents.

 While I've hardly been keeping up with the development process of this little amp, Bill was kind enough to loan me his for two weeks in exchange for some beers and a few words, so I wrote a small review. If you're interested, I posted it in a separate thread here.


----------



## keyid

great review!

 Wanted to share some findings. I got some more KOA resistors and couple other parts due to little piece of wire shorting out the 24 reg. Everything works fine and tried some 100ohm and 150ohm for output on R18. These resistors sound different than what I heard from the vishay's. The soundstage got wider and has more image separation, however; it still have an intimate sound. With the vishay's, the higher ohm I went the the sound become dull and lifeless. With the KOA resistors it sounds more coherent, little more relaxed, but not dull, and the notes are more defined especially towards the end (decay?). Right now im settled at 100ohm for the senn and 150ohm for k501. Also got some wima mk2 and they sound great! (had mk10 before and had to rig it with longer leads) I cant resist not turning it up.


----------



## wiatrob

KeyId - thanks for the tip on the KOAs. 

 I can also confirm that the amp works with 6Bq7s. Hopefully someone watching this thread (Ole Blue Eyes?) will have some info on the 'sweet' varieties of this tube.


----------



## Forte

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_ With the vishay's, the higher ohm I went the the sound become dull and lifeless. With the KOA resistors it sounds more coherent, little more relaxed, but not dull, and the notes are more defined especially towards the end (decay?). Right now im settled at 100ohm for the senn and 150ohm for k501._

 

That confirms what I heard with the VD output resistors, went straight back to the default value. How are you changing between 100ohm and 150ohm? I have a few here in different values but the leads are much thicker than with the VD's and don't fit the sockets?



  Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I can also confirm that the amp works with 6Bq7s. Hopefully someone watching this thread (Ole Blue Eyes?) will have some info on the 'sweet' varieties of this tube. 
	

	
	
		
		

		
		
	


	


_

 

So how do they sound?


----------



## keyid

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_That confirms what I heard with the VD output resistors, went straight back to the default value. How are you changing between 100ohm and 150ohm? I have a few here in different values but the leads are much thicker than with the VD's and don't fit the sockets?_

 

quick and dirty method of cutting lead at an angle so that its really sharp, also have some high grit files if I cant cut it thin enough.


----------



## wiatrob

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_So how do they sound?_

 

The one out of the three I like the best is very warm, with the slightest (but not unpleasant) bloat on bass. The buffers tighten it up. 

 These are nos/used from the 'bin' at my local electronics store (JB Saunders in Boulder rules!) So not pedigreed, but definitely worth trying...

 There's another shop in town that carries tubes and I'm going to see if they have any.


----------



## wiatrob

Well, probably won't have too much time for tube rolling in the immediate future. 
	

	
	
		
		

		
		
	


	


*CTH 1.1 PCBs have arrived.* I am completing a proof build to make sure everything is working on the boards.

 Tiny Pic:


----------



## Nebby

Sweet, mounting holes! I like!


----------



## smeggy

will this board need a new BOM?


----------



## runeight

Yes. Just a few BoM mods. The new board information and BoM are on the Cavalli Audio Website.


----------



## smeggy

Thanks


----------



## wiatrob

Quick picture of the proof build for the 1.1 PCB - it works great!


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Quick picture of the proof build for the 1.1 PCB - it works great!_

 

woohoo..excellent Bill.that looks so darn good..I suppose my PCB will be in the mail tomorrow..


----------



## rds

Very niiiiice!


----------



## olblueyez

I was hung up on the lack of RCA's but that is just way to nice to let something like that stop me.


----------



## Sherwood

That mesh top plate will sure come in handy.


----------



## olblueyez

Quote:


  Originally Posted by *Sherwood* /img/forum/go_quote.gif 
_That mesh top plate will sure come in handy._

 

I know this will be a dumb question but why?


----------



## Sherwood

well, the proto I got from Bill put out a lot of heat. It's either mesh top, or drill 200 holes. The latter is not an enticing idea, by any means.


----------



## olblueyez

Told you it was a dumb question.


----------



## malldian

Would it be foolish to take this on as a first time DIY?


----------



## sachu

Quote:


  Originally Posted by *malldian* /img/forum/go_quote.gif 
_Would it be foolish to take this on as a first time DIY?_

 

Personally I don't think it would be too much of a daunting task. Iknow many people will say make a CMOY and all that stuff.

 So long as you are diligent about placing the components correctly and have a steady hand..it could be done.

 The possibilities of solder bridges are high and would be my only concern for an inexperienced person tackling this project and that's why it would help to have a steady hand.

 Taking your time during the build is extremely important.


----------



## malldian

My hand isn't that steady. Maybe I will try some other ones first..


----------



## smeggy

Heh, well this will be my second build, next is the EHHA tube hybrid and then finishing up a Beta22 with most of the hard work already done. So I may be jumping ahead of myself but what the heck. they'll either work or they wont


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Heh, well this will be my second build, next is the EHHA tube hybrid and then finishing up a Beta22 with most of the hard work already done. So I may be jumping ahead of myself but what the heck. they'll either work or they wont 
	

	
	
		
		

		
		
	


	


_

 

Guys, its a simple build honestly..just stuffing the board..only that the components are packed real tight..take your time with it and you can do it.

 Else you can always commission me to build one for you for a small fee


----------



## smeggy

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Guys, its a simple build honestly..just stuffing the board..only that the components are packed real tight..take your time with it and you can do it.

 Else you can always commission me to build one for you for a small fee 
	

	
	
		
		

		
		
	


	


_

 

Now where's the fun in that


----------



## nsx_23

Sachu, How much tighter then, say, a mini3?


----------



## smeggy

look at the tightest area of a mini3 and them multiply that over a board twice the size. It's a lot of parts and very tightly packed.


----------



## sachu

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Sachu, How much tighter then, say, a mini3?_

 

about the same..just that there are a whole lot more components..like 170+ of them..which means the chances of things going wrong are greater if one is not concentrating


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_about the same..just that there are a whole lot more components..like 170+ of them..which means the chances of things going wrong are greater if one is not concentrating_

 


 Now, given, this was my second build of this amp, but I just laid everything out, labeled, stuffed, and double checked my work against a big print of the silkscreen. *Paid attention to ALL of Alex' guideline on the website*, and it worked when I fired it up.

 But you are right _concentration is key_!


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_look at the tightest area of a mini3 and them multiply that over a board twice the size. It's a lot of parts and very tightly packed._

 

Yes but no SMD. SMD (somehow) tripped me up before, to the point of ordering replacement even tho I _thought_ I was somewhat skilled
	

	
	
		
		

		
			




 All through-hole & as sweet a PCB layout/design/silkscreen as I can imagine in a 3"x5" space. 
 Think 160-piece jigsaw puzzle w/all pieces numbers and PLENTY of support text & images on CTH site to assure you get em in right spot
	

	
	
		
		

		
		
	


	




 But do need reasonably stead hand & PCB vise a great help. Billing this as an "intermediate level" project even tho there is no device matching or pots to adjust, etc.


----------



## TimJo

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Now, given, this was my second build of this amp, but I just laid everything out, labeled, stuffed, and double checked my work against a big print of the silkscreen. *Paid attention to ALL of Alex' guideline on the website*, and it worked when I fired it up.

 But you are right concentration is key!_

 

 Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Personally I don't think it would be too much of a daunting task.

 So long as you are diligent about placing the components correctly and have a steady hand..it could be done.

 The possibilities of solder bridges are high and would be my only concern for an inexperienced person tackling this project and that's why it would help to have a steady hand.

 Taking your time during the build is extremely important._

 

I'll chime in here as well and say this isn't a very difficult build as long as you follow the advice above. 

 The difficulty one may run into is if you need to replace components due to errors when stuffing the board. If you are super careful, and don't rush the build in order to get it done right away, then it's an easy project.

 I verified all my components against the parts list and schematic as I went, and then marked each on off with a hi-lighter after looking for solder bridges after soldering. _*Slow and Methodical*_ is the way to go with this build.

 Pay attention to part orientation - like the tombstoned diodes. There's a good diagram on Alex's site - just make sure the diode body sits on the silk screened circle, and it's a no brainer...

 Just lots of components - tightly packed.... Here are some photos from early in the build of my prototype to give you an idea...


----------



## smeggy

Listening to sachus CTH with my K1000 right now. At moderate to loud levels it's doing a damn nice job. Goes quite nicely with them and doesn't appear to be struggling in any way with the load. It's too loud for comfort at max volume


----------



## HeadphoneAddict

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Listening to sachus CTH with my K1000 right now. At moderate to loud levels it's doing a damn nice job. Goes quite nicely with them and doesn't appear to be struggling in any way with the load. It's too loud for comfort at max volume 
	

	
	
		
		

		
		
	


	


_

 

I have a 4-pin to SE adapter so when wiatrob's CTH gets here to try out I will have to give the K1000 a try. They work fine off my Single Power Square Wave XL balanced, and also can get too loud to listen with it.


----------



## wiatrob

Larry, as soon as the proof build get's burned in I will send it along. Probably by the weekend...


----------



## MrSlim

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Listening to sachus CTH with my K1000 right now. At moderate to loud levels it's doing a damn nice job. Goes quite nicely with them and doesn't appear to be struggling in any way with the load. It's too loud for comfort at max volume 
	

	
	
		
		

		
		
	


	


_

 

Wow, has anyone found a headphone the CTH won't do a nice job with? 
 It's amazing it's capable of driving K1000's to a reasonable level..


----------



## sachu

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Wow, has anyone found a headphone the CTH won't do a nice job with? 
 It's amazing it's capable of driving K1000's to a reasonable level.._

 

I think if we change the output resistor on mine..it will drive the K1000 more easily so you wouldn't have to turn it up that high...


----------



## smeggy

for the same decent volume level, my T50RP is at 10, the K1000 is at 2 oclock. Not bad when the control goes round to 5:30!


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Larry, as soon as the proof build get's burned in I will send it along. Probably by the weekend..._

 

No hurry...


----------



## nsx_23

How would the CTH go with a pair of Pro 900?


----------



## cfcubed

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_How would the CTH go with a pair of Pro 900?_

 

Build one & let us know.


----------



## Henmyr

I've deciding between building this and CKKIII. Have anyone of you built both and if so any comments on the sound of both?

 I'm leaning towards the CKKIII as I like the convenience of SS. What speaks for the CTH is the smaller size, and that it only use one tube, which minimizes the hassle. In the end though, it's the sound that matters. The amp will be used with all of my headphones.


----------



## sachu

I recently sold the CK2III as the CTH was above and beyond the better headphone amp.
 The CK2III has a solid bottom end but the CTH blows it away in all other areas..


----------



## smeggy

Ok, just to keep you all apprised of it's performance with nasty cans..

 I'm running one of the worlds hardest to drive phones on the CTH right now and it's doing a very nice job with them. The K1k is a known difficult load, the original Wharfedale isodynamic is like a K1k with a boat anchor attached. It's at 5oclock for decent levels... the knob only goes to 5:30. 

 Yeah, that kind of load!!
 Impressive.


----------



## sachu

wow..you aare able to run the wharfedale isos with the CTH..nice..and the knob *only *goes to 5.30 eh?


----------



## smeggy

Mmm, quick question here... does the CTH have a thermal trip of any kind and it cut itself out for a little while and then popped itself back on again with a low ping sound. I thnk the woofeys may be more than the CTH is really comfortable with


----------



## TimJo

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Mmm, quick question here... does the CTH have a thermal trip of any kind and it cut itself out for a little while and then popped itself back on again with a low ping sound. I thnk the woofeys may be more than the CTH is really comfortable with_

 

Sounds like the e12 tripped. Were you just listening, or were you adjusting the volume when it happened?


----------



## runeight

Good job exercising this little amp. 
	

	
	
		
		

		
		
	


	




 It does not have any thermal protection, but it does have the e12 offset protection circuit. If you are running very high currents through the O/P devices and the phase splitter it may occasionally generate a transient offset that exceeds the detection limit. This should not happen for normal conditions and should be pretty rare even with what you are doing.


----------



## smeggy

Just listening and it suddenly cut out and came back a minute or so later. It's done it about 3 times now, only with these phones at max power. First two times I thought it was bad connections, apparently I found the CH limit


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Mmm, quick question here... does the CTH have a thermal trip of any kind and it cut itself out for a little while and then popped itself back on again with a low ping sound. I thnk the woofeys may be more than the CTH is really comfortable with_

 

Right, it was an e12 trip. Things like line voltage flux may cause this too once in a while.

 Even if he wasn't twirling the volume at the time, I'd suggest there may be a couple/few component adjustments we might want to make a CTH routinely driving "very difficult" loads. Removal/shorting of R18s (output resistors), e12 resistor tweaks from CTH tweak thread come to mind. Perhaps more, but if someone ends up habitually using a CTH this way we'd see. (E.g. If the difficult load phones don't sound as full/rich/fat as non-difficult cans - coupling caps, if TO92s get too hot little paddle HSs, etc.)

*Edit* WRT _apparently I found the CH limit_ - Don't count the little tiger out yet for this sort of thing


----------



## smeggy

Cool, I'm gonna be making one soon hopefully so any thoughts of modifications to it you can suggest can be incorporated in the build and it can then act as a testbed for feedback.

 Back to more reasonable loads it seems happy again.


----------



## wiatrob

Yup, as with many DIY projects, the design goals were addressed to the 'majority' of headphones in use (whatever they are 
	

	
	
		
		

		
		
	


	




) 

 As CFCubed pointed out - there's room in the design to accommodate different operating conditions...


----------



## holland

Check the source for DC. DC coming in gets amplified. The volume knob attenuates all AC and DC, but with a difficult load the knob gets set higher. Try a quick test with an interconnect that has coupling caps, if you have bits on hand to make one.

 Edit: When music plays DC will go up and down for direct coupled sources.

 you can also try pulling the headphone from the jack and just max out the knob.


----------



## smeggy

heh, I have no idea what any of that means. I'm more of a 'paint by numbers' DIYer 
	

	
	
		
		

		
		
	


	




 I have the electronics knowledge of a gnat, besides, this isn't my amp so I won't be messing with this one


----------



## holland

Remove the headphones, max out the volume, and see if the relay trips (the click and the red light). Leave it for a bit and see if it flashes green and red (or some repeated clicking). Lower the volume knob and see if you can find the point where it doesn't. Make sure your track is on repeat. Different music will behave differently.

 Source DC offset (from music) + amp gain can easily trip the e12. With a cap on the input of the amp, it shouldn't trip from source (that's the interconnect with the caps inline). From there, you can tell if it's the headphone load that's causing issues.

 Just saying, because my source trips up other amps with the e12, and it goes away if I cap couple. I know my source is DC coupled (no output caps).


----------



## smeggy

Ah, gotcha. I like good explanations like that. Very helpful thanks. I'll try that tomorrow.


----------



## Henmyr

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I recently sold the CK2III as the CTH was above and beyond the better headphone amp.
 The CK2III has a solid bottom end but the CTH blows it away in all other areas.._

 

Thanks for the answer.

 Do the CHT better the "large, deep 3D-like soundstage" that I've read that the CK2III has? What headphones did you test both with? Did you try both with your very hard to drive orthos? I would guess that the outcome COULD (as I really have no idea) be different as my current headphones are not that hard to drive in comparison.

 thanks again.


----------



## sachu

Quote:


  Originally Posted by *Henmyr* /img/forum/go_quote.gif 
_Thanks for the answer.

 Do the CHT better the "large, deep 3D-like soundstage" that I've read that the CK2III has? What headphones did you test both with? Did you try both with your very hard to drive orthos? I would guess that the outcome COULD (as I really have no idea) be different as my current headphones are not that hard to drive in comparison.

 thanks again._

 

The only reason I actually built the CK2III in the first place was due to the fantastic synergy it had with my HD580 and DT770s..But once I discovered the orthos the CK2III wasn't all that much fun. 

 The CTH and the CK2III were both tested with all my orthos and the AKG K701s. The CTH was better with all. The CTH also had the better soundstage by a large margin, excellent highs, detailed and very nice mids compared to the CK2III.

 I see that you have the Grado RS1..apparently the CTH is supposed to be heavenly with the RS1.

 I reiterate, the CTH is a much better amp than the CK2III.


----------



## keyid

I agree with the CTH assessment though I didnt have them at the same time and im biased towards tubes. I also rolled various CK2III output transistors and I preferred tubes.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_The only reason I actually built the CK2III in the first place was due to the fantastic synergy it had with my HD580 and DT770s..But once I discovered the orthos the CK2III wasn't all that much fun. 

 The CTH and the CK2III were both tested with all my orthos and the AKG K701s. The CTH was better with all. The CTH also had the better soundstage by a large margin, excellent highs, detailed and very nice mids compared to the CK2III.

 I see that you have the Grado RS1..apparently the CTH is supposed to be heavenly with the RS1.

 I reiterate, the CTH is a much better amp than the CK2III._

 

The RS-1 was very good with the CTH - better than the orthos (sorry wiatrob), and I should get a chance to try the CTH again in a couple of weeks (if I didn't offend wiatrob just now).


----------



## keyid

not getting much luck dampening the ortho (yh-1) to mate with the CTH. Must have tried 20 different combinations of felt thick/thin, cotton webbing, blue tack and micro fiber. They are very hard to drive once dampened, my vol is around 3-4'o clock w/ 100ohm on R18 output resistors. Hope to hear RS-1 with CTH, maybe the push I need to finally get one.


----------



## Giuss

Is it possible to see complete schematics?


----------



## holland

.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_SNIP (if I didn't offend wiatrob just now)._

 

No offense, I bought a pair of RS-1s because of it


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_No offense, I bought a pair of RS-1s because of it 
	

	
	
		
		

		
		
	


	


_

 

And I'm sorry about your wallet!


----------



## holland

Quote:


 CTH<snip>...<snip>CK2III 
 

I just want to be practical. They are different. 
	

	
	
		
		

		
		
	


	




 I have both as well, and will continue owning them (I can't sell my builds). The CK2III is in my stable of "go to" amps for work. It always comes back in rotation. The CK2III is cheaper, in the long run. You don't have all these tube itches @ $xx per tube. The CK2III is a very steady and solid performer. It is a very good amp, clean crisp edges, good extension, and very hard to beat for the money. Output transistor changes are relatively small in impact, compared to the wide array of tubes. Tube amps, I find somewhat lacking around the edges. You have to swap and invest in tubes to get what you're looking for (IMO). It's also much easier to control gain on the CK2III.

 The performance of the CTH depends drastically (as do all hybrids) on the tubes utilized.

 If you want to swap both tubes and transistors, the SOHA II is your guy (for more money).

 It all comes down to preferences and what you need. The CTH, while nice, is primarily targeted at transportable. The CK2III is not entirely in that vein.


----------



## sachu

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I just want to be practical. They are different. 
	

	
	
		
		

		
		
	


	




 I have both as well, and will continue owning them (I can't sell my builds). The CK2III is in my stable of "go to" amps for work. It always comes back in rotation. The CK2III is cheaper, in the long run. You don't have all these tube itches @ $xx per tube. The CK2III is a very steady and solid performer. It is a very good amp, clean crisp edges, good extension, and very hard to beat for the money. Output transistor changes are relatively small in impact, compared to the wide array of tubes. Tube amps, I find somewhat lacking around the edges. You have to swap and invest in tubes to get what you're looking for (IMO). It's also much easier to control gain on the CK2III.

 The performance of the CTH depends drastically (as do all hybrids) on the tubes utilized.

 If you want to swap both tubes and transistors, the SOHA II is your guy (for more money).

 It all comes down to preferences and what you need. The CTH, while nice, is primarily targeted at transportable. The CK2III is not entirely in that vein._

 

I will not agree with you on that..but we are both entitled to our own opinions. I only put down what I found when I compared the two amps.

 The CK2III I had was extremely rolled off in the highs and a mid range that was hardly as involving as the CTH was. it did have a better lowend.
 I must have spent about 170$ on my CTh including over a dozen different tubes. I agree with the more esoteric tubes you will eventually end up spending a lot more than the actual amp cost to build.


----------



## holland

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I will not agree with you on that..but we are both entitled to our own opinions._

 

sure are.

  Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_The CK2III I had was extremely rolled off in the highs and a mid range that was hardly as involving as the CTH was. it did have a better lowend._

 

Sounds like something was wrong, to be honest. The sound of the CTH drastically changes with tubes swaps. There were some tubes that were really not that great in the CTH, so blanket statements don't really mean a whole lot without taking that into consideration.


----------



## sachu

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_sure are.

 Sounds like something was wrong, to be honest. The sound of the CTH drastically changes with tubes swaps. There were some tubes that were really not that great in the CTH, so blanket statements don't really mean a whole lot without taking that into consideration._

 

Look..I don't want to get into a back and forth thing here..

 I just reported what I heard and my opinion. 

 I tried the best tubes I had with the CTH but the bass wasn't up to the mark when compared to the CK2III. Changing to boutique parts or some fancy tubes may do the trick..

 I did forget to mention that the bass improved ont he CTh with an RCA 5963 but lost some of the sparkle in the highs that the 12BH7 had.

 The CTH did a far better job with all the headphones I have compared to the CK2III. Considering that my set up is not the same as yours, its possible your CK2III does well in your rig. throw in the fact that listening is so subjective, it complicates things even more.

 To me the CTh is a superior amp compared to the Ck2III


----------



## holland

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Look..I don't want to get into a back and forth thing here..

 I just reported what I heard and my opinion. 

 I tried the best tubes I had with the CTH but the bass wasn't up to the mark when compared to the CK2III. Changing to boutique parts or some fancy tubes may do the trick..

 I did forget to mention that the bass improved ont he CTh with an RCA 5963 but lost some of the sparkle in the highs that the 12BH7 had.

 The CTH did a far better job with all the headphones I have compared to the CK2III. Considering that my set up is not the same as yours, its possible your CK2III does well in your rig. throw in the fact that listening is so subjective, it complicates things even more.

 To me the CTh is a superior amp compared to the Ck2III_

 

Heh. For someone not looking for a back and forth you sure are coming off strongly. I understand you're passionate about the CTH so strong opinions are somewhat expected.

 As far as opinions go, I never disputed yours, other than the "extreme roll-off". You may want to re-read my original posting.

 For the poster of the question, you may want to start another thread.


----------



## runeight

Perhaps this lively discussion is a matter of purpose.

 As you all know I did the redesign of the CKKIII. The purpose of this amp is a cheap, good quality, no NFB solid state amp. It is not intended for rolling anything and I am surprised if anyone can hear any difference between different O/P transistors. But because there is no NFB, I believe there could be some slight SQ differences. This amp is not designed to be extremely portable because it uses a 15-0-15 transformer.

 OTOH, the CTH is specifically designed to be both very portable and able to use a whole multitude of tubes. In this case the amp is expected to be different depending on the tube chosen. I also expected that there would be different opinions about the sound of different tubes and that folks would even prefer a different tube for different music. The goal was to make it sound very good given its size and flexibility. There is no other amp that I am aware of that can do what this amp can do in such a small space using only a single wall wart (including a compact, dual heater supply and a 95V B+ for the tube).

 So, maybe the amps are both doing what they were designed to do.


----------



## holland

You know, Alex. That was exactly what I wanted to say, and you said it so much better. Cheers to you.


----------



## sachu

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Heh. For someone not looking for a back and forth you sure are coming off strongly. I understand you're passionate about the CTH so strong opinions are somewhat expected.

 As far as opinions go, I never disputed yours, other than the "extreme roll-off". You may want to re-read my original posting.

 For the poster of the question, you may want to start another thread._

 

Holland,

 Stating a preference is not being passionate. OTOH, the only amp that I possibly will ever be passionate about is the EHHA.


----------



## holland

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Stating a preference is not being passionate._

 

Sure, but 3 times seems to be. 
	

	
	
		
		

		
			








 OK, enough with that.

  Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_OTOH, the only amp that I possibly will ever be passionate about is the EHHA._

 

I haven't heard one yet, but plan to build one soon. I don't think any of my locals have one. I hear it's good from dBel84, who has been speaking of it for quite some time. It probably needs a comparison against the Borbely (sp?) hybrid.


----------



## sachu

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I haven't heard one yet, but plan to build one soon. I don't think any of my locals have one. I hear it's good from dBel84, who has been speaking of it for quite some time. It probably needs a comparison against the Borbely (sp?) hybrid._

 

I have his EHHA on my desk right now..
	

	
	
		
		

		
		
	


	




 Compared it against the Stacker..The stacker is a very nice amp for sure, but the EHHA does some things better than the stacker and vice versa.
 These two amps are something else.

 My EHHA amp chassis is all ready and the EHHA order is on its way


----------



## holland

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I have his EHHA on my desk right now..
	

	
	
		
		

		
		
	


	




 Compared it against the Stacker..The stacker is a very nice amp for sure, but the EHHA does some things better than the stacker and vice versa.
 These two amps are something else.

 My EHHA amp chassis is all ready and the EHHA order is on its way 
	

	
	
		
		

		
		
	


	


_

 

No fair.... 
	

	
	
		
		

		
		
	


	




 *sigh* Stacker 2....is it much further, papa smurf?


----------



## tacitapproval

Ok, testing out CTH for first time. E12 trips correctly and goes red to green. TB+ at 100v, but pins 1 and 6 are at @95v each. Help needed............


----------



## runeight

There are several easy things to check before we need to do deeper debugging.

 1. Are D1L and D1R in the correct orientation with their anodes to the B+
 2. Are the opamps ICL and ICR correctly oriented in the sockets?
 3. Check all resistor values in the input stage and make sure the resistors are in the right places.

 If all of this is ok then we'll need to take some other measurements.


----------



## runeight

One more thing. Is the tube lit?


----------



## runeight

And I guess two more questions. What tube are you using and what do you have the heater voltage set at?


----------



## tacitapproval

Diodes are correct, as are the opamps.
 I double checked the input resistors and they are accurate.
 Tubes light. I have tried both a 12au7a and a 6p1n, switiching the heater accordingly.
 With the tubes inserted the e12 goes green for a second and then cut off to red. With no tube it stays green.


----------



## runeight

Could you please measure all of the tube pins with respect to SG. And also the 24V supply to be sure that we have 24V.

 Are you using all stock BoM parts?


----------



## tacitapproval

I just realized that my OG is sitting at 14v not 12. The transformer is putting out 28v not its rated 24.


----------



## runeight

Ah, this is a start. Is the LV rail 24V?


----------



## tacitapproval

I'm sorry, how do I measure the LV rail?


----------



## runeight

Easiest way is to measure both outside pins of the 24V regulator. One pin should be around 30V or more and the other at 24V. If the amp is inside the case be careful not to short anything out to the case.


----------



## tacitapproval

29.1 on one side and 28.5 on the other.


----------



## runeight

OK. Please check to see if the regulator is oriented correctly and if it is then it's probably toasted somehow. Will need to be replaced.

 Did anything unusual happen when the amp fired up? It's pretty hard to burn out one of these regs since they are current limited and thermally protected. But it can happen.


----------



## tacitapproval

Well that's foolish, I put it in backwards. If I swap it round should it still function or will I need a new one? 

 Thanks for walking me through this. I am definitely learning a lot.


----------



## runeight

It does happen. I've done things like this plenty of times. 
	

	
	
		
		

		
			





 It will probably work if you turn it around. When you power up again make the outside pin measurements right away and see what you get. If the LV is 24V then I suspect that the tube plate voltages will be about 80V.


----------



## runeight

And if the tube's plates are near 80V then measure OG. It should be half of the LV, whatever that is.


----------



## tacitapproval

Success!! Voltages check out and Music is playing! Thanks again.


----------



## runeight




----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Success!! Voltages check out and Music is playing! Thanks again._

 

awesome..congrats on getting the amp going so quick!!


----------



## tacitapproval

After a little sleep, the amp seems to run 12au7a at 12.6v with no problems, but the e12 keeps tripping on 6n1p-ev set at 6.3v. I managed to get music for a moment before the e12 cut out. I also tried two different tubes to make sure it wasn't a bad one.

 edit: 12bh7a works as well.


----------



## runeight

Are you using the stock C4L and C4R??

 Also, please check the values of R1E, R2E, and R4E.

 Thanks.


----------



## tacitapproval

For c4, I am using the wimas Wiatrob offers as an upgrade.
 The e12 resistors check out ok.


----------



## Giuss

Where to find constant current diodes?

 Is possible to use another solution? Like LM334 or discrete solution for constant current?

 Bye


----------



## runeight

Hi Giuss. I specifically used CRDs to save space. Did not attempt at all to create an alternative to them.

 Tacitapproval, we noticed some of this in one or two of the prototypes, particularly if someone used caps with long leads. But we made some adjustments and haven't seen it for a while.

 Do you have other tubes to try? To see if the problem occurs with anything other than 6n1ps.


----------



## tacitapproval

Those are the only 6.3v kind I have. I have several 12.6v versions, which so far have all worked.

 None of my caps have extended leads, but I could reflow them if it might help?

 edit: I just tried a third 6n1p and it is playing ok. I guess this may be a problem with the other tubes. Good thing I have a few of these.


----------



## runeight

Great. So you are ok now?


----------



## runeight

Quote:


  Originally Posted by *Giuss* /img/forum/go_quote.gif 
_Where to find constant current diodes?

 Is possible to use another solution? Like LM334 or discrete solution for constant current?

 Bye_

 

I guess to suggest the obvious, and not necessarily to push the products, but if you were to buy a kit you would get all the necessary components.


----------



## tacitapproval

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Great. So you are ok now?_

 

Yes. Thanks again.


----------



## tacitapproval

Ok, so I went back and tried the two 6n1p's that had caused problems with the e12, and now they play fine. What gives? I have always been a burn-in skeptic for electronics, but something is working better now without me altering anything. Any theories?

 By the way, this little amp is mighty impressive. All of the tubes have sounded quite good so far.


----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Ok, so I went back and tried the two 6n1p's that had caused problems with the e12, and now they play fine. What gives? I have always been a burn-in skeptic for electronics, but something is working better now without me altering anything. Any theories?

 By the way, this little amp is mighty impressive. All of the tubes have sounded quite good so far._

 

Is it possible they were not put in correctly the first time you tried them? They do have longer leads right compared to other tubes?

 I would suggest trying to roll those 3 tubes a few more times and check if the E12 is working fine.


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_SNIP...What gives? I have always been a burn-in skeptic for electronics, but something is working better now without me altering anything. ._

 


 Were the tubes NOS? No thporetics - Sometimes when things sit around for 20 years or so they need a little juice flowing through them to wake them up. I have seen this with some tubes (channel imbalance, etc, goes away after they burn for few hours.)

 Congrats on getting the amp up and running! Enjoy!


----------



## tacitapproval

Yes, they are NOS from the 70s, I believe. I wasn't able to try them out before, because my SOHA II is not configured for higher amperage. I suppose that is it. Glad they work


----------



## runeight

Although I am not a big believer in tube breakin, there is an important activity that takes place in the first 50 hours or so.

 Even though the tubes are evacuated they still have residual gas. And there are gases and other crude stuck onto the metals at the molecular level. When they sit for a long time they can get gassy from the small amounts of leakage that occur and from the outgassing of the residual junk in the tube.

 Over the first 50 hours the heating due to normal operation causes all this junk to be ejected from the various surfaces where it's all, eventually, collected by the getter.

 So over the first 50 hours the tube internally cleans itself and makes a pretty hard vacuum.

 It could be, although we are not certain, the the 30 year old tubes just need some runtime to clean themselves up.


----------



## TimJo

I'd say this is true, based on my experience with the NOS tubes I've tried from the late 50's and early 60's. One of them didn't make it more than 20 hours before one channel started to fade away, but the vendor is sending me a replacement. 
	

	
	
		
		

		
		
	


	




 I do have to say that rolling these old tubes brings a whole 'nuther level to listening to vinyl...

 Part of this might be the synergy between my phono preamp and the CTH. The Linto is a moving coil preamp where the coil is directly coupled to the input transistors - no loading network. I'm not sure how many companies have built this style of mc preamp because it is designed to work with very low coil output (25pW) and a specific input impedance. The Benz cart I have is a good match - the s/n ratio is incredibly low and the detail pretty amazing when driving these old tubes. Because of this it is also pretty unforgiving - your pretty much hearing the inside walls of the vinyl groove using a microscope. A record cleaner is a good thing. 
	

	
	
		
		

		
		
	


	




 I continue to be blown away by the details I am hearing for the first time in really old albums.


----------



## Forte

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_
 It could be, although we are not certain, the the 30 year old tubes just need some runtime to clean themselves up. 
	

	
	
		
		

		
		
	


	


_

 


 Yep, even my limited experience with tubes backs that up.

 The biggest change seems to be over the first few hours, but it can be a few days before a NOS tube fully reveals its true sound. Worth the wait though as they usually sound better than the new production tubes I have tried so far.


----------



## tacitapproval

So, this morning, the two 6n1p's I tried at first are again playing for a few seconds and then tripping the e12 and repeating this again and again. The other two (I have four from the same source) are ok and stable. I assume the two are just dodgy (Unfortunately, I don't have a tube tester). But, why would they not work, then work (they played stably for at least fifteen minutes a piece last night), and then not work again. The only guess I have come up with is changes in atmospheric pressure or humidity? Any other ideas? Is it possible they will work more stably if I burn them in longer?

 p.s. Sorry to thread hijack--I think I have safely determined that it is not the CTH that is at fault.


----------



## holland

Was your amp hot or cold in those situations (yesterday morning, last night, this morning)? Does the behavior change as the amp (and or tubes) warm up?

 Can you ground your input? Take a 3.5mm male to 3.5mm male adapter Tape a resistor leg across the contacts on one end and insert the other into the amp input. This grounds the inputs. Does it still trip?


----------



## tacitapproval

I went to try your suggestion, Holland, and, you guessed it, the e12 is not being tripped now. 
	

	
	
		
		

		
		
	


	




 In terms of warmness, I suppose the amp may have been on a bit longer when the tubes have worked, although I haven't enclosed it yet, so nothing is appreciably warm, save the regulator. Also, the tubes would not be any warmer as they trip the e12 right away, or don't right from a (cold) start.


----------



## Giuss

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_I guess to suggest the obvious, and not necessarily to push the products, but if you were to buy a kit you would get all the necessary components._

 


 Ok thanx, but I'm not sure if is convenient to order the kit from Italy for shipping and custom costs

 Bye


----------



## holland

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I went to try your suggestion, Holland, and, you guessed it, the e12 is not being tripped now. 
	

	
	
		
		

		
		
	


	




 In terms of warmness, I suppose the amp may have been on a bit longer when the tubes have worked, although I haven't enclosed it yet, so nothing is appreciably warm, save the regulator. Also, the tubes would not be any warmer as they trip the e12 right away, or don't right from a (cold) start._

 

I see. I was just curious if you had any cold joints. The other was to see if you were getting any spurious events happening while the amp is (externally) in a quiescent state.

 One thing, though less of a problem solving point but more of a problem identification, is if you can isolate a music track that trips the e12 consistently. Is it always in the same spot(s) where it trips?

 For the tube that does work, using the same tracks, what happens if you turn it louder? Does it trip in the same way?


----------



## tacitapproval

I think you are on the right track with the grounding. I think it is related to external devices. I say this because, I noticed that it happened one time (after a period of stability) when I printed something (printer and computer on the same outlet as the CTH). This doesn't happen with other tubes because of 6n1p's greater current draw? I will try different outlets and see if it changes.

 It doesn't follow specific music or volume. In fact, it can happen while no music is playing.


----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I think you are on the right track with the grounding. I think it is related to external devices. I say this because, I noticed that it happened one time (after a period of stability) when I printed something (printer and computer on the same outlet as the CTH). This doesn't happen with other tubes because of 6n1p's greater current draw? I will try different outlets and see if it changes.

 It doesn't follow specific music or volume. In fact, it can happen while no music is playing._

 

well apart from the hiccups with the 6N1P..how does the amp sound?


----------



## Nebby

Well I'm picking up two kits, one for myself and one for my friend. So after building them I'll have a chance to listen to a balanced CTH before I case them up


----------



## tacitapproval

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_well apart from the hiccups with the 6N1P..how does the amp sound?
	

	
	
		
		

		
		
	


	


_

 

It's fantastic. Not quite as smooth as the SOHA II, but a lot closer than its size would indicate.


----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_It's fantastic. Not quite as smooth as the SOHA II, but a lot closer than its size would indicate._

 

Yeah, that's exactly my thought too. The SOHA 2 was slightly better but for the price and the size..the CTH is quite the deal.


----------



## nsx_23

Whats the build time for one of these? Uni break coming up, so might finally get the time to build it.

 Otherwise I'll have to wait till mid-year break......


----------



## sachu

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Whats the build time for one of these? Uni break coming up, so might finally get the time to build it.

 Otherwise I'll have to wait till mid-year break......_

 

umm..lets see..about 3 hours it took me last night to populate 95% of the board. Missing a few components else it would all be done by now. 

 The case work is about half an hour to an hour at the most if you are using the plastic end plate version. The top plate takes an additional hour to two.

 Of course with Wiatrob offering pre-drilled top plates or perf tops, plus the soon to be added custom front and rear end plates, casing would be a non-issue.


 The custom plates are looking real nice too 
	

	
	
		
		

		
		
	


	





 My second CTH is going to have RCAs and a 1/4 inch jack in the small case..

 I think I can squeeze it in...we'll see


----------



## nsx_23

Ooh, custom plates. When will they be ready?


----------



## tacitapproval

Sachu, I think you are much faster than me. It took me @ six hours to populate the board and wire it--there are a lot of parts. I haven't done the casework yet, but I have the plastic ends so it shouldn't take too long.


----------



## Nebby

I just realized I don't own a uni-bit! Anyone know where to buy one with good prices?


----------



## wiatrob

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Ooh, custom plates. When will they be ready?_

 

In about a week. I'm revising the spacing and design now, will run a second prototype in a day or two. Price is TBD at this point, I'll post pictures some when they're ready.


----------



## MrSlim

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_I just realized I don't own a uni-bit! Anyone know where to buy one with good prices?_

 

The best prices seem to be on ebay. 
 This is the best deal right now I think:
4 PC STEP DRILL BITS TITANIUM tools - eBay (item 260388448407 end time Apr-07-09 11:30:26 PDT)

 I bought a 3 piece set a while back and recently purchased one of the bigger 1 3/8" ones to do some of the bigger holes. The other set max was 3/4" The deal attached includes the 1 3/8" so it would be very versatile.


----------



## holland

Quote:


  Originally Posted by *nsx_23* /img/forum/go_quote.gif 
_Whats the build time for one of these? Uni break coming up, so might finally get the time to build it.

 Otherwise I'll have to wait till mid-year break......_

 

It'll vary, depending on what you want to do. A week, working on it now and then at a slow pace should suffice.

 I'm building my second one right now, using a larger case (1602). I'm mounting them in the upper slots, so a large part of the time was in playing with how I want to mount things and how much room I have for the bits in the rear and front, and top and bottom clearance. That probably took me a day, and then mocking up a template for the front and back panels is a few hours of measuring and laying out.

 My first build was similar, in a Context Engineering case, mounting in the upper slots, playing with parts placement (what to move underneath and angle in certain ways), etc.

 If you stick with the recommended build, and putting the PCB in the bottom slots of the Hammond case, it should go fairly quick. Take your time though, replacing parts because you put them in the wrong spot is not entirely pleasant.

 Overall, a week (for uni break) should be more than adequate. If you aren't constantly out and about with friends, it should be plenty of time.


----------



## sachu

A big thanks for all those who participated in the 6N1P tube group buy..

 Those in the states should be receiving your tubes in a day or two at most and in a week for our friends abroad.

 Payment has been received from everyone. Thank you very much all. Hope the tubes light up your eyes and warm your ears.

 Cheers,
 Sachu


----------



## MrSlim

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_Well I'm picking up two kits, one for myself and one for my friend. So after building them I'll have a chance to listen to a balanced CTH before I case them up 
	

	
	
		
		

		
		
	


	


_

 

So do you have a pair of balanced headphones now, and if so what brand?
 I've been curious about the idea myself, but am also a little skittish about recabling my K601s. There has been a lot of discussion about the fact that some headphones benefit from balanced operation more than others and I'd kinda like to know in advance that I would be getting a worthwhile improvement for the effort involved.


----------



## wiatrob

I hate to be the one to disparage the idea of hooking two of these amps up balanced (as I floated the idea early on). But there are some technical hurdles due to the virtual ground levels. I think they're mentioned earlier in the thread...


----------



## holland

I think you can do it. Just leave the ground disconnected from output, but wire it connected to a ground point. Meaning the incoming interconnect needs to have 3 real inputs, +, -, and G per channel. G shouldn't be floating. The + and - should be at the same/similar DC levels and effectively cancels each other out. Take the L and R from one channel as the + and - for the headphone.


----------



## MrSlim

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I hate to be the one to disparage the idea of hooking two of these amps up balanced (as I floated the idea early on). But there are some technical hurdles due to the virtual ground levels. I think they're mentioned earlier in the thread..._

 

I hadn't thought about that, good point. Well, I know I have lot's of other things that should be occupying my time, rather than thinking about such things. 

 Loving the sound of CBC Radio 2 right now via my K601's and CTH with an Amperex 6DJ8...


----------



## holland

From AMB's Beta22 "other options" page.


----------



## MrSlim

Whew.. I reiterate my previous comment... 
	

	
	
		
		

		
		
	


	




 OOhhh.. "The Firebird" just gave me the shivers...


----------



## runeight

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_From AMB's Beta22 "other options" page.




_

 

Unfortunately, this is not quite the same situation. In AMB's case there is just ONE ground channel for both outputs. In the CTH there are, effectively, TWO ground channels and they are built in to the amp. How well the channels match depends on two things:

 1. What the exact LV is. There is variation in regs and they will not be the same. This matters because the LV determines the OG (ground channel) voltage.

 2. The actual splitter behavior (mostly determined by the TLE). These devices have tolerances too and they don't exactly split the rail in half.

 So, the OL and OR or each amp will match the OG. Two amps tied together will have a DC offset across the headphones determined by how far apart the two OG's are.

 This is not to say that it can't be done, only that some matching may be required.

 If you guys really want a balanced version the designer should design one.


----------



## holland

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Unfortunately, this is not quite the same situation. In AMB's case there is just ONE ground channel for both outputs. In the CTH there are, effectively, TWO ground channels and they are built in to the amp. How well the channels match depends on two things:

 1. What the exact LV is. There is variation in regs and they will not be the same. This matters because the LV determines the OG (ground channel) voltage.

 2. The actual splitter behavior (mostly determined by the TLE). These devices have tolerances too and they don't exactly split the rail in half.

 So, the OL and OR or each amp will match the OG. Two amps tied together will have a DC offset across the headphones determined by how far apart the two OG's are.

 This is not to say that it can't be done, only that some matching may be required.

 If you guys really want a balanced version the designer should design one. 
	

	
	
		
		

		
		
	


	


_

 

LOL, you can design one if you like. 
	

	
	
		
		

		
		
	


	




 I'm not a balanced user.

 Actually, in AMB's case, there are 2 ground channels, as that's wiring for a 6-channel Beta22.

 The + and - are taken from the same side (1 ground for that side). The DC on that one side should be offset within itself by the + and -. G is not attached, so the DC floats.

 I guess a more apropro situation is this (and less confusing though they are the same), with the M3.


----------



## TimJo

Mine arrived in the mail today. I'll be checking them out tomorrow... 
	

	
	
		
		

		
		
	


	




 Thanks again, Sachu.

  Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_A big thanks for all those who participated in the 6N1P tube group buy..

 Those in the states should be receiving your tubes in a day or two at most and in a week for our friends abroad.

 Payment has been received from everyone. Thank you very much all. Hope the tubes light up your eyes and warm your ears.

 Cheers,
 Sachu_


----------



## rds

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_If you guys really want a balanced version the designer should design one. 
	

	
	
		
		

		
		
	


	


_

 

The designer should totally do that


----------



## smeggy

Yes, and use moar tubes because they're pretty 
	

	
	
		
		

		
		
	


	




 I'm so shallow! hehe


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Yes, and use moar tubes because they're pretty 
	

	
	
		
		

		
		
	


	




 I'm so shallow! hehe_

 

heh..man you just built a SS and now you are spoiled Gary


----------



## smeggy

must..have...tooooobz!!

 and send your addy!!


----------



## wiatrob

The compatible tube list for this little jewel just keeps growing... I think it will encourage tube rolling madness. Sounds like smeggy is already infected


----------



## smeggy

I was looking over the board and sackfull of components in wonderment.... that's a lot of stuff!


----------



## Sherwood

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I was looking over the ... sackfull of components in wonderment.... that's a lot of stuff!_

 

That's what she said, Smeggy old boy.


----------



## smeggy

hehe 
	

	
	
		
		

		
		
	


	




 I'd need a microscope to read the component labels on this thing. Luckily I'm able to have it put together by younger eyes than mine.


----------



## MisterX

Here ya go. 
	

	
	
		
		

		
		
	


	




10X-20X STEREO BINOCULAR MICROSCOPE BOOM ARM + LIGHT - eBay (item 170268345984 end time Apr-29-09 16:25:03 PDT)

 Got to love the text: 

  Quote:


 INCOMPARABLY SUPERIOR TO OTHER OFFERS ON eBay!


----------



## smeggy

Yeah, that would probably do the job! 

 But then I think to myself, $170.... scope or Bijou


----------



## scompton

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_hehe 
	

	
	
		
		

		
		
	


	




 I'd need a microscope to read the component labels on this thing. Luckily I'm able to have it put together by younger eyes than mine._

 

Building the SOHA II forced me to finally buy reading glasses and the CTH looks worse.

 For the last year or so, I've had to take my glasses off to see anything within 3 feet. It's worked fine for looking at a computer screen or reading, but looking at the board and components, I needed reading glasses. I have a feeling I'm going to have to break down and get progressives or bifocals.


----------



## smeggy

Already there my friend


----------



## wiatrob

I find binocular 'scopes a bit disorienting - prefer my honking-big-helping-hands magnifier..


----------



## smeggy

need to get some of these...


----------



## Sherwood

Crazy binocugoggles, or international units of currency?


----------



## smeggy

Currency first to buy the goggles... my plan is flawless and so cunning you can pin a tail on it.


----------



## wiatrob

I was working on a clever pun about the stAMPS. FAIL


----------



## nux

Well I've just about finished my first build (of 5.. eek). All went smoothly, tested and getting the right voltage at the tubes, correct output ground etc and had a crude listen with a bunch of alligator clips and wire. Cannot find one 3.5mm to 3.5mm cable anywhere in the house, so going to buy one in the morning before I can listen to it properly =/

 Build time was about 4.5 hours for the PCB components, Another couple of hours trying to drill out the front and rear panels but stuffed it up quite a bit. Never done any casing before. Luckily I bought a 10 pack of the case ends as well so I have plenty to get it right.

 Better finished photos hopefully tomorrow, unless I get stuck listening to it in its current state which is quite likely.

 What's the best way to drill out the top tube hole?


----------



## wiatrob

As most of the kits have shipped (my apologies for the delay due to the Knob Snafu!) I'd like to reiterate that builders follow the sage advice presented many times in this thread. 

 Read and understand Alex' CTH website information.

 Take your time.

 Double (triple) check all your part values.

 Take your time!


----------



## wiatrob

Congrats! 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_What's the best way to drill out the top tube hole?_

 

Drill press with a metal hole saw. In a pinch, a hand drill with a spade bit will work. Clamp the lid tightly to a well secured block of wood and go slooow.


----------



## Coreyk78

I use hole saws for drilling larger holes on my projects, but since wiatrob was offering pre drilled tops with his kits I took the easy way out this time, hehe 
	

	
	
		
		

		
		
	


	



 That way I can't screw up and have the hole a little off center, you know, one of those things that most other people wouldn't notice, but you know it's there so you can't help staring at it?


----------



## TimJo

The other option is a stepped unibit. The nice thing about these is that they help keep things centered because with each increase in diameter, the prior size acts as a pilot hole for the next step (if that makes any sense). The biggest issue with unibits is that they are kind of expensive, but if you do much DIY builds, it pays for itself quickly. I have one that goes from 1/4 to 3/4 inches, in 1/16" increments.

IRWIN Unibit by IRWIN Industrial Tools


----------



## nux

Only problem is I'd need to get a 1.5" hole on the top, most step bits don't go that high. I'll go buy a metal hole saw tomorrow and see how I go.


----------



## TimJo

Yeah, I'd say a hole saw for sure then. Didn't realize you were going for a hole that large...


----------



## MrSlim

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Only problem is I'd need to get a 1.5" hole on the top, most step bits don't go that high. I'll go buy a metal hole saw tomorrow and see how I go._

 

This: STEP DRILL BIT 1/4 TO 1-3/8" TITANIUM BITS TOOLS - eBay (item 250404606464 end time Apr-12-09 20:34:11 PDT)

 goes up to 1 3/8", which is plenty large enough for the tubes used in the CTH. 
 In fact, it's just the right size to use a ring from a tube protector to "finish" it up, like the last pic here:
http://www.head-fi.org/forums/5527658-post438.html


----------



## wiatrob

Quote:


  Originally Posted by *Coreyk78* /img/forum/go_quote.gif 
_That way I can't screw up and have the hole a little off center, you know, one of those things that most other people wouldn't notice, but you know it's there so you can't help staring at it?_

 

As there will always be variations with drills and even tube socket center soldering - The hole is drilled a little larger than the bushing diameter so there's a little 'float' - this way you can have that 'exactly centered' look.


----------



## tacitapproval

Arghh... I cased up my CTH and now the e12 is not opening up. The led stays red. My voltages test out ok- TB+ 103v, outputs are all around 12v, pins 1 and 6 are near 80v, the tube lights up, nothing is seemingly hot or smoking. I checked the wiring on the pot and jacks and it is all ok. I guess I damaged something in the e12? Any advice on how to troubleshoot this?


----------



## wiatrob

Where did you wire SG?


----------



## tacitapproval

It's bolted to the case. Continuity seems to check out ok as well.


----------



## sachu

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Only problem is I'd need to get a 1.5" hole on the top, most step bits don't go that high. I'll go buy a metal hole saw tomorrow and see how I go._

 

DOn't go the hole saw route...its a disaster I tell you.

 Just get a round file, drill out a hole big enough to put it through and then file away.
 The hole saw will almost surely mess things up for you.

 Congrats on your first build...That was really fast considering the components had to be shipped to australia..


----------



## tacitapproval

I did some more testing. With a tube in, I am getting 11.9v on the OL and OG and 0v on OR. What did I do? This is frustrating.

 I guess I shorted OL to OG somehow.


----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I did some more testing. With a tube in, I am getting 11.9v on the OL and OG and 0v on OR. What did I do? This is frustrating.

 I guess I shorted OL to OG somehow._

 

take off the tube, meaure OL to SG and OR to SG and report back the values. 
 Can you tell me what resistors you have at R1E, R2E and R4E?

 Also values of R14L/R and R15L/R


----------



## tacitapproval

I fixed the wiring, now I am getting 12v on OG and 0v on OL and OR without a tube. 

 I have all BOM values at those positions. Keep in mind this was working fine until I did something boneheaded during the casing.


----------



## tacitapproval

So I guess I killed either the opamps or the buffer transistors?


----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I fixed the wiring, now I am getting 12v on OG and 0v on OL and OR without a tube. 

 I have all BOM values at those positions. Keep in mind this was working fine until I did something boneheaded during the casing._

 

And what was this 'boneheaded' move?

 if you have 33k in R1E and R2E and 2k in R4E, 15K each in R14 and R15 which are BOM values, we can move on to other things..

 getting 0V on OL and OR means that the relay is not tripping. 

 Try changing the opamp on the E12 along with the opamps for the input buffers..which is ICL and ICR. Then give it a shot and report back.

 Also what are you getting at Tb+ and at the plates of the tube?

 Cheers,
 Sachu


----------



## tacitapproval

I'm not sure what the fatal bonehead move was. Would shorting OG and OL damage components?

 Unfortunately, I don't have anymore TL081s.


----------



## runeight

Shorting OG to OL might do damage, but there are other suspects first.

 Change out the TL082. It could just be the opamp. If you don't have any more of these you can use OPA2134 or anything similar.

 If this doesn't fix the problem then we have other issues.

 However, Sachu is correct, if the e12 is not tripping to green then OL and OR can be anything. We'll have to measure inside the circuit. But try the opamp first.


----------



## tacitapproval

I swapped TL082 for a 2227, but still no green light.


----------



## runeight

OK. Is the 2227 a jfet input opamp? I have forgotten.

 Next text is to meaure all of the pins on the buffer opamp with respect to SG and report back. And you said that OG is 12V (or very close)?


----------



## smeggy

so I hear tell that it's a bad idea to mount the tube off the board by a few inches with wire. Is this correct and why?


----------



## runeight

It's simply that any extra wire between the tube and the board introduces opportunity for E/M to get into the signal circuit. And since the buffers in this amp have very high input impedance they will be sensitive to this, including the burst of radiation that occurs when the e12 relay turns on and off. Keeping the tube close minimizes the chances for problems. But there is no hard a fast rule.

 There is also a switching regulator on the board which generates some noise too. The closer the tube socket is to the ground plane on the board the less opportunity there is for this noise to get into audio as well. Although, IIRC, the oscillating freq of the regulator is 150kHz.


----------



## nux

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_goes up to 1 3/8", which is plenty large enough for the tubes used in the CTH. 
 In fact, it's just the right size to use a ring from a tube protector to "finish" it up, like the last pic here:_

 

Unfortunately I have something that will go around the hole which needs a 1 1/2" hole..

  Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Congrats on your first build...That was really fast considering the components had to be shipped to australia.. 
	

	
	
		
		

		
			



_

 

Cheers. I had all the parts ordered a few weeks ago as I needed a bunch of other stuff from Mouser, just had to wait on the PCB's. But Mouser's shipping is pretty amazing, I had a US$500 order on my door in 71 hours from when I ordered.

 Now to go buy the cables I need to actually hear this properly!


----------



## smeggy

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_It's simply that any extra wire between the tube and the board introduces opportunity for E/M to get into the signal circuit. And since the buffers in this amp have very high input impedance they will be sensitive to this, including the burst of radiation that occurs when the e12 relay turns on and off. Keeping the tube close minimizes the chances for problems. But there is no hard a fast rule.

 There is also a switching regulator on the board which generates some noise too. The closer the tube socket is to the ground plane on the board the less opportunity there is for this noise to get into audio as well. Although, IIRC, the oscillating freq of the regulator is 150kHz._

 

Thanks for that, I think I'll try it see if it's workable or not, I can always stick it on the board if there are problems.

 Thanks


----------



## tacitapproval

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_OK. Is the 2227 a jfet input opamp? I have forgotten.

 Next text is to meaure all of the pins on the buffer opamp with respect to SG and report back. And you said that OG is 12V (or very close)?_

 

Actually, I was wrong 2227 is a low offset bi-polar. Anyway, I know the tl082 is functional because I dropped in a cmoy and it played fine. OG is right near 12v.

 Buffer opamp pins are as follows:
 1 8v
 2 10.8v
 3 11.9v
 4 0v
 5 11.9v
 6 10.8v
 7 5.8v
 8 23.8v

 These numbers are with the tl082, by the way.


----------



## runeight

These are interesting numbers, but I can't yet tell what is broken.

 Pins 2 & 6 are connected to the splitter, OG. They both show the 11.9V that you measure there.

 Pins 3 & 5 are connected to the buffer outputs. The opamp will try to adjust its own output voltage (pins 1 & 7) so that the voltages at 2,3 and 5,6 are identical. 

 We can see that the voltages are not identical, however. They are off by 1V (11.9V vs. 10.8V). This typically happens when the opamp slams against one of its rails and can't adjust any farther. But in this case the opamp outputs are very far from the rails. They are at 8V and 5.8V. The opamps have plenty of room to maneuver, but they are not equalizing their inputs.

 So, with no headphones can you please measure the voltages on both leads of R18 on both channels. 

 Hate to run you through this but I don't know what's wrong yet.


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Thanks for that, I think I'll try it see if it's workable or not, I can always stick it on the board if there are problems.

 Thanks_

 

Smegster,

 your board is about 95% complete..took me about an hour and 45 mins. guess those 4 beers helped speed up my pace...


----------



## smeggy

Holy crap Sachu!

 now you're not just putting these bits in place with Blutac are you...


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Holy crap Sachu!

 now you're not just putting these bits in place with Blutac are you... 
	

	
	
		
		

		
		
	


	


_

 

heh..a few components are not flush to the board..pesky diodes and resistors seem to fall out sometimes..





 Will go get some resistors that are missing, the DIP sockets, tube socket from the surplus store...should be ready to fire up along with my second board later tomorrow.


----------



## smeggy

Awesome!!!

 It's so cute!


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Awesome!!!

 It's so cute!_

 

Heh..not as pretty as I could have made it...but I was moving fast on this one.
 Btw,

 DO you want me to install the BOM standard coupling caps? OR do you want me to get some fancy caps for them? Basically C4L and C4R which are 0.22uF polypropelene caps.

 There are many options...let me know. I might socket the caps in case you want to try different caps later


----------



## Nebby

eagerly awaiting my package to show up so I can get started. Best finish my buffalo build first so I have a source though!


----------



## sachu

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_eagerly awaiting my package to show up so I can get started. Best finish my buffalo build first so I have a source though!_

 

heh..my DIY DAC has been languishing for over 4 months now...waiting for 4 Jung super regulator boards to arrive from Sweden first...but man..I would love to snag a buffalo DAC


----------



## smeggy

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Heh..not as pretty as I could have made it...but I was moving fast on this one.
 Btw,

 DO you want me to install the BOM standard coupling caps? OR do you want me to get some fancy caps for them? Basically C4L and C4R which are 0.22uF polypropelene caps.

 There are many options...let me know. I might socket the caps in case you want to try different caps later_

 

I dunno, whatever is good. I have no idea what the bigger caps etc do so can't really say. I'll leave it in your drunken hands 
	

	
	
		
		

		
		
	


	




 Oh, did you ever win that tube auction you were going for or should I just order the $30 one from wherever it was?


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I dunno, whatever is good. I have no idea what the bigger caps etc do so can't really say. I'll leave it in your drunken hands 
	

	
	
		
		

		
		
	


	




 Oh, did you ever win that tube auction you were going for or should I just order the $30 one from wherever it was?_

 

Heh..will socket them and install the BOM caps for now..That's what m original one has.

 Naa that tube auction didn't go well ..another time perhaps


----------



## tacitapproval

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_So, with no headphones can you please measure the voltages on both leads of R18 on both channels. _

 

3.5mV on R18 L & R.


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Heh..not as pretty as I could have made it...but I was moving fast on this one._

 

Were those 4 beers 32 oz. each?


----------



## wiatrob

Quote:


  Originally Posted by *Nebby* /img/forum/go_quote.gif 
_eagerly awaiting my package to show up so I can get started. Best finish my buffalo build first so I have a source though!_

 

They are on the way! In facts, all kits have been shipped. Thanks all for your patience. And to Alex for an incredible design, I was rolling tubes last night... Stuck on an Amperex BB 6DJ8...


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_
 DO you want me to install the BOM standard coupling caps? OR do you want me to get some fancy caps for them? SNIP

 There are many options...let me know. I might socket the caps in case you want to try different caps later_

 

Now Sachu, I thought we were going to keep boutique cap options under the radar - I'm keeping the high heater current mod there!


----------



## tacitapproval

Ok, I've fixed my CTH and now know what my aforementioned boneheaded move was. I was using some starquad cable and and managed to get some of the thin, fibrous shielding on the top of the CTH pcb...D'oh!!! I thought I had cleaned it off ok, but apparently not. I went over it more carefully with some needle tweezers and removed some more tiny wires, which must have shorted something. Now it is back playing again. I am very sorry to keep wasting everyone's time and sincerely appreciate the indulgent help I have received.


----------



## wiatrob

Glad to hear it's working! My approach to cleanup was to use compressed air on the top and bottom of the PCB (after de-fluxing or wiring work) along with close visual inspection.


----------



## srserl

My kit was waiting at my door when I got home from work last night and it is going together smoothly. I have everything soldered, but was ready to install the heatsink. The instructions at the Cavalli Audio site says to install the regs and heatsinks, but the bom only has 1 heatsink. Does this single heatsink go on ICP? It looks like the heatsink will need some surgery to make it fit with Q2P,Q3S andQ1P nearby. Removing the bottom fin on each side should allow it to fit.

 Scott


----------



## sachu

Quote:


  Originally Posted by *srserl* /img/forum/go_quote.gif 
_My kit was waiting at my door when I got home from work last night and it is going together smoothly. I have everything soldered, but was ready to install the heatsink. The instructions at the Cavalli Audio site says to install the regs and heatsinks, but the bom only has 1 heatsink. Does this single heatsink go on ICP? It looks like the heatsink will need some surgery to make it fit with Q2P,Q3S andQ1P nearby. Removing the bottom fin on each side should allow it to fit.

 Scott_

 

yes, it is only for ICP, the 24V regulator..and yes you will probably need to do some sugery to get it in there..


----------



## wiatrob

I was able to bend both bottom fins out on one of my builds, but removing them is probably best for clearance. Carefully check vertical placement of ICP when inserted into the case WITH the sink... I ended up placing my first one a bit too high. 

 If placed correctly, the sink will clear the components, case side and top...

 Drat, I wish I had taken more pics of this on the proof build - but I sent it off to HeadphoneAddict...


----------



## nux

Well I can say that the 24v regulator will work without a heatsink for a while, I'd forgotten to put it on. I'm just getting it to fit now, I'll try and get some photos of it up later today to show how to modify the heatsink. The fins bend and snap off pretty easily which is good.

 Oh, and it sounds amazing! I tried out a few tubes yesterday, a Sylvania 12AU7, a new Electro-Harmonix 12BH7 and a Mullard 12AU7A which sounds good. Still have a few more to try out.

 Just curios, to burn in NOS tubes do you need to have something playing through it, or is it enough to just have it plugged in with the heater going?


----------



## wiatrob

Depends how much of a burn in fanatic you are. I'd say just having it fired up is enough to burn off any impurities in the envelope - but you might want pink noise 'distribute the energy across the spectrum' and give it a real excercise


----------



## tacitapproval

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Glad to hear it's working! My approach to cleanup was to use compressed air on the top and bottom of the PCB (after de-fluxing or wiring work) along with close visual inspection._

 

I still getting some infrequent, random e12 trips while listening, and I have had some transient noise in one channel. I am sure that this means I haven't gotten all of the little shielding wires off the board. Cleaning it is of course complicated by the density of components on the board, as I can't see all of the spaces between leads or even reach them. I have blown a lot of air across it, in addition to tweezing. I wonder if something like magnetic tweezers would help? Is there such a thing? What a mess.


----------



## wiatrob

Tacitapproval,

 What values did you use for R1E, R2E, and R4E? I think it was pointed out in this thread, but there were few value changes made in the BoM (2015B) posted on Alex' CTH website (R1E, R2E: 33K, R4E: 2.0K, only 1 to-220 heat sink used in the build).


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I still getting some infrequent, random e12 trips while listening, and I have had some transient noise in one channel. I am sure that this means I haven't gotten all of the little shielding wires off the board. snip_

 

Immersing the board in alcohol and more air might help locate further strays. Not to be alarmist - but stray bits of wire on a board this dense are rather risky.

 These most likely would cause a large puff of smoke and not the symptons you describe. See my previous message about e12 values.

 The intermittent noise is more interesting. Do you multiple tubes?


----------



## tacitapproval

Oh, I was working off 2015a not b. I see the relay circuit resistor changes, and will try that. Thanks for the heads up.


----------



## wiatrob

SSerl has just informed me that his ac plug doesn't match his wallwart cord. The transformers I secured for kits have 2.1mm plugs, slightly different than the 2.5mm called for by the BoM. I have both size jacks here, and it looks like I mixed up the one in SSerl's kit. 

 No excuses - but I did sort more through more than 6000 parts for this run 
	

	
	
		
		

		
			






 I'd like to encourage anyone with kit questions to ask them in the announcement thread (http://www.head-fi.org/forums/f6/cth...ilable-414932/) or better yet on the Spruce Canyon forum or directly to me via email. The goal is to keep this thread focused on build questions and issues.


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Oh, I was working off 2015a not b. I see the relay circuit resistor changes, and will try that. Thanks for the heads up._

 


 A slight change in the sensitivity of the e12 because to cover a wider range of operating conditions.


 -Bill


----------



## srserl

Sounds nice! My kit arrived Friday night, and I finished soldering the board yesterday. Last night I started to wire it up and discovered that the AC adapter plug did not fit the jack as Waitrob described above. This afternoon I hard wired everything up so I could test and I am happy to say it passed and I am now listening.

 The jack was the only real issue I had with the entire build. I also had to mod the heatsink slightly to fit, but that is always a possibility on any build and only took a minute or two.

 Buying the kit saved hours of time ordering parts, so it is a great value. I really like the perforated top option.

 Unfortunately, I won't have time to finish the case work until weekend after next. I just wanted to post my successful build experience from the new kits. That should give me enough time to find a few different tubes to roll!

 Scott


----------



## nux

Has anyone tried to mount the bi-colour LED under the tube socket? Just wondering whether to bother trying to do that, or just solder a seperate red/green LED directly on the board.


----------



## sachu

Quote:


  Originally Posted by *srserl* /img/forum/go_quote.gif 
_This afternoon I hard wired everything up so I could test and I am happy to say it passed and I am now listening.

 Scott_

 

Congrats on the build Scott.

  Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Has anyone tried to mount the bi-colour LED under the tube socket? Just wondering whether to bother trying to do that, or just solder a seperate red/green LED directly on the board._

 

I believe that's how you do it...take one LED and mount it under the tube socket..something that I am planning to do as well


----------



## tacitapproval

Well, I changed R1E, R2E, and R4E to the new BOM values. Unfortunately, this has not improved the problem I am having. The the e12 still trips sporadically. How discouraging.

 edit: Ironically, the 6n1p seems to be the most stable now (I have been playing one for about five minutes and no relay trips thus far), but the 12au7 varieties trip the e12 frequently. So, the original issue I had with the e12 a few days ago is now reversed. This has been a baffling build for me at each turn.


----------



## Forte

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Has anyone tried to mount the bi-colour LED under the tube socket? Just wondering whether to bother trying to do that, or just solder a seperate red/green LED directly on the board._

 

cfcubed built the original prototype with a bi-colour LED under the tube back here http://www.head-fi.org/forums/5362796-post91.html

 I put the red LED directly on the board and just put the green LED(Amber in my case) under the tube. Just make sure the LED leads are insulated and the LED securely fixed so it can't fall out and short out against the case.


----------



## holland

I put the led under the tube. It's not bright enough. My next one puts the led on the front panel.


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Well, I changed R1E, R2E, and R4E to the new BOM values. Unfortunately, this has not improved the problem I am having. The the e12 still trips sporadically. How discouraging._

 

Sorry to hear - we'll have to wait for Runeight to chime in with more ideas as that's the limit of my knowledge. The only other things that come to mind (pardon if I already) asked:

 What coupling caps are you using?

 Are the output devices (BC337-25, BC327-25) the same parts specified in the Bom?

 Did the e12 trip before it was cased?

 I'm stable with my proto build all this evening (using 6N1P and original e12 values.)

 Chin up, we'll get to the bottom of this.


----------



## smeggy

The tripping can be annoying, I hope mine doesn't do it too much


----------



## tacitapproval

I am using the upgade wima coupling caps from you. 

 Yes, those transistors are all from the BOM. 

 In terms of the e12, I was having trouble with 6n1ps tripping it a few days ago, but the 12 volt tubes were running no problem then. Now, the situation is reversed. 6n1p running stable for over an hour, but 12v tubes (12au7a, 5963, 6211) cause it to trip repeatedly.


----------



## wiatrob

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_
 I put the red LED directly on the board and just put the green LED(Amber in my case) under the tube. Just make sure the LED leads are insulated and the LED securely fixed so it can't fall out and short out against the case._

 

Exactly how I built my proto - with a nice bright amber led.


----------



## cfcubed

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_In terms of the e12, I was having trouble with 6n1ps tripping it a few days ago, but the 12 volt tubes were running no problem then. Now, the situation is reversed. 6n1p running stable for over an hour, but 12v tubes (12au7a, 5963, 6211) cause it to trip repeatedly._

 

Think you mentioned some shield bits falling on PCB & causing trouble.... It is possible that when that happened it zapped, or partially zapped, a sand part on the PCB. 

 Using test probes I shorted something on the 1st PCB build. And it was not enough to replace the sand I *thought* was bad (e.g. buffer TO92s). After a try at that I said scr*w it & just replaced CRDs, all TO92s in OB, E12 + splitter. And swapped out most opamps. Did this all at one time then powered it up & was fine. Worst part was placing smallish order, parts were cheap.

  Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I put the led under the tube. It's not bright enough. My next one puts the led on the front panel._

 

Yes it is. Mentioned this a couple times, that the BoM LED is not bright enough to lite tube but fine for panel. Most don't want a GREEN lit tube anyway
	

	
	
		
		

		
		
	


	




 Suggest separate LEDs OR using 3mm/5mm bicolor on front panel.


----------



## tacitapproval

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Think you mentioned some shield bits falling on PCB & causing trouble.... It is possible that when that happened it zapped, or partially zapped, a sand part on the PCB. 

 Using test probes I shorted something on the 1st PCB build. And it was not enough to replace the sand I *thought* was bad (e.g. buffer TO92s). After a try at that I said scr*w it & just replaced CRDs, all TO92s in OB, E12 + splitter. And swapped out most opamps. Did this all at one time then powered it up & was fine. Worst part was placing smallish order, parts were cheap._

 

I assume this is what happened. I would like to replace parts broadly as you recommend, but I am not sure which ones to replace. Are you suggesting I follow your list? I would hate to do all of this and not catch the suspect part.

 Out of incessant curiosity, I really want to know why the e12 is now kicking in on 12v tubes, but stable on 6v 6n1ps, in reversal of the previous situation.


----------



## cfcubed

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I assume this is what happened. I would like to replace parts broadly as you recommend, but I am not sure which ones to replace. Are you suggesting I follow your list? I would hate to do all of this and not catch the suspect part._

 

I can fire you over a list... It's essentially not caps (unless an electrolytic spewed or popped/raised its lid) & not resistors (unless they smoked or look fried) in OB, RS & e12. *BUT may be drastic given your:*
  Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Out of incessant curiosity, I really want to know why the e12 is now kicking in on 12v tubes, but stable on 6v 6n1ps, in reversal of the previous situation.
	

	
	
		
		

		
		
	


	


_

 

Yes, I'd have trouble letting that lie too
	

	
	
		
		

		
		
	


	




 And there are a number of great 6.3v heated tubes for this amp, like Amperex 6dj8/6922, PQ, BB variant of same.

 One general note WRT e12 trips - We do not expect nuisance trips during music, unless due to A/C line flux. E12 trips are not unexpected when powering on a connected source (or when/if it makes loud clicks) & sweeping volume quickly/full. 
 IOW rule out source & tube itself 1st, which we have appeared to have done here.


----------



## tacitapproval

Yeah, this relay activity is independent of source (it occurs even when nothing is connected to the CTH) and tube--I have tried several. 

 I think I'll wait for Alex (or someone else?) to chime in to triy to pin down a more specific issue, before I try a more global rebuild. But, that option is out there.

 I could almost live with this as a 6v only amp, but I want to use this as a bedside amp and the 6n1ps I have are noisy with my iems. The 12au7s are quieter.


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_same.
SNIP
 One general note WRT e12 trips - We do not expect nuisance trips during music, unless due to A/C line flux.
SNIP _

 

It is my understanding that the CRD's should limit AC line fluctuation trips in almost all except most extreme cases.

 I have terrible power here at work and do not experience any nuisance trips with the proto or proof builds.


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I could almost live with this as a 6v only amp, but I want to use this as a bedside amp and the 6n1ps I have are noisy with my iems. The 12au7s are quieter._

 

Something is up - I doubt you'll have to live with this amp in "either/or' state. Also, if you need some spare parts, I may be able to save you a little on shipping, let me know. 

 I have a few bits laying around


----------



## runeight

A situation like this can be really hard to diagnose.

 I'd replace parts in stages. First all the buffer and splitter bjts. Those are most likely to have been damaged if you had shorts on the board. It's almost impossible to tell which one(s) though.


----------



## tacitapproval

Ok, Alex, I will change out those parts. Should I throw in the e12 transistors as well? Other parts I should get, while I am at it? Other than resistors, and some caps, I don't have a lot of spare parts. 

 Bill, thanks for the offer. I will take you up on it, if you have the parts to spare?


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Bill, thanks for the offer. I will take you up on it, if you have the parts to spare?_

 

 I sent you an email.

 It actually sounds like your e12 is working properly. I'd start with the buffer Q's and work from there...


----------



## runeight

Yes, I agree with wiatrob on the e12.


----------



## keyid

Does the e12 trip without any headphones with 12au7's? 
 When i had issues with certain caps tripping e12 it would trip with Senn hd580/600 but not on k501. I would also let the e12 get steady with no phones then plug in phones, issue was solved with new bom parts. Do you have any parts above the board on sips or long leads? anything else directly touching the case like rca or pot?


----------



## tacitapproval

No, the e12 trips whether phones are plugged in or not. I am not using any long leaded parts. I am also using plastic panels, so jacks and pot are not connected to the case.


----------



## tacitapproval

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I sent you an email.

 It actually sounds like your e12 is working properly. I'd start with the buffer Q's and work from there..._

 

You have a pm.


----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_You have a pm._

 

Do you have an update on your amp? Wondering if you were able to isolate the problem.


----------



## tacitapproval

Bill sent me the BJTs and I am waiting to get them and swap them. I will report back as soon as I do.


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Do you have an update on your amp? Wondering if you were able to isolate the problem._

 


 A care package is on the way to Tacit with all new Q's - he should get it by the end of the week...


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_A care package is on the way to Tacit with all new Q's - he should get it by the end of the week..._

 

heh...now that's what I call service. I hope to have the two CTH boards on my desk come alive soon.

 Good luck with the transplants Tacit..


----------



## nux

Finished casing the first one up, hooray! You can see another three in the background ready to be cased up.

 Got through the tops with a holesaw and drill, just clamped it onto some wood and it went through pretty easily. Important to use some oil so it doesn't heat up too much, makes it cut through easier.

 Case only gets slightly warm after an hours use, so hopefully I wont have to drill any ventilation holes.


----------



## wiatrob

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Finished casing the first one up, hooray! You can see another three in the background ready to be cased up.
SNIP
 Case only gets slightly warm after an hours use, so hopefully I wont have to drill any ventilation holes._

 

Very nice to see some production builds coming together. 

 Good to hear it's not getting too hot - the large hole around the tube should help. I'd still do a hole over the 24V reg, but if it's staying cool - you're probably fine. 

 Seems there has been a bit of different experience with heat across the proto builds. Mine gets pretty warm with a full perf top, depending on tube choice.

 What tubes are you using?


----------



## HeadphoneAddict

I am not doing a full blown review of the Cavalli CTH (compact tube hybrid) - but I will post my impressions so far of its sound and a few comparisons.

 I have spent a couple of days with the CTH/Mullard short-plate and find it to be a nice detailed and warm powerful tube hybrid, with above average soundstage and no glaring negatives or complaints in the sound. My main complaints are the lack of a power switch, no RCA input on the rear, and less transportability due to the protruding 12AU7 through the top cover.

 I spent some time comparing it vs my Head-direct EF1/stock RCA clear-top 12AU7. One observation was with Giovanni Mirabassi "Prima O Poi" the song Symphomaniax - With HD600 the CTH presented more body to the trumpet, the piano was smoother/refined and more up front, and the sound was mellower overall and slightly darker. But, the sound was also fuller and more refined like you would expect from a bigger amp. In general listening to the CTH was more engaging than the EF1 with stock tube, which seemed a little more distant and presented a slightly less solid image of the instruments.

 Switching the EF1 RCA clear top to a Mullard long-plate in the EF1 resulted in the two amps coming much closer together. The EF1 picked up more body and refinement, and became more engaging as well. With the Mullard in the EF1 the treble did become a little more recessed than with the RCA, but not lacking. At this point I cannot pick one amp over the other as the two sound very similar. The volume control on the CTH is much better than the EF1, and I am now convinced that I need to send the EF1 back to have the volume control looked at.

 I also compared the CTH to the ALO/RWA Amphora which seems to have a little bit more transparency and detail and yet still has a fairly rich tube-like sound similar to the Cavalli. Yes, sound signatures are somewhat similar but they are not exact. I have not been able to compare their soundstages or bass/treble extension with test tones yet, but I can say the Cavalli has a little too much bass with the Sennheiser IE8 which sound better on the Amphora. I still don't think I would change anything about the Amphora or CTH with most headphones. With the Grado RS-1 the CTH, EF1 and Amphora also seem to come closer to each other in sound. (can't use the IE8 on the EF1 due to the volume control).

