# EHHA Rev A - Interest Thread



## runeight

There has been some interest lately in the EHHA Rev A amp. As many of the know the original EHHA is available from Glass Jar Audio and information about it it on the Cavalli Audio website.
   
  Rev A is designed to simplify the build while improving the amp.
   
  Things that are the same in the two amps:
   
  1. Still uses 6GM8s
  2. Sill runs the tubes from the 30V rails.
  3. Still has mosfet or bjt outputs
  4. Can still be configured for ranges of OL and CL gains (or equivalently NFB)
  5. Still runs at 100mA bias with plenty of power
  6. Is still DC coupled front to back. No coupling caps
   
  Things that are different:
   
  1. Diff amp CCS is now a CRD for simplicity
  2. Each board has built-in, linear regulated rails. That is, each board is a complete amp.
  3. All you need are one 30-0-30/400mA transformer and one 6.3V/1A transformer (or a DC heater supply)
  4. Sigma22 is not required in this version
  5. No more trimpot on the diff amp
  6. EF drivers for the O/P stage increase bandwidth
   
  One prototype has been built. The amp works very well, but it has not, so far, been tested over multiple builds by different people. Please remember this sentence as the discussion proceeds.
   
  I can post a schematic if you all are interested in going further and even the current board design.


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## ujamerstand

Sounds like good news! I'm all in for new revisions, I've got most of the parts needed to build the original EHHA already.


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## nullstring

has anyone compared this and original amp?
   
  My ignorant opinion would seem to think that a sigma22 would supply cleaner power, and an external PSU would cause less noise.


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## runeight

No, no comparison has been made, but this is a very fair question. MHO is that there will be little difference, but only a real world comparison can say for sure. The gentleman who has the Rev A proto does not have an original EHHA.


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## dasein-geist

Will this new revision still be able to be configured to run speakers as well as headphones?
   
  Certainly, the transformer specified seems a little light for speaker duty...


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## runeight

No, this is not a speaker amp as was the EHHA.
   
  The regs are standard 1A regs so you can certainly beef up the output, but you won't be able to pull the >2A needed to get 20W into 4R.
   
  If you guys really want the speaker amp too then the board would have to be redesigned for this mode of operation.
   
  One of the limitations on the current EHHA is the need for a separate PS. This has both advantages and disadvantages. The idea here is to make it possible to build the amp without the additional complexity of another supply.


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## jdkJake

Sounds interesting to me.

 I think at least posting the schematic would be kind to say the least. That way we can see and discuss the relative merits of the upgrade. Probably discuss it to death! 

 A very kind offer, which, I don't think this forum should pass up.


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## dasein-geist

Quote: 





runeight said:


> No, this is not a speaker amp as was the EHHA.
> 
> The regs are standard 1A regs so you can certainly beef up the output, but you won't be able to pull the >2A needed to get 20W into 4R.
> 
> ...


 

 While I _am_ interested in the Rev. A, it seems like it would be a whole lot of extra work to (re)configure it for speaker duty; thus, it seems like I'd be better off sticking with the current design - unless, of course, the consensus of others is a redesign would be worthwhile.
   
  In any case, thank you, again, Dr. Cavalli, for your continued efforts for the DIY community. Your continued support is much appreciated...


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## Beefy

I'd love to see a board design and schematic, just to see what sort of casework would be required......


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## runeight

Here's a schematic.


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## runeight

As for redesign, it will be very easy to strip off the PS section. But then you all have to build a s22 to make a complete amp. Or any bipolar 30V supply.


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## FallenAngel

Nice idea, looking very good.  I'm really tempted to get a few boards and build in a few months when I can build again.


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## dasein-geist

Dr. Cavalli,
   
  (respond: board redesign)
   
  I do like the streamlining/symmetry of this revision (e.g. obviating the differential amplifier circuitry)...
   
  However, it seems that the majority of this revision is centered around integrating the power supply.
   
  Now, don't get me wrong, this is a *fantastic* revision (it significantly reduces the complexity and clutter of the build - and not incidentally, I would assume cost).
   
  For these reasons, *I personally* would _not_ want to be the reason for stripping the power supply from this revision. I think the potential space/ease of build/cost benefits are too great - even if that means the original EHHA design would would best for _my_ purposes.


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## runeight

Thanks, but it's really ok with me whatever you all want to do. The main thing will be to have enough interest. And if there isn't that, that's ok too. There is plenty to do right now trying to get the commercial amps going.


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## jamesbobo007

My next build will be a EHHA so I'm very interested.


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## stringgz301

I'm in for a board.


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## qusp

hmm after more thought; I think perhaps the original boards are more suitable for me; I already have an abundance of high quality regulated supplies (including a spare sigma22) and I like the option for using it for bookshelves at some point. i'll keep an eye on this thread for more details and thanks for offering this, but i'm not sure it would be wise and would actually in my case cost me *more* in money and time, as the supply already exists (just need to change the output voltage)


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## ujamerstand

I prefer to keep the on board power supply section. This should save me precious space in the chassis. However, if there is an option for us to bypass the onboard PS, it would allow us to make comparisons between the on board supply and other power supplies. (I've also got a sigma22 lying around)


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## MrSlim

Perhaps the board could have could have the Amp and Power supply sections separated, and joined with jumpers if the local PS was used, and it would be a convenient connection point for an external power supply.  It would also be useful for anyone interested in experimenting with something like the JLH ripple eaters. 
  That way a single board could be provided, going forward. 
   
  Will the new rev board use the 6GM8 exclusively (no more 6922/6DJ8) ?  
   
  Is there a reduction in sound quality in any way on the current EHHA with the 6922/6DJ8?


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## tcpoint

I'd be interested in a board.


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## runeight

Gents, here's one possibility. It's a single board that includes the on-board PS. However, it has a cut line that can be scored by the fab. You'll be able to snap off the PS section and connect your external rails to the interior terminal block which will now be close to the edge of the board.
   
  There are two sets of mounting holes in the back so that when you cut off the back section you'll still have mounting holes.
   
  You can see the cut line right above the green via in the center back of the board.
   
  Do this suit everyone's needs?


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## jdkJake

Works for me. 
   
  Personally, I like having the option of the onboard power supply. Even a simple trace cut would have sufficed. This is just icing on that cake.
   
  What is the size of the proposed board? Looks to be nice and manageable for lot's of casing options.


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## ujamerstand

Could we substitute the bipolar power supply with a lt1084 or lm338 based dual supply for higher current output? Or would a dual supply be unsuitable for the EHHA? 
   
   
   
  Quote: 





>


 


> What is the size of the proposed board? Looks to be nice and manageable for lot's of casing options.


 
   
  I measured it, its about 11cm x 13cm, small enough to fit 4 in a 12 x 12 case without the transformer.


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## runeight

Yes. The standard headphone amp would use LM317/337, but you could sub the 5A LM138/338 directly without any other changes.
   
  It might be possible for me to give you mulitple filter cap sizes so you can increase the filter caps for high current use. The standard headphone amp size is 2200u. For speaker duty, bigger caps would be helpful but not absolutely necessary.
   
  The board is 110mm x 130mm with PS and 110mm x 85mm with the PS section snapped off.


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## runeight

No. Not a direct sub because the pinouts are different on the negative regulators. As best I can tell.


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## runeight

Even more no. Responding without thinking.
   
  Is there a 5A negative adjustable regulator?


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## ujamerstand

None that I know of, but I could be wrong. I was hoping a dual supply supply would work?


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## bada bing

Looks like another great project.
   
  I'll commit for 4 boards if this gets a board run made. I can't commit to getting it built in a hurry though, if that's an issue. Probably build next spring for me, as I already have an operating EHHA and several unbuilt projects I'm looking forward to.
   
  Nothing has changed on the output buffers from the original? FET or BJT output options still work, yes? I have FETs on my EHHA and would like to hear what the BJT would sound like if I built another variant. 
   
  A comment about the board layout. On any amp project that dissipates much heat/power, I have a personal preference for a board layout that puts the output devices on one end of the board to facilitate offboard heatsink options. It allows for a shallower case height, better heat management and looks "cooler" to have external case fins. I really like how the original EHHA board was set up this way. I know tradeoffs have to be made for other reasons though.