 Most of the listening has been with my iMod and portable Vcap dock as source (using Soloz 12-strand Litz-braid mini-RCA or my ALO SXC mini-RCA). The RSA P-51 Mustang was velcro'd to my portable Vcap dock, so I tried it out in comparison too. The P-51 has slightly more treble presence than the CTH or EF1 with Mullards or the Amphora, so it's not quite as mellow as them, but that is about the biggest difference. The other thing you notice is the P-51 is a little more forward and energetic or aggressive sounding, but not in a bad way. The CTH, EF1 and ALO Amphora are a little less aggressive and more refined sounding than the P-51, but the P-51 holds up well against them.

 The CTH is a good sounding amp and well worth the money and time to build one, and that is all that matters. I (and others) hate ratings, so I am going to nip the requests for one in the bud. Don't ask me. As you can see from my comparisons, it competes well vs other amps costing more, and as an added bonus it can be used with IEM while my son's Millett SSH and my EF1 cannot, due to poor volume controls. (Millett SSH not compared directly this time around)


----------



## olblueyez

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I am not doing a full blown review of the Cavalli CTH (compact tube hybrid) - but I will post my impressions so far of its sound and a few comparisons.

 I have spent a couple of days with the CTH/Mullard short-plate and find it to be a nice detailed and warm powerful tube hybrid, with above average soundstage and no glaring negatives or complaints in the sound. My main complaints are the lack of a power switch, no RCA input on the rear, and less transportability due to the protruding 12AU7 through the top cover.

 I spent some time comparing it vs my Head-direct EF1/stock RCA clear-top 12AU7. One observation was with Giovanni Mirabassi "Prima O Poi" the song Symphomaniax - With HD600 the CTH presented more body to the trumpet, the piano was smoother/refined and more up front, and the sound was mellower overall and slightly darker. But, the sound was also fuller and more refined like you would expect from a bigger amp. In general listening to the CTH was more engaging than the EF1 with stock tube, which seemed a little more distant and presented a slightly less solid image of the instruments.

 Switching the EF1 RCA clear top to a Mullard long-plate in the EF1 resulted in the two amps coming much closer together. The EF1 picked up more body and refinement, and became more engaging as well. With the Mullard in the EF1 the treble did become a little more recessed than with the RCA, but not lacking. At this point I cannot pick one amp over the other as the two sound very similar. The volume control on the CTH is much better than the EF1, and I am now convinced that I need to send the EF1 back to have the volume control looked at.

 I also compared the CTH to the ALO/RWA Amphora which seems to have a little bit more transparency and detail and yet still has a fairly rich tube-like sound similar to the Cavalli. Yes, sound signatures are somewhat similar but they are not exact. I have not been able to assess soundstage or bass/treble extension yet, but I can say the Cavalli has a little too much bass with the Sennheiser IE8 which sound better on the Amphora. I still don't think I would change anything about the Amphora or CTH with most headphones. With the Grado RS-1 the CTH, EF1 and Amphora also seem to come closer to each other in sound. (can't use the IE8 on the EF1 due to the volume control).

 Most of the listening has been with my iMod and portable Vcap dock as source (using Soloz 12-strand Litz-braid mini-RCA or my ALO SXC mini-RCA). The RSA P-51 Mustang was velcro'd to my portable Vcap dock, so I tried it out in comparison too. The P-51 has slightly more treble presence than the CTH or EF1 with Mullards or the Amphora, so it's not quite as mellow as them, but that is about the biggest difference. The other thing you notice is the P-51 is a little more forward and energetic or aggressive sounding, but not in a bad way. The CTH, EF1 and ALO Amphora are a little less aggressive and more refined sounding than the P-51, but the P-51 holds up well against them.

 The CTH is a good sounding amp and well worth the money and time to build one, and that is all that matters. I (and others) hate ratings, so I am going to nip the requests for one in the bud. Don't ask me. As you can see from my comparisons, it competes well vs other amps costing more, and as an added bonus it can be used with IEM while my son's Millett SSH and my EF1 cannot, due to poor volume controls. (Millett SSH not compared directly this time around)_

 

Hey Larry, find a Siemens E82CC or 5814A double or triple mica, you will hear details you didnt know was in your music. The German Siemens tube is *that* good. It wont have the coloring of the long plate mullard, its linear like a 7316 but the sound stage is huge and it is not just ahead of the others in detail, its waaaay ahead of the others for detail retrieval. More detail than your Cleartop and smoother at the same time. I have one now and I just bought 2 from cryoset. eBay has some but they wont be the ruggedized 5814A version. Only one I see on eBay has the triple mica's.

http://www.cryoset.com/catalog/produ...57b38e15e647ae


----------



## HeadphoneAddict

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Hey Larry, find a Siemens E82CC or 5814A double or triple mica, you will hear details you didnt know was in your music. The German Siemens tube is *that* good. It wont have the coloring of the long plate mullard, its linear like a 7316 but the sound stage is huge and it is not just ahead of the others in detail, its waaaay ahead of the others for detail retrieval. More detail than your Cleartop and smoother at the same time. I have one now and I just bought 2 from cryoset. eBay has some but they wont be the ruggedized 5814A version. Only one I see on eBay has the triple mica's.

Cryoset Online Store_

 

How about you sell me one of yours? For less...

 Actually, I am not sure I want to invest that much into the EF1, and I have to return the CTH when I am done.


----------



## olblueyez

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_How about you sell me one of yours?_

 

The Siemens tubes have become my favorite and I will be selling off a lot of my tubes in the near future. But Siemens wont be one of them. 
	

	
	
		
		

		
			





 Its hard to get a nice bassy tube with dark headphones like the 650 and most of them make for a combo that is too slow. The Siemens really opens them up. Especially if your dumb enough to have a stock cable on your Senn's. Come on Larry, get your credit card out and go to cryoset, you know you want one.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_The Siemens tubes have become my favorite and I will be selling off a lot of my tubes in the near future. But Siemens wont be one of them. 
	

	
	
		
		

		
		
	


	




 Its hard to get a nice bassy tube with dark headphones like the 650 and most of them make for a combo that is too slow. The Siemens really opens them up. Especially if your dumb enough to have a stock cable on your Senn's. Come on Larry, get your credit card out and go to cryoset, you know you want one. 
	

	
	
		
		

		
		
	


	


_

 

I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb....


----------



## olblueyez

Oh, forgot one thing, got some RCA 5814A's in the mail today, another amazing tube. Also linear but more closed in that the Siemens but this sucker has lots of weight across the board. Very nice compliment to the Siemens when you want a change. They go cheap on eBay and would pair especially well with brighter headphones, not that they dont go well with the 650, Im listening to one now and its sweet. It doesn't have any weird coloring, just even and heavy and smooth. I am convinced RCA was the only US tube maker worth a damn. If its not RCA or European then I have no interest.

 EDIT: The Gold Brand Sylvanias would be the exception to this rule, very nice tubes. Reminds me, the 5814 Sylvania GB is sweet as hell and its got a nice hump in the bass. Be a good tube for the 701.


----------



## olblueyez

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb, I will not succumb...._

 

You know how all the tube sellers have "This is the best 12AU7 ever made"? The Siemens really was the best. I have not tried the mucho bucko Tele's, I wont spend that much but aside from that I have tried them all (for the most part) and the Siemens kills them all.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_You know how all the tube sellers have "This is the best 12AU7 ever made"? The Siemens really was the best. I have not tried the mucho bucko Tele's, I wont spend that much but aside from that I have tried them all (for the most part) and the Siemens kills them all._

 

dammittohell...


----------



## olblueyez

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_dammittohell..._

 

After you hear the Siemens you will feel like taking the RCA cleartop and putting it under your wheels and rolling over it. That will be the first tube to go when I put some tubes up for sale.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_After you hear the Siemens you will feel like taking the RCA cleartop and putting it under your wheels and rolling over it. That will be the first tube to go when I put some tubes up for sale._

 

Well, the RCA cleartop was already relegated to the drawer by the Mullard Long-Plate. I'll let you know what I think about the Siemens next week, don't rub it in, or else...


----------



## olblueyez

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Well, the RCA cleartop was already relegated to the drawer by the Mullard Long-Plate. I'll let you know what I think about the Siemens next week, don't rub it in, or else..._

 

The mullard is a good tube but it was too warm and slow for my 650's, especially if your going to upsample your music. The Siemens really was a breath of fresh air.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_The mullard is a good tube but it was too warm and slow for my 650's, especially if your going to upsample your music. The Siemens really was a breath of fresh air._

 

Well, like I said, the Mullard is a little darker than the RCA, or the P-51 and Amphora. But slow it wasn't, despite it's thickness.


----------



## olblueyez

I just want ot add that the Sylvania GB 5963 blows the RCA 5814 away. Smoother, more bass weight and more open in the highs. I dont want anyone going lookin for the RCA when you could look for the GB.


----------



## olblueyez

*12AU7 and 12AU7 Variant Tube Sale!!!*

http://www.head-fi.org/forums/f44/tu...8/#post5614946


----------



## cfcubed

olblueyez - The tube impressions you post here... Are they *in* a CTH? 

 If not, perhaps a dedicated 12AU7/6922 variant impressions thread is in order? 
 Though much of your impressions may apply to the tube behavior in CTHs too... E.g. for the tubes I own & have used in CTH & you've commented on, my impressions are similar.

 Bringing this up because what amp you are using them in can be a big factor. Alex goes to great lengths to get things right for the tubes in his designs & this very much influences things.

 And I *think* we are trying to keep this thread to experiences during build, any debugging, etc. There is a tube + tweak thread and perhaps there should be a general CTH impressions thread too (as it's hard for others to find CTH impressions scattered about). IMNSHO of course


----------



## smeggy

x2


----------



## olblueyez

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_olblueyez - The tube impressions you post here... Are they *in* a CTH? 

 If not, perhaps a dedicated 12AU7/6922 variant impressions thread is in order? 
 Though much of your impressions may apply to the tube behavior in CTHs too... E.g. for the tubes I own & have used in CTH & you've commented on, my impressions are similar.

 Bringing this up because what amp you are using them in can be a big factor. Alex goes to great lengths to get things right for the tubes in his designs & this very much influences things.

 And I *think* we are trying to keep this thread to experiences during build, any debugging, etc. There is a tube + tweak thread and perhaps there should be a general CTH impressions thread too (as it's hard for others to find CTH impressions scattered about). IMNSHO of course
	

	
	
		
		

		
		
	


	


_

 

 Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_x2_

 

Next time use a private message.


----------



## cfcubed

I PMed olblueyez about this misunderstanding.... No offense intended, sorry if some was taken. Like his contribs here & elsewhere on the forums....

 Just wanted some order in the various CTH threads _(Edit: also to make it easier for people to find things w/o always having to resort to search, esp for noobs)_. It's the software developer in me I guess


----------



## lgn

[DELETE]


----------



## Nebby

Got my kit today, USPS butchered the box somewhat but everything inside survived just fine. Now it's time to have fun


----------



## olblueyez

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I PMed olblueyez about this misunderstanding.... No offense intended, sorry if some was taken. Like his contribs here & elsewhere on the forums....

 Just wanted some order in the various CTH threads (Edit: also to make it easier for people to find things w/o always having to resort to search, esp for noobs). It's the software developer in me I guess
	

	
	
		
		

		
		
	


	


_

 

Its all Good!


----------



## nux

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Good to hear it's not getting too hot - the large hole around the tube should help. I'd still do a hole over the 24V reg, but if it's staying cool - you're probably fine.

 What tubes are you using?_

 

I've also found the switchmode reg gets relatively hot, but I don't think enough to worry about. I'm keeping an eye on how hot the case is getting, just hope I don't need to drill anymore holes.

 I have a bunch of tubes I've been trying. Currently trying a GE 12AU7 short grey plates, but also have a Toshiba 12BH7A, Sylvania Long Plate 12AU7A, Mullard and MiniWatt 12AU7, Electro-Harmonix 12BH7-EH and a 6N1P-EV from the group buy.

 Any suggestions which would be the best to try? I'm a bit of a tube noob..


----------



## adamus

try them all!


----------



## Forte

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_I have a bunch of tubes I've been trying. Currently trying a GE 12AU7 short grey plates, but also have a Toshiba 12BH7A, Sylvania Long Plate 12AU7A, Mullard and MiniWatt 12AU7, Electro-Harmonix 12BH7-EH and a 6N1P-EV from the group buy.

 Any suggestions which would be the best to try? I'm a bit of a tube noob.._

 

The best tube will depend on what headphones you have, what music you like and the sound you are looking for. If I had a Mullard to try though that would be my pick, also really like the 6N1P and other Russian tubes I have tried, just remember to switch the heater to 6.3V.


----------



## tacitapproval

Well, my CTH build problems continue to persist and multiply. I got the parts from Bill (Thanks Bill). The first thing I did was replace R1E and R2E to the BOM parts, because I didn't have correct values when I changed to the updated BOM earlier and I had fashioned them out of two resistors in series to get the right figure. At first, I thought this had solved the e12 problem, as I was able to play through a song or two without the relay tripping. So, I cased it up without changing any transistors. Of course after I had, the problem reappeared. Some time after taking it back apart to address this, the wall wart I was using died. I located another power supply, and now the tube is not lighting. I am now getting @ 108v on TB+ and this same amount on pins 1 and 6. OG is at 12v and ICP is ok. What did I do now?


----------



## holland

tacitapproval. My 2nd build is having some issues as well, and I'll be looking at it. Can you measure the DC offset, and keep an eye on it. What I mean is power it on, measure the DC offset (before the e12 if you can). Watch both channels or find the one that is tripping the e12.

 What I am finding with mine is that the DC offset climbs with time, on the right channel. It bounces around, albeit slowly, but it is significantly higher than the left. The left is at a few mv at most.

 I was just wondering if your problem is similar.


----------



## TimJo

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_What I am finding with mine is that the DC offset climbs with time, on the right channel.
_

 

What kind of time frame are you seeing typically?


----------



## runeight

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Well, my CTH build problems continue to persist and multiply. I got the parts from Bill (Thanks Bill). The first thing I did was replace R1E and R2E to the BOM parts, because I didn't have correct values when I changed to the updated BOM earlier and I had fashioned them out of two resistors in series to get the right figure. At first, I thought this had solved the e12 problem, as I was able to play through a song or two without the relay tripping. So, I cased it up without changing any transistors. Of course after I had, the problem reappeared. Some time after taking it back apart to address this, the wall wart I was using died. I located another power supply, and now the tube is not lighting. I am now getting @ 108v on TB+ and this same amount on pins 1 and 6. OG is at 12v and ICP is ok. What did I do now?_

 

Let's just try to fix one thing at a time. Measure with respect to SG what are voltages at pins 4 & 5 on the tube socket?


----------



## tacitapproval

0v on pin 4 and 5.


----------



## tacitapproval

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_tacitapproval. My 2nd build is having some issues as well, and I'll be looking at it. Can you measure the DC offset, and keep an eye on it. What I mean is power it on, measure the DC offset (before the e12 if you can). Watch both channels or find the one that is tripping the e12.

 What I am finding with mine is that the DC offset climbs with time, on the right channel. It bounces around, albeit slowly, but it is significantly higher than the left. The left is at a few mv at most.

 I was just wondering if your problem is similar._

 

Once I get it back to the state it was in, assuming I can, I will measure the offset.


----------



## runeight

There is no heater voltage from the heater supply.

 My first guess would be to check all of the connections in the supply and the continuity of the chokes. They should have very low resistance across their leads.

 If the chokes are good the switching reg has probably burnt out. Why I don't know. Did you initially put your diodes in backwards or was that someone else? I'm losing track.


----------



## sachu

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_If the chokes are good the switching reg has probably burnt out. Why I don't know. Did you initially put your diodes in backwards or was that someone else? I'm losing track. 
	

	
	
		
		

		
		
	


	


_

 

heh..that was me Alex..had D4P in wrongly..Q1P is burning up, making R7S burn like an LED into ash..


 Also having problems with the E12 on my other board. getting OR->SG, OL->SG as 2.5volts and OG-> SG at 1.5volts. 

 All other voltages on this board checks out though. The E12 trips within 2 seconds but the voltages are off at the output.


----------



## tacitapproval

The chokes are good. I guess I need a new ICH.

 I am losing track of all the problems I have had as well... But, no, I didn't put the diodes in wrong. I guess the ICH got shorted somehow, in all the taking apart and poking and prodding I have done. Could it take out a wallwart with it?


----------



## runeight

Oh yeah, I remember now. You may have had some fine wires on the top of the board.

 The switching reg could possibly take out the wall wart if it is causing too much current draw. There may be other components that are bad too, but given the design of this supply, I would say that they are ok.

 You might want to check all of the diodes in the heater rectifier just to be sure.


----------



## tacitapproval

Ok, I will check the diodes and replace the regulator.


----------



## nux

I would also check all the solder pads on the bottom of the board. Some of the pads are very close together and may touch, especially near Q4E/Q5E.

 And do all testing before casing it. I mounted the fuse holder in the back panel and soldered that to the two switch points, and tested the board before wiring the front I/O and pot for HT+ and OG and offsets.

 I can say however that all 5 of my builds worked first time, so the design definitely works! Just have 2 left to fully case up now.


----------



## sachu

Alex, On my board, I removed the regulator, replaced Q1P and Q2P and turned on the amp. 

 Q1P is not burning out. So the problem is not with the power supply it seems.

 R7S has burnt out twice now along with Q1P. Perhaps something is up in the splitter circuit. 
 What do you make of R7S burning up?


----------



## holland

Quote:


  Originally Posted by *TimJo* /img/forum/go_quote.gif 
_What kind of time frame are you seeing typically?_

 

about 5 mins. I've replaced all my transistors in the right buffer and haven't timed it, but it does still go up in a small bouncy way and after a certain point of time it starts to bounce in larger steps. feel free to PM me as I figure it'll take me another week before I can get back onto this. I think I need to get this on my scope. I'm still away and I've completely lost all sense of time (vacation mode).


----------



## zkool448

Got my kit from wiatrob and looking to spend some time building it this week, however before I start welding parts on the board do I need any heads up? 

 I know nux had already built like 20 of them but just wanted to make sure


----------



## sachu

Quick update: 

 I have my production board running now...turns out it was a stupid mistake of me forgetting to install R9S
	

	
	
		
		

		
		
	


	




...popped that in and its making music.

 Now the last of the proto boards remains.going to take quite a bit of surgery..gonna get to it tomorrow.


----------



## cfcubed

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_ < snip >
 I can say however that all 5 of my builds worked first time, so the design definitely works! Just have 2 left to fully case up now._

 

That's great... This would support Alex amending the line In every instance during the prototype phase where the builder has put the right parts in the right places with the correct orientation the amp has come alive on first power up to include production PCBs
	

	
	
		
		

		
		
	


	




 And its great we have another helper... Five CTHs... Wondering if some are gifts or may we see a couple up for sale? I know there are a few that want a CTH but are not builders...


----------



## nux

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_And its great we have another helper... Five CTHs... Wondering if some are gifts or may we see a couple up for sale? I know there are a few that want a CTH but are not builders..._

 

Three are for friends, two for myself. May possibly sell one of mine when I'm done trying tubes out to cover some costs, as it was going to be for another person but they pulled out.


----------



## wiatrob

All- I'm out of town for a week so if anyone needs spares it'll take a bit of time. The first set of custom panels showed up in The mail minutes before I left. Thy look great. 

 I'll get some pics posted when I return. Good luck with your builds...


----------



## runeight

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Three are for friends, two for myself. May possibly sell one of mine when I'm done trying tubes out to cover some costs, as it was going to be for another person but they pulled out._

 

nux, I am amazed that you built five of these. You must have a steady hand and a great deal of patience. 
	

	
	
		
		

		
		
	


	




 So, how do your friends like them?


----------



## nux

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_nux, I am amazed that you built five of these. You must have a steady hand and a great deal of patience. 
	

	
	
		
		

		
			





 So, how do your friends like them?_

 

Yep, a lot of patience and time! One was picked up last night, I'll let you know their impressions.

 Is anyone else from Aus building one? If anyone in Australia is needing some tubes, I have amassed about 30 compatible tubes and would be happy to sell a few for what I paid for them.


----------



## sachu

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Yep, a lot of patience and time! One was picked up last night, I'll let you know their impressions.

 Is anyone else from Aus building one? If anyone in Australia is needing some tubes, I have amassed about 30 compatible tubes and would be happy to sell a few for what I paid for them._

 

heh..do you have a photo of the 5 builds together completed?


----------



## nux

Unfortunately not, I'll take a picture of the four I still have when I case up the last one


----------



## rds

I wanted to confirm that the stability issues using Sonicap gen II coupling caps in this amp have been resolved. I was told that some resistors values in the e12 were changed to support these caps. Is that right?


----------



## sachu

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I wanted to confirm that the stability issues using Sonicap gen II coupling caps in this amp have been resolved. I was told that some resistors values in the e12 were changed to support these caps. Is that right?_

 

I believe that is true..there are a few prototypers who are using those caps or have rolled them on their amps


----------



## Forte

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I wanted to confirm that the stability issues using Sonicap gen II coupling caps in this amp have been resolved. I was told that some resistors values in the e12 were changed to support these caps. Is that right?_

 

Yes, changes were made to the E12 values but not specifically for those caps(C4L/R). The changes were made to improve stability in general, there were several different circumstances which were causing the E12 to trip not just coupling caps with long leads. 

 I have had Sonicaps in my build for around a month now with no problems, Well worth the extra cost for the improved SQ and detail.


----------



## rds

thanks for the help guys. I have some gen IIs on the way.

 I just got my kit with the perforated top from Spruce Canyon Labs and it looks great. Everything is very nicely packaged too.

 ...such a cool little amp


----------



## wiatrob

Wait untill you hear it!


----------



## zkool448

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_...such a cool little amp 
	

	
	
		
		

		
		
	


	


_

 

yeah, i was impressed when I saw how compact the pcb was and the amount of parts 
	

	
	
		
		

		
		
	


	




 The build is going smoothly so far (_read_: no questions so far!)


----------



## smeggy

Nice assembly rig!


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Nice assembly rig!_

 

Perhaps, but we're *really* waiting to see what kind of casework his CTH gets


----------



## sachu

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Perhaps, but we're *really* waiting to see what kind of casework his CTH gets
	

	
	
		
		

		
		
	


	


_

 

heh..am really waiting for see that too..as well as what case Smeggy has got cooking for his CTH..will be shipping his board is out to him end of the week, requiring only casework.


----------



## smeggy

zk will eat my build for lunch


----------



## cms5423

For those who have built this--About how much did this amp cost to build? And What case did you use for it? Thanks very much


----------



## sachu

Quote:


  Originally Posted by *cms5423* /img/forum/go_quote.gif 
_For those who have built this--About how much did this amp cost to build? And What case did you use for it? Thanks very much 
	

	
	
		
		

		
		
	


	


_

 


 Cost for parts and all is about 150$ + extra for upgraded components (caps, pots, RCA jacks, wallwart, etc)

 Used the longer case for my build..also have a smaller case but that board has a lot of problems with it and is undergoing debugging..


----------



## cms5423

Hmm, may have to go the millet starving student hybrid rout then, 150 is just a bit much


----------



## cfcubed

Quote:


  Originally Posted by *cms5423* /img/forum/go_quote.gif 
_For those who have built this--About how much did this amp cost to build? And What case did you use for it? Thanks very much 
	

	
	
		
		

		
		
	


	


_

 

Don't think you can do much better than the link you see atop of the CTH board page

 @ sachu That proto board _was_ working fine at one time, if I remember correctly... Didn't some tinkering precede the problems on it?
 It's quite tempting to see what can be done with & to a CTH, but confines are very tight on the board. And its quite a complex amp in that 3" x 5" space.

 My hats off to nux for seeming to have built 5 that work right off the bat, even tho he did have quite a bit of elect experience. I _think_ he went std BoM on them & that helped.

_Edit: Hmm, may have to go the millet starving student hybrid rout then, 150 is just a bit much_
 For your budget maybe, but not for what this amp is
	

	
	
		
		

		
		
	


	




 Perhaps we'll see ya building one a bit further down the road....


----------



## sachu

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Don't think you can do much better than the link you see atop of the CTH board page

 @ sachu That proto board was working fine at one time, if I remember correctly... Didn't some tinkering precede the problems on it?
 It's quite tempting to see what can be done with & to a CTH, but confines are very tight on the board. And its quite a complex amp in that 3" x 5" space.

 My hats off to nux for seeming to have built 5 that work right off the bat, even tho he did have quite a bit of elect experience. I think he went std BoM on them & that helped._

 

I went standard BOM too..a misplaced diode first started smoking, replacing that worked for a bit. After 2 mins of music more burning smell. Possible problem with the splitter, but could be the buffer as well.
_edit:waiting for parts to arrive before I can debug further_

 My third build,uses Jantzen audio caps, and a production board is working fine and that is making its way to Smeggy tomorrow.


----------



## tacitapproval

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_tacitapproval. My 2nd build is having some issues as well, and I'll be looking at it. Can you measure the DC offset, and keep an eye on it. What I mean is power it on, measure the DC offset (before the e12 if you can). Watch both channels or find the one that is tripping the e12.

 What I am finding with mine is that the DC offset climbs with time, on the right channel. It bounces around, albeit slowly, but it is significantly higher than the left. The left is at a few mv at most.

 I was just wondering if your problem is similar._

 

I got the switching reg from digikey today and that was the problem with the heater. Unfortunately, the e12 trips remain--although, I am listening to it as I type this and the relay has gone off only once in about 15 to 20 minutes. It is tantalizingly close to being fully stable. Drats.

 I guess I will procede with swapping the output and splitter transistors next.

 Holland - I measured the offset on both channels, but I don't see any steady increase. Of course, I didn't have the meter on it when the last relay throw happened, to see what the reading was--see above. The numbers jump around some, but are pretty low; single mVs. It does occur to me that I have heard some popping on, I think, the right side before the e12 kicks in, which I guess maybe caused by offset? Of course, it is not doing it now--damn confounding problems that are not even problematic when they are supposed to be!


----------



## wiatrob

Single mVs is normal (really god actually). It doesn't sound like you have the same symptom as Holland.

 Was the 'pop' you heard similar in intensity to the one heard when you power off the amp with 'phones plugged in? Maybe try replacing the right channel buffer Q's first...


----------



## tacitapproval

The pops are like that, but somewhat softer. I will try the right side first--fingers crossed.


----------



## rds

Is the consensus that we don't need a standoff under the tube for this board?


----------



## cfcubed

@ tacitapproval - Sorry if this was mentioned, but what tube(s) have you tried? It's not beyond possibility that a questionable tube could be causing this...

 @rds - *No standoff is necessary*, but as with all electronics best to get heat out of the case if it is easy to do so. I like my projects < 60C, preferably < 55C internally.

 Not having a socket saver handy (or even knowing they existed
	

	
	
		
		

		
		
	


	




 , in my 2nd CTH I made my own:


----------



## tacitapproval

cfcubed - I have tried a variety of tubes--it is not tube dependent. Although, different tubes seem to trigger it more or less.

 Speaking of which, I was able to watch the offset numbers on a 12bh7, which seems to trigger the problem more than some. It is definitely on the right side. The left is pretty consistently between 2-5mV. The right will swing between positive and negative DC, generally staying low, but sometimes jumping up to as much as 75mV in my brief observation and triggering the e12. This must also confirm the distorted/popping noises I hear in the right side at times. Unfortunately, I changed out Qs4-9R and this has not affected the problem. Any thoughts out there on what to try next?


----------



## wiatrob

Do you have a spare TL082 you might swap out?


----------



## tacitapproval

It's not that opamp, I tried that earlier on.


----------



## zkool448

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Perhaps, but we're *really* waiting to see what kind of casework his CTH gets
	

	
	
		
		

		
		
	


	


_

 

 Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_zk will eat my build for lunch 
	

	
	
		
		

		
		
	


	


_

 

nice... not to put any pressure eh? 
	

	
	
		
		

		
		
	


	




 BTW, this might be a dumb question. In the assembly notes, it says "Do not install D5H." Maybe I didn't look hard enough can't seem to find any reference on why, and/or when I should install D5H?


 .


----------



## keyid

I believe you install d5h after putting all the flat parts so you can easily turn the board upside down and not have d5h protrude out.


----------



## nux

Yep, you need D5H. The instructions should maybe say "Do not install D5H yet". If you read on it says to install it in step 5.


----------



## zkool448

Ahhhh... thanks. I'm bad at always trying to read too much into things 
	

	
	
		
		

		
		
	


	




 I've got most of the board populated and now I have to squeeze in D5H <sigh>


----------



## smeggy

Good luck with it, at least you know where D5 lives, I couldn't make out any of it


----------



## endless402

received today


----------



## cfcubed

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_I've got most of the board populated and now I have to squeeze in D5H <sigh>_

 

Just wanted to say somewhere that one reason D5H + its leads are so large (3A) is because we sized it to survive a short in the heating circuit. 

 The smaller, easy-to-fit 1N5818 (1A) works perfectly fine but would be the weak link in case of a short in heater circuit.


----------



## Coreyk78

I ran into a bit of a problem with my CTH and haven't really had the time to diagnose it yet. I powered it up for the first time and after a little bit the e12 switched from red to green and the tube lit up so I figured it must be ok. I turned my back to grab my phones so I could give it a listening test and then, pow! C10P vented itself... I've exploded caps before, but that was because I screwed up and reversed the polarity on the cap. I know that I installed C10P with correct polarity. 

 Just for fun I tried replacing C10P with another cap I had, and tried a different tube, just in case that had anything to do with it. Same thing happened though, the e12 switched to green, but I was watching C10 closely and I could see the top of the can start to swell so I quickly turned it off. 

 I haven't had time to really dig into it, the first possibility that came to mind was a reversed diode, but a quick inspection of the board didn't reveal any that were reversed, that is assuming that I'm correct and that the body of the diode goes where the circle is silk screened on the board right? 

 Any advice on where to start looking for my problem?


----------



## adamus

yes, the body of the diode sits in the circle, and the 'stripe' should be facing upwards.


----------



## cfcubed

Coreyk78, and everyone building this for that matter, please double-check CTH info from the official site & your installed parts against the BoM, etc.
Especially the *entire* board assembly page *before building and esp before powering up your CTH*. We're trying to emphasize this whenever & whereever we can. 

 When proper parts are put in proper places with correct polarity & there are no solder bridges/wire bits around, things work.


----------



## adamus

heres my build so far. just waiting on the bushing, wiring + smoke test!


----------



## nux

Quote:


  Originally Posted by *Coreyk78* /img/forum/go_quote.gif 
_Just for fun I tried replacing C10P with another cap I had, and tried a different tube, just in case that had anything to do with it. Same thing happened though, the e12 switched to green, but I was watching C10 closely and I could see the top of the can start to swell so I quickly turned it off. _

 

Are you using a 160V+ rated capacitor to replace it with? C10P is a smoothing capacitor for the ~100V supply.

 And am I the only person with working amps


----------



## runeight

Quote:


  Originally Posted by *Coreyk78* /img/forum/go_quote.gif 
_I ran into a bit of a problem with my CTH and haven't really had the time to diagnose it yet. I powered it up for the first time and after a little bit the e12 switched from red to green and the tube lit up so I figured it must be ok. I turned my back to grab my phones so I could give it a listening test and then, pow! C10P vented itself... I've exploded caps before, but that was because I screwed up and reversed the polarity on the cap. I know that I installed C10P with correct polarity. 

 Just for fun I tried replacing C10P with another cap I had, and tried a different tube, just in case that had anything to do with it. Same thing happened though, the e12 switched to green, but I was watching C10 closely and I could see the top of the can start to swell so I quickly turned it off. 

 I haven't had time to really dig into it, the first possibility that came to mind was a reversed diode, but a quick inspection of the board didn't reveal any that were reversed, that is assuming that I'm correct and that the body of the diode goes where the circle is silk screened on the board right? 

 Any advice on where to start looking for my problem?_

 


 Coreyk78, there are only three ways that this can happen:

 1. C10P is in backwards. I know you checked for this, but it would be good to verify again using website information

 2. C10P is a 100V cap instead of 160V

 3. One or more didoes are in upside down or in the wrong places.


----------



## cfcubed

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_And am I the only person with working amps 
	

	
	
		
		

		
		
	


	


_

 

Not by a longshot
	

	
	
		
		

		
		
	


	




 Think there are about a dozen or so others working fine (proto + prod PCBs).


----------



## Coreyk78

Ok, well then the voltage is the problem if it's supposed to be a 160v cap. For some reason I had a 1000uF 50v cap in that position, problem easily solved on my next mouser order.

 Also, I look at Adamus' pictures and I see a 1000uF 50v cap at C10P, so are we both wrong?


----------



## sachu

Yep...looks like both of you have C5P and C10P mixed up

 C5P = 1000uF 50V
 C10P = 100uF 160V


----------



## Coreyk78

oops, haha, well at least it should be an easy fix. I have an extra panasonic FM 1000uF 50v cap at home that I coud use for C5P so I wouldn't even have to order anything, but it's probably too fat to fit in the little hammond enclosure since I think it has a 16mm body, I'll have to check it out when I get home.


----------



## tacitapproval

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_cfcubed - I have tried a variety of tubes--it is not tube dependent. Although, different tubes seem to trigger it more or less.

 Speaking of which, I was able to watch the offset numbers on a 12bh7, which seems to trigger the problem more than some. It is definitely on the right side. The left is pretty consistently between 2-5mV. The right will swing between positive and negative DC, generally staying low, but sometimes jumping up to as much as 75mV in my brief observation and triggering the e12. This must also confirm the distorted/popping noises I hear in the right side at times. Unfortunately, I changed out Qs4-9R and this has not affected the problem. Any thoughts out there on what to try next?_

 


 Bump on this. Anybody?


----------



## zkool448

tacitapproval, sorry to hear about you're ongoing issue with your build. I really hope you get it sorted out soon. I brought mine up and with a bit of luck on my side lately my CTH came to life without any issues. 

 adamus, that's quite a nice build you got there - congrats!

 The only changes I made is I socketed the LED pads, I want to route wires for the E12 LED to go somewhere on the panel. I must've lost the three 100R resistors (R18L, R18R, R9S), so I picked some up from my local electonics shop and used 1/4W metal films instead of 1/8W (it's all they had). 

 Sadly I'm no expert in giving impressions and pardon my french but, this little guy has some major screw balls! IMO it holds its own alongside my SOHA II and like the fact that I (no audiophile experience whatsoever) can actually hear the subtle difference in sound as I swap the tubes. Anyway I'll let adamus and other experts share their own comments and impressions.

 ...time to enjoy and listen to some tunes


----------



## MrSlim

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Bump on this. Anybody?_

 

This sounds like a servo problem in the buffer. IC1 is supposed to compensate for any DC offset, to keep it as close to zero as possible. What if you try swapping IC1L and IC1R and see if the problem changes channels.


----------



## MrSlim

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_tacitapproval, sorry to hear about you're ongoing issue with your build. I really hope you get it sorted out soon. I brought mine up and with a bit of luck on my side lately my CTH came to life without any issues. 

 adamus, that's quite a nice build you got there - congrats!

 The only changes I made is I socketed the LED pads, I want to route wires for the E12 LED to go somewhere on the panel. I must've lost the three 100R resistors (R18L, R18R, R9S), so I picked some up from my local electonics shop and used 1/4W metal films instead of 1/8W (it's all they had). 

 Sadly I'm no expert in giving impressions and pardon my french but, this little guy has some major screw balls! IMO it holds its own alongside my SOHA II and like the fact that I (no audiophile experience whatsoever) can actually hear the subtle difference in sound as I swap the tubes. Anyway I'll let adamus and other experts share their own comments and impressions.

 ...time to enjoy and listen to some tunes 
	

	
	
		
		

		
			








_

 

Nice job Z. So.. since you have a SS and the CTH, you can give us a nice, objective comparison between them.. Something that has been discussed before.


----------



## zkool448

oh geez... as I mentioned I don't really have what you experts call "trained ears" not too mention a total hp noob 
	

	
	
		
		

		
		
	


	




 ...but If you'll insists, i'll do my best and give an objective comparison of the two once I get the CTH fully burned in (just like my MSSH).

 I also have to build me this A/B box by danobeavis first since it's probably that only way I can distincttively identify their similarities and/or differences.


----------



## tacitapproval

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_This sounds like a servo problem in the buffer. IC1 is supposed to compensate for any DC offset, to keep it as close to zero as possible. What if you try swapping IC1L and IC1R and see if the problem changes channels._

 

Thanks for the suggestion, I am not sure I understand though. IC1 is a dual opamp. And, as I mentioned, I have checked this part and it is not the tl082 that is at fault. I have also swapped ICR and this is not the problem. What else could account for sporadic offset on the right side?


----------



## nux

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_I also have to build me this A/B box by danobeavis first since it's probably that only way I can distincttively identify their similarities and/or differences._

 

That's the next thing I want to build too! That way I can better compare between different tubes using two CTH's.


----------



## Coreyk78

Fixed mine. Switched the caps around and its working beautifully now 
	

	
	
		
		

		
		
	


	




 thanks guys!


----------



## olblueyez

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_That's the next thing I want to build too! That way I can better compare between different tubes using two CTH's._

 

I recommend you listen using one tube with your favorite tracks for a week or two and then roll in a new tube. Flipping back and fourth will just confuse matters. Just a suggestion.


----------



## sachu

Quote:


  Originally Posted by *Coreyk78* /img/forum/go_quote.gif 
_Fixed mine. Switched the caps around and its working beautifully now 
	

	
	
		
		

		
		
	


	




 thanks guys!_

 

nice!!..


----------



## wiatrob

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_heres my build so far. just waiting on the bushing, wiring + smoke test!_

 

Looking good, and it will be so much more so with the bushing, which is on the way!


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Looking good, and it will be so much more so with the bushing, which is on the way! 
	

	
	
		
		

		
		
	


	


_

 

Bill, he has C5P and C10P swapped..he needs to set that right before turning on


----------



## Forte

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_I also have to build me this A/B box by danobeavis first since it's probably that only way I can distinctively identify their similarities and/or differences._

 

I take it from that that these two amps are very close in performance and sound? 

  Quote:


  Originally Posted by *Coreyk78* /img/forum/go_quote.gif 
_Fixed mine. Switched the caps around and its working beautifully now 
	

	
	
		
		

		
		
	


	




 thanks guys!_

 

Congratulations 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_I recommend you listen using one tube with your favorite tracks for a week or two and then roll in a new tube. Flipping back and fourth will just confuse matters. Just a suggestion. 
	

	
	
		
		

		
		
	


	


_

 

x2 Excellent advise. I started out swapping tubes and headphones constantly and started to think all tubes sounded pretty much the same with only a slight variation. Its only after listening to a variety of music that you can really appreciate what a particular tube has to offer.


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Bill, he has C5P and C10P swapped..he needs to set that right before turning on_

 

Except for that! Those devilish zeros...


----------



## zkool448

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Bill, he has C5P and C10P swapped..he needs to set that right before turning on_

 

haha, it's quite easy to make that mistake, I almost did it too -- perhaps need to make one of the caps Nichicon 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_I take it from that that these two amps are very close in performance and sound?_

 

nope, sorry didn't mean to leave that impression. I wanted to say was i first need to build a true A/B device that allows to switch amps 'on-the-fly' easily before I can subjectively hear their differences. My initial impression though is that the CTH and SS millett do not sound alike to my ears. The SS has warm, tubey like sound and much deeper bass while the CTH sounds more detailed, accurate and good channel separation with very sharp mids/highs (but not bright).. am very happy with it. 

 I'm currently using a Russian 61NP NOS tube which I'm going to let burnin for a bit.


 .


----------



## MrSlim

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Thanks for the suggestion, I am not sure I understand though. IC1 is a dual opamp. And, as I mentioned, I have checked this part and it is not the tl082 that is at fault. I have also swapped ICR and this is not the problem. What else could account for sporadic offset on the right side?_

 

Oops, my mistake, I looked at the schematic and didn't check the parts layout... 
 It might be worthwhile measuring the voltage on the input and output of C4L and R, the interstage coupling cap and compare the two channels. That might help determining if the input stage is at fault or it's something in the buffer. 

 Runeight would have to comment on this, but I'm wondering if a bad D2(R) might cause this? It is supposed to provide a constant current source for the upper half of the buffer, and the servo opamp is used to adjust the lower current source to compensate for variations between the parameters of the upper and lower transistors, to end up with close to zero DC offset at the output.

 Also, have another look at all your solder joints, in case you have a cold/bad one that is causing you issues.


----------



## MrSlim

Hey Bill, I wanted to let you know my package arrived this week, and I installed the perf top on my proto.. It looks great and runs much cooler too. I probably won't be doing the second CTH for a while though. I have a couple of SOHA+Jisbos to get done, and some major studying for a CISSP exam coming up in June..


----------



## rds

I was wondering how much current is going to the e12 LEDs right now and if it would be possible to adjust this bias to get something like 10-15mA to better light up a tube LED?


----------



## olblueyez

12AU7 tubes do need a little help in the glow department. Make it orange if you can, it only proper.


----------



## adamus

thanks for spotting the error. that's why I always sort pics before turning on.


----------



## cfcubed

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_ < snip > The SS has warm, tubey like sound and much deeper bass while the CTH sounds more detailed, accurate and good channel separation with very sharp mids/highs (but not bright).. am very happy with it._

 

One of the really nice things about this amp is the ability to contour its sound to your tastes/cans. TimJo & others have good posts in this regard.

 Primarily this is done by rolling tubes. E.g. if more bass Amperex 6dj8 may do the trick (esp for rock/alt), while Siemens chrome plate seems more flat, detailed & accurate. Those are only a couple of my impressions, there are quite a few others in this thread & the CTH Tube & Tweaks thread.

 Another way to change the sound of the amp is altering the only caps in the primary signal path; C4s. E.g. I've found Amperex 6dj8 w/Mundorf S+O C4s too lush/tubey/heavy/bassy for my fav D2000s (great for DT-880s tho) & plan to pull the S+Os & try Sonicaps. 
 So cap rolling is another option esp. in larger-than-stock cases. But due to the tight confines, the CTH _may_ be sensitive to cap placement, lead length so tube rolling is primary. 

 IMO those used to "tubey" sound may be initially surprised by the detail, accuracy, etc. of this amp. And after getting used to that may not want to forgo it
	

	
	
		
		

		
			





 And options for contouring the sound are always there too.

 Glad you are liking it.


----------



## tacitapproval

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Oops, my mistake, I looked at the schematic and didn't check the parts layout... 
 It might be worthwhile measuring the voltage on the input and output of C4L and R, the interstage coupling cap and compare the two channels. That might help determining if the input stage is at fault or it's something in the buffer. 

 Runeight would have to comment on this, but I'm wondering if a bad D2(R) might cause this? It is supposed to provide a constant current source for the upper half of the buffer, and the servo opamp is used to adjust the lower current source to compensate for variations between the parameters of the upper and lower transistors, to end up with close to zero DC offset at the output.

 Also, have another look at all your solder joints, in case you have a cold/bad one that is causing you issues._

 

Thanks again. As to your first suggestion on C4, how would I accomplish this physically? Forgive my noobiness, but I am not sure how I would go about measuring these two. I did swap out C4R to see if that would help, but it did not.

 On the D2, I measured both L and R and the readings are similar with the diode setting on my DMM. This was not under power. Is it possible that D2R is bad even though it reads near D2L. I mean the problem only occurs periodically, so the part must work most of the time, no?

 I have tried to go over all the joints on the right side buffer. I also measured all the resistors there, and double checked all the wiring. 

 Earlier, Alex had mentioned swapping Qs in the splitter. I guess I will try this next, although I wonder that this would produce a problem only on the right side. I'm not sure.

 What other parts would be worthwhile to swap as potentially problematic?


----------



## MrSlim

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_oh geez... as I mentioned I don't really have what you experts call "trained ears" not too mention a total hp noob 
	

	
	
		
		

		
		
	


	




 ...but If you'll insists, i'll do my best and give an objective comparison of the two once I get the CTH fully burned in (just like my MSSH).

 I also have to build me this A/B box by danobeavis first since it's probably that only way I can distinctively identify their similarities and/or differences._

 

I like clean and simple, and Beavis' box is certainly that, but I have to warn everyone about a change you will have to make to the build instructions to use it with the CTH (and any other amp that uses a VIRTUAL GROUND(in the CTH it floats at about +12V) on the output). His wireing instructions suggest that you connect all the grounds together. That would be a no-no, since you would be connecting real ground and +12 V together. 
 You should only connect the input ground to Buss A and Buss B Send, and connect the Output Ground to Buss A and B Receive. I'll email him about his also, so he changes his site..


----------



## cfcubed

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_ < snip >
 What other parts would be worthwhile to swap as potentially problematic?_

 

With the symbiotic/complimentary relationship of elements in this design, it's sometimes hard to pin down problems to specific component(s). A build error, short or bad/out-of-spec part can cause trouble elsewhere.

 E.g. when I fried OB TO92s probing around tried limiting my replacements to what I thought could be bad. Was wrong & got to watch them fry again.

 That's why I suggested wholesale replacement of sand in suspect circuits. Assuming the L+R tube servos are ok. Just a thought.

 Me & my Proto PCB were getting tired of removing/replacing things so just went all out. Of course, it's worked perfectly ever since.


----------



## MrSlim

Tacitapproval, If you don't have one already, get yourself one of these: Desoldering Tool Professional Solder Sucker Pump TSL017 - eBay (item 400045454976 end time May-24-09 05:12:13 PDT)
 I've been in the tech field a long time, back in the day when we were fixing REAL computers in the field and we needed to be really good at desoldering components. Damaging a board was not an option. Using a desoldering pump like this will help reduce the damage done to the board through repeated component replacements. When I built my prototype, I put all (Yes all...) of the tombstone'd diodes in backwards. I was able to flip most of them around, and replaced a couple of other components (the 2595 didn't approve...) and its been singing nicely for me since without a problem. 

 I tend to agree with CF about replacing all the transistors in the right buffer.. They are cheap anyway. 

 I still think the DC swing has got to be coming from the buffer. C4 should block any DC coming from the input stage, and since it's only happening on one channel, I can't see how one of the common circuits(power supply, splitter) could be causing it. Of course everyone is entitled to MY opinion 
	

	
	
		
		

		
		
	


	




 , but Runeight was the one who designed this beauty, along with CF, so they would have the best one's to help diagnose your issues..


----------



## tacitapproval

I have replaced transistors in the right side buffer and TL082. This leaves D2R, which measures okay, in the right buffer, right? I have transistors, so I can swap them in the left buffer(worthwhile?), e12, and splitter. I don't have the diodes. Perhaps Bill will be willing to send them? Anything else?

 Cf -- How do I know the tube servos are correct?


----------



## holland

@tacitapproval. I'm not sure if my problem is gone or not. It has disappeared the last I checked, but I do not know why. The problem was happening, I put a socket saver on thinking it was heat on Q9R, Q6R, and Q7R that causes the problem as it builds up over time, and the problem went away. Removing the socket saver, to try and analyze further, and it didn't reproduce.

 I had replaced all the transistors in my right side buffer a while back.

 As for your question, the tube servos. Monitor the DC plate and cathode voltage of the tube pins. For the right side, the pin 6 and pin 8. Mine are fairly steady. The cap should be blocking the DC going through, anyway. The only thing that gets through would be AC. I would be surprised if it's the opamp on the tube, but it wouldn't hurt to test.

 Edit: I haven't looked at the amp for a few days, after the problem disappeared. I will try again when I finish the casework.


----------



## cfcubed

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_< snip >
 I tend to agree with CF about replacing all the transistors in the right buffer.. They are cheap anyway. 

 I still think the DC swing has got to be coming from the buffer. C4 should block any DC coming from the input stage, and since it's only happening on one channel,< snip >_

 

Actually, I suggested *all* TO92s in OB & splitter & e12. I even did CRDs in OB & had OPAs to swap in. 
 Radical for sure, but as a rifle wasn't working I reached for the shotgun
	

	
	
		
		

		
		
	


	




_*Cf -- How do I know the tube servos are correct?*_ - Think measurements you had for runeight could prove this *but think removing C4s * would really isolate DC offset to the OB (as MrSlim suggests, *Edit: pulling the tube may achieve same iso as pulling C4s*). Whenever I'd offset issues during prototyping I _think_ it was always the settling down of the buffer (temp-wise, etc) that caused them. I may have presented OB w/1M to ground in place of C4s, to give them an input ref, but don't remember.
 Runeight knows best here tho.


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Whenever I'd offset issues during prototyping I think it was always the settling down of the buffer (temp-wise, etc) that caused them._

 

When I was hunting my offset issue, I blew on the buffers and tripped the e12 immediately. I put a fan on it to see if things varied and it settled down, removing the fan and the DC started to move in a large fashion. That's what lead me to believe it's the temperatures and knowing BJTs increase current as temp increases.

 I honestly don't know what happened now, but the ambient temperatures are wildly different than when I initially had the problem (read cold now with temps in the 60s and 70s instead of 80s). Since I don't want to pull out a heater, I'll wait for warmer days.

 @tacitapproval, if you've got a socket saver, give that a try. I'm at a bit of a loss right now, as to explain what happened for me.


----------



## TimJo

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_I brought mine up and with a bit of luck on my side lately my CTH came to life without any issues._

 

 Quote:


  Originally Posted by *Coreyk78* /img/forum/go_quote.gif 
_Fixed mine. Switched the caps around and its working beautifully now 
	

	
	
		
		

		
		
	


	




 thanks guys!_

 

Congratulations guys. Now the fun starts! 
	

	
	
		
		

		
		
	


	




 @Adumus - let us know how your amp is doing after you swap caps...

 I'm just loving my amp. Meanwhile I'm saving my pennies to build a Bijou next.


----------



## sachu

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_haha, it's quite easy to make that mistake, I almost did it too -- perhaps need to make one of the caps Nichicon 
	

	
	
		
		

		
		
	


	





 nope, sorry didn't mean to leave that impression. I wanted to say was i first need to build a true A/B device that allows to switch amps 'on-the-fly' easily before I can subjectively hear their differences. My initial impression though is that the CTH and SS millett do not sound alike to my ears. The SS has warm, tubey like sound and much deeper bass while the CTH sounds more detailed, accurate and good channel separation with very sharp mids/highs (but not bright).. am very happy with it. 

 I'm currently using a Russian 61NP NOS tube which I'm going to let burnin for a bit.


 ._

 


 your observations are quite inline with mine..i did have the presonus central station acting as the DAC as well as an A/B box..

 The bass in the CTH got better with different tubes, worse with others. I have an amperex 6DJ8 that I want to try and also have a Seimens ECC92 coming in..so we'll see how those two perform.


----------



## wiatrob

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Hey Bill, I wanted to let you know my package arrived this week, and I installed the perf top on my proto.. It looks great and runs much cooler too..._

 

Great to hear - BTW - I installed a perf top on my proto and it still runs on the warm side... it does have a frankensteined 24V reg, should get in there and put a good one in at some point, and double check the sink.


----------



## wiatrob

The idea of tolerance/heat issues in the OB is interesting, since we're in a complex system here - wonder how that relates to slightly different tolerances in the splitter circuit.

 Temporary heatsinks (alligator clips?) on to-92s in the OB? If they got replaced, it seems maybe that it's something upstream , perf CFCubed's experience replacing lots of things (although odd as the splitter feeds both buffers).

 It's my understanding that Runeight has been swamped lately, I'm sure he'll weigh in soon.


----------



## tacitapproval

I was trying to check out the tube servo. I am not sure if I am understanding this, but on pin 6, I was getting @78vdc whith spikes up to 108v, triggering the e12. This must be it, right? This would point to a input issue, not the buffer. D1R? I did earlier swap out ICR. Something else I am missing?


----------



## runeight

Gentlemen, my sincerest apologies for being awol. There are many nice things about a consulting practice, but when the chips are down the customer gets the first call . . .

 Reading through I think that the only unsolved problem is tacitapproval? Is this right?

 If so, tacit, that pin 6 voltage spike would definitely trigger the e12 since the spike will pass right to the buffer. It's hard to say exactly what the problem is, but it could either be a bad D1R or it could be an intermittent connection. 

 You might try very carefully inspecting around the tube servo for the right channel. Even flexing the board a bit to see what happens. If you can't trigger it this way, check out the opamp socket and opamp fit. If the opamp flakes out or loses even one active pin the spike will happen.

 If you don't get anywhere with these steps then replace D1R. But my sense is that if it were bad it would just be bad. Unless it is cracked or something. But electrically it would either work or not.

 Hopefully getting the tube stable will fix your output problems.

 Let us know.

 Is there anythine else pending? Thanks to everyone for holding down the fort while I've been gone.


----------



## rds

runeight - 

 I was wondering if we can adjust the led current from the e12 to light the tube better. Something like 10-15mA


----------



## runeight

There have been several comments about BJT temps and its effects.

 BJTs are quite sensitive to temperature and have a positive coefficient, meaning that the hotter they get the more they conduct. Mosfets have a negative coefficient meaning that the hotter they get the less they conduct. This is why many designers prefer mosfets for O/P devices because they won't thermally run away.

 Any BJT complementary buffer is subject to temp issues. If one side of the pair is heated or cooled the offset will stray to one side or the other. This effect will be pretty fast. 

 You don't notice this on many amps because there is no offset protection circuit. The DC offset slops around but nothing happens to tell you this. So you go merrily along thinking that there is nothing going on but audio.

 Having an e12 tends to make it look like there is a problem here when, in fact, the amp is doing what most other amps with similar O/P stages are doing. 

 However, what happens to the DC offset also depends on the exact circuit used. For example, in a design like the PPA where the gain stage is an opamp and the discrete buffer is in the opamp feedback loop, the opamp will zero the DC offset quickly and there will be no drift.

 The extra challenge here is the hybrid design where the buffer must self zero and, therefore, must have a longer zeroing time constant so that the buffer opamp does not respond to low freq audio.

 In this case the buffer is subject to being rattled by input spikes and fast changes in the O/P devices. It will eventually pull back to low offset. The e12 is set to accomodate slightly large swings before triggering to handle this design. And, I'm pretty sure that when the design is working right (correct components, nothing intermittent, no spikes coming in from the source) you won't have e12 trips.

 I have designed an amp where the tube is not capacitor coupled and is in the DC feedback loop of the amp. It's the EHHA for those of you who would like to try an embedded hybrid that is totally DC coupled.


----------



## runeight

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_runeight - 

 I was wondering if we can adjust the led current from the e12 to light the tube better. Something like 10-15mA_

 

rds, the LED resistors are 2k and are essentially strapped across 20V. So they should be passing about 10mA now. But you can definitely burn more current. Try 680R to get about 15mA. 510R to get 20mA. I don't think the LV supply will notice this change and the e12 control transistors should be ok.


----------



## runeight

Correction. Bad math.

 Try 1k3 for 15mA and 1k for 20mA. Sheesh.


----------



## rds

cool, thanks runeight - I'll give that a try.


----------



## holland

@tacitapproval.

 108v? Like runeight said, either it works or it doesn't. It could be an intermittent connection, but also I'm wondering if it's a PS thing. If you can, reflow that section. But after that, and examining for cracks and flexing the board, check your B+. Does it spike at the same time?


----------



## tacitapproval

Ok, I reflowed all the joints on the right side of the input section. I am now getting TB+ 108V, pin 1 78v, pin 6 34v? Shouldn't this be 78v as well? The good news is it seems to be stable and music is playing through both channels. That pin 6 reading is confusing me.

 edit -- I swapped to another tube and now getting 78v. But why would that other tube (12bh7) sound fine at 34v on pin 6, let alone why was it reading that?

 edit -- Now it is at 46v and e12 trips are back. Something is obviously still wrong. As usual, I'm confused.

 Holland - B+ seems to be 108v consistently. It moves around from 107.5-108.2, or so, but doesn't seem to spike when the e12 trips.

 Also, I measured D1R against D2L, and they seem to be about the same.


----------



## sachu

yep.it should be reading 78Volts..looks like you might have a problem with your Q3P...


----------



## sachu

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_I have designed an amp where the tube is not capacitor coupled and is in the DC feedback loop of the amp. It's the EHHA for those of you who would like to try an embedded hybrid that is totally DC coupled._

 

God is it a beautiful design...absolutely love it..just the heater circuit left to finish up on mine


----------



## holland

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Also, I measured D1R against D2L, and they seem to be about the same._

 

I don't understand this. Do you mean D1L? What do you mean by measured against?

 You measured B+ via TB+? What about on the other side of D1R? What are the voltage drops across D1L and D1R with your various tubes?

 This tube you are having problems with? Is it the same one that has always given you problems? A 12BH7 is it? A different 12BH7 works? Am I understanding your problem correctly?


----------



## tacitapproval

Whoops, yes I mean D1L. I meant that I was getting similar readings between them on the diode setting of my dmm. Under power, I am getting 78v out of D1L and D1R. It is not one tube that I am having problems with, I have tried several different varieties. 

 Ok, now I am getting a steady 78v out of pin 6. This is confounding. Hopefully, it was just a bad joint and my various reflows got it. Of course, I have thought it was stable before.


----------



## holland

reflow it again, for good luck. 
	

	
	
		
		

		
		
	


	




 Look at the joint from the top. There should be some solder coming through the joint and holding.

 As sachu said, there is a transistor between TB+ and D1R. That is Q3P. When you measure the low voltage on pin 6, measure the other side of D1R and TB+. It could be a cold joint on Q3P as well.


----------



## tacitapproval

I have reflowed Q3P, but I am still getting pin 6 number that are all over the place. When I measure between the anode of D1R and TB+ I get @2.5V. Bill sent me some transistors, but since I was looking in the buffer before, I didn't ask for Q3P. Anybody have an extra they would be willing to send?


----------



## sachu

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I have reflowed Q3P, but I am still getting pin 6 number that are all over the place. When I measure between the anode of D1R and TB+ I get @2.5V. Bill sent me some transistors, but since I was looking in the buffer before, I didn't ask for Q3P. Anybody have an extra they would be willing to send?_

 

I am pretty sure I have a couple I can spare..let me check my inventory quick..

 edit: _Nope..looks like I have just enough for the upcoming build._


----------



## holland

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_When I measure between the anode of D1R and TB+ I get @2.5V._

 

This seems fine to me. The capacitance multiplier will drop voltage when loaded. The output voltage is 0.65v lower than the base voltage, which in turn is lower than the source voltage. A 2.5V drop with a 2mA current seems about right to me.

 Voltage is steady and not fluctuating? Fluctuating voltage may mean a varying current load. The CRD should be regulating the current flow at that point.

 The opamp is supposed to flow or pull current away from the cathode resistor to regulate the voltage at the plate.

 I would probably look at replacing the CRD, if everything else looks good to you.

 C1R is installed in the proper direction? What voltages do you measure at the cathode of the tube (pin 8 for the right side)?


----------



## tacitapproval

I think it has to be D1R. I measure 105v on the anode of it, but only 38v on the cathode. I also have witnessed the same fluctuations on it that I see at pin 6(I guess this would not be suprising), but the B+ and anode seem to be stable. Do others concur?

 Polarity of C1R is correct and Pin 8 was at 1.3v.

 Wiatrob-- Any chance I can trouble you again for a 1N5305 and MPSA42, so I don't have to put in a mouser order just for those?


----------



## Forte

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I think it has to be D1R. I measure 105v on the anode of it, but only 38v on the cathode. I also have witnessed the same fluctuations on it that I see at pin 6(I guess this would not be suprising), but the B+ and anode seem to be stable. Do others concur?

 Polarity of C1R is correct and Pin 8 was at 1.3v.

 Wiatrob-- Any chance I can trouble you again for a 1N5305 and MPSA42, so I don't have to put in a mouser order just for those?_

 

It is probably Q3P (MPSA42) that is causing the low reading on Pin 6 and D1R, I had a similar problem with low voltage(55v) on Pin 1 and D1L, replacing Q4P fixed it.


----------



## danobeavis

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_I like clean and simple, and Beavis' box is certainly that, but I have to warn everyone about a change you will have to make to the build instructions to use it with the CTH (and any other amp that uses a VIRTUAL GROUND(in the CTH it floats at about +12V) on the output). His wireing instructions suggest that you connect all the grounds together. That would be a no-no, since you would be connecting real ground and +12 V together. 
 You should only connect the input ground to Buss A and Buss B Send, and connect the Output Ground to Buss A and B Receive. I'll email him about his also, so he changes his site.._

 

Email received, thanks much for pointing out the issue, and suggesting a fix!

 Site updated!


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I think it has to be D1R. I measure 105v on the anode of it, but only 38v on the cathode. I also have witnessed the same fluctuations on it that I see at pin 6(I guess this would not be suprising), but the B+ and anode seem to be stable. Do others concur?

 Polarity of C1R is correct and Pin 8 was at 1.3v.

 Wiatrob-- Any chance I can trouble you again for a 1N5305 and MPSA42, so I don't have to put in a mouser order just for those?_

 

You could 
	

	
	
		
		

		
			





 I'll send you an email.


----------



## zkool448

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_I like clean and simple, and Beavis' box is certainly that, but I have to warn everyone about a change you will have to make to the build instructions to use it with the CTH (and any other amp that uses a VIRTUAL GROUND(in the CTH it floats at about +12V) on the output). His wireing instructions suggest that you connect all the grounds together. That would be a no-no, since you would be connecting real ground and +12 V together. 
 You should only connect the input ground to Buss A and Buss B Send, and connect the Output Ground to Buss A and B Receive. I'll email him about his also, so he changes his site.._

 

 Quote:


  Originally Posted by *danobeavis* /img/forum/go_quote.gif 
_Email received, thanks much for pointing out the issue, and suggesting a fix!

 Site updated!_

 

MrSlim and danobeavis, just love it when communication works. Another perfect example when members share ideas and comments, things always end up as well as they do. Thanks to you both. 
	

	
	
		
		

		
		
	


	




 In terms of the A/B box, listening to differences in SQ, nuances, etc. between amps is my primary reason for wanting one but also for one other purpose. It may also become permanently connected to my source since there are many times I'm undecided which amp or tubes I feel like listening to at that moment, … perhaps I’m just way lazy to swap cables or amps/tubes sometimes


----------



## zkool448

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_All- I'm out of town for a week so if anyone needs spares it'll take a bit of time. The first set of custom panels showed up in The mail minutes before I left. Thy look great. 

 I'll get some pics posted when I return. Good luck with your builds..._

 

Hi Bill, just wondering if you had a chance to post some pics of the custom panels. Hoping to see a sneak peek of what they look like. I'm currently modeling the casework (still undecided on the design) so I'm curious if I might/should rough them in. Thanks!


----------



## holland

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_It is probably Q3P (MPSA42) that is causing the low reading on Pin 6 and D1R, I had a similar problem with low voltage(55v) on Pin 1 and D1L, replacing Q4P fixed it._

 

It would be fairly easy to test, though with a steady voltage drop across it, I'm not sure.

 Anyhow, with the amp turned off, set your DMM to diode test. Put the red probe on the base (middle pin). Put the black probe on each other leg (collector and emitter). It should measure about 0.6V for both. Reversing the probes should yield nothing.

 An NPN can be viewed as two diodes, back to back, for this test. With the anode at the base and the cathodes at C and E.

 If it passes, the transistor is good.

 You can do a similar test for the CRD, i.e., one way only.


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_You can do a similar test for the CRD, i.e., one way only._

 

One thing tho that concerns me about out-of-circuit testing for the more complex parts is I'm not sure it's _really_ testing it (e.g.performance under load & temp conditions.)
 CRDs for example are more complex creatures than std diodes. 
 Again, piecemeal replacements may hit the problem but it requires some patience (& luck) IMO.

 P.S. Boy, wiatrob is sure going above & beyond in his support of the kits - Good man.


----------



## tacitapproval

Thanks for everyone's patience with my flailing attempts to troubleshoot this problem. I have yet another hypothesis about the source of the trouble. I think Alex is right, there is something physically dodgy going on. If I push up and down with the probe while reading pin 6, it seems I can get the voltage to change. I have gone over the joints on the right side input yet again. This hasn't solved it. Maybe there is damage to the board? Ughhh...

 Q3P tests out ok, by the way.


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_CRDs for example are more complex creatures than std diodes._

 

True, but if you can test a transistor you can test a CRD. A CRD, can be modeled as a JFET with gate and source shorted. The quick test is to make sure the diode is still functional. If it's shorted out or broken completely, it won't function as the basic junction is gone/toast. Any of the testing won't show in circuit failures, best would be to pull the end of the CRD and put an ammeter in series to measure the current flow. That's a bit of work, and might as well just pull the part completely instead of testing that.

 I would rather try and test some parts in circuit instead of blindly replacing parts. Brute force works, but it doesn't help the knowledge base in the long run.


----------



## holland

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Thanks for everyone's patience with my flailing attempts to troubleshoot this problem. I have yet another hypothesis about the source of the trouble. I think Alex is right, there is something physically dodgy going on. If I push up and down with the probe while reading pin 6, it seems I can get the voltage to change. I have gone over the joints on the right side input yet again. This hasn't solved it. Maybe there is damage to the board? Ughhh...

 Q3P tests out ok, by the way._

 

Got a loupe? Examine the traces and joints. It's possible, sometimes it happens, that there can be an errant trace from the fab house, or bits left over shorting something...or a small wire floating around when you wired it that makes contact somewhere.

 When you say push up and down, you mean with the probe contacted in both cases and just applying pressure? Or are you breaking contact and making contact? There can be some flux with contact make and break, especially repeatedly. I use a small clip (mini hook clips), to clip onto the leg of the socket, which connects to my DMM. With that in place, flex the board around the area you suspect. Push down on the tube, and release, for example.

http://www.tequipment.net/FlukeTL940.html

 Edit: You may want to reflow the tube socket as well, it could be a bad joint around that area. The loupe will show it though, I use a min 10x, sometimes 20x.


----------



## tacitapproval

Yes, I mean applying more or less pressure on the board while maintaining contact. I have reflowed the socket, as well as anything that looked like it could be at all suspect. I don't have a loupe, but I do have a magnifying glass. I will look it over carefully. I also have some alligator clips, so I can try that.


----------



## adamus

fired my amp up..... all checks out..... except there is no heat. 

 The heater voltage is climbs to 1.2v, then drops back to 1. 

 Everything looks ok, except L1H reads very very high resistance (1m +)

 IS that my problem, or is the switcher unhappy?


----------



## cms5423

. EDIT: Posted this question in it's own topic under the DIY forum.


----------



## cfcubed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_fired my amp up..... all checks out..... except there is no heat. 

 The heater voltage is climbs to 1.2v, then drops back to 1. 

 Everything looks ok, except L1H reads very very high resistance (1m +)

 IS that my problem, or is the switcher unhappy?_

 

Those coils should have VERY low resistance value... Don't know exactly, but thinking < 1 ohm (? see their datasheets?).

 The switching heater is actually a pretty low-count circuit. You may see it in the lower-right of the PS schematic. We've not had a problem with it yet to my knowledge...

 I'd inspect the heater components installed & their polarity carefully. 
 Then I'd pull the L1H (3.3uH one) & check voltage from its "input" lead to ground. It should measure about 12.6 or 6.3 VDC depending on the heater switch.
 If the voltage there is not close, then you've a problem before L1H. It it is close then you've a problem after L1H (possibly a short).

 Note: If you find it is only L1H or C1H are bad, the CTH should function with L1H position shorted (but will not have ripple filtering). *But do not do this, or pop in a new L1H, until you assure that from L1H "output" lead to tube is not shorted to ground.* 
 The "output" lead of L1H goes to (#4 or #5 of) tube socket & the other tube socket heater pin is ground (#4 or #5).

 Edit: ALL part numbers are as components are shown in the schematic I referenced.


----------



## adamus

sorted it, the tiny little copper wire wasnt attached to the lead, a quick tack of solder and i have 12.6v.


----------



## cfcubed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_sorted it, the tiny little copper wire wasnt attached to the lead, a quick tack of solder and i have 12.6v._

 

Heh, the obvious thing
	

	
	
		
		

		
			





 I was thinking its high resistance was from an open somewhere on the coil. Nice that is was an easy fix. It is a bit sensitive.

 So, later let us know how she sounds... AFAIR you've built & heard a few amps


----------



## holland

awesome, adamus. BTW, do you still have your SOHA II that you built for someone? I was wondering if you could do a quick comparison. The main differences I notice, is the bass. The SOHA II just has that much more kick to it, even with similar tubes, though, I've got mine biased at 10mA tail current now.


----------



## adamus

afraid not, it went a while ago. i only have the bijou left at the moment. 

 just fired it up again, heaters are now working, but there is a bad 100hz hum. does connecting the SG make much difference (its just on the bench at the moment)?


----------



## holland

Maybe, if it's related to external stimulii. If it's not, no, but it could be other things too. What if you move the wires around and/or physically relocate the amp? I don't hear hum on mine, but I do use a 100-120ohm output resistor.


----------



## sachu

I am having some hum when I touch the volume knob on mine. It goes dead silent when I don't touch the knob. 

 Am thinking it is something to do with my wiring (cold solder joint) rather than a ground loop problem, since it wasn't present with the previous (BOM) pot.

 Any ideas?


----------



## adamus

hmm, pin 1 to sg reads 101v, something isnt right. that should be 80v?


----------



## holland

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I am having some hum when I touch the volume knob on mine. It goes dead silent when I don't touch the knob. 

 Am thinking it is something to do with my wiring (cold solder joint) rather than a ground loop problem, since it wasn't present with the previous (BOM) pot.

 Any ideas?_

 

Ground the pot shaft. If you are using Alps blue, I unscrew 1 screw in the back, and wrap a thin wire around it and screw it back in. Run the wire to SG.

 If that's not possible, you could use a large ring terminal, put it around the pot shaft on the inside and wire it to SG.

 That only applies if the chassis is not grounded thoroughly (scraping off the coatings where ever the metal plates meet).


----------



## holland

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_hmm, pin 1 to sg reads 101v, something isnt right. that should be 80v?_

 

It should be ~80V, correct. Most of us read around 78V, IIRC.

 Check your CRD.


----------



## sachu

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_hmm, pin 1 to sg reads 101v, something isnt right. that should be 80v?_

 

with the tube it should read 80V, but without tube 101 sounds about right.

  Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Ground the pot shaft. If you are using Alps blue, I unscrew 1 screw in the back, and wrap a thin wire around it and screw it back in. Run the wire to SG.

 If that's not possible, you could use a large ring terminal, put it around the pot shaft on the inside and wire it to SG.

 That only applies if the chassis is not grounded thoroughly (scraping off the coatings where ever the metal plates meet)._

 

yes its the ALps blue..Will give it a try..I did that on the Ck2III, but I had other problems with that one which only went away after I put in a ground loop breaker.


----------



## adamus

thats with tube in, checked out all the values for the input components (left), they all check out fine, the CRD measures ok too.... maybe te opamp is toast?


----------



## holland

What's the differential across the CRD? 101 is awfully close to having no current flowing through that triode. I'm not sure if it could be the opamp. What happens if you remove the opamp?

 Edit: Do you have any voltage at the cathode for the left side?


----------



## adamus

about 30v across the good side, and about 8v across the 'bad side'


----------



## rds

hey guys,
 I'm looking for a toggle switch with a cover to use for the heater switch. I'm sure I've seen them at digikey before - they usually have a red cover that you have to flip up before you can access the switch.


----------



## holland

hmm, and the cathode? it could be the opamp. what are the opamp pin readings for +, -, output, and opamp power voltages?

 If you pull the opamp completely, what happens? That should, I think, remove the opamp sensing circuit entirely as no current should flow through that side. That should leave a basic grounded cathode configuration with a CCS plate load. I think, not 100% sure.


----------



## adamus

24v and 0v, that looks right to me on the opamp power rails rails. in + / - about 2.3 and 2.9v

 cathodes are 2.9 on the bad side, 2.4 on the good.


----------



## tacitapproval

I am cautiously optimistic that I have at least improved the situation. I pulled one of those shielding wires that had hidden in the socket for ICR. So far, no voltage fluctuations and no e12 trips. I think this would make sense with the problems I have reported. I did get a brief noise (something like a needle being dragged across an LP), which I have heard momentarily before, that makes me think I may still be dealing with these fine wire hiccups elsewhere. I guess more poking and prodding, but it looks a lot better. The density of the parts on the board really makes it difficult to get into all the little spaces these things could go.

 Adamus -- best of luck with tracking down your issue.


----------



## adamus

shouldnt be too bad, its on the input stage, and its ac coupled so it wont harm anything downstream..... just not sure why its pulling naff all current.

 its not the opamp itself, i just swapped them round (ICL and ICR). Same result. 

 It must be something daft like a wrong component. I'll sleep on it and take a look with fresh eyes


----------



## holland

Good to know. Removing the opamp should have proved/disproved the same thing. Do you have another tube to try? The problem is likely the CRD, at this point, assuming the tube is good and everything is wired correctly. Removing the opamp should also let the tube itself set the operating points, with the CCS plate load.

 Are the voltages on the anode of the CRDs (left and right) at the same level? I would guess your left would be higher, since the current load seems to be smaller.


----------



## rds

I thought these might be helpful for people building the Spruce Canyon Labs kit. I think the kit follows the recommended bom exactly so this should be helpful for any builders looking for some reference board pictures ( board images ).
 Note that the resistor values can be read from the top image, except for those that are tombstoned.



























 ** pcb image pcb picture


----------



## sachu

nice!..looks great..when are you firing it up? what kind of case are you using?


----------



## holland

looking good, rds. It looks like power up is coming very soon.


----------



## Forte

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I thought these might be helpful for people building the Spruce Canyon Labs kit. I think the kit follows the recommended bom exactly so this should be helpful for any builders looking for some reference board pictures ( board images )._

 

Neat build and great photos. What caps are you going to use for C4L/R?


----------



## wiatrob

Not liking my heater toggles? 'twas all mouser had in stock at the time. I found safety switch cover's at Digikey, but not arming-type toggles. Most of the ones I've seen are large,

 FWIW, I've never knocked the heater toggle by accident...


 Nice pics BTW...


  Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_hey guys,
 I'm looking for a toggle switch with a cover to use for the heater switch. I'm sure I've seen them at digikey before - they usually have a red cover that you have to flip up before you can access the switch._


----------



## wiatrob

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I thought these might be helpful for people building the Spruce Canyon Labs kit. I think the kit follows the recommended bom exactly_

 

The kits follow the BoM very closely. Except when something isn't in stock (heater slide switch). Some kits sold with wall warts shipped with 2.1mm sockets to match the attached wall wart cords.

 All cap/resistor/actives are per BoM spec, pretty much to the part number.


----------



## MrSlim

Adamus, What tube are you using? I was having a similar problem where the Plate voltage were high and it was because I tried using a 12AX7 which is outside the operating 
 params of the CTH. Once I put in a 12BH7A, they were fine


----------



## MrSlim

Sachu, still taking a break from your Thesis?


----------



## adamus

mr slim, I am using an 8416, which worked fine a soha II, and i have two and both behave identically. I can try a 6n1p but its consuming so little current on that triode, i guess something is wrong.


----------



## olblueyez

12au7/A variants
 ecc82
 6680
 6189
 5963
 7316
 5814
 6922
 6dj8
 8614 (12.6V 6922)
 6n1p
 6N23
 12bh7/12bh7A
 6BQ7

 The heater supply will accommodate 12.6V and 6.3V tubes running anywhere from 150mA to 600mA. 

 The front end servo will accommodate many types of tubes. Its design center is around the 12au7 type.

Amp Features


----------



## smeggy

My CTH has arrived from sachu, just gotta wire up the various connectors and switches, house it and we're good to go


----------



## rds

Thanks guys.

 I'll be using the small Hammond case with the pref top from Spruce Canyon Labs. I wanted to put a 1/4" on the front and mini jack on the back but it looks like with the fuse, power switch and heater switch on the back there won't be room... still I might give it a shot.

 I'll be using Sonicap Gen II for the coupling caps.

 Wiatrob, I don't have a problem with your heater switch except that I hate cutting square holes. But I think I can get away with a round hole and still have it look good. You're right about the arming-type toggles - they would be too large.

 I'll wait till I have the Sonicaps and the case work done before I power this up.


----------



## adamus

I tried the 6n1p, and same result. This is looking like the CRD is the problem.

 anyone got a spare? I cant source them in the uk.


----------



## smeggy

I have a quick question for all you CTH geniuses. 

 I have a spare switched pot from an AMB mini3 and was wondering if I could use that as the main power switch as well as pot. It seems a more elegant solution to using a separate switch for power.