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## qusp

nah a dual wont work without some sort of modification.
   
  well this just became more interesting again, put me down as interested and yes several size patterns for caps is a great idea, if possible with some small amount of space for critical ones, so film caps can be used (non-essential, but would be cool) if possible, can you add intermittent (not plated through) holes for the in between pins so 2.5mm molex or similar can be used with 5mm grid? twisted pear does this and it works well. of course the middle pins can just be removed, but makes it easier having the holes there.


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## ujamerstand

I did some checks and found that a four board configuration would have a larger footprint than a balanced original EHHA + s22 setup. So molex pins on the boards would be nice; we could snap off the ps on two boards and power them with the other two boards. 
   
  Quote:


qusp said:


> nah a dual wont work without some sort of modification.


 
That's true.... Edit: Actually I'm not so sure about this, dbel mentioned a dual supply as a possible PS for the EHHA at the old headwize thread... From my understanding it should work, but I'm wrong a lot of the time... Anyways, I would like to take 4 boards as well.


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## qusp

hehe, yeah but I dont know how trivial it would be. so yep, put me down for 4 boards


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## runeight

This is a really interesting discussion. I'm glad we're having it.
   
  Along with circuit tweaks, the primary idea here was to relieve you of the external PS complexity. This change was aimed primarily at SE (non-balanced) amps. Make the build easier and have separate PSs on each board to reduce crosstalk through the PS.
   
  But, the snap-off version does increase board size by 10mm in length. making built-in PS version a little less compact and useful for its original purpose and even more challenging for a balanced amp.
   
  Before we fix on the latest there is another alternative still.
   
  I could simply redo the original EHHA board with the circuit tweaks. The only thing that would change would be to reduce the number of heatsink locations from four to two.
   
  Then we could figure out a PS arrangment for those who don't want the s22.


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## fishski13

Quote: 





runeight said:


> This is a really interesting discussion. I'm glad we're having it.
> 
> Along with circuit tweaks, the primary idea here was to relieve you of the external PS complexity. This change was aimed primarily at SE (non-balanced) amps. Make the build easier and have separate PSs on each board to reduce crosstalk through the PS.
> 
> ...


 

 this is an amp i want to build.  i already have a s22 powering my B22, but would like to have the option of populating the on board PS or using my s22.  count me in for a stereo pair.


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## Beefy

Quote: 





> Originally Posted by *runeight* /img/forum/go_quote.gif
> 
> I could simply redo the original EHHA board with the circuit tweaks. The only thing that would change would be to reduce the number of heatsink locations from four to two.
> 
> Then we could figure out a PS arrangment for those who don't want the s22.


 


 That sounds like a much better idea. I don't think that there is any particular benefit to having the PSU on the same board...... but a separate board for a specific power supply simpler than the S22 might be handy for some.
   
  Still, I suspect most will opt for the S22 anyway......


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## Forte

Quote: 





runeight said:


> Along with circuit tweaks, the primary idea here was to relieve you of the external PS complexity. This change was aimed primarily at SE (non-balanced) amps. Make the build easier and have separate PSs on each board to reduce crosstalk through the PS.


 
   
  I like the idea of a simple build, complicated isn't always better. 
  Keep the on board PS with the option to use an external supply for those who want to go all out.
   
  Can the new design still use 6922/6DJ8 & 6H30 tubes? 
  I thought I saw an answer to this but re-reading this thread cannot find it now.


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## pabbi1

I know this is a bit afield, but would this amp benefit from adding adding DC heaters, or is that a complexity that may not add real benefit?


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## jdkJake

runeight said:


> This is a really interesting discussion. I'm glad we're having it.
> 
> 
> 
> ...







 So, I guess I liked the idea of the built-in power supply. I would even forgo the snap option to get the board back to being as small an implementation as practical. Of course, I am looking to build a SE version and not a balanced version.

 Are the remaining circuit tweaks enough to justify a respin of the original EHHA? To me, the attractive part is a smaller, simpler implementation that does not require an additional power product. Otherwise, is the original EHHA that far off from the new design?

 Then there is still the big unanswered question, will the new version sound any better?


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## runeight

New design can still use 6922/6h30 although these might be less optimal.
   