----------



## MisterX

Other then being a major PITA to wire it should be OK (the switch in those pots is rated for 16 volts DC @ 3 amps).


----------



## smeggy

why pain in the ass? I take it it's the two connectors at the back.


----------



## olblueyez

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_why pain in the ass? I take it it's the two connectors at the back._

 

Sounds like a good idea, maybe built in to REV.2 so no wiring is necessary?


----------



## holland

You have to run one of the AC lines to the front. It won't be horrible. The only thing I don't like about those pots are the tapers. However, you can drill out the studs, separate the pot, and put in a 15A taper pot onto the front, with the switch in the back.

 Or you can use a pot extender, depending on how you are wiring it and if you're going with a larger case. I never could properly align those extenders though.


----------



## cfcubed

@rds - Your pics look great - perhaps Bill could use them on the site somewhere for builders to compare to prior to pwrup... Your C5P & C10P look tall sure it will slide into small case? *Edit: I could be wrong, my builds are older when we had shorter/fatter C5P & C10P]*. 
 And my what patience you have waiting for C4s
	

	
	
		
		

		
		
	


	




 @adamus - I've no CRD spares, even pulled them from the P2P proto, else I'd fire one over.

 @smeggy - I used that very pot in my 1st build & while taper is not ideal, it worked fine. Did replace it later w/BoM pot (as part of larger order).
_Someone_ here did use that pot & wired its switch as on/off in CTH, forget who, but if you do this you are running A/C wires right across the board. And you'd be bringing A/C to *very* close proximity to low-level input within the pot. Wouldn't be surprised if you got some hum doing it.


----------



## MrSlim

I used the larger hammond case, but still kept the input/output at the front with the pot, and let the AC live at the back.. Simple is better .. the more AC running around, the more noise you are going to get.. Keep the power switch at the back..


----------



## holland

I agree that bringing AC up front may cause noise issues due to the proximity. Though, my stance is different. Try it and find out. Don't build a case around it until you do. All my builds, for instance, run signal lines back to front, and I have no noise. As noted, others think it's not great, but it's my build. 
	

	
	
		
		

		
		
	


	




 Basically, try it and decide for yourself. Personally, I wouldn't do it on this amp, but that means nothing for anyone else. It may help others, should you find that it has no noise. One can even run a separate switch on the front, like full-sized amps. I don't think that'll cause problems, though I still wouldn't do it for other reasons.


----------



## adamus

hmm. with no opamp the voltage voltage drops to 86v, which is nearer the mark for current draw......


----------



## holland

check the resistor values around the tube cathode servo and the cathode resistor (cathode resistor is probably correct)....R3, R4, R5, R6, R7, and R8. Opamp orientation?

 I'm not sure how voltage is going *up* or might be possible if the operating point is completely different than what it should be. The servo sets up a voltage divider for the rail (the 2.3V you measured), feeds that into the positive leg as reference and uses a single ended non-inverting amp configuration to adjust the negative leg (which is the plate voltage with a divider).

 What should be happening is that your default 86v will measure as ~2.6v (can check at the junction of R5 or R6. should drive down to the reference of ~2.3V.

 Without the opamp in, measure the voltage at the cathode resistor, for reference.


----------



## adamus

unless my eyes decieve me, the resistors all are correct. opamp is correct. cathode resitor is ok. 

 this has me slightly stumped....


----------



## holland

what is the voltage @ the cathode resistor without the opamp in place?


----------



## adamus

cathdode, pin 3 = 2.73v, anode at 86v, no opamp. at opamp socket, V+ = 24v, V- = 0v. -

 opamp back in and 101v on the anode, pin 1.


----------



## tacitapproval

My CTH has now been stable for over 24 hours with every tube I have thrown at it. I am happy to have finally worked through my self-inflicted kinks. Thanks to everyone for the help.


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_My CTH has now been stable for over 24 hours with every tube I have thrown at it._

 







 Great to hear!


----------



## wiatrob

Zkool, I'll post some panel pictures over on the announcement thread tomorrow. I accidentally put 24VDC on the first batch instead of 24VAC. Duh - corrected in the next batch. But you'll get the idea.


----------



## wiatrob

Hazards of buying 'lots' of tubes: I was restocking 12AU7's for the next round of kits, got a batch in today. Included in the box: Tung Sol JTL's, Sylvania 6189, USN CHS 5963, GE 5814WA - half go in to the personal box, time to look for more. 
	

	
	
		
		

		
		
	


	




 Even though I'm not tube-eloquent, the 6189 is fantastic sounding in this amp...


----------



## smeggy

Hi gang. 
 I wired up the CTH and I'm getting full sound from one channel but only a faint sound from the other. Any clues what to check?


----------



## adamus

anymore ideas on my 'pass no current with opamp' problem. this should be entirely fixable....


----------



## HeadphoneAddict

Blutarsky picked up wiatrob's CTH review sample the other day from me, and will be comparing it to his EC-01, Zana Deux and Melos SHA Gold over the next couple of weeks or so. I loaned him my Mullard short plate which I liked so much in it as well. He has about 8 or so tubes from Bill, and a sheet telling him what voltage to set the amp at, so it should be safe.

 We briefly compared the CTH to the EF1 and Amphora again, with the tube hybrids being very similar to each other as before. Then I unplugged the EF1 to move the power supply and forgot to plug it back in and power it up, so didn't have time to warm it up again. The CTH with Mullard short plate is a rich and full sounding hybrid with good power for low and high impedance phones. It was just a little less detailed, spacious and extended than the more costly ALO Amphora, which also retains a sense of tubey richness despite being a SS amp. I never did find a tube combo for the CTH that could exceed the Amphora, and it was fairly well matched by the EF1 with a Mullard tube as well (although it passed up the EF1 when EF1 had the stock RCA clear top).

 We also listened to the AV123 headphone Bluto acquired from Mark Schifter which sounded nice but I think I prefer the CTH a little bit more with the Grado HP-1000. There was nothing bad about the AV123 but I simply didn't have enough time with it to get a good impression for what it can do. That will come later, and I did come away with the impression that the Av123 headphone amp sounds good to me. It seemed like the CTH had better synergy with the HP-1000's (Equinox cable) and the AV123 was really good with the SARN re-cabled ATH-A900, although the CTH did a good job with the A900 too and visa versa.

 Again, I enjoyed my final visit with the CTH before it went to the next tester, only wishing for a power switch and a set of RCA input on the rear, if I was to be purchasing one. I think the CTH sounds much bigger than it's price or size, and due to the ease of finding tubes for the CTH it might be a better choice for some people than the Millett Starving Student, which I also really like a lot. And the price is more affordable than the similarly performing EF1 too, if you are capable of building it yourself (not me). I would not be surprised if Blutarsky found it to be good competition vs my old TTVJ portable Millett hybrid as well (which is a very amp too).


----------



## olblueyez

Must be why someone got dibs on my two short mullards I was selling.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Must be why someone got dibs on my two short mullards I was selling._

 

And my Siemens arrived today but I only have the EF1 to try it in now...


----------



## sachu

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_And my Siemens arrived today but I only have the EF1 to try it in now..._

 

and my Siemens ECC82 is on the way too..

 Its interesting to note that you found the Amphora better than the CTh. From what I remember..the CTH was a whole lot better than the Amphora..goes to show that it pays to listen to gear with your own ears, gear and music...


----------



## HeadphoneAddict

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_and my Siemens ECC82 is on the way too..

 Its interesting to note that you found the Amphora better than the CTh. From what I remember..the CTH was a whole lot better than the Amphora..goes to show that it pays to listen to gear with your own ears, gear and music..._

 

Yeah, but there was not "a whole lot better" of anything when comparing these amps, they are all good. I do have a few hundred hours on the Amphora to burn-in the Vcaps which take a long time to settle down.

 For completeness sake, I will add that this time around we used my Mac Mini > Airport Express > PS Audio Digital Link III > amps. Whereas the last time I reported my impressions of the CTH on the 16th I used my iMod with Vcaps as source to compare Amphora/CTH/EF1/Mustang. My first comparison included using RS-1, HD600, D2000, IE8 and K240M. This time we used re-cabled HP-1000 plus a pair of re-cabled and internally dampened ATH-A900.

 Here are my first impressions report: http://www.head-fi.org/forums/f6/ver...ml#post5614415


----------



## smeggy

Woohooo, after some troubleshooting with sachu, it's alive and well


----------



## sachu

me like extra glowy tunes..woohoo.. 
	

	
	
		
		

		
			





..now get to turning out a kickass case for that thing...


----------



## MisterX

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Woohooo, after some troubleshooting with sachu, it's alive and well 
	

	
	
		
		

		
		
	


	


_

 


 What's the verdict on wiring one of those pots like that? 
 PITA or not?


----------



## smeggy

Quote:


  Originally Posted by *MisterX* /img/forum/go_quote.gif 
_What's the verdict on wiring one of those pots like that? 
 PITA or not? 
	

	
	
		
		

		
		
	


	


_

 

Yeah, those tags are tiny and very close together. A bit of a squeeze but it works nicely 
	

	
	
		
		

		
		
	


	




 Aside from repairing the beta, the next project is a Cavali EHHA which is a bit more spacious. Fun fun fun


----------



## smeggy

I have a question for those more familiar with tube stuff, does anyone sell tube socket plugs with solder pins as well as sockets so I can make my own tube extender? I want to do something different with the housing (if I get time) and I'd need the tube off the board via wires. 

 Would I be better off just removing the existing socket and wiring directly to the board?


----------



## olblueyez

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I have a question for those more familiar with tube stuff, does anyone sell tube socket plugs with solder pins as well as sockets so I can make my own tube extender? I want to do something different with the housing (if I get time) and I'd need the tube off the board via wires. 

 Would I be better off just removing the existing socket and wiring directly to the board?_

 


 They make different kinds, if you want it up top you can get one that is surface mount with 2 screws and tabs below for your wiring. I think I have seen 3 or 4 types.

www.tubeworld.com Has what y our looking for.

http://shop.ebay.com/?_from=R40&_trk...All-Categories


----------



## cfcubed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_anymore ideas on my 'pass no current with opamp' problem. this should be entirely fixable...._

 

I'm sure runeight would have chimed in on this if he'd the time... I'll ping him anyway
	

	
	
		
		

		
		
	


	



 IIRC, one channel is working fine & one is not, so yes shouldn't be that bad to localize & fix. BUT must be *really* careful taking measurements, etc on a live CTH board. Easy to short something & see smoke.


----------



## zkool448

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I thought these might be helpful for people building the Spruce Canyon Labs kit. I think the kit follows the recommended bom exactly so this should be helpful for any builders looking for some reference board pictures.<snip>_

 

rds, very meticulously done especially looking at your tombstoned diodes, very cool!

  Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Woohooo, after some troubleshooting with sachu, it's alive and well 
	

	
	
		
		

		
		
	


	


_

 

Congrats smeggy! Can't wait to see the final product. Sure feels great to be in company of so many experts in here


----------



## holland

adamus, I'm not runeight, but I think your CRD is having trouble regulating. Since we know the starting point, and what should happen, and we know what happens when the opamp is in, I can only conclude that your CRD is having trouble regulating current.

 Can you humor me with 2 experiments?

 1) On the good side, pull the opamp and measure the plate voltage and cathode voltage, to use as a reference as to "what works". It should be fairly close to the bad side, with the opamp removed as dual triodes are (from what I understand) fairly close to each other normally.
 2) on the underside of the board, put a 3K resistor in parallel with the cathode resistor on the bad side, that should drop the effective resistance to 1K instead of 1.5K. This should flip the starting point and have the opamp source instead of sink current. What happens before the opamp is in place, and after as far as plate and cathode voltages go?

 I'm sure when Alex chimes in, it'll be more definitive.


----------



## TimJo

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_
 Even though I'm not tube-eloquent, the 6189 is fantastic sounding in this amp...
_

 

I like the 6189 as well. I have the RCA version, but I'm sure Sylvania built a good one as well.


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_adamus, I'm not runeight, but I think your CRD is having trouble regulating. < snip > I can only conclude that your CRD is having trouble regulating current.

 Can you humor me with 2 experiments?_

 

How bout a 3rd... Call it 1A) Having everything installed & switch CRDs L <-> R & see if the problem moves with it? Then maybe the opamp?

 Perhaps that's been suggested before, and I know its brute-force (holland
	

	
	
		
		

		
		
	


	




)... But if one side works & one side doesn't its an option. If not the brightest, most technically high-level one.


----------



## adamus

chaps, I am in discussion with alex on it, i'll wait for his views then try your experiments.

 thanks for the help on this holland and cfcubed - much appreicated


----------



## adamus

alex is pointing the finger at the CRD. apparantly the voltages are looking good around the omamp, the only thing lack is the crd regulation.


----------



## holland

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_How bout a 3rd... Call it 1A) Having everything installed & switch CRDs L <-> R & see if the problem moves with it? Then maybe the opamp?

 Perhaps that's been suggested before, and I know its brute-force (holland
	

	
	
		
		

		
		
	


	




)... But if one side works & one side doesn't its an option. If not the brightest, most technically high-level one._

 

Haha, sure. But, he's already swapped opamps from L & R, and the problem persisted. He's also closely checked the resistors and from the readings they are in the proper spots. The opamps are also properly oriented.

 Can definitely swap the CRD, but if you didn't install it with some lift, it's a PITA to get to. 
	

	
	
		
		

		
		
	


	




 Anyway, my bet is on the CRD having trouble regulating current when the opamp tries to sink current to drop the voltage. It just keeps dumping more, moving the cathode voltage up, moving the plate voltage higher. The opamp servo only works when the current is held constant.

 That's my edumacated guess.


----------



## adamus

I think i concur, but the result with no opamp makes me wonder

 Waitrob (thanks) is sending me a new CRD, so we will see if my issues are down to one part.


----------



## holland

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_alex is pointing the finger at the CRD. apparantly the voltages are looking good around the omamp, the only thing lack is the crd regulation._

 

Cool..

 I know for you, the CRD is hard to get. You can air wire a replacement until you get one from somebody. The replacement can be a simple ring of two BJT to source current...or if you have something like an LM317 you can wire in on a perfboard with ~625ohm resistor.


----------



## adamus

ok, all change. 

 pulling both opamps the results are almost identical. This effectively turns the input into a grounded cathode amp i think. it indicates both CRD's are doing the same thing. 

 from alex 

 "However, looking at your numbers, the opamp on the bad channel is trying to make the cathode more positive to turn off the tube. Yet it is detecting an anode voltage over 100V. What it should be doing is trying to decrease the cathode voltage to get more current to flow in the tube and to pull the anode voltage down. So the opamp is behaving exactly the opposite to what it should be doing. Have you tried replacing C2R?"

 cr2 swapped and no change.

 still debugging this one, it should be simple but something is miss behaving.

 looks like a servo issue. next thing is to replace the crd with a resistor (11k) determine if the servo is indeed dodgy.


----------



## holland

Can you pull one end of the CRD and put an ammeter on it? I'm somewhat doubtful it's the servo. It could also be possible that there's an issue with the board, a trace perhaps?

 You could also just swap the CRD from the good to the bad and see if the behavior changes.

 I stated my hypothesis in an earlier post, and I think that is what may be happening.

 One way to test is to change the starting parameters so that the servo pushes current, instead of sinking. That is to put the 3K resistor in parallel with the 1.5K cathode on the bad channel. That should bring the starting point down. You can even use a 2K resistor if you like. The opamp will have to source more current to bring the cathode voltage up, to bring the plate voltage up.

 The plate resistor would definitely pin it.


----------



## adamus

I'll try the resistor tomorrow and report back. thanks for the help.


----------



## adamus

I spent ten minutes ohming each side to check both are 100% the same. 

 Checked out fine. component values seem fine, this also allows me to rule out a bad trace or a short. 

 unfortunately this points the finger at a bad component, so tonight i will replace the crd with a resistor and go from there.


----------



## smeggy

Until I get more time, this $4.50 rat shack plastic box will have to do


----------



## MisterX

It actually looks pretty good in that case. 
	

	
	
		
		

		
		
	


	



 I could have swore I threw a nut and washer for the pot in the bag with the rest of the parts from that Mini3....


----------



## smeggy

Yeah, it's there somewhere but I just happened to grab the first nut that fit. Gotta get a little volume knob as well. As long a it works.. 
	

	
	
		
		

		
		
	


	




 Just hope the box doesn't melt.


----------



## sachu

dude!..you better hope that plastic is made of Bakelite or something..atleast make sure the regulator IC with the heatsink on it isn't touching the plastic..that IC gets to 70+ deg C on mine.


----------



## smeggy

Yeah, I chose that box as it has plenty of space around the board. There are 12 big holes in the bottom, bigger than the top ones so it's getting more ventilation than the metal cases and the amp/box doesn't get nearly as toasty as your did while I had it. The board is on nice long standoffs and the air can circulate very nicely.

 I don't forsee any problems with it at all. All working spiffily


----------



## wiatrob

Quote:


  Originally Posted by *MisterX* /img/forum/go_quote.gif 
_It actually looks pretty good in that case. 
	

	
	
		
		

		
		
	


	


_

 

Just take a Sharpie to those screw heads...
	

	
	
		
		

		
		
	


	




 BTW, how's it sound ?


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Until I get more time, this $4.50 rat shack plastic box will have to do_

 

I agree... It *does* have a simple, low-budget appealing look. 
 All it needs is a nice, small, cheap plastic push-on knob w/white indicator line.
 Being so specific because I've an extra that I _think_ fits the bill that I've no need for.... I could 1st class mail to you if you want. Just PM. *[Edit: Holland's idea below vvvvvv is better & cheaper than 1st class mail
	

	
	
		
		

		
		
	


	




]*


----------



## holland

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_unfortunately this points the finger at a bad component, so tonight i will replace the crd with a resistor and go from there._

 

Can you pull the anode of the CRD and put an ammeter in series? I'm curious to know what is going on. You don't have to of course, but I figure it's on the way.

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_All it needs is a nice, small, cheap plastic push-on knob w/white indicator line._

 

Ratshack has one that's, to be honest, not bad looking (to me). I hate to admit it, but I do use this on cheap builds, now and then. It's a screw on, single screw. Some heatshrink around the pot shaft, and this would fit fine.

Hexagonal Control Knob - RadioShack.com


----------



## adamus

how do crds work, in my simple mind it will limit the current is over 2ma, myvoltages suggest there is less than 2ma going through it..... bad science from me there!


----------



## adamus

volatge diagram attached if that helps


----------



## smeggy

Thanks guys.

 The thing sounds great. I really enjoyed my time with Sachus CTH and this one sounds just as good. I'm extremely impressed with these amps.

 I think the best thing about the plastic project box is that about 10 minutes with a step drill bit and all the casework is done


----------



## holland

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_how do crds work, in my simple mind it will limit the current is over 2ma, myvoltages suggest there is less than 2ma going through it..... bad science from me there!_

 

http://www.centralsemi.com/PDFs/sele...t_is_a_cld.pdf
http://www.centralsemi.com/PDFs/prod...N5283-5314.pdf


----------



## adamus

Ok, i just tried an 11k resistor in place of the CRD..... and no joy. 

 the servo must be doing the wrong thing. This suggests to me that the crd is ok.


----------



## runeight

Adamus, I know that you have checked and checked, but maybe it's time for another set of eyes. There is simply something wrong in the components or board traces.

 You voltage measurements on the opamp are:

 1= 0
 2=2.9
 3=2.3
 4=0
 5=0
 6=3.4
 7=24
 8=0

 Pin 3 is the reference input and is the correct voltage. Pin 2 is the sample voltage from the plate divided down by the resistor ratio (1M/30k). It is more positive than pin 3. Since the opamp is inverting the output voltage of the opamp must go negative with respect to the reference. But the O/P, Pin 6, is at 3.4V.

 It is almost as though the traces on your board are wired to make the opamp non-inverting. But, of course, this is impossible. So there has to be something else wrong. You say this is the right channel?

 The only other possibility is that the opamp is oscillating in your particular setup. Do you have a scope?


----------



## zkool448

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Until I get more time, this $4.50 rat shack plastic box will have to do 
	

	
	
		
		

		
			



_

 

It actually looks nice! And if it does the job, that's all that matters


----------



## olblueyez

I think it looks nice too. I think the opening for the tube could be a bit bigger, looks awful close to the plastic.


----------



## smeggy

I may open the tube hole a little but it's a temporary housing. There is about 2mm all around the tube and the plastic doesn't seem bothered by the heat at all. I's been on for hours on end with no problem. It feels like it runs pretty cool considering. The metal cased one got really hot, this one, with much greater ventillation (1" hole in the back too) dissipates heat very quickly and the case only gets luke warm.

 I was quite surprised at how well it allows cooling.


----------



## adamus

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Adamus, I know that you have checked and checked, but maybe it's time for another set of eyes. There is simply something wrong in the components or board traces.

 You voltage measurements on the opamp are:

 1= 0
 2=2.9
 3=2.3
 4=0
 5=0
 6=3.4
 7=24
 8=0

 Pin 3 is the reference input and is the correct voltage. Pin 2 is the sample voltage from the plate divided down by the resistor ratio (1M/30k). It is more positive than pin 3. Since the opamp is inverting the output voltage of the opamp must go negative with respect to the reference. But the O/P, Pin 6, is at 3.4V.

 It is almost as though the traces on your board are wired to make the opamp non-inverting. But, of course, this is impossible. So there has to be something else wrong. You say this is the right channel?

 The only other possibility is that the opamp is oscillating in your particular setup. Do you have a scope?_

 

I do have a scope, wht shall i test (i.e. which pins with respect to what?). 

 I even traced the schematic for compentant values..... they are all fine. maybe this is a trace issue, but ohming out the circuit suggets its ok. 

 could a bad cap do this?

 its the left channel by the way.


----------



## adamus

closeup of the suspect area


----------



## olblueyez

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_closeup of the suspect area_

 

Man I hope you get it going soon.


----------



## adamus

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Man I hope you get it going soon. 
	

	
	
		
		

		
		
	


	


_

 

i am in the lovely position of having the bijou to fall back on... not much stress with this one, and i am a bit of a weirdo and dont mind troubleshooting.


----------



## nux

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_closeup of the suspect area_

 

Do you have a photo of the underside too? I'll compare it to one of mine and see if I can spot anything.


----------



## olblueyez

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_i am in the lovely position of having the bijou to fall back on... not much stress with this one, and i am a bit of a weirdo and dont mind troubleshooting._

 

Good attitude! Somebody tell him how to fix this thing, its makin me nuts!


----------



## smeggy

whatever is wrong does seem baffling, especially to people like me who don't understand how any of this stuff works anyway. Good that you enjoy troubleshooting. It's a shame you're forced to listen to that other sucky amp until this is fixed... I feel your pain 
	

	
	
		
		

		
		
	


	




 hehe

 talking about Cavalli amps, my EHHA kit arrives tomorrow 
	

	
	
		
		

		
		
	


	




 Yippee!!


----------



## adamus

underside, with the temporary 11k resistor in place.


----------



## runeight

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I do have a scope, wht shall i test (i.e. which pins with respect to what?). 

 I even traced the schematic for compentant values..... they are all fine. maybe this is a trace issue, but ohming out the circuit suggets its ok. 

 could a bad cap do this?

 its the left channel by the way._

 

Look at pins 2,3, and 6 for oscillation.


----------



## sachu

*On the Proto Board:*
 Alex, Received parts today. I have replaced all the splitter BJTs.also replaced the TLE2426 to be safe. Replaced all splitter resistors as well. 

 R7S and R5S were burnt out completely.

 I will test the power supply section once again without the regulator chip to make sure Q1P is not burning up on account of the power supply.

 Do you think it would be a good idea to replace all the buffer BJTs as well before I turn it on? Or do I turn it on and see what happens?

 I have only BC550CTA BJTs left now..will they work?


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_talking about Cavalli amps, my EHHA kit arrives tomorrow 
	

	
	
		
		

		
			





 Yippee!!_

 

heh..finally!!
 I got parts for the EHHA heater supply section today. Bought the transformer as well..Had some case work to redo..its done now.

 Got a quote for anodizing the aluminium chassis, 50$ for clear or black finish.

 Wondering whether to get it done or go cheapand screw it...leave it ghetto. 

 Hope to have the amp running this weekend along with your CTH proto board and another CTh board.
	

	
	
		
		

		
		
	


	




 Gonna be busy sniffing solder smoke.


----------



## MrSlim

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_whatever is wrong does seem baffling, especially to people like me who don't understand how any of this stuff works anyway. Good that you enjoy troubleshooting. It's a shame you're forced to listen to that other sucky amp until this is fixed... I feel your pain 
	

	
	
		
		

		
		
	


	




 hehe

 talking about Cavalli amps, my EHHA kit arrives tomorrow 
	

	
	
		
		

		
		
	


	




 Yippee!!_

 

Where did you get the EHHA kit, and how much?


----------



## holland

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Where did you get the EHHA kit, and how much?_

 

x2


----------



## sachu

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_Where did you get the EHHA kit, and how much?_

 

Glassjaraudio has the kit if you ask Jeff.
 Total kit cost was around 110$ not including the required S22 supply or the heater supply.

 According to me a screaming deal....this amp is the best Cavalli Audio amp to my ears.


----------



## adamus

I scoped the opamp.... looks ok, a bit noisey but no obvious oscillations.


----------



## holland

adamus, can you humor me and remove the 11k resistor, and put an ammeter on the CRD leg you lifted? Using small clips might help, and going around the board if you need to. 

 There really are only 3 active components in this circuit. The CRD, the opamp, and the tube. We know 1) the tube is good 2) the opamp is good as swapping good side to bad side still resulted in bad. We also know that the opamp is not oscillating. That still points back to the CRD.

 The servo, also, basically has 3 start conditions (less, equal, greater). The other is to put a resistor in parallel with the cathode to drop the overall value down to move it to the other start condition. The current start condition is greater. I would like to see what happens when it moves to less.

 Thanks!


----------



## smeggy

EHHA arrived 
	

	
	
		
		

		
		
	


	




 CTH still purring nicely


----------



## dBel84

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_According to me a screaming deal....this amp is the *best * "?" Cavalli Audio amp to my ears._

 

 this gem has long been under the radar, perhaps this new love will help it earn its rightful place on the Cavalli podium. 

 excuse the thread hog 
	

	
	
		
		

		
		
	


	




 , glad to see so much CTH activity too - kudos to C & A for keeping at it..dB

 sorry had to edit that BEST comment - such an inflammatory adjective, suffice to say I would be happy if it were my only amp but I am spoiled to have the choice


----------



## sachu

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_this gem has long been under the radar, perhaps this new love will help it earn its rightful place on the Cavalli podium. 

 excuse the thread hog 
	

	
	
		
		

		
		
	


	




 , glad to see so much CTH activity too - kudos to C & A for keeping at it..dB

 sorry had to edit that BEST comment - such an inflammatory adjective, suffice to say I would be happy if it were my only amp but I am spoiled to have the choice 
	

	
	
		
		

		
		
	


	


_

 


 hehhe..I made sure I put in the obligatory disclaimer "To my ears".
	

	
	
		
		

		
		
	


	




 All thanks to you on getting this EHHA love going. Never would have heard one if it wans't for your amp.


----------



## smeggy

I'm looking forward to starting my EHHA when I feel a bit better, been sick for a couple of days so it's slow going. Should be fun if I don't screw it up 
	

	
	
		
		

		
		
	


	




 I really should get another Sigma 22 as well. I have a par metal slimline case that should work nicely with it and the smaller toroid I have here.

 On the CTH, I love the full bodied sound of it, very nice and musical, has me tapping my toes and bobbing m head, always a good sign despite looking like a Tupperware accessory in it's plastic tub


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I'm looking forward to starting my EHHA when I feel a bit better, been sick for a couple of days so it's slow going. Should be fun if I don't screw it up 
	

	
	
		
		

		
		
	


	




 I really should get another Sigma 22 as well. I have a par metal slimline case that should work nicely with it and the smaller toroid I have here.

 On the CTH, I love the full bodied sound of it, very nice and musical, has me tapping my toes and bobbing m head, always a good sign despite looking like a Tupperware accessory in it's plastic tub 
	

	
	
		
		

		
		
	


	


_

 

We should get a separate EHHA thread going..an EHHA build/impressions thread


----------



## smeggy

We should indeed, especially as it looks like there are a few interested parties in here to keep it running like the CTH, SOHA and Bijou threads.


----------



## adamus

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_adamus, can you humor me and remove the 11k resistor, and put an ammeter on the CRD leg you lifted? Using small clips might help, and going around the board if you need to. 

 There really are only 3 active components in this circuit. The CRD, the opamp, and the tube. We know 1) the tube is good 2) the opamp is good as swapping good side to bad side still resulted in bad. We also know that the opamp is not oscillating. That still points back to the CRD.

 The servo, also, basically has 3 start conditions (less, equal, greater). The other is to put a resistor in parallel with the cathode to drop the overall value down to move it to the other start condition. The current start condition is greater. I would like to see what happens when it moves to less.

 Thanks!_

 

Holland,

 I am away for the next three days (brothers engagement party). I will have a go at your suggestion onec back... and again, thanks for the advice.


----------



## holland

Adamus, have fun @ the party. I'm sure you'll have the new CRD in hand by then, so you can probably do the deed and report back. If you have time, or want to, you can run the different tests (before hand).


----------



## wiatrob

Yes, no thread hijacking 
	

	
	
		
		

		
			





 I'm kinda bummed H-wize is down and there's no access to the EHHA thread. Love my CTH's but giving this a go as well, need to decide active ground or fully balanced... Oh, I see Smeggy just started a thread here!

 Ok, back to our regularly schedled thread


----------



## holland

I'm starting to think the Headwize forums will never make it back.


----------



## sachu

Looks like we have yet anotehr CTH that lives..

 The proto board is up and runnig...

 Ther emight be a channel imbalnce (one of the buffer transistors maybe on the right channel)

 No smoke thus far.
 Check back later.

 Got one more CTh build for this weekend to come.

 Cheers,
 Sachu


----------



## smeggy

Great news!

 Let's hope it stays working this time 
	

	
	
		
		

		
		
	


	



 Now, get over to the EHHA thread, I need help


----------



## adamus

holland. 


 I just checked the current flowing through the CRD......

 bang on 2ma.

 volatge at pine 1 = 101v.

 we can rule out the CRD as a starter, we can rule out the opamp. 

 any more guesses?


----------



## runeight

There are only four possiblities:

 1. There is something wrong with the traces in the servo circuit.
 2. You have a wrong/bad/mis-oriented component in the servo
 3. The grid of the triode is not grounded through the leak resistor
 4. You are in the twilight zone

 I don't know which it is.


----------



## adamus

4, 100%


----------



## adamus

ignore me - a hypothesis quelled with logical thought.


----------



## runeight

probably not. if the volume control is set to zero the resistance across R1L will be zero ohms. even so, this value is ok because it means that the grid is grounded. which is where it needs to be.

 there MUST be something wrong with the servo components if the grid is grounded. or the traces are bad.

 is the opamp socket in the correct orientation?

 Edit: Nevermind.


----------



## adamus

runeight, the vol was at minimum so its ok. 

 I may end up removing all the omponents in the servo and starting again. Its just about got me completely stumped.


----------



## runeight

same here. i really don't know what the deal is.


----------



## holland

I'm lost as well. 

 1) You've also stated that the resistors are in the proper places, looking at the initial voltages, I would tend to agree.

 2) With the opamp removed, everything is working as it should. Opamp is known to be good. That leaves component and traces.

 Take another go through your pics, I guess. Nothing is jumping out.


----------



## adamus

I'll give it a going over tomorrow, I'll take out all the components, test them out of circuit, i think replacing the caps in the servo is probably sensible. 

 bizarre one!


----------



## adamus

moderator, can you forgive me swearing.....

 thank the F#####ng lord.

 all sorted. finally i tracked it down to a grounded opamp pin that should not have been grounded.

 its now making good music, but there is a fair bit of ground hum, particularly when i am near the vol knob.

 big thanks to holland and alex for the persistence

 do people find the 24v reg runs pretty hot?


----------



## smeggy

Congrats!

 That thing with the heatsink? If so, yeah. Toasty little sucker. I was even thinking of adding a bigger sink to it.


----------



## holland

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_moderator, can you forgive me swearing.....

 thank the F#####ng lord.

 all sorted. finally i tracked it down to a grounded opamp pin that should not have been grounded.

 its now making good music, but there is a fair bit of ground hum, particularly when i am near the vol knob.

 big thanks to holland and alex for the persistence

 do people find the 24v reg runs pretty hot?_

 

you're welcome, adamus. Might I ask, how did it get grounded? I take it you mean a servo opamp pin?

 Yes, the 24v reg runs hot. It's not horribly hot, though. I would say on the hotter side of warm.


----------



## holland

and congrats on getting it working. Way to persevere!


----------



## adamus

not out of the woods yet.....

 anyone identify this noise?


----------



## cfcubed

adamus - If you can hear the noise/hum it's not likely coming from the SM heater circuit because it runs @ 150khz (unless your hearing is REALLY good
	

	
	
		
		

		
			





 I think it is not uncommon in CTHs that, depending on various factors incl the tube used, a *very faint* 50hz/60hz _may_ be audible with very efficient cans.... Between songs or when no signal is present.

 If its more than that, I'd look at grounding (incl pot grounding) and would consider boxing it up & getting it away from all the nasty signals roaming around the bench.

 P.S. Even though we incorp a ripple filter in the SM heater circuit, it is possible that some insignificant amount of ripple is still present in the heater supply. During prototyping, I couldn't tell battery-powered heater from this SM implementation, so think this should not be a factor. I bring this up because you should report the frequency & magnitude of that wave you are showing to assure its the audible-range one that you are hearing.


----------



## adamus

ok, just switched to the senns (650's), hum is reduced but still there slightly (very quiet).


----------



## tacitapproval

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I think it is not uncommon in CTHs that, depending on various factors incl the tube used, a *very faint* 50hz/60hz may be audible with very efficient cans.... Between songs or when no signal is present.

 If its more than that, I'd look at grounding (incl pot grounding) and would consider boxing it up & getting it away from all the nasty signals roaming around the bench._

 

Speaking of this, is there any way to bring down this noise? With full size cans I don't hear it, but with iem's I do, and with my better, more sensitive pair (Sleek SA6) it's loud enough to be distracting. It does vary some from tube to tube. I should note that this is with r18's at 150ohms and plastic end panels, so no grounding issues there. 

 I am loathe to mess with this now that it is working well, and the amp is perfectly enjoyable with all of my headphones save the SA6. I would though like to be able to listen to them in bed with this, but that may be out of reach.


----------



## runeight

Noise/hum would either be grounding issues or bad Q3P/Q4P. Is the noise in both channels?


----------



## adamus

yes, but slightly stronger in the left, only very slightly.


----------



## smeggy

I hope you get it perfect because it's a phenomenal little amp, it's nicely above the Starving Student right now.


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I hope you get it perfect because it's a phenomenal little amp, it's nicely above the Starving Student right now._

 

wait till you get the Semens ECC82 Smeggy..a whole new level.. Got an Amperex 6DJ8 in mine right now while I work on the EHHA..fantastic!


----------



## adamus

tomorrow i will try grounding the pot, it gets much worse if i touch the pot...

 i think the 8416 will be extremely hard to beat in this amp. even with the very slight hum, the 8416 is sounding superb. 

 its a superb little amp and i must let it burn in but currently the bijou is in another league. 

 I have now moved the bijou into the bedroom where is can be heard with no noise from the fiance! The CTH is now the amp next to the computer for evening listening when i am working etc. my desk now seems huge!


----------



## smeggy

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_wait till you get the Semens ECC82 Smeggy..a whole new level.. Got an Amperex 6DJ8 in mine right now while I work on the EHHA..fantastic!_

 

Sweet, are the Siemens in yet?


----------



## tacitapproval

My noise is in both channels, but the balance as well as total quantity depends on which tube is used. Some tubes are much noisier on one side than the other.

 I certainly don't hear anything with HD650s though.


----------



## olblueyez

The ECC82 is working out for you?


----------



## sachu

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_The ECC82 is working out for you?_

 

Can't wait for it..expecting it any day now..I have a bunch of other tubes to tide me over for the moment though.


----------



## olblueyez

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Can't wait for it..expecting it any day now..I have a bunch of other tubes to tide me over for the moment though._

 

I cant wait to hear what you think. It should livin things up a bit, most tubes are too warm and rolled off or bright like the RCA cleartop but the Siemens is is nice and clear and smooth and has a tiny kick in the bass department. If you try it and hate it, send me a PM ok.


----------



## tacitapproval

Anyone else had any luck with iem's and the CTH? Or, is this unreasonable?

 Also, what would be the negative result of overspecing R18 to 200ohms? 150 is definitely quieter than 56 was. Tell me why this is a bad idea.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_Anyone else had any luck with iem's and the CTH? Or, is this unreasonable?

 Also, what would be the negative result of overspecing R18 to 200ohms? 150 is definitely quieter than 56 was. Tell me why this is a bad idea._

 

I believe I posted that the CTH worked with my Sennheiser IE8 without noise, but with the Mullard tube I was using there was more bass than I cared for (an IE8 problem I've been complaining about).


----------



## tacitapproval

The ie8 is even more sensitive than the sa6, so hmmm... I wonder what accounts for my problem.


----------



## cfcubed

tacitapproval - runeight's suggestions aside, I do get the faintest hum, noticeable between songs w/my D2000s, on both my CTH builds _under certain conditions_. Don't recall it being noticeable w/my less efficient, hi-Z DT-880s. 

 I do recall some others mentioning they detected this too, but I think what cans you use, what you place the CTH near (electrically speaking), what tube type used, and perhaps other things affect this. E.g. I found a couple of my 12AU7 variants the most quiet in this regard. 

 So don't _think_ its unique to your build. Would like to track it down in my build(s) someday, but as the amp sound so good & the hum level is not detectable when musics playing, its low priority.


----------



## tacitapproval

My experience concurs with yours cf. Tube definitely has the greatest impact on the hum. It is more a niggling issue only because I often want to use this bedside at very low volume with iems, otherwise any noise from it is pretty negligible. To that end, I went ahead and ramped up r18 to 200ohms (actually 221, it's what I had)--noise is somewhat lower (not gone) and I don't notice any obvious degradation of signal quality.


----------



## nux

I had some hum when using it with my Gamma1 DAC running on DC power. Using USB power eliminates it.


----------



## tacitapproval

The noise I am describing is not source dependent.


----------



## MrSlim

Are you using shielded cables from the input to the pot and then to the board? I had some hum while I was using unshielded wire. Once I replaced the input and output cabling with shielded, it resolved the hum problem..


----------



## tacitapproval

I did have shielded cable on it. I ended up removing them because of space and flexibility concerns, this in turn lead to problems with some stray shielding wires causing havoc on the board. It also did not alleviate the noise, although I can't now say whether or not it improved things versus the unshielded wires, as I don't remember well enough.


----------



## runeight

If the noise is dependent on the tube there are really only five possibilities:

 1. Coming from the input. Possible if the input wires are exposed.
 2. Coming from the B+. Possible, but the B+ is very well filtered and the CCS really rejects ripple.
 3. Radiation from the PS section directly into the tube. This is also possible given the close spacing and the vertical diodes. But if it doesn't happen on all of the amps then it's hard to see why this would happen in some cases and not in others.
 4. General EM from the surroudings. I guess your noise is not location dependent?
 5. Grounding. This is always the toughest nut to crack. But the star ground scheme should solve this provided that the pot is wired correctly.

 You might check out Q3P and Q4P, but this is a long shot. Definitely not a heater problem because the heater is running at 150kHz behind the chokes.


----------



## nux

Question, would increasing the value of C4 improve the bass response? Or is the input impedence into Q4/Q5 sufficiently high that it would not make a noticeable difference increasing C4 to 470nF/1uF?


----------



## zkool448

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_tomorrow i will try grounding the pot, it gets much worse if i touch the pot...

 i think the 8416 will be extremely hard to beat in this amp. even with the very slight hum, the 8416 is sounding superb._

 

All my amps have isolated pots including the CTH (still uncased). They all _had_ that "hum" noise you describe, that same irritating hum that gets worse when you touch the pot. The wire trick from pot shaft to SG have eliminated all my hum/noise issues (aside from a recent noise I discovered with my SOHA II where it needed a ground loop breaker but that's another story).

 My CTH is dead silent regardless of source or volume level, *HOWEVER*, this is only true if I'm using my 12AU7 tube. I can always hear a different kind of hum simply by swapping the tube with either one of my 6N1Ps (with heater set to 6.3v). The hum is very faint, and does appear to be slightly stronger in the left channel.


----------



## keyid

mines also close to zkool's 12au7 its quiet. With 6n1ps it has an irritable hum and they are interesting tubes, im beginning to really like.


----------



## adamus

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_All my amps have isolated pots including the CTH (still uncased). They all had that "hum" noise you describe, that same irritating hum that gets worse when you touch the pot. The wire trick from pot shaft to SG have eliminated all my hum/noise issues (aside from a recent noise I discovered with my SOHA II where it needed a ground loop breaker but that's another story).

 My CTH is dead silent regardless of source or volume level, *HOWEVER*, this is only true if I'm using my 12AU7 tube. I can always hear a different kind of hum simply by swapping the tube with either one of my 6N1Ps (with heater set to 6.3v). The hum is very faint, and does appear to be slightly stronger in the left channel._

 

Cheers Zkool448, I'll ground the pot and see what happens, I will also switch to shielded wire. 

 I switched in a 6n1p and as you suggest, the hum did get stronger but if i recall correctly, the 6n1p is a higher gain tube, so it could just be magnifying residual hum.


----------



## zkool448

Possible indeed. At least we have some idea that some tubes are culprit to some of the noises we hear


----------



## tacitapproval

I too find the 6n1p to be noisier than 12au7 varieties, although within this group the individual tubes vary. I have four 6n1ps and each has a different amount of noise and more or less noise on one side or the other.


----------



## TimJo

I have also found when running 12AU7's that the background hum is minimal. The 6n1p's bring it out more. I haven't decided if it's simply due to gain (as adamus suggested) or if it's something particular to the 6 volt heater mode in general.

 I haven't spent much time worrying about it mainly because I don't notice it at normal listening volumes, and because I have settled on using one tube for the last several weeks. I'm really loving the sound of the CBS-Hytron 7318 the best of all the tubes I've tried so far. It really makes my DT880's shine...


----------



## smeggy

Odd, the one sachu made for me is totally silent but I don't use IEMs so can't test with really sensitive drivers but I did wazz it up full and touched various parts... nothing! 

 I really like this amp.


----------



## tacitapproval

This "tube noise" that, I think, we've reached a consensus on, at least that 6n1ps are noisier, is not volume dependent. In fact, I hear it with the pot all the way down. It also does not involve touching anything.

 The noise that gets louder when the pot is touched is, at least for me, volume dependent and not present when there is a source on the input.


----------



## runeight

If the tube noise increases with increasing mu then the problem is most likely noise at the input grids or ground noise from the line or other devices.


----------



## tacitapproval

I'm not so sure it is mu related. For instance, my 6211 is pretty quiet and is 27 amplication factor to 6n1p's 33, not so much difference, and no louder than 12bh7 at only 15 (actually my 12bh7 is noisier than it.)

 This actually makes me think it is about higher current draw.


----------



## runeight

you mean higher draw from the heater supply? That certainly fits your pattern.

 This is possible since higher draw means larger current spikes in the heater rectifiers and filter caps. More radiation and less good filtering.

 cfcubed, do your heater circuit calculations permit someone to put a larger cap in for C3H? This would be a very interesting test.


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_This actually makes me think it is about higher current draw._

 

My hotel room is a bit loud, but I can hear the very faintest buzz with volume all the way down - 

 Very low with 12AU7s
 Slightly louder with 8416
 Same with 6922
 Slightly louder still with 6H30 

 Which would lead credence to the heater current theory..

 BUT I don't recall hearing this except on a couple of tubes in the past...


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_My hotel room is a bit loud, but I can hear the very faintest buzz with volume all the way down - 

 Very low with 12AU7s
 Slightly louder with 8416
 Same with 6922
 Slightly louder still with 6H30 

 Which would lead credence to the heater current theory..

 BUT I don't recall hearing this except on a couple of tubes in the past..._

 

Maybe the hotel room would be quieter if you send the hookers away?


----------



## adamus

runeight, did my scope pics give any clue to the hum?

 also, whilst it was being scoped, i did notice the offset wanders between 0 and 3mv quite quickly, would this indicate anything unusual or is it just the behavious of the buffers and servos


----------



## sachu

Alex, is it possible to wire two of these boards in bridge mode with dual supplies? OR does it suffer the same problems as a balanced config would..the dual splitters having an imbalance between them?


----------



## runeight

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_runeight, did my scope pics give any clue to the hum?

 also, whilst it was being scoped, i did notice the offset wanders between 0 and 3mv quite quickly, would this indicate anything unusual or is it just the behavious of the buffers and servos_

 

adamus, what were you measuring in that picture?

 offset wander 10mV or less is ok and normal. even more than this would be ok.


----------



## adamus

output signal with inputs shorted.


----------



## runeight

what's the scale on the y axis? and can you do some measurments on different tubes with different heater currents?


----------



## cfcubed

_cfcubed, do your heater circuit calculations permit someone to put a larger cap in for C3H? This would be a very interesting test._

 Let me take a look at the info I have on heater parts values. It's been a while.
 For sure the SM heater is "chopping" more to put out 6V from its 33V or so input vs. 12v.
 Another interesting test would be to disable the switcher & use a very clean 6V heater supply like a battery. I did such a test on the P2P POC & did not notice a difference in any noise. But the POC's layout, etc. was very different than the CTH PCB (more spread out, etc.)

  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_what's the scale on the y axis? and can you do some measurments on different tubes with different heater currents?_

 

Would be nice to get an idea of the frequency of that wave too.


----------



## adamus

y axis is 5mv per division

 x axis is 10u secs, so high frequency.

 no obvious change on when subbing in a 6n1p


----------



## holland

can you overlay traces of the heater on the second channel? should be pin 4 and 5, voltage relative to real ground.


----------



## adamus

holland, i can btu not tonight, I was given the scope a few days ago, and dont have the right probes. 

 here is a pic of thre scope looking at lower frequencies.


----------



## nux

Just two quick questions:

 With my headphones (MS-1's, 32 ohm), I only have to turn the pot about 1/3rd around to get the maximum volume I'd want. I am using 100 ohm resistors for R18L/R. Would roughly doubling R18 give me more control with the pot? And will this decrease the noise present?

 Secondly, would increasing the value of C4 improve the bass response? Or is the input impedence into Q4/Q5 sufficiently high that the low frequency response is not effected?


----------



## sachu

Finished my 4th one. Here is the CTH parking lot..The middle one is going to stay with me. The one closest is heading over to Japan.


----------



## runeight

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_Just two quick questions:

 With my headphones (MS-1's, 32 ohm), I only have to turn the pot about 1/3rd around to get the maximum volume I'd want. I am using 100 ohm resistors for R18L/R. Would roughly doubling R18 give me more control with the pot? And will this decrease the noise present?

 Secondly, would increasing the value of C4 improve the bass response? Or is the input impedence into Q4/Q5 sufficiently high that the low frequency response is not effected?_

 

Yes to the first question.

 You are correct about the buffer. Its Zi is so high that increasing C4 is unlikely to affect the base response. Are you hearing variations in base with different tubes?


----------



## sachu

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_ Are you hearing variations in base with different tubes?_

 

I do with my CTHs.


----------



## nux

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Yes to the first question.

 You are correct about the buffer. Its Zi is so high that increasing C4 is unlikely to affect the base response. Are you hearing variations in base with different tubes?_

 

Excellent. Yes I am hearing different bass with different tubes, I just wanted to check that C4 wasn't holding it back at all. I'll put in a larger R18 soon, thanks.


----------



## phangtonpower

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_The one closest is heading over to Japan._

 

Nice!! Wish I could have built it myself. Can't wait to test it out


----------



## smeggy

Cool beans sachu. I'm sure it'll enjoy it's stay. I'm kinda jealous of it really, I've never been to Japan


----------



## sachu

Quote:


  Originally Posted by *phangtonpower* /img/forum/go_quote.gif 
_Nice!! Wish I could have built it myself. Can't wait to test it out
	

	
	
		
		

		
		
	


	


_

 

hahha...I am sure you will enjoy it a lot.

  Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Cool beans sachu. I'm sure it'll enjoy it's stay. I'm kinda jealous of it really, I've never been to Japan 
	

	
	
		
		

		
		
	


	


_

 






..Thanks Smeggy.


----------



## holland

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Finished my 4th one. Here is the CTH parking lot.._

 

You're like a factory. I just mailed off my second to my bro as a gift, 2 more to build. That's not quite the pace other builders are going at.


----------



## sachu

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_You're like a factory. I just mailed off my second to my bro as a gift, 2 more to build. That's not quite the pace other builders are going at._

 






 Basically dedicated 2 days to this ****...tested the EHHA and built two CTHs...productive wouldn't you say


----------



## cfcubed

Won't have time to tinker for a bit, but wanted to put up info.

 At issue here is that it seems common that w/sensitive, lo-Z cans & 6,3v heated tubes, a noise/hum can be heard. For most, this does not intrude on music but is heard between songs. Use of design-center 12au7 variants lessen the noise.

 I'm giving design info here, but if/when I get time these are the experiments in order that I'd conduct:
disable switcher by disconnecting its supply. lift output of 3uH & use clean 6V heater supply (e.g. batt) for pins 4/5. See if noise disappears, just to be sure switcher is involved.
if this confirmed switcher is causing the noise, restore 3uH & introduce resistance between lifted switcher input leg & connect. Resistor should handle load (e.g. 5W?)
Perhaps alter cap values.

 If switcher is found the culprit (1st experiment), I'd suspect we're asking a lot of it to cut from its supply (about 33V, its max is 40V) all the way down to 6.3V. Its min is stated as 1.2V but I'd suspect an ugly waveform at that voltage.
 So, the 2nd experiment would be to alleviate some of the load through a resistor.

 Here are National's Simple Switcher results at 6.3V & 12.6V:





 WRT above, note that our input (Cin) & output (Cout) caps are higher than required, a good thing I'd suppose. 

 Note also that ideal main coil values vary between the two (220uH, 330uH), but in this next snip of the datasheet, 220uH appears best compromise value (& much smaller as well):




 Now the ideal ripple filter cap _may_ be a bit higher (180uF) than we are using (100uF). BUT we are getting very nice ripple reduction vs switcher w/o ripple reduction (see scope image from spec above). And in P2P proto I used a "worse" switcher (LM2575 - 52kHz) with NO ripple filter & found it to work well. So what _may_ be happening @ 6.3V is the actual chop freq (or a harmonic of it) is entering audible range. More research would need to happen to reach that conclusion. Alleviating some of the switchers job through resistance OR altering assoc cap values might then address this.


----------



## tacitapproval

How much resistance would you suggest? Would wirewound be sufficient for this? 

 You're suggesting upping C1H and C2H to 180uF, right? What about C3H that Alex asked about?

 I'm not sure how to impliment the battery test you suggest first (I'm still very much a noob). This would require something fairily heavy duty to put out the amps required, or am I missing something?


----------



## cfcubed

Again I write too much in a post
	

	
	
		
		

		
			





 But wanted to get the basis/details of the heater supply out there.

 My quick thoughts (look at PCB traces/images + switcher spec doc LM2595.pdf):
A battery test for heater would be nice to be sure we're barking up the right tree. Thinking one would lift LM2595 pin #2 / Vin (see LM2595.pdf) & lift output leg of L1H (one closest to C10P). One could tape together 4 D cells to make 6V+ & connect neg to heater ground (tube socket pin 5 ?) & pos to heater + (tube socket pin 4 ?). See if noise is gone.
If confirmed noise is from switcher, only C1H in ripple filter _could_ go to 180uF. C3H & C2H are already above mins reported by SS tool. Raising them would be a future test. And I'd try resistor bit (next) 1st.
After battery test confirmed switcher is noise-maker, I'd try to reduce voltage into switcher by 10V or so. So I'd reconnect L1H & start w/20-40ohm 3W resistor of any type between lifted LM2595 pin #2 & its pad. Targeting something <= 24V as input to switcher under load.

*Edit: added some detail*


----------



## tacitapproval

Thanks for the clarifications.


----------



## adamus

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_holland, i can btu not tonight, I was given the scope a few days ago, and dont have the right probes. 

 here is a pic of thre scope looking at lower frequencies._

 

any idea on how to interpret this? not being an EE, anyone explain the two traces (off one channel). 

 timebase is 2ms per division. looks like some ground noise on there?


----------



## zkool448

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I have a quick question for all you CTH geniuses. 

 I have a spare switched pot from an AMB mini3 and was wondering if I could use that as the main power switch as well as pot. It seems a more elegant solution to using a separate switch for power._

 

smeggy, i have a spare one of these. I think it's the exact pot as the one your using in your CTH, it's the RK097 -- No ill effects then? I might do the same if so. 

 Also, are the pins numbers the same as the one from the BOM (except for the extra 2 pins at the back for on/off operation)?


----------



## dBel84

I don't think those switches can handle much current or voltage , need to check the data sheet ..dB


----------



## smeggy

I thinks it's wired the same but can't remember for sure.. memory like a sieve 
	

	
	
		
		

		
		
	


	




 I didn't end up using the power function on the switch after all but it should work fine if The wire is routed away from the components.


----------



## smeggy

Quote:


  Originally Posted by *dBel84* /img/forum/go_quote.gif 
_I don't think those switches can handle much current or voltage , need to check the data sheet ..dB_

 

I think someone (MisterX?) said their volt/current capacity should work fine. It's a few pages back where I asked the question I think.


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I think someone (MisterX?) said their volt/current capacity should work fine. It's a few pages back where I asked the question I think._

 

Based on Specifications switches it sounds a bit much to me for the little bugger - 3A 16V DC... Think we're looking at like 24VAC 1A in a CTH.


----------



## zkool448

yikes... I thought smeggy ran an AC line for the vol/pwr switch to the front (accross the board) and hoping no noise/hum introduced ...*but* he's not even using the switch! 
	

	
	
		
		

		
		
	


	




 Anyway, i only wanted to know if i can save an extra hole in the back. thanks.


----------



## smeggy

That was my original plan, but I went with a seperate switch anyway


----------



## zkool448

Ok so reviewing this diagram, if I end up using the rk97 pot, what do you folks recommend is the best way to route the ac wire? (i.e. stay as far away from which components, run from top, bottom, L/R sides?)


----------



## sachu

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_Ok so reviewing this diagram, if I end up using the rk97 pot, what do you folks recommend is the best way to route the ac wire? (i.e. stay as far away from which components, run from top, bottom, L/R sides?)_

 

Run it from the rightmost bottom side to the left most bottom side.


----------



## zkool448

cool thanks


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_How much resistance would you suggest? 
 I'm not sure how to impliment the battery test you suggest first (I'm still very much a noob). This would require something fairily heavy duty to put out the amps required, or am I missing something?_

 

TA - I know the hum is bugging you with IEMs - and I'm certainly NOT impugning your skills - but given the amount of effort you've gone to to get this amp working...

 I may be able to test CF's battery suggestion this weekend. Althugh CF already did this test during the perfboard proto. 
	

	
	
		
		

		
		
	


	




 The most straightforward way to test would seem to be cutting the traces to pins 4&5 and applying the battery there... I'd rather jumper traces than lift Vreg pins - it's really tight back there. 

 My question is - why didn't I notice this noise before? I think this hum is due to the power of suggestion


----------



## keyid

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_




_

 

Nice Diagram


----------



## adamus

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_TA - I know the hum is bugging you with IEMs - and I'm certainly NOT impugning your skills - but given the amount of effort you've gone to to get this amp working...

 I may be able to test CF's battery suggestion this weekend. Althugh CF already did this test during the perfboard proto. 
	

	
	
		
		

		
		
	


	




 The most straightforward way to test would seem to be cutting the traces to pins 4&5 and applying the battery there... I'd rather jumper traces than lift Vreg pins - it's really tight back there. 

 My question is - why didn't I notice this noise before? I think this hum is due to the power of suggestion 
	

	
	
		
		

		
		
	


	


_

 

are we coming to the conclusion that most people are experiencing hum to some degree? that is a genuine question - but there seems to be a lot of us hearing hum. 

 With a 12au7 its minimal, but stick in a 6n1p, or even a 6dj8 and its noticable to my ears.

 I am sure with some collective effort we can crack it if so.


----------



## smeggy

I feel left out now because I don't have any hum


----------



## adamus

what tubes though? 12au7s are quiet.

 Also, are you using shielded wire, if so are you grounding the sheild?


----------



## Forte

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_are we coming to the conclusion that most people are experiencing hum to some degree? that is a genuine question - but there seems to be a lot of us hearing hum. _

 


 I do have a hum but not at listenable volumes. Hum can be heard at approx 50% volume(using 56R output resistors) which is louder than I would listen at and only with no music playing. This is with 12.6v tubes, haven't listened to any 6.3v tubes for a while, will swap tubes tonight and check over the weekend.

 From what I remember changing coupling caps from BOM to Sonicaps did make the hum appear at a lower volume level, it wasn't apparent until 85-90% volume when I had the BOM caps in.


----------



## sachu

all the 4 CTH amps I have built don't seem to have this hum or hiss..I have tried my 6N1P and an amperex 6DJ8


----------



## adamus

and did you use shielded cabling?


----------



## HeadphoneAddict

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_are we coming to the conclusion that most people are experiencing hum to some degree? that is a genuine question - but there seems to be a lot of us hearing hum. 

 With a 12au7 its minimal, but stick in a 6n1p, or even a 6dj8 and its noticable to my ears.

 I am sure with some collective effort we can crack it if so._

 

I NEVER heard any hum with the loaner CTH from wiatrob and Mullard short plate, even with very sensitive IEM.


----------



## adamus

brilliant. This is just what i wanted to hear. thanks chaps. 

 over the weekend i will try and track down my hum issue.


----------



## sachu

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_ and did you use shielded cabling? ._

 

No..none of them use shielded cabling in them. Plain hookup wire.


----------



## adamus

if i turn the vol right i up i get a fair bit of white noise. There is also a low level (sounds hgher than 100hz). 

 all volatges check out, all looks good. I'll do an inspection.


----------



## sachu

do you have a pic of your amp? 

 Also what pot are you using? Have you tried grounding the pot case to SG on the board?


----------



## adamus

rk09, there is a pic a few pages back.

 I'll try the input wiring first. with no tube its silent, so its definately the input stage that is creating the noise.


----------



## cfcubed

_I may be able to test CF's battery suggestion this weekend. Although CF already did this test during the perfboard proto. 
	

	
	
		
		

		
		
	


	




 From what I remember changing coupling caps from BOM to Sonicaps did make the hum appear at a lower volume level, it wasn't apparent until 85-90% volume when I had the BOM caps in.

 No..none of them use shielded cabling in them. Plain hookup wire. _

 Couple things:
This reminded me I've non-BoM C4 caps in BOTH my builds. And I know that a couple others that mentioned hum did also (TimJo). *So non-BoM couplers could be involved. *
I shielded my input runs, *but larger C4s added between 2 & 4 inches of unshielded wire to the input stage.*
wiatrob - Don't see you doing experiments if you don't hear the problem
	

	
	
		
		

		
		
	


	


Seems the CTH listeners reporting noise/hum is in the minority, so again build variation, high-sensitivity/low-Z cans & 6.3V 300ma+ heated tubes may be factors.

 But even the minority hearing this very faint noise/hum between tracks seem to report they really like the amp... And for many it has become their primary amp (often displacing other DIY amps.) 

*IOW, think this issue is a very minor one affecting a minority of CTH builds/listeners. * E.g. in my case, its sooo minor I'm not motivated to open the case to experiment


----------



## tacitapproval

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_TA - I know the hum is bugging you with IEMs - and I'm certainly NOT impugning your skills - but given the amount of effort you've gone to to get this amp working...

 I may be able to test CF's battery suggestion this weekend. Althugh CF already did this test during the perfboard proto. 
	

	
	
		
		

		
		
	


	




 The most straightforward way to test would seem to be cutting the traces to pins 4&5 and applying the battery there... I'd rather jumper traces than lift Vreg pins - it's really tight back there. 

 My question is - why didn't I notice this noise before? I think this hum is due to the power of suggestion 
	

	
	
		
		

		
		
	


	


_

 

Yes, but the good news is I have learned more from this build than any other I have done. So, there is a silver lining to my frustration. To be honest, I was planning to skip the battery test and try out the resistor mod straight off. Sorry to be the little voice of doubt.

 To others -- I must reiterate, the noise I hear is not volume dependent, but is highly tube dependent and is only observable with sensitive iems. If you have some, try turning pot all the way down and listening, preferably with 6n1p or other high current tube.


----------



## tacitapproval

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_[*]This reminded me I've non-BoM C4 caps in BOTH my builds. And I know that a couple others that mentioned hum did also (TimJo). *So non-BoM couplers could be involved. * [*]I shielded my input runs, *but larger C4s added between 2 & 4 inches of unshielded wire to the input stage.*[*]wiatrob - Don't see you doing experiments if you don't hear the problem
	

	
	
		
		

		
			





[/LIST]
_
_


I am using the wimas Bill provides, so non-BOM, but no long leads.

 There did seem to be a number of builders who heard noise with the 6n1p. It may be useful to mention what headphone is used to test. For instance, I don't hear it with 32ohm px-100, and hear it somewhat with 32ohm RE2, but do hear it most clearly with 50ohm SA6, so I think sensitivity and the nature of iems and maybe even armatures bring it out._


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I NEVER heard any hum with the loaner CTH from wiatrob and Mullard short plate, even with very sensitive IEM._

 

And from looking at Sherwood's review, he heard a slight hum on my Proto. I need to collect that amp when Blutarsky is done with it and do a side by side. 

 That's the proof build an it actually has socketed coupling caps (Wimas in both my builds) so it has 'longer' leads.


----------



## cfcubed

I plan to conduct the tests as I suggested them within the next week, if y'all can wait that long
	

	
	
		
		

		
		
	


	




 I'll be doing this on my 2nd CTH w/more room + bottom mounted heater reg so it will be easier to fiddle. Again, disabling the switcher entirely & trying 6V batt heater supply... If noise/hum disappears will lower switcher Vin to < 24V w/resistor & see if that helps.

 I plan to pull the Mundorf S+Os & replace w/Sonicap Gen Is and will try to shield their leads (& ground the shields). We have a lot going on in a small space.

 OK enough for me for now, need "Less posting, moar building" as Nate posted elsewhere


----------



## Forte

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_But even the minority hearing this very faint noise/hum between tracks seem to report they really like the amp... And for many it has become their primary amp (often displacing other DIY amps.)_

 

Absolutely! Still the most enjoyable and engaging amp I have heard, my other amps are gathering dust.
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I plan to conduct the tests as I suggested them within the next week, if y'all can wait that long 

 I plan to pull the Mundorf S+Os & replace w/Sonicap Gen Is and will try to shield their leads (& ground the shields)._

 

Look forward to hearing the results of your tests, especially the shielding of the cap leads.


----------



## zkool448

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_Nice Diagram 
	

	
	
		
		

		
		
	


	


_

 

Yeah, it's awesome and very detailed isn't it? Thanks to Ric Lee for making it 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I feel left out now because I don't have any hum 
	

	
	
		
		

		
		
	


	


_

 

smeggy, I recall you have cans that come with hookup wires that can be connected directly to your A/V receiver's speaker outs 
	

	
	
		
		

		
		
	


	




 ...that or unless sachu uses proprietary components when he builds them


----------



## adamus

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Absolutely! Still the most enjoyable and engaging amp I have heard, my other amps are gathering dust.
	

	
	
		
		

		
		
	


	


_

 

Its a good amp, and for the size its very good. But the bijou is in another class, both in sq and COST!


----------



## holland

Good to know. I'll be joining the Bijou crowd soon. I finally got motivated to get off my ass and finish it, I finished air wiring my tube sockets last night. 2 years in the making, sitting in a case without wire....I absolutely hate wiring, panel work, etc.


----------



## TimJo

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_*IOW, think this issue is a very minor one affecting a minority of CTH builds/listeners. * E.g. in my case, its sooo minor I'm not motivated to open the case to experiment
	

	
	
		
		

		
		
	


	


_

 

This has been my feeling as well. I'd rather keep listening to it than take the time to fiddle with it... 
	

	
	
		
		

		
		
	


	




 But I was wondering about the non-bom interstage cap theory. The way I mounted the VitQ's, I suppose I could be picking something up via the leads.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_And from looking at Sherwood's review, he heard a slight hum on my Proto. I need to collect that amp when Blutarsky is done with it and do a side by side. 

 That's the proof build an it actually has socketed coupling caps (Wimas in both my builds) so it has 'longer' leads._

 

Are they two different amps? And if not different amps, could the difference be the tubes we used? I was too lazy to try anything but my Mullards.


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_And from looking at Sherwood's review, he heard a slight hum on my Proto. I need to collect that amp when Blutarsky is done with it and do a side by side. 

 That's the proof build an it actually has socketed coupling caps (Wimas in both my builds) so it has 'longer' leads._

 

The one I built for Smeggy actually has sockets for the coupling caps. However I did install BOM caps on his amp.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Are they two different amps? And if not different amps, could the difference be the tubes we used? I was too lazy to try anything but my Mullards._

 

One is built on the Proto PCB and one on the production PCB. I did talk to Sherwood this afternoon. The noise he heard was without music playing, with volume cranked. I hear noise on ALL tube amps in that scenario.

 There is virtually NO difference between the two PCBS. BUT - the proof build you had does have higher amperage inductors - it's rated to run the 6H30 - I think 1 and 1.25 Amps. I sent a set to Holland, but don't know if he's tried them.

 I'm about to curl up with mine and this Siemens ECC82 Chrome Plate...


----------



## Forte

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_Its a good amp, and for the size its very good. But the bijou is in another class, both in sq and COST!_

 

Glad to hear that. I have a set of Bijou boards from the original group buy that I can finally start to build having found a budget chassis at last. Won't be as desktop friendly though given its size.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_One is built on the Proto PCB and one on the production PCB. I did talk to Sherwood this afternoon. The noise he heard was without music playing, with volume cranked. I hear noise on ALL tube amps in that scenario.

 There is virtually NO difference between the two PCBS. BUT - the proof build you had does have higher amperage inductors - it's rated to run the 6H30 - I think 1 and 1.25 Amps. I sent a set to Holland, but don't know if he's tried them.

 I'm about to curl up with mine and this Siemens ECC82 Chrome Plate... 
	

	
	
		
		

		
		
	


	


_

 

I have a new Siemens E82CC (according to the box) still here in the shrinkwrap.


----------



## sachu

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I have a new Siemens E82CC (according to the box) still here in the shrinkwrap. 
	

	
	
		
		

		
		
	


	


_

 

Give you 5$ for it


----------



## keyid

im really enjoying my Siemens 5814A triple mica just got them the other day


----------



## sachu

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_im really enjoying my Siemens 5814A triple mica just got them the other day_

 

do you have one that you would be willing to part with? If so PM me please..kinda interested. I seem to have an RCA black plate 5814A


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_I have a new Siemens E82CC (according to the box) still here in the shrinkwrap. 
	

	
	
		
		

		
			



_

 

OF COURSE you do Larry


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_OF COURSE you do Larry 
	

	
	
		
		

		
		
	


	


_

 

The Siemens is for my EF1, but I am going to see if I can send the EF1 back to get the electronic controlled volume knob "tuned" so that it doesn't leak so much volume at zero and has less channel imbalance at low volumes. When I get it back then I'll try the Siemens, unless I end up with a CTH somehow and then I'll pop it's cherry in one of those instead.


----------



## keyid

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_do you have one that you would be willing to part with? If so PM me please..kinda interested. I seem to have an RCA black plate 5814A_

 

sorry only have one, they were probably the most I spend on a single tube. I do have an Siemens E82cc that is noisy if you want that, its sounds good but has an annoying hum. I also not to long ago got an RCA short black plate, 2 mica, jrc-5814a from 1960's, i thought it added a lot of weight and has a lucid flavor.


----------



## sachu

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_sorry only have one, they were probably the most I spend on a single tube. I do have an Siemens E82cc that is noisy if you want that, its sounds good but has an annoying hum. I also not to long ago got an RCA short black plate, 2 mica, jrc-5814a from 1960's, i thought it added a lot of weight and has a lucid flavor._

 

naa..thanks for the offer though. I should be receiving a Siemens E82CC any day now. 
	

	
	
		
		

		
		
	


	




 The 5814A I have are RCA long black plates.

 Looks like it is time I visited my surplus store and see what else he's got.


----------



## olblueyez

Sylvania GB (Gold Brand w/gold pins) 5963 or 5814A. Seems like the CTH comes across a tad brighter than my amp and the GB's are as smooth as it gets. Just something to keep in mind if you see one.


----------



## olblueyez

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_sorry only have one, they were probably the most I spend on a single tube. I do have an Siemens E82cc that is noisy if you want that, its sounds good but has an annoying hum. I also not to long ago got an RCA short black plate, 2 mica, jrc-5814a from 1960's, i thought it added a lot of weight and has a lucid flavor._

 

Can you tell us more about the sound of the Siemens tube with the CTH?


----------



## sachu

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Sylvania GB (Gold Brand w/gold pins) 5963 or 5814A. Seems like the CTH comes across a tad brighter than my amp and the GB's are as smooth as it gets. Just something to keep in mind if you see one._

 

DId you build a CTH for yourself olblueeyez? is it possible that the CTH is a tad more detailed in the higher frequencies than your amp?


----------



## adamus

ok, I am rapidly thinking the hypothesis of the heaters causing the noise is correct. 

 6.3v tube = hum
 6.3v tube with large heater current = louder hum
 12.6v tube = very little hum


----------



## adamus

ok, I have created a near silent CTH!

 I changed the small inductor, for a radial inductor, mouted slightly higher on the board to miss the resistors. Its also got a higher rating.

 result.... very enar silence with 12v tubes. I'll try a 6v tube and report back.

 Edit


----------



## sachu

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_ok, I have created a near silent CTH!

 I changed the small inductor, for a radial inductor, mouted slightly higher on the board to miss the resistors. Its also got a higher rating.

 result.... very enar silence with 12v tubes. I'll try a 6v tube and report back.

 Edit_

 

heh..finally!!


----------



## adamus

Its funny, i have built so many amps, done p2p, done a bijou, done a full valve speaker amp p2p, done perfboard.... and the most trouble shooting i have ever had to do is with a CTH, which should be 'stuff and go"!.



 With 6.3v tubes there is still a noticeable hum, much reduced but still noticeable. I'll stick the 8416 i think and be done with it!


----------



## Forte

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_ok, I have created a near silent CTH!

 I changed the small inductor, for a radial inductor, mouted slightly higher on the board to miss the resistors. Its also got a higher rating.
 Edit_

 


 What inductor did you use?


----------



## cfcubed

Wasn't going to post until after some tests which should pin things down, but...
  Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I changed the small inductor, for a radial inductor_

 

Yes, inquiring minds would like to know the value & maybe a pic of its position.

 The small 3uH choke is part of the ripple filter. My research said it could be from 2uH -> 4uH... In the dim & distant past in CTH prototyping, I _think_ I read that raising the coils off the PCB/ground-plane was one approach to reducing noise in the circuit, but I'd have to dig that up. 

 Really looking for a complete solution here, of course. My gut says it has to do w/duty cycle which is only about 20% @ 6.3v vs about 40% @ 12.6v in the sims (see screenshots in a prior post). Reducing Vin raises duty cycle. 

  Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_ < snip >the most trouble shooting i have ever had to do is with a CTH, which should be 'stuff and go"!._

 

Didn't all the prior trouble come down to a mistakenly grounded opamp pin? Was tough to find tho.
 This noise bit may be more of improving the design, physically or electronically, to address a narrow/confined issue it exhibits under certain conditions.


----------



## tacitapproval

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_ok, I have created a near silent CTH!

 I changed the small inductor, for a radial inductor, mouted slightly higher on the board to miss the resistors. Its also got a higher rating.

 result.... very enar silence with 12v tubes. I'll try a 6v tube and report back.

 Edit_

 

Cool news. Raising R18 to 221ohms helped some, but certainly not silent. As others have said, I look forward to hearing the details.


----------



## adamus

6v is still too noisey for my liking. I'll rescope it and take some pics, there is less general noise so it should be clearer.


----------



## wiatrob

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_ok, I have created a near silent CTH!

 I changed the small inductor, for a radial inductor, mouted slightly higher on the board to miss the resistors. Its also got a higher rating.

 result.... very enar silence with 12v tubes. I'll try a 6v tube and report back.

 Edit_

 

Hmm. I will try to swap the inductors in my proto and see if there is any difference. The only inductor that's different on the proof build is L2H - it floats a bit off the ground plane as it's LARGE...

 The CTH is a _tad _more involved than stuff and go, which I attribute to parts density.


----------



## adamus

waitrob - I recieved the bushing and a little gift! many thanks, superb service. Hats off to you sir.


----------



## sachu

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_waitrob - I recieved the bushing and a little gift! many thanks, superb service. Hats off to you sir.
	

	
	
		
		

		
		
	


	


_

 

yeah, true that. I don't know how the sad person does it.


----------



## adamus

double post...


----------



## wiatrob

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_waitrob - I recieved the bushing and a little gift! many thanks, superb service. Hats off to you sir.
	

	
	
		
		

		
		
	


	


_

 

Anytime! Sorry I spaced that bushing... Doh!


----------



## runeight

It does appear that the hum/buzz is related to the draw from the heater supply. This kind of makes sense since the ability of the first filter cap to handle the ripple goes down as the current draw goes up.

 But it also means that the 120Hz hum is getting through the switching regulator. The chokes will have not effect on it because they are so small.

 It could also be a grounding issue, but I don't think this is likely. The ground plane for the heater circuit is totally isolated from the larger ground plane except where it connects at the SG point. So if SG is well grounded, ground currents from the heater supply should not affect the main ground plane.

 IT could also simply be that with more heater current the radiated EM from the switching currents from the heater diodes is larger and makes its way to the tube. 

 The only way to tell the difference would be to make C3H much large and see if that reduces the hum problem. If it does, we know it's buzz leaking through the regulator. If it doesn't then it's EM from the diodes.

 Somehow we missed this issue during prototyping. Don't know how and the boards are basically identical.


----------



## keyid

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_Can you tell us more about the sound of the Siemens tube with the CTH?_

 

Havent done much comparison to the e82cc but the 5418a sounds more refined. Highs seems to extend further and it does not have an enveloping sound as the e82cc. Its more punchy with 5418a and sharper giving the sound more details. It does sound neutral compared to my other tubes which tries to bring out the mids/highs/lows. I do miss some sweetness from the e82cc but when I put back the e82cc it sounded a little muffled/congested in comparison.


----------



## adamus

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_It does appear that the hum/buzz is related to the draw from the heater supply. This kind of makes sense since the ability of the first filter cap to handle the ripple goes down as the current draw goes up.

 But it also means that the 120Hz hum is getting through the switching regulator. The chokes will have not effect on it because they are so small.

 It could also be a grounding issue, but I don't think this is likely. The ground plane for the heater circuit is totally isolated from the larger ground plane except where it connects at the SG point. So if SG is well grounded, ground currents from the heater supply should not affect the main ground plane.

 IT could also simply be that with more heater current the radiated EM from the switching currents from the heater diodes is larger and makes its way to the tube. 

 The only way to tell the difference would be to make C3H much large and see if that reduces the hum problem. If it does, we know it's buzz leaking through the regulator. If it doesn't then it's EM from the diodes.

 Somehow we missed this issue during prototyping. Don't know how and the boards are basically identical._

 

Runeight, I'll scope the heaters today and report back.


----------



## adamus

Just scoped the heaters. There is a lot of 100hz in there, with peaks of 40mv

 but, moving to the output signal, with shorted inputs.... timebase 5ms, and y axis 2mv.


----------



## adamus

alex,

 Given those of us who have hum tend to hear it stonrger in the left channel, does that give any indication of the issue?


----------



## runeight

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_alex,

 Given those of us who have hum tend to hear it stonrger in the left channel, does that give any indication of the issue?_

 

Just looking at the board layout this is the opposite of what one might expect.

 The left channel's components are farther away from the heater and LV supplies than the right channel's. The right components are buried at the edge of the heater and LV supplies. Thus you would expect that if this were radiation the right would have a bigger problem than the left.

 Furthermore, because of the orientation of the tube the traces from the input connector to the right channel grid are longer and have more opportunity for picking up noise.

 OTOH, the left channel is a bit closer to the HV supply but even there the left components no closer to the noisy parts of the HV supply than are the right.

 So I'm thinking that this rules out EM from the diodes and caps.

 Try putting the scope on the B+ and then on the emitters of Q3P and Q4P.


----------



## adamus

ok, i'll give it a go. 

 The noise is very tube dependant. 

 ecc88 = noise
 6922 = no noise (or very very little)
 6n1p = a lot of noise, too noisey to listen too.
 8416 = some noise
 12au7 = no noise (or very very little)


----------



## runeight

Is everyone having similar noise problems or are there some amps that are quiet?


----------



## adamus

not everyone, but enough to potentially not just down to builder error. If i built the kit with a 12au7, I may have never questioned it.... its very quiet, maybe just a hint of white noise. 6n1p is a different matter. 

 my scopes a lot crap so am struggling to get anything meaningful from The b+.
 All i can get is a solid mass of 'noise' spanning about 10mv (maybe just crd noise?). there doesnt apear to be any ground noise of low frequency hum on it.


----------



## zkool448

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_If i built the kit with a 12au7, I may have never questioned it.... its very quiet, maybe just a hint of white noise. 6n1p is a different matter._

 

x2 -- either that or just been spoiled with the SOHA II


----------



## TimJo

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Somehow we missed this issue during prototyping._

 

I know in my case, I didn't notice it until the first time I tried a 6n1p. Now I realize it was probably there all along, but not very obvious or bothersome running 12au7's, as Adamus noted...

  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_It does appear that the hum/buzz is related to the draw from the heater supply. This kind of makes sense since the ability of the first filter cap to handle the ripple goes down as the current draw goes up.

 The only way to tell the difference would be to make C3H much large and see if that reduces the hum problem._

 

I'd be willing to try this... How big can C3H be?


----------



## holland

As big as you can get it as a test (470uF-1000uF), if you've got it on hand. I would think something around 120uF might work, but try big first. I would also look at C1H and C2H. If you've got them, try 220uF (for those going after the 1A version) after C3H though.


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_ Thus you would expect that if this were radiation the right would have a bigger problem than the left._

 

None of this will probably help:

 I never noticed the noise during prototyping. Nor did any of the rest of th eproto team I think. I have always heard some white noise in both channels at full volume with no inpuut - it's a _tube _amp! 
	

	
	
		
		

		
		
	


	




 It seems to be tube and current dependent - my 6H30 is the loudest. HOWEVER, I didn't seem to notice it before.

 To fuel the confusion - what noise I can hear is more prevalent in the right channel. (Is that Runeight syaing @*&#%@$%%*! 
	

	
	
		
		

		
		
	


	




)

 I also replaced C3H with 220uF - seems to reduce noise at 6V. *EDIT *- missed the C3H suggestion, I can make it even bigger...

 No one has actually done CFCubed's suggested battery heater supply. I may try this in the afternoon, gotta see what's in the battery drawer. 

 Adamus - did I miss what value you changed L1H to?


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I never noticed the noise during prototyping. Nor did any of the rest of th eproto team I think. I have always heard some white noise in both channels at full volume with no inpuut - it's a tube amp! 
	

	
	
		
		

		
		
	


	


_

 

I've never noticed it on mine using my high sensitivity low-Z headphones (D2000) on the 2 that I have built. I have, however, never tried IEMs with this. 
	

	
	
		
		

		
		
	


	




 For those hearing the hum, what are your output resistor values? I've got 100.


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I also replaced C3H with 220uF - seems to reduce noise at 6V. *EDIT *- missed the C3H suggestion, I can make it even bigger..._

 

Try different values and report back.

 If you've got a scope it would help. If not, a DMM should be able to pick up the ripple to a certain degree. If it is 40mV or so, you'll see it.

 If you check it on the input to the reg, it'll be larger, and you can view the impact on the input vs output ripple. For high heater versions, you'll want larger C1H and C2H as well. 100uF isn't enough. I'm going to go with 220uF for 1A, according to the datasheet.


----------



## runeight

No, I wasn't thinking of builder error, but I was wondering if we can find a way to compare the amps that are quiet with the ones that have noise to see if we can discern any differences.

 These might be caps, enclosure, wiring, or other component choices.

 If we can find something then we can alert everyone to what might be a build issue. If we can't find any real difference between noisy amps and quiet ones then this implies that it is external factors of some kind.

 If you all would be willing to answer a few questions, perhaps we can get a sample of data.

 1. Is your amp quiet or noisy
 2. What enclosure are you using
 3. What coupling caps are you using
 4. Where have you located the off board components and their wiring
 5. Is your pot grounded
 6. Have you done anything else unique to your build
 7. What headphones

 Edit: Added Q number 7

 Thanks


----------



## adamus

I'll start

 1) noisey with most tubes apart from 12au7 and 5693
 2) small hammond
 3)bom, 1uf box
 4) power and heater switch at the rear, pot and mini jacks at the front. RK09 pot.
 5) tried both, no difference
 6) no.
 7)HD650's (little noise), Cx300 (IEM) louder noise.


----------



## holland

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_1. Is your amp quiet or noisy
 2. What enclosure are you using
 3. What coupling caps are you using
 4. Where have you located the off board components and their wiring
 5. Is your pot grounded
 6. Have you done anything else unique to your build
 7. What headphones_

 

1) quiet
 2) Context Engineering 3008 and Hammond 1455K1601
 3) Context Engineering - AVX caps. Hammond - Wima
 4) Board is mounted in the upper slots. Large caps (taller than tube socket) underneath. Power and heater switches underneath and to the rear. Fuse, underneath between power and heater switches. All wiring is underneath. Wiring (if looking at Ric Lee's diagram) input is upper right, Output is lower left. Wiring runs along the upper wall, bends at the face plate to the pot.

 LED on the front panel, on diagram, bottom left.

 Proto, heater reg and 24V reg underneath.
 Production, heater reg and 24V reg on top.

 5) Yes
 6) Proto has output resistors on the jack instead of in the servo loop.
 7) tested with Denon D2000, Beyer DT440, Beyer DT990.

 Tubes used.

 6N1P
 6N6P
 12AU7 and variants
 6922 and variants


----------



## sachu

Two builds with the longer case: One proto one production

 1) No
 2) Large hammond
 3) BOM
 4) 
 ->production one with mini jacks has i/ps and o/ps in the front along with the pot.
 -> proto one has RCA jacks at the back and a full size neutril on the headphone out up front along with the pot.

 ->power and heater switch for both at the rear.
 5) Yes, on both
 6) No.
 7) Fostex T50RP, Yamaha Hp2 orthos


 Tubes used were, 6DJ8, 6N1P, 12BH7, 5963.

 My other production build went to smeggy and his is in a plastic case and is not reporting any noise in his as well.


----------



## wiatrob

I don't have the scope with me, but I do have a good meter. I'll look for ripple changes before I go changing things willy-nilly.

 I'll get to the questionnaire in a moment - BUT:

 The 6H30 is the loudest - but it is *DEAD *silent with my 150R orthos (YH-3s). Blacker than Black...All the 6 volt tubes are. 

*EDIT*: I used the proto build at work mostly with the YH-3s early on in the proto phase...


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_1. Is your amp quiet or noisy
 2. What enclosure are you using
 3. What coupling caps are you using
 4. Where have you located the off board components and their wiring
 5. Is your pot grounded
 6. Have you done anything else unique to your build
 7. What headphones_

 

For the Proto:

 1. Slight noise (more with 6V tubes, *EDIT*: Unnoticeable with some 12V {5963, 5814WA, clear top} - very low with 12BH7)
 2. Hammond 1202 Wooden Ends
 3. 100V Wimas
 4. Standard front placement of jacks and BoM pot. Wires gathered with zip tie 1" between board and panel. Shielded wire from input to pot.
 5: yes and no, grounding doesn't affect hum
 6: switching inductors changed to 1A rating. Slight decrease in noise from stock. Cap mods in progress.
 7: Output resistors 56R 

 Phones:
 Senn PX100
 Senn HD650
 Grado RS-1
 Yama YH-3 (amp is silent with ALL tubes with these phones)


----------



## zkool448

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_If you all would be willing to answer a few questions, perhaps we can get a sample of data.
 1. Is your amp quiet or noisy
 2. What enclosure are you using
 3. What coupling caps are you using
 4. Where have you located the off board components and their wiring
 5. Is your pot grounded
 6. Have you done anything else unique to your build
 7. What headphones_

 

1. 12AU7, quiet with a very faint hum (unnoticeable), with 6N1P noise/hum level is increased.
 2. nekid right now
 3. sprucecanyon bom (i.e. 100% stock)
 4. air wired everywhere (uncased), no effect moving wires around 
 5. yes, hookup wire to SG
 6. unshielded wires, soldered to bottom instead of top of pcb
 7. mdr-xb700, beyer dt880


----------



## wiatrob

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Try different values and report back.

 If you've got a scope it would help. If not, a DMM should be able to pick up the ripple to a certain degree. If it is 40mV or so, you'll see it._

 


 with the 220u, I get 5.5mV at pin 2 of the lm2595 at 6.3V setting

 However, should there be AC on the OUTPUT of the switching reg (measured from SG)? I'm measuring ~12 and 14VAC (6.3/12.6V Heater) on pin 1 of the 2595...


----------



## adamus

that could be a dmm error. Mine does that when measuring ac with highish dc.


----------



## keyid

1. Is your amp quiet or noisy

 12au7 near silent especially leaving it on for a while
 6n19 annoying hum 

 2. What enclosure are you using

 longer version of the default case

 3. What coupling caps are you using

 Russian Teflon FT3, air wired. The wire is covered with copper tubing, this cut majority of the hum with 12au7 as the exposed wire was picking up signals.

 4. Where have you located the off board components and their wiring

 input / output run from under the board to the front. Planning to cover them in copper tubing soon.

 5. Is your pot grounded

 no, hum is still present with or without. 

 6. Have you done anything else unique to your build

 used shielded tube adapters, used stepped pot, c4 caps is outside of the case, the reg is attached to the case for better cooling solution, 

 7. What headphones

 hd600
 yh-1
 k501
 koss pro/4aa


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_However, should there be AC on the OUTPUT of the switching reg (measured from SG)? I'm measuring ~12 and 14VAC (6.3/12.6V Heater) on pin 1 of the 2595..._

 

There will be some, but after the post-reg filter, it should be very small. That is your ripple voltage (AC remnants), and it should be at 2x your AC Hz. Rectified AC is @ 120Hz in 60Hz countries (like US) or 100Hz in other places with 50Hz AC. Your DMM will likely be in the error range at that point. You'll need a scope to get an accurate reading and if it's in the uV range it would be best to amplify it (with something like Tangent's LNMP).

 However, if you're getting 40mV (like what adamus reported) it's well within the range of a good DMM and will show as that's a gigantic post reg filter ripple.


----------



## wiatrob

Hmm, I'm buying the DMM error on the output of the reg. Measured after L1H, less than a mV (with Fluke 189). I'll try to bring a scope home tomorrow.


----------



## runeight

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_There will be some, but after the post-reg filter, it should be very small. That is your ripple voltage (AC remnants), and it should be at 2x your AC Hz. Rectified AC is @ 120Hz in 60Hz countries (like US) or 100Hz in other places with 50Hz AC. Your DMM will likely be in the error range at that point. You'll need a scope to get an accurate reading and if it's in the uV range it would be best to amplify it (with something like Tangent's LNMP).

 However, if you're getting 40mV (like what adamus reported) it's well within the range of a good DMM and will show as that's a gigantic post reg filter ripple._

 

Maybe. If this were a power rail 40mV would be huge ripple and would buzz everything.

 But this is a heater line. Amps are dead quiet with 12.6/6.3VAC on the heaters where the ripple voltage peaks are 9V and 17V. 

 I think that 100Hz/40mV at pin 4 of the tube will not find its way into anything.

 Now, if this buzz is making its way to the ground plane or somewhere else then it is definitely a problem. If it is, we haven't found out how yet.


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Hmm, I'm buying the DMM error on the output of the reg. Measured after L1H, less than a mV (with Fluke 189). I'll try to bring a scope home tomorrow._

 

1mV, wouldn't worry about it...

  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Maybe. If this were a power rail 40mV would be huge ripple and would buzz everything.

 But this is a heater line. Amps are dead quiet with 12.6/6.3VAC on the heaters where the ripple voltage peaks are 9V and 17V. 

 I think that 100Hz/40mV at pin 4 of the tube will not find its way into anything.

 Now, if this buzz is making its way to the ground plane or somewhere else then it is definitely a problem. If it is, we haven't found out how yet._

 

You're right, of course, that it probably doesn't matter on the heater line. 
	

	
	
		
		

		
			





 I've got very limited experience with tubes, and just finished my Bijou (which is full on AC as you're aware), and it's dead silent with my D2000.

 I have my doubts, as well, that it's ground contamination.


----------



## wiatrob

Hmm. *

 Don't mess with anything that is working. 

*Well, I did something to make the hum worse, so if I can figure that out, maybe it's a clue. Paralleled two 100u's to C1,2H - no change. Upped L1H to 6,6, louder. Restored caps and L1H to original value, still loud, but L1h is tacked under the board.

 EDIT: Found out where this louder hum is coming from. ICP dead again - outputting 27V. This happened to me early on in the proto phase with the exact same result. I'll replace it tomorrow...


----------



## wiatrob

Quick followup. Back to where I started. 12V tubes are silent, very slight noise on 6V tubes (slightly louder with the 6H30). @4-5mVAC at pin 4.

 Might everyone with a very noticeable hum measure output of ICP and make sure it's in spec?


----------



## cfcubed

Just an FYI: My patient is on the operating table w/DMM + scope attached. Plan to get into this tonight.

 BTW, wife's B-day was last Friday, had lots Saturday & Sunday was Mothers Day. Not able to get into this, let wife know about the flurry of posts happening about "my" part of the CTH design.... *She asked  "Don't these guys have mothers?"*. A good question, I had to admit, for which I had no answer


----------



## wiatrob

Dude, we've got Moms! Just no wives with kids 
	

	
	
		
		

		
		
	


	




 My build is back to working - it's got 1000u on C3H and 200u at C1/2H (_and it somehow made it back into the case_)- without that much of a change in ripple at pin4 of the tube. Methinks the heater design was right on. 

 But what do I know! I'll grab a scope at work today time permitting...


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Dude, we've got Moms! Just no wives with kids 
	

	
	
		
		

		
		
	


	


_

 

He he. You should know my sense of humor by now
	

	
	
		
		

		
		
	


	




 A bit caustic. Did think it was funny for her to ask that tho
	

	
	
		
		

		
		
	


	




 WRT the heater design - Like I do my real job, software development, I assume bugs are mine until proven otherwise. In this case, I'll only be convinced the heater circuit plays no role in this issue after my disabled switcher/battery heater test tonight. 
 Wouldn't be surprised find the heater circuit is involved, either through its EMI or its reception of EMI. Again, things are exceedingly tight on the CTH PCB, esp. vs my P2P POC:


 
 that had input stage a good 4 inches or so from PS. And more space between SM heater portion (bottom) and HV section (top).

 Edit: BTW, my suspicion as to why this did not really come up during 1st 10-PCB proto run is that 12au7s were more commonly used, as maybe higher-Z/less efficient cans. Most were also enamored w/the amps sound enough to possibly overlook this.


----------



## MrSlim

Alex, here's the data on my prototype.

 1. Is your amp quiet or noisy: No, very quiet with a 6dj8 or 12BH7a
 (there was some hum until I replaced the unshielded input wires with shielded)

 2. What enclosure are you using: Hammond 1602 with a perforated top cover

 3. What coupling caps are you using: Wima ( MKIV's ?) 

 4. Where have you located the off board components and their wiring
 RCA's in, 1/4 inch out and Alps RK27 all mounted on the front panel. RCA's to RK27 to board using shielded cable. Wires out to the 1/4 jack are unshielded. 

 5. Is your pot grounded: No

 6. Have you done anything else unique to your build: No

 7. What headphones: AKG K601


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_He he. You should know my sense of humor by now
	

	
	
		
		

		
		
	


	




 A bit caustic. Did think it was funny for her to ask that tho
	

	
	
		
		

		
		
	


	


_

 

Make sure she knows National Hybrid Headphone Amp Day is coming up! 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_WRT the heater design - Like I do my real job, software development, I assume bugs are mine until proven otherwise. In this case, I'll only be convinced the heater circuit plays no role in this issue after my disabled switcher/battery heater test tonight._

 

That's a refreshing change from the attitude of some of the developers I work with 
	

	
	
		
		

		
		
	


	




 I hadn't realized the POC build was quite so spaced out. That might explain the Delta between battery/switcher. Look forward to your results - and saving me from doing it. I lifted about 6 traces goofing around yesterday.


----------



## runeight

I'm not convinced yet that the heater supply is at fault. That is, I'm not sure that there is anything wrong with its design. It could be, as you guys have noted, simply proximity issues or it could be some interaction that was not caught during prototyping.


----------



## adamus

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Hmm. *

 Don't mess with anything that is working. 

*
 EDIT: Found out where this louder hum is coming from. ICP dead again - outputting 27V. This happened to me early on in the proto phase with the exact same result. I'll replace it tomorrow..._

 

Checked mine and its dead on 24v. 

 I also checked the heater supply again on the scope, looks good enough, and like alex says, in the bijou we are using ac, so the odd millvolt shouldnt have an impact.


----------



## zkool448

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_5. Is your pot grounded: No_

 

MrSlim, can you explain why some builds need the pot grounded, and some do not (as in NO hum when you touch the knob)?


----------



## adamus

check the emitters of q4p and q3p and the power is perfectly clean. 

 changed all input wiring to shielded wire.

 checked the 24v power rail, again perfectly clean. 


 noise is present with pot all the way down....

 looks like this has to be noise on the ground.


----------



## runeight

Been having a background conversation with Adamus as he noted and he has been taking some measurements. I had a theory of a potential problem but have discarded it after thinking it through.

 What adamus has done is to scope all of the rail voltages. They are all squeaky clean except for the 40mV on the heater. He has also placed a grounded tube shield on the tube. Nothing changes.

 So, with grids grounded, tube shield on, and clean voltages the only other possible candidate is a ground problem.

 This might take a little thought . . .


----------



## adamus

ok, i think we have a breakthrough. 

 I cut the pins off a 6n1p that went bad, only pins 4 and 5 remain. 

 with the heaters on there is noise, pulling the tube out and the noise disappears.


----------



## runeight

Really appreciate the tests that Adamus has been running and this is a real breakthrough on this problem.

 What is says is that the noise appears when the heater supply is loaded whether the tube is there or not. So EM radiation or other tube noise is not the issue.

 This means that loading the heater supply is affecting the other supplies somehow. 

 We are working on it . . .


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_... He has also placed a grounded tube shield on the tube. .._

 

Forgot to report I also tried this last night - same result. With my upgraded caps, i only have 7-9mV on the heaters.

 Looking forward to...something! 
	

	
	
		
		

		
			





 Let me know if you need another guinea pig.


----------



## runeight

Why yes, while Adamus is sleeping ...

 What we want to investigate is what happens to the LV supply when the heaters are turned on and off.

 If you have a 22R 5W resistor you can stick this into pins 4&5. To simulate a 6H30 use 10R. Both at the 6.3V setting.

 Or you can do what Adamus did and take a bad tube and cut all of the pins off except for 4&5.

 Do you also hear a change in noise when the heater circuit is loaded and when it is not? If so . . .

 If you have a scope we need to see what the voltage looks like both before and after the regulator. DC and AC components.

 Since the tube is not in the circuit it can't be the B+ supply. It can only be the LV supply or a grounding issue.


----------



## cfcubed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_ok, i think we have a breakthrough. 
 I cut the pins off a 6n1p that went bad, only pins 4 and 5 remain. 
 with the heaters on there is noise, pulling the tube out and the noise disappears._

 

*My testing does not support the above* unless qualifiers are added ( 5mv noise w/loaded heater and no tube, upto 30mv noise w/tube).

 Here's what I did:
Shorted R18s (output resistors) to hear noise better. W/6BZ7 noise is very apparent now w/D2000s.
Using a "bad" 6BZ7, cut off all but pins 4/5 and tested. Noise was much less audible & only averaged 5mv on my scope.
Decided to really load switcher. Used 10R 10W resistor across heater pins. This draws about 600ma @ 6.3v. Same results as tube w/pins cut-off - Noise much, much lower. In fact, not above ambient noise level on my scope, about 5mv, but of different content than ambient noise.

 So although heater circuit plays a role in this noise, I do not believe it comes down to it simply supplying load current/wattage. 

 If you do resistor load tests watch out you do not exceed 800ma draw. E.g. at one point I used a 15R resistor in load testing. At 6.3v it drew 360ma, at 12.6v it draw about 800ma & the heater circuit made an audible buzzing sound.

 So more research to do. This may wind up being 1) switcher causing ground contamination (isolate its ground/ground plane?), 2) switcher causing back-EMI into common A/C supply, 3) a bit of both. Note we are not employing a line-in EMI filter here (typically chokes & capacitors) and it looks like that might require a dedicated 1" X 2" PCB area that we do not have.


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Why yes, while Adamus is sleeping ...

 What we want to investigate is what happens to the LV supply when the heaters are turned on and off._

 

Sorry i missed this, went to sleepy...


 Let's see where we're at tonight, scope is on the bench. I may need some help on using it 
	

	
	
		
		

		
		
	


	




 (Where to attach the ground lead SG or closer to the measurement point (Pin 4?)


----------



## cfcubed

Just an FYI: I'm doing my noise measurements at the amp's outputs... This is what really counts as this is what we hear. Again, think about shorting R18s to make the noise more audible.

 I'll be researching more tonight & tomorrow as well. And since the only way I can get significant noise to come out of the amp is with a 6.3v heated tube (with all its pins), that's the way I'll be testing.

 I'll be looking to see about isolating the switcher's ground plane (incls pulling L1H away from main amp's plane), maybe raising both heater's coils well off the PCB, maybe pulling D1H + D3H & feeding switcher from another 24V rectified supply, maybe fooling around with physical shielding for switcher as a whole (bent up sheet metal).

 All of this to find if noise is made up of 1) (common) ground plane contamination, 2) general EMI broadcasting, 3) backfeed EMI into common A/C (that HV & LV are not filtering). May be some combo. But what do I know
	

	
	
		
		

		
		
	


	




 So others can pursue other ideas.

_Edit: A little note WRT my "we are not employing a line-in EMI filter here " for SM circuit. I don't think one is needed for backfeed EMI to mains/AC as the wallwart is providing this isolation. Only a consideration if backfeed EMI is found the primary cause of our noise._


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I'll be looking to see about isolating the switcher's ground plane (incls pulling L1H away from main amp's plane),_

 

My proto currently has both coils mounted up at least 1/2" to 3/4", That's the only way the 1 amp versions fit. didn't notice a differenc in noise level, but perhaps some combo. Listening now with my Tung Sol 12Au7, nice and quiet with the RS-1s . but we know that


----------



## adamus

hows the testing going chaps? I am all tested out. I find spikes on the 24v line with a tube in that i dont find without. 

 If anyone has a scope, please have a go at confirming my results. 

 Cheers


----------



## runeight

Remember that the heater ground plane is already isolated from the main ground plain. They only contact at one point near the SG. If the SG is well grounded no heater ground noise should sneak over to the main ground plane.

 Look carefully at your board ground planes and you will see this.


----------



## cfcubed

I believe heater's L1H is outside the heater ground plane, but don't think this matters anyway.

 With disabled heater circuit & battery heater no hum is heard w/6.3v heated tube. A good deal of hiss/white noise is heard w/R18s shorted, battery heater & D2000s. But this is all about the hum style of noise.

 So somehow the heater circuit is causing this issue. More research is needed. Once again, issue is largely limited to use of non-12AU7s & sensitive cans & is heard when there is no input signal.


----------



## wiatrob

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_hows the testing going chaps? I am all tested out. I find spikes on the 24v line with a tube in that i dont find without. 

 If anyone has a scope, please have a go at confirming my results. 

 Cheers_

 


 Scopes are Kewl! 
	

	
	
		
		

		
		
	


	




 Ok, Alex, I'll systematically respond to your questions - but I tried this first. As reproted my AC mV on the Heater supply are ~5 (with all my extra capacitance)

 Phones 32ohm PX100 100R R18

 AC mV on 24V supply (probe on Vout, SG):
 DC is right at 24V

 12V No Tube .3-2.0mV very very slight Hum must press phones to head)
 12V 12AU7 .3-2.0mV Very Slight Hum

 6V No Tube .3-2.0mV very very slight Hum

 6V 6BQ7 heater pins only 2.8-3.x mV very very slight Hum

 6V 6H23 1.7-2.3mV slight hum

 6V 6H30 6-12mV slight hum

 Hum is mostly in right ear. 

 Any help, or adding to the confusion?

*EDIT*: Even with the 6H30 hum is very low tonight.


----------



## wiatrob

Even with a 6N1P is very slight with the px100, have to press senn 650s to hear any hum at all. I swear this was noisier Sunday night.

 Cosmic Rays? 
	

	
	
		
		

		
		
	


	




 I'm gonna case her back up and see...


----------



## cfcubed

With some certainty, from further testing, I've drawn these conclusions:
*Some tubes will hum to some degree, at least in CTH, regardless of heater supply implementation and regardless of their heater draw.*
*The primary cause of hum/noise at issue here is backfeed/line-in A/C EMI by switcher to common A/C supply line.*
Here's what I did:
Disabled on-board SM heater circuit in my CTH. Done by removal of D1H & D3H (LM2595 DC in) & removal of L1H (as well as its unraveling destruction
	

	
	
		
		

		
			



Ran external wire for CTH heater pins (#4 & #5). Re-cased CTH to move it away from assorted bench EMI (fluorescent lights, etc)
With 4 D cell heater supply 6922 has NO hum. 6BZ7 has faint hum.
Used P2P POC heater circuit to power tube heater (same components as on-board CTH heater)... When CTH A/C + outboard SM heater circuit are fed from same A/C supply get good deal of hum. Feeding CTH & outboard SM heater circuit from separate A/C supplies (adapters) - very, very faint hum... Not easily distinguishable from ever-present low-level hiss/white-noise amp exhibits (even w/battery heater supply, w/R18s shorted & D2000s)

 Note: While "Feeding CTH & outboard SM heater circuit from separate A/C supplies (adapters) - very, very faint hum..." I carefully waved the outboard P2P switcher supply very close to the CTH PCB & very close to the tube & this did not elicit noise, so I no longer suspect general EMI radiation from switcher as cause of noise. Ground (plane) contamination is also unlikely the cause (based on this test & wiatrob's raised switcher coil results).


 My goal now is to get the hum level at or below the ever-present hiss level, IOW not easily discernible from it, for tubes that have no hum w/battery heater supply - e.g. my Mullard 6922). 
 I've a few line-in EMI filtering components in my parts graveyard to experiment with (to inject between outboard switcher diode bridge & its CTH-shared A/C supply/adapter). And that's what I'll be doing as time allows.


----------



## adamus

I have to say, i dont think i cn live with mine with the level of hum i am experiencing. now i have noticed it...... i listen to it. Most people may not even notice it but for me i cant stop listening to it. 

 So, i may recase the amp, and build a 6.3v heater circuit for it, running from its own supply. I'll buy a small transformer, and spec it for an amp so i can run most tubes. 

 I am going to hold tight for a bit though, with the amount of brains on this problem, someone will find a solution i am sure.


----------



## cfcubed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I have to say, i dont think i cn live with mine with the level of hum i am experiencing. now i have noticed it...... i listen to it. Most people may not even notice it but for me i cant stop listening to it. _

 

I react this way to annoyances too, so know where you are coming from... E.g. when we had our 25yrold MBR bathroom renovated, it came out gorgeous but I couldn't stand it until the drip from the shower head was fixed. 
	

	
	
		
		

		
		
	


	



  Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I am going to hold tight for a bit though, with the amount of brains on this problem, someone will find a solution i am sure._

 

Best plan of action I think. I, for one, am not near giving up on this one.

 BTW, AFAIK w/o SM heater circuit of some kind the CTH could not have happened, at least not near its target form-factor. Think the (linear) 24V reg gets hot throwing off 8 volts or so in heat imagine trying to throw off 26 volts linearly to get 6V heater


----------



## adamus

for sure, we wont give up until something is sorted, and with the 12au7 its really not too bad.


----------



## wiatrob

Here's a wacky thing. The audible noise when I was doing scope tests last night was lower than I remembered, even with the 6H30...

 I just got a 6CG7 clear top here an it sounds fine - I have my hands cupped hard over the cups of my RS-1s and I don't hear any hum...none. If I flick the tube I can hear the ping, but it's really silent - even though the 'scope indicated i was seeing similar AC spikes as adamus (lesser intensity as I have a bunch more capacitance on my heater supply). 

 I am going to curl up in a quite corner of the garage tonight and do some purely subjective tests...


----------



## cfcubed

wiatrob - Yes, you raised C3H as I recall. And as my testing indicates, primary noise/hum is backfeed from switcher, makes sense that raising that cap's value had an effect.

 When I get a chance I'm going to try:
raising C3H as you did. Perhaps 220uF -> 470uf. Perhaps adding a low uF cap as a sort of snubber.
introducing resistance prior to switcher to lighten its duties.
investigate EMI filtering (chokes, etc) between switcher & common A/C supply.
In that order.


----------



## nux

Just thinking out loud, would a ripple on B+ cause hum? Has anyone looked at the B+ waveform loaded/unloaded? Of course, make sure your oscilloscope can handle ~100V inputs (or AC couple it).

 Is VG stable compared to SG?

 And is it recommended that SG point be connected to anything? I've read that people haven't noticed a change when grounding the pot. Is it worth grounding the case to SG if you are using plastic ends? I just ask this as I get noticeable hum when I am using my y1 DAC with a DC plugpack, although I know this is a seperate issue, but not sure how to resolve it.


----------



## wiatrob

Quote:


  Originally Posted by *nux* /img/forum/go_quote.gif 
_And is it recommended that SG point be connected to anything? I've read that people haven't noticed a change when grounding the pot. Is it worth grounding the case to SG if you are using plastic ends? I just ask this as I get noticeable hum when I am using my y1 DAC with a DC plugpack, although I know this is a seperate issue, but not sure how to resolve it._

 


 SG should be grounded to the case: http://www.cavalliaudio.com/cth/imag...ingDiagram.jpg

 The y1 issue may be a ground loop?


----------



## wiatrob

Well, it ain't scientific, but I did some 'normal' listening tests this eve - with the Senn 600s, relaxing in the quietest part of the house. 

 All 6.3V:

 6CG7 Clear top - as reported today, silent. Very nice tube too.

 6922 BB Hum in right, low but noticeable, varied by tube.

 6H6P - noisiest, low but noticeable. In LEFT

 6H30 barely audible (have to press phones to head), not distracting

 6N1P Sovtek - silent(?!)

 6H23 Reflektor - Hum in right low but distracting

 Could triode imbalance play a factor? Is everyone else hearing this in the left ch only?


 Raising the value of C3H did lessen the ripple. I have a sideways 1000u in heatshrink wedged in there now - so my amp is not really like the others anymore. I did get a 470u to fit nicely with some bent leads.


----------



## smeggy

holy crap, I just got a siemens E82CC in the mail. It's tiny and sounds spectacular, not even warmed up fully yet and it kicks the previous Sylvania toob in the nads 
	

	
	
		
		

		
		
	


	




 This amp just keeps getting better... I'm in love 
	

	
	
		
		

		
		
	


	




 Mmmm, bassy, sparkly, smooth, crisp and engaging all at once.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_holy crap, I just got a siemens E82CC in the mail. It's tiny and sounds spectacular, not even warmed up fully yet and it kicks the previous Sylvania toob in the nads 
	

	
	
		
		

		
		
	


	




 This amp just keeps getting better... I'm in love 
	

	
	
		
		

		
		
	


	




 Mmmm, bassy, sparkly, smooth, crisp and engaging all at once._

 

I just got a Siemens for my EF1, but I may be trading the EF! away. Was gonna sell the new shrink-wrapped tube, but now I wonder if I should save it for a rainy day.


----------



## smeggy

I think you should sell it to me cheap very quickly before changing your mind... it's the right thing to do


----------



## HeadphoneAddict

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I think you should sell it to me cheap very quickly before changing your mind... it's the right thing to do 
	

	
	
		
		

		
		
	


	


_

 

But what if I get a CTH? I probably need something to use my Mullard long plate and shirt plate, although the pair of Amperex Bugle Boys might be staying with Blutarsky. I did post in the EF1 review thread that I would take $40 shipped, then started to think it might be a mistake. The plan was that my ALO Amphora was to replace my EF1 and other compact amps.

 A true addict will buy an amp just to fit the tubes that he already has...


----------



## smeggy

You don't want a CTH, rubbishy little thing..


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_ < snip >
 This amp just keeps getting better... I'm in love 
	

	
	
		
		

		
		
	


	



 Mmmm, bassy, sparkly, smooth, crisp and engaging all at once._

 

Nice to hear the love, which I know is out there, while focusing on the tiny imperfection
	

	
	
		
		

		
		
	


	



 Right now its like I'm using a magnifying glass on Cindy Crawford's mole... Focusing on that & trying to "fix" it.. So its nice to be reminded of the big picture
	

	
	
		
		

		
		
	


	




 Have to credit others for this *but adding 330uf to C3H looks to be enough to virtually eliminate the noise/hum contributed by SM heater circuit.*

 Adding more than 330uf yields no perceivable benefit - adding less than 330uf does not get full benefit. For 6.3v 600ma load at least.

*My bet is that *if* hum is noticeable for a tube with 330uf added to C3H, that hum would be noticeable w/CTH heater circuit disabled & use of battery supply for heater. * And any such hum may just be due to A/C proximity in CTH.... Perhaps unavoidable without drastic measures (mechanical shielding of A/C area incl all diodes?)

 Here's scoping of A/C supply:





 Left: clean A/C as from adapter w/no load of any kind.
 Middle: A/C supply with heater circuit attached supplying 6.3V 600ma load.
 Right: A/C supply with heater circuit attached supplying 6.3V 600ma load *with 330uf cap in parallel w/stock C3H*

_Edit: I don't think we'll derive any audible benefit by further "cleaning" switcher's backfeed beyond raising C3H to 330uf, at least for stock target CTH heater loads. _

 Hunch is that *removing 47uf C3H & somehow fitting 330uf (35v) worth of capacitance there will satisfy when 100R or greater R18s are used.* 100R->150R R18s are needed anyway to give vol pot usable range & to mask OB hiss/white noise.

 Please use *a low-impedance 330uF cap rated @ 35V or better & lead-length as short as possible.*

_Edit: I'll be boxing up my larger CTH w/onboard heater circuit re-enabled & 330uF 35V low impedance cap C3H to complete validation of this suggestion._


----------



## holland

Thanks for the hard work cfcubed, I think I have some 1000uF/35V in the closet.  Any measurements of post switcher and if post switching affects anything? Some of us are going to start chasing a 1A version, and according to the spec sheet using 220uF C2H would be advisable. I was wondering how bad it is to not follow that, though if I add 220uF to C2H, ~180uF would go to C1H also. I would like DC as smooth as possible just to be DC.

 I could scope it too, but I've been pulling some long days these past few weeks and amp building is not what I want to do when I have 1 hour to eat before sleeping.


----------



## cfcubed

holland - based on my battery vs SM heater testing, which someone could confirm if they wish, *there should be no audible benefits for stock heater loads from raising C1H or C2H*, only raising C3H to 330uF -> 470uF range.

 Keep in mind though that I use D2000s are fairly sensitive/efficient to make these judgments. And these suggestions w/those cans *should* bring hum/noise down to the unavoidable(?) hiss/white noise level present w/battery heater. I'll find this out for my CTH by tomorrow AM EST.

 But to support higher than, say 4W of heater load (6.3V / 630ma & 12.6V / 310ma), I'd consider raising both C1H & C2H to 180uf or so... As well as C3H to 470uF or so. *Low impedance caps are a must for all these *I think, based on my scoping & switcher spec sheet.

 Again my bet is there is likely no further audible benefits to be gleaned from "improving" heater circuit beyond the above suggestions. I'd look to general A/C shielding for entire CTH PCB A/C area for any further noise/hum reduction. And this is a tube amp folks


----------



## Forte

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Please use a low-impedance 330uF cap rated @ 35V or better & lead-length as short as possible._

 

Thanks for following through with this Chris.

 Is 35v the absolute minimum rating we can use? I have 470uf 25v here which would fit flush to board(8mm dia) otherwise the 35v caps I have would have to be mounted off board with longer leads.


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Is 35v the absolute minimum rating we can use? _

 

Yes, I'm measuring 29V or so across existing C3H leads. A 25V cap might last a while tho.

 Know you are doing this, but consider removing existing C3H & putting cap there OR mounting below PCB if using non-std case that supports this.

 Again, will do this to my CTH & boxup within 24hrs but would like confirmation of this "fix" w/tubes supported by stock CTH.


----------



## Forte

Will give the 25v caps a miss then, I have some 35v caps, will see if I can squeeze them in there as best I can. I put in a 100uf cap this morning and the hum definitely reduced even with R18 at 47R.


----------



## Forte

Have just put in a 35v 470uf Panasonic FM cap in and noise seems to be gone.
	

	
	
		
		

		
		
	


	




 The amp is still out of the case and the pot is not currently grounded but seems to be all good. 

 The cap is a tight fit(10mm diameter) and sits about 5mm off the board, but it is in. My build used the original proto BoM with the larger C5P cap, the newer smaller cap used on the production board should give more room.

 Listening with a 6n1p , have a couple of tubes which have been more noisy (6h23, 6bq7a), will try these in the morning as well as listening with some more sensitive headphones.


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Have just put in a 35v 470uf Panasonic FM cap in and noise seems to be gone.
	

	
	
		
		

		
		
	


	




 < snip >_

 

Excellent. 
  Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Listening with a 6n1p , have a couple of tubes which have been more noisy (6h23, 6bq7a), will try these in the morning as well as listening with some more sensitive headphones._

 

Sounds good. WRT 6bq7a & noisy tubes in general, consider what I found in testing _"With 4 D cell heater supply 6922 has NO hum. 6BZ7 has faint hum."_ That with R18s shorted tho. 
 Going further, think we'd need to bark up another tree. Perhaps better then to just write off a few of the dozen or so varieties of tubes that work in the amp (at least when used w/sensitive cans).


----------



## adamus

just tried it..... and the noise is dramatically reduced. I can still here a bit, but its substantially quieter. I'll dig out a 6n1p again and report back.


----------



## wiatrob

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Will give the 25v caps a miss then, I have some 35v caps, will see if I can squeeze them in there as best I can. I put in a 100uf cap this morning and the hum definitely reduced even with R18 at 47R._

 

Mine's a proto board with the smaller cap, so I scooted C5P over a bit and got a 470 pretty nicely (and I think it was a 63V)...


----------



## smeggy

wow, that was quick. Nice job all!


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Have to credit others for this *but adding 330uf to C3H looks to be enough to virtually eliminate the noise/hum contributed by SM heater circuit.*_

 

I think it was the first suggestion Alex made 
	

	
	
		
		

		
		
	


	




 We should look for a drop in substitute for the BoM (as soon as Alex blesses it...) There should be some tall skinny Nichicon models that would work...


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_But what if I get a CTH?_

 


 Hmmm, what if you do? I keep thinking about a special HeadphoneAddict Edition.


----------



## zkool448

It's nice to know even a barely perceptible hum can still be reduced even more is definitely a big plus! 
	

	
	
		
		

		
		
	


	




 Thanks for all your hard work guys.


----------



## adamus

I am still hearing too much noise for my liking, but i have horribly long leads on the 'too big' cap. I'll try and source somethihg that fits.


----------



## cfcubed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I am still hearing too much noise for my liking, but i have horribly long leads on the 'too big' cap. I'll try and source somethihg that fits._

 

It is boxed up? I had to box & move everything to an EMI-quite area of the house to conduct my SM heater vs battery heater testing. And, yes, shortening the leads should help.

 If this solution becomes an "answer" for most then we'll find a way to accommodate it on the PCBs. D5H of 1N5818 (1A) instead of 1N5820 (3A) would help and that's a perfectly fine thing to do.


----------



## adamus

tada

 boxed up and the hum is gone. tiniest bit of white noise but no annoying distant wasp. I believe we have cracked it

 Thanks guys!


----------



## zkool448

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_tada

 boxed up and the hum is gone. tiniest bit of white noise but no annoying distant wasp. I believe we have cracked it

 Thanks guys!_

 

Congrats adamus. Step-by-step details/instructions please!


----------



## cfcubed

*BoM case:*
remove existing C3H (47uf). Replace D5H (1N5820) with 1N5818 to gain room for larger C3H if necessary. Watch polarity.
replace w/330uf* 50v cap that fits. Low impedance preferred. Use 35v rated cap if space demands it. Watch polarity.


*Non-BoM case:*
if space below PCB insufficient for cap, follow "BoM case" procedure above.
if space below PCB sufficient for cap, supplement existing C3H with 270uf -> 330uf* 50v cap that fits. Low impedance preferred. Use 35v rated cap if space demands it. Watch polarity.

** Edit/update: My personal listening tests indicate 247uf of low impedance capacitance is sufficient to eliminate any audible hum/noise contributed by CTH heater supply (in my setup). Scope showed minute improvement over this for 330uf AFAIR. Scope showed no improvement going to 470uf & above AFAIR.* 
 As my posts note, comparisons were done against battery heater supply w/onboard CTH SM heater supply disabled... That's part of the process that lead to this suggestion.

Above revisions & findings support standard CTH tube heater target loads (up to 4W (tube series heater voltage * series amperage draw)). 
 Anyone experimenting w/heater draws > 4W must do just that - experiment


----------



## sachu

Nice work guys..though I have never had a problem with any of mine the guy I sold my prototype CTh to has a slight hiss/hum with IEMs..wonder if these mods would make that go away too.


----------



## zkool448

awesome - I'll hold off on the fix until I get the case done. cheers


----------



## holland

Regarding the 35V, watch the unloaded voltage (no tube). The reason why 50V was spec'd on the stock configuration is because unloaded 24V rectified is about 31V accounting for the diode drops. Unloaded transformers also run higher (though there will be the buffer load), and some may use different transformers. That's getting uncomfortably close to the 35V rating. For those that don't care (like me for my own personal build), I'll use 35V, but if building for others or you do care, use 50V.

 In all likelihood, once Alex blesses it he'll move for a 50V replacement, seeing as the current value is 50V and going lower may have longevity issues.


----------



## sachu

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Regarding the 35V, watch the unloaded voltage (no tube). The reason why 50V was spec'd on the stock configuration is because unloaded 24V rectified is about 31V accounting for the diode drops. Unloaded transformers also run higher (though there will be the buffer load), and some may use different transformers. That's getting uncomfortably close to the 35V rating. For those that don't care (like me for my own personal build), I'll use 35V, but if building for others or you do care, use 50V.

 In all likelihood, once Alex blesses it he'll move for a 50V replacement, seeing as the current value is 50V and going lower may have longevity issues._

 

its a very good point you make.

 unloaded rectified on my builds have been about 34 volts..so a 50 Volt cap is a must in my case.


----------



## runeight

Hey guys, nice work. I hope this solves the problem for everyone and we can get back to business. 
	

	
	
		
		

		
		
	


	




 Holland is right about the cap voltage. It may be hard to fit a 50V cap into the space available, even with a smaller diode so if you can't then use 35V. As long as the voltage stays below 35V you're probably ok. Temperature has a much larger effect on the life of electrolytics than voltage. But, running a 35V cap at close 35V will shorten its life.

 When wiatrob is ready to make new boards we can address this problem. Hopefully there is enough room to move things around for this cap.


----------



## adamus

Alex + CFcubed, thanks for your help on this one. 

 I now have the feintest of noise, and i can live with it whereas before it was intrusive between tracks and silent sections. 

 Giving it a good listen now, its good and a very different sound to the bijou...... but the bijou is still your best imho. Its so rich and spacious.


----------



## cfcubed

Heh. If only my invisibility cloak worked when the wife comes up w/the honey do list
	

	
	
		
		

		
		
	


	




 Only kidding of course. Nice when empirical proves theoretical tho.


----------



## adamus

my humble apologies! (check the edit)

 any reason why this little beasty wouldnt work with a 6n6p? too little gain. 

 The heater current is big (700ma +) but looking at the circuit it should be able to handle it.... maybe with a heatsink on the switcher.


----------



## wiatrob

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_any reason why this little beasty wouldnt work with a 6n6p? too little gain. 

 The heater current is big (700ma +) but looking at the circuit it should be able to handle it.... maybe with a heatsink on the switcher._

 


 It does - I just called it the 6H6P (my Cyrillic is bad) in my six volt listening report from last night...


----------



## holland

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_my humble apologies! (check the edit)

 any reason why this little beasty wouldnt work with a 6n6p? too little gain. 

 The heater current is big (700ma +) but looking at the circuit it should be able to handle it.... maybe with a heatsink on the switcher._

 

As wiatrob stated, it does. I've used it in mine for a while, till I checked the temps. Since then, I've added some venting to my prototype so I should be able to use it again.

 I know wiatrob is running a 1A version, and I'll be joining that later on. Woo, woo, 900mA heater tubes...because it's there.


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Hmmm, what if you do? I keep thinking about a special HeadphoneAddict Edition. 
	

	
	
		
		

		
		
	


	


_

 

The CTH HA SE - Hmmm... Is that one with an on off switch and an orange LED to light up the tube? (I bought an APS "1/8" male to RCA female adapter", so I don't need RCA jacks anymore). 

 I am trading off my EF1 and will likely start to miss having a little compact tube hybrid around, now that Blutarsky has my TTVJ Millett Portable Hybrid and my son has the Starving Student. My Qinpu A-3 tube hybrid is much bigger and more of a speaker amp, that just happens to drive many headphones via pre-amp out.


----------



## rds

Thanks to everyone who made time to solve this hum problem.

 My search at Digikey shows that a 50V 330uF Nichicon PW is the best option for the BOM case as far as what they have in stock. The dimensions are 10x20mm which should fit by my measurements, and the top of the cap will be level with ICH (allowing for a heater switch above).
 ...of course the 5mm leads will have to be bent slightly to fit the 3.5mm holes.


----------



## wiatrob

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_...of course the 5mm leads will have to be bent slightly to fit the 3.5mm holes._

 

Was wondering when you'd de-lurk! 

 It looks like this is a fairly simple fix (I have already checked the fit in early hum-removal tests.) I'll grab some caps and do a test, then we'll probably update the BoM.

 Maybe we can add the 1A heater parts to the Tweaks section...Holland, did you get any temp measurements on the switch reg?

 I don't have a thermocouple


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Holland, did you get any temp measurements on the switch reg?_

 

Nope, not yet. I have not implemented the tweak. I'm extremely busy at work and have absolutely no free time during the day. I'll try to get to it this weekend, time permitting.


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Thanks to everyone who made time to solve this hum problem.

 My search at Digikey shows that a 50V 330uF Nichicon PW_

 

Good except that is not a low impedance cap.... I'd like to see some sort of low impedance cap there, but it's not as critical that it is low impedance cap as all the others in the heater circuit.


*Add me to the hum-less
	

	
	
		
		

		
		
	


	


* 

 Only low impedance 35v+ caps I could fit under my PCB were two 100uf - 63 volters. So total 247uf for C3H & no hum whatsoever with tubes that had no hum w/battery heater supply (6922 & 6DJ8 that did have some hum w/stock 47uf C3H). 

 IOW I find CTH using onboard switcher with 247uF of C3H capacitance indistinguishable from disabled switcher/battery powered heater. It's an even more wonderful amp than it was before
	

	
	
		
		

		
		
	


	




 We are done with this issue I think. So just consider pulling stock 47uf C3H & replacing w/10mm dia - 20mm height (max size) 330uf 50V low imped cap.


----------



## rds

hmm, well maybe a Pansonic FM 270uF 50V is a better choice from Digikey. 0.023 ohms is pretty reasonable I think 
	

	
	
		
		

		
		
	


	




 Wiatrob - when the crap hits the fan, I go on lurk


----------



## keyid

if anyone going to order the new caps for c3h, let me know. 
 Can help out with shipping cost.


----------



## zkool448

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Wiatrob - when the crap hits the fan, I go on lurk_

 

Typical Canadian....


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_hmm, well maybe a Pansonic FM 270uF 50V is a better choice from Digikey. 0.023 ohms is pretty reasonable I think 
	

	
	
		
		

		
		
	


	


_

 

If that's the highest uF low imped cap w/max 10mm dia X 20mm H that Digikey has available, think it will be fine. On scope I _think_ 220uf + 47uf did not look as good as 330uf + 47uf BUT the 220uf I used was not low imped & based on scoping low impeds did better AFAIR. *So think that 270uf is a good choice if ordering from Digikey & that's whats available.*

 BTW *good to look at the Description as well as attribute/column for size*... As usual @ Mouser I see differences in the 330ufs shown by my query/link (listed as 10x16 - desc says 10x20, listed as 10x20 - desc says 10x31, etc).


----------



## cfcubed

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_if anyone going to order the new caps for c3h, let me know. 
 Can help out with shipping cost._

 

Would like to get in on this myself for C3H replacement in my 1st/protoPCB CTH... A mini GB or something for a cap from my Mouser query OR that 270uf Digikey one would be nice... Maybe start another thread for it?

*Edit: I've updated my C3H revision guide*. Again.


----------



## tacitapproval

I have been out of town this week and have missed all the excellent troubleshooting, not that I would have been able to contribute much. I am very excited that a solution has been found. Nice work folks. 

 I ordered a 35v nichicon pw from digikey, along with a few other things I needed. Sounds like this was premature, so if there is a groupbuy of a more appropriate cap, I would like to get in on it.


----------



## wiatrob

Quote:


  Originally Posted by *tacitapproval* /img/forum/go_quote.gif 
_I ordered a 35v nichicon pw from digikey, along with a few other things I needed. Sounds like this was premature, so if there is a groupbuy of a more appropriate cap, I would like to get in on it._

 

CFCubed, Runeight and I have been discussing cap choices. I will be ordering some today to confirm functionality, and then I would like to provide all current builders with this part free of charge. We'll change the BoM and add instructions for installing it.

 If there are some builders outside the US who wouldn't mind re-shipping caps to their countrymates, that would be great, but not necessary.

 I'll have the caps here and tested by Tuesday of next week.


----------



## dBel84

above and beyond my friend - kudos ..dB


----------



## adamus

wiatrob, dont even think of shipping me a cap! no way am i having you buy caps and ship to the uk again - its enough of a service producing the caps, no need to go abover and beyond, but as dbel says, big kudos for offering.

 this si a super little amp with the 6n6p.... easily my favourite tube so far - it just wacks out some heat. maybe some longevity issues but i dont care for my personal build.


----------



## holland

wiatrob, that's very generous offer. I will opt out, however. I have boxes full of caps, I've got plenty of 470uF-1000uF/35V-50V caps just lying around.


----------



## wiatrob

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_wiatrob, dont even think of shipping me a cap! no way am i having you buy caps and ship to the uk again -SNIP._

 

Excellent, that's just the response I was looking for! 
	

	
	
		
		

		
		
	


	




 Seriously, I am happy to provide these to all - the offer is especially aimed at those who are stepping up from easier DIY builds (SS's or CMOYS) I want to make sure they have the full experience this amp can offer.


----------



## Forte

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Maybe we can add the 1A heater parts to the Tweaks section_

 

What parts need to be upgraded and has anyone tested this yet?


----------



## holland

inductors with more current capacity, whether or not to increase C1H and C2H is still not clear. wiatrob has one, I will be modding mine soon as well.


----------



## adamus

I am going to try increase c1h and c2h just to see if i can iron out that last bit of noise.


----------



## rds

I'm wondering why I haven't seen a CTH in the bom case with mini jack input and 1/4" output. It seems like there's plenty of room on the front for this.


----------



## sachu

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I'm wondering why I haven't seen a CTH in the bom case with mini jack input and 1/4" output. It seems like there's plenty of room on the front for this._

 

heh..you must have missed mine then...

 I have RCA inputs and a 1/4" Neutrik jack in the small BOM case.


----------



## rds

I'm surprised the RCAs aren't hitting ICH. But it looks like you have no fuse or heater switch. I want to have fuse, power switch, heater switch, 1/4" and mini jack. I'd prefer the mini jack or even RCAs on the back but it seems impossible even to jam a mini jack on the back panel.


----------



## sachu

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I'm surprised the RCAs aren't hitting ICH. But it looks like you have no fuse or heater switch. I want to have fuse, power switch, heater switch, 1/4" and mini jack. I'd prefer the mini jack or even RCAs on the back but it seems impossible even to jam a mini jack on the back panel._

 

I will be adding the power switch later. The ICH is slightly bent forwards towards the front of the amp to make space for the RCAs. There is however no space for a fuse in the back with the RCAs..

 I could have moved the RCAs to the front or put a mini in the front for the input and then put a fuse in the back but I didn't.


----------



## MrSlim

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_Typical Canadian.... 
	

	
	
		
		

		
		
	


	


_

 

Nah.. we send in the JTF2


----------



## MrSlim

So is someone doing a miniGB for C3H? If so, I'd like to get in on it too..


----------



## rds

My little contribution to this project. This was drawn for the Spruce Canyon labs kit in particular (for the fuse and switch placement), but the greyed out areas apply to all standard builds in the (small) bom case.
 I'm calling this a prototype because I haven't had a chance to use it yet, but I'm pretty sure everything is right.
 I'll post a link to the pdf shortly.






 PS I know on Cavalli Audio the center of the AC jack is shown as 18mm, but my measurements don't agree.
*
 Download* the pdf here


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Holland, did you get any temp measurements on the switch reg?_

 

Did the upgrades, using a 470uF/35V C3H, 220uF/10V C1H & C2H, and the 2 inductors. The muriata is a bit too tall for my build, had to find space underneath. I think the digikey 1A version of the stock coil may fit better.

 No noise, BTW, with IEMs (Crossroads Mylarone x3), using a 120R resistor right on the jack, not in R18 (didn't feel like changing it on my proto build). Didn't make it straight wire, too lazy. 

 Anyhow, on my build with the rear open to measure the switcher directly (it has a small heatsink on it and under the PCB) it is @ 65C, idling. Tube is fully out of the case using a socket saver. With the rear fully enclosed, and measuring temperatures inside the case, it's 55C.


----------



## cfcubed

Quote:


  Originally Posted by *MrSlim* /img/forum/go_quote.gif 
_So is someone doing a miniGB for C3H? If so, I'd like to get in on it too.._

 

Looks like  Bill _may be_ offering his full kit customers a way to get C3H replacement for free, and some of them may take him up on it. His support of the CTH kits & his customers is extraordinary. At this rate they could wind up expecting greeting cards at holidays & their birthdays from him as well
	

	
	
		
		

		
		
	


	




 My thinking is that the heating circuit designer & those on the proto PCB teams (aka "the guilty"
	

	
	
		
		

		
		
	


	




) could just just pay Bill his cost plus a buck or 2 for his troubles as one way to get the replacement. Once a cap is IDed and confirmed & if he orders enough in some future order.

 But as DIYers, although we don't like admitting it, we are only one step away from _another_ parts order at any point in time, so that's another way to go


----------



## cfcubed

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_boxed up and the hum is gone. tiniest bit of white noise but no annoying distant wasp. I believe we have cracked it_

 

 Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I am going to try increase c1h and c2h just to see if i can iron out that last bit of noise._

 

adamus - Unless you are working to support tubes w/heater draw > 4W, my wordy research suggests heater circuit tweaks beyond raising C3H to 330uf may not be fruitful. So would be curious to hear your findings. 

 Keep in mind that very, very low level hiss/white noise _(sometimes detectable when music is not playing)_ is unavoidable w/the CTH's class A discrete RS+OB AFAIR. R18 output resistors of 68R -> 150R serve to suppress this hiss & provide better vol pot control.

 One thing that would be great is if someone w/sensitive cans could confirm my findings that raising C3H to 330uf, in support of std CTH tubes w/heater draw < 4W, is comparable to/not easily distinguishable from CTH w/heater circuit disabled & battery heater:
pulling D1H & D3H and *carefully* pulling L1H (watch out for unraveling or loss of coil attachment)
running wires connected to tube pins #4 & #5 external to the case.
creating a 6V pack out of 4 "D" cells tapped & soldered in series
connect neg/- of 6V pack to wire connected to pin #5, positive pin #4
Box things up & try any "noisy" 6.3V heated tubes you have (in an EMI quiet area).


----------



## wiatrob

Nice suggestions CF - I'll look for a 330uF coil at the electronics store tody.

 AFA C3H is concerned I have already made the GB. Caps will be here Tuesday. Nicihicon low impedance, 10x20mm I'll do a test install and then they will be available, per my previous post.

 I'm providing these free to those who got kits. Nux has agreed to redistribute Down Under, as he has a set of perf tops on the way. 


 If anyone would like to do so for Canada, that'd be swell.

 I'll handle US postage.

*EDIT*: If anyone else needs some - please ping me. I'd be happy to send them on for cost + shipping...


----------



## adamus

all,

 I got slightly board, and needed an excuse to try my new soldering iron out so i messed around with different caps in c1h and c2h. 

 no change. scoping around, the remaining noise is mainly from the buffers. 

 However, i do still notice slightly noise on the 24v rail when a tube is plugged in. much much reduced from before but its still there. 

 overall i am now very happy with this amp, its a solid little performer and a refreshing change to the bijou. Switching between two very different sound signitures is good fun.


----------



## cfcubed

To my surprise I found a std 470uf 35v 10mm dia X 16mm H cap in my stash. Pulled C3H in my orig CTH in std BoM case & was able to fit the 470uf in its place. Now no hum whatsoever in that CTH either.

 So *I've updated my C3H revision guide*. Again. Message is if you've any 270uf -> 470uf 35V+ cap that fits it should do the trick.


----------



## holland

wiatrob, running the 6N6P-i (900mA heater) that I "borrowed" from my Bijou. I'm not sure if it's the best operating point for it, but the 900mA mod is working well so far. I'm not sure if it matters, but using 470uF/35V C3H, and 470uF/16V C1H & C2H (wanted to try 12V tubes again). I'll have to do a comparison against my other 6N6P some day, but this seems to have a bit more kick. I say seems as I've been hoping between tubes and amps like crazy this weekend.


----------



## wiatrob

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_ I say seems as I've been hoping between tubes and amps like crazy this weekend._

 

I know what you mean - I've collected so many tubes I have to limit myself to one per week to make any sense out of it. I'll be grabbing the 6N6 and 6N23's this week @ work...

 I added a small stick on heat sink for ICH. Realized if it cam unstuck it would fall directly on D1-4H, so I put a small screw through it. Probably overkill.


 Nothing but 'baby' inductors available at the store tis weekend, so no chance to try upping the value of L1/2H.


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Nothing but 'baby' inductors available at the store tis weekend, so no chance to try upping the value of L1/2H._

 

Guys, if you want to investigate heater > 4W support, consider downloading Switchers Made Simple® V4.3. It's a good ol' DOS app. 

*For inductors*, it appears to *report best/optimal values* but be sure to review LM2595-ADJ chart on page 12... 220uH main coil seems best compromise value for std heater targets (6.3v / 12.6v loads <= 4W). But it seems the tool *may report minimum values for caps* & this would make sense because most designers are looking for lowest-cost solutions. We aren't
	

	
	
		
		

		
			





 For what you are after, ripple filter comp values require you need to dig deeper. Optimal ripple filter cap value might be 180uf -> 220uf for what you are trying to do. But remember, it seemed heater circuit noise was NOT from tube heater element side of switcher, but from switcher's impact on common A/C. You will have to get cozy w/your scope I think, but don't forget your ears are the real judge


----------



## wiatrob

I was wondering where that app was located - thanks for the pointer. Your hunches about the ripple caps seem to be on the mark - I noticed no difference on the scope when I went from 100u ->200u


----------



## holland

Thanks cfcubed. I did it the old fashioned way with the datasheet, which suggests a 220uF C2H, which is why I went with 220uF-470uF. I'm also using a 470uF C1H Panasonic FM, min should be about 330uF @ 1A. The larger value inductor (L1H) should be used for lower currents, i.e., 330uH for 150mA loads (12AU7, etc.). 

 Scope indeed, but no time for me till the weekend at the earliest.

 I'll check out your link soon. It sounds like a nifty tool.


----------



## zkool448

I'm slowly catching up and still see a few tweaks happening here and there. I;ve found a spare C3H 470u/35v but I think will let the dust settle and wait until Alex's site is updated with the official word (bom changes/tweaks/suggestions/etc.) 
	

	
	
		
		

		
		
	


	




 thanks all for working so hard on this!


----------



## holland

Just use it.


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Just use it. 
	

	
	
		
		

		
		
	


	


_

 

Agreed. Others are only messing around w/other components to support > std 4W tubes (for some heavy heaters).


----------



## zkool448

I plan to holland 
	

	
	
		
		

		
		
	


	




 I'm just patiently waiting for tweaks others are also trying, observe for green light, then patch 'em all into the board in one sitting


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Agreed. Others are only messing around w/other components to support > std 4W tubes (for some heavy heaters)._

 

And when it's all said and done, I'll probably migrate back to my trusty RCA 5963 BPs


----------



## adamus

I have been using the 6n6p for a while now on stock parts apart from the larger cap.... no issue so far.


----------



## olblueyez

So the noise problem was due to the use of particular tubes?


----------



## adamus

it was due to noise from the heater supply. Using a larger value cap seems to have cured it. Tubes drawing more filament current made the problem worse, hence the 12au7 often seeming very quiet, and the thirsty 6n1p humming on a lot of builds.


----------



## olblueyez

Cool, I get it now.


----------



## smeggy

I like it when collective brain cells get to work on a problem, very cool.

 I should have mine properly cased up soon too so that'll be fun, though not quite 'compact' any more


----------



## zkool448

x2!

 smeggy, just say you're not going for that 'compact' look... that's what I tell people, and I'm sticking with it 
	

	
	
		
		

		
			





 Loking forward to seeing yours.


----------



## smeggy

heh. It's mostly done, just need to make the base and wire it up


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_heh. It's mostly done, just need to make the base and wire it up_

 

ummm..looking forward to this one Smeggy..


----------



## luvdunhill

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_heh. It's mostly done, just need to make the base and wire it up_

 

hopefully it won't have a certain someone's 6-pin jack on the front


----------



## smeggy

Quote:


  Originally Posted by *luvdunhill* /img/forum/go_quote.gif 
_hopefully it won't have a certain someone's 6-pin jack on the front 
	

	
	
		
		

		
		
	


	


_

 

Possession is 9/10ths of the law.. 
	

	
	
		
		

		
		
	


	




 BTW, did you find a 21mm bit? They seem rare over here.


----------



## luvdunhill

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Possession is 9/10ths of the law.. 
	

	
	
		
		

		
		
	


	


_


----------



## wiatrob

10mm 330uF low impedance caps are in (Nichicon UPW1H33MPD.) I am listening now and confirm CFCubed's and Adamus findings. They are a tight squeeze (may need some heatshrink on 'em in your build.)

 Please email or PM me if you got a kit and would like the cap upgrade and are in the CONUS.

 RDS and NUX have volunteered to send caps to Canadian and Australian kit purchasers. Email or PM me and I will coordinate with them.

 I am super swamped at work so it may be a few days before these go out. Thanks for all who pitched in to solve this (really, minor 
	

	
	
		
		

		
		
	


	




) issue...


----------



## adamus

it was minor, but then we are a picky bunch. 

 This is a really goog little amp. Been enjoying it over the last few days. having the bility to just pull a tube, plug one and in and go is GREAT fun. 

 Thanks waitrob for the kit service!


----------



## smeggy

here's a pic of my CTH made from old leftovers, old top plate I had made 4-5 years ago for another unfinished project, bit of old walnut, computer speaker grille and other sundry bits I had in the scrap bin.

 I still need to wire in the new pot, RCAs, power and fix the headphone sockets in place. Make a base frame, add feet and await my black knob from Hong Kong, but you can see the basic idea.






 I call it 'MOAR DARK'


----------



## sachu

holt smokes!!..fantastic smeg... 
	

	
	
		
		

		
		
	


	




 I almost feel like I built that myself


----------



## cfcubed

smeggy - Gorgeous & creative (re-)use of materials... As we've come to expect from you
	

	
	
		
		

		
		
	


	




 Looking forward to completion of zkool448's work of art as well.

 Although galleries (like amb's) may be hard to setup & maintain, they are neat to peruse.


----------



## MrSlim

Smeggy, very nice work, love the "stone in the pond" ripple around the tube.. very cool..


----------



## zkool448

smeggy, love the design -- Very niiiice!! That top plate (steel/metal plate) is nicely machined and like the bling'ed tubes 
	

	
	
		
		

		
		
	


	




 Mine's still under construction, hope to have it done around this time next week.


----------



## holland

Just curious as to what everybody's 6.3V voltage is at? Mine is low (measured it last weekend but didn't have time to do anything other than take a quick measure), going to change R3 to 7.5K which should bring it up to 6.3V.


----------



## sachu

I believe mine is at 6.1x volts


----------



## cfcubed

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_Just curious as to what everybody's 6.3V voltage is at? Mine is low (measured it last weekend but didn't have time to do anything other than take a quick measure), going to change R3 to 7.5K which should bring it up to 6.3V._

 

_Edit: Forget I said this: "Would be interested what voltage your 12.6V setting would then be." R3H is not involved in 12.6v setting._

 6V heater setting is combo of R1H & R3H values. I get like 6.18V (6.2V) & 12.57 (12.6V) with BoM values AFAIR. Played a bit with *available* values for those resistors & decided the BoM values were good enough. SMS app values for them were accurate AFAIR.

 Edit: The 6.2V was with target heater load & BoM values. Perhaps there is an ever-so-slightly better available R3H value tho (to get exactly 6.3v). AFAIR the ideal value for std heater loads was closer to BoM 6.98k then to 7.5k. Maybe like 7.1416k? Not something I'm loosing sleep over


----------



## adamus

I get slightly low, 6.15v. Doesnt bother me to be honest, there is certainly no lack of warmth (something i found with the my bijou that had low heaters)


----------



## holland

Cool, thanks. Going to bring that up in time, to see the impact. Re: adamus & Bijou. Currently running my Bijou @ 6.5V heaters.


----------



## adamus

with 6n1p in the front end i ran mine hot too, definately a richer sound. With a 6dj8 in the front, i stick at 6.3v.


----------



## wiatrob

If I recall correctly, my 6V measurement was rigjt around CFCubed's. I can't hear those subtle differences...


----------



## HeadphoneAddict

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_here's a pic of my CTH made from old leftovers, old top plate I had made 4-5 years ago for another unfinished project, bit of old walnut, computer speaker grille and other sundry bits I had in the scrap bin.

 I still need to wire in the new pot, RCAs, power and fix the headphone sockets in place. Make a base frame, add feet and await my black knob from Hong Kong, but you can see the basic idea.






 I call it 'MOAR DARK'_

 

Wood Etch-a-Sketch?


----------



## smeggy

...with moar dark


----------



## holland

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_My search at Digikey shows that a 50V 330uF Nichicon PW is the best option for the BOM case_

 

 Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Good except that is not a low impedance cap.... I'd like to see some sort of low impedance cap there, but it's not as critical that it is low impedance cap as all the others in the heater circuit._

 

I just clicked these links. 

 I'm not sure I see a difference. Nichicon PW is low impedance (0.090ohm @ 100KHz & 20C ESR) and the link from rds is the same you are pointing to. I think?

 Anyhow, Nichicon PW FTW.


----------



## wiatrob

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_
 Anyhow, Nichicon PW FTW. 
	

	
	
		
		

		
		
	


	


_

 

I'm staring at a sackful here on the bench 
	

	
	
		
		

		
		
	


	




 Let me know if you want a couple...


----------



## holland

Thanks for the offer, but I'm good. 
	

	
	
		
		

		
		
	


	




 I used Panny FM 470uf/35V from my stash.


----------



## wiatrob

As for under-heated tubes - 7DJ8s can be added to the list as well. 
	

	
	
		
		

		
		
	


	




 Silent @ zero volume with the 330uH and very nice sounding...


----------



## rds

I really like this amp


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I really like this amp 
	

	
	
		
		

		
		
	


	


_

 

That's what we like to hear. The whole point of the adventure for me.

 Great looking build.... Belongs in the CTH build gallery


----------



## olblueyez

Smeggy and RDS, nice looking amps!


----------



## Forte

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_As for under-heated tubes - 7DJ8s can be added to the list as well. 
	

	
	
		
		

		
		
	


	




 Silent @ zero volume with the mods and very nice sounding..._

 


 Talking of underheated tubes, got what was supposed to be two 6FQ7/6CG7 tubes from eBay today. One is fine, but the second is a 8FQ7/8CG7(8.4V heater), was going to return it for a refund but after reading your post plugged it in and it sounds great even at only 6.3V!

 Have only had a short listen today but the 6CG7 sounds fantastic, one of my favorite tubes already.


----------



## wiatrob

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Have only had a short listen today but the 6CG7 sounds fantastic, one of my favorite tubes already._

 

Yes, a very nice tube.


 RDS- Nice looking! I am considering including that switch as part of the next round (Holland has suggested a smaller one as well), as stocking issues will force a kit part change most likely...


----------



## holland

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Talking of underheated tubes, got what was supposed to be two 6FQ7/6CG7 tubes from eBay today. One is fine, but the second is a 8FQ7/8CG7(8.4V heater), was going to return it for a refund but after reading your post plugged it in and it sounds great even at only 6.3V!

 Have only had a short listen today but the 6CG7 sounds fantastic, one of my favorite tubes already._

 

They are my tube of choice for many an amp.


----------



## dBel84

There was a reason stax chose them (6FQ7 at least) and I have to agree, they are by far my favourite tube ..dB


----------



## lgn

This might seem like a silly question, but when do I use the 12.6 V setting and 6.3 V setting.


----------



## smeggy

Quote:


  Originally Posted by *lgn* /img/forum/go_quote.gif 
_This might seem like a silly question, but when do I use the 12.6 V setting and 6.3 V setting._

 

Ditto, it's not like the tubes come with instructions. I would have no idea myself.


----------



## cfcubed

Quote:


  Originally Posted by *lgn* /img/forum/go_quote.gif 
_This might seem like a silly question, but when do I use the 12.6 V setting and 6.3 V setting._

 

Mostly from this old post to this thread

 12.6v heater:
 12au7 variants
 ecc82
 6680
 6189
 5963
 7316
 5814
 12bh7
 8416 (12.6V 6922)

 6.3v heater:
 6922
 6dj8
 6n1p (a bit much draw?)

 And some are running 7v/8v tubes @ 6.3v as just posted & there may be a couple more tubes than this list.

 A way to confirm is to search for the tube's datasheet (e.g. 12bh7 pdf) - series heater voltage. There are some tube info repository sites too...


----------



## runeight

In general, and obviously so, tubes that start with 12 should use the 12.6V setting. Tubes that start with 6 use the 6.3V setting.

 But then we get into the European labeling system with the ECC types and you just have to look them up.

 Then there are the pure numbers. These are frequently military or specialized versions of the normal tubes. Some are made more rugged for example, or low noise.

 You'll have to look these up too.

 Try this website:

Frank's Tubes

 It has nearly everything that's ever been produced.


----------



## lgn

I am done the amp now but it seems that the led starts off as green, red never shows up. Also it seems that the amp on full volume doesn't seem to be very loud on my k702. I haven't tested the voltages yet and I will get to that asap, but any suggestions before that?

 Thanks


----------



## runeight

Ign, there isn't much else to do but to start measuring voltages.

 First question is, are the green and red LEDs in the right places? If so, you're saying that the red LED never lights up and that the green comes on immediately?

 If you could please measure OG with respect to SG and then OL and OR with respect to SG this will get us started.

 Thanks.


----------



## zkool448

more pics in build gallery


----------



## HeadphoneAddict

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_










 more pics in build gallery_

 

ABSOLUTELY STUNNING! yes, i was yelling.

 Ummm, would be better if the HP jack was in front, ya think?


----------



## smeggy

Very pretty zk, as always 
	

	
	
		
		

		
		
	


	




 Alex, thanks for the tube info/tips.


----------



## holland

nice work, zk. you have too many tools, and obviously too large a workspace.


----------



## cfcubed

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_more pics in build gallery_

 

Very, very nice!

 How's it sound?


----------



## zkool448

Thanks guys! This little guy is a really really nice amp and I can't wait to get this setup at the office tomorrow. 
	

	
	
		
		

		
		
	


	




 Been following the tube/tweak thread and gathered few ideas on which tubes to try. Good tube reviews except strangely, I can only relate particularly to adamus' tube impressions -- will likely go with his recommendations in terms of tube selections 
	

	
	
		
		

		
		
	


	




 headphoneaddict, the hp jack would've been good in front, sadly that huge honkin knob took up all the real estate. 
	

	
	
		
		

		
		
	


	




 I do like the RK097 pot with the on/off switch built-in, saved me from drilling an extra hole. I thought I'd get some hum when I ran an ac wire to the front (one side of board) but fortunately did not introduce any negative effects whatsoever.
 cheers.


----------



## holland

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_headphoneaddict, the hp jack would've been good in front, sadly that huge honkin knob took up all the real estate. 
	

	
	
		
		

		
			



_

 

I kept thinking of all sorts of crude jokes about rears, but I won't post them. 
	

	
	
		
		

		
		
	


	





  Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_fortunately did not introduce any negative effects whatsoever._

 

Excellent. It may induce some measurements that are less than stellar, but you won't know if you don't hear it unless you go searching for it. I, personally, have no issues with routing AC to the front if one uses care and goes around the sides especially in a large case as yours.

 So....wanna do a run for a few of us? 
	

	
	
		
		

		
		
	


	




 You knew that was coming, right?


----------



## adamus

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_Been following the tube/tweak thread and gathered few ideas on which tubes to try. Good tube reviews except strangely, I can only relate particularly to adamus' tube impressions -- will likely go with his recommendations in terms of tube selections 
	

	
	
		
		

		
		
	


	



_

 

I dont think its that surprising that the 8416 features highly on my list, you only have to look at the operating point to realise the 12au7 / 6dj8 should be the most linear with the CTH. 

 tubes like the 6n6p sound good, but have a look at the datasheet.... we are in a horrible operating region.


----------



## olblueyez

There are so many 12AU7/ECC82 variants why mess with tubes that may not be compatible?


----------



## tacitapproval

Quote:


  Originally Posted by *olblueyez* /img/forum/go_quote.gif 
_There are so many 12AU7/ECC82 variants why mess with tubes that may not be compatible?_

 

Because this is DIY!


----------



## holland

Quote:


  Originally Posted by *adamus* /img/forum/go_quote.gif 
_I dont think its that surprising that the 8416 features highly on my list, you only have to look at the operating point to realise the 12au7 / 6dj8 should be the most linear with the CTH. 

 tubes like the 6n6p sound good, but have a look at the datasheet.... we are in a horrible operating region._

 

True enough. The 12AU7 is the design center. so naturally it would be the best fit.


----------



## zkool448

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_So....wanna do a run for a few of us? 
	

	
	
		
		

		
		
	


	




 You knew that was coming, right? 
	

	
	
		
		

		
		
	


	


_

 

Hmmm, ..or perhaps we can barter for a _<blank>_ if you have a _<blank>_. 
	

	
	
		
		

		
		
	


	




 It might just work out quite nicely in this ‘_case_’ 
	

	
	
		
		

		
		
	


	




 * I need some assistance gents (nothing critical), but my question belongs to the tubes/tweak thread… pls check when you can.


----------



## keyid

Thanks to Wiatrob, I switched C3H and the inductors on L1/L2H with 1A and got a 6n6p tube. 

 - With 12au7 its very black. 
 - With 6n6p tube it is very quiet just a faint almost unnoticeable hum, these tubes sound great! 
 - With 6n1p it is also quiet but has a more audible hum but drastically reduced, maybe tubes I have are just noisy. 

 These 6v tubes are making me rethink my 12au7 collection. The switching regulator (ICh) does get pretty hot with 6v tubes and had to add a bigger heatsink on it but still gets hot.


----------



## wiatrob

I have another batch of digi-key parts on the way including the next model up from the BoM spec'd L2 to see if it's a better fit on the board. I have some added capacitance on C1H/C2H (200uH total) and I believe Holland has even more. 

 We have been kicking around the idea of adding this as an official 'tweak' but haven't com \e to a conclusion about ICH heat dissipation - C1/2H values. I added a small sink to mine and will try to get some temp measurements.

 FWIW - I ran it without a sink with the 6H30 for quite a bit with no ill effects (but not hundreds of hours as a _true _test would!)