  DC heaters are ok and might reduce noise.
   
  Will it sound better? I don't know. I know it will be faster, but this difference will be at fairly high frequencies.
   
  Seems like we have different thoughts about on-board or off-board PS and whether to just tweak the orignal EHHA board or use the new one.
   
  I guess we need to think on this further.


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## jdkJake

I'm flexible. Anyway you want to do it is fine by me.

 There are distinct advantages to a separate power supply as well advantages to the current boards ability to use external heat sinks, so, that works as well.

 Whatever the consensus is works for me.


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## tcpoint

I, actually, prefer having the power supply on the board.  This looks like a fun build.


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## fishski13

i haven't built the original, but what are the issues here?:
   
  -you want to use the boards to drive HPs with or without the newly added on-board PS (me).
  -you want to use the boards to drive speakers, but will need to use an off-board PS (s22 or other home-brewed regulated or unregulated).
   
  seems like it's easily rectified with a scored PS/Amp board PCB.  the new PCB has the new PS on one scored portion and the Amp on the other with pads on both sections to solder in the PS.
   
  Alex,
  what JFETs/resistors are the CDRs replacing?  is this just to simplify to CCS - do the JFETs  need to be matched?  and while CDRs are more expensive, they offer a simple design approach, like zeners?  can i have PCB pads for CDR, CCS, and a dumb resistor 
	

	
	
		
		

		
		
	


	




.


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## runeight

Next step. Trying to meet all the needs. 
	

	
	
		
		

		
		
	


	



   
  This is the same split board as before with some mods. I've left the bottom layer power planes visible so you can see how they traverse the board. Click the pdf and you can get the full sized image.
   
  First, the PS section has an additional set of mounting holes. It has two connectors on it now so it can stand alone. If you split this off you can use it to make a separate, stand-alone regulated supply for other purposes provided that you don't exceed the power dissipation in the heatsinks.
   
  If you leave the PS section connected it will automatically power the amp board through the power planes on the bottom and ground plane on the top. In this case you don't use the terminal blocks in the middle of the board except to take the O/P. But, you can also use the terminal block on the PS section to run wires to another board that doesn't have the PS section.
   
  Or, you can split off all of the PS sections and use a different supply.
   
  The only thing not done is to get the O/P devices to a convenient location for off-board heatsinks. To do this will substantially increase the size of the board and maybe make it impractical.
   
  However, what I can do is to ensure the the mosfets are oriented in such a way so that they can be laid flat on heatsinks that would be on either side of the board. I haven't done this yet, but if you all like the rest of the board I can make this change.
   
  The bjts will not be oriented correctly for this, but the fets will.
   
  fishski, the CRD is replacing Q3, R8, R9, D1, D2. R6 has also been removed, but was not part of the CCS. I think I will leave it alone. You can always put a resistor there if you want, but adding a bjt ccs will be more complicated.
   
  There are no jfets in this amp so no jfet matching is required. For the 2SC2705/2SA1145 it is best to buy them in the same gain classes, but no further matching should be needed.
   
  Are we getting closer?


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## runeight

Board might look something like this


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## fishski13

i understand the CCS now after spending some time looking over the schematic.
   
  well you could do off-board heatsinks as is if the output devices are mounted underneath.  are those C9 and C12 electrolytics near the output devices?  at less than 0.5" tall, you could bottom mount these and use 0.5" stand-offs to allow top-side mounting of the output devices for off-board heatsinks with an L-bracket.


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## stixx

Nice, compact looking board...
  I am still in for a stereo pair, but give it some time until you make it a Group Buy 
  (vacation until Sep 11)


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## jdkJake

Quote: 





runeight said:


> Are we getting closer?


 

 Works for me. I'm in.


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## runeight

Quote: 





stixx said:


> Nice, compact looking board...
> I am still in for a stereo pair, but give it some time until you make it a Group Buy
> (vacation until Sep 11)


 


 OK. I need to talk further with Jeff Rossel anyway so we can wait a bit. I would prefer for kits to be available along with boards, but as many of you know, Jeff has been very busy.
   
  This latest version simply has the mosfets in the right orientation and matches the 3D above.
   