 EDIT: keyid, did you swap out C3H as well?


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_C1H/C2H (200uH total) and I believe Holland has even more._

 

Yes, currently running 470uF in C1H, C2H, and C3H. I have not measured them yet, unfortunately.


----------



## keyid

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_EDIT: keyid, did you swap out C3H as well?_

 

yes I have along with L1H & L2H.
 I am kinda worried about heat on the C3H being right next to ICH's heatsink, also L2H gets kinda warm. Im thinking I should flip ICH and sink it to the case like ICP on my board.

 Does C1H & C2H also require higher values?


----------



## wiatrob

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_yes I have along with L1H & L2H.
 I am kinda worried about heat on the C3H being right next to ICH's heatsink, also L2H gets kinda warm. Im thinking I should flip ICH and sink it to the case like ICP on my board._

 

Do you have a way to measure just how hot it's getting? Flipping ICH would be non-trivial...


  Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_Does C1H & C2H also require higher values?_

 

Unknown. Per Hollands reading of the data sheets, they probably should be bigger. Don't know that saw much difference when I scoped the the difference between 100 and 200uH, but I was looking for another problem...


----------



## keyid

I dont have any temperature reading tools, I can keep my finger on the heatsink but its hot. With the 6n6p, Im now getting some fuzzyness as I turn it on, kinda like short blizzard snow effect then the e12 trips and comes back on and it goes away.


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Per Hollands reading of the data sheets, they probably should be bigger._

 

Err, well, I'm experimenting. Also note that the datasheet explicitly says to not go over 330uF on the output cap...and I'm at 470uF so you know how I like to live. 
	

	
	
		
		

		
		
	


	




 I also didn't have any other sizes available at the voltage rating I was looking for. High ripple rejection is the requirement, not necessarily capacitance. Usually going with higher voltage caps give better ripple rejection, or higher capacitance (watching the 330uF limit).

 You can try pushing the input cap, C1H. Up to 1000uF should be fine.


----------



## wiatrob

I would say being able to keep your finger on ICH qualifies it as 'warm' but not dangerously hot. Unless you are a chef. 
	

	
	
		
		

		
		
	


	




 The fuzziness with turn on is interesting. Holland, have you experienced this? I don't recall this, I'll listen again tomorrow.


----------



## holland

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Holland, have you experienced this? I don't recall this, I'll listen again tomorrow._

 

I've not encountered this. It sounds like it's almost not getting enough juice on start. The xformer is 1.6A?


----------



## keyid

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I would say being able to keep your finger on ICH qualifies it as 'warm' but not dangerously hot. Unless you are a chef. 
	

	
	
		
		

		
			



_

 

its pretty hot, but I my reference for heat by counting secs with a finger have been trained by normally testing soldering irons for heat requirements and skin buildup from awesome guitar solos


----------



## keyid

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_I've not encountered this. It sounds like it's almost not getting enough juice on start. The xformer is 1.6A?_

 

its 1.25A too low?


----------



## sachu

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_its 1.25A too low?_

 

I have the fuzzy thingy on a couple of my CTH builds..but they go away a few seconds after power on.


----------



## holland

That's good to know, sachu.


----------



## Ynis Avalach

So I'd be on the safer side with a 50VA transformer?
 Greetz Ava


----------



## cfcubed

Don't want anyone popping in to thread now to think they need to change anything other than C3H to 330uf _unless they want to support tube heater loads higher than CTH was designed for_.

 IOW, *my C3H revision guide stands for CTH target tube loads. And @ those loads, no other changes are necessary *(ICH heatsink is NOT required, but does no harm). 

*Keep in mind the CTH "design center" is 12au7 variants *and the design heater capacity supports 90%(?) of the tubes that could possibly be plugged into the CTH... Heater tweaks above the basic design may let it support tubes further away from its design center & that could be fun.

 So if > 600ma (4W) series tube heater loads can be supported through some tweaks (the focus of these latest posts) maybe the tweak can make it to the CTH tweaks page when ready. Such a tweak may require switcher heatsink in tight quarters, etc.

 Have fun gentlemen


----------



## wiatrob

YEs, CF - we should probably move this discussion to the tubes and tweaks thread...


----------



## wiatrob

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_its 1.25A too low?_

 

Should be fine. See Sachus comments.

  Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_So I'd be on the safer side with a 50VA transformer?
 Greetz Ava_

 


 For normal use a transformer rated at .83A is fine. _MOAR _does not hurt, however...


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_YES, CF - we should probably move this discussion to the tubes and tweaks thread..._

 

Thanks Bill... We want thread readers to come away with the facts that:
*Only BoM change since production release is C3H -> 330uf. * And you've graciously offered to get the new C3Hs to your kit customers for little or no cost.
*CTH tube compatibility, as designed, is large. * Fleabay usually has > 500 listings for tubes compatible w/CTH in basic form.
*CTH is an intermediate level project *in its basic design form. And, based on other's comments & reviews, competes well against other DIY designs/builds (certainly those costing <= $200).
The *only heatsink the basic CTH design requires is an internal one for the LV 24v reg*. And casework is cake even w/o your extended kit offerings (see my avatar)

_BTW Bill, you mean uH in your inductor values & uF in your cap values in some posts... Don't blame me, my wife is a technical writer/editor & she is always correcting me
	

	
	
		
		

		
		
	


	


_


----------



## wiatrob

*I agree with everything CFCubed says!* I continue to be impressed with the performance of this design. 

 More posts will end up in:

http://www.head-fi.org/forums/f6/cav...thread-417322/

 Henry's and Farads Oh My! Chalk it up to dyslexia!


----------



## wiatrob

My loaner CTH will be ay CanJam with Naaman - he and Blutarsky have graciously agreed to coordinate getting it to the show so this little amp can get the exposure it deserves. 

 The fact that it's easily wedged in with shoes doesn't hurt either!

 Naaman will have only one source and if anybody might have a spare to loan, or babysit the CTH for a bit, it would be greatly appreciated.


----------



## rds

There will also be a CTH at the Whiplash Audio table and one at the CryoParts table


----------



## sachu

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_There will also be a CTH at the Whiplash Audio table and one at the CryoParts table 
	

	
	
		
		

		
		
	


	


_

 

nice!!!


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_My loaner CTH will be ay CanJam with Naaman - he and Blutarsky have graciously agreed to coordinate getting it to the show so this little amp can get the exposure it deserves. 

 The fact that it's easily wedged in with shoes doesn't hurt either!

 Naaman will have only one source and if anybody might have a spare to loan, or babysit the CTH for a bit, it would be greatly appreciated._

 

I hope it is okay if I ask Blutarsky to leave my Mullard tube with me, so I don't have to worry about getting it back later? Unfortunately I wont have an extra source.


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_There will also be a CTH at the Whiplash Audio table and one at the CryoParts table 
	

	
	
		
		

		
		
	


	


_

 

Now that is interesting. A nice surprise for me not knowing the players
	

	
	
		
		

		
		
	


	




 Wondering if the builds are "standard" builds & whether they have the C3H revision. But w/the background "noise" at meets the corrected C3H is probably not so important... 

_Edit: Also curious about c4 couplers they might have. Think most that have WIMAs or Sonicap Gen IIs notice a subtle improvement._


----------



## wiatrob

I think Ryan has done the fix. My build should only have 12V tubes available (but not HA's Mullard - That's fine Larry!) - I haven't seen it in months but I'll mod it as soon as it get's back from the 'Jam! (Blutarsky had noticed some noise with his IEMs, the fix should cure it...)


----------



## sachu

I will be taking my CTH along with me as well to Canjam..will probably request to set it up on someone's table.

 Chris, I totally see now what you mean by an amp for 150$ that you can thrown in the bag and go


----------



## rds

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Now that is interesting. A nice surprise for me not knowing the players
	

	
	
		
		

		
		
	


	




 Wondering if the builds are "standard" builds & whether they have the C3H revision. But w/the background "noise" at meets the corrected C3H is probably not so important... 

Edit: Also curious about c4 couplers they might have. Think most that have WIMAs or Sonicap Gen IIs notice a subtle improvement._

 

The have the corrected c3h and Sonicap Gen IIs


----------



## Ynis Avalach

Good evening (for some of us, I guess).
 I'm kinda new around in the CTH thread, and was wondering if someone could point me in the right direction concerning the following question:

 1. Is it better to have 2 fuses (on the primary side and the secondary side, since I've got a toroid now (50VA)) or just a single?

 Greetz and thx for every help!
 Ava


----------



## sachu

Just use one fuse on the secondary side...


----------



## Ynis Avalach

Thank you!


----------



## smeggy

The C3H cap, is the one posted (I ordered it) just one that will fit or is there a different one that may be better if there's no space restriction?


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_The C3H cap, is the one posted (I ordered it) just one that will fit or is there a different one that may be better if there's no space restriction?_

 

Based on my research, most of which posted here, I found no improvement audible or on scope going above 330uF low impedance cap. But if you don't have a 330uf low imped around anything from 270uf -> 470uf should do.


----------



## smeggy

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Based on my research, most of which posted here, I found no improvement audible or on scope going above 330uF low impedance cap. But if you don't have a 330uf low imped around anything from 270uf -> 470uf should do._

 

Great news, thanks. 
 I got it in the mail today so now I'm set. Just gotta fit it and slap it in the case and wire it up with all the right connectors, which should arrive tomorrow


----------



## wiatrob

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_The have the corrected c3h and Sonicap Gen IIs 
	

	
	
		
		

		
		
	


	


_

 

The amp with Namaan has socketed coupling caps - wimas are in now, so if anyone is inclined to Cap Roll 
	

	
	
		
		

		
		
	


	




 It's had VitQ's and Obligato Golds...


----------



## wiatrob

Double Post


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_The amp with Namaan has socketed coupling caps - wimas are in now, so if anyone is inclined to Cap Roll 
	

	
	
		
		

		
		
	


	




 It's had VitQ's and Obligato Golds..._

 

He was too busy with pizza and beer at the pool and wont get the CTH till Sunday morning...


----------



## SACD-Man

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_He was too busy with pizza and beer at the pool and wont get the CTH till Sunday morning..._

 

Why did not you invite me??

 The CTH is ready and willing by those who want to check out this great amp....


----------



## HeadphoneAddict

Quote:


  Originally Posted by *SACD-Man* /img/forum/go_quote.gif 
_Why did not you invite me??

 The CTH is ready and willing by those who want to check out this great amp...._

 

Didn't know how to reach you, sorry!


----------



## wiatrob

There will be plenty of CTH to go around - hope everyone gets a chance to listen to this amp today!


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_He was too busy with pizza and beer at the pool and wont get the CTH till Sunday morning..._

 

I know how these things go (where's the HICCUP Smiley?)


----------



## smeggy

Just stuck the new cap in mine, now just waiting on more tubes to play with.


----------



## wiatrob

So Sachu, let us know how it sounds being driven by a dac that costs 10X the amp price!


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_So Sachu, let us know how it sounds being driven by a dac that costs 10X the amp price! 
	

	
	
		
		

		
		
	


	


_

 






 well I sold my last CTH to fund my Canjam trip ..but not to worry..Looks like I will be building 3 more at least. 
	

	
	
		
		

		
		
	


	




 by the way, I plonked the CTH with a Siemens E82CC on the Audeze table on Sunday...Folks loved the combo.


----------



## smeggy

so is the Audeze the cats whiskers or what?

 Congrats on the raffle too, lucky git!


----------



## wiatrob

I saw the CTH's in the pictures, but there was so much gee-gaw gear there, I don't know if our little amp got that much listening time...


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_so is the Audeze the cats whiskers or what?

 Congrats on the raffle too, lucky git! 
	

	
	
		
		

		
		
	


	


_

 

heh..told you to come you old fart 
	

	
	
		
		

		
		
	


	




 We missed you man...and so did we miss a lot of other folks. Next time perhaps.


----------



## keyid

any chance you tried the hf2 with the cth? any comparison to rs1?


----------



## sachu

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_any chance you tried the hf2 with the cth? any comparison to rs1?_

 

Very good match. Been a long time since I liked a Grado. The only other grado I liked wwas a pair of RS-1s.


----------



## keyid

those kinda answers doesnt help!
 guess I just have to listen to them.


----------



## sachu

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_those kinda answers doesnt help!
 guess I just have to listen to them._

 

hehe..I am sorry dude..It is very hard to give detailed impressions when I was too darn tired, mind ****ed by all the auditions and running around. All I can say is I would have dropped the 500$ for them if not for the 2 orthos. I plan on buying them both, which sounded quite brilliant with the CTH as well. For most of the second day my CTH was hooked up to the Audeze and was well received.


----------



## keyid

my experience with orthos hasnt been too positive. I have yh-1 that I been trying to mod but the sound seems to go too light sounding to hollow sounding. Havent been able to find a balance yet.


----------



## wiatrob

You will need to spend months with the Ortho Crew & Thread to perfect the Mods 
	

	
	
		
		

		
		
	


	




 You got RS-1s, correct? I _love_ 'em with the CTH (Um, and I didn't like Grados befor ethe RS-1).

 So until you get a chance to hear the HF-2's - enjoy!


----------



## keyid

I was about to get an used rs1 then this dam hf2 appeared. Oh I did skim through that monster of a thread looking at pictures of mods and used that one site which allows searches. I forgot I even had the yh1 and just opened it up for some more tweaking.


----------



## nux

Would anyone in/near Australia be interested in a completed CTH amplifier? I made five, and one person pulled out of paying for one.. So I have a spare fully made and tested, with the C3H modification and perforated top (thanks wiatrob!) and the choice between a few different tubes I have.

 All the rest are working and sounding great!


----------



## smeggy

Australia is pretty close to Seattle isn't it?

 hehe


----------



## runeight

Why yes it is. It's right off the coast of Baja CA. It's a wonder that the marsupials haven't found their way to San Diego yet.


----------



## smeggy

Alex, popped in the 6n6p after the cap upgrade and am loving it. Very nice indeed with plenty of oomph!


----------



## wiatrob

Spot the CTH:

CanJam 2009

 At the verrrrry bottom... RDS' build


----------



## rds

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_At the verrrrry bottom..._

 

Hey, you gotta start somewhere


----------



## wiatrob

rds, any feedback on the CTH from the show?


----------



## sachu

an excerpt from one of the attendees at Canjam.

 "_The Audeze planars were surprising. They sounded pretty good from the short listening session I had. The clarity was almost as good as the Omega II possibly. Its soundstage was very wide, but its imaging wasn't in the same class as the O2s. Of course, the Blue Hawaii and O2 combo costs like $8000 while the CTH(at least I think it was a CTH) and Audeze planar combo costs less than a 1/10 of the price; so, relatively speaking the little amp and headphones held up pretty well. I'd love to take a crack at them again in my room with my set up to see how they compare to my Lambdas since they're one of the few set ups things I listened to that I can reasonable afford at this point - as much as I loved the O2/BHSE as a poor college student I'm not getting that rig any time in the near future unless I win about 10k in Vegas or something._"

 here is a pic of the ortho table and my CTH...this was on the first day before I decided to plonk it on the Audeze table. They were using some obscure amp to drive the headphones.


----------



## rds

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_rds, any feedback on the CTH from the show?_

 

Hopefully Craig (of Whiplash Audio) can fill us in on that. I know he was very impressed with it.


----------



## sachu

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Hopefully Craig (of Whiplash Audio) can fill us in on that. I know he was very impressed with it._

 

Craig told me that his CTH (built by rds) didn't get that much attention as there were a plethora of amps to choose from on his table. Those who did listen to it liked it is what he said.

 However across the room is where the CTH saw a lot more action.. With Locus Design i think (?) Since they only had one or two to choose from.


----------



## SACD-Man

Yep at first the CTH did not get as much action based on so many amps to choose from. I often pointed to Locus Design which was sharing a room. Plus we had so many people in our area that it was often difficult to get to everyone. 

 I did end up moving the amp for a bit. When I did that, more listeners were able to enjoy this amp. Then our ceiling came crashing down because of water. After that, the CTH was moved to where it was originally. 

 I must say I'm very impressed with it. Some actually said it was as good as the Mini Millet Max!! Also being very compact and such, its a great looking and sounding amp!!!

 Great job Ryan and Alex...


----------



## Ynis Avalach

Hi all together!

 I finally finished my board, but am stuck with a little problem.
 The E12 won't switch to green (no sound).
 Pin 1 and 6 of the tube socket are around 104V and 80V without/with tube installed.
 Pin 4 has got 12V.
 I swapped the TL081s around with no change (all three seem to have the same voltages on their legs).
 With a diode test I got the bicolor LED to show me a little green light, red light is working.
 The DC offset is under 10mV for both channels.
 Checked all solder connections.
 But still no sound.

 Could someone please help. My Grado wants tube...
	

	
	
		
		

		
		
	


	




 Thank you for any help

 Greetz Ava


----------



## cfcubed

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_The E12 won't switch to green (no sound).
 <snip of good V measurements>
 With a diode test I got the bicolor LED to show me a little green light, red light is working.
 The DC offset is under 10mV for both channels.
 Checked all solder connections.
 But still no sound._

 

This _seems_ like a case where things may be fine but some issue in your e12 section is preventing it from kicking on the relay (& LED).

 Are your DC offset measurements at the "input" pins of the relay?

 You can see here that the "middle" pins of the set of 3 pairs of the relay are the source/input pins. 
 When I had to diag some things I just ran wire from those middle pins (R, L, OG) for measurements & testing.

 If your true offset measurements at input to relay are ok (< 75 mv per channel or so), then I'd review these parts on your build.


----------



## cfcubed

Quote:


  Originally Posted by *SACD-Man* /img/forum/go_quote.gif 
_I must say I'm very impressed with it. Some actually said it was as good as the Mini Millet Max!!_

 

And heres another opinion on the design, but all amps have their character & all listeners their preferences. 

 Heck I was going to put an old SOHA up for sale & while listening to make sure it was fine decided to keep it


----------



## Ynis Avalach

Bingo, the right channel's got 23V and the left exactly 12V dc offset.
 Ahhhhhh...Any thoughts?
	

	
	
		
		

		
		
	


	



 Ava


----------



## cfcubed

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_Bingo, the right channel's got 23V and the left exactly 12V dc offset._

 

That's a lot of volts. Others are better at helping diagnose portions of CTH other than heater circuit... 

 Know you've posted measurements but maybe crawl through the setup procedure & measurements. Perhaps carefully crawl through the PCB parts images and such...


----------



## TimJo

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_Bingo, the right channel's got 23V and the left exactly 12V dc offset.
 Ahhhhhh...Any thoughts?
	

	
	
		
		

		
			




 Ava_

 

Those are the voltage measurements at the relay?


----------



## Ynis Avalach

Well yeah.
Pins 1 and 12 are 24V
 Pins 3 and 4 are 12V
 Pins 10 and 9 are around 23V (all to SG)

 Strangely all setup points from the CTHs site checked out just fine.


----------



## sachu

So you are saying the OL -> SG is reading 12V 
 OR -> SG is reading 24 V?


----------



## Ynis Avalach

Before the E12 relay that is. Sadly


----------



## Ynis Avalach

Think I found something:
 Isn't R9L-D2L suppost to be at the same voltage as R9R-D2R? (Schematic)
 For the right side I'm reading aprox 23V and for the left aprox 12V. 
 Folllowing it down the line.


----------



## rds

I wonder if you have d2r in backwards?


----------



## Ynis Avalach

No D2R is installed right. Just found this:

 I tested Q8R and Q8L. All voltages related to SG:

 Q8L says, Collector:24,12V, Base: 12,71V, Emitter: 12,12V
 now Q8R gives me Collector:24,12V, Base: 23,78V, Emitter: 23,19V

 So somethings wrong with one of them , I hope (I would guess Q8R).
 I don't have any BC337 so have to wait until tomorrow till I can go hunting down some.

 Do these messurement make sense?


----------



## arteom

OK, I am finished 
	

	
	
		
		

		
		
	


	




 Much thanks to wiatrob for the kit and the support afterward, and the guys who helped me troubleshoot it in the thread that I had started. Oh and Alex for designing this thing, for such a small amp it puts out big sound.


----------



## sachu

^^ Nice job...its a beautiful amp.
 enjoy..


----------



## smeggy

x2, awesome amp and nice build. It's hard to believe how good this little thing is.


----------



## arteom

Thanks guys, was allot of fun building it. Now that I've started in this hobby I don't know if I can stop


----------



## lgn

If anyone could help, I am wondering what the initial voltages across the LED is because mine starts as green and stays as green. My friend's goes from red to green, like it's supposed to, I am wondering if I wired the e12 incorrectly.

 However, the good news is that all my voltages are correct: OG-11.82, OL-11.81, OR-11.79, TB+-96.7, pin1-79.5, pin6-80.1

 As far as I'm concerned, I don't think mis-wiring the e12 will have an effect on the SQ, correct me if i'm wrong.

 Thanks!


----------



## lgn

I found the problem, I switched R8E and R9E. Will fix that tomorrow.


----------



## wiatrob

IGN - best of luck with the swap, hopefully you'll be up soon! Interested to hear your impression sof this amp with the 702s, it's a combination I haven't auditioned yet..


----------



## lgn

sigh*... these problems keep coming, i just swapped them, and my light goes from red to orange (ie both red and green diode lights up)

 any suggestions?

 I am loving the sound so far though, it's one thing that the music is better, but to top it off, i can feel everything much better too, the headphones diaphragms really move. Without the CTH, listening to the k702 is like eating without smell, with the CTH, the extra feeling of the headphones completely adds another sense of touch and it really helps, kinda like the speaker effect.

 But really, I need to figure out why my led is orange now


----------



## wiatrob

lgn - If I understand you correctly, your e12 (and amp) is functioning normally but your e12 LED isn't working?

 This could be bad transistors (Q4,5E) in the led indicator section of the12 (I had a similar problem in my proto build...)


----------



## lgn

That definitely could be happening. I have ran my amp for more than a week on the wrong configuration (R8E and R9E) swapped and that might have blown the transistor. Or I might have just broke one of the pins when I was fixing it a couple hours ago. Either way, the amp is working fine so I am going to live with this lively orange color for now. Thanks for all your help, Bill.


----------



## Ynis Avalach

I exchanged Q8R and Q8L, but still no change.
 How can I test if D2R is not working correct? Diode test isn't working here, is it?
 Greetz Ava

 Please help! pleeeeeeaaseee...


----------



## cfcubed

Ynis - AFAIR Holland & runeight have been very good at pinning down issues in CTH to particular part(s), but I think they may be unavailable ATM.

 Having had issues way back in my proto PCB build, and having incrementally replaced targeted components to no avail, as the parts are available & inexpensive in the US I choose the shotgun approach. I needed the amp going for a meet & couldn't fiddle around.

 It seems to me one buffer is locking up & dumping voltage directly to output.

 Assuming you've *assured all the correct components were installed in the correct places w/the correct orientation & there are no shorts*, just to be clear, what exactly are your measurements for all of the following: 

 # Measure between OG and SG. This should be very close to 12V. If it's not there might be a problem with the TLE2426 or with one of the devices in the rail splitter. 

 # If the OG measurement is good, measure OL and OR (with respect to SG) . They should also be very close to the voltage at OG. If they are the buffers and splitter are working.

 # If OL and OR are not close to OG (>50mV), then either the buffer opamp is not working or one or more of the buffer BJTs are dead (or the wrong hfe class - not possible if you've Bill's kit). IOW, what are your OL <-> OG & OR <-> OG voltage measurements?


----------



## wiatrob

Ynis - If Memory Serves, there was a discussion about CRD function around a problem Adamus had ~post#1028. I just did a quick search but don't remember the exact symptoms or if they were similar to yours, but you might review the posts immediately before and after...


----------



## Ynis Avalach

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Ynis - AFAIR Holland & runeight have been very good at pinning down issues in CTH to particular part(s), but I think they may be unavailable ATM.

 Having had issues way back in my proto PCB build, and having incrementally replaced targeted components to no avail, as the parts are available & inexpensive in the US I choose the shotgun approach. I needed the amp going for a meet & couldn't fiddle around.

 It seems to me one buffer is locking up & dumping voltage directly to output.

 Assuming you've *assured all the correct components were installed in the correct places w/the correct orientation & there are no shorts*, just to be clear, what exactly are your measurements for all of the following: 

 # Measure between OG and SG. This should be very close to 12V. If it's not there might be a problem with the TLE2426 or with one of the devices in the rail splitter. 

 # If the OG measurement is good, measure OL and OR (with respect to SG) . They should also be very close to the voltage at OG. If they are the buffers and splitter are working.

 # If OL and OR are not close to OG (>50mV), then either the buffer opamp is not working or one or more of the buffer BJTs are dead (or the wrong hfe class - not possible if you've Bill's kit). IOW, what are your OL <-> OG & OR <-> OG voltage measurements?_

 

Well I meassured, and OG-SG meassures 12.02V.
 OL-SG meassures 4.6mV (12.01V before the E12)
 OR-SG meassures 1.9mV (23.14V before the E12)
 OL-OG meassures 0mV (but oszialates between 29.1mV and -28.8mV before the E12)
 and OR-OG meassures 0mV (11.14V before the E12)

 Geertz Ava

 btw thank you very much for taking a n interest in my problem Cfcubed!!


----------



## adamus

My issue was high voltage at pin 1, i.e the servo circuit not working, nothing like this i am afraid. In the end the CRD was ok but there was a bridge trace on the opamp pin to ground.


----------



## cfcubed

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_OR-OG meassures 0mV (*11.14V before the E12*)_

 

The 0mv is because the relay/e12 is not engaging due to the actual OR-OG offset of 11.14V. BTW, the whole reason this amp has built-in e12 is exactly for this protection.

 So I _think_ we can say with some certainty its a problem in your Right Output Buffer. As your Q8R vs Q8L indicate. Exactly what is wrong will need to be thought about. Let me think
	

	
	
		
		

		
		
	


	




 Edit: Sorry to ask this (again) & not sure how much below you've already done, but could you *very* carefully review the Right OB components & check above & under PCB for any shorts? 
 And possibly (carefully) re-flow the solder on all the Right OB connections then re-check for shorts. Remove TL082 IC from buffer when you are re-flowing the socket's contacts.

 If this does not solve it, consider swapping Right & Left TL082 ICs & see if OL / OG pre-relay goes to 11.XX volts. To see if its the opamp. If all this does not change/fix OR - OG I'd personally replace all "sand" in Right OB (TO92s + diodes), but that's not the smartest approach


----------



## Ynis Avalach

Yippie....It works!!!!
 Ok my fault!
 I mounted Blackgates 10µF 50V for C5L and C5R and it seemed that C5R wasn't really ok. Have to check it now it's off board.
 E12 relay engaged, hope to hear music soon.
 Thank you very much Cfcubed!
 Now that I have a working BoM I will slowly replace the things I wanted to replace.
 And of course enjoy the music!
 Greetz Ava


----------



## Ynis Avalach

Oh my God beautiful! WOW!!!
 Groovy, aggressive, pure energy, I can't take my crappy hd595 off (Ipod headphone out, not cased yet).
 Thank You Alex! Thank you design team you did a wonderful job in creating this beautiful sounding amp!


----------



## cfcubed

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_Oh my God beautiful! WOW!!!
 Groovy, aggressive, pure energy, I can't take my crappy hd595 off (Ipod headphone out, not cased yet).
 Thank You Alex! Thank you design team you did a wonderful job in creating this beautiful sounding amp!_

 

Hey great to hear all is well... Although this sophisticated design can be a bit tricky to debug think all CTHs are alive & well now
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_As for* under-heated tubes - 7DJ8s *can be added to the list as well. 
	

	
	
		
		

		
		
	


	



 Silent @ zero volume with the 330uH and very nice sounding..._

 

 Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Talking of underheated tubes, got what was supposed to be two 6FQ7/6CG7 tubes from eBay today. One is fine, *but the second is a 8FQ7/8CG7(8.4V heater)*, was going to return it for a refund but after reading your post plugged it in and it sounds great even at only 6.3V! Have only had a short listen today but the 6CG7 sounds fantastic, one of my favorite tubes already._

 

Pretty obvious but been meaning to say that, because of the CTH's innovative heater supply, it would be trivial to support pretty much any heater voltages... Just use National's Simple tools to calculate desired (parallel) values for R1H/R3H and use a SP3T or SP4T heater switch among the various R3H values (6.3v, 7v, 8.4v, 12.6v)...


----------



## TimJo

Glad to read that you figured it out Ynis and that your loving the sound. Just wait until you start rolling tubes...

  Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Pretty obvious but been meaning to say that, because of the CTH's innovative heater supply, it would be trivial to support pretty much any heater voltages... Just use National's Simple tools to calculate desired (parallel) values for R1H/R3H and use a SP3T or SP4T heater switch among the various R3H values (6.3v, 7v, 8.4v, 12.6v)..._

 






 Sounds like a great feature for CTH II.


----------



## Ynis Avalach

Quote:


  Originally Posted by *TimJo* /img/forum/go_quote.gif 
_Glad to read that you figured it out Ynis and that your loving the sound. Just wait until you start rolling tubes..._

 

 I've already got 12BH7, EH ECC82 Gold, JAN 5814A, JAN 6922, Sovtek 6N1P and a Tungsram ECC82 waiting^^.
 Thank you


----------



## smeggy

Excellent news Ynis, glad your working!

 It has almost the perfect signature for me with the right tubes and it's a damn fine amp.


----------



## rds

I'm having an issue with a Amperex 6DJ8 tube in my CTH.

 It sounds great for about 20 minutes and then one of the channels goes bad. It gets quiet and distorted. 
 The tube also seems to get really hot (I know you're thinking I'm accidentally giving it 12.6 V - I even checked and it is definitely 6.3V)

 Has anyone else experienced this? Is the tube dying?


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I'm having an issue with a Amperex 6DJ8 tube in my CTH.
 Has anyone else experienced this? Is the tube dying?_

 

My guess is that the tube is dying... Esp if this does not happen w/your other tubes.

 Both my "bad" tubes do exactly what you describe (in one channel). For both of them I've others of the exact same type that work perfectly.


----------



## TimJo

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_My guess is that the tube is dying... Esp if this does not happen w/your other tubes.

 Both my "bad" tubes do exactly what you describe (in one channel). For both of them I've others of the exact same type that work perfectly._

 

That's been my experience as well. Don't know if yours was an NOS tube, but I had one that went about fifteen minutes, and then one channel slowly faded away. I think after sitting around for decades, if they are going to fail, it seems to happen in the first hour of use. Maybe the dealer you got it from will swap it out for you...


----------



## olblueyez

When you get a bad tube you probably dont want to leave it in the amp trying to figure out whats wrong. Trash it and move on.


----------



## rds

This happens on the same channel of the 3 tubes I've tested so far (and regardless of headphones), so I'm thinking something in the left o/p stage is slightly fried. I did pull out the headphones without turning off them amp :/

 I wonder if the servo is keeping a bad transistor in check until it has warmed up enough that the amount of current its dumping is too large for the op-amp? Does that sound reasonable?


----------



## zkool448

Forunately fo me I've not yet ran into a bad tube (yet!).

 oldblue, I really love the hungarian tungsram and it is as described -- thanks.


----------



## olblueyez

Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_Forunately fo me I've not yet ran into a bad tube (yet!).

 oldblue, I really love the hungarian tungsram and it is as described -- thanks._

 

Great, I am glad you like it.


----------



## rds

maybe q8 is toasted, but it's the warm up thing that throws me off. It takes between 2 and 10 minutes before the channel goes weird. Now there is a constant hiss from that channel and very low volume music very it goes bad.


----------



## rds

after some playing around it appears that the left channel sonicap is bad. Has anyone experienced this?
 If I push on the cap I can start the hissing (which then continues) and if I push it around a bit more I can stop the hissing. It seems like there's a bad connection between the lead and plate.

 Surprising for a $4 capacitor


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_after some playing around it appears that the left channel sonicap is bad. Has anyone experienced this?
 If I push on the cap I can start the hissing (which then continues) and if I push it around a bit more I can stop the hissing. It seems like there's a bad connection between the lead and plate.
 Surprising for a $4 capacitor 
	

	
	
		
		

		
		
	


	


_

 

When this has happened to me its been the contact between the caps leads & the PCB... In fact *exactly* what you described happened to me a couple times in the build I'm using to roll C4 caps.

 Since I'm mounting the C4 under the PCB I could choose to go to a more secure connection spot (e.g. the tube socket pins themselves).

 So before you give up on the cap(s) think about firming up their connections. Even if you have to run a jumper or something below board.


----------



## rds

Thanks for the advice. 

 So you find that solder points for the coupling caps don't make a very secure connection? 

 I'm using tombstoned sonicaps, maybe I should try to reflow the solder joints and if that doesn't work then jumper from the leads under the board to the tube socket?


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_So you find that solder points for the coupling caps don't make a very secure connection? _

 

Not generally. For my case, I consider pulling & changing C4s a bit abusive
	

	
	
		
		

		
		
	


	



 It's probably not unusual that they do not stand for a lot of soldering & desoldering.

  Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I'm using tombstoned sonicaps, maybe I should try to reflow the solder joints and if that doesn't work then jumper from the leads under the board to the tube socket?_

 

Perhaps just the re-flow will remedy the problem. Only need jumpers if the traces / pads are gone or damaged.


----------



## wiatrob

About four rounds of careful desoldering is what the cap pads are good for (he says knowingly)


----------



## rds

Yeah, with the cap removed the pads look and measure completely fine.

 So that makes me worry about the Sonicap since I don't have a spare.


----------



## keyid

if the caps are at fault call Jeff at sonicap they will take glady take the cap back to find out why it isnt working right and probably get you another. I had issues with my sonicap during prototyping or any caps with long leads. I have my Mcap silver/oil leads shielded with small copper tubing.


----------



## rds

*redacted


----------



## keyid

thats what Jeff was saying when I told him that I may have a bad cap, he was pretty surprised. Apparently they have good QC (quality control) and wanted to examine it. If you get store credit I would recommend the mundorfs s/o they sound fantastic on mine.


----------



## rds

I just put in wima mkps and my first impression is that they sound very nice. Perhaps a bit more extended than the sonicaps.

 Do the Mundorfs fit in the small bom case?


----------



## wiatrob

I'd give 'em the benefit of the doubt - I just pulled on twenty, firmly, and they were all fine...


----------



## keyid

The Mundorfs wont fit well, its just about the size of a 12au7 tube.


----------



## wiatrob

I really like the Wimas - especially for the price . Still have them in my proto build...


----------



## sachu

I tried some Janzten audio crossover caps in mine and really liked it...cheap too..


----------



## rds

Miles, Round about Midnight -> Opus DAC -> CTH with Amperex 6dj8 -> RS-1

 is sounding really amazing 
	

	
	
		
		

		
			





 This is definitely one my favorite amps of everything I've owned, built, and heard.


----------



## wiatrob

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_This is definitely one my favorite amps of everything I've owned, built, and heard._

 

It is a pint-sized powerhouse, especially with the RS-1's (and 2's - maybe all Grados!) 

 I have been listening with HD600s at work for the last few weeks... and I feel it accentuates the Senn's _dark _side - but this is not at all a bad thing for some types of music.

 It may well be I now think the Rs-1's are my favorite dynamic...


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_It is a pint-sized powerhouse, especially with the RS-1's (and 2's - maybe all Grados!) 

 I have been listening with HD600s at work for the last few weeks... and I feel it accentuates the Senn's dark side - but this is not at all a bad thing for some types of music.

 It may well be I now think the Rs-1's are my favorite dynamic..._

 

Wait till you hear my HF-2. If you can't afford the RS-1, the HF-2 are a much better choice than the RS-2 or SR-325i, and probably equal the RS-1. But with a little different presentation - think intimate mids and strong bass of the RS-1 with *flats*, but with the soundstage and crisp treble of the RS-1 with *bowls*.


----------



## smeggy

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_
 I have been listening with HD600s at work for the last few weeks... and I feel it accentuates the Senn's dark side - but this is not at all a bad thing for some types of music._

 

Have you tried the 6n6p yet with the senns, I feel it may perk them up. I have a spare if you'd like it.


----------



## wiatrob

Quote:


  Originally Posted by *HeadphoneAddict* /img/forum/go_quote.gif 
_Wait till you hear my HF-2. If you can't afford the RS-1, the HF-2 are a much better choice than the RS-2 or SR-325i, and probably equal the RS-1. SNIP _

 

Definitely looking forward to trying a pair... 


  Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Have you tried the 6n6p yet with the senns, I feel it may perk them up. I have a spare if you'd like it._

 

I have been stuck on a Raytheon 6GU7 and have been liking the combo with the Senns - I'll revisit the 6N6P though...


----------



## rds

I've found an easy way to ground the pot and chasis of the CTH in the small bom case.

 What you need is a 1/8" 4-40 screw with nut (and preferably lock washer), and 2 ring terminals: one with a 1/4" hole, and one with a number 4 screw hole.

 The 1/4" ring terminal goes between the pot and front panel as shown. Note that the 1/4" ring terminal needs to be screwed on to the shaft like a nut, because it is not quite large enough to just slide over.






 You have a wire that goes from the pot ring terminal to the other end of the board. Here it is clamped into the other ring terminal along with a shorter wire that is soldered to the SG (signal ground) hole on the board.






 This ring terminal is bolted to the chassis and you're done. This configuration still makes it very easy to open and close the case.


----------



## wiatrob

Nice work


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_*This is definitely one my favorite amps of everything I've owned, built, and heard.*_

 

Meant to say thanks for voicing that... It's nice to hear everyone's efforts to bring the amp to fruition are paying off
	

	
	
		
		

		
		
	


	




 Having not built any "bigger"/more expensive designs, it's my fav so far too. For the more practical among us I _think _it _could _be the last one they _need_ to build. But DIY is compelling and other Cavalli & Amb designs are in my future
	

	
	
		
		

		
		
	


	



  Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_I've found an easy way to ground the pot and chasis of the CTH in the small bom case._

 

IIRC I just ran a "local" wire on the pot from its signal ground to under its ring mount. But that's not as idea a ground as the one you've wired.
 BTW Bill & I _may_ soon have something more exciting to replace your fuse holder with
	

	
	
		
		

		
		
	


	




 We'll see...


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_BTW Bill & I may soon have something more exciting to replace your fuse holder with
	

	
	
		
		

		
		
	


	




 We'll see..._

 

That tease should go in the Tweak thread!


----------



## keyid

what value of output resistor are you guys using for grados?


----------



## cfcubed

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_what value of output resistor are you guys using for grados?_

 

No grados here anymore, but I've settled on 100R R18s... Think some are up to 150R or so. Of course this depends on the cans used, source driving level/db and mu/gain of the tube(s) used. E.g. 1/4 vol for 8416 = about 1/3 vol for the 12au7 I pulled this morning, so 8416's mu/gain must be higher...


----------



## wiatrob

100Rs here too - I'll double check next time I get this case open.


----------



## sachu

what resistors do you guys recommend for R18s if someone plans to use the amp with an AKG K701. I don't have the K701 to test out different ressitors..appreciate any input on this.


----------



## rds

100R works great for me with the k701s. I still don't get the knob to 12 o'clock, even with a very quiet source.

 Seems like 100R is just a good all around choice. Works very well for my rs-1, k701, hd650, and gs-1000i.

 With 100R the amp still seems to have more gain than would ever be necessary for any of the above phones, but increasing the output resistance over 100R probably isn't a great idea performance-wise.

 Also, 3 flavors of CTH


----------



## DoYouRight

This is really an interesting amp, will most likely be my first tube build, followed by Bijou or EHHA. Thanks for all the info


----------



## keyid

I tried alot of resistor values from none to 150 using kwame and also like 100 best with senns, but for my new grados I hope to get end of the month im thinking of lowering them. Yes im also itching to build another amp either Bijou, Soha2, EHHA or b22 so many choices.


----------



## rds

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_BTW Bill & I may soon have something more exciting to replace your fuse holder with
	

	
	
		
		

		
		
	


	




 We'll see..._

 

hmmm... is it something to do with R3H 
	

	
	
		
		

		
		
	


	




 ?


----------



## cfcubed

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_hmmm... is it something to do with R3H 
	

	
	
		
		

		
		
	


	




 ?_

 

Oui. And as Bill said if it comes about it'll be in the Tweaks thread...


----------



## Hawdah

Hi gent,

 As you can see, I'm newest on Head-Fi
 Well, I just finished my CTH, and it worked at frist time. I can't give at this moment a serious appreciation about the sound, cause I have't had time to taste others tubes than the one from wiatrob (PS thank for the Caps). It just sound amazing.

 However I've a little trouble concerning my PSU. As it was very hard to find a 220V/24VAC wallwart in Europe I'm using a 25VA/24V toroidal tranformer cased on a same little BoM case with a troggle switch. But when I switch off the power, I have a sorte of "CLOCK" on the can. I"ll appreciate your help to avoid it.

 Thank's


----------



## cfcubed

Quote:


  Originally Posted by *Hawdah* /img/forum/go_quote.gif 
_. But when I switch off the power, I have a sorte of "CLOCK" on the can. I"ll appreciate your help to avoid it._

 

A pretty good, short click in the phones at power-off is normal for this design and nothing to worry about.

 As for most amps w/tubes in them, a pulse happens at power-off & you are hearing the very start of that before the CTH's e12 kicks & releases the relay. I _think_ I measured something like 100mv at the output for a fraction of a second when this happens (not enough to damage headphones).
 This is far less voltage & for much shorter duration than many kinds of headamps that do not have the protection the e12 provides. 
 I just take the phones off my head just prior to power-off.


----------



## Hawdah

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_A pretty good, short click in the phones at power-off is normal for this design and nothing to worry about.

 (not enough to damage headphones)._

 


 That's exactly what I wanted to hear.

 Many thanks


----------



## Billyk

OK it is finally time. Looks like a rainy weekend, it's father's day, and my new solder station arrived last night, all the signs that point to me not having to do any yard work, etc. and being able to spend a little me time. I am going to build the CTH kit that has been calling me for a few weeks now. I am very excited to say the least. I will be sure to post my progress.

 Also, I will need the cap that was changed a few weeks back, if anyone has a spare I would be happy to pay, it would help me avoid a Mouser order that I know I can't afford!


----------



## holland

You can try a local electronics shop and/or a surplus shop. Single caps are pretty cheap.


----------



## Billyk

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_You can try a local electronics shop and/or a surplus shop. Single caps are pretty cheap._

 

Only thing local to me is Rat Shack...
 Thanks, though, I think I have one on the hook.
 For me Mouser is kinda like those warehouse stores, you can save money by shopping there but it always cost more cause you can't help buying more stuff!


----------



## Trapper32

I'm new to the DIY forum but I've been following this and the other CTH thread for a few months now, usually reading them daily if not more often. Amazed at the knowledge and skills that you guys have, far beyond my capabilities. But I was intrigued by this little amp and wondering just how good it really was. Well yesterday I got a package in the mail and found out for myself....I managed to acquire one of rds' builds, the one with the auricaps. 
	

	
	
		
		

		
			





 The build was top notch of course but I wasn't prepared for the sound that came out. You all weren't exaggerating!! I haven't had any experience with really high end amps, mostly entry and mid level, but this is clearly head and shoulders above anything I've heard. I orginally put in my BB 6dj8 ( I'd been collecting various tubes off eBay for a month or so) and WOW...lush lush midrange, tight base and extended highs, great soundstage right off the bat but what floored me was the definition and clarity. And it wasn't subtle either..It was immediately apparent that this is one great sounding amp ...There was no "I think I hear a difference" it was a definite WOW ...Well yesterday was a complete right off...I've been switching tubes and headphones like a kid at Christmas and this thing is SWEET...

 I happened to mention to the wife (who really likes the looks of it) just how amazing it sounds and she quickly retorted "Great, now maybe you can get rid of the others" And you know, altho I hate to admit it, she may have a point... 

 Anyways, I just wanted to thank everyone associated with the development of this, especially to runeight and cfcubed, and to rds for an absolutely stunning build.. This is one amazing piece of kit...


----------



## runeight

Glad you like it!! And you're welcome (from all of us).


----------



## wiatrob

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_Only thing local to me is Rat Shack...
 Thanks, though, I think I have one on the hook._

 

On the way!


----------



## wiatrob

Trapper32 - Happy you have discovered the sonic virtues of this amp. Enjoy!


----------



## cfcubed

Quote:


  Originally Posted by *Trapper32* /img/forum/go_quote.gif 
_The build was top notch of course but I wasn't prepared for the sound that came out. You all weren't exaggerating!! I haven't had any experience with really high end amps, mostly entry and mid level, but this is clearly head and shoulders above anything I've heard. <snip>
 Anyways, I just wanted to thank everyone associated with the development of this, especially to runeight and cfcubed, and to rds for an absolutely stunning build.. This is one amazing piece of kit..._

 

Thanks for the thanks... It's good to hear things like this
	

	
	
		
		

		
		
	


	



 Enjoy!


----------



## sachu

Am sure you guys will be hearing from the folks who will be receiving these soon expressing their regards as well.





 Cheers,
 Sachu

 p.s: my total CTH build comes to 9 with these 5. Took me a good 13 hours to stuff all 5 yesterday.


----------



## wiatrob

It's a little Christmas tree of amps - in June!


----------



## Andrew H

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_It's a little Christmas tree of amps - in June!_

 

Yes, and it will be the proverbial Christmas in July (or even sooner?) for some of us!!!! 

 As long as Sachu can keep up his John Henry routine...


----------



## smeggy

Sachu is a madman on speed!


----------



## Billyk

Quote:


 Took me a good 13 hours to stuff all 5 yesterday. 
 

Well I finally started my build. Been about 12 hours so far and I just have the resistors and diodes completed. Been double and triple checking, not my usual methodology, but everyone says take it slow... so slow it is. It's really hard to wait though.


----------



## sachu

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_Well I finally started my build. Been about 12 hours so far and I just have the resistors and diodes completed. Been double and triple checking, not my usual methodology, but everyone says take it slow... so slow it is. It's really hard to wait though._

 

My method was to stuff all components for 3 boards at a time so thery are all uniform and am not looking at the BOM and silk printout every time i put in that ressitor on a board. It is handy to populate them all together..saves a bunch of time for sure.


----------



## Billyk

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_My method was to stuff all components for 3 boards at a time so thery are all uniform and am not looking at the BOM and silk printout every time i put in that ressitor on a board. It is handy to populate them all together..saves a bunch of time for sure._

 

I am sure it does!
 I usually knock stuff out fairly quickly, but this is a really dense board to say the least. I am finding it very enjoyable and the concentration relaxing. I put a Dead show on, plug in my IEMs and I'm good to go.
 Darn, this is way to much fun!


----------



## Forte

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_Been double and triple checking, not my usual methodology, but everyone says take it slow... so slow it is. It's really hard to wait though._

 


 It is hard to stress the slow and steady approach enough, most, if not all problems have been caused by components in the wrong spot or the wrong orientation(diodes especially). Extra time now will be time well spent if you can avoid having to do any troubleshooting, there is not much room if you have to start probing around and desoldering parts on such a tightly packed board is no fun.

 It will be well worth the wait when you finally get to hear it!


----------



## wiatrob

Quote:


  Originally Posted by *Trapper32* /img/forum/go_quote.gif 
_ ... I haven't had any experience with really high end amps, mostly entry and mid level, but this is clearly head and shoulders above anything I've heard. I orginally put in my BB 6dj8 ( I'd been collecting various tubes off eBay for a month or so) and WOW...lush lush midrange, tight base and extended highs, great soundstage right off the bat but what floored me was the definition and clarity._

 


 Trapper - please share more of your tube impressions when you get a chance:

http://www.head-fi.org/forums/f6/cav...thread-417322/


----------



## Ynis Avalach

Is there anyone out there who has screened the leads of C4R and C4L? And if how?
 Screen must be connected to SG, or not?
 Greetz Ava


----------



## TimJo

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_I put a Dead show on, plug in my IEMs and I'm good to go.
 Darn, this is way to much fun!_

 

I like your technique!


----------



## cfcubed

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_Is there anyone out there who has screened the leads of C4R and C4L? And if how?
 Screen must be connected to SG, or not?
 Greetz Ava_

 

IIRC keyid shielded his C4 leads (see CTH Tweaks thread a couple/few pages back about caps). Think its usually found unnecessary, esp if you keep the leads as short as possible. Shield would just go to ground plane / SG.

 Are you experiencing a problem that you think screen/shield would fix?


----------



## Ynis Avalach

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Are you experiencing a problem that you think screen/shield would fix?_

 


 No, but the shield is already on the leads, but thank you anyway.


----------



## keyid

nice s/g, I have s/o on the CTH they sound great. My leads are about 6" long and covered in copper, I would get humming otherwise.


----------



## Ynis Avalach

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_nice s/g, I have s/o on the CTH they sound great. My leads are about 6" long and covered in copper, I would get humming otherwise._

 

Sadly this beatiful bonnet from wiatrob won't close now.
	

	
	
		
		

		
		
	


	



 I know those s/g are massive overkill, I didn't wanted them in the first place, but because I order some meters of the s/g cable there was confusion in the shop and they ordered s/g. Damn those caps are expensive! If this goes on like this my cth will cost more than my b22 built!
	

	
	
		
		

		
		
	


	




 How did you stuff this all in one case, did you use the BOM case, I've got the 16" standard hammond?


----------



## wiatrob

Ynis - there may be some European Head-fi'ers who'd take the caps off your hands.

 I imagine they are like Russian teflons - too big to fit in the case. The obligatos were the biggest i could squeeze into the BoM case and get the lid on.

 I got my loaner build back (Thanks Naamanf!) and put some horizontally mounted Soniccap GenIIs in. Burning in now...


----------



## cfcubed

Reviews/comments seem to favor Auricaps too... They are the largest I've seen that seem to fit in BoM case.


----------



## keyid

actually mines not cased yet and the caps are hanging in the air. Im still modifying the CTH and probably going to casing in a larger box. I was thinking of cutting two holes so that the caps are halfway exposed.


----------



## Ynis Avalach

Here's finally my go at the CTH:
http://www.head-fi.org/forums/f6/pos...ml#post5800827


----------



## Ynis Avalach

I don't know if it's a problem, but this is my first tube project, so I thought better do it right.^^

 Everytime I power up my CTH with a Tungsram ECC82 the tube lights up like a light bulb, not extreme, but quite bright. Is this something to worry about?
 Everything seems to work otherwise. It sounds terrific!

 Any help much apreciated!
 Greetz Ava


----------



## tacitapproval

Have you measured the heater voltage?


----------



## runeight

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_I don't know if it's a problem, but this is my first tube project, so I thought better do it right.^^

 Everytime I power up my CTH with a Tungsram ECC82 the tube lights up like a light bulb, not extreme, but quite bright. Is this something to worry about?
 Everything seems to work otherwise. It sounds terrific!

 Any help much apreciated!
 Greetz Ava_

 

Does it only do this when it first turns on? Or does it stay this way continously?

 If just at startup, this is normal for many European tubes.


----------



## Ynis Avalach

No just for the first halt of a second and then darkens during one second.
 Heater voltage is perfectly fine.
 Thank you!


----------



## cfcubed

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_No just for the first halt of a second and then darkens during one second.
 Heater voltage is perfectly fine._

 

Great. Glad to hear _*"It sounds terrific!"*_ too. That's a nice looking build there (neatness of wiring, etc) and some monster C4 caps
	

	
	
		
		

		
		
	


	




 BTW, I _think _when I noticed this < 1 sec of brightness at power on for some tubes I found it was the LED below the tube, not the filament itself.


----------



## keyid

Quote:


  Originally Posted by *Ynis Avalach* /img/forum/go_quote.gif 
_No just for the first halt of a second and then darkens during one second.
 Heater voltage is perfectly fine.
 Thank you!_

 

As runeight says, some tubes flash brightly when they turn on.


----------



## olblueyez

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_As runeight says, some tubes flash brightly when they turn on._

 

The bright flash is standard procedure for some tubes. I have no idea why.


----------



## smeggy

Mine does that flash too


----------



## Ynis Avalach

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_BTW, I think when I noticed this < 1 sec of brightness at power on for some tubes I found it was the LED below the tube, not the filament itself._

 

No in this case it's the heater connected to pin 4.
 Thank you all!
 btw:all this wiring and screening C4's wires took most of the time, but I think it looks beautiful and I've no problems with hum, or noise (yet, haven't tried 6H6Pi)


----------



## nux

The flash is from a small bit of thin filament with a low resistance when cold, when heater voltage is applied a large inrush current goes through, the small filament heats up quickly (flashes), increasing in resistance which then allowing the main heater to warm up with the current stabilising.


----------



## nsx_23

I haven't kept up with the CTH thread for a long time, but are the full kits with custom panels available now??? 

 Uni holidays, so I'm itching to build something


----------



## tacitapproval

Sure, see here: 
CTH


----------



## nsx_23

And I take it the tube holes are drilled as well???

 I suck at caseworking, so yeah...


----------



## holland

yes, it's optional (upgrade).


----------



## wiatrob

nsx_23, it does seem like you are missing a tube amp in your stable!


----------



## sachu

3 brand spanking new CTHs tested and ready


















 They all feature Janzten audio 0.22uF crosscaps for the coupling caps.
 The middle one in the long case has preouts and a shunted ALPS RK27, while the leftmost small one has a mini out which is switched by the neutrik1/4 inch jack.

 The 4th one needs an inductor and the 5th one (mine) needs a splitter section transplant
	

	
	
		
		

		
		
	


	




.


----------



## Forte

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_3 brand spanking new CTHs tested and ready to be shipped to their new owners.. 

 They all feature Janzten audio 0.22uF crosscaps for the coupling caps._

 


 Very nice. How do the Jantzen crosscaps compare to other coupling caps you have tried?


----------



## holland

that's alot of builds. are you selling them? just curious as to why you build so many.


----------



## wiatrob

Sachu is the number one builder of CTHs, now beating out NUX, who was off to an early lead!


----------



## sachu

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_that's alot of builds. are you selling them? just curious as to why you build so many._

 

They were built for friends..a couple of them are for HFers. Only charged them parts cost. Kabeer and Andrew_H are among them. I just couldn't let Kabeer run the Yamaha YH-1000 with a mini3. 
 Andrew_H, manager of Maximo Products has been a steady supporter and sponsor of our local Portland HF meet chapters.
 So when he asked me if I could build him one at Canjam last month, I couldn't turn him down.


----------



## holland

That's cool. It sounds like you've got quite a crew there.

 I also noticed you seem to be moving into the esoteric headphone area. Aren't you a grad student? I think I'm missing out on something, you have more money than I do! I thought students were broke! I've been planning to buy the ESP-950 for years, but keep building amps instead and spend all my money on amps. I should probably stop for a while and buy some headphones!


----------



## smeggy

heh, I was the other way around, loads of phones and no decent amps.


----------



## wiatrob

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_*SNIP
*I should probably stop for a while and buy some headphones!_

 

Funny how the 'usual' hifi rules are turned on their side in this hobby (spend most of your money on the _speakers_) Bet like me, all your amps are _EXCELLENT_


----------



## sachu

Just finished a splitter section transplant on CTH #9 (mine)..have Dayton caps in them and a shunted ALPS RK27.
 It is going to make a trip up to Canada to John E Woven on loan for a month..sigh..going to be without a CTH for a little while longer 
	

	
	
		
		

		
		
	


	




.

 The other CTH (#8) is waiting for the L1H inductor before i can case it up though the case work is done.


----------



## sachu

I also have a pair of Obbligato caps on the way to try out in the CTH.


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Just finished a splitter section transplant on CTH #9 (mine)_

 

Nice work but you must know you cannot stop at 9 you *must* build at least one more to make it 10. 
 Maybe your 10th can have a medium-sized knob


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Maybe your 10th can have a medium-sized knob
	

	
	
		
		

		
		
	


	


_

 

Let me know if you want me to toss one in your next care package, Sachu!


----------



## zkool448

sachu, you're a machine!


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Let me know if you want me to toss one in your next care package, Sachu! 
	

	
	
		
		

		
		
	


	


_

 

you guys are evil i tell you...bah.. go ahead and drop one in 
	

	
	
		
		

		
		
	


	




..throw in a couple of noval sockets in as well please.

  Quote:


  Originally Posted by *zkool448* /img/forum/go_quote.gif 
_sachu, you're a machine! 
	

	
	
		
		

		
		
	


	


_

 

one that is burnt out ..nearly. need to sit back and chill dude..


----------



## wiatrob

sachu;5853192
 one that is burnt out ..nearly. need to sit back and chill dude.. [img said:
			
		

> http://www.head-fi.org/forums/images/smilies/beerchug.gif[/img]


 
 Maybe listen to a little music?


----------



## smeggy

he doesn't have time for music.... build moar amps dammit!!!


----------



## wiatrob

Guess who's having problems with a CTH build! Moi!

 I built up another unit for this weekend's meet. The PS is having an issue:

 The trafo buzzes loudly - then the amp blows a fuse (up to 1.5A) or shuts down the wall wart thermal trip after ~5 seconds (the 24V comes up, the Heater is 12.7V,
 the plate voltage gets to ~65 then, poof. 

 I've verified all component values and orientations. I've replaced the 24V reg and TLE24.

 My next suspicions are the splitter Q's and the Multiplier Q's... Anybody?


----------



## runeight

There has to be a short or near-short somwhere. And if that kind of current is flowing through any of the splitter transistors they were fried a long time ago.

 Is this with or without tube?


----------



## aphexii

This may be out of left field (and well i'm half asleep so my brain isn't fully working), but how hard would it be to get this thing battery powered?


----------



## wiatrob

Without tube. I have looked at all the solder joints for bridges and they look good. haven't done a component by component check yet - but I would think that _something_ would be getting warm or smoking and there is no evidence of that.

 I even get the e12 LED lighting.

 C1L WAS in backwards, briefly, but didn't pop and has been replaced...

 I may build up another and wait to troubleshoot this one after the meet.


----------



## rds

Quote:


  Originally Posted by *aphexii* /img/forum/go_quote.gif 
_This may be out of left field (and well i'm half asleep so my brain isn't fully working), but how hard would it be to get this thing battery powered? 
	

	
	
		
		

		
		
	


	


_

 

Unless you want to use 2 truck batteries this amp isn't going to run long.


----------



## pinkfloyd4ever

Quote:


  Originally Posted by *rds* /img/forum/go_quote.gif 
_Unless you want to use 2 truck batteries this amp isn't going to run long._

 

that sounds like a dare around these parts...


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I've verified all component values and orientations. I've replaced the 24V reg and TLE24.

 Without tube. I have looked at all the solder joints for bridges and they look good.

 C1L WAS in backwards, briefly, but didn't pop and has been replaced...

 I may build up another and wait to troubleshoot this one after the meet._

 

Heh, I had my problems as well right before the NY Spring meet - To be sure I got it going I just replace a bunch of sand.

 As runeight says, there are not many parts in the amp that will cause that kind of draw & not burn or pop (thereby reducing the draw to below normal).

 Your build check statements point to a bad part, but my guess would have been reversed diode or reg... Something early in the PS. I'd re-review & check from the 1st PS sand components back all the way to wallwart. 

 I'm w/runeight - would think only something like a short would cause & handle that kind of draw for more than a second & it would only happen once.


----------



## cfcubed

Quote:


  Originally Posted by *aphexii* /img/forum/go_quote.gif 
_This may be out of left field (and well i'm half asleep so my brain isn't fully working), but how hard would it be to get this thing battery powered? 
	

	
	
		
		

		
		
	


	


_

 

A re-design... Need A/C for HV multiplier & 30VDC minimum for LV & heater. Tube heater alone draws 4W or so & that's heavy. Best to look elsewhere.


----------



## wiatrob

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Your build check statements point to a bad part, but my guess would have been reversed diode or reg... Something early in the PS. I'd re-review & check from the 1st PS sand components back all the way to wallwart. _

 

That's what I thought too - all the diodes are correct. I'll swap the 2595 (even though it's putting out proper voltage), test the diodes and trace through the PS.


----------



## cfcubed

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_That's what I thought too - all the diodes are correct. I'll swap the 2595 (even though it's putting out proper voltage), test the diodes and trace through the PS._

 

Hey, just prior to doing that you could try lifting the load/output pins of the 24V & 2595 & using an ammeter from the pins to where they connect on PCB. 

 The stable draw of a CTH is usually not more than 1/2 an amp (12 watts) or so. Current draw on heater reg should be about tube heater spec (.4A?).
 IIRC the LV reg draws around 6/7 watts throwing off 50%-> 60% in heat, so maybe supplying 3&1/2 watts (< 0.15A) or so? 
 HV shouldn't draw much at all. Could also lift input legs & see what the reg are drawing. Note: all of these are rough numbers off the top of my head
	

	
	
		
		

		
		
	


	




 But seem like nearly 1A @ 24 VAC is being consumed _somewhere_ and that's an awful lot. By measuring load about the regs we can split the problem to 1) prior or 2) post regs.


----------



## sachu

wiatrob, Suggest you do what runeright asked me to do long back when I had such problems with my proto build.

 Remove the 24V regulator. 

 TUrn on the amp and see if any of the PSU components fry. Check for voltage at input of voltage regulator, should be about 32-34 volts.

 If that seems to be fine then remove all the splitter transistors except for the TLE2426 splitter IC.
 Put the regulator back in its place and turn on the amp again. Check to make sure the output of the ground splitter IC is reading 12 volts and its input is reading 24 volts.

 If that is right, then install the rest of the splitter silicon and give it a try. The amp should work then.

 If not, then the problem is with the buffer transistors.

 Thsiis the process I have followed for 4 of my builds that gave me problems.
 It has always been the splitter that needed to be replaced even though I had messed up the PSU in one build. That amp wouldn't work until i replaced the splitter section.


----------



## wiatrob

Mea Culpa. I don't listen to my advice to triple check things very well. Thanks all for the input and the edifying troubleshooting reminders. 
 There were no diodes in UPSIDE DOWN. but one WAS backwards - you called it Sachu.

 Fixed it and the e12 trips. Checking voltages now...

 I have even deeper respect for Sachu and Nux - you get a little crosseyed building multiple CTHs...


----------



## wiatrob

All voltages are SPOT ON (12V measurements are within 10mV of each other!)

 Playing beautiful music. This amp _will _be at the meet Saturday.


----------



## sachu

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Mea Culpa. I don't listen to my advice to triple check things very well. Thanks all for the input and the edifying troubleshooting reminders. 
 There were no diodes in UPSIDE DOWN. but one WAS backwards - you called it Sachu.

 Fixed it and the e12 trips. Checking voltages now...

 I have even deeper respect for Sachu and Nux - you get a little crosseyed building multiple CTHs..._

 

heh...i've learned it the hard way my friend. lost a transformer before I grew a brain and put a fuse in there 
	

	
	
		
		

		
		
	


	




.

 Edit: awesome !! 
	

	
	
		
		

		
		
	


	




 Now get to work on my EHHA perf top so I can get my stuff going here.


----------



## wiatrob

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_heh...i've learned it the hard way my friend. lost a transformer before I grew a brain and put a fuse in there 
	

	
	
		
		

		
		
	


	




._

 

Fuses saved a lot of rework here... Russian K42 PIOs, Alps RK27, 1/4"out, front panel Red LED, Orange tube uplight. Socketed R3H for alternate/alternate heater values (currently 6.3V).



 I'm on the perf top...


----------



## sachu

Nicely done Bill...been meaning to try out those Russian PIOs but they are all sold in lots of 10 or 20 which is wasteful.

 should have my obbligatos soon as well.

 Btw, definitely try out the 6CG7/6FQ7.


----------



## wiatrob

I've had a 6CG& clear top for a while - didn't you see my posts. 
	

	
	
		
		

		
		
	


	




 I'll drop some PIOs in your care package, should be off this week.


----------



## wiatrob

More kind words for the CTH:

http://www.head-fi.org/forums/f45/co...ml#post5882795


----------



## sachu

umm Bill... my EHHA perf top?


----------



## wiatrob

'Twas the care package I mentioned. It's right in the middle of my bench so I won't postpone any longer...


----------



## wiatrob

Just snarfed' this (MID-FI?
	

	
	
		
		

		
			





) :

 "CTH: I'm actually listening to one as I'm typing this up. I only have low impedance phones these days, but this little guy is a KILLER with low impedance. It's at least mid-fi, not lo-fi. I'll have to compare it to a CK2III sometime."

 from the NorCal Impressions

 EDIT: anybody know who's CTH it was?


----------



## holland

looks like the poster's, built by sachu. i completely spaced on this meet. i really wanted to hear the hd800 and hf2. oh well.


----------



## wiatrob

Quote:


  Originally Posted by *holland* /img/forum/go_quote.gif 
_
 The + and - are taken from the same side (1 ground for that side). The DC on that one side should be offset within itself by the + and -. G is not attached, so the DC floats.

 I guess a more apropro situation is this (and less confusing though they are the same), with the M3.




_

 


 Your supposition was correct, Holland.... 
	

	
	
		
		

		
		
	


	




 [size=xx-small]Balanced CTH proof of concept.[/size]


----------



## wiatrob

It's already known that this design can be used as a 'tube tester' - a balanced version can be used as a 'tube comparator.' I actually have a 6N30 in one channel and a 12BH7 in the other right now

 Completely gratuitous I know. If only my ears matched!


----------



## smeggy

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_It's already known that this design can be used as a 'tube tester' - a balanced version can be used as a 'tube comparator.' I actually have a 6N30 in one channel and a 12BH7 in the other right now

 Completely gratuitous I know. If only my ears matched!_

 

Ah, a man after my own heart... 
	

	
	
		
		

		
		
	


	




 Post details plz 
	

	
	
		
		

		
		
	


	




 Oh, and how's the 6n30?


----------



## wiatrob

The 6N30 remains one of my favorite tubes for this amp - plentiful and tight bass. The 12BH7 gives it a run for the money. 

 I'll post some build details soon, pretty straightforward though - almost exactly as in the M^3 diagram above. I have flaoting SG (case no case) and tied OG's from board to board. (My OG->SG V's measure within a few mV...)


----------



## Ged

I have just completed my cth and initially all the voltage readings were correct and the e12 functioning correcctly. After checking for a second time and messing around I believe some thing must have shorted. Corrently the e12 is not working and readings are as follows

 ORand OL are 0V
 OG is 12 V
 heater 12V
 TB+ is 110V
 V across pins 1 and 6 is 0

 Any help would be much appreciated but please keep it simple as I am a complete novice


----------



## sachu

Seems like Q4P and Q3P might be dead. Can you check the voltage at the emitter of Q4p and Q3P with respect to SG?


----------



## wiatrob

Welcome, but a sad first post! To double check, OR and OL measured from the pads on the PCB or the output jack?

 When you are measuring pins 1 and 6, are these are measured from SG to pin 1 and SG to pin 6?

  Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_I have just completed my cth and initially all the voltage readings were correct and the e12 functioning correcctly. After checking for a second time and messing around I believe some thing must have shorted. Corrently the e12 is not working and readings are as follows

 ORand OL are 0V
 OG is 12 V
 heater 12V
 TB+ is 110V
 V across pins 1 and 6 is 0

 Any help would be much appreciated but please keep it simple as I am a complete novice_


----------



## sachu

I have had two CThs come back to me with issues. 

 1>One CTh suddenly seems to have stopped working. All voltages except for OR->SG, OL->SG seem to check out fine.
 THis amp had 250 hour on it at least.
 Only had time to take it apart oday..will poke around a bit more to see what's up with this amp, see what voltages are there on the splitter and the buffers and of course on the E12. (Dayton audio caps for C4R and C4L, with shunt modded alps Rk27)

 2> The second CTH seems to be tripping whenever i go beond 2 o clock position on the volume knob. Need to figure out why.. (Jantzen audio caps for C4R and C4L)


 Any ideas?


----------



## Ged

can you please tell me which one is the emitter?

 wiatrob-OR andOL tested on pads
 pins 1 and 6 tested with aprobe on each and tube fitted as described on cavalli.com


----------



## sachu

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_can you please tell me which one is the emitter?

 wiatrob-OR andOL tested on pads
 pins 1 and 6 tested with aprobe on each and tube fitted as described on cavalli.com_

 



 Did you test across pins 1 and 6, i.e with the red lead on pin 1 and black lead on pin 6.
 Or with the red lead (positive) on pins 1 and 6 and the black lead (ground lead) on SG on the board?


----------



## Ged

red on pin 1 , black on pin 6 tube fitted


----------



## sachu

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_red on pin 1 , black on pin 6 tube fitted_

 

Ok..that will give you 0 V as pin 1 and 6 are supposed to be at the same voltage potential.

 Remember to measure all voltages with respect to SG. That is if you want to measure voltage on pin1 of the tube socket. PLace the red lead of the multimeter probe on pin1 and the black lead on SG (on the board). This will give you thevoltage at pin1. Then do the same for pin6.

 OL and OR are similar as well...i.e red lead on OL/OR and black lead on SG.


----------



## Ged

pin 1 voltage relative to SG 108v
 pin 6 voltage relative to SG 108v


----------



## sachu

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_pin 1 voltage relative to SG 108v
 pin 6 voltage relative to SG 108v_

 

That is without the tube i trust? If so then that's fine...a bit to the higher side but still within spec.


----------



## Ged

yes taken with the tube removed directly from the top of the socket


----------



## wiatrob

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_can you please tell me which one is the emitter?_

 

The pins connected to C13P (Q4P) and C14P (Q3P).


----------



## Ged

Q4P and Q3P emitters are at approx 105V relative to SG


----------



## wiatrob

That's good. But I think we actually knew that from the plate B+ pin measurements. I am suspecting the buffer devices. 

 When you say the e12 doesn't work, do you mean that the e12 red LED comes on and stays on, correct?

 Also, please double check all your solder joints and pads for bridges or clinging wire trimmings. Might be as sinple as a bad joint knocked loose during measuring.


----------



## Ged

Yes the LED comes on red and stays that way unlike when it initialy worked


----------



## runeight

I suspect the buffers too. Ged what is the voltage at pins 1 & 6 with respect to SG when a tube is inserted?

 Let's get this measurement settled and then we can work on the buffers. Since OG seems to be correct we think buffers.

 However, OL and OR are only hooked up to the output devices when the e12 is on. To see what's happening with the buffers we'll need to make some internal board measurements. When you're ready.


----------



## runeight

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I have had two CThs come back to me with issues. 

 1>One CTh suddenly seems to have stopped working. All voltages except for OR->SG, OL->SG seem to check out fine.
 THis amp had 250 hour on it at least.
 Only had time to take it apart oday..will poke around a bit more to see what's up with this amp, see what voltages are there on the splitter and the buffers and of course on the E12. (Dayton audio caps for C4R and C4L, with shunt modded alps Rk27)

 2> The second CTH seems to be tripping whenever i go beond 2 o clock position on the volume knob. Need to figure out why.. (Jantzen audio caps for C4R and C4L)


 Any ideas?_

 

Sachu, what is the status of this?


----------



## Ged

V relative to SG with tube inserted is 78V on pins 1 and 6


----------



## runeight

OK. That's the right voltage.

 We need two more measurements. R18L and R18R with respect to SG. Please measure each lead of each resistor to SG. Four measurements.


 These will be a bit tricky to get, but they will tell us what the buffers are doing.

 And is OG still at 12V with respect to SG?


----------



## Ged

OG is still 12v
 r18r is 0.6 v and 0.6v
 r18l is 11.9 v and 11.9v


----------



## runeight

Thanks. This means that the left channel is ok but the right is not.

 I hate to go to the next step, but this will be replacing Q8R and Q9R. If this doesn't fix the problem we'll have to replace the other transistors in the right buffer. But start here.

 However, before you do this please check all the resistor values in the right buffer and make sure that the opamp IC1 is really a dual opamp (TL082) and that all of its pins are seated properly in the socket.


----------



## Ged

checked your suggestions all ok
 I will have to order parts for the first step but I have the other transistors on hand if we need them.
 I am in absolute awe of your ability to come up with a solution and such fast responses many thanks (just keep your fingers crosssed)

 Gerard


----------



## runeight

Thanks. We'll wait for you to get the new O/P transistors and hope that this fixes everything.


----------



## runeight

Ged, one more thing. Have you checked to see that on the right channel you have the PNP (BC327) and NPN (BC33y) devices in the correct locations? Have you checked the polarity of the other transistors on that channel?


----------



## Ged

I am pretty sure they are alright Judging by the meticulous way I put the board together. I think you may have missed my first post,the amp did initially work.It was after wards that I believe I caused a short that it stopped working


----------



## runeight

OK. Sorry about that. I guess we replace transistors until it works.


----------



## holland

for the most part you can test transistors in circuit as if they were diodes. I think I have a post about that in this thread. Differences between NPN and PNP and pay attention to shorted paths using the circuit diagram and you can narrow down the exact transistor.

 Transistor replacement on the CTH is a joy. When things short, the most likely culprit are the actual output transistors. They are on the edge of the board and easy to test.


----------



## wiatrob

GED, I think your kit shipped with extra buffer transistors - let me know if you need some more and I will send them your way...


----------



## Ged

Thaks wiatrob 
 you sent me some BC550,s and some BC569s which may be required
 Igot some bc327 and bc337 as required for the repair here in the UK for £2 shipped just to save time


----------



## cfcubed

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_I have just completed my cth and initially all the voltage readings were correct and the e12 functioning correctly. After checking for a second time and messing around I believe some thing must have shorted._

 

Ged - Later, after you have your CTH working again, you might find it a bit funny reading runeight's sig & the quote above
	

	
	
		
		

		
		
	


	




 Note that I too broke one of my CTHs causing a short while taking measurements in the output buffer area. Searching for CTH trouble-shooting posts by holland, runeight, etc & the info here should narrow down the problem. IIRC in my case I replaced all the BC devices in OB & that fixed it.

 Back in the proto days I'd a lot of practice pulling & replacing TO92s
	

	
	
		
		

		
		
	


	




 Using PCB vise, used a solder blob floated among 3 pins, pulled 'em then used solder vac to remove excess. Desoldering braid might sub/help too.

 Good luck. You'll get a bit more DIY, learning & practice than you expected but the end result will be worth it.


----------



## Ged

I will bear in mind the solder blob idea if I have to replace the rest of the BCs on the right channel (the 2 I took out this morning were a right pain in the ar**)


----------



## Forte

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_I will bear in mind the solder blob idea if I have to replace the rest of the BCs on the right channel (the 2 I took out this morning were a right pain in the ar**)_

 

Another easy way is to cut the leads off under the transistor body and remove the leads one at a time. This assumes of course that you do not need to reuse it!


----------



## blaken

I ran across this transformer and was wondering if it would make a suitable power supply for the CTH. It looks like it is 26.2VAC but I am still waiting on a data sheet from the manufacturer. It is probably extreme overkill but I have it already and thought it might be fun to make a separate psu.

 Does anyone have any tips on what I need to do to get it to work with a CTH.


----------



## cfcubed

Quote:


  Originally Posted by *blaken* /img/forum/go_quote.gif 
_ < snip > It looks like it is 26.2VAC but I am still waiting on a data sheet from the manufacturer. It is probably extreme overkill but I have it already and thought it might be fun to make a separate psu.
 Does anyone have any tips on what I need to do to get it to work with a CTH._

 

Looking for 24VAC w/min. 0.7A or so input for CTH. 24VAC .8A+ adapters are around for like $12-$20.

 But as you've that 26VAC around, if one of its windings meets the load req.s you would likely be able to use it directly. IIRC one of my 24VAC/1.25A adapters maintains 26VAC into CTH under load. But may need to check/improve heater & LV/24 reg heatsinking as they'll need cope w/higher input Vs.


----------



## runeight

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_Thaks wiatrob 
 you sent me some BC550,s and some BC569s which may be required
 Igot some bc327 and bc337 as required for the repair here in the UK for £2 shipped just to save time_

 

Ged, please make sure that these are the "25" class hfe for these devices. If they are mixed class or a different class you still might have problems.


----------



## blaken

Thanks cfcubed, It looks like I can get a 24v AC wall wart for less then the cost of the case to put that transformer in. I will just hang onto it.

 What are the exact dimensions of the board from spruce canyon? I might try to cram in a tangentsoft crossfeed into the 1602 case but I want to make sure it is going to fit first.

 Also would there be a noticeable SQ improvement if I used the ALPS RK27 over the RK097 in the standard BOM?

 Thanks guys.


----------



## Ged

I have just finished replacing all the transistors and still have problems
 The V on R18R is still wrong currently 23.5V
 I believe one of the parts was 40 class
 The second phase of the repair were from bills I am sure they are alright


----------



## sachu

Quote:


  Originally Posted by *blaken* /img/forum/go_quote.gif 
_
 Also would there be a noticeable SQ improvement if I used the ALPS RK27 over the RK097 in the standard BOM?

 Thanks guys._

 

RK27 with a shunt mod sounds significantly better to me over the RK97 to me.


----------



## blaken

Thanks for the tip.

 I found this article about shunt modding Shunt Pot Volume Control - World-Designs-Forum

 Did you use a 47k metal film resistor?


----------



## sachu

with a 50k ALPS pot..47k works very nicely.


----------



## smeggy

That's how mine is set too up except mine has 52k resistors (that's what was on hand) and it is a good improvement over a standard cheap pot.


----------



## runeight

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_I have just finished replacing all the transistors and still have problems
 The V on R18R is still wrong currently 23.5V
 I believe one of the parts was 40 class
 The second phase of the repair were from bills I am sure they are alright_

 

Ged, are the voltages at OG and R18L still ok (with respect to ground)?

 Edit to say R18L not R19L.


----------



## Ged

all other volages are still ok
 could it be the wrong class (40) part in Q8R be the problem I have ordered a repacement


----------



## Billyk

Another one lives! 
 Sounds swell, using the 6BQ7A that Bill shipped with the kit. Can't wait to get rolling!
 The regulator gets quit hot, can't put my finger on it for more than 2 seconds. Using a 1.6 amp power supply. Is this ok?


----------



## runeight

Congratulations!!! Enjoy the tube rolling.

 It's hard to say exactly how things will go but it is true that the 1.6A wall wart is likely to put a higher voltage across the regulator and to increase its power dissipation. If you plan to stay with this setup I would recommend putting a small finned heatsink onto the regulator. You'll have to bend the fins a bit, but others have done this.

 Others here can suggest a good part number to use.


----------



## Ged

runeight do you think that replacing Q8R with the correct class of transistor will solve the voltage problem


----------



## runeight

It IS possible depending on how different the hfe in the class 40 device is from the other class 25 output transistor in the buffer. It should be done anyway so that, if there is still a problem, we can elminate this as a source of the problem.

 This eventually has to work. Don't give up!!!


----------



## Ged

I will keep on going but I find your replies reassuring THANKS


----------



## Billyk

I does have a heatsink on it that is why I am concerned. It is about 28vac unloaded so I am sure the reg is working harder than it has to and the extra has to go somewhere. The specs state 24VAC 1.6 amp. I'll have to find something closer to the ideal or figure out how to sink it better. I have a variac, maybe that will help.
 Sounds great but I have begun to notice that the left channel will distort the bass if turned up to much. It is not noticeable generally but definitely there. I only had the one tube with me so will check that first. Any idea where I should start if it is not the tube?


----------



## runeight

28VAC will yield close to 38V at the first filter cap and slighly less than that into the regulator. The design spec is for 32VDC into regulator. You are likely to have aroune 36V. This is quite a lot more power and it is probably correct that the small heatsink there now cannot do the job.

 It's hard to say about the distortion. I don't recall hearing about this type of issue before, but a tube change is a good thing to try. However, I suspect that this will not fix the problem I wonder if this could be related to some of the issues you had earlier with hum, etc?

 If not the tube, we'll have to inspect the buffers to see what their operating points are.

 To make a start, measure the voltages on all of the tube pins with respect to SG. And measure all of IC1 (buffer opamp) pins with respect to SG too. This will tell us a lot. Be careful not to short anything. As you know replacing parts is a tight squeeze.


----------



## Billyk

OK to start I have a more sane supply. 24.4VAC unloaded. It is spec'd at 20v 1amp. Things are cooler for sure I can hold my finger on the reg heatsink now and it's moderately hot just a bit more than warm, so I think things are good there. I changed the tube out, the plate voltages changed from pin1 90v pin 6 81.6v to what I put down below. I also changed the output jack and wiring. I know I changed a lot at once, not the best for troubleshooting
	

	
	
		
		

		
		
	


	




 I cannot recreate the bass distortion and e-12 activation... Hopefully things are better!!
 My measurements as requested.
 Tube:
 1- 78
 2- 0
 3- 1.7
 4- 6.0
 5- 0
 6- 78.4
 7- 0
 8- 1.6
 9- 0

 IC1
 1- 7.5
 2- 11.9
 3- 11.9
 4- 0
 5- 11.9
 6- 11.9
 7- 5.4
 8- 24

 Tube = 6BQ7A


----------



## Billyk

I just discovered as I was swapping out tubes. It is the tube causing the problem. The others I tried did not cause any trouble, put the original one back in and there it was!


----------



## runeight

There have been occasional reports of failures to Q1P. After some investigation we are pretty sure that this happens in builds where the area around the 24V regulator (where Q1P is) is not ventilated well enough. Because the regulator gets really hot the ambient temperature in the area around the reg gets fairly high.

 If any of you experience Q1P failures replace this transistors (BC550C) with one of the BC337-25 transistors as used in the ouput stage. The BC337 is a higher current, higher wattage transistor that should be more comfortable in the hot spot around the regulator. This will not, however, make the LV ps immune to direct shorts at the output of the regulator. In this case Q1P will blow protecting the other components in the system.

 If you're not having problems there is no need to make this change.

 The Cavalli Audio website has been updated as well as www.sprucecanyonlabs.com. 

 All kits from Spruce Canyon will now come with the BC337 instead of BC550C for Q1P.

 Thanks to those builders who helped to locate this problem and to cfcubed for helping to diagnose it.


----------



## wiatrob

All kits will now come with Q1P = BC337, and two complete sets of BC550/560s and BC327/337s


----------



## cfcubed

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_If you're not having problems there is no need to make this change._

 

BTW, the symptom I had was, 30 secs after pwr-on, e12 would go "green" for a minute or so then drop out ("red") until CTH was unplugged & allowed to cool. Both input & output of 24V reg measured below normal when exhibiting the condition. CTH had 50 -> 100 hrs on it & was not as well-ventilated as SCL kits. My original CTH (avatar) w/far more hrs has not exhibited this problem.
 One of sachu's CTHs developed similar/related issue w/Q1P. 

 So if a problematic CTH's 24V supply reads low, suspect Q1P & replace w/BC337.


----------



## Ged

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_It IS possible depending on how different the hfe in the class 40 device is from the other class 25 output transistor in the buffer. It should be done anyway so that, if there is still a problem, we can elminate this as a source of the problem.

 This eventually has to work. Don't give up!!!_

 

Well I have good news and bad news
 Repacing q8r has corrected the voltage problem.The voltage at r18r is now 12V approx and all other voltages ok

 The problem now is that even though the LED is turning green there is no switching noise from the relay and no voltage on OR and OL

 But at leaast we are making progress


----------



## sachu

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_Well I have good news and bad news
 Repacing q8r has corrected the voltage problem.The voltage at r18r is now 12V approx and all other voltages ok

 The problem now is that even though the LED is turning green there is no switching noise from the relay and no voltage on OR and OL

 But at leaast we are making progress
	

	
	
		
		

		
		
	


	


_

 

Can you check the voltages at the ionput and output or the 7824 voltage regulator. Be careful not to short anything there.


----------



## Ged

I am sorry i do not understand !


----------



## sachu

Can you measure the voltage between both the outer edge pins of the regulator ..the ICP one with the heatsink on it.

 PLace the black probe on SG and the red probe on the each of the outer edges of the regulator and measure the voltage please.


----------



## Ged

the voltages are 24 and 34 volts


----------



## cfcubed

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_The problem now is that even though the LED is turning green there is no switching noise from the relay and no voltage on OR and OL_

 

Never have seen this... IOW whenever LED goes from RED -> GREEN the relay kicks.

 The the modified e12 circuit schem is here.
 Perhaps runeight can chime in, but don't see many ways for CTH to go green but relay not to latch. Especially as you said this CTH worked fine at one point....


----------



## Ged

I wonder if thers another problem I was quite surpised myself but could it be as simple as a faulty relay. the main reason i am surprised is that i heard it latch before

 thanks for the blob of solder trick it works great


----------



## runeight

If the LEDs change then there is voltage being applied to the pads of the relay coil.

 Ged it might be a good idea to measure this. The two power pins are the relay pins towards the front edge of the board. What is the voltage between these two point when the lights are in the two different conditions?

 If there is voltage here then the relay is either bad or has a bad solder joint.

 We're getting closer.


----------



## runeight

Quote:


  Originally Posted by *Billyk* /img/forum/go_quote.gif 
_OK to start I have a more sane supply. 24.4VAC unloaded. It is spec'd at 20v 1amp. Things are cooler for sure I can hold my finger on the reg heatsink now and it's moderately hot just a bit more than warm, so I think things are good there. I changed the tube out, the plate voltages changed from pin1 90v pin 6 81.6v to what I put down below. I also changed the output jack and wiring. I know I changed a lot at once, not the best for troubleshooting
	

	
	
		
		

		
		
	


	




 I cannot recreate the bass distortion and e-12 activation... Hopefully things are better!!
 My measurements as requested.
 Tube:
 1- 78
 2- 0
 3- 1.7
 4- 6.0
 5- 0
 6- 78.4
 7- 0
 8- 1.6
 9- 0

 IC1
 1- 7.5
 2- 11.9
 3- 11.9
 4- 0
 5- 11.9
 6- 11.9
 7- 5.4
 8- 24

 Tube = 6BQ7A_

 


 Billyk these voltage are all well within spec. Are you having any further problems?


----------



## Ged

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_If the LEDs change then there is voltage being applied to the pads of the relay coil.

 Ged it might be a good idea to measure this. The two power pins are the relay pins towards the front edge of the board. What is the voltage between these two point when the lights are in the two different conditions?

 If there is voltage here then the relay is either bad or has a bad solder joint.

 We're getting closer. 
	

	
	
		
		

		
		
	


	


_

 

Cant get a reading when LED red
 When green = 11.5v
 Cleaned and reflowed solder joints no difference


----------



## runeight

OK. This at least makes sense and doing the right thing.

 Need another test.

 Turn off the power and bleed down the 24V PS until it is 0V. If you need to use a 1k resistor across C1P to bleed this all the way down.

 The measure the resistance between the same two pads on the relay where you measured the voltage. It should be about 1100 ohms.


----------



## Ged

The reading for the above is 608ohms


----------



## runeight

I'm sorry. I forgot to ask that you measure with both polarities of the meter. This will test both the diode and the coil.


----------



## Ged

Readings are 1000ohms and 608ohms


----------



## runeight

Well ....

 This would say that the relay coil and diode are ok.

 I guess you're certain that the relay is not closing? With 11.5V on the coil it should be doing something. It has to be doing something.


----------



## Ged

yes i am certain. there was a definite click when it was working


----------



## tacitapproval

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_If any of you experience Q1P failures replace this transistors (BC550C) with one of the BC337-25 transistors as used in the ouput stage._

 

Good news. 

 I have had another Q1P failure just recently. I replaced it with another BC55 and tried to move the regulator away from it some. So far it's good but, if it happens again, I'll know what to do differently.


----------



## runeight

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_yes i am certain. there was a definite click when it was working_

 

Ged, this is going to get a bit hairy now because on the surface, everything seems to be working properly.

 Soooo

 First measure again OG, R18L and R19R with respect to SG. The should be all approximately 12V.

 If they are then replace the diode next to the relay.

 Check the value of R10E to make sure it is 1k.

 Then try to power up again.


----------



## Ged

Did you mean r18r and r9e?
 r18 l ,r18r and OG are all at 12V approx
 r9e is 2kohms ( cant find r10e)


----------



## runeight

Nice typing on my part. 
	

	
	
		
		

		
			





 R18R and R18L. All those voltages are good.

 R10E is next to R13R. Have a look at the silkscreen diagrams on the website to find it. Just want to be sure that it is 1k.


----------



## Ged

found r10e its 1K


----------



## runeight

Thanks.

 I am now a bit stuck. Here's what we know.

 1. OG, R18R, R18L are all at 12V.
 2. The LEDs switch from red to green.
 3. The voltage across the relay coil is 11.5V.
 4. The diode seems to be ok (but we're not certain).
 5. The relay coil resistance is 1k balanced by R10E.
 6. Everything above is exactly right and the relay should trip.
 7. But it doesn't.

 I don't know ...

 Have you actually tried the amp to see if anything is coming out? I'm grasping at straws for the moment. While I think.


----------



## Ged

I cant hook it up as the pot and output inputs are not copleted
 Shall I buy aa relay and diode and go from there
 if there are any other possible parts required please lt me know


----------



## runeight

I guess this is a reasonable step but I am not convinced that the relay is bad. It's pretty hard to burn up a relay coil, particularly in this situation. And the relay measures correctly.

 Although you may want to buy another relay just in case, other possible problems are the diode and/or Q3E. I'm pretty sure that the diode is good too, but may as well swap it out.

 So, if you buy a few more parts include Q3E (MPSA14) on the list.

 Do you have the stamina to remove the relay and test it with a separate 12V supply?


----------



## Ged

have you got any tips to remove the relay
 I have a 12 V /5amp power supply any good?


----------



## cfcubed

Yes, stamina indeed is needed to remove a multi-pin component like a pot or relay from a PCB. I've done it w/a good size "solder blob" moved around the pins w/a small flat blade screwdriver prying edges. But this is not something one has fun doing. Easy to destroy the part & damage the PCB/contacts.

 But this is a stumper for sure. The relay has a "must-latch" of 9V. And you are measuring > 11V at its activation pins. And this relay worked before. I've not had relays go bad except perhaps for decades-old ones.

 My only ideas:

 1) Looking at pg#2 PIN CONFIGURATIONS (bottom view) , we are *sure* *you've got > 11VDC across pins #1 & #12 and its of correct polarity *(+ / -)?

 2) And if so, *we are sure the relay is not latching pins 4->5 & 9->8 when powered *& have checked that w/an ohmmeter?

 If both these are the case then I'd think the relay must be bad. One way to hurt relays is heating their pins for a *very* long time - long enough for the internal wires attached to the pins to come loose. BUT the relay passes the coil ohm test (about 1028R). Although this was in-circuit measurement it appears to counter the loose wire idea.

 Guess would then be relay is somehow stuck in open position... I'd be tempted to give it a short, sharp *wack*





 Edit: If ordering, be sure you've a BC337-25 Q1P replacement around too


----------



## runeight

No. 
	

	
	
		
		

		
		
	


	




 It will just be a matter of sucking the solder out of all the holes, patiently.

 However, do you have a spare MPSA14 (Q3E)? If you do try that first. No likely but better than pulling the relay for no good reason.


----------



## runeight

Or try some of cfcubed's suggests before replacing the transistor.


----------



## Ged

measuring across 4 to 5 and 8 to 9 reveals both are open circuits

 Is this a bad relay

 Thanks guys for putting such a lot of time into this, its really much appreciated


----------



## runeight

It may mean a bad relay but I am still not convinced. The only way to tell, however, is to try to remove it without damaging the board.

 And you are certain that pins 1&12 see 11.5V when the green light is on?


----------



## Ged

Pins 1 and 12 are definetly 11.5V when green light is on


----------



## runeight

Then I guess you'll have to pull the relay and test it out of the circuit. It seems to be the only alternative.


----------



## Ged

for the cost of the relay and the fact that I dont have any thing to test with .I am considering paying some one to replace it as it may have been my soldering that caused the problem bbut the way I see it the voltage is fine at pins 1 and 12soit must be the relay. It may be a simplistic view but I think if the relay is being removed it may as well be replaced


----------



## runeight

OK. Please keep us informed on how you are doing. We need to have another CTH working!!!


----------



## Ged

it will take about a week for parts then i will let you know the outcome


----------



## aphexii

I think this is going to have to be my next build. Is the BOM on the site updated with the latest recommended parts?


----------



## sachu

Quote:


  Originally Posted by *aphexii* /img/forum/go_quote.gif 
_I think this is going to have to be my next build. Is the BOM on the site updated with the latest recommended parts?_

 

Yes, it has been changed.


----------



## aphexii

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Yes, it has been changed._

 

Excellent, thanks! 

 Now to dig through my parts drawers and see what I already have before I place my mouser order


----------



## Billyk

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Billyk these voltage are all well within spec. Are you having any further problems?_

 

Sorry for the delay in answering, no internet!
 Anyway, things are just great! It was the tube. When I swapped it back in the trouble came back. So I have a live and kicking CTH. 
 I really love this little beauty. I am just in awe of the wonderful noise it makes and had a blast building it. Only two issues to troubleshoot, a cold joint on the pot made for a loud buzz and the bad tube that was giving me the distortion issue. 
 Having trouble picking out a favorite tube, have a 12BH7A in there now. The clarity and definition are astounding, even with my poor ol' Senn 515s. Like I said in my sig. gotta stop building this stuff and save for some good cans!!


----------



## runeight

Great to hear that all is working now and that you like the amp!! If you have some time, I'm sure we'd like to hear your further listening impressions.


----------



## tahngarth

I have a BOM question. Both digikey and mouser are out at least part of the BC337/25 or BC327/25 sets. Are the BC32725TACT-ND and BC33725TACT-ND at digikey suitable? I see no difference spec wise and suspect it's a packaging difference. Surprised that they are half the price of the other ones. Also is 604-1061-ND ok for C1L,C1R? Only difference I see is voltage stuff. Sorry for the stupid questions, just not positive of compatibility. Thanks!


----------



## runeight

My quick look says you're ok on both counts. The cap will fit and the transistors seem to be the 25 class.


----------



## sachu

Huzza!! Yet another CTH lives.. This one was a courtesy build for Kabeer who is going to power the legendary Yamaha YH-1000 with it.

 The CTH with the power up problems has been fixed as well..


----------



## wiatrob

YOU should know that it's IMPOSSIBLE for an amp like the CTH to power any amp with a model ending in 1000 (YH-1000, K-1000)!


----------



## sachu

bah...its an improvement over the mini3 for sure..also he didn't want an EHHA cause of space concerns...besides, the CTH does quite well with the Yamaha orthos.


----------



## wiatrob

I think my yh-3s haven't gotten enough time with it - have to try it out this week.


----------



## blaken

What would be a good starting point for R18 for my intended setup

 Source - Zune
 Cans DT770 250

 Here is the twist, I am going to put in a modified Linkwitz crossfeed. I will probably just order Tangents kit unless there is something better close to the price (under ~$50). On his site he recommends a gain 2 to 3x more than normal.


----------



## runeight

I'm not sure what is best, but here's a way to calculate a few things that might help.

 The gain of the CTH is almost identical to the mu of the triode. For 12au7 and similar this is about 17. For 6922 this is about 33. The rest of the tubes, I think, fall in between.

 The output resistors are in series with the load so they reduce the gain by the ratio of R18 to Rheadphones using this formula:

 Actual gain = mu * Rheadphone / (R18 + Rheadphone)

 So, if you are using a 12au7 with 300R headphones:

 R18 = 150R then Actual gain = 11.3
 R18 = 100R then Actual gain = 12.75
 R18 = 50R then Actual gain = 14.6

 For 12au7 with 32R headphones:

 R18 = 150R then Actual gain = 3
 R18 = 100R then Actual gain = 4
 R18 = 50R then Actual gain = 6.6

 Highest gain is, obviously, with R18 = 0.

 Does this help?


----------



## smeggy

I finally got around to stuffing a Tung Sol 6F8G in mine last night... sounds fantastic, lots of air and space. Really nice. Sadly the E12 is still tripping more than I'd like. Other than that, very good, and very big with adapter too. 

 Pics later


----------



## Billyk

Quote:


  Originally Posted by *blaken* /img/forum/go_quote.gif 
_What would be a good starting point for R18 for my intended setup

 Source - Zune
 Cans DT770 250

 Here is the twist, I am going to put in a modified Linkwitz crossfeed. I will probably just order Tangents kit unless there is something better close to the price (under ~$50). On his site he recommends a gain 2 to 3x more than normal._

 

I built a stock CTH with the kit from Spruce Canyon. When I use it with my CD/DAC combo I use the Tangent crossfeed kit. My cans are Senn HD-515, there is no lack of volume with 12au7, 12bh7a, 6fq7, or 6dj8. 
 Hope that helps.


----------



## dBel84

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_I finally got around to stuffing a Tung Sol 6F8G in mine last night... sounds fantastic, lots of air and space. Really nice. Sadly the E12 is still tripping more than I'd like. Other than that, very good, and very big with adapter too. 

 Pics later



_

 

is it later yet? ..dB


----------



## blaken

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_
 Does this help?_

 

Absolutely. That will give me a good idea of where I need to go to maintain the default gain by the BOM resistors. 

 @Billyk Thanks. I assume since you use the kit you like it? 

 I will use sips in those sockets so I can roll them just in case but it sounds like the stock resistors will do fine.


----------



## Billyk

Absolutely! 
 This is an astounding little amp for very short money. Bill put together a nice kit with everything you need and is really great to deal with. He offers magnificent support too.
 I am listening to it with my laptop and a Bantam DAC as I type this. On the PC I use foobar and all the plugins like ASIO4all and crossfeed. When I use a CD player I use my crossfeed box I made from the Tangent PCB and recommended BOM. Plenty of power for my cans and a great sound with plenty of detail and sound staging. I listen to mostly live music and most of that is Grateful Dead 
	

	
	
		
		

		
		
	


	




. I can't wait to get some truly decent cans, I just can't stop building stuff!


----------



## blaken

Doh I don't think I made myself clear. I just meant do you like the crossfeed kit.

 I do plan on buying the amp kit from Bill. He has been helping with a few questions already. In fact I think the only thing left to do is pay him and then I'll be in business 
	

	
	
		
		

		
		
	


	




 I have been interested in the crossfeed because of the closed nature of the DT770s. I like them a lot but they are really in your head and for stuff like live music, Jazz, and Folk rock I would like the sound stage to be more natural.

 Thanks


----------



## Billyk

Yes, I have become addicted to crossfeed and almost cannot listen without it. Like I said when I use the PC and my rockboxed DAPs I use software but on the CD player I use the Tangent PCB and I do like it. At first I did not quite get the effect, but now I really notice it's absence. I use it on the middle position.


----------



## smeggy

yay, pic!






 I really need to recase this thing. 
 Next up, replacing the coupling caps with a pair of Vitamin Q


----------



## blaken

Smeggy you might be taking the term test board a little too literally. That looks insanely awesome.

 On another note where did you get that knob?


----------



## smeggy

Quote:


  Originally Posted by *blaken* /img/forum/go_quote.gif 
_Smeggy you might be taking the term test board a little too literally. That looks insanely awesome.

 On another note where did you get that knob?_

 

Cheers

_*these *_are the ones, I got a pack of four


----------



## blaken

Thanks that guy has a lot of knobs for sale.

 OT: you might be interested in picking up this shirt before they stop making it.


----------



## wiatrob

Madness Smeggy! And how does it sound?


----------



## cfcubed

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_yay, pic!

http://img525.imageshack.us/img525/9240/cthtube.jpg

 I really need to recase this thing. 
 Next up, replacing the coupling caps with a pair of Vitamin Q 
	

	
	
		
		

		
			



_

 

Argh... Imageshack is not serving your cthtube.jpg pic ATM.

 WRT e12 trips, we've given a list of suggestions as tall as your new tube... Could you let us know what you've tried (confirmed parts, measured offset, "desensitized"/slowed it down)? 

 I was getting trips w/toasted Q1P but once they started the CTH was unusable & LV went < 23.5V until I replaced it.


----------



## smeggy

Bah, stupid imageshack!

 Yes, I did the mods to the E12 to desensitize it. What I've been finding is that it seems to be sensitive to how it's placed in the socket. If it's unhappy it'll trip constantly the instant it disengages. Adjust the tube seating and it'll be happy all day.

 I may need to airwire it to ensure it's happy in how the tubes are sitting. I can't see any problems with the socket or the pins. I guess why it was so hard to pin down as it didn't seem tube specific or anything else.

 Sounds real nice too. 
	

	
	
		
		

		
		
	


	




 new pic after adding Vit Q caps






 It's growing.....


----------



## holland

smeggy, where'd you get the adapter?


----------



## smeggy

ebay, they sell adapters for everything. 6sn7, 6f8g, 7n7 etc.

 hmm, seems I've upset the wee thing. Now when I turn it on one LED is bright and the other is on at half brightness but the e12 isn't switching on. Any clues as to what might be amiss?


----------



## Forte

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_ Any clues as to what might be amiss?_

 

It died of shock!
	

	
	
		
		

		
		
	


	




 If it was working before the the Vit Qs went in and now isn't it may be related to those, IIRC a few proto builds had problems when caps with long leads were used but I thought the E12 mods solved that. You could put back the Wimas and see if the problem is still there.


----------



## smeggy

it was working fine with the vit's, something else happened and i can't find what


----------



## MrSlim

Gentlemen.. We need to have an intervention before Smeggy slips completely over to the Dark Side.. It may even be too late now.


----------



## smeggy

I are doomed!


----------



## smeggy

it looks like my rail splitter transistors.. Q3S - Q6S are blown.

 Hopefully Frys stocks them, what exactly is 'the "25" HFE class device' and are they likely to stock them? 

 Common type?


----------



## sachu

Smeggy..wil send some transistors over to you in the package that is heading over to you (SFI pucks and cables)


----------



## bada bing

Just checking in on this thread to report the birth of another CTH. Mine has been up and running now for a little over a week so I'm safely over the hump (knock on wood). Not much of problem with the build, but it sure is a tightly packed board and it's a complicated sucker for such a compact thing. 

 I used the standard kit with the longer hammond case. I swapped out the alps pot for a ebay chinese 10k stepped attenuator, swapped the headphone jack for a neutrik 1/4" and put a "color change" led under the tube. The color changing led gives a cheesy lava lamp-esque look as it rolls through it's colors. I kind of like it.

 I'm very pleased with the sound. I've rolled about a half dozen tubes so far. A Seimens E88cc is the standout so far. A ECC82 tungsram is also pretty interesting. The USA made NOS tubes I've tried so far are pretty meh.

 Based on my surprise at the quality of sound from the CTH, I've ordered 4 boards worth of EHHA. I have a cased dual S22 PSU with umbilical for my B22, I'll borrow it for the EHHA project. Hopefully it'll be interesting. 
	

	
	
		
		

		
		
	


	




 Anyway, thanks Runeight & cfcubed for the CTH project and wiatrob for supporting it with kits. I think I'll take my CTH to work next rotation which should make it the first CTH north of the arctic circle. Here's a couple obligatory pics from my ancient camera.


----------



## Billyk

Most Excellent!
 Welcome to the CTH club. Beautiful looking build.


----------



## cfcubed

Quote:


  Originally Posted by *bada bing* /img/forum/go_quote.gif 
_Just checking in on this thread to report the birth of another CTH. < snip >

 I'm very pleased with the sound. I've rolled about a half dozen tubes so far. A Seimens E88cc is the standout so far. A ECC82 tungsram is also pretty interesting. The USA made NOS tubes I've tried so far are pretty meh.

 Based on my surprise at the quality of sound from the CTH, I've ordered 4 boards worth of EHHA. I have a cased dual S22 PSU with umbilical for my B22, I'll borrow it for the EHHA project. Hopefully it'll be interesting. 
	

	
	
		
		

		
		
	


	




 Anyway, thanks Runeight & cfcubed for the CTH project and wiatrob for supporting it with kits. I think I'll take my CTH to work next rotation which should make it the first CTH north of the arctic circle._

 

Good looking build. Glad you're liking it. You're building up quite a nice collection of amps there
	

	
	
		
		

		
		
	


	




 BTW, Tube-wise I'm happiest using Amperex PQ 6922 (white label/Made in USA) w/my DT880s... At the moment anyway


----------



## keyid

listening to mine atm with with 53' Hytron 5814 its lush, euphoric but not sloppy with an expansive atmosphere. A very interesting signature that mates well with vocals and jazz.


----------



## MrSlim

Does anyone happen to have an extra BC337, for the new Q1P that they could spare?
 I placed a parts order back in the middle of August for my 2nd CTH and just discovered the change on Alex's site. 
 Thanks..


----------



## wiatrob

Um, I might have a few... Let me know what you need...


----------



## MrSlim

Bill, 
 I only need one for now.. unless I blow a few things up.. Trying to be extra careful this time.
 You should have my address from a previous order (I ordered a board and the short perf top). PM me with your costs and I'll get it off to you.
 Thanks!


----------



## sachu

i have a bunch to spare..PM me and I'll send it off to you tomorrow..Bill's busy with something that he needs to send to me first


----------



## wiatrob

Fair enough Sachu - you'll be getting yours soon. Let me know if I can replace the 337's you send to Mr Slim. I have a kajillion or so...


----------



## sachu

I am having a weird problem with a CTH build.

 The relay keeps tripping on and off and then stays off for extended period of time and then randomly starts switching back and forth again before settling to the Off position..

 All voltages except for OL-> SG and OR ->SG check out.

 I tried swapping the opamps out on the buffer and the E12 just to rule them out even though i was getting the proper voltage readings on the E12 opamp (Pins 1, 2 and 6 were at 12 volts)

 The problem I think could be with a possibly faulty relay or the coil voltage not being right.

 Relay pins 1-> SG and 12-> SG read close to 24 volts..this has to be wrong as the coil nominal voltage is supposed ot be 12 volts at least for the relay to be actuated.. Right?
 Pins 3,4,9 and 10 all read 12 volts with respect to SG.


 Here is the relay part

 Appreciate any input.


----------



## smeggy

here's my input, yours is doing exactly what mine is doing. Aside from those suspected blown trannies, this is exactly why we went through the E12 bypass surgery on mine. Sounds like exactly the same thing. So if you do figure it out, I would love to know.


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_The relay keeps tripping on and off and then stays off for extended period of time and then randomly starts switching back and forth again before settling to the Off position..
 <snip>
 The problem I think could be with a possibly faulty relay or the coil voltage not being right._

 

First thing to check is to see if what is happening is that your e12 is doing its job.... IOW, are its trips due to DC offset?

 AFAIR think CTH e12 trips when offset gets like 50mv->100mv on a channel. I'd setup 2 DMMs on the L&R channel *input* to the relay & see what's happening there.

 If its not offset thats causes e12 relay drops and you suspect the relay itself or its voltage drive levels see a few pages back where runeight & I tried diagnosing that in a build...


----------



## runeight

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I am having a weird problem with a CTH build.

 The relay keeps tripping on and off and then stays off for extended period of time and then randomly starts switching back and forth again before settling to the Off position..

 All voltages except for OL-> SG and OR ->SG check out.

 I tried swapping the opamps out on the buffer and the E12 just to rule them out even though i was getting the proper voltage readings on the E12 opamp (Pins 1, 2 and 6 were at 12 volts)

 The problem I think could be with a possibly faulty relay or the coil voltage not being right.

 Relay pins 1-> SG and 12-> SG read close to 24 volts..this has to be wrong as the coil nominal voltage is supposed ot be 12 volts at least for the relay to be actuated.. Right?
 Pins 3,4,9 and 10 all read 12 volts with respect to SG.


 Here is the relay part

 Appreciate any input._

 

The voltages you're measuring are correct for a relay that is not turned on. 3/4 & 9/10 are the NC terminals, connected when the relay is off. 4 and 9 are the outputs from the buffers. They should be at 12V to SG as you measured. 1 and 12 are at 24V making the relay off.

 However, if you are measuring when the relay should be on then there is definitely a problem in the e12 circuitry.

 We desenstized the e12 to trip at about 180mV and we made it slower than the stock version.

 So, if you measure R18R and R18L with respect to OG and these voltages are less than 180mV then the relay should be on. These are the same as pins 4 and 9 on the relay.

 If you can make these last two measurements then we will know something about what condition the e12 is in.

 EDIT: I swapped 9 & 10 in the discussion. I fixed that.


----------



## sachu

Alex, I tried measuring the DC offset.

 It was less than 5mV between pins 4 -> OG and pin 9 -> OG.

 I replaced the relay and tried..no god.

 I replaced D1E and D2E and still no good.

 Verified all resistors and transistors to be in their place.

 Where do we go from here?


----------



## runeight

It would seem that the only devices left are the transistors.

 You might start with the MPSA14.


----------



## sachu

Still the same..I suppose that menas I replace the other 4 transistors and see what happens.


----------



## sachu

bah weak sauce...replaced all the transistors in the E12 and still the same while the offset is well below the threshold.


----------



## runeight

There are not many things left to go wrong.

 Check the orientation of D3E. Maybe it's backwards.

 If not, then measure all pins of the opamp. Make sure it is in with the right orientation. Let us know these voltages.

 If these are all ok remove one lead of R6E to disconnect the lights.

 Still not working? Then remove the relay and check the coil resistance between 1 & 12.


----------



## sachu

D3E is okay.

 removing one lead of R6E made no difference..the relay kept switching back and forth till it settled down to Off position.

 Opamp is in correct position. 

 PIns and voltages
 1-> 0.203V
 2-> 12.03V
 3-> 12.03V
 4-> 0V
 5-> 0.203V
 6-> varies between 11.95-12.17V constantly varying even when relay is in off position.
 7-> 24.06V
 8-> 0V

 Let me know if I need to remove the relay and measure the coil resistance..I did replace the relay with a new one when i did the last series of tests.


----------



## sachu

I have no idea what happened..but while I was trying to measure the output pin 6 of the opamp on turn on to see its behavious I accidently shorted the Vcc pin 7 to pin6 with the probe tip.
 Voila!..it seems to work just fine now. I have 12.01 volts between OL->SG and OR-> SG

 Weird i tell you. Going to wire up and the amp and see if it all works fine.

 Edit:

 I hooked up the wires and set up the amp..it works great. THough with the shunt mod of 33.2k ohm resistors and a 50k ALps pot the amp E12 mutes the output very quickly not to mention not enough travel available on the Volume knob. I will revert to a more standard pot wiring to see if it alleviates the problem. Thanks for the help Alex. It just baffles me what was wrong though. That spark seemed to fix the E12 problem like that . Haha


----------



## rds

I've read a lot here that Grados need a low impedance amplifier, but I find my rs1i sound great from this amp (with r18 = 110 ohms).
 I wonder if Grados really do need low impedance?


----------



## runeight

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Edit:

 I hooked up the wires and set up the amp..it works great. THough with the shunt mod of 33.2k ohm resistors and a 50k ALps pot the amp E12 mutes the output very quickly not to mention not enough travel available on the Volume knob. I will revert to a more standard pot wiring to see if it alleviates the problem. Thanks for the help Alex. It just baffles me what was wrong though. That spark seemed to fix the E12 problem like that . Haha_

 

I am wondering if the opamp was not seated properly and if one of the pins was not actually making contact until you sparked through the oxidation. Other than that your guess is as good as mine. 
	

	
	
		
		

		
			





 rds, the output impedance of the amp is not as important for headphones as it is for speakers. Headphones are mostly a resistive load and so the damping is not terribly important. The "voicecoil" of the headphones does not generate much, if any, back emf into the amp. At least so far as I know. Since it doesn't the series resistors matter only for the gain of the amp.

 OTOH, maybe it's just a great amp.


----------



## acmemr

I finished building my cth two weeks ago and its sounds fantastic, but i have two questions:

 1.) When i switch of the cth, i hear a click in my Headphones. It seems that the protection ciruit ist switching not fast enough.
 Is it normal?

 In operation, Output DC-Offset is below 15mV. After replacing the TL082 with an LT1057, Offset is below 2mV.

 2.) Can i change Q1P to an ZTX451 (80V, 1A, NPN, TO92)


 Thank you in advance.

 CM


----------



## cfcubed

The brief, sharp click you hear @ pwr-off is considered normal for the CTH. It is the tiny delay between the pwr-off & the relay release. 

 You are hearing a fraction of a second of the start of offset caused during pwr-off & only hear it because its getting abruptly interrupted. In other designs that should have the feature but don't, you don't notice their DC offset swings as much because they proceed uninterrupted (to the detriment of your headphones). 

 Don't know about your Q1P sub suggestion (runeight could comment) but BC337 should be sufficient. Interesting observation WRT TL082 --> LT1057.

 BTW another behavior, depending on source & tube, is that CTH's e12 circuit will kick & then re-enable @ connected source's pwr-up.


----------



## acmemr

I noticed, that e12 will kick on very loud and heavy basses.Is it possible that the DC-Servo swings at low Freq. wich will trigger the e12?


----------



## cfcubed

Don't _think_ anyone is experiencing that (if so, chime in). 
 Are you using any parts other than those in the latest BoM (Parts List -> Full Excel BoM)?


----------



## acmemr

I am using only BOM-Parts and it happens only once so far. I play a bassheavy Title from Feuerhake (TickTack) it´s a Trance Track, and Volumepot was at 1pm Position. I´m using a E88CC (6922) Tube. On all other Titles everything is ok. Source was a cheap USB-DAC.


----------



## speedbasslenny

mhhhh -cth-kit arrived today (thanks bill!), but when powering on, q1p starts to become really hot, smoke. any suggestions? (need additional infos?)

 greets, dennis.


----------



## sachu

dennis,

 Remove the regulator LM7824 chip, replace Q1P and then power up. 

 Check voltage at pin 1 or input of the voltage regulator IC. See if Q1P smokes out again. 

 If it does then you have a problem in your power supply section preceding Q1P, else you might have some fried transistors in the buffer and/or splitter circuit.


----------



## runeight

Wow. Many possibilities. THere is probably a short on the 24V side of the regulator which is drawing too much current and then burning up Q1P.

 I know that the CTH is a tight board, but check all of the transistor polarities and make sure they are in the right places. Check the opamps to make sure they are in the right sockets and oriented correctly.

 Check for solder bridges on the board anywhere.

 Let us know what you find.


----------



## runeight

Quote:


  Originally Posted by *acmemr* /img/forum/go_quote.gif 
_I noticed, that e12 will kick on very loud and heavy basses.Is it possible that the DC-Servo swings at low Freq. wich will trigger the e12?_

 

This is possible. The servo is definitely very subsonic though and shouldn't do this at any bass frequency that you can hear. Nevertheless, we have seen that some builds exhibit very unexpected e12 trips.

 You can slow down the e12 or make it less sensitive if you want to do that with a few resistor changes.


----------



## speedbasslenny

ok - q1p replaced and lm7824 removed, voltage between pin 3 and pin 1 is 33,4V, no smoke 
	

	
	
		
		

		
		
	


	




 btw: do r18l and r18r have to be present?


----------



## sachu

yes..R18L and R18R are your output resistors. 

 No smoke means your Power supply section is alright. 

 I would suggest removing all your splitter transistors (Q1S-Q6S) except for the TLE2426 splitter chip.

 Then install a new LM7824 (use the old one if you don't have another). Power it on and check for voltage at pin 3 of the splitter opamp/ IC1S.


----------



## speedbasslenny

enough soldering for today...i'll try it tomorrow. thanks for your help!


----------



## speedbasslenny

mhhhh - found the error, q4p was 550 instead of 560 - after powering on, still smoke. do you have any additions to "change q1s-q6s and remeasure"? 
	

	
	
		
		

		
			





 greets

 dennis


----------



## sachu

umm..lets recap..
 Q4P is an MPSA42 transistor for the B+ stage.

 Can you check and tell me what you had mixed up?

 And you'd want to remove Q1S-Q6S and then take some measurements before replacing them.


----------



## speedbasslenny

my fault, q4r, not q4p!


----------



## sachu

okay..
 well best thing that I can suggest to you is replace all the buffer transistors Q4R-Q7R.
 While I am there I would replace all the splitter transistors just to play it safe.

 I would wait for Alex to chip in first.


----------



## sachu

the steps I would take are:

 remove all splitter transistors Q1S-Q6S. Turn it on, measure opamp IC1S pin 3 and make sure it is reading 12 volts which means the splitter IC TLE2426 is working right. Turn it off, then I would remove and replace with new Q4R-Q7R transistors, plug in the new splitter transistors Q1S-Q6S and then give it a try again.


----------



## cfcubed

Think this thread is a better place for a query Erik made in the CTH tube & tweak thread, a result of CTH's good reception @ the last NY meet.

  Quote:


  Originally Posted by *erikzen* /img/forum/go_quote.gif 
_There is a small group of us in the New York area that wants to start having regular DIY mini-meets, primarily SiBurning. We had one meet in the spring with SiBurning, Kerry and one of SiBurnings friends from outside of Head-Fi. I have very little DIY experience myself but I'm trying to learn. I was thinking the CTH could be a good group project for us._

 

There are a lot of factors that should be considered when one is picking a project, such as going full kit or sourcing parts, build complexity, support, performance expectations, cost, tube vs solid-state, portability, etc. This is why there are so many projects to choose from (PPA, M3, SOHA II, MilletMax, etc.)

 Based on one's experiences, preferences and biases, everyone has his/her own opinions on things. Here is mine in this case:

I consider CTH an intermediate level build (some thoughts here). Lots of parts in a tight space. This makes for a more difficult build than some & one perhaps a bit harder to debug if there is a problem. That said, it is true that if the builder puts the right parts in the right places with the correct orientation the amp should come alive on first power up.. And across dozens (50?) CTH builds, the few that have had problems have been successfully debuged here (AFAIR).
There is a lot of support for the project here and on its official site.
You & the group have heard (or can hear) the amp, so they know exactly what they are working for
	

	
	
		
		

		
		
	


	




 You'd know its a keeper & not one that would end up gathering dust on a shelf (just built to learn from) or in the FS forum.
There are no adjustments pots to fool with.
Full cost comes in around $200USD (full kit, adapter, good tube).
To give yourself some room to work in some upgrades (pots, jacks) & make for easier wiring, I'd suggest Bill's longer-than-std case & perf top offering if choosing this project. 

 As usually the case, it comes down to cost/benefit, risk/reward, trial/error they are what make life interesting
	

	
	
		
		

		
		
	


	




 Other CTH builders can chime in if they wish, of course.


----------



## Billyk

I use my CTH everyday. I really like it, I think if you build it you will too. Won't sit and gather dust as was said.
 I purchased Bill's kit. It was great and everything was there. I would also recommend the longer case.
 It is a great build, intermediate level, you have to be thorough and careful. If you put it together right it will come right up and sound great. If you don't you'll have the backing of a great community to help you get it going.


----------



## speedbasslenny

hmmm - sry for the long time without reply, "work sucks".

 so, after removing q1s-q6s, pin 3 of ic1s is "dead"; no voltage. any suggestions?


----------



## sachu

Quote:


  Originally Posted by *speedbasslenny* /img/forum/go_quote.gif 
_hmmm - sry for the long time without reply, "work sucks".

 so, after removing q1s-q6s, pin 3 of ic1s is "dead"; no voltage. any suggestions?_

 

Hmm, 

 Are you sure you have the regulator LM7824 in place? 
 Are you reading 24 volts on the pin 3 of the regulator?

 If yes to both the above questions, what voltage are you reading at pin 1 of IC1S


----------



## speedbasslenny

mhhh - is it normal when q1s-q6s and lm7824 are removed, theres no voltage at pin1?


----------



## sachu

Quote:


  Originally Posted by *speedbasslenny* /img/forum/go_quote.gif 
_mhhh - is it normal when q1s-q6s and lm7824 are removed, theres no voltage at pin1?_

 

yes..there is no voltage crossing to the splitter if the regulator is removed.

 power down, wait for a while (else there will be sparks when you try to put the regulator back in its place and we don't want that to happen and fry something else.)

 SO put only the LM7824 regulator (Q1S-Q6S are all removed ) back in place, power on and measure pin 1 and pin 3 of IC1S.

 Report back.

 Cheers,
 Sachu


----------



## speedbasslenny

not pin1 at the ic1s, pin1 of the lm7824-slot!


----------



## sachu

Quote:


  Originally Posted by *speedbasslenny* /img/forum/go_quote.gif 
_not pin1 at the ic1s, pin1 of the lm7824-slot!_

 

Hmm..no that isn't normal..you should be reading about 35-36 volts on pin1 of the regulator.
 Very carefully, can you measure voltages at D1P and D3P. Be careful not to short them both when measuring.


----------



## speedbasslenny

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Hmm..no that isn't normal..you should be reading about 35-36 volts on pin1 of the regulator.
 Very carefully, can you measure voltages at D1P and D3P. Be careful not to short them both when measuring._

 

hmm - measure between pin3 of the lm7824slot and d1p?


----------



## sachu

Quote:


  Originally Posted by *speedbasslenny* /img/forum/go_quote.gif 
_hmm - measure between pin3 of the lm7824slot and d1p? 
	

	
	
		
		

		
		
	


	


_

 

No..always measure with respect to SG (star ground).Since you have tombstoned the two diodes, D1p and D3p (they are right next to each other i believe), very carefully with the red probe on the exposed lead on top of the diode and the other black probe on SG..measure the voltages at these two diodes.


----------



## speedbasslenny

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_No..always measure with respect to SG (star ground).Since you have tombstoned the two diodes, D1p and D3p (they are right next to each other i believe), very carefully with the red probe on the exposed lead on top of the diode and the other black probe on SG..measure the voltages at these two diodes._

 


 ahhh, ok 
	

	
	
		
		

		
			





 34,5v! (both)


----------



## sachu

ok..if both D1P and D3P are measuring that and you are not getting similar voltage at pin 1 of LM7824 regulator (chekc to make sure u are measuring pin1) then your Q1P and Q2P transistors need to be swapped out.

 If that isthe case, swap those transistors out and then remeasure at pin 1 of regulator.


----------



## speedbasslenny

ok, i'll swap them ... is there a electronics-friendly way to discharge the caps faster than waiting?


----------



## smeggy

Quote:


  Originally Posted by *speedbasslenny* /img/forum/go_quote.gif 
_ok, i'll swap them ... is there a electronics-friendly way to discharge the caps faster than waiting?_

 

lick your finger and bridge the contacts


----------



## MrSlim

Naughty Naughty Smeggy..


----------



## stringgz301

Well my CTH is up and running. Being a newbie it took me about 2 days off and on working on it to get it put together. Started with the Spruce Canyon kit with upgraded caps. Started on the first try (made sure to check, re-check, and then check one more time all parts) and sounds great. First impression is that my D10 with topkit is now relegated to DAC duty (he's not happy but that's tough). Incredibly three dimensional sound. Currently have a 6DJ8 Bugle Boy in it and enjoying the powerful bass.

 Question: I have a CBS 7730 to try but want to make sure that this will use 6V heater setting. Is this correct?

 Also, what have you guys experienced with burn-in times, especially with the upgraded Sonicaps?

 Looking forward to many hours of listening.


----------



## runeight

Great!!!! It's a nice little amp in a very small package. 
	

	
	
		
		

		
		
	


	




 I think that 7730 is a 12au7 equivalent which means 12V heater setting. Perhaps someone else can verify.


----------



## stringgz301

So I've got a little hum issue. When the amp is on with no music playing I hear a bit of hum. If I crank up the volume the hum gets louder. When I touch the pot or the 6/12v heater switch the hum drops a bit. Also, it sounds like it's coming from the left side (about 11 o'clock on the soundstage). I've got SG grounded to the case and the pot grounded to the same point. I'm wondering if I should have shielded the coupling cap leads. I'm using upgraded Sonicaps here tombstoned and I'm thinking that these long leads (around 1 inch) are picking up some interference?

 Thoughts?

 Edit: it happens with all tubes (both 6 and 12V). I used teflon covered silver wire throughout. Should I have used shielded?


----------



## CYoung234

I have been reading both this thread and the EHHA thread here. I know a number of posters here have built both amps. I realize this is sort of a David versus Goliath comparison, but I am trying to decide which amp to build to power my AKG K-501's and Fostex T50RP (not modded - yet!). I realize I could build the CTH first and do an EHHA down the road.

 There seems to be about a 3X cost difference between the 2 amps, once you add even a modest case into the EHHA cost. I guess my question is - is the cost difference worth it in terms of sound quality? The CTH has the portability going for it, which would be nice, but I can live with the EHHA size, IF the SQ is so much better that it makes it worth the cost difference. I can use it with my main stereo rig pretty easily.

 I listen to mostly classical (symphony orchestra, concertos, etc.), pop / rock (John Mayer, Sheryl Crow, older Genesis, Split Enz, Lucia Micarelli, Sting), some Jazz (Weather Report, Wynton Marsallis, etc.).

 So, can anyone comment on their perceptions of the real sound difference? Is the EHHA really 3X better? Thanks in advance. Oh, you can PM me if you would rather keep this thread less busy.


----------



## TimJo

Quote:


  Originally Posted by *stringgz301* /img/forum/go_quote.gif 
_Well my CTH is up and running.

 Question: I have a CBS 7730 to try but want to make sure that this will use 6V heater setting. Is this correct?
_

 

 Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_I think that 7730 is a 12au7 equivalent which means 12V heater setting. Perhaps someone else can verify._

 

Congrats stringgz301. Your going to love this amp. 
	

	
	
		
		

		
		
	


	




 Yes, the 7730 is an instrument grade 12AU7. Some versions were made with gold pins, some not. Enjoy.


----------



## bmwpowere36m3

Quote:


  Originally Posted by *CYoung234* /img/forum/go_quote.gif 
_I have been reading both this thread and the EHHA thread here. I know a number of posters here have built both amps. I realize this is sort of a David versus Goliath comparison, but I am trying to decide which amp to build to power my AKG K-501's and Fostex T50RP (not modded - yet!). I realize I could build the CTH first and do an EHHA down the road.

 There seems to be about a 3X cost difference between the 2 amps, once you add even a modest case into the EHHA cost. I guess my question is - is the cost difference worth it in terms of sound quality? The CTH has the portability going for it, which would be nice, but I can live with the EHHA size, IF the SQ is so much better that it makes it worth the cost difference. I can use it with my main stereo rig pretty easily.

 I listen to mostly classical (symphony orchestra, concertos, etc.), pop / rock (John Mayer, Sheryl Crow, older Genesis, Split Enz, Lucia Micarelli, Sting), some Jazz (Weather Report, Wynton Marsallis, etc.).

 So, can anyone comment on their perceptions of the real sound difference? Is the EHHA really 3X better? Thanks in advance. Oh, you can PM me if you would rather keep this thread less busy._

 

I would say in general ($/SQ ≠ 1) spending twice as much on an amp doesn't mean you'll get twice the SQ... especially once you build any decent amplifier like you find mentioned on the forum (even a CMoY). I would say that even with the cheapest, simplest amp design your 80%+ there in terms of SQ.

 Many times amps also just "sound" different and match better with different headphones, so it's more of a personal preference. The only major differences I've heard going from a CMoY to a SOHAII is that the latter has better bass control (bass is tight and not boomy) and there's better separation in instruments and highs have more clarity. I would say start small and simple and build from there... once you've heard it and a few other amps you'll know the sound your after.


----------



## runeight

Quote:


  Originally Posted by *stringgz301* /img/forum/go_quote.gif 
_So I've got a little hum issue. When the amp is on with no music playing I hear a bit of hum. If I crank up the volume the hum gets louder. When I touch the pot or the 6/12v heater switch the hum drops a bit. Also, it sounds like it's coming from the left side (about 11 o'clock on the soundstage). I've got SG grounded to the case and the pot grounded to the same point. I'm wondering if I should have shielded the coupling cap leads. I'm using upgraded Sonicaps here tombstoned and I'm thinking that these long leads (around 1 inch) are picking up some interference?

 Thoughts?

 Edit: it happens with all tubes (both 6 and 12V). I used teflon covered silver wire throughout. Should I have used shielded?_

 

Does the hum level change if you move the amp to different loctions? Or closer and farther from line cords, wallwarts, etc?? If yes, then it could be the cap leads. If not, it's probably something else.

 If the amp is inside the hammond enclosure you shoudn't need to use shielded wire on the inside.

 If the hum is not coming from outside the amp then we have to debug the internals and the grounds and the solder joints, etc.


----------



## cfcubed

@ CYoung234 - Others may come in & give you some thoughts on the amps you've asked about. But I did want to sort of echo bmwpowere36m3's comments... Think cost of equipment vs perceived SQ is a diminishing returns thing, like a non-linear curve where you pick your spot. And perhaps move up it, esp if you go to meets & hear other things.

 If you like to build & have the ability, you'll be building more than one amp & the FS forums are very active here, so no decision needs to be final


----------



## CYoung234

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_@ CYoung234 - Others may come in & give you some thoughts on the amps you've asked about. But I did want to sort of echo bmwpowere36m3's comments... Think cost of equipment vs perceived SQ is a diminishing returns thing, like a non-linear curve where you pick your spot. And perhaps move up it, esp if you go to meets & hear other things.

 If you like to build & have the ability, you'll be building more than one amp & the FS forums are very active here, so no decision needs to be final
	

	
	
		
		

		
		
	


	


_

 

Thank you for your reply and to bmwpower36m3 as well (nice car by the way - I drive an e39 5 series myself). Your answers mirror what I suspected I would hear.

 I suspect I will start with the CTH and go from there. I am actually not building this - my twin brother (Pars on this forum), will be. He was the one who originally suggested an EHHA. I have listened to his Gilmore and a few other headphone amps as I have been buying headphones. However, I am a big fan of hybrid amps. My home stereo uses a Counterpoint SA-220 hybrid power amp with an Audible Illusions Modulus 2D preamp, driving Apogee Centaurus ribbon hybrids.


----------



## stringgz301

Tried moving the amp and it has no effect. Hum is slightly stronger when I touch the pot but not much. With no input (jack not plugged in) there is no hum. 

 Setup is Macbook -> D10 (via optical) -> CTH (via line out). When I run directly from the Macbook to CTH via the headphone out there is no hum!!! If I touch the D10 the hum drops about 25%. If I turn off the D10 the hum gets very strong. What is going on?


----------



## runeight

Well, either the D10 is introducing hum or it is causing a ground problem by introducing ground noise into the CTH. Does the D10 float?


----------



## smeggy

my little baby is finally running again and here with me 
	

	
	
		
		

		
			





 Sadly, for whatever reason, there is a huge amount of hum when using the 6f8g tube now. No idea why but it's generating a lot of hum that none of the other tubes do. Touchy buggers!


----------



## stringgz301

Ok, so demonstrating my newbiness, what do you mean by float?


----------



## runeight

Is the D10 grounded in any way separately from the other pieces of equipment?


----------



## stringgz301

Not that I'm aware of. The D10 is only connected to the CTH via mini-to-mini and the macbook via optical.

 Could it be the input jack? I used the one from the Spruce Canyon kit and didn't do anything special to insulate it from the case.


----------



## runeight

It's possible that the input jack is causing problems. I don't think so, but possible. 

 The input jack should be insulated from the case and grounded through its connections to the volume pot which is in turn grounded to the board.

 You could try just disconnecting the input jack from the box just to see what happens.

 Other than that I have to defer to others who listen from a computer. Perhaps they can help diagnose the problem.


----------



## stringgz301

Tried pulling the input jack away from the case. No change. Also tried the CTH with my iPhone as source via LOD and zero hum. Although I still get the whole soundstage "leaning left" so that the center is around 11 o'clock. I'm guessing these are 2 different problems. Somehow the right channel is a little weak?

*EDIT:* More tests.

 1 - CTH volume @ 100%, connected to D10. Some hum
 2 - CTH volume @ 100%, connected to D10, touching CTH volume pot, less hum than (1)
 3 - CTH volume @ 100%, cable removed from D10 (so no source), hum stronger than (1)


----------



## stringgz301

Don't know if this helps in the debugging process, but if I use the same setup (Macbbok -> D10 -> amp -> headphones) but substitute a cmoybb for the CTH there is no hum, unless I touch the cmoybb in which case it is there.

 Could it be the cable?


----------



## runeight

Could be, but my guess is no.

 You have the SG connected to the case? I think you said that earlier.

 Is anyone else out there reading this who has experience running a CTH from a computer?


----------



## wiatrob

Quote:


  Originally Posted by *stringgz301* /img/forum/go_quote.gif 
_Tried pulling the input jack away from the case. No change. Also tried the CTH with my iPhone as source via LOD and zero hum. Although I still get the whole soundstage "leaning left" so that the center is around 11 o'clock. I'm guessing these are 2 different problems. Somehow the right channel is a little weak?

*EDIT:* More tests.

 1 - CTH volume @ 100%, connected to D10. Some hum
 2 - CTH volume @ 100%, connected to D10, touching CTH volume pot, less hum than (1)
 3 - CTH volume @ 100%, cable removed from D10 (so no source), hum stronger than (1)_

 

It shouldn't be the jacks - both are insulated. If there's a change when you touch the pot, I'd suggest grounding the pot. Unless you have and I've missed it as I haven't been following the thread closely. Sorry.

 The soundstage could be the tube as well. Did I sen you an extra tube? Does the behavior remain the same with both?


----------



## stringgz301

Ok. Not sure where the smiley is for "blushing" and "really embarrassed", but I solved the issue. When I wired up the input and output jacks I swapped L and G (R was correct) on both. Somehow, despite this, the CTH still produced music, albeit with some hum. After looking at the wiring diagram for the 1000th time and then looking up the specs for the jacks I discovered my error.

 My CTH is now making sweet music and is ready to be cased up again. Thanks to Runeight and Wiatrob for your patient support.


----------



## runeight

Happy listening. Please let us know how you like it.


----------



## wiatrob

Indeed. Sorry for being a @ss and making you post here - but your travails will help all future builders.

 As we say: 
	

	
	
		
		

		
		
	


	




 BTW, it's:


----------



## cfcubed

I'm pleased to report all the qualities that make CTH a very nice headamp make it a very nice preamp as well
	

	
	
		
		

		
		
	


	








 That's a std CTH feeding my FW F1 clone powering Hornshoppe horns. I've had my share of SS & tube preamps & this puppy competes well. 
 BTW, CTH having offset protection & muting delay make this possible, with the F1 being a DC amp, I'd not try this unless it did. Used a mellow Mullard to complement F1/HSH serious presentation, so CTH's tube rolling is a must as well.

 Use std 100R R18s & a better-than-std pot if building a CTH for headamp/preamp duty. I _know_ we'll be seeing such a CTH around these parts in the next month or two


----------



## cfcubed

Got a nice, *small* package from wiatrob yesterday.

 I was reminded how compact this feature-packed baby really is
	

	
	
		
		

		
		
	


	







 Had Bill omit some parts for me as I'll be using a few that are bigger (pot, case, etc.) than std for this next build.





 Putting kits like this together is certainly not trivial & must really be a labor of love... Thanks again Bill!


----------



## suicidal_orange

I'm looking for a project and this looks like a good option. The board looks very cramped but I like a challenge, and my CK²III build was perfect first time so why not! Just got a couple of questions before I ask about shipping costs which hopefully someone can answer 
	

	
	
		
		

		
			





 First as this amp has a tube in it it should not be turned on/off too often? This is closely related to the second - how hot does it run? The vented case looks a bit scary to have on all the time in the summer... no air con in the uk 
	

	
	
		
		

		
		
	


	




 Last (and possibly most important!) most of my listening is through K340's which are notoriously hard to drive - how will the CTH cope?

 Thanks for any thoughts


----------



## runeight

suicidal_orange, welcome to the cth. 
	

	
	
		
		

		
		
	


	




 I think that wiatrob has some kits available at spruce canyon labs if you want to go that route. Boards are available from Cavalli Audio (me).

 It's ok to turn the amp on and off as much as you like. Tubes are designed for this and, although it is better to leave the heaters on continuously, there are other drawbacks to this. In addition, unlike other compact tube hybrids, this amp will take a very large variety of 6.3 and 12.6 volt tubes, many of them in current production. So you won't have any problems finding tubes for it.

 If you get the kit and case from spruce canyon, there will be sufficient ventilation even in the heat of summer.

 I can't answer #3, but perhaps another owner of the amp can.


----------



## Forte

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_I'm looking for a project and this looks like a good option._

 

Go for it, its a fantastic little amp.

 Its not a difficult build as long as you are careful, read through the build instructions a few times before you start to familiarize yourself with the build and double check each component before you solder it in. Pay particular attention to the tombstoned diodes and transistors and you should not have any problems.

 While the amp does run hot it is well within the limits of the components and the amp is not big enough to act as a room heater! There is a slight improvement in SQ to my ears after the amp has had an hour or so to warm up so on a weekend it stays on, during the week I just turn it on when I get a chance for a listen. 

 Can't help on the K340 question either, but it does fine with all the headphones I have tried including a pair of Yamaha HP-1 orthos which also have a reputation as hard to drive. I can tell you it will be a great match for your Woodied Grados though.

 Since receiving my Grado HF-2s this has become my favourite combo by far.


----------



## Stereo_Sanchez

Very impressive thread. Thanks to all of their input.


----------



## wiatrob

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_suicidal_orange, welcome to the cth. 
	

	
	
		
		

		
		
	


	




 I think that wiatrob has some kits available at spruce canyon labs if you want to go that route. Boards are available from Cavalli Audio (me)._

 

Indeed, there are kits available. I am no longer supplying bare PCBS, these will be available from Runeight...


----------



## Forte

Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Boards are available from Cavalli Audio (me)._

 

How does anyone order these and will you be supplying boards direct for any of your other designs?


----------



## cfcubed

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_Go for it, its a fantastic little amp.
 Its not a difficult build as long as you are careful, read through the build instructions a few times before you start to familiarize yourself with the build and double check each component before you solder it in. Pay particular attention to the tombstoned diodes and transistors and you should not have any problems.
 While the amp does run hot it is well within the limits of the components and the amp is not big enough to act as a room heater! There is a slight improvement in SQ to my ears after the amp has had an hour or so to warm up so on a weekend it stays on, during the week I just turn it on when I get a chance for a listen. 
 < snip>
 Since receiving my Grado HF-2s this has become my favourite combo by far.
	

	
	
		
		

		
		
	


	


_

 

I'd like to echo Forte's thoughts here w/a few embellishments of my own:
Dead on WRT building. Review CTH site info well & print scaled-up copies of images & left few cols of excel BoM. For me a tedious but useful step was sorting the kit resistors & taping them to their rows in the enlarged BoM. Watch polarized cap orientation too (long lead is +). I'll post a couple more closeups of a populated PCB when its ready. Once you get past the resistors think its smooth sailing
	

	
	
		
		

		
		
	


	


WRT heat, you have to have a couple Nelson Pass amp designs around to know what heat is
	

	
	
		
		

		
		
	


	




 As said, and across many builds, we've no heat-related issues (esp. since Q1P re-spec a while back). Mount comps low & w/a bit of wiggle room near 24V reg & you'll be fine.
OT: Forte - Seeing another post of yours it seems you & I will end up w/B22 & HF-2s as well. From the NY meet, opinion was it would take critical listening in a quiet environment w/A/Bing to pick out any compromise WRT my budget B22 build. Guess that's a testament to the B22 design. And HF-2 mated very well w/CTH & B22. So far, after 1 day w/HF-2s, I'm finding the better mastered material is rendered very accurately w/relentlessly revealing B22 (great), so of course poorer mixes/mastering shows through as well (not as great). CTH w/good tube choice seems to somewhat mask the objectionable aspects of less-then-ideal recordings as one would expect (from an amp w/a tube in it). So its nice to have both types of designs in one's arsenal


----------



## suicidal_orange

Thanks for all the opinions, I'll not be discouraged that the build isn't hard as it will probably be attempted during the Christmas break so a stress free build will be good 
	

	
	
		
		

		
		
	


	




 I was worried about it being a room heater if it needed that much ventilation, it doesn't ever get really hot enough in the UK to think it would damage itself just that I like things cool (I'm still wearing a t-shirt out and some days it's not reaching 50°F - some call me mad 
	

	
	
		
		

		
		
	


	




) but summer cannot be used as an excuse to stop listening. I'll just turn it off lots and have an excuse to buy spare tubes just waiting for them to die 
	

	
	
		
		

		
		
	


	




 Now to sort out the ordering - wiatrob will have an e-mail shortly!


----------



## Forte

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_I was worried about it being a room heater if it needed that much ventilation, it doesn't ever get really hot enough in the UK to think it would damage itself just that I like things cool (I'm still wearing a t-shirt out and some days it's not reaching 50°F - some call me mad 
	

	
	
		
		

		
		
	


	




) but summer cannot be used as an excuse to stop listening. I'll just turn it off lots and have an excuse to buy spare tubes just waiting for them to die 
	

	
	
		
		

		
		
	


	




 Now to sort out the ordering - wiatrob will have an e-mail shortly!_

 

Don't worry about the temps, it's the first week of summer here and the temp hit 100°F yesterday and its going to get a lot hotter before long. My build has the solid top with just a few small vent holes and copes just fine with being left on.

 If you haven't already ordered consider the Sonicap upgrade, well worth the cost.


----------



## suicidal_orange

I've just read a reply to my semi order, no stock of Sonicaps but I've been offered some Russian paper in oils which wiatrob says are 90% of the Sonicaps so I'll probably go with them. It's a nice cheap upgrade, I'm not one to turn that down. Or should I try and source them elsewhere? Which caps are they anyway? I'm not good at understanding schematics to work out the values


----------



## runeight

They are C4L and C4R. These are the primary audio coupling caps between the tube stage and the transistor buffer. Of all the places in the amp where cap upgrades are possible this is the only one that really makes sense and will have an audio impact. 
	

	
	
		
		

		
		
	


	




 Please let us know how you do.


----------



## cfcubed

See the CTH Tube & Tweak thread for discussion of those (de)coupling caps. As the only capacitors in the primary signal path they do have an influence on the sound, tho less so than the choice of tube. In fact, the "voicing" of the amp is accomplished though a combo of tube/coupling cap choice with the tube the much larger part of the equation.

 You can spend 60 cents -> 60 dollars or more on the 0.22uf coupling cap & more $$ may not mean more to your liking. From what I've read those green Russian PIOs may give a slightly more mellow presentation than the std or WIMA caps & I'll be finding out for myself w/this next build. I think I'll go w/Bill's green PIOs because the CTH does not lack detail & they might make it a bit more "tubey" for fun.

Some more reading for you. Don't stress on this tho
	

	
	
		
		

		
		
	


	




_Edit: I guess I'm too wordy as someone else beat me to it. Again._


----------



## suicidal_orange

I've read a lot about signal path capacitors from playing with iMods, and more money = better (all the way to V-Caps...) but I've not tried many in the middle. At 0.22uf it seems size may be the limiting factor instead of budget, but I'm only on page two of the tweaks thread so will keep reading before making a decision.

 Thanks again for the help 
	

	
	
		
		

		
		
	


	




*EDIT* - Just read in the tweaks thread that the CTH handles a K1000 so my K340's should be fine


----------



## wiatrob

I DO have Obliagto Gold .22s, and (Yikes!) Russian Teflons already leaded for the CTH. No way you can fit them in the case - same with the more esoteric film caps because of their higher voltage.

 As implied above - spend your money on Tubes, I have stock Wimas in my proto that I've never felt the need to change.


----------



## Billyk

I'm with Bill on this. Save your $$$ for tubes. A nice Bugle Boy or something like that will be money well spent. ( not to dissuade you, but...)


----------



## adamus

amen, the wima's are very good value for money. Obbligato's are very nice too. 

 Spend on the following - amperex BB, or amperex 8416 pq.


----------



## keyid

x2 

 Go with wimas for reference and upgrade later. 
 Amperex BB or 8416 will sound great. 

 For Senns I recommend Tesla ECC802S


----------



## wiatrob

x3 on the 8416. Getting tough to find...

 Enjoying Tungsram ECC82 right now...


----------



## sachu

An RCA cleartop 6CG7..the only tube you'll need for the CTH.


----------



## suicidal_orange

I've just placed an order for a kit, including the Russian PIO's as they will actually fit in the case. I read that this amp is small, but hadn't actually measured it out - it's tiny! No wonder it can't heat a room. Has anyone used it as a portable with a battery?

 I'llave to wait for Christmas before starting my build, so plenty of time to look for tubes. Are there any good places to look in the UK apart from ebay? All the recommendations are £15+ (~$25) but in the tweaks thread people were using $10 ones. Considering they are made in Europe this seems somehow backwards


----------



## cfcubed

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_ I read that this amp is small, but hadn't actually measured it out - it's tiny! No wonder it can't heat a room. _

 

Yes it is. 
 It has more features than many full-sized desktop headamps in a space less than a 3" X 5" index card. And uses no SMD. It's quite an achievement & you get to feel that sense of achievement once you complete it
	

	
	
		
		

		
		
	


	




 Think there is a scale PDF somewhere on the official site you could print.
  Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_Has anyone used it as a portable with a battery?_

 

Nope.


----------



## keyid

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_x3 on the 8416. Getting tough to find...

 Enjoying Tungsram ECC82 right now..._

 

yea they are getting hard to find, I managed to borrow one but was noisy on the CTH 
	

	
	
		
		

		
		
	


	




  Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_An RCA cleartop 6CG7..the only tube you'll need for the CTH._

 

love this tube with hf2, the raytheon 6cg7 black plates is also very nice.


----------



## Billyk

It is with much happiness that I happened upon a pair of Bugle Boys in a box in my basement while I was searching for something. What a nice find, they sound very nice indeed!


----------



## helzerr

Just wanted to chime in with my success story: My first CTH build passed all the initial tests with flying colors!

 I'm waiting on audio jacks which were back-ordered at Mouser so I can case it up and have a listen.

 Initial impressions are:

 1. The build process was smooth and trouble free with the exception of making room for the updated C3H. The C4L & C4R Wima upgrade caps are also a tight fit.

 2. The (12BH7A) tube doesn't light as brightly as anticipated. I have verified 12.6 V DC across pins 4 & 5.

 3. The CTH doesn't generate as much heat as I'd been lead to believe from reading the forum.

 Thanks to everyone who made this project possible, I can't wait to listen!


----------



## Billyk

Glad you like it, It's my current favorite, I use it every night. I am using the BB I mentioned above. I will say regarding the heat that some of the tubes will generate a good bit of heat. The 6DJ's run the amp very cool and sound great, the 6cgs sounded good but ran it very hot. The heater currents sure have an impact.


----------



## wiatrob

Just to let everyone know, Spruce Canyon Labs CTH kits are sold out, and will not likely be restocked in the future. As previously stated, Cavalli Audio will now supply PC boards.

 The web site will be updated soon to reflect this. Seems I can't get in to make updates. ooops.

 I may offer a GB on the last of the custom end panels, depending on how many are left.

 Thanks to everyone who bought a kit!


----------



## dpmiller

Thank you, wiatrob, and runeight, for this nice amp. I really like it, and the kit was a great option for me at the time.


----------



## BoxOPwn

Can PCB's still be purchased from Spruce Canyon Labs?


----------



## Billyk

Thank you, Bill, for making this awesome amp so easily available. You made it easy for me to own such a treasure. Thanks to Alex for such a neat design.
 I love mine and use it everyday!

 Edit: I wopuld be interested in the end panels!!


----------



## keyid

whats next bill? stacker II kits! I hear theres a new prototype


----------



## sachu

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_ stacker II kits! I hear theres a new prototype_

 

Wouldn't that be nice... 
	

	
	
		
		

		
			





 Doubt we'll see these. Wishing it goes commercial.


----------



## wiatrob

Quote:


  Originally Posted by *BoxOPwn* /img/forum/go_quote.gif 
_Can PCB's still be purchased from Spruce Canyon Labs?_

 

No. Contact runeight directly.


----------



## wiatrob

Quote:


  Originally Posted by *keyid* /img/forum/go_quote.gif 
_whats next bill? stacker II kits! I hear theres a new prototype_

 

Nope. Heads down away from the hobby for a bit. Except maybe a small project or two.


----------



## devast

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Just to let everyone know, Spruce Canyon Labs CTH kits are sold out, and will not likely be restocked in the future. As previously stated, Cavalli Audio will now supply PC boards._

 

Looks like i took one of the last kits from Bill 
	

	
	
		
		

		
		
	


	




 Thanks again!


----------



## cfcubed

For now I suppose that prospective CTHers can get PCBs from runeight & full BoM spread is up there. Maybe Bill or someone can share actual Mouser & Digikey BoMs to assist.

 Yep, owe Bill a debt of gratitude. Putting together 150-old piece kits takes dedication


----------



## wiatrob

I'd be happy to share mt latest Mouser/DigiKey BoM, has subs for obsolete parts, etc. As soon as I get a chance I'll post it and send a copy to Runeight.


----------



## si foz

Ive just recieved confirmation that I have got the last kit via Bill. Looking forward to recieving it.
	

	
	
		
		

		
		
	


	




 1st post too!


----------



## HeadphoneAddict

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_I'd be happy to share mt latest Mouser/DigiKey BoM, has subs for obsolete parts, etc. As soon as I get a chance I'll post it and send a copy to Runeight._

 

I probably will regret not getting one of these while I had the chance, don't you think? But I have to remind myself, just when would I get to listen to it with all the other amps crammed into my house?


----------



## sachu

Hey guys,

 Been working on a couple of CTH boards here and both seem to be having the same problem, which is, the E12 is tripping ON and OFF every few seconds. I haven't tried BOM coupling caps yet as I think I am out of those at the moment. 

 All voltages are checking out fine, the inputs to the ICE are both rock steady at 11.7/8 volts but the output of the opamp is varying continuously.

 Any help is appreciated. Edit: I have tried swapping opamps and that didn't help it any.

 I hate the damn E12.


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_I hate the damn E12. 
	

	
	
		
		

		
		
	


	


_

 


Think you'd hate an amp that needs e12 & doesn't have one & blows your cans much more. Sure the muting delay & pwr-off cut-off are most important, but it might also be catching build errors.
As Alex says, CTH e12 is derived from original, so we should say "CTH's e12" when complaining about it.
Having finished another one, once I brought my CTHs up to *current* BoM spec have not had any CTH e12 problems.
You have the most experience debugging these things
	

	
	
		
		

		
		
	


	


 Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Been working on a couple of CTH boards here and both seem to be having the same problem, which is, the E12 is tripping ON and OFF every few seconds. I haven't tried BOM coupling caps yet as I think I am out of those at the moment._

 

Did this build ever work properly? Assume you've tried a couple tubes...
 Did you use new parts from the new BoM, install cleanly & wash the flux off?
 Do the relay input leads show offset sufficient to trip CTH's e12? 
 IOW, ia this a case of the circuit doing its job & detecting build problems (or actually something w/CTH's e12)?

 BTW I had a theory about why some had CTH e12 probs wwaayyy back w/old BoMs & w/large coupling caps on long leads. Maybe they were installed incorrectly. The outer foil is supposed be input (tube side) & inner foil the output. If one installed them w/outer foil on output I'd expect the cap to pick up more EMI & perhaps cause more noise & offset flux.


----------



## sachu

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_
Think you'd hate an amp that needs e12 & doesn't have one & blows your cans much more. Sure the muting delay & pwr-off cut-off are most important, but it might also be catching build errors.
Aye..though my big amps don't use this and the only thing I am afraid of is a power outage while listening to either of them 
	

	
	
		
		

		
		
	


	




As Alex says, CTH e12 is derived from original, so we should say "CTH's e12" when complaining about it.
Indeed..but the original circuit is quite the pesky little thorn in the backside too 
	

	
	
		
		

		
		
	


	




Having finished another one, once I brought my CTHs up to *current* BoM spec have not had any CTH e12 problems.
This is the first of which I have had too since the latest spec..and two in a row!!

You have the most experience debugging these things
	

	
	
		
		

		
		
	


	



Heh, so some people say 
	

	
	
		
		

		
		
	


	





 Did this build ever work properly? Assume you've tried a couple tubes...
 Did you use new parts from the new BoM, install cleanly & wash the flux off?
 Do the relay input leads show offset sufficient to trip CTH's e12? 
 IOW, ia this a case of the circuit doing its job & detecting build problems (or actually something w/CTH's e12)?

They are new builds actually..just had the parts lying around for ever now and so decided to finish them up. I will check on the voltages on the relay tomorrow (just got finished fixing the non working board on my EHHA..am tired now, but relieved. 
	

	
	
		
		

		
		
	


	




. Yes the flux has been cleaned off with rubbing alcohol, caught a few mistakes when i did my pre power up checkups (really should stop soldering late at night)

 BTW I had a theory about why some had CTH e12 probs wwaayyy back w/old BoMs & w/large coupling caps on long leads. Maybe they were installed incorrectly. The outer foil is supposed be input (tube side) & inner foil the output. If one installed them w/outer foil on output I'd expect the cap to pick up more EMI & perhaps cause more noise & offset flux.

Hmmm, what exactly do you mean by inner and outer foil? The way i have it now is that the caps are tombstoned and the leads are exposed on the buffer side. I gather that is probably troublesome?_

 

My replies in italics.


----------



## cfcubed

> They are new builds actually..just had the parts lying around for ever now and so decided to finish them up.

 I mean new parts as in unused parts & by new BoM I mean the current one from 8/27/09 (the latest BoM rev. I believe).
 Yes, not an amp to work on while tired, in a rush or toasted
	

	
	
		
		

		
		
	


	




 > what exactly do you mean by inner and outer foil? 

 It may not be a biggie but it would make sense to me that the outer foil could pick up wide-range EMI spikes (e.g. relay click) & if connected to output could pass them. Whereas using the outer foil as input (connected to tube) might block some of this along w/the DC it blocks. Just me guessing tho.
*My bet is that w/new (8/2009) BoM parts this doesn't matter & a properly built CTH is rock solid regardless.*

 Search "inner foil" here, here and here for a start.

 Good luck & watching the DC offset @ input to relay should narrow the prob.


----------



## sachu

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_I mean new parts as in unused parts & by new BoM I mean the current one from 8/27/09 (the latest BoM rev. I believe)._

 

yep..all new parts and based on the indicated BOM spec.

 I will take some measurements today and see where i get.


----------



## acvtre

What would you say about the CTH plus senn hd600, does anybody own this rig?
 I'm going to buy 'em, since they are more neutral than the hd650.


----------



## MrSlim

I've got a pair of HD580s that I use with a CTH at home and they sound very nice. Not quite the same as 600's but I've heard rumors that they are very close(same drivers), and there has to be a reason Sennheiser obsoleted the 580s (too close to the 600s?). 
 I've got a 650 cable and 600 Grills on mine, not sure how much diff it made, the cable is much more robust, and I like the look of the 600 grills(although they are not as cheap any more).


----------



## sachu

Okay..been monitoring the voltages on the relay input and they seem quite steady at 11.8 volts. They do, both channels vary around from 11.8 to 11.85 volts but that can't be the reason why the E12 is tripping.

 Now of course if i remove the opamp in the E12 altogether the relay trips and i see the correct voltages on the output of the relays and it stays that way. Once i introduce the opamp back into the circuit the E12 starts hoping about madly.

 I removed the coupling caps and put them in with the outer foil towards the input and the inner foil towards the output(buffer side). No change.
 Reflowed the joints on all points which i felt might be iffy, but no change. Checked to make sure the transistors are all in their places and everything seems fine.

 With the opamp in the circuit the output of the opamp in the E12 varies madly by a coupleof volts naturally triggering the E12..but what is causing this variation is something i haven't been able to work out yet.

 Any theories?


----------



## cfcubed

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Okay..been monitoring the voltages on the relay input and they seem quite steady at 11.8 volts. They do, both channels vary around from 11.8 to 11.85 volts but that can't be the reason why the E12 is tripping._

 

I'd meant to measure the offset the CTH's e12 is monitoring... E.g. OG/OL & OG/OR into relay (so Vs WRT OG). 
 The numbers you quote sound ok, but would still be nice to know actual mVs of offset the channels have prior to & after relay kick.


----------



## wiatrob

Hey, I can comment on this amp now that I'm not selling it anymore. 

 The CTH is AWESOME with the entire range of Senns. I found it to have great synergy with the 600s (which I was using as my work cans with the CTH for about 8 Mnths).


----------



## Duckman

Hoping not to get flamed for asking a question without having read the thread; but here goes:

 I just purchased Wiatrob's CTH and am considering a pair of Beyer T1's. Any ideas how the CTH performs with 600 ohm headphones?

 Cheers!


----------



## sachu

Quote:


  Originally Posted by *Duckman* /img/forum/go_quote.gif 
_Hoping not to get flamed for asking a question without having read the thread; but here goes:

 I just purchased Wiatrob's CTH and am considering a pair of Beyer T1's. Any ideas how the CTH performs with 600 ohm headphones?

 Cheers!_

 

It will do just fine. The amp is a powerhouse actually, in the time I've had it, it has been able to drive the K1000 and my ID1 (albeit not as well as an EHHA does for the latter, but impressive nonetheless). 

 It is a very versatile amplifier. Find a matching tube to your taste and it'll keep on surprising you.


----------



## wiatrob

Quote:


  Originally Posted by *Duckman* /img/forum/go_quote.gif 
_Hoping not to get flamed for asking a question without having read the thread; but here goes:

 I just purchased Wiatrob's CTH and am considering a pair of Beyer T1's. Any ideas how the CTH performs with 600 ohm headphones?

 Cheers!_

 


 Also, Duckman's 'new' CTH is not working. I suspect the trafo - any CTH owners from Down Under have a 24V transformer suggestion?


----------



## sachu

oooh..seems i may have found a problem with on the CTH board. For R6R and R6L i am using 30k instead of 31k. Now that should affect only the plate voltage right? but I am reading 19.34 V on the cathode (pins 3 and 8) of the tube. That should be reading 2.4V or thereabouts.
 Would using 30K for R6 affect the voltage on the cathode pins of the tube?
 Edit: *facepalm* turns out i made a rookie mistake and put in 30 ohms instead of 30k. replaced R6 and now i have 2.4V on pin3 but pin8 is still reading 1.1V instaed of 2.4V. Pin 2 of that opamp is reading 3.1 volts instead of 2.3/2.4V. No idea why that is..will need to make sure other resistors are as they should be.


----------



## Forte

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Also, Duckman's 'new' CTH is not working. I suspect the trafo - any CTH owners from Down Under have a 24V transformer suggestion?_

 

Best would be Jaycar, they have a 24VAC 1A https://secure4.vivid-design.com.au/...T&SUBCATID=381 , you would need to purchase a connector separately though as it just has bare wires on the lead end.

 Altronics used to sell the same one but now only seem to have a 24VAC 900ma plugpackAltronics - Your One Stop Audio Visual & Electronics Supplier , haven't seen this so don't know if it comes with a connector or what size.

 DSE used to sell this AC Adaptor 24Vac 1.5A (M9635) | Dick Smith Online Store, but appears it to be discontinued, you may get lucky though if you try your local store(There are a few stores in Victoria that still show stock), I managed to pick up one cheap as clearance stock a few months back, came with 1/2 a dozen different interchangeable connectors.


----------



## cfcubed

WRT A/C adapters, I now *always* use a fuse in series until my builds are complete. Learned the "hard way" by blowing the internal fuse in the one on left (and opening these is a battle - added fuse holder to one on left):



 Must have replaced the fuse in that left adapter 4 times now across my protos & builds
	

	
	
		
		

		
			





 Once proofed I use the adapter on right. Do need to pay attention to plug size OD/ID, but while on bench I use a loose jack wired to board matching fused adapter.

 Pretty sure Bill's kits ship w/fuse & holder and they should be used at least up until just before case-up. Use of an ohmmeter on A/C-in to check for shorts is also wise.

 BTW I've gotten all my A/C adapters off fleabay & none have cost > $15 shipped, but might not work that way for Aussies. Look for >= 750ma.


----------



## suicidal_orange

While on the subject of wallwarts is there anything special I should be looking for? Some are switching while others say nothing (is this just unnecessary marketing?) I'm in the UK so need a 230v model, none of those pictured are. 24v AC and >750ma with a 2.5mm pin - is there anything else I need to look out for?

 I got my kit for Christmas and am about half way through the build so will hopefully need power before new year


----------



## acvtre

Quote:


  Originally Posted by *wiatrob* /img/forum/go_quote.gif 
_Hey, I can comment on this amp now that I'm not selling it anymore. 

 The CTH is AWESOME with the entire range of Senns. I found it to have great synergy with the 600s (which I was using as my work cans with the CTH for about 8 Mnths)._

 

How would you describe the sound signature? With what kind of valve have you matched 'em?


----------



## wiatrob

Always, ALWAYS use the fuse! I've had the same issue as CFCubed, shorted wires and the occasional reversed diode. These will save your butt every time...


----------



## wiatrob

Quote:


  Originally Posted by *acvtre* /img/forum/go_quote.gif 
_How would you describe the sound signature? With what kind of valve have you matched 'em?_

 


 Sorry, I have tin ears so you'll have to ask someone else about sound signature. 

 I can only say what I like: 6H30 supertube, Amperex 8416, Raytheon 6GU7 BUT:

 Please check this thread for some great info:

http://www.head-fi.org/forums/f6/cav...thread-417322/


----------



## wiatrob

Update on ε22 trips and coupling capacitor lead lengths:

 I just hooked up some GIANT russian teflons, they are mounted boardside with 3-4" airwired leads.

 While they sound like poop, they do not cause any extraneous trips, even when I move the caps around the board trying to get them to do so...


----------



## cfcubed

Yep, I think we've pretty much eliminated the large cap/long lead bit as a factor in CTH ε22 trips. 
 I've have noticed that wildly differing cap type/size influences time to relay latch... IOW, the time it takes offset to settle down. E.g. I've found big honking caps w/smaller honking caps (sonicap gen I w/gen II bypass) takes almost 2X as long to relay latch than little bitty WIMAs.


----------



## wiatrob

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_While on the subject of wallwarts is there anything special I should be looking for? Some are switching while others say nothing (is this just unnecessary marketing?) I'm in the UK so need a 230v model, none of those pictured are. 24v AC and >750ma with a 2.5mm pin - is there anything else I need to look out for?_

 

Switching won't work, as it would be DC - Don't use 24V*DC* under any circumstances!

 You want to make sure it IS rated for 24VAC GREATER THAN 660 mA. 

 I know higher is psec'd but I've run plenty with 3/5 of an amp. It's pretty straightforward to graft on a 2.5mm connector cable 9I find actually wiring the plugs to be a pain though). Or I could send you a 2.1mm jack if you can find a proper wall wart with that connector...


----------



## sachu

Well we my CTH #11 is up and running. I can't seem to find a 100uF/100V cap to finish up CTH #12..anyone got a spare they can send me, save me from putting in an order?


----------



## funch

I'm placing a Mouser order tomorrow. Get me a part #, and I'll send it
 when my order comes in.


----------



## sachu

Quote:


  Originally Posted by *funch* /img/forum/go_quote.gif 
_I'm placing a Mouser order tomorrow. Get me a part #, and I'll send it
 when my order comes in._

 

Sweet..will send you a PM. Thanks a lot for the offer! 
	

	
	
		
		

		
		
	


	




 Edit: Oh and the completed CTH.


----------



## Duckman

Quote:


  Originally Posted by *Forte* /img/forum/go_quote.gif 
_DSE used to sell this AC Adaptor 24Vac 1.5A (M9635) | Dick Smith Online Store, but appears it to be discontinued, you may get lucky though if you try your local store(There are a few stores in Victoria that still show stock), I managed to pick up one cheap as clearance stock a few months back, came with 1/2 a dozen different interchangeable connectors._

 

I was lucky enough to score one of these transformers, but have a question:

 the ends are indeed interchangeable and can be fitted so that the polarity is either positive or negative. Which polarity should I use?

 (Already PM'd Wiatrob and Forte about this: but am so keen to hear the CTH, I thought I'd post here also)

 Cheers!


----------



## Duckman

Got the answer: thanks Jon!


----------



## wiatrob

Well, never mind my PM, seems you figured it out...


----------



## cfcubed

Quote:


  Originally Posted by *Duckman* /img/forum/go_quote.gif 
_I was lucky enough to score one of these <snip>
 (Already PM'd Wiatrob and Forte about this: but am so keen to hear the CTH, <snip>_

 

As you have your answer now are your hearing it yet
	

	
	
		
		

		
		
	


	




?


----------



## cfcubed

Just in case some are subscribed to this thread, please see my latest post to CTH tweak thread for findings WRT coupling caps, 6F8Gs & CTH/e12 latch sensitivity.


----------



## suicidal_orange

Well I finally got a wallwart (24VAC 1A) and plugged in my CTH. I hear a clicking and turn it off after maybe 5 seconds - the last cap I attached (C10P) was backwards. Swapped it around, turned it in again and let out some smoke 
	

	
	
		
		

		
		
	


	




 I've looked (and smelt) it over but can't see anything thats obviously cooked. All the other caps are correct, and the diodes are the right way round but I can't see to read the numbers. I didn't rush the build so they should be correct, but if I made one mistake maybe there's another 
	

	
	
		
		

		
		
	


	




 The only other thing I noticed was that the first time the LED was green and the second red if that helps...

 Do caps die that quickly? What else would have died if this cap did? The smoke didn't seem to be coming from the cap, but was from that end of the board. I was stood back by the plug incase you were wondering, to be quicker than 5 seconds if needed without risking being covered in blown cap (never seen one blow, but it doesn't sound fun)

 Thanks for any help


----------



## cfcubed

It is a shame & mystery why member sachu is presently banned, because he'd have post diag steps by now. He has the most experience with this. Oh, well, the community suffers.

 C10P is the main cap in the HV section. It is hard to say what has been damaged. I've had smoke rise from components and try as I might can see which ones. Usually smoked resistors are obvious, blown/vented caps really stink & you see residue, but damaged transistors are harder to spot. They usually have to really be burned to show the damage. 

 I'd first carefully review the parts & orientations against the many files on CavalliAudio. Once you are sure all the right parts are in the right spots & correct orientation you can begin trying to crawl through the build (from PS in forward). You should at least check that C10P that was reversed hasn't vented/raised its top. And google for checking caps - using ohmmeter then reversing leads on the cap may tell you something.


----------



## cfcubed

Quote:


  Originally Posted by *acvtre* /img/forum/go_quote.gif 
_What would you say about the CTH plus senn hd600, does anybody own this rig? I'm going to buy 'em, since they are more neutral than the hd650._

 

BTW, now that I've HD650s I can say CTH drives them very well. 
 Only owning HD650s for 16hrs & doing a little tube rolling, 6922 PQ & 8416 is good w/them. But I've a bunch of tubes to try & I think there are better matches.


----------



## mugdecoffee

I've been ordering parts for a CTH but have gotten stuck on the LM2595 regulator. Neither mouser nor digikey has them in stock and I can't find a place to get a sample for one either. Anyone know where to try? I'm also missing a 220uH 0.8A inductor which I would really like to get from the same place to avoid more shipping costs if possible.


----------



## scompton

NATIONAL SEMICONDUCTOR|LM2595T-ADJ/NOPB|DC/DC Converter IC | Newark.com


----------



## suicidal_orange

I located the source of the smoke 
	

	
	
		
		

		
		
	


	




 Q1P now has a nice burn hole in the flat side. When I turned it on to find this out the LED went green after about 20 seconds, and the smoke stopped. Turned it off, replaced Q1P with a fresh one plugged it back in and - nothing. No smoke, and a 0v reading between SG and OG...

 C10P looks to be dead as the top has noticeably raised, so I'll have to order a replacement but I'm worried as to why the whole amp appears to have died. Any ideas? I'll order a new cap today, but don't really want to be wasting money on postage.


----------



## cfcubed

If one looks at the PS schematic, we see that C10P is the last HV cap & Q1P critical in the LV. This might only leave the heater supply "standing" in your amp.

 Before placing a parts order it would be good give us time to assess everything that _might_ need replacement. With any luck your heater supply is intact because those parts are harder to source. Since you've been powering up this damaged amp anyway, can't see harm in seeing if the heater is alive. So power it on & see if the tube heater glows (OR measure V across pins 4 & 5 of tube socket for 6.3 or 12.6).

 I think the only thing that'd take out Q1P is a (near) short down the line from it (it's emitter). So look for incorrect 24V orientation (it's reversed from what you'd think it should be) and/or a (near) short at 24V reg output. For a start.


----------



## suicidal_orange

Thanks cfcubed, I wish I actually understood electronics 
	

	
	
		
		

		
			





 I've just measured pin 4-5 at 12.6v, so thats something, but after another long look with a magnifying glass can't see any shorts. As for 24v orientation would that be the T0220 at ACP? I assumed the metal tab corresponded with the white silkscreening - if that's backwards it probably would be a problem!

 Thanks again


----------



## cfcubed

Good, so it seems one of the 3 PS supplies is OK (the heater).

 We are not sure about the HV section, if lucky replacing C10P might get that working. It'd be nice to know before ordering parts. Is there any way you can grab, say a 100V 100uf from someone/someplace over there? Since we expect only up to 110V in that position, it would be enough for a test. Maybe post a quickie thread request for a 100uf 100v->160v cap?

 Yes, the metal tab of the 7824 LV ICP reg aligns w/the solid white line (it faces "out", whereas the heater reg faces "in"). There are two things that would help:
 1) clear high-res pictures of the top & bottom of board,
 2) resistance (ohm) measurements for each of the 2 end pins of the 7824 LV ICP to ground (its middle pin).


----------



## suicidal_orange

Pictures are a no go, I only have an old phone camera phone and close-ups are not good. If it wont work any other way I'll borrow a camera and let you admire my (lack of) soldering skills. 

 ICP is the right way round and measures 75.5 on the 200k scale on the side towards the end of the board and 8.7 on the side towards the middle of the board. Seems a big difference, but maybe that's normal? Neither are shorted at least.

 I've been looking around at caps and found out that Farnell has free shipping so I ordered one. Only £1 and should be here on Tuesday as Christmas and the snow are both in the past. 

 You mention a 3rd supply - is this dependent on the HV being operational?


----------



## cfcubed

> Neither are shorted at least.
 Yes & your measurements do not seem dramatically off to me (as you say, not shorted).
 I measured one of my boards - 4K to center of board (vs your 8.7K) and 150K to rear of board (vs your 76K). So still a mystery why Q1P shorted for you.

 > You mention a 3rd supply
 They are reasonably independent. Looking at the ps schematic:
*Top - High Voltage*. We expect about 105V @ the last common capacitor, C10P, the one that popped by having been reversely installed. BTW, the long lead is +.
*Middle - Low Voltage*. 24V section, Q1P is the main cap multiplier transistor & in normal operation it does get warm. Should not burn as it did for you.
*Bottom - Tube heater*. 12.6v / 6.3v.

 As tube heater looks OK, after new C10P is installed you'll check for 100V or so between TB+ and ground (SG). Be careful, avoid shorts & shocks. For me 100V zap is enough to get my attention, not much more.

 Then the mystery of your Q1P / LV section.


----------



## suicidal_orange

Well C10P is measuring 108v so that looks healthy (once replaced) and with the heater working fine it's just the LV to sort. I swapped out Q1P again and managed to pull one of the holes out, so have some creative use of leads under the PCB now, didn't help though. 

 What does a blown diode look like? I found a pic of one cracked in half which was obviously dead and none of mine look like that, but D2P looks duller than the others and kind of like it's peeling - could this be the problem part?


----------



## cfcubed

Luckily, I've not seen a blown diode. But they are not hard to remove & easy to test (ohmmeter one way then the next - google it).

 Too bad about trace lifts... It takes a while to develop some proficiency @ removing the little guys. I use a "solder blob" on PCB bottom for multilegged semis... E.g. try to liquefy all 3 solder joins while pulling on part from top. Best if you've a PCB vise for this.
 Then just clean up w/soldering wick, solder vac, etc.

 Since we don't know what popped your Q1P, it might be nice to have it on leads
	

	
	
		
		

		
		
	


	




 As you suspect D1P, I'd *really* check from ICP back to A/C (D1P - D4P) for part #s, orientation, shorts. If the problem is not @ Q1P's emitter (its load) maybe it's got to do w/its base (its bottom/vertical line in PS schem).


----------



## Ged

HELP!
 Ihave just got my cth together and initially it worked. But now the right channel is not working.I have tested all the wiring between input,output left and right and the pcb pads and left/right are idenical . Could you give any suggestions to sort this out


----------



## cfcubed

How long did it play properly?

 My 1st inclination is try swapping the tube, 2nd a cold solder joint.


----------



## Ged

Tried swapping tubes no joy
 I do not understand that using a DMM set to ohms reveals both readings in ohms on both channels to be identical could it still be a cold solder joint.

 Could you please tell me which pins on the tube socket aare the heater pins so that I check the orientation of my heater switch


----------



## Forte

Quote:


  Originally Posted by *Ged* /img/forum/go_quote.gif 
_Could you please tell me which pins on the tube socket are the heater pins so that I check the orientation of my heater switch_

 

Pins 4 & 5


----------



## Ged

thanks forte


----------



## mugdecoffee

Another CTH lives! The build was pretty straight forward and I didn't have any major troubles. I decided to go for Auricaps right off the bat. They were a real pain to install because their leads were about twice as wide as the hole. I ended up cutting half the strands off to get the rest in.

 Since the kits recently ran out, I had to source all the parts. I was surprised how little the basic parts cost. Not that the kits were expensive. My mouser order was around $80 I think includes a couple things for another project. The case, i/o connectors, pot, and Auricaps cost easily more than the bare parts. If anyone else sources the parts themselves, the parts list on the website was often incomplete or had incorrect quantities. The Excel spreadsheet was complete though along with part numbers.

 For now I'm using a 6N1P tube left over from my Bijou which has a decent soundstage but sounds a bit thick. I have some tubes on the way though.


----------



## cfcubed

Quote:


  Originally Posted by *mugdecoffee* /img/forum/go_quote.gif 
_Another CTH lives!_

 

Nice. Will keep an eye out for impressions down the road...

 Anything much bigger than BoM C4 caps, esp any with thick leads, can be a pain. When/if there's a PCB rev that's an area we'd be looking to revise.

 And yes, we've focused on keeping the excel parts list accurate & up-to-date. We were looking to get actual Mouser/Digikey BoMs out there to make it even easier.


----------



## mugdecoffee

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_And yes, we've focused on keeping the excel parts list accurate & up-to-date. We were looking to get actual Mouser/Digikey BoMs out there to make it even easier._

 

I copied the list of mouser part numbers straight into their BOM importer tool and it worked flawlessly. Not sure how you could make the excel BOM more complete. The only real work I had to do was finding alternatives for about 5 out of stock parts. Really a smooth build which reflects on how much forethought you guys put into this. Thanks for putting it all together.


----------



## mugdecoffee

So I finally got my case and installed the CTH in it. First, there's noise now thats not really a hum but a sharper buzz sound. Secondly, I blew a couple fuses before realizing that my case which has not yet been grounded is 12.4ish volts above ground. This is not the output ground voltage which is just under 12 volts. As long as the case isn't grounded, it works fine except for the buzzing. I checked all the obvious points (e.g. power, different signals, grounds) to chassis and they're not shorting. Any ideas? Maybe some part of the heater supply is hitting it causing the buzzing?


----------



## keyid

check wiring on the pot, are the grounds connected?


----------



## mugdecoffee

Turns out the AC input jack was no insulated and it was shorting to the case if the power cable was turned a particular way. I need to order an insulating one. In the meantime, the buzz is gone since there isn't AC flowing around the input RCAs.

 Another build note: I mounted my board to the case using screws with hex nuts and the nuts in several places were too close to components and wouldn't turn. It'd be nice if in the next generation of CTH boards the mounting holes had a little more room around them.


----------



## tahngarth

Well, off and on building over the past few months, and a CTH is alive! I (of course) have a problem. 
 I'm not pretty sure I've been running my tubes at the wrong voltage. I started with a 6gu7, it got hot, filaments turned red, and not knowing any better I used it like that for hours. Moved to a 6n6p, same story. Tried a 12au7, switching to "12" volts and it sorta worked, but one channel was much quieter than the other. Together I probably ran each 6 volt tube for 6-7 hours each over the past couple days.
 Today I tried the 12 volt in "6" volts and it worked! Tried a 6 volt tube at "12" volts and it also worked, but without the glowing filaments. 
 I'm going to take a multimeter to work tomorrow and verify the voltages across pins 4/5, but right now I'm assuming I screwed up. The real question here is how likely is it I did any permanent damage to the amp it's self, especially running the 6n6p at 12 volts. Everything seems to be fine currently for what it's worth.


----------



## tahngarth

.


----------



## cfcubed

The heater switch is "open" for 12.6V & "closed"(0 ohms) for 6.3v.

 Think the amp will cope w/this fine, but not sure about tubes (e.g. tube life, etc.). If you could find a tube tester somewhere you could test 'em, otherwise let your ears be the judge.

 If you look @ CTH Tube & tweak thread you'd see you are not alone mistakenly running 6.3v heated tubes @ 12.6v. Most of these heaters should not glow too brightly & are often hard to spot in normal lighting. And quiet/low gain for a 12.6v tube could indicate its running @ 6.3v.


----------



## tahngarth

Thanks for the input. I had done some searching in this thread, but didn't think to look through the tweak thread. There is definitely some discoloration on both tubes, especially the 6N6P tube. We'll see tomorrow how well they coped. Hopefully this als explains the low hum. Even with running the tubes at the wrong voltage I've loved every second so far with this amp. Time to compile a list and hit up a local electronic's place. A quick look through their mess of tubes revealed a few 12au7's and a 6gu7(which I guess I'll get now) so I'm hopeful to find some more.


----------



## mudo

Hello. First of all please excuse my ignorance with electronics. I'm nearly done ordering the parts to build the amp, but I can't find equivalences for these mouser references:

140-XRL100V100-RC (could 647-UVR2A101MPD1TO work?)
581-BQ014D0222JDD
647-UVP1C101MPD
551-EC2-12NJ

 I'm also going to make orders to digikey and farnell so I don't care if these missing parts come from any of them.

 Hope you can help. Thank you!


----------



## cfcubed

> but I can't find equivalences for these mouser references.

 As you are asking, would have to defer to any others that might have build up CTHs with parts other than those from Mouser.... And of course not those that used wiatrob's kits (btw, he may still have some CTH parts around - not sure & not sure if he'd do int'l on 'em).

 I suppose you've looked for any pin- & value-equivalents that meet or exceed ratings & stay close to size constraints (based on datasheets of the parts you listed). IOW, you _may_ be able to squeeze in slightly larger parts for some of them (print scale PDF & search for populated PCB pics, etc.).


----------



## stringgz301

Has anyone played with larger values for C4? This appears to be the interstage coupling cap and so would have a significant effect, especially on low frequencies. I'm using the CTH with Grado's, a low impedance phone (32 ohm), which in theory would make them more sensitive to the value of this cap. I've been playing around with bypassing C4 and was very surprised with the effect of adding a .022mF bypass to the .22mF recommended cap. The amount of very low end went up significantly, which seems surprising given that I only added 10% overall capacitance.

 Thoughts?


----------



## Forte

Quote:


  Originally Posted by *stringgz301* /img/forum/go_quote.gif 
_Has anyone played with larger values for C4?_

 

I asked about using larger values early on and was told that the roll-off point was so low that larger cap values would have no audible difference, so have only experimented with different cap brands and not values. Have read that cap bypassing can have very mixed results depending on the combo used, some work and some don't. Sounds like you have hit on a combo that work well together.

 What caps are you using and how have you mounted them? Its a tight fit to get one cap in for each C4, let alone two.


----------



## devast

Hello.
 I'm in the middle of building mine, from wiatrobs kit. I've got a question: There's one heatsink included in the kit. Should i use that for 7824 regulator, or the lm2595 ? I could fit that on either of them.
 Thanks!


----------



## Forte

Quote:


  Originally Posted by *devast* /img/forum/go_quote.gif 
_ I've got a question: There's one heatsink included in the kit. Should i use that for 7824 regulator, or the lm2595 ?_

 


 The heatsink is for ICP, the 24V regulator(7824).


----------



## netsky3

There is a kit that is possible buy for build this amp??


----------



## devast

Quote:


  Originally Posted by *netsky3* /img/forum/go_quote.gif 
_There is a kit that is possible buy for build this amp??
	

	
	
		
		

		
		
	


	


_

 

There was. Bill stopped selling it 3-4 months ago. I'm too busy nowdays, so i did not have any free time to build mine, even though i had it for months.
 For the build:
 I switched c5p and c10p so my 1000uf 50V capacitor emitted some smoke and died peacefully 
	

	
	
		
		

		
		
	


	



 I'll get a new cap tuesday, and i hope nothing else died there


----------



## netsky3

Quote:


  Originally Posted by *devast* /img/forum/go_quote.gif 
_There was. Bill stopped selling it 3-4 months ago. I'm too busy nowdays, so i did not have any free time to build mine, even though i had it for months.
 For the build:
 I switched c5p and c10p so my 1000uf 50V capacitor emitted some smoke and died peacefully 
	

	
	
		
		

		
			




 I'll get a new cap tuesday, and i hope nothing else died there 
	

	
	
		
		

		
		
	


	


_

 

ouch!
 And if I would to build an amp like this (or similar) where I can buy a kit under 100€?


----------



## devast

I'm happy to announce that another CTH born today, she's alive and kicking hard. One word can describe her... FANTASTIC! 
	

	
	
		
		

		
		
	


	




 @netsky3
 Bill is not selling CTH kits anymore, and i don't know about similar amp kits.


----------



## MrSlim

Quote:


  Originally Posted by *netsky3* /img/forum/go_quote.gif 
_ouch!
 And if I would to build an amp like this (or similar) where I can buy a kit under 100€? 
	

	
	
		
		

		
		
	


	


_

 

You might be able to do it for under 100 Euro, but I think the shipping costs will put you over, probably closer to 150. 

 There is no kit right now but the BOM for the amp is here:
The Compact Tube Hybrid Amplifier

 along with a very thorough build and testing plan. The unfortunate part is that you have to buy a couple of parts from Digikey, the rest are available from Mouser, so you have to pay the extra shipping cost. 

 Send "runeight" a PM here, he is Cavalli Audio, and his website says that the boards are available from him (although I can't find a Contact address anywhere on his site) 

 I've built a couple of these babies and they are very nice.


----------



## cfcubed

Quote:


  Originally Posted by *devast* /img/forum/go_quote.gif 
_I'm happy to announce that another CTH born today, she's alive and kicking hard. One word can describe her... FANTASTIC!_

 

Nice to hear its up & running... So the little guy survived the cap incident.

 Great too that you enjoy the sound. Now if you can resist buying _too_ many tubes for rolling. I know I couldn't


----------



## sachu

Quote:


  Originally Posted by *devast* /img/forum/go_quote.gif 
_I'm happy to announce that another CTH born today, she's alive and kicking hard. One word can describe her... FANTASTIC! 
	

	
	
		
		

		
		
	


	



 ._

 

Nicely done....i know the feeling of resurrecting a CTH after a component failure during the build. 

 Enjoy her


----------



## smeggy

Bugger, I want another one with all the tweak soup-ups.


----------



## sachu

Quote:


  Originally Posted by *smeggy* /img/forum/go_quote.gif 
_Bugger, I want another one with all the tweak soup-ups._

 

hehe..weird, I feel the same way about a particular set of pants 
	

	
	
		
		

		
		
	


	




 Edit: You've turned to hoarding amps now considering you only had a 'lowly' mini3 about this time last year.


----------



## devast

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Nicely done....i know the feeling of resurrecting a CTH after a component failure during the build. 

 Enjoy her 
	

	
	
		
		

		
		
	


	


_

 

Was doing that. But i think i managed to fry Q1P and Q2P today. I connected the headphone out to my computers line in, pressed the power button, funny smell, and led is not glowing... No biggie, i will resurrect her again 
	

	
	
		
		

		
		
	


	




 edit: later on i realized what i have done. Basically, i shorted SG to OG 
	

	
	
		
		

		
		
	


	




 edit2: Do you think anything else could have died in the rail splitter circuit? I'm not sure about that, it should have taken "lighter" overload.


----------



## stringgz301

I've been playing with caps in C4 and currently have a .33mF cap in place. I'm getting strange behavior:
 - with 6dj8 no problems
 - with 12au7 on cold start e12 keeps tripping
 - with 12au7 on warm start (CTH warmed up with 6dj8 and then tube swapped) no problems

 I'm guessing that this config is very close to the e12 trip threshold. I've searched and found several suggestions to change the e12 resistor values in this case but no details on which values to update. 

 Anyone solved this issue before?

 Thanks in advance.


----------



## sachu

Quote:


  Originally Posted by *devast* /img/forum/go_quote.gif 
_Was doing that. But i think i managed to fry Q1P and Q2P today. I connected the headphone out to my computers line in, pressed the power button, funny smell, and led is not glowing... No biggie, i will resurrect her again 
	

	
	
		
		

		
		
	


	




 edit: later on i realized what i have done. Basically, i shorted SG to OG 
	

	
	
		
		

		
		
	


	




 edit2: Do you think anything else could have died in the rail splitter circuit? I'm not sure about that, it should have taken "lighter" overload._

 

Go about it a step at the time.
 Am guessing the buffer transistors are probably toast. you could try the simple multimeter test on the BJTs for a start but i'd recommend removing the 7824 regulator IC, turn it on and see if Q1P and/or Q2P burn out. If they do, then you have something else wrong in your power supply. 
 If they are are fine, then check to see if you have about 34-35V on pin1 pad of the 7824 regulator.

 , turn the amp off, If that is fine then remove all the splitter transistors, leave the ground splitter IC in,
 plug in the regulator IC and turn the amp on..check to see if you are seeing 12V on pin 3 of IC1S. 
 If that is fine, then go ahead and turn off the amp, plug in the splitter BJTs and see what happens. 
 If you aren't getting 12V on pin 3 of IC1S opamp then replace the splitter TO-92 part and check for voltage level at pin 3 of the opamp again. 
 If you are getting 12V then plug in the splitter ICs and turn on the amp.
 if things are still blowing, you will again have to do the whole thing again and also replace the buffer transistors.


----------



## cfcubed

Quote:


  Originally Posted by *stringgz301* /img/forum/go_quote.gif 
_I've been playing with caps in C4 and currently have a .33mF cap in place. I'm getting strange behavior:<snip>_

 

My *guess* is since you passing more signal (below audible?) using more-than-spec capacitance (> 0.22uF), this introduces the CTH e12 latch sensitivity. IIRC, I had similar symptoms when I tried big, honking Sonicap Gen I 1.0uF caps in the C4 positions.

 Anyway, as far as de-sensitizing CTH's e12 I can only say that I *know* we posted the CTH component #s & recommended values for doing that... Either in this thread OR the Tube & tweak one.


----------



## devast

Quote:


  Originally Posted by *sachu* /img/forum/go_quote.gif 
_Go about it a step at the time.
 Am guessing the buffer transistors are probably toast. you could try the simple multimeter test on the BJTs for a start but i'd recommend removing the 7824 regulator IC, turn it on and see if Q1P and/or Q2P burn out. If they do, then you have something else wrong in your power supply._

 

Q1P and Q2p are 100% toast. I turned it on and measured no voltage at the 24v regs input leg. I'm trying to figure out if anything else has died as well or not, unfortunately i don't have my spare transistors with me 
	

	
	
		
		

		
		
	


	




 I don't think i can do the multimeter test on transistors that are soldered in the circuit already, or i'm getting some weird reading on them (some i tried to measure randomly).


 Edit: Replaced Q1P and Q2P, and it's working again. Thanks for the support tho


----------



## devast

Quote:


  Originally Posted by *devast* /img/forum/go_quote.gif 
_Edit: Replaced Q1P and Q2P, and it's working again. Thanks for the support tho 
	

	
	
		
		

		
		
	


	


_

 

It's not perfect yet. Somehow, my E12 trips at specific points of a track, over a specific volume level. I have found only one track that trips, this never happened before on that track. I've got my VG at +12V(11,94V according to my budget multimeter), and E12 behaves like it did before for example at startup. Maybe i've damaged ICE? I have no clue. High power (white noise and pink noise) tracks play without a trip at high volume.

 edit: I replaced basically the whole rail splitter. E12 still tripping 
	

	
	
		
		

		
		
	


	




 Tried replacing ICE too, still the same. I think something died there maybe... any clues? Also, it's tripping when there's no phone plugged in (lol).


----------



## devast

Quick bump. It's still tripping. Can anyone do the following: do not plug headphones into the cth, set the volume pot to max, and start playing something. It immediately trips for me, and i wonder if it does the same to others. I replaced some stuff in e12 yesterday, and came to a conclusion that e12 is fine 
	

	
	
		
		

		
		
	


	




 Now i'm suspecting the output buffer... Already tried an opa2134 at IC1 position, no change.


----------



## cfcubed

Yes, we should have suggested to see if your CTH's e12 is "doing its job" when its tripping. One way to do this is by measuring DC offset (in mV) from OG to each "input" pin of the relay. Looking at PCB the relay "line input" pins are 2nd ones over from OR/OL side of relay. 

 When I'd a problem I'd solder wires to those relay pins & use 2 meters to watch offset during the trips... To confirm e12 or OB. IIRC, when there was trouble it was more often in OB parts. I took the fastest sure route to repair - replaced all OB transistors + OPA. But some were successful at targeting & replacing specific parts.


----------



## suicidal_orange

After a long time away from this I've finally ordered some desoldering braid and a solder sucker, to start disassembly to work out whats gone wrong with my CTH. 

 Back a couple of pages I'd ordered a new C10P having reversed it, that's now fitted and I read 117v between TB+ and SG (thanks cfcubed 
	

	
	
		
		

		
			





) so that now looks sorted so it's just my LV stage, and it looks like sachu posted debugging steps only a couple of posts ago - I may have a new amp for the weekend


----------



## sachu

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_<snip> that's now fitted and I read 117v between TB+ and SG <snip>_

 

That voltage is 10 volts too high I believe compared to specs..will need to see if the rest of the voltages check out once you have the LV section figured out.

  Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_ I may have a new amp for the weekend 
	

	
	
		
		

		
		
	


	


_

 

Good luck.


----------



## cfcubed

> That voltage is 10 volts too high I believe compared to specs.

 It may be just that his A/C adapter is running a little high, which is fine (e.g. one of mine does 27VAC+ under load). The HV cap specs have plenty of headroom for this.
 Note though that sachu sure knows his way around CTHs so we'll see


----------



## suicidal_orange

Thanks guys, this theme of ~10% too high seems to be continuing - removed the 7824, replaced Q1P and Q2P just to be sure and it now measures 41V to pin 1... same for both SG and OG so seems there is a short somewhere? Back to the magnifying glasss 
	

	
	
		
		

		
		
	


	




 No smoke though?

 Now to show my noobness again, which is the BJT(s) to test? Sounds easy enough once I know


----------



## devast

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_Thanks guys, this theme of ~10% too high seems to be continuing - removed the 7824, replaced Q1P and Q2P just to be sure and it now measures 41V to pin 1... same for both SG and OG so seems there is a short somewhere? Back to the magnifying glasss 
	

	
	
		
		

		
		
	


	




 No smoke though?

 Now to show my noobness again, which is the BJT(s) to test? Sounds easy enough once I know 
	

	
	
		
		

		
		
	


	


_

 

From my understanding of the circuit, the B+ has nothing to do with q1p/q2p or the 24v reg. The circuit on the top of the picture, that is where you need to find the error. Good luck! I need some luck as well with mine


----------



## sachu

DOn't worry about the B+ for now, you will only know if that is OK once you put the tube in. You may just end up running the tube hotter, which is not a bad thing really. Just make sure your LV section is fine. 
 Are you saying you are getting 41V on pin 1 wrt OG and SG?


----------



## suicidal_orange

Thanks devast, I have (had?) two problems with my build. I got excited at the prospect of listening to it and put in the last and biggest cap (C10P) in backwards, so that nearly popped. Replaced it and now C10P is reading 130V. if it wasn't for pin 4-5 still reading 12.7V (only .1V up on last time) I'd have suspected the multimeter...

 Completely unrelated Q1P burnt out (nice melt hole in the side...) but no idea why. I've just had a lunch break and come back to notice that my creative lead work has connected Q1P to Q2P, but not to the circuit... Connected it and no change. 

 I'm not giving up this time, it will work!


----------



## suicidal_orange

Having been on for about 30 minutes pin 1 of the 7824 measures 42V to either OG or SG, if that increase means anything to anyone?

 I still see no shorts


----------



## suicidal_orange

Another unhappy update

 Decided to test the dodgy multimeter idea so put in a new battery. First test? Resistance between 1-2 on ICP. Shorted it, blew half the front off Q1P. Replaced that and decided on the safer voltage check - pin 1 to either SG or OG now reads 5.2v 
	

	
	
		
		

		
		
	


	




 Not sure I'm going to be able to sort this, I'm too careless


----------



## devast

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_Another unhappy update

 Decided to test the dodgy multimeter idea so put in a new battery. First test? Resistance between 1-2 on ICP. Shorted it, blew half the front off Q1P. Replaced that and decided on the safer voltage check - pin 1 to either SG or OG now reads 5.2v 
	

	
	
		
		

		
		
	


	




 Not sure I'm going to be able to sort this, I'm too careless 
	

	
	
		
		

		
		
	


	


_

 

Just my idea, but i think you blew q2p as well. I'd try replacing that as well.


----------



## suicidal_orange

Thanks Devast, you're probably right but it's not really going to help much - it didn't work even with both transistors in even when they didn't explode!

 I've just removed, verified and tested all the caps and diodes in the LV section and they're all fine. Not sure how to test the 7824 but it's not even got hot enough to melt the thermal tape to the heatsink and wasn't in when I shorted it's pads so should be ok. So now to try and think what caused Q1P to burn in the first place. 

 I remember the LED being on before it burnt and never since, so I looked to see where the LED is - is this the "to lights" indicated on the right of the E12 schematic? I'll take the E12 parts out too if that's where the problem is...

 Thanks again


----------



## suicidal_orange

So I've given up on being spoon fed (this is DI*Y* afterall 
	

	
	
		
		

		
		
	


	




) and actually read the test site. Removed and checked the resistors and cap in the rail splitter, all fine. Swapped IC1 with ICL - no change. Replaced all but the 2426 and I still have no joy, but no smoke either! 

 I guess the 2426 is a very sensitive part to be listed specifically in the guide? Guess I'd better buy a replacement...

 I've just re-checked the resistances on the 7824 and now it reads 8.2 to the middle of the board (200k scale) and the outer isn't connected but has 2.66V across it. C10P now reads 116v, pin 4-5 in the tube 12.7V but 1-6 is back to 0V.

 I'm close to just buying new parts for both the dead supplies, but that seems overkill...


----------



## devast

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_I've just re-checked the resistances on the 7824 and now it reads 8.2 to the middle of the board (200k scale) and the outer isn't connected but has 2.66V across it. C10P now reads 116v, pin 4-5 in the tube 12.7V but 1-6 is back to 0V.

 I'm close to just buying new parts for both the dead supplies, but that seems overkill..._

 

So. My ideas (i'm no expert):
 12,7V on tube pin4-5 is ok if your switch is set for it, meaning your heater supply seems ok. Always measure the voltage to the SG. Pin1 of the 7824 to SG should read something like ~34V(30-38) or so, even when you have 7824 removed(I'd try measuring that pad while 7824 is removed). Pin3 should read 24V when 7824 is installed. If you got the first reading ok, then probably your 7824 is dead. I wouldn't worry much about the other tube pins until you can get the 24V functioning.
 your C10P value seems ok as well i think.


----------



## suicidal_orange

Thanks again Devast, expert or not your help and encouragement are much appreciated 
	

	
	
		
		

		
		
	


	




 So I measured pin 3 to SG at just 2.7V. Removed the 7824 and pin 1 to SG reads 35.7V so that's where my problem is. So in your inexpert opinion do I buy a 7824 or 3 of them, expecting it to blow again?

 EDIT: http://uk.farnell.com/taiwan-semicon...0-3/dp/7174071 <-This one looks to be suitable?


----------



## sachu

having a couple extra of the 7824s is handy.


----------



## jezz

I'm confused and in need of help. I built my CTH a while ago, it worked perfectly. I lent it to my dad, he accidentally plugged a γ1 into the output jack and nothing in the input jack and powered it on. It let out a puff of smoke and I assumed it was done (I found out later that the fuse wasn't blown though). Recently I've got some spare time; I figure what's the worst that can happen and run through the initial setup on the amp, and everything checks out. Questioning my sanity, I plugged a pair of tester headphones in and lo and behold, it works fine; no distortion, no channel imbalances, sounds just like it used to.

 But here's the rub; the darn thing still smells like smoke and I can't shake the feeling something's broken. The smell's only coming from the power supply section, and it seems like it might be getting warmer than it used to? It doesn't smell like burned rubber and not quite like burned semiconductor, but I understand that bits of wire can cause problems? This could very well be a case of me thinking too much about things.

 My two questions are:
 1. Could the amp have actually given up the ghost from what my dad did? 
 2. Does anyone know a good way to remove smoke smell from an enclosure?


----------



## devast

Quote:


  Originally Posted by *suicidal_orange* /img/forum/go_quote.gif 
_Thanks again Devast, expert or not your help and encouragement are much appreciated 
	

	
	
		
		

		
			





 So I measured pin 3 to SG at just 2.7V. Removed the 7824 and pin 1 to SG reads 35.7V so that's where my problem is. So in your inexpert opinion do I buy a 7824 or 3 of them, expecting it to blow again?

 EDIT: TAIWAN SEMICONDUCTOR|TS7824CZ|V REG +24V, 7824, TO-220-3 | Farnell United Kingdom <-This one looks to be suitable?_

 

Yup, thats it. Or if you have any local electronic parts store i'm pretty sure they have 7824 regulators for pretty cheap. Don't forget the insulation


----------



## devast

Quote:


  Originally Posted by *devast* /img/forum/go_quote.gif 
_Can someone do the following: do not plug headphones into the cth, set the volume pot to max, and start playing something._

 

I'd like to bump this question. After replacing q8l and q8r the the tripping happens at 14 o'clock, before it happened at 10. I don't know if this is normal. How much is the maximum DC offset of a properly functioning cth?


----------



## cfcubed

devast - I assume the query in the quote (vol max, no cans then play) is whether it trips CTH e12 (as well as the 14 o'clock question). I can try those in a day or two *but what is your source?*.. E.g. powering on or bringing an attached iPod out of "sleep" almost always caused trips for me. And tube choice, maybe even TO92 variances, can make subtle differences in tripping behavior... E.g. AFAIR for a couple non-12au7s/non-6922s I have to have cans plugged in to get e12 latch. 

 But you should not get nuisance tripping under normal usage (proper tubes, cans attached, source playing, sane listenting levels)... I don't for any of my CTHs across any of my cans & sources. 

 WRT DC offset before trip - IIRC, which I may very well not, it was tuned for around 90mV or so. AFAIR reasons for somewhat elevated & de-sensitized settings were due to component limits on 3x5 PCB involving the OB. But if you watch the offset behavior ( http://s2.photobucket.com/albums/y33...t=35a37920.flv ), once things settle down then tend to stay much below the tripping limits.
 Again, you can solder wires to relay input & watch offset WRT OG & let us know what you see.


----------



## devast

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_Again, you can solder wires to relay input & watch offset WRT OG & let us know what you see._

 

Did that, when volume is maxed i get a jumping value between -2 and 2 volts(no cans connected). My source is my notebook with volume maxed. On tuesday i'll check out with my dac, at least i know that has 2.1Vpp line out. When using my mobile phones headphone out, i have to max the volume on the CTH to get enough level, of course that way it wont trip.
 I checked out the video you linked, you get those value regardless of volume ?
 At low volume i get the same results, when i turn it up, it increases and after a point it trips. You think i feed too high signal to it and it simply trips before it starts clipping ?


----------



## cfcubed

My *DC* offset measurements were done how we normally do them, with no source connected & thus regardless of volume setting. 
 I think you may be talking common line-level / signal AC peak-to-peak levels (e.g. 2Vpp). CTH's e12 should/would trip on the DC component of its output... E.g. I'd expect 100mv DC or so to trip it. 
 Edit: But "speed"/reaction time of CTH e12 to DC comes into play as well & as you can see the cheapo meters I used for DC offset measurements are not too fast.


----------



## devast

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_My *DC* offset measurements were done how we normally do them, with no source connected & thus regardless of volume setting._

 

I was measuring the dc offset while the music is playing. Btw from this point on this test i mentioned before is just for me verifying that everything is fine, and working as intended. I can't reproduce e12 tripping with my cans connected (i don't want to endanger them, so at 13 o'clock max volume or so with my source). Thanks for you continous support! 
	

	
	
		
		

		
		
	


	



 edit: came back to the dorms, still tripping with my dac. Looks like it's heavily dependant on the source. 
	

	
	
		
		

		
		
	


	



 edit2: i also realized, that i cant measure DC offset while the music is playing.


----------



## steven2992

Hi all,
 I have nearly finished my CTH but I could only get a 100K alps pot. Does it affect sound quality? my source is a y2.


----------



## steven2992

Double post


----------



## cfcubed

> I could only get a 100K alps pot. Does it affect sound quality?

 Not as long as you have enough rotation for your listening volume(s). IOW, as long as it doesn't limit your use of the pot rotation too much, given the lowest portion of rotation is least desirable. And 150R is the max we'd like to see for the output resistors (R18s).


----------



## stringgz301

Why the limit on R18? Any other techniques for lowering the overall gain of the amp for low Z headphones?


----------



## cfcubed

Quote:


  Originally Posted by *stringgz301* /img/forum/go_quote.gif 
_Why the limit on R18? Any other techniques for lowering the overall gain of the amp for low Z headphones?_

 

Don't recall why raising R18s above about 150R was seen as non-ideal... Maybe search this thread of "150R"? Makes sense tho that one would want to use the min resistance here that makes the amp usable for them.

 Another way of lowering gain is try to stick w/the lower-gain tubes the amps supports. But in the end whatever works & sound best for you is the way to go of course


----------



## stringgz301

What about changing to a 10k pot? (sorry if this is a dumb question)


----------



## steven2992

Quote:


  Originally Posted by *stringgz301* /img/forum/go_quote.gif 
_What about changing to a 10k pot? (sorry if this is a dumb question) 
	

	
	
		
		

		
		
	


	


_

 

I could, but I've already paid 20 dollars for the 100k pot. 

 When I ordered all the parts for the CTH the relay was out of stock with a 7 week lead time, so I ordered a different one. But it doesn't fit. Does anyone have a spare that they're willing to sell me?


----------



## cfcubed

Seems I have a spare CTH relay... Fire me a PM w/your address, preferred shipping method, etc.


----------



## helzerr

Is this CTH (equipped with 12BH7A) noise floor as measured by RMAA typical?







 While I understand voltage doubler supplies like the one used for CTH's B+ may produce this sort of noise; with only ~2 mA load and capacitance multipliers I wouldn't expect this much 120 Hz and harmonics to be present at the output. Perhaps the heater supply is responsible? Thankfully, none of this noise seems to be audible through my 'phones.

 Note, this amp is built with R18=100Ω and the 330 μF C3H update installed.

 I tried another 12BH7A with nearly identical results. RMAA testing the DAC (y1) and another amplifier (Mini3) yield virtually no noise...

 In my quest to build the quietest CTH on the block, the case is grounded to the SG point and all internal signal wiring is shielded, with each shield connected to its respective signal ground at only one end of the cable to prevent ground loops - I.E. input wiring shields are tied to IG at the volume potentiometer, output wiring shields tied to OG at the output jack, and power wiring is twisted-pair...


----------



## helzerr

For comparison: RMAA results at 48 KHz / 24 bit for AMB Labs Mini3 with the same DAC (y1), same cables, same sound card performing A/D duties (M-Audio Revolution 7.1):


----------



## cfcubed

Quote:


  Originally Posted by *helzerr* /img/forum/go_quote.gif 
_While I understand voltage doubler supplies like the one used for CTH's B+ may produce this sort of noise; with only ~2 mA load and capacitance multipliers I wouldn't expect this much 120 Hz and harmonics to be present at the output. Perhaps the heater supply is responsible? Thankfully, none of this noise seems to be audible through my 'phones._

 

You may be the first to put CTH through that form of testing.
 The "fancy" CTH from my sig was built w/same motivation as yours - making it as quiet as possible. And, like your observations, I hear no noise through any of my cans. Pretty much a "black" background, at least for an amp w/a tube in it.

 Is your amp cased up? If not you could try to localize/reduce the 120hz & its harmonics you are seeing. 

 I'd not suspect the heater circuit, as it operates @ 150khz, but you could eliminate it by disabling the switcher circuit & using 6v or 12v battery to power your tube's heater. And doing measurements as well as listening tests in the comparison. IIRC, w/new C3H value & target tubes I could not discern a diff. If running tubes w/higher heater draw than we spec, raising C3H to 470uf might yield better measurements.

 You could also play around w/physical shielding (e.g. sheet metal boxing of PS sections) but, for likely the same reason you are seeing this noise, there is little room for this w/160+ parts in a 3" x 5" space. E.g. the higher noise in Right channel makes sense looking @ the proximity of the right channel parts (ICR, etc) to the PS section.

 In the end you may have to enjoy the CTH for what it is


----------



## runeight

Quote:


  Originally Posted by *helzerr* /img/forum/go_quote.gif 
_Is this CTH (equipped with 12BH7A) noise floor as measured by RMAA typical?






 While I understand voltage doubler supplies like the one used for CTH's B+ may produce this sort of noise; with only ~2 mA load and capacitance multipliers I wouldn't expect this much 120 Hz and harmonics to be present at the output. Perhaps the heater supply is responsible? Thankfully, none of this noise seems to be audible through my 'phones.

 Note, this amp is built with R18=100Ω and the 330 μF C3H update installed.

 I tried another 12BH7A with nearly identical results. RMAA testing the DAC (y1) and another amplifier (Mini3) yield virtually no noise...

 In my quest to build the quietest CTH on the block, the case is grounded to the SG point and all internal signal wiring is shielded, with each shield connected to its respective signal ground at only one end of the cable to prevent ground loops - I.E. input wiring shields are tied to IG at the volume potentiometer, output wiring shields tied to OG at the output jack, and power wiring is twisted-pair..._

 

The noise spectrum seems a bit high, but not totally unexpected. An amp like the mini3 uses a DC walwart plus IC regs to generate low voltage supplies. It is pretty easy in this case to make very clean supplies for several reasons:

 1. The actual rectifiers (and their noise) is in the walwart at the power outlet
 2. The IC regs are pretty good at ripple rejection
 3. The low voltage (16V) makes it possible to use very large electrolytics in the PS

 In the case of the CTH, in order to get the high plate voltage we need to bring AC into the enclosure for the doubler. This places all of the diode rectifiers at the back of the box instead of 6 feet away at the wall. These diodes do radiate into the rest of the circuitry. Furthermore the HV in the doubler requires HV capacitors. Hence they must be smaller in order to fit them. Finally, there is no room for IC regs and while the cap multipliers are good they are not truly active regulators and don't have as good ripple rejection.

 So while any and all amp comparisons are fair in my book, this particular comparison compares very different beasts.

 Given the original design parameters on the CTH - make a very compact tube amp where you can get 80V on the plates of the tubes from a 24V walwart along with the LV and heaters supplies some design tradeoffs had to made. The PS tradeoff is that the noise is not zero, but below audibility under normal circumstances. 
	

	
	
		
		

		
		
	


	




 Edit: What I meant to say at the beginning is that the left channel seems about right but the right channel seems too high.


----------



## helzerr

Quote:


  Originally Posted by *cfcubed* /img/forum/go_quote.gif 
_In the end you may have to enjoy the CTH for what it is
	

	
	
		
		

		
		
	


	


_

 

Yes, it's cased up and (following the advice from runeight's sig) I don't intend to modify it at this point - my concern is more along the lines of "is this normal, perhaps I botched something during the build that's leading to this noise"...

  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_So while any and all amp comparisons are fair in my book, this particular comparison compares very different beasts._

 

It wasn't my intention to compare CTH and Mini3; I was merely attempting to show my RMAA methodology was immune to noise. Regardless of the RMAA results, both amplifiers pass the comparison that _really_ counts - they are a joy to listen to!

  Quote:


  Originally Posted by *runeight* /img/forum/go_quote.gif 
_Given the original design parameters on the CTH - make a very compact tube amp where you can get 80V on the plates of the tubes from a 24V walwart along with the LV and heaters supplies some design tradeoffs had to made. The PS tradeoff is that the noise is not zero, but below audibility under normal circumstances. 
	

	
	
		
		

		
		
	


	


_

 

Since this is my first foray into tube audio, my expectations may be a little too high 
	

	
	
		
		

		
		
	


	




. Do you think a slightly larger / lower ESR C10P would help; perhaps there's a way to squeeze one onto the board? The BOM suggests UVR2C101MHD for C10P; might UCS2C101MHD, ECA2CM101, or 16x20mm (should fit in BOM case?) 150μF UCS2C151MHD or EKXG161ELL151ML20S be a superior substitute for this capacitor?

 I do not fault the design - I think it's amazing how much performance and versatility has been literally squeezed into this amplifier!


----------



## helzerr

I believe my testing method may be flawed... After much critical listening, the noise simply isn't there with headphones connected to the amplifier, even via highly sensitive (110 dB/mW) AH-C551 IEMs.

 By running the CTH output into a very high-Z load such as the line-in on the measurement sound card, the test circumstances do not mimic the amplifier feeding a normal headphone load.

 I need to build a load resistance which I can tap the measurement off of, to perform a more realistic test.

 Edit: I plan to build something similar to this headphone dummy load - http://tangentsoft.net/audio/hp-dummy.html


----------



## aphexii

Hey everybody! So i accidentally posted this in the tweak thread a week or two ago, but now i've come down to actually ordering and some of the parts have come back in stock, while others haven't (some of which are months backordered, others which have been discontinued)

 If anyone could help me figure out suitable replacements for the following, it would be greatly appreciated!!


*Mouser #:647-UVP1E100MDD*
 Mfr. #:UVP1E100MDD
 Manufacturer: Nichicon
 Desc.:Aluminum Electrolytic Capacitors - Leaded 25volts 10uF 5x11 

*Mouser #:581-BQ074E0224J*
 Mfr. #:BQ074E0224J--
 Manufacturer: AVX
 Desc.olyester Film Capacitors 100V 0.22uF 5% Lead Free

*Mouser #:511-TL082CN*
 Mfr. #:TL082CN
 Manufacturer: STMicroelectronics
 Desc.:Op Amps Dual Gen Purp JFET

*Mouser #:140-XRL100V100-RC* - Mouser suggests 140-REA101M2ABK1020P as a possible replacement
 Mfr. #:140-XRL100V100-RC
 Manufacturer: Xicon
 Desc.:Aluminum Electrolytic Capacitors - Leaded 100V 100uF 20%

*Mouser #:505-MKS4.1/100/10*
 Mfr. #:MKS4-.1/100/10
 Manufacturer: WIMA
 Desc.olyester Film Capacitors 100V .1uF 10%

*Mouser #:647-UPW1H331MPD*
 Mfr. #:UPW1H331MPD
 Manufacturer: Nichicon
 Desc.:Aluminum Electrolytic Capacitors - Leaded 50volts 330uF 10x20 20% 5LS

*Mouser #:581-BQ014D0222JDD*
 Mfr. #:BQ014D0222JDD
 Manufacturer: AVX
 Desc.olyester Film Capacitors 2200PF 35V 5%

*Mouser #:512-MPSA42*
 Mfr. #:MPSA42
 Manufacturer: Fairchild Semiconductor
 Desc.:Bipolar Transistors NPN Transistor High Voltage

*Mouser #:512-MPSA14*
 Mfr. #:MPSA14
 Manufacturer: Fairchild Semiconductor
 Desc.arlington Transistors NPN Transistor Darlington

*Mouser #:505-MKS21.0/63/*5
 Mfr. #:MKS2-1.0/63/5
 Manufacturer: WIMA
 Desc.olyester Film Capacitors 63V 1uF 5%

*Mouser #:647-UVP1C101MPD*
 Mfr. #:UVP1C101MPD
 Manufacturer: Nichicon
 Desc.:Aluminum Electrolytic Capacitors - Leaded 16volts 100uF Snap-In Audio

*Mouser #:551-EC2-12NJ*
 Mfr. #:EC2-12NJ
 Manufacturer: NEC
 Desc.:Low Signal Relays - PCB 12VDC NON-LATCH


----------



## aphexii

^ bump for assistance!


----------



## cfcubed

aphexii - This sort of thing happens in DIY - you have to work to find replacements for spec'd parts. Since CTH has so many parts, there's more opportunity for some be to discontinued or back-ordered.

 Here's ways to reduce your list, possibly to just the relay:
Use Mouser's "Show Similar" to see possible subs. Compare specs (value, rating, size, lead spacing). Values & ratings (=> spec'd rating) are important, size & lead-spacing less so. As I said elsewhere, there are pics of the completed PCB to view that may provide size guidance (some parts can be a bit larger).
If show similar doesn't, use Mouser's great searching facilities to try to ID parts w/same attributes.
Since some parts come from Digikey, perhaps look for remainder there?
If you've ordered from Mouser in the past you should have their HUGE catalog by now, using it is sometimes easier than their search.
Sometime you just need to put in the time. I've spent countless hours searching & locating parts/replacement parts using Mouser's & Digikey's searching function. My guess is you could get this list down to maybe a couple tough ones. E.g. I _think_ you can sub common dual opamps (e.g. OPA2134) for the one spec'd, same for the singles.


----------



## helzerr

I have tested a 150uF 160V replacement for C10P, which fits comfortably in the BoM case:
   
  Mouser # 647-UCS2C151MHD, 16 mm Dia. x 20 mm L, 7.5 mm lead spacing.
   
  This appears to be a worthy upgrade to the power supply components, as RMAA testing yields lower noise measurements in the 60Hz region. Probably not significant enough to bother replacing an existing C10P, but worth consideration for inclusion into any new builds.


----------



## cfcubed

That's good research & info helzerr.  I wonder if your tests would show improvement for increasing C3H beyond the BoM 330uf (low impedance).
  My testing, posted here, showed no noticeable improvement going beyond that at least for target tube heater loads.  But perhaps a 470uf 50v low impedance cap could fit there & show some measurable improvement in your tests.  With CTH's size goals more sophisticated filtering could not be pursued.
   
  And if you are up for it you could try increasing the values of the cap multipliers (c12p, c11p, etc) to see if that yields any results.  Not sure any of this will tho.
   
  aphexii - Wonder how its going w/your CTH BoM replacements.


----------



## helzerr

I may be able to locate and test replacements for C5P, C11P, & C12P.  The others are hot-glued in place as I consider the build finalized and am thrilled with its performance as-is.  Perhaps if I build another...
   
  647-UPW2A330MPD6 (33uF 8x15mm low impedance) or 647-UPW2A470MPD6 (47uF 8x20mm low impedance) look like good candidates for C11P & C12P, but 47uF may be too high a value (B+ rise may take longer than the ε12 turn-on delay with too much capacitance here unless R2P & R3P values are also lowered.)
   
  I'd be tempted to try a UPA1V561MPD (caution, part only rated 35V, application calls for 50V) for C3H if I could get my hands on one...


----------



## steven2992

I just finished my CTH and when doing the setup everything checks out okay exept the voltage across pin 1 and 6 on the tube. I get -0.6 with the red probe on pin 1. I tried reflowing components but hasn't helped. I'm a bit lost here because I was very carefull with installing the right parts.


----------



## fishski13

Quote: 





steven2992 said:


> I just finished my CTH and when doing the setup everything checks out okay exept the voltage across pin 1 and 6 on the tube. I get -0.6 with the red probe on pin 1. I tried reflowing components but hasn't helped. I'm a bit lost here because I was very carefull with installing the right parts.


 

 measure pin1 to ground and then measure pin6 to ground.  pin1 is the plate of 1/2 of the dual triode and pin6 is the plate of the other 1/2 of the triode.


----------



## steven2992

pin1 to sg measures 96.6v and pin6 to sg measures 97v


----------



## cfcubed

I guess you're past the smoke test & in this section of setup:

 Measure TB+. It should be between 95V and 105V.
 If TB+ is ok, measure pins 1 and 6 of the tube socket. These should be approximately 80V. If they are, and if the previous measurments are correct, then your amp is ready to go.
 If TB+ is wrong there is a problem in the HV multiplier. Check diode and cap orientations.
 If TB+ is good *but pins 1 and 6 are far from 80V *the tube opamps may be bad or a component value may be wrong.
 If everything in the tube circuit tests good but the plate voltages are still far off, the tube is bad.
   
  Your measurements seem high.  Are your measurements with the tube in?
   
  Perhaps you should measure TB+ to ground/SG & let us know what it is.
   
  Quote: 





steven2992 said:


> pin1 to sg measures 96.6v and pin6 to sg measures 97v


----------



## steven2992

TB+ to sg is 98.8v so it's okay


----------



## fishski13

measure/double check the value of cathode resistors, R3L and R3R?  bad tube???
   
  i want to build this amp.


----------



## cfcubed

Steven - I'm still curious if your plate -> ground measurements were with tube in or not.
   
  You do seem down to the last 2 bullets in that setup list.  As suggested, you do seem down to the Schematics -> Input Stage areas & should dbl-check components there.  If your measurements are w/tube installed they are curious as both your L & R input stages are behaving identically.  IOW, if there is a problem it seems common to both.
   
  IIRC, we did have a build diag here where one or more of the opamps were not functioning because ground pins were not soldered.  You could try using google search of this site for related keys (TB+, plate voltage, etc) to try to find diag conversations.
   
  fishski13 - Go ahead & build it   I still listen to the orig one in my avatar every work day for at least a few hrs.  Enjoy its sound & have never had any issues w/it.  Edit/note: Because I'm into keeping things cool, its in a tiny case & still has older spec'd BC550 Q1P, I've relocated its 24V reg to an external, top-mounted HS:


----------



## steven2992

measurements were with tube in. I double checked all components in the input stage and the only ones that were off were r7r and r7l which were both 8.8k when measured but they both say 1822f so the measurements are probably because they are in the circuit. everything else is correct. It could be the tube because everything else seems to work just fine.
   
  Edit: I've ordered some more tubes to be sure I have a working one. I should have them in a few days.


----------



## steven2992

All is well. It turns out I had reversed the heater switch. What I thought was 12.6v was actually 6.3v. When I put it on 12.6v the tube started glowing faintly and all the voltages were correct. It is now playing sweet music.
  Thanks for your help.


----------



## aphexii

Actually, I was able to source a number of replacement components when I was working on the list a month ago, but some recent crazyness at work pulled me away from completing the order. Things have finally calmed down to the point I can concentrate on sourcing the components again so I hope to have a more complete idea of where i'm at either later tonight or tomorrow.


----------



## MrSlim

My CTH seems to have developed a problem, hoping that someone might be able to suggest where to start looking. It starts up fine, e12 goes green, and after about 5 minutes (it varies), it trips red, then after the usual wait time, switches back to green, then back to red.. etc..   I've been using an ECC88, and have tried a new 6NP6, and a 12BH7A that I was previously using, with the same results, so I suspect its something else.. 
  Any help would be appreciated... going through HP withdrawal at work...


----------



## cfcubed

>  It starts up fine, e12 goes green, and after about 5 minutes (it varies), it trips red
   
  As you didn't mention it, I guess nothing unusual preceded this (e.g. unintended short, etc).   If this was one of our early ones are you by chance still using a BC550C for Q1P?  Way back we went BC337 for that to better handle the load. 
  And one of my CTHs had exactly the same symptoms as yours when it had a questionable Q1P.


----------



## sachu

I agree with Chris. Look at Q1P. I think yours was one of the prototypes that used the BC550 for Q1P. Replace it with the 337 and see what happens.


----------



## MrSlim

Ok.. that makes sense, since this one is the proto build I did..  I changed Q1P in the second one I made..  I'll have to see if I have a spare.. I think one of you guy's sent me one or two when I was building my second CTH and I missed it on the BOM..  Now that I'm thinking about it, is there anything else I should change while I have it cracked open?


----------



## cfcubed

If you didn't already raise C3H:
   

 C3H 1 Low Impedance Aluminum Electrolytic 330u 50V
   
  It'd be a good time to do that...   If you don't have that very one, any 250uf -> 470uf w/35V+ rating will do.  If you've room above/below board you can parallel caps to reach that.  I _may_ have a cap around & do have BC337s - PM me if you want me to check, etc.


----------



## MrSlim

I have a BC337, and I need to place an order with Mouser or Digikey in the next few days anyway, but thanks for the offer!  I'm just trying my newer unit at work and it was flipping off as well. I'm using the same transformer, could there be issues with it too? I'm going to let it run in a bit more and see if it settles down before jumping to conclusions..


----------



## cfcubed

>  I'm just trying my newer unit at work and it was flipping off as well.
   
  Heh... Your CTHs have seemed happy until now (& you with them  I'd trade out tubes & transfo just for kicks to see. 
  But you probably need to get out the DMM & *carefully *(no slip-ups/shorts - I use electrical-taped pins on my probes) check readings (e.g. running through runeights http://cavalliaudio.com/cth/main.php?page=setup setup checks). 
  E.g. regulated 24V, heater V, B+s and actual offset coming into relay (e12 sanity check).


----------



## sachu

You might want to try different wall sockets. Or run the transformer from a voltage stabilizer instead of the wall socket.


----------



## MrSlim

Yeah, I was thinking of it being a power issue.. We've been waiting for weeks to get our office cubes powered properly, and in the mean time we probably have 3 times as much load on one circuit, hanging off a bit 6 foot power bar.. Pretty bad for the IS dept of a company     Actually the newer one has been better since one of my co-workers has left for the day and powered off his systems..   Still going to make the changes though..


----------



## cfcubed

There have been questions as of late, some of which in PMs, regarding tubes compatible w/CTH. 
 The information seems scattered about this thread & the CTH "Tube & tweak" thread.  I'll try to consolidate here.
   
  Although CTH's "design center" is 12au7, it is also designed for use with other 12.6v & 6.3v (series) heater tubes having compatible pin-out/properties and has been used to good effect with them. 

*IMPORTANT*: You must always set the heater switch to the correct series heater voltage (6.3v or 12.6v) for the tube being used.
   

 *Core/main supported tube list:*
*12.6v heater:*
 12au7 variants
 ecc82
 6680
 6189
 5963
 7316
 5814
 12bh7
 8416 (12.6V 6922)
*6.3v heater:*
 6922
 6dj8
  
 *Technically speaking, we are looking for:*
 1) the 12au7 / 6922 pin-out
 2) series heater voltage of 6.3 or 12.6, prefer max series heater draw = 600ma for standard CTH builds. Tube data sheets usually list "parallel" (pins #4/#5 + #9) heater draw and "series" (pins #4 & #5 only) heater draw. Ignore the parallel figures - respect the series ones.
 3) 15 -> 40 mu (15x -> 40x amplification factor or gain). Best to stay lower e.g. < 36 mu, otherwise you may get very little volume pot range with normal/standard dynamic headphones (see also R18 info).
 4) nominal/normal plate voltage of at least 80V. Most of tubes say 100V -> 200V normal plate & that's fine.
  
 Advanced/techie/*you-are-on-your-own* list.  We began trying to compile a complete list of tubes that function in the CTH, including one with high-current and/or multivoltage heater mods.  The full list is exceeding large & our endurance ran out trying to complete it, and *we were quite happy with tubes from the "Core/main supported tube list" above*.
 Below is a pic of the first draft of the full list, note there have been more found since this sheet draft & there are European (ECC*) equivalents that could be added as well.
Dark Green rows = reported to either 1) be equivalents of known compatible tubes, or 2) been actually tested & found to work well.
Light Green rows = might work but are not sure to work & have not been tested
Yellow rows = only supported by the "multivoltage" heater mod
White rows = not yet evaluated



  
 Lots of tube preference/synergy opinion here on head-fi and elsewhere like:
http://www.audioasylum.com/audio/faq/joes-tubes.html#12AU7
http://www.audioasylum.com/audio/faq/joes-tubes.html#6DJ8 
http://db.audioasylum.com/cgi/m.mpl?forum=tubes&n=50176&highlight=sibilance&r=&session=
  
 Updates from CTH owners: _"I can vouch for the *6N1P* and *12BH7A*, both worth having (especially the 12BH7A).  6N23P-EV and 6N6P also work although IIRC the 6N6P is beyond what the Heater Supply was designed for and you need to change L1H & L2H to cope.  Heat sinking ICH was also recommended._"


----------



## Br777

^thanks for that


----------



## mugdecoffee

It would be great if that were added the the CTH main site.  I remember spending 30 minutes more than once trying to track down that spreadsheet and it'd be annoying to have it become buried again.


----------



## cfcubed

Good idea... I'll ping Alex about it for the CavalliAudio / CTH area.   The plan was to get it up there once complete.  The spreadsheet still isn't but the info we do have should be up there.


----------



## aphexii

So i'm back again, every time I planned this build months ago life got in the way. So i'm back, getting my orders ready at Mouser & Digikey and am stuck on a few key parts (and had some questions about others). 
   
  The parts that I need to find replacements for are below (no longer stocked/produced or require huge minimum quantity) - I tried finding suitable replacements using the Mouser product selector, but alas, no luck
   
   

 *[size=small]Q8L, Q8R, Q3S, Q5S[/size]*   *[size=small]4[/size]*   *[size=small]BC337-25[/size]*   *[size=small]Mouser[/size]*   *[size=small]512-BC33725BU[/size]*   *[size=small]Digikey[/size]*   *[size=small]BC33725-ND[/size]*
   

   

 *[size=small]C4H[/size]*   *[size=small]1[/size]*   *[size=small]Metalized Polyester/Polypropylene
 Film Capacitor 2.2nf 35V[/size]*   *[size=small]Mouser[/size]*   *[size=small]581-BQ014D0222JDD[/size]*
   

   

 *[size=small]D5H[/size]*   *[size=small]1[/size]*   *[size=small]1N5820[/size]*   *[size=small]Mouser[/size]*   *[size=small]863-1N5820G[/size]*   *[size=small]Digikey[/size]*   *[size=small]1N5820FS-ND[/size]*

   
   
  Additionally, can anyone point me to a good power supply that would work for this build on either Mouser or Digikey?
   
  One last question - Is there any reason the Diode's are so expensive? Is there any suitable less expensive replacement? The ones below clock in a $4.95/each
   

 *[size=small]D1L, D1R[/size]*   *[size=small]2[/size]*   *[size=small]2.0mA CRD[/size]*   *[size=small]Mouser[/size]*   *[size=small]610-1N5305[/size]* *[size=small]D2L, D2R[/size]*   *[size=small]2[/size]*   *[size=small]4.3mA CRD[/size]*   *[size=small]Mouser[/size]*   *[size=small]610-1N5313[/size]*
   
   
   
  Thanks in advance for any help you guys/gals can provide! It's greatly appreciated!


----------



## sachu

replacement parts
   
   

 863-BC337-25ZL1G
  863-1N5821G
   
  505-FKP22200/100/5
   
  The expensive CRDs deter simple cloning of the circuit by chinese markets I think.  There is no drop in replacement for it.


----------



## aphexii

Awesome, thanks a ton!!! 
   
  Any recs on a power supply? I can run by my local electronics shop where they sell ones for ~$20, but its hard to make it there during business hours (they close at 4pm)


----------



## sachu

this should do
   
http://www.mouser.com/ProductDetail/Triad-Magnetics/WAU24-1000/?qs=sGAEpiMZZMtpkqKkT5w3uqDKK8oOgNqon7/yGA1hZqU%3d


----------



## aphexii

Quote: 





sachu said:


> this should do
> 
> http://www.mouser.com/ProductDetail/Triad-Magnetics/WAU24-1000/?qs=sGAEpiMZZMtpkqKkT5w3uqDKK8oOgNqon7/yGA1hZqU%3d


 

 Rock on, thanks!!


----------



## cfcubed

Ooo.  Sachu that's a nice fine.  AFAIR I spent quite a bit of time trying to find such an animal for < $20 new & could not (except some silly ones w/screw terms - no cable).
   
  Obvious, but just make sure the associated PCB mount jack matches the plug on the A/C adapt (see its datasheet for precise details).
   
  BTW I've been quiet around here because I've reached my personal audio nirvana using CTH->new HD600s @ work and my budget ß22->600R-DT880s @ home. 
  And getting 2X 24VAC wallwarts for < $25 helped make that budget ß22 happen.
  
  Quote: 





sachu said:


> this should do
> 
> http://www.mouser.com/ProductDetail/Triad-Magnetics/WAU24-1000/?qs=sGAEpiMZZMtpkqKkT5w3uqDKK8oOgNqon7/yGA1hZqU%3d


----------



## aphexii

Darn, the MKS2-.1/63/5 were supposed to arrive back in stock at mouser on 9/15, but now thats been pushed to December.
   
  Is http://www.mouser.com/Search/ProductDetail.aspx?R=MKT1817510064virtualkey61310000virtualkey75-MKT1817510064 a suitable replacement for it? Or would you guys recommend anything else instead?


----------



## sachu

umm the link is to a 1uF cap..the Vishay one i mean. The wima is for a 0.1UF


----------



## aphexii

Quote: 





sachu said:


> umm the link is to a 1uF cap..the Vishay one i mean. The wima is for a 0.1UF


 

 Yikes, i think I need to put on my glasses this time of the morning


----------



## aphexii

(deleted)


----------



## aphexii

Wow, I must be half asleep today. My bad.
   
  This is the one that still isn't in stock: MKS2-1.0/63/5
  And this is what i was thinking to replace it with: 

 MKT1817510064


----------



## sachu

lol and here i thought i was having insomnia..still can't seem to go to sleep..
  yeah..that should work as a sub for the wima.


----------



## aphexii

haha, thanks! 
	

	
	
		
		

		
			





 lol


----------



## stringgz301

Ok all you CTH guru's.  I need some troubleshooting help.  My CTH has been on the shelf for a few months and I'd pirated a few parts from it for other projects.  After reinstalling Q4P, C4L/R, and R18L/R and installing a new pot, it powered up fine, e12 went green, and all test voltages are as per the CTH setup page.  However, when I plug in phones I get constant fairly strong white noise (I can hear music playing but not very strong).  The white noise is there with and without a source connected, and doesn't change with the pot volume.  It is independent of the tube (tried 3 different ones) and the phones (although all my phones are low Z or iems).
   
  Any ideas where the white noise could be coming from?  It was working fine a few months ago with no noise.
   
  Thanks.


----------



## cfcubed

While thinking you're reaping what you sown, my bet would be the C4 connections. The only time I've had everything green/good & got relatively constant noise in the output was after rolling C4 caps w/o solid connections for them.  Do that enough and the pads/traces may go bye-bye & you have to solder cap leads to more sturdy places (e.g. one side directly to tube socket pins). 
  
  Quote: 





stringgz301 said:


> I'd pirated a few parts from it for other projects.  After reinstalling Q4P, C4L/R, and R18L/R and installing a new pot, it powered up fine, e12 went green, and all test voltages are as per the CTH setup page.  However, when I plug in phones I get constant fairly strong white noise (I can hear music playing but not very strong).


----------



## aphexii

Everything arrived! Started populating the board tonight, hoping to make good progress this weekend.
   
  Noticed something when I came to R13L/R13R  - the BOM calls for the following;
   

 *[size=small]R13L, R13R[/size]*   *[size=small]2[/size]*   *[size=small]1/2W 1% Metal Film Resistor 1.5kΩ[/size]*   *[size=small]Mouser[/size]*   *[size=small]71-CCF55-1.5K[/size]*
   
  However, the part number listed is for a 1/4W resistor -   http://www.mouser.com/Search/Refine.aspx?Keyword=71-CCF55-1.5K
   
  Is this ok?


----------



## Forte

They are fine. The description reads *"Rated to **1/2**watt*"


----------



## aphexii

Ahhh, sorry about that, didn't even see it, Thanks!!

 I'm actually a little worried how bad my reading comprehension is lately.


----------



## stringgz301

Quote: 





cfcubed said:


> While thinking you're reaping what you sown, my bet would be the C4 connections. The only time I've had everything green/good & got relatively constant noise in the output was after rolling C4 caps w/o solid connections for them.  Do that enough and the pads/traces may go bye-bye & you have to solder cap leads to more sturdy places (e.g. one side directly to tube socket pins).


 

 That's what it was.  Bad C4 connection.
   
  Thanks!


----------



## cfcubed

@*stringgz301 *- Great to hear its fixed.
   
*@aphexii *& any other builders - Obvious but perhaps more important in the CTH case, double- (or triple-) check component values, position/placement and soldering. 
  Extra time spent upfront could really pay off compared to trying to trouble-shoot such a compact design.  And be very careful with probes when making any measurements. I used pins masking taped to mine.
http://cavalliaudio.com/cth/main.php?page=instructions/assembly
http://cavalliaudio.com/cth/main.php?page=setup


----------



## jezz

I've been fiddling and fiddling and finally got the darn thing working perfectly. Oh wait, let's just rewire it so it looks nicer. --pop-- goes the fuse.
   
  I'm pretty sure that the LED leads were shorted to ground (it worked until the epsilon22 went green, and had been working fine prior to me playing with it). Now, when I power on the amp, the red LED never lights and the green one is dimly lit, followed by the green LED lighting up properly. Out of curiosity and fear I desoldered the red LED and unfortunately pulled the lead out of the LED, which didn't fix anything.
   
  The voltages involved are: 1.8V -> 2.1V across green and 24V -> 0V across red with no red LED connected . My hunch is that I blew Q4E and maybe Q5E. The base of Q4E goes from 23.5V (triggered) to 23.9V (safe). I think Q3E is still fine because the relay still triggers correctly.
   
  Unfortunately, I just moved and am still unpacking my electronics supplies; I think I have spare BC560's somewhere, but before I go digging (or put my mouser order for a second bicolor LED), I'd appreciate someone letting me know if it sounds like I blew Q4E, or if I destroyed the amp entirely or something. Does this sound right? Or am I being really dumb right now (barring rewiring when it wasn't strictly necessary)?


----------



## runeight

Try replacing Q4E and Q5E. You may have damaged other components, but I don't think so.


----------



## jezz

Thanks runeight; doubly so, once for corroborating my mistake and another time for an amazing feat of engineering. You put an outrageous number of through-whole components in a very small space.
   
  I'll post here when I get it fixed. It might be a while; I have a few other projects that I planned on ordering parts for and I'll probably to batch the replacement LED and them into one purchase.
   
  EDIT: I should add that the amp actually does work fine right now, and the state of the LED and Q4E+Q5E makes it such that it looks basically like it used to, except no red LED while starting. The green LED isn't bright enough while it starts to shine through the tube.


----------



## aphexii

Quote: 





sachu said:


> replacement parts
> 
> 505-FKP22200/100/5


 

 Is it ok that the replacement is rated at 100v when the BOM calls for a 35v part?
   
  EDIT: Ahh, thats what it's rated UP to, so I should be fine I see. Learning as I go


----------



## sachu

yeah..its rated for a higher voltage..so am sure it'll do ok at a lower voltage. I was mainly looking for lead spacing and capcitor type when searching for a replacement.


----------



## aphexii

Quote: 





sachu said:


> yeah..its rated for a higher voltage..so am sure it'll do ok at a lower voltage. I was mainly looking for lead spacing and capcitor type when searching for a replacement.


 

 Darn, it actually looks like that replacement is a bit too thick to fit in there and covers the hole directly above it. (see image below). Looks like i'll have to find something else for C4H. 
   

   
   
  edit: Found one at Digikey that might work - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=399-5435-ND


----------



## sachu

oops..didn't cehck the width on the one i suggested. sorry.
   
  yup..taht one from digikey should work


----------



## aphexii

Quote: 





sachu said:


> oops..didn't cehck the width on the one i suggested. sorry.
> 
> yup..taht one from digikey should work


 

 No worries at all, I appreciate all the help!!


----------



## cfcubed

Aphexii - If all you need is a C4H fire me a PM w/your address.  I've an extra I could send gratis.
   
  For me the 2 most stressful parts of a DIY project are 1) applying 1st power, and 2) finalizing the parts list & pressing "Submit Order"
	

	
	
		
		

		
			




   
  Quote: 





aphexii said:


> Looks like i'll have to find something else for C4H.


----------



## sachu

^^ am there with you Chris lol


----------



## aphexii

Quote: 





cfcubed said:


> Aphexii - If all you need is a C4H fire me a PM w/your address.  I've an extra I could send gratis.
> 
> For me the 2 most stressful parts of a DIY project are 1) applying 1st power, and 2) finalizing the parts list & pressing "Submit Order"
> 
> ...


 

 Rock on! I have a few other parts i'm gonna order from mouser, but the C4H is the only one i would need from Digikey so if you have one to spare and wouldn't mind, that would be absolutely fantastic! Thanks a million!  Oddly enough Mouser shorted me on another part (Ordered 8, bag said quantity 8, but only 7 were inside), while others ended up with one extra part over the ordered quantity. First time i've had any order issues with mouser, then again this is only my 3-4th project. 
   
  Came across another question for C5P & C10P. After reading the site regarding C5P/C10P placement, where it recommends mounting them closer to the center of the board, I got a bit confused by the negative marking in the picture below. Using the picture below for directional reference, Is the far right always positive and I can select either of the other two for negative? (either the one marked with the purple arrow or the far left)


----------



## ShinyFalcon

The minus is on the pad that is attached to the ground plane. The two pads joined together are both positive. That minus marking is at the wrong spot.


----------



## cfcubed

Respect the "+", looks like all electrolytics around the perimeter of the board have their positive leads to outside of board:
http://cavalliaudio.com/cth/main.php?page=boards
  Edit: ShinyFalcon beat me to this - Yes negative ground plane.
   
  No prob mailing you that C4H in regular envelope, just PM your addr.


----------



## aphexii

Thanks again everyone for all the help!!!
   
  Very happy with my progress today!


----------



## aphexii

ARGH!!!! SO CLOSE!!! So the one part Mouser shorted me on was the 299-6.8-RC (bag said quantity 8, but there was only 7 inside), and as luck would have it, its on a 3 month backorder now.
   
  Not having much luck at all finding a suitable replacement at Mouser, anyone know of a Digikey part that might work?


----------



## sachu

Send me your address via PM, i should have a couple that i'll drop in the mail for you today.
  If ther eis anything else missing let me know quick. Will throw in a NOS Triad 6GU7 and a used 6CG7 to use in the amp.


----------



## aphexii

Wow you guys are amazing! Can you both PM me your e-mail addresses so I can pay you back for your time & expenses?


----------



## sachu

Its in the mail Josh but forgot to send out the tubes. Will do that on wednesday.


----------



## aphexii

Can't tell you how much I appreciate you guys! Thanks again!!
  
  Quote: 





sachu said:


> Its in the mail Josh but forgot to send out the tubes. Will do that on wednesday.


----------



## aphexii

Just curious - Has anyone designed any front panels with front panel express for the BOM case? Was about to start building one and figured i might as well ask first before I begin


----------



## aphexii

No worries about the front panels, had some free time so I threw something together that should work great.
   
  Another question - I think the power switch I bought is gonna be too big to squeeze in on the back of the amp (i'm planning to mount the input jack, fuse holder, heater switch and power button on the back if I can). In an effort to shrink things up a bit, would a mini SPST toggle switch like this work for power? http://cgi.ebay.com/3-each-NEW-SPST-Mini-Toggle-Switch-6a-125V-msrp-6-00-/250704121030?pt=LH_DefaultDomain_0&hash=item3a5f214cc6#ht_500wt_1156


----------



## jdkJake

I would not use anything rated less than 10A for AC Power. 15A to 20A would be a whole lot safer.
   
  Head down to Rat Shack and see if they have something that fits the size you are looking for. Even if you end up not buying one of theirs, you get a better idea of what is available.


----------



## cfcubed

We're talking 24 VAC / 1A adapter input being switched here, not mains, so any switch rated double that or more should be fine.   No problem using minis like the one you ref'd, maybe a local store like RS has one.
  
  Quote: 





aphexii said:


> would a mini SPST toggle switch like this work for power?


----------



## aphexii

Quote: 





cfcubed said:


> We're talking 24 VAC / 1A adapter input being switched here, not mains, so any switch rated double that or more should be fine.   No problem using minis like the one you ref'd, maybe a local store like RS has one.


 

 Excellent, Thanks! just found this one at the ratshack, i'll swing by tomm - http://www.radioshack.com/product/index.jsp?productId=2062503
   
  Might just pick up the same thing in a DPDT for the heater switch. I'll have a much easier time making holes than cutting a rectangle 
	

	
	
		
		

		
			




   
  Also, i'm debating just keeping the fuse on the inside (and having to deal with opening it up if it blows) to save room on the back panel.


----------



## jezz

Quote: 





aphexii said:


> Also, i'm debating just keeping the fuse on the inside (and having to deal with opening it up if it blows) to save room on the back panel.


 


 I'd suggest doing just that. I didn't, and I find myself missing a power switch a lot. You only blow a fuse once or twice (hopefully 
	

	
	
		
		

		
		
	


	




) and switch the power switch every time you use the amp. It would probably beat plugging/unplugging the transformer or the fuse. In the computer engineering and probably elsewhere, that'd be called "optimizing the common case."


----------



## cfcubed

Yes, mini SPDT toggles can be used for both power & heater switches (just don't confuse them in use).  Internal 1A (whatever your A/C adapter is rated for) slo-blow fuse w/tails, insulated well e.g. heatshrink, should suffice. 
http://cavalliaudio.com/cth/images/CTHWiringDiagram.jpg
  The reason we do this is to avoid popping the fuse that is likely in your A/C adapter, they're nearly impossible to open w/o destroying & it's a bummer if/when you toast one by way of a 20¢ fuse.  Try to keep A/C wires short, well-insulated & against case back if you can. 
   
  BTW I choose to forgo a fuse in my "fancy" CTH, relying on the one in the A/C adapter, having the room to do neat & insulated A/C input & switching.   And having proofed the build using an external fuse first.  Not usually recommended unless you are *really* confident in the build & can afford to pop the fuse in the A/C adapter if anything goes wrong.
http://s2.photobucket.com/albums/y33/pbcubed/?action=view&current=cth_new_inside-1.jpg

  
  Quote: 





> Originally Posted by *aphexii* /img/forum/go_quote.gif
> Might just pick up the same thing in a DPDT for the heater switch. I'll have a much easier time making holes than cutting a rectangle
> 
> 
> ...


----------



## aphexii

Wouldn't two SPST switches work?


----------



## cfcubed

Oops, yes.
   
  Quote:


aphexii said:


> Wouldn't two SPST switches work?


----------



## aphexii

Quote: 





cfcubed said:


> Oops, yes.
> 
> Quote:


 


  haha, no prob. Just wanted to make sure i wasn't missing something. After i mentioned DPDT yesterday (which is what the BOM calls for), i looked at the wiring diagram you posted and figured a single on/off SPST would work fine as well.


----------



## aphexii

So as i'm sitting here browsing through the thread and looking at pictures, a newbie question comes to mind. Why do some have the ICH populated and others do not? (soldered empty pads)


----------



## cfcubed

Any/all functional CTHs have ICH populated.  Some leave large, heat-sinked comps till the end to better manage their placement/clearance in the case.  Think a few bottom-mounted the regs to raise tube's profile WRT case lid like this (note: heatsink paddles on TO92 parts in pic below are totally unnecessary, I just have a thing for heatsinks):
http://s2.photobucket.com/albums/y33/pbcubed/?action=view&current=cth_inside.jpg
  but its easier to just get a "socket saver" to raise tube (like pic in my post a couple up).


----------



## javaboju

Hi all,
   
  I attended the 2009 Rocky Mountain Audiofest and got the opportunity to listen to one of these amps in the headphone exhibit.
  I believe a guy from Spruce Canyon Labs was there showing it off.  Well I took the information down and had planned to purchase a kit from the Spruce Canyon website and build one of these.
  Alas, procrastination struck again and now when I try to find the kit, I see it may not be available.
  So, I am wondering how to get a hold of one of these PCBs.
  I see I can get a BOM off of the Cavalli site and can probably get the parts from mouser or digikey.
  But I don't see where I can get a PCB.
   
  Any help is appreciated.
   
  Thanks,
  Bob


----------



## sachu

^^ Read Dr. Cavallis website more closely and you will see that PCbs are available direct from him.
  Send him a PM here on the forum requesting a PCB.


----------



## javaboju

Thanks sachu,
   
  I looked on the Cavalli website, but couldn't find a contact, email or phone.
  I am assuming that the user 'runeight', is Dr. Cavalli, since he started this thread.
   
  Let me know if that's incorrect.
   
  Thanks,
  Bob


----------



## aphexii

Quote: 





javaboju said:


> Thanks sachu,
> 
> I looked on the Cavalli website, but couldn't find a contact, email or phone.
> I am assuming that the user 'runeight', is Dr. Cavalli, since he started this thread.
> ...


 
   
  You are correct; however, he asked me to email him in regards to the boards. YGPM.


----------



## cfcubed

You will find his direct email in this post http://www.head-fi.org/forum/thread/497255/exstata-boards#post_6711588


----------



## xxbaker

I put together a CTH and everything seems fine except for the relay circuit.  It cycles on and off even though there isn't DC offset (verified by checking L and R outputs from amp section to relay circuit).  Does anybody have operating voltages for the circuit? I checked pins 4, 6, and 7 on ICE and they seem to be inline.  This was from AMB's site.  The rest of his setup procedure isn't really relevant due to the change in circuit.  At the bottom it mentions that if R5-R8 are increased in value it could stop the relay from oscillating, but I see in the revised circuit the sensitivity has already been decreased. Any ideas?  I'll keep poking around and see if I can find anything.  Thanks.


----------



## cfcubed

When you say there isn't DC offset, do you mean its really low like < 10 mv ?   IOW, could you give a bit of specifics there, like its DC offset readings.
   
  It's usual for cold CTH's to take 10 secs or more  to drop low enough to get relay latch.  Just curious if the amp is behaving as expected, e.g. you should see DC offset, even if in mV range, for a few secs from cold.     Also, do any of your parts vary from the BoM?


----------



## xxbaker

Well there is while it's warming up, maybe like 15 seconds it'll kinda jump around, but after that it'll settle down to 1mV or less.  I left the amp on for a few minutes and the relay never stopped oscillating even after it sat for minutes.
   
  I have a couple different resistors and caps in the power supply, but they're all the right values.  None of the transistors are changed and everything in the E12 circuit is from the BOM.


----------



## cfcubed

OK, your description of DC offset behavior sounds fine to me - Some moving around then settling down after 10-15 secs.
*Edit:  I assume you've no load/no headphones attached during your tests, do you still get cycling with test headphones connected?*
   
  Don't think I can help much here, I've not run into problems w/CTH's e12 implementation latching that could not be traced to somewhere else in the amp.  We've had occasional trouble w/large C4s on long leads causing the e12 to cycle.  IIRC one theory was that the electronic "pulse" emanating from the relay latching action was being picked up & causing trips.  Not sure that theory panned out.  IIRC, properly fitting the C4s on shorter leads & steering clear of some large, esoteric C4s "solved" this.
   
  I can only think double-checking e12 portion parts & orientation and considering swapping its semiconductors. And reporting any differences in expected setup readings:
http://cavalliaudio.com/cth/main.php?page=setup
   
  Perhaps others have other ideas.


----------



## aphexii

So i'm finally getting started with some case work, picked up a nice used drill press off craigslist this week.
   
  Question - In reference to the Star Ground - How are you connecting it to the BOM case? 
   
  Also, with the following diagram, looking at the pot, are those the pin outs with the pins straight up (looking at you) - Where 'top' is written throws me off
   
  http://www.cavalliaudio.com/cth/images/CTHWiringDiagram.jpg


----------



## MrSlim

Re the Star ground question, I drilled a hole in the bottom of the case for a short screw about 3/4 inch from the back, and soldered a a wire to SG from the bottom, and put a spade lug on it. Make the wire long enough to give you some slack so you can slide the board forward (before putting on the front and back panels)  and tighten the spade lug down with the nut on the screw..  Slide the board forward and you are done..


----------



## aphexii

Ahh that should work great, thanks! For now I have the SG taped tightly to the case which is sitting next to the board (figured it would be easier to test out of the case). Now time to troubleshoot following the instructions on Cavalli's site
   
  Turned on the amp for 2 minutes, no smoke, both the green and red led's lit for e12, then the red led (LED2) turns off about 10-15 seconds in (normal?) However, i'm only measuring 3v across SG/OG, so i assume something must be shorting?


----------



## cfcubed

Did the amp work before case up?     You should test an amp on the bench before casing it up - its easier to do & it let's you know when any problems originated (e.g. worked pre-casing)
   
  You will need to go through Setup & find all your Vs that deviate from it:
http://cavalliaudio.com/cth/main.php?page=setup
  Be careful doing this, I tightly tape pins to my probes leaving only the very tips exposed.  Do this w/PCB out of case of course.
   
  BTW one basic thing is* OG is NOT =  SG *(headphone must not be grounded to case...), so you may 1st want to make sure of this before pulling the board (OG-SG ohms) & checking all your setup measurements.


----------



## aphexii

Quote: 





cfcubed said:


> Did the amp work before case up?     You should test an amp on the bench before casing it up - its easier to do & it let's you know when any problems originated (e.g. worked pre-casing)
> 
> You will need to go through Setup & find all your Vs that deviate from it:
> http://cavalliaudio.com/cth/main.php?page=setup
> ...


 
   
   
  Yep, i am testing the amp outside the case (just with SG grounded to the case).
   
  Just noticed an incredibly stupid mistake though - I was testing AC voltage, not DC    <homer simpson> DOH! </homer simpson>
   
  DC voltage shows a spot on 12.01v


----------



## sachu

hah!!..well post some pics man if you got it all cased up andworking. Been a long time coming this build.


----------



## aphexii

Quote: 





sachu said:


> hah!!..well post some pics man if you got it all cased up andworking. Been a long time coming this build.


 

 Will do! Gonna do my best to have it all cased up this afternoon, just need to drill through the case to mount the SG (as mentioned above).


----------



## aphexii

it lives!!! wow, this sounds absolutely amazing!!!! Currently running it with a 12BH7A with my ATH-ESW9's, have a few different tubes i'm gonna roll in tonight and see which i prefer. Thanks again for all the help everyone!!! Especially sachu and cfcubed for sending the extra parts, can't tell you how much i appreciate it!!
  Pics coming soon, just need to screw on the endplates rather than use the plastic caps 
	

	
	
		
		

		
		
	


	



   
  BTW - Hope not to jinx it, but this is my FIRST build where everything worked after the first try without needing to do any tweaking/resoldering (6th or so build overall, MiniMAX, Mini3 and a few Cmoys)
  EDIT: Noticing a very very slight buzzing on the left channel now that its all buttoned up when the volume over 50% on all the tubes, i have a feeling its something rubbing inside the case, there sure is very little room for everything to fit 
	

	
	
		
		

		
		
	


	



   
  Rolled in a RCA Clear Top 12UA7


----------



## cfcubed

Good to hear its working & glad you are liking it.


----------



## laduq

Hi-
   
  I've just completed putting the CTH board together, and I've got two separate problems. In finishing the setup tests, all pass except going between pin 1 of the tube and the star ground, which is 99.3 volts. The voltage between pin 6 and star ground is 83.6 volts. I'm not sure how big of an issue this is.
   
  The bigger issue is that I'm only getting sound through the left channel, I get no sound through the right channel. Any suggestions on debugging this? The one channel sounds great, but I think I want them both.


----------



## laduq

I've found that if I turn the sound up very loud, I do have some sound coming through the right headphone, which I thought was completely dead. It's low but it is present. I'm not sure if I should look for a bad component, or a bad ground...


----------



## cfcubed

At one time I knew a bit more about this, and others (e.g. runeight) would be better to assist w/HV issues in this amp, but here's my thoughts...
   
  The difference in your plate voltages is not good.  AFAIK they should be within a couple/few volts of one another & around 80V-85V.  Not up around 100V (B+ / TB+ which I guess is measuring 99.3V for you).
  This problem _may_ be contributing to the lack of sound in one channel as well.  When we look at the input stage schematic:
   
http://cavalliaudio.com/cth/main.php?page=schematics/ipschematic
   
  We see that D1L & D1R in conjunction with cathode parts (R3s, R4s, ICL/ICR) should make your plate Vs in the desired 80s range (pins #1 & #6).  You should review the solder joints, parts, parts orientation, etc, e.g. reflow joints in the faulty input stage.  Comparing resistances at like points between your L & R stages, with amp powered off,  may show something.  Could try swapping tubes too as part of this just for kicks.
    
  Quote:


laduq said:


> I've just completed putting the CTH board together, and I've got two separate problems. In finishing the setup tests, all pass except going between pin 1 of the tube and the star ground, which is 99.3 volts. The voltage between pin 6 and star ground is 83.6 volts. I'm not sure how big of an issue this is.
> 
> The bigger issue is that I'm only getting sound through the left channel, I get no sound through the right channel. Any suggestions on debugging this? The one channel sounds great, but I think I want them both.


----------



## aphexii

Quick Question - Does anyone else get a pop/click in their headphones when shutting the amp off? I can see the headphone protection circuit come on for a split second before the power dies, but is the pop normal?


----------



## Forte

Quote: 





aphexii said:


> Quick Question - Does anyone else get a pop/click in their headphones when shutting the amp off? I can see the headphone protection circuit come on for a split second before the power dies, but is the pop normal?


 

 Yes, quite normal.


----------



## cfcubed

Yes, the pwr-off click/pop is normal for CTH.  It's been talked about here, somewhat irritating but should be harmless.  I just remove cans from my head before pwroff (on CTHs other than ones w/the mod talked about here:
http://www.head-fi.org/forum/thread/417322/cavalli-compact-tube-hybrid-cth-tube-tweak-thread/555#post_7026098
  )
  Quote: 





aphexii said:


> Quick Question - Does anyone else get a pop/click in their headphones when shutting the amp off?


----------



## javaboju

Hi all,
  I got my board and have ordered and received most of the parts.  There is one transistor though that is back ordered on Mouser as well as Digikey.  Does anyone know of a possible other source?
  The part is this one, the Fairchild BC33725BU, NPN, according to the BOM, 5 of them.
   
  I am a newbie as far as tubes go too, so was wondering what are the best options for acquiring a couple of tubes to try with the amp when I finally get it built.  I bid on a couple on ebay, but not knowing the worth of them bailed on the auction at the last minute.  A friend suggested trying Audigon.  Your help in this region is greatly appreciated.
   
  Thanks ahead of time.
   
  Bob


----------



## cfcubed

After today's NYC meet I can take a look for the BC337s... I probably have them.  Could then get a care package w/a spare tube out to you


----------



## javaboju

Cfcubed you rock!
  Let me know if you had any success with the npn's and I will shoot you my address.
  Plus let me know what I can pay you for them.
   
  Thanks,
  Bob


----------



## cfcubed

I've 5 spare BC337s and a 12au7 I don't need (if you need one for testing).  PM me your address & I'll get 'em out to you gratis.
  The tube isn't one of the favorites from Tube & Tweak thread, for those I use ebay, but it works fine & should give you a taste of the amp.


----------



## javaboju

PM sent.
  Thanks again.
   
  For tubes on ebay, what are some of the favorites and what is the typical price range?
   
  Thanks for all the help.


----------



## mikelikespie

Sorry if this is a dumb question, but I can't figure out for the life of me where to find the PCB for sale.  All I can find is "Boards for the CTH are available from Cavalli Audio" on its homepage.
   
  Thanks,
  Mike


----------



## holland

Quote: 





mikelikespie said:


> Sorry if this is a dumb question, but I can't figure out for the life of me where to find the PCB for sale.  All I can find is "Boards for the CTH are available from Cavalli Audio" on its homepage.
> 
> Thanks,
> Mike


 


  that's not a dumb question, there's no contact link i could find neither.  Send runeight an email via head-fi.  runeight is Alex Cavalli.


----------



## holland

Quote: 





laduq said:


> I've found that if I turn the sound up very loud, I do have some sound coming through the right headphone, which I thought was completely dead. It's low but it is present. I'm not sure if I should look for a bad component, or a bad ground...


 


  Are you still having problems, laduq?


----------



## forsakenrider

So, Finally its my turn to come back to this forum for help, it's been a long while and I've had a busy summer with cycling.
   
  Heres the story, a few weeks ago I got my hands on some Shure E2C iem's, I was listening with my CTH and noticed some hum, so I figured now would be a good time to change that Cap (C3H). At the same time I also changed the output resistors (R18R, R18L) to 100ohm. The only 330uf 50v capacitor I could find was a little large so I left the leads a little long, all went well. Powered it on and it seemed like all was fine and dandy, the hum was basically gone. I listened to it for a few hours that night (this was saturday) I listened a bit more on sunday and the amp was basically on for 10 hours yesterday, no problems! Today I plug in the amp and FLASH! the red LED flashes and goes out, the e12 never switches... I swap out the dual LED for one green and one red, still nothing. I tried a different tube, still nothing.
   
  TB+ - 129.7v
  PIN1 - 47.9v
  PIN6 - 45.7v
  OG - 0.109v
   
  Any Ideas?


----------



## cfcubed

Wow, long time no hear from Mr. CTH Proto PCB #2 
  When you say FLASH do you mean SPARK (e.g. fireworks of some kind)?    Think there was a short?
  All those Vs seem off to me (not close to setup Vs below).   All of these are WRT *SG* right? 
   
  How about crawling though Alex's setup measurements http://www.cavalliaudio.com/cth/main.php?page=setup and listing your results here.
   
  The basics of which are trying to do these things:
  1)  check your LV 24VDC supply - you can do this on the output pin of the 24V reg (between middle pin & pin labeled "O" here: http://www.cavalliaudio.com/cth/main.php?page=boards)
  2)  check the rail splitter is creating a virtual ground @ 1/2 of LV (12V OG-SG difference)
  3)  check that your HV - approx 100V TB+ is being brought down to approx 80V on plates
   
  What A/C reading are you getting at the wallwart in?   I ask because your TB+ of 130V is about 25% higher than expected.
*Be very careful making these measurements (e.g. pins taped to probes).*  I blew an OB once by shorting while taking measurements.


----------



## holland

hey forsakenrider!  double checking the setup voltages would be a great start.  Your voltages are way off.  The e12 is probably tripped and will never turn on.


----------



## forsakenrider

I dont think it was a spark, I was running with an 8416 tube and they light up when first powered on, The led seemed brighter then normal but it was just a flash, and thats what caught my eye. I didnt see smoke or fire and didnt smell anything off.
   
  First off my wall wart is reading 31.9vac, Im not sure if its always read that or is thats new. I vaguely remember my HV being on the higher side but everything else being correct before, so It was probably always that.
   
  all my measurements before were WRT SG
   
  The LV supply is 0.8v, That cant be good.


----------



## holland

Quote:  





> The LV supply is 0.8v, That cant be good.


 
   
  Nope, not at all.  If you can, probe the points right after the rectification on the LV.  Your plate voltage is way too low, should be ~80V.  The CCS for the tube (opamp) should have ~2.5V on it's pins (in and out). 
   
  Test the voltage after the 24V reg, C1P or C2P leads would be a good point to probe on the underside.  If it's dead, test after the rectifier, and then test after the cap multiplier to see which building block is dead.  I would be surprised if the diodes fried, but I wouldn't be surprised if the reg or the cap multiplier died.


----------



## cfcubed

Yep, as holland says let's figure out / fix that LV supply first.  Doing that may fix the other voltages.  I guess its OK that your wallwart is high if its the same wallwart you've been using all along.
   
  Like he said, lets see the Vs around your 24V reg.   Another place to probe test points is on the reg itself.  Again, see the *O*utput, *-*/center and* I*nput labeling here http://www.cavalliaudio.com/cth/main.php?page=boards and let's know what the input & output Vs are on the reg WRT its center pin.
   
  Again as holland said, a weak link in the original BoM was Q1P... Originally a BC550 it was changed to stronger BC337.  If input V to 24V reg is low measure your collector & emitter Vs on Q1P.  All this WRT SG.    BTW, if you need a BC337 I've plenty & could post one to you.


----------



## forsakenrider

The LV supply is 44.5v  (at c5p's +)
   
  Q2P C=45 B=41 E=44.2
  Q1P C= 45 B=44.4 E=0.2
   
  So I guess its Q1P, I will have to look but I doubt I have any BC337
   
  what could cause that? Did it just die eventually?


----------



## cfcubed

We saw some Q1P BC550 failures over time (within 1st 4-6 months?) & it became clear BC337 was a better choice there & we updated the BoM. 
  Hotter caused earlier failure & w/your 24V reg having to pull down so many volts that's more heat.  Is that 32VAC under any load?  It should not be higher than 28VAC under load.
   
  If you've a BC550 around you could put it in just to confirm that's all that's wrong.  If you've one of those TO92 paddle heatsinks around that would help it (probably why my 1st proto w/BC550 is still fine).  
   
  PM me your address & I'll drop you a couple BC337s
  Quote: 





forsakenrider said:


> The LV supply is 44.5v  (at c5p's +)
> <snip>
> So I guess its Q1P, I will have to look but I doubt I have any BC337
> what could cause that? Did it just die eventually?


----------



## forsakenrider

I just plugged the wall wart in for a minute and it seems around 28vac after a minute. At first it dropped down to 24 and raised up it slowed around 28. I hope its not too extreme! I did run it for an entire day just before it died, maybe it was just its time to go...


----------



## holland

Wallwarts shouldn't die like that.  I have mine on quite a bit.  It's my office rig, so it's on pretty much 10 hours a day.  28VAC is fine, but the rise is odd.  It could be your mains is dipping and rising.  That's not unheard of in older areas.


----------



## cfcubed

Thought I'd post this somewhere...  At the start, the prime CTH goal was a through-hole, full-featured hybrid amp in as small form-factor (case) as possible.   So some earlier ones were made w/small pots & stereo mini (1/8") jacks like my current avatar. 
  Well those little jacks & plugs are really a weak spot... Mine started getting dodgy & I was using a hokey 1/4"/1/8" adapter for my new cabled HD600s.  So I took care of that tonight:
   

   
  I'd pulled the 24V LV reg out & gave it that cool heatsink a while back as I'm a heatsink fan  The new wiring is more simple & shorter but did have to dremel that 1/4" jack a bit to fit.
  So its up to the task again as my @ work amp & we'll see if I get a few more years out of it


----------



## holland

That's a nice heatsink.   It must be a really tight fit now.


----------



## cfcubed

>  It must be a really tight fit now.
   
  Not _that_ tight, but maybe I'm used to packing things in.  The RCAs fit right where the stereo minis were & the Neutrik NMJ6HCD2 right over ICE & a couple other low comps.  Had to rotate the jack just so, shave a bit of "extra" plastic off it & cut off its (unused) switched pin leads (to avoid shorts to case top).  No big deal really & its solid & working fine.


----------



## forsakenrider

We want inside pics!!\


----------



## forsakenrider

You DA MAN! my CTH is up and running! sounds great as ever and even ALL of the hum is gone on low Z phones. I cant here anything at listening volume even on my Yuin OK2.
   
  Now one more question, when it first happened I swapped out the dual colour LED for two single colour LED's, when I plug it in both come on (green and red) but red is the brighter of the two. When the E12 switches the green gets brighter and the red goes out. Is this normal?


----------



## cfcubed

Great its back & better.  Though I've never used individual LEDs, it seems odd that both would lite @ startup.  Looking @ "Lights" in the schematic:
   
http://www.cavalliaudio.com/cth/main.php?page=schematics/e12schematic
   
  I guess its possible a BC560 is spilling some current into the green LED prior to e12 lock.  But even my dual color LEDs look "funny" prior to lock, as if both colors are lit somewhat.  So I think its no biggie.
   
  Being overly paranoid, if you've a safe way to measure it I'd just check that your DC offset is < 50mV or so after lock (OL/OG & OR/OG).
   
  BTW I'll try to post pics in the next couple days of the inside work I talked about above.  Picture = 1000 words


----------



## forsakenrider

My offset is 7mv  it was the last thing I checked.
   
  I want a picture because I want to do the same as you for the 24v reg. Remember, I have those heat sinks too. That was actually the idea I had but there was talk about the longer leads effecting it so I never got that far...


----------



## holland

You should be able to add more resistance to the LED wiring, if it's of concern to you.  FWIW, I use a single LED and when the "red" is on, the LED is brighter.  When off, it's lower.  Details on that, hmm, I can't quite remember and I don't want to open up my case.


----------



## cfcubed

Quote: 





forsakenrider said:


> We want inside pics!!\


 
  And here you go   Since my 1st post of the 1st CTH proto PCB up & running had a playing card next to it, thought I'd do it again:
   

   
  As a heatsink fan I decided to move my 24V reg out of the case & on to that top heatsink (note: it is absolutely not necessary to do this, an internal reg + heatsink + vent holes is fine). 
  It's mounted w/its metal tab up on one of the 2 screws.   Working fine w/the short wires you see here (note heatshrink):
   

   
  Since the 1/4" stereo side jack went in the PCB no longer slides nicely out the back... Access is now by popping the ends, pulling the sides of the hammond case outward & popping up the lid (partly due to short 24V reg wires).  The TO92 paddle heatsink on my BC550 Q1P coupled w/the LV reg's heat outside the case has probably helped be avoid the change to BC337 there... I use it at least 15 hrs/week.


----------



## holland

lol, I like your cover prop.
   
  I spy fancy caps.


----------



## cfcubed

Quote: 





holland said:


> I spy fancy caps.


 
  Its all relative... Guessing you didn't see my other thread post tonight when you said this


----------



## holland

Quote: 





cfcubed said:


> Its all relative... Guessing you didn't see my other thread post tonight when you said this


 


  Nope.   Nice vcaps there.   My most "boutique" are the large m-caps in my Bijou.


----------



## steven2992

My CTH has been running for a few months and it worked perfectly except for a slight hiss. Today I tried to fix that by replacing the in and output wires with some shielded cable. When I turned it back on there was a loud hum. I tried multiple tubes and nothing changed. I've redone the initial checks and the results are: OG/OL/OR to SG 12.01V,  TB+ to SG 95V, tube pin 1 to pin 6: 00.4 and the e12 trips as soon as the probes touch the pins. My guess is that the tube opamps are blown. Am I correct?
  Also do I have to raise or lower the value of the output resistors to reduce hiss with low Z phones?


----------



## sachu

Pin 1 and 6 need to be measured with respect to SG. 
   
  And when measured wrt SG, they should be identical. Also did you make sure you grounded the shield only on the source end?


----------



## steven2992

Pin 1/6 to SG is 90.5 and 90.7, The wire is 2 conductor +shield so the shield is the ground conductor. 
   
   
  EDIT: nvm, I had IR and IG reversed. My CTH works now and is playing sweet music


----------



## cfcubed

>  Also do I have to raise or lower the value of the output resistors to reduce hiss with low Z phones?
   
  You raise the R18s.. Default is like 60R->100R & IIRC max of 120R->150R for them(?).


----------



## forsakenrider

Interesting cf, I woulda thought you would mount the reg to the inside of the lid for shorter wires.
   
  Heres a little double LED video action....
   
  http://www.youtube.com/watch?v=Kyf9LKy2TXQ


----------



## cfcubed

Quote: 





forsakenrider said:


> Interesting cf, I woulda thought you would mount the reg to the inside of the lid for shorter wires.


 
   
  Yeah, that would be easier all around too (you could unscrew to get reg free, mine's pretty soldered).
   
  IIRC I did it this way because the very 1st rendition was using the case as a heatsink (reg was mounted to case bottom/underside of PCB) & I didn't like the way the whole case heated up.
 Note:  again I've experienced no problems w/the length wires you see.   Maybe you'll come up w/a smarter way
  Quote: 





			
				forsakenrider said:
			
		

> /img/forum/go_quote.gif
> 
> Heres a little double LED video action....


 
  Heh, it looks like you said @ startup - RED is bright (as it should) & GREEN is dim (& should be "off"),  then @ latch its all good (RED off, GREEN on).
  My guess would be questionable BC560(s) in the "light" circuit OR you have to play w/LED resistor values, as holland suggested, to get things looking as expected during startup.
  IMO the dual colors have a nice, seasonal look to them & it could take a lot of fooling around to "fix"... And we don't like "unnecessary" surgeries


----------



## runeight

This is happening because the base current in Q5E is flowing through the LED. You can reduce the base current by increasing R8E without harming the circuit. Try something like 330k or even 470k to see if this fixes the problem while still lighting the green LED bright enough when it's on.


----------



## forsakenrider

The LED doesnt really bother me, I kinda like it like that anyway....
   
  BUT! since changing to the BC337 it seems like my e12 trips WAY too easy. I try not to listen to music thats part of the "loudness war" so sometimes at listening volume there will be a loud kick drum or something and POP! trips the e12. Did the values change since the proto? I remember getting lost in the music not long after and "if it aint broke don't fix it" when there was little changes.


----------



## cfcubed

Q1P -> BC337 should not cause this.  Something else may be going on.  IIRC, yes a couple/few(?) CTH e12 resistor values were changed in its 1st couple months to the current BoM ones: http://cavalliaudio.com/cth/main.php?page=schematics/e12schematic
  A quick search turned up posts/followups like this: http://www.head-fi.org/forum/thread/398839/a-very-compact-hybrid-amp/765#post_5601943


----------



## holland

Double check that your power rails, after the BC337 change, is not fluctuating and actually regulating.  Something may have been damaged during the swap.  A fluctuating 24V will likely trip the e12.  Try a different tube also, just to rule that out.
   
  Other than the tube, I'd suspect something went amiss during the swap.  I can't recall if you swapped the regulator, but it may not be operating within it's designed parameters.


----------



## forsakenrider

I just double checked my original BOM with the recent one and HA! almost every R in the e12 was changed. I changed them all and its now able to go to ear bleeding volumes without e12 tripping. I find the cooler my amp runs the easier it is to trip the e12. I guess because some of the transistors are effected by temp. When I swapped the BC337 I added thermal paste to the 24v reg (oops) and that made a noticeable difference in temperature.
   
  So, lets re-design it for pocket sized fun


----------



## holland

LOL, now that you mention it, i think I remember the resistor changes!


----------



## cfcubed

Quote: 





forsakenrider said:


> HA! almost every R in the e12 was changed. I changed them all and its now able to go to ear bleeding volumes without e12 tripping.
> So, lets re-design it for pocket sized fun


 
  Sounds like all is well w/your CTH now.
   
  Re: re-design - Y'all may have noticed things are a bit quieter around here.  My guess is it may be a combo of there being plenty of designs to choose from & maybe efforts happening in the dark / elsewhere, which IMO is fine.  Personally, I've enough gear for 3 or 4 audiophiles
  But I'll probably not be able to resist the smell of solder for long.  E.g. it dawned on me I've never made an exceedingly simple headamp (other than may my 1st - the SOHA), like one w/a dozen or so parts per channel total.
  So kicking around the idea of trying something involving an actively loaded grounded cathode input stage (from a schematic Alex passed to me way back), an IRF510, this SMPS:
http://www.tayloredge.com/storefront/SmartNixie/DataSheets/Datasheet_1363-1364.pdf
  some other bits & a 12VDC wallwart and see what happens (perhaps not much  Someday anyway.
  ^^^^  Yeah, don't both w/that nixie SMPS for audio.  It's switching freq seems to be in the high end of audio range.  Something different might work tho.


----------



## holland

Quote: 





> Originally Posted by *cfcubed* /img/forum/go_quote.gif
> 
> Personally, I've enough gear for 3 or 4 audiophiles


 
   
  LOL!
   
  I don't even consider myself an audiophile, to be honest.  I hear you though.  I never sell anything, so I have amps galore, along with half-finished amps and amps that never made it past paper (tried to design something, but kind of lost interest in everything half-way through).


----------



## runeight

Gents, the original CTH boards have been bought up slowly over time. There are only 2 left in my inventory and I don't expect to make any more any time soon.
   
  If there are any of you out there thinking about buiding this amp now would be a good time to grab one of these boards. Please email to alex@cavalliaudio.com. Please don't PM because the first two emails that I get will get the boards.
   
  Thanks for the great run guys. This is a really nice amp. I hope you are all enjoying yours.


----------



## runeight

Gents, the boards are taken. Thanks again for building this amp.


----------



## MrSlim

Wow, as one of the original prototype group, I feel a little sad.. Is this the end of the line for this little beauty?
   
  Forsakenrider, with the density of components on the current CTH board, about the only way to  redesign would be to go SMD, and thats a hell of a lot of components to do that with, unless you've mastered the Toaster Oven or electric frypan techniques...


----------



## runeight

I don't think it's the end of the line, but the next incarnation of this amp will be in a somewhat different from with a slightly different design.
   
  You're right about the component density. It will be hard to make a smaller board unless you either go SMD or tombstone the resistors. But then I think there will be heat issues.


----------



## pterodactilo

What a pity! . I 've finished one Mini 3 and  one gamma1+gamma2 and was interested in this amp as my next DIY project. It seems like a step up from Mini 3 yet not very expensive to build and compact. Also I am very intrigued by the tubes , not to mention that they look so cool. Ok, let's wait until next desing arrives, but in the meanwhile if somebody has one CTH board left  please let me know.


----------



## sachu

the mini3 is a portable amp and for the purpose it is a great little amp...the CTH however is a very significant step up from that...i mean like seriously big step up.


----------



## Mullet

Wow. What a shame! I was just looking at building this amp. I'll have to have a look in FS forums to possibly find a board. If anyone has an extra that they'd like to part with please PM me.


----------



## cfcubed

Perhaps runeight would consider a PCB run if someone conducted a group buy and there was enough interest (handling the nasty $$ / shipping tasks).
  If that happened, "bulk" ordering of the "pesky parts" (LM2595adj, coils) & including them would be something to consider.
   
  I know he'd a rev of the board w/some improvements that might be used for future runs.  Perhaps he's also a few other changes up his sleeve


----------



## pterodactilo

Quote: 





cfcubed said:


> Perhaps runeight would consider a PCB run if someone conducted a group buy and there was enough interest (handling the nasty $$ / shipping tasks).
> If that happened, "bulk" ordering of the "pesky parts" (LM2595adj, coils) & including them would be something to consider.
> 
> I know he'd a rev of the board w/some improvements that might be used for future runs.  Perhaps he's also a few other changes up his sleeve


 
   
   You have both CTH and CKKIII amps . Which of these do you think would be best for K601 phones?


----------



## cfcubed

Quote: 





pterodactilo said:


> You have both CTH and CKKIII amps . Which of these do you think would be best for K601 phones?


 
  Can't give an *opinion* about this as I've never heard or owned K601s.  Suggest searching for your terms, using google against this site if you're not satisfied w/this forum's search. 
   
  My current preferences, w/my gear/source/music/ears/etc, are for my 2008+ HD600s w/CTH.  And for my HD650s w/β22 (big) or CK²III (small).  This may be stuff for a different thread/forum.


----------



## forsakenrider

Quote: 





mrslim said:


> Wow, as one of the original prototype group, I feel a little sad.. Is this the end of the line for this little beauty?
> 
> Forsakenrider, with the density of components on the current CTH board, about the only way to  redesign would be to go SMD, and thats a hell of a lot of components to do that with, unless you've mastered the Toaster Oven or electric frypan techniques...


 


  Well of course, I dont think it could be quite the same... But if we could come up with a pocket sized tube amp that maybe ran on some small lipo batteries (theres all sorts of rc airplane stuff these days) and used a pencil tube that would just be... too cool.


----------



## MrSlim

Quote: 





pterodactilo said:


> You have both CTH and CKKIII amps . Which of these do you think would be best for K601 phones?


 

 I have K601's, a CTH and a CK2III that I should be completing in the next week or so, so I might be able to give you my opinion then..  I've also got a Panda in the works, and 3 channel B22 for a friend (a 4 chassis Par-Metal order showed up yesterday...  
	

	
	
		
		

		
			





 )


----------



## Mullet

I've never done a group buy nor have set one up. I'm curious as to what is needed to get this done. I'm assuming one person does the initial buy and everyone else provides the money for the parts/shipping. Is this correct? I'm game to figure this out or at least facilitate the matter.


----------



## cfcubed

Quote: 





mullet said:


> I've never done a group buy nor have set one up. I'm curious as to what is needed to get this done. I'm assuming one person does the initial buy and everyone else provides the money for the parts/shipping. Is this correct? I'm game to figure this out or at least facilitate the matter.


 
   
  I've not conducted a GB either (and will soon have 3 built CTHs but you could take a look at other GBs from the Group Buy forum like http://www.head-fi.org/forum/thread/241814/group-buy-22-backplane-board-v1-1-6-5-6-17
   
  I guess the 1st step might be PMing runeight & seeing if its feasible and, if so, any particulars (e.g.minimum # of boards, who would do what, etc.) 
  I only guessed above that runeight _might _support a group buy if someone else would conduct it & he'd just do the board run, get paid, then ship the boards to whomever was doing the GB.   All of this is just imaginary conjecture right now


----------



## Mullet

If anyone is interested I'm getting an interest check on a possible group buy for the latest revision (rev 2021) of the CTH pcb. Some basic info is in this thread... http://www.head-fi.org/forum/thread/536098/ic-potential-group-buy-for-cth-compact-tube-hybrid-pcb


----------



## Forte

Quote: 





mullet said:


> If anyone is interested I'm getting an interest check on a possible group buy for the latest revision (rev 2021) of the CTH pcb.


 


  Have not heard about this revision before and do not see any mention on the Cavalli Audio site, what has changed?


----------



## Badd99

Just saying I currently use my CTH with my LCD-2 and at a mini meet the CTH stood up to me against 3,000 amps without showing many flaws....great amp!


----------



## cfcubed

Quote: 





badd99 said:


> Just saying I currently use my CTH with my LCD-2 and at a mini meet the CTH stood up to me against 3,000 amps without showing many flaws....great amp!


 
  Thank you for this...  Being involved in its dev I should not say much, but amongst the opinions you can find here by searching you should not miss the NYC meet ones.  There is always stellar (priced) gear @ those meets and its fun when folks take the time to listen to the CTHs.  A lot of good comes out of its 3" x 5" space
   
  >  Have not heard about this revision before and do not see any mention on the Cavalli Audio site, what has changed?
   
  Mullet noted a few of the changes in his GB IC & if/when that comes about I'm sure there will be more details about the latest rev.  IIRC they were not _substantial _changes, more incremental ones (e.g. incorporating a few "easy"/low-risk improvements).


----------



## civilmonkey

Although I am reviving an older thread, I'm sure with the recent group buy for PCB's people might start looking at getting their parts together.
   
  So, Mouser is out of Wima 0.1 uf polyester film capacitors (for locations C3L C3R C7L C3P C1E).  It says they should get some in soon, but if not, would I be able to up the capacitance to .22 uF for these caps.  The Wima MKS2.22/63/5T (mouser 505-mk2.22/63/5t) is in stock.  There is also the 0.1 uf 250 V version, but it is bigger in width and I don't think it'll shoehorn onto the PCB well.
   
  Mouser is also very low on BC560CG, but Digikey seems to have lots.


----------



## holland

C1E is 1U.  It is for a low pass filter.
   
  There are other poly films other than Wima.  Brands such as Kemet, and Vishay.  Wima is just a popular name.


----------



## cfcubed

Mullet, runeight & myself have a new draft BoM for the CTH PCB in that group buy.  Did have to juggle things between Mouser & Digikey & come up w/some new subs. 
  Mullet has all the parts in hand spec'd in the new BoM and we were thinking the BoM would be considered final when he builds out the 1st PCB of the latest rev. 
  I think the PCBs are due this week & think Mullet will be available to start building early next week (to fully vet the new PCB rev & BoM).
   
  The only problem with "releasing" the new draft BoM is that we cannot call it final until that 1st new rev CTH is up.  If any parts were wrong or missing it could mean costly re-orders for builders.
   
  BTW we may want to start a new thread for this new revision, perhaps when Mullet gets going next week.


----------



## Mullet

Like cfcubed already stated, I had to seek out a bunch of alternate parts because a bunch were on backorder or some aren't being made anymore. So we've put together the alternatives and I'm going to be starting the build *hopefully* on Saturday or Sunday. I have all the parts ready to go including the PCBs. Once all is tested and working, runeight will post a revised BOM. At that point, I'll begin collecting payments and shipping everyone their boards.
   
  I can start the new thread once I'm into the build and *hopefully* not having issues. But, you never know with this stuff... Stay tuned!


----------



## forsakenrider

how about a teaser picture of these new boards?


----------



## simwells

Guessing from reading recent comments if I wasn't in on the GB the chances of being able to build one of these any time soon are pretty slim? Would I be better to wait for a new incarnation that Runeight hinted at?


----------



## cfcubed

>  how about a teaser picture of these new boards?
   
  Hey forsakenrider, remember the bit o' pressure, self-imposed as it was, we were under when we were building out the 1st two CTH PCBs?   
  Well Mullet is there now w/the latest PCB rev + parts.  Sure we'll hear once there is something interesting to be told


----------



## forsakenrider

I know I know, I just wanna see this new white on black snazzzz.
   
  What about black resistors, who makes those again? I know I've seen them on someones build around here... That would sure be a nice ALT on the BOM!!


----------



## cfcubed

Quote: 





forsakenrider said:


> I know I know, I just wanna see this new white on black snazzzz.


 
  We thought it might be better to create a new DIY thread for new rev CTH PCB builders:
   
  "the CTH (Compact Tube Hybrid) Rev A thread..." - http://www.head-fi.org/forum/thread/542279/the-cth-compact-tube-hybrid-rev-a-thread
   
  A lot of the (old) issues raised in this huge thread have been addressed through parts spec changes in newer/newest BoMs & PCB layout improvements in the latest PCB rev.
   
  This is not to say CTHs using this new PCB rev will sound different/better than CTHs using earlier PCBs that have corrected parts installed (in particular 330uf C3H & BC337 Q1P). 
  The changes in this new rev are largely ones that make building easier (see the new Rev A thread for details).


----------



## WyldRage

Finally finished mine (yes, it's the original and not the Rev.A). I've had a few troubles, notably on finding a wall-wart. My first one was 24 VDC, despite being indicated as VAC. I am now using the WAU24-1000, though I've had to snip the original connector to replace it with a 2.5mm one.
   
  Now, the only trouble it has is that turning the volume pot too fast trips the e12. The pot is the alternative one on the BOM, the Panasonic EVJ. If anyone has any idea how to fix this, it would be appreciated.


----------



## WyldRage

Nevermind, I found the cause: I had linked the input jack's ground to the output jack's ground. Linking the input jack's ground to the volume pot grounds instead resolved it, and the e12 no longer trips when changing volume.
   
  I was also blowing up some fuses when inserting the power connector. I made the panels out of aluminium, and the connector was shorting to the case. I widened the hole and put a vinyl gromit to isolate the conector.


----------



## WyldRage

New update: smoke! The moment I connected it to my E-mu 0404 USB, smoke came out of something close to the ICP. There was not even any signal going in! I'll have to get replacement parts for the 2-3 transistors and capacitors there.


----------



## cfcubed

That's a shame about the smoke.  I was a bit surprised that your CTH survived the IG/SG/OG 12V dead short (OG sits 12V above IG/SG).  Perhaps that damaged something.  Maybe it was the A/C connector to case that did it.  Or maybe something is still mis-wired that caused the smoke (e.g. another ground problem aggravated by connecting 0404's ground?).
   
  Perhaps your CTH was fine on the bench, e.g. it passed your setup measurements:
http://www.cavalliaudio.com/diy/cth/main.php?page=setup
  but things that shouldn't be interconnected were (e.g. metal case + not using insulated jacks such that the wiring requirements did not hold:
http://www.cavalliaudio.com/diy/cth/images/CTHWiringDiagram.jpg)  Nothing should interconnect (read 0 ohms) except IG/SG/Case.
   
  You'll have to really check these things if replacing select parts does get your CTH going again.  Good luck!


----------



## WyldRage

Well, the crazy thing is that it still works. It's just a theory, but I think it was because I plugged the E-mu's input to the CTH's output (I was going to test it as I had done on my other amps). The very high input impedance may be drawing too much, or something like that (I don't have much of an electrical background).
   
  In any case, the CTH and the Emu don't like each other, and will no longer be connected to each other.


----------



## MrSlim

Does anyone have a listing of the changes in the E12 circuit between the original BOM(prototype time) and the most recent one (for the original circuit design, not the new Rev).  I sold my CTH and the buyer is having E12 tripping problems. I never had an issue with this but I didn't use it the same way he is.  I suspect its partly due to using Thunderpants at a high volume, with the bass eq cranked as well, and his particular choice of music (electronica).  Has the E12 circuitry been reduced in sensitivity and if so, any suggestions on what would need to be done?


----------



## cfcubed

Mr Slim - I'd have to search here myself to find it as I don't recall exactly which parts were changed & to what values.... IIRC runeight has made a post in the last 6 months or so about it so maybe search for his posts?
  Also IIRC the original BoM is up on cavalliaudio as well as the newest/latest one.


----------



## blaken

I need some help guys.  I finally got my CTH all populated and wired up but  I am having a problem.  No smoke and the LED light turns on but SG-OG is 1.3 VDC and SG-OL and SG-OR is 0.  I have no idea what to do.  I built this using a kit from Waitrob I got almost 2 years ago which I should have finished back then.  If anyone could help I would greatly appreciate it.
   
  Thanks
   
   
  Here are some pictures of the amp,
  http://i11.photobucket.com/albums/a175/bnorton/Top-1.jpg
  http://i11.photobucket.com/albums/a175/bnorton/Bottom-1.jpg


----------



## cfcubed

blaken - I assume you mean your output relay does not latch.  Key measurements for that are OL-OG & OR-OG _going into the relay_.  IOW, w/o relay latch, checks on those pads will read 0.  You could tack temporary wires to OR/OL going into the relay for this test.  Looking at the PCB relay mount, these are the middle pads of the 2 triplets:
http://www.cavalliaudio.com/diy/cth/main.php?page=boards
   
*But, before the above, the 1st steps in any debugging are:*
  1)  double-check soldering job esp. looking for bridges.  Assuming the underside has been cleaned (e.g. w/90%+ alcohol),
  2)  double-check the correct parts are in the correct places and correct orientation on the board,
  3)  Conduct the setup test here & let us know the voltage readings from it:
http://www.cavalliaudio.com/diy/cth/main.php?page=setup
  Most measurements are with-regards-to SG.   Also please let us know the heater readings (voltage bet pins #4 & #5) for both 6V & 12V heater switch positions.
  Be _very_ careful with your probes when taking these measurements (e.g. I've taped pins to mine for CTH tests).
  4)  Try to post clear/good resolution pictures of your build top & bottom


----------



## cfcubed

>  SG-OG is 1.3 VDC
   
  Though my last post should still be followed, I see this is a fail for the 1st setup test (expect close to 12V).  Let us know your ICP voltage measurements: middle pin to input pin (*I*/right on PCB image) and middle pin to output pin (*O*/left on PCB).  We should be getting close to 24VDC out of it.  If we are then there may be problem w/TLE2426/rail-splitter.


----------



## blaken

Thanks for helping CF.  I am at work right now but I will take those measurements as soon as I get home. (I should have refreshed by browser before replying I wrote all of this without seeing your second post.  I will get all the data tonight.)
   
  1) I did look for bridges but I will again.  I did clean the board with 91% alcohol and a tooth brush twice.
  2) All the orientations look good but I haven't got out the magnifying glass yet to check parts but I will.
   
   
  I want to make sure I am explaining myself as to what I was doing.  I can follow instructions and a schematic but as to what is going on where in the circuit I am clueless.  I was trying to follow this step in the setup
   
  "Measure between OG and SG. This should be very close to 12V. If it's not there might be a problem with the TLE2426 or with one of the devices in the rail splitter."  
   
  I had the negative lead of my volt meter on the SG pad and the positive lead on the OG pad and I was expecting this to be 12v but it was 1.3 VDC and SG to OL/OR was 0 VDC.
   
  You want me to measure the voltage before the relay. Below is the silkscreen with Red and blue dots to where I think you want me to take the reading from to SG.
   
  http://i11.photobucket.com/albums/a175/bnorton/CTHSilkScreen.jpg
   
  Also please let us know the heater readings (voltage bet pins #4 & #5) for both 6V & 12V heater switch positions.
   
  Is this with or without a tube in.  I am assuming without.
   
  Sorry for the rudimentary questions I just want to make sure I don't damage anything further and thanks for the tip about attaching pins to my probes.


----------



## cfcubed

>  I wrote all of this without seeing your second post.
   
  Yeah, my fault for not speaking to your 1st step / 12V vs 1.3V test fail.  The primary measurement/test right now is your 24V regulator/ICP readings. That can be done w/ or w/o tube. 
  If you get 24VDC out of it (its center pin -> *O*utput pin) again this may be a problem in the rail-splitter circuit (which is primarily responsible for making SG-OG read 12VDC).
   
  To speed things you could then carefully go ahead & do the high-voltage TB+ / SG and low-voltage heater (measure across tube socket pins #4 & #5) tube-in readings.
   
  And yep, those dots in your image are correct if we end up needing to do the true/pre-relay DC offset reading.  We'd do that only if/when we pass all the standard "setup" tests & still had a problem.
   
  Edit: Don't see a heatsink on ICP/24V reg in your pic, it must have one.  And please again check the proper opamps are in the proper sockets (there are singles & doubles) plus the transistor locations (it is color-coded though):
http://www.cavalliaudio.com/diy/cth/images/CTHPartTransistorLocations.jpg


----------



## blaken

Ok ICP center to IR = 0v  ICP center to OL didnt measure.  What I mean by that is when I measured IR my multi-meter read 0v but when I measure OL it kept bouncing around in the mv which is what it does when there is no continuity.
   
  TB-SG was 110v
   
"low-voltage heater (measure across tube socket pins #4 & #5)"
"Also please let us know the heater readings (voltage bet pins #4 & #5) for both 6V & 12V heater switch positions."
   
  Sorry I want to make sure I am clear on this before I do it.  Do you want me to measure (#4 to #5) or (SG-#4 and SG-#5).
   
" Don't see a heatsink on ICP/24V reg in your pic"   
   
   I took it off for the picture so everything around ICP would be easier to see.  I put it back on before I did any more testing.
   
"And please again check the proper opamps are in the proper sockets (there are singles & doubles) plus the transistor locations (it is color-coded though):"
   
  I went over every transistor and opamp and verified it is the right one in the right orientation.  My only question is Q1P.  The bom says it is a BC337 but the color chart here http://www.cavalliaudio.com/diy/cth/images/CTHPartTransistorLocations.jpg has it as a BC550.  I put in a BC337.
   
  Thanks again for your help.


----------



## cfcubed

If you are getting very low voltage readings for input & output on the 24v regulator (ICP) then the problem in probably in the GREEN box:


----------



## blaken

That diagram is perfect.  I will get those measurements taken.  Do you know what q1p is suppose to be?  The discrepancy between the bom and the color diagram has me concerned.  I will start checking the other parts in the green box.


----------



## cfcubed

Ack, forgot your Q1P query.  Yes,  BC337 is the proper Q1P sub for BC550 in your version of the CTH PCB.
   
  And if you've no 24V out of ICP then don't bother with the "75plus" measurements in the diagram (yet), and very close review/testing of parts & solder joints in the green boxes makes sense.  If nothing seems bad there then try to measure the "33+, 33-40VDC" points below WRT SG when powered.
   



blaken said:


> That diagram is perfect.  I will get those measurements taken.  Do you know what q1p is suppose to be?  The discrepancy between the bom and the color diagram has me concerned.  I will start checking the other parts in the green box.


----------



## blaken

IT LIVES!  Thanks so much for your help cfcubed.  To no ones surprise it was builder error.  C4P was backwards.  After switching it and then double checking every other cap on the board and going through all the setup tests again it fired up just fine.  My input leads are way too long and picking up a little noise but after situating those it sounds great.  I've been putting it through it's paces for the last couple of hours and I couldn't be happier.  I am going to grab an RK27 for it and one of amb's nifty ε27 boards.  
   
  One last question does SG really need grounded to the case since nothing else is?
   
  Up next, crossfeed, probably a corda cross.


----------



## cfcubed

>  C4P was backwards. .....   I've been putting it through it's paces for the last couple of hours and I couldn't be happier.
   
  Great news that you found/fixed the problem & are happy   Note though that polarized caps don't take kindly to having reverse power, they can explode (another reason to wear eye protection).  Lesser symptoms are case swelling or "poor" performance.  I'd replace a cap that's been reversed or had its voltage rating exceeded.
   
  >  One last question does SG really need grounded to the case since nothing else is?
   
  Yes, if its a metal case - grounds the case against noise (btw IG=SG).  And ground pots w/metal shafts too (if not ground through metal endplates, search RK27 ground screw).


----------



## blaken

Sorry Cfcubed but I am having another problem.  I went ahead and replaced C4P then cased up my CTH but now it just humming very loudly as in full volume loud.  I ordered a spare c4p so I tried a different cap since that was the only thing that changed but it didn't do any good.  I already threw away the original one but I doubt that's the problem.  During casing I rewired the power switch, output jack and pot. For the pot I used an amb ε27. The hum occurs with no input and the pot unplugged.  I have searched the board for any lead that could have got bent over but have found nothing.  It has been cleaned with alcohol.  The c4p from the original bom was unavailable so I got this one.
   
   http://www.mouser.com/Search/ProductDetail.aspx?R=UVR1H100MDD1TAvirtualkey64700000virtualkey647-UVR1H100MDD1TA
   
  I also tried different tubes and checked all the voltages.


----------



## cfcubed

My bet is that your hum after case up has nothing to do w/C4P, though I'd carefully review that section visually & w/DMM as you worked there.  The C4P replacement you linked to is fine.
   
  Thinking this may be a wiring issue, e.g. you must take care that IG does not contact OG.  Please review all wiring visually & v/DMM:
http://cavalliaudio.com/diy/cth/main.php?page=wiring
   
  Quote: 





blaken said:


> Sorry Cfcubed but I am having another problem.  I went ahead and replaced C4P then cased up my CTH but now it just humming very loudly as in full volume loud.  <snip>
> I also tried different tubes and checked all the voltages.


----------



## blaken

I just can't win with this amp lol.  I figured out what the problem was. The ε27 board has 4 pins for in and 4 pins for out.  The outer pins are L and R and the two center pins I assumed were ground.  On the board I have the G is centered between the two middle pins.  Well it turns out at least on my board only 1 of those pins is ground and the other is nothing.  So on the (in) of the pot it was grounded but there was no IG going out to the board. 
   
  So it's working again... sort of.  One channel is at full volume no matter where the pot is and the other is working as intended.  I checked the resistance from my input jack all the way through to the IR/IL pads they are fine.  I tried different tubes a 12v and a 6v with no change.  
   
  I should have just left well enough alone when I had it working and just leave out the blue velvet and everything would be fine but It seems like I might have really screwed something up this time.  The only saving grace is I could just leave it running at full volume all the time and use my input device to control the volume.  The only thing I can think of is I zapped something when I was trying to trouble shoot the other problem.
   
  Any help would be appreciated.


----------



## cfcubed

>  One channel is at full volume no matter where the pot is and the other is working as intended.  I checked the resistance from my input jack all the way through to the IR/IL pads they are fine.
   
  This can only be external to the CTH PCB, it is a problem between your input jack & the IG/IR/IL pads.  When you check the resistance are you also checking that your pot is sweeping the CTH inputs to ground?
  IOW, input attenuation consists of sweeping the amp's inputs (IR&IL) from ground (IG/input gnd) when @ zero volume to the input jacks L&R when @ full volume.
  Don't give up
   
  >  I should have just left well enough alone
   
  I'd vote for that as DIY's mantra   We all get bit by this one time or another, runeight even made that his sig


----------



## blaken

After reading your comment I had one of those head slapping DUH! moments.  The  ε27 board was made for balanced input so the L/R grounds don't connect.  One of my channels was properly grounded and the other was not sweeping to ground.  So after making a little jumper that problem is solved.  I just need to get it cased back up and possible adjust the gain a bit but I used sockets on the gain resistors so that will be easy.  I was thinking of not leaving well enough alone and replacing my input cabling with shielded cable.  I have some canare star quad somewhere.  I just can't stop myself.
   
  Thanks again for all your help.


----------



## jdkJake

Quote: 





blaken said:


> After reading your comment I had one of those head slapping DUH! moments.  The  ε27 board was made for balanced input so the L/R grounds don't connect.  One of my channels was properly grounded and the other was not sweeping to ground.  So after making a little jumper that problem is solved.


 


  ????
   
  The e27 is designed for single-ended input, not balanced. In fact, the e27 uses a common ground plane for all inputs and outputs. So, I am most curious what you actually jumpered to solve the problem.
   
  You should at least consider attaching the ground leads of both input sources as well as running at least one of the output grounds to both channel input grounds of the amp.


----------



## blaken

When measuring my board the 3 marked points I thought were ground did not have continuity to the ground plane.
   
   

   
  The board I have is a newer revision than this one.  There are also two more ground points on the one I have which was nice for grounding the pot itself.  I jumpered the two inner ground pins on each side and jumpered G+ to GI.


----------



## truto

Hello, I'm finishing the build of my CTH i started one year and half ago, its all populated and wired but I'm getting some troubles.
  When doing the first measures OK, but with a tube the e12 switch green and immediately return to red.
   
  This are my measures without any tube inserted:
   
  All Output > SG = 11.8v
   
  1 > SG =110v
  4 > 5 = 35.8v @  heater 6v
  4 > 5 = 36.1v @ heater 12v
  SG > TB+ = 111.9v
  ICP 34.8V and 23.7v 
   
  Can i get some help solving this guys? Thanks


----------



## cfcubed

Could you please see the CTH debug link in my sig & my debugging posts and reply with the results? Also hires bottom and top PCB photos could help.


----------



## arteom

Hi guys. I have been having some issue with my CTH, its the original board, not rev a. When I power it up, R16R starts smoking, I did replace that, and also replaced Q8R (just because it was near and I had a spare), but problem persists. Any idea what can be causing this? Thanks in advance for any tips troubleshooting this.


----------



## Shini44

Hey guys is there any Hybrid amp for  CIEMs that give me warm lush mids/vocal and fun extended Treble which is fun? also fun bass if possible

 i had WA7 with EH Tubes, was't this fun :<  Super mids i know but the Treble and Bass were tube level though that the EH tubes were the best option for that
  
 desktop amp if possible else i will go with the current options :/ 
  
  
 PS: i am a Treble head and i don't mind a punchy bass that isn't in the way of my forward/sweet/lush/transparent mids


----------



## HeadphoneAddict

shini44 said:


> Hey guys is there any Hybrid amp for  CIEMs that give me warm lush mids/vocal and fun extended Treble which is fun? also fun bass if possible
> 
> i had WA7 with EH Tubes, was't this fun :<  Super mids i know but the Treble and Bass were tube level though that the EH tubes were the best option for that
> 
> ...


 

 If I recall, my HiFiMan EF2 hybrid amp with Raytheon 6AK5 tubes was good with my IEM, but you might want to search for my review to confirm that.  It's not super powerful with todays orthodynamics, but it's good with Grados and HD800 alike.  This is of course using it as just an amp, with an upgraded DAC.


----------



## Mullet

I'd have to say the CTH unfortunately wouldn't be a good choice for CIEMs. There is a slight 60hz buzz with this amp that is for some reason inherent in the design. It's not bad at all with 95% of the headphones I use. You notice it with IEMs because of their high sensitivity.


----------



## Tribbs

Need help to troubleshoot a problem while performing an initial start up smoke test.

*Plug in the wallwart and wait for at least 2 minutes. If there is smoke turn of the amp immediately, but if not wait.*

 Had to replace C1P. It was reversed :rolleyes: It bulged but did not short. (Measured 1.3MΩ after removal.)

*The indicator should go from red to green.*

 Remains red.

*Whether it does or doesn't, check these voltages anyway.*

*•Measure between OG and SG. This should be very close to 12V..*

 I'm getting 23.1V here. - What should I be checking next to isolate the problem?

I wonder if IC1 (TL082CN) was damaged when C1P popped?


----------



## cfcubed

Could you also please take a look at CTH debugging link in my sig & respond to anything else it might query?:
http://www.head-fi.org/t/398839/a-very-compact-hybrid-amp/2175#post_7837361
  
 When something goes wrong on this small of a board, with this many parts, it can be difficult & painful to diagnose.
 Wouldn't hurt to re-check (all?) other parts, orientation & soldering.  
 C1P is part of the LV supply that feeds the "main" portions of CTH, e.g. the input / output / rail splitter stages - most all the ICs & other "sand" (TO92s).  That stuff is more tricky to diagnose & repair than the heater & HV sections.


----------



## Tribbs

I just cleaned the flux so will wait until tomorrow to let it dry and take measurements.

Meanwhile, I'll get this out of the way...
The two pairs of yellow wires are temporary for the heater rotary switch and PS fuse.
The OpAmps have been temporarily removed. Verified orientation of all relevant components multiple times.

Looked over all joints with magnifier several times.


----------



## cfcubed

tribbs said:


> *•Measure between OG and SG. This should be very close to 12V..*
> 
> I'm getting 23.1V here. - What should I be checking next to isolate the problem?
> 
> I wonder if IC1 (TL082CN) was damaged when C1P popped?


 
  
 Others may know better but I'd focus on rail splitter then output buffer sections - see CA DIY orig CTH site.  Swapping out the chips in those sections with known-good ones could be the easy/happy path but wouldn't be surprised if you'll have to go after TO-92s as well (RS then OB).  TLE2426 would be the first I'd pull & swap. 
  
 But as one with little patience for tedious sequential replacement myself, and given the possibility of new parts being damaged by state of other damaged ones, I went shotgun on those sections the time I had a problem there myself.   IOW if ordering parts I'd order all sand in RS & OB sections and be prepared to replace.


----------



## Tribbs

cfcubed said:


> Others may know better but I'd focus on rail splitter then output buffer sections - see CA DIY orig CTH site.  Swapping out the chips in those sections with known-good ones could be the easy/happy path but wouldn't be surprised if you'll have to go after TO-92s as well (RS then OB).  TLE2426 would be the first I'd pull & swap.
> 
> But as one with little patience for tedious sequential replacement myself, and given the possibility of new parts being damaged by state of other damaged ones, I went shotgun on those sections the time I had a problem there myself.   IOW if ordering parts I'd order all sand in RS & OB sections and be prepared to replace.




This is interesting...

With all five OpAmps (ICE, ICL, ICR, IC1S {TL081} & IC1 {TL082}) removed I applied power.
After about 10 secs I heard the relay click and the LED went red to green.
Now OG to SG = 12.5V (Yay?)

Output of the ICP voltage regulator = 24.1V

New OpAmps and TO-92's were ordered yesterday.

FYI - The TL082CN in DIP packages are getting scarce. Production has ceased.
The main suppliers (Mouser) only have them in a SO-8 (SMT) package (TL082CDT). An adapter would be in order if pressed.
However, sellers on eBay and Amazon are still stocked.


----------



## cfcubed

tribbs said:


> FYI - The TL082CN in DIP packages are getting scarce. Production has ceased.
> The main suppliers (Mouser) only have them in a SO-8 (SMT) package (TL082CDT). An adapter would be in order if pressed.
> However, sellers on eBay and Amazon are still stocked.


 
 AFAIK there's nothing special about the TL081s & TL082s as used in CTH circuits & they don't lie in the (direct) audio signal path, e.g. TI & other makers of that spec would be fine.  Think BB OPA134s & OPA2134s are also good if pricier substitutes (IIRC they are what I happened to use in CTH's 1st breadboard proto).    Otherwise sticking with (J)FET input stage opamps, with same/"standard" pin-out, and comparable datasheets should ID others.
  
 BTW *if* RS keeps any stores open or maintains website sales (& follows through with such sales, they appear to have TL082s: http://www.radioshack.com/tl082-tl082cp-wide-dual-jfet-input-op-amp-8-pin-dip/2761715.html#.VQnIuGaJKHk


----------



## arteom (Feb 5, 2018)

The cth was on my mess of a work-table for 4 damn years. The story is that I had decided to rewire the amp using nicer wire and to install a TKD stereo pot. The wiring went mostly well, I say mostly because the round metal ring came off where you would connect the input ground. After installing the new volume pot, and wiring the same as the rk27 before it (or so I remember), the damn thing started picking up Spanish radio.. had me scratching my head. Anyway, at that point I also had a EHHA so I left it on my bench. I got back to it a few times in the years since, trying different wiring schemes, no luck.

Had some days off recently, so gave it another go. Wired in the old pot, it worked! Not wanting to be beat by the TKD, I tried to connect it, first using jumpers to test. Seemed to be working, some hum. The TKD is about twice the size of the Alps rk27, so had to take care wiring and mounting it. Did that, reflowed IG.

The little beast is alive! Sounding better than I remember. A few extra holes on the front, and the screws that I didn't lose aren't doing all too great of a job holding the front and back panels on the hammond case, will need to get creative to fix that. But should be doable.

I should also mention previous to all this I had blown some transistors on it while tinkering with it, had gone through and replaced them all. A few caps swapped as well. I'm surprised it's held up.

Feel quite a bit of nostalgia listening to it. This thing is a keeper, will be holding its residency in my office, along with a Headroom Micro DAC. A shout-out to @runeight , you're a goddamn legend!


----------



## arteom

well, spoke too soon, the wire connecting to IG on board broke off. I don't think I will be able to connect IG to the board anymore, it's stripped, and pretty much done. Looking at the board, it looks like IG (input ground) is isolated from rest of the board. Can I put in a piece of metal on something like a nylon stand-off and use that as IG? Any other ideas of how I can work-around this?


----------



## cfcubed (Feb 7, 2018)

IG is input ground.  You can tag IG wire along with any nearby component's connection to ground (PCB top layer).  E.g. R1L resistor's lead/pad right next to IG pad, or nearby R1R lead.  You can see their pad connections to PCB top-plane/ground and use ohmmeter to confirm.  Note also that IG=SG.


----------



## arteom

cfcubed said:


> IG is input ground.  You can tag IG wire along with any nearby component's connection to ground (PCB top layer).  E.g. R1L resistor's lead/pad right next to IG pad, or nearby R1R lead.  You can see their pad connections to PCB top-plane/ground and use ohmmeter to confirm.  Note also that IG=SG.



Wired it to same spot I had SG connected. Worked out well, least messy. Thanks for the tip!!


----------



## wolfield

Does anybody have the schematics still laying around? Would someone be kind enough to share?


----------