  There is one question I'll have to ask the fab. When you snap the PS section at the score line you'll also be snapping it through the bottom layer copper power planes. We need to know if the copper will separate nicely.


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## Lil' Knight

Looks great. I'm in for a balanced set.


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## Sathimas

Ah - you're tempting me !
   
  How much would it (just approximately) cost to build one amp?
  (2ch, only parts - no case included)


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## sachu

Am thinking if you use the on board supply you are looking at about 200$. Biggest bang for buck ever if you ask me if it sounds anything like the EHHA-1, though this one is supposedly faster too.


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## fishski13

Quote: 





sachu said:


> Am thinking if you use the on board supply you are looking at about 200$. Biggest bang for buck ever if you ask me if it sounds anything like the EHHA-1, though this one is supposedly faster too.


 

 i was thinking the same thing.  the o22 adds a significant cost.


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## sachu

Indeed..the S22 would add almost another 70$. To be honest, I would just go with the onboard  PSU, though am curious to see any measurable differences translates to discernible differences in sound quality using the two different PSUs.


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## fishski13

Quote: 





sachu said:


> Indeed..the S22 would add almost another 70$. To be honest, I would just go with the onboard  PSU, though am curious to see any measurable differences translates to discernible differences in sound quality using the two different PSUs.


 

 i have a friend that wants me to build him a SOHAII.  this EHHA revision would probably come in a little cheaper, but would need to factor in an e12.


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## Beefy

Quote: 





fishski13 said:


> i have a friend that wants me to build him a SOHAII.  this EHHA revision would probably come in a little cheaper, but would need to factor in an e12.


 


 Why would you need an e12 in an amp with a DC nulling servo? Surely it isn't that slow......


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## johnwmclean

Yeah, that’s what I was thinking.


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## fishski13

good question.  i guess i wasn't really thinking why i would need it 
	

	
	
		
		

		
			





.   i just assumed it was an added as a fail-safe device for DC coupled amps.  but doesn't the SOHA II have a DC servo on the outputs as well and uses an e12?  why is this?


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## Beefy

Quote: 





fishski13 said:


> good question.  i guess i wasn't really thinking why i would need it
> 
> 
> 
> ...


 
   
  "Notice that R1E and R2E are changed from 10kΩ to 33kΩ and that R4E is changed from 1kΩ to 2kΩ. The purpose of these changes is to make the SOHA II ε12 less sensitive and a bit slower. This is because the SOHA II SE Buffer can generate a bit more offset under certain signal conditions before settling down. However, the SOHA II ε12 is still sensitive enough to prevent damage to headphones."
   
  http://www.cavalliaudio.com/soha%20ii/main.php?page=schematics/e12schematic
   
  So the SOHA II is a special case, because its buffer drifts around a bit. I have to assume that Alex leaving it out means the EHHA is more stable.


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## cobaltmute

Quote: 





runeight said:


> There is one question I'll have to ask the fab. When you snap the PS section at the score line you'll also be snapping it through the bottom layer copper power planes. We need to know if the copper will separate nicely.


 
   
  You won't be able to score the board - otherwise you'll cut the traces.
   
  How is the ground handled for a SE setup?  Where is the common point for the star grounding?
   
  A part of me really wants to build this.  The other part is looking at the stuff on my bench going I need to finish that first.


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## runeight

Thanks cobaltmute. As it turns out the score line and traces are placed such that the score line will not cut any traces. It will not even cut the ground plane on the top. And, when separating the PS, we do want to cut the two power planes on the bottom. My question for the fab will be if the score line is on the top will the power planes on the bottom separate nicely or not when the board is snapped? It could be that they won't, in which case we'll have to find another option.
   
  The ground point for SE setup with the internal PS is the mounting hole in the back-middle of the board between the PS section and the amp. Grounding here minimizes PS noise getting into the ground plane of the amp section. In fact, will effectively elminate it.
   
  Gents, the only reason the e12 is not part of the original EHHA is because it wasn't around then. The EHHA I does generate some power up transient, especially if the tube heaters are turned on at the same time as the rails so that the tubes are not conducting when rails are applied to the sand. I don't remember how much though.
   
  If I were to make a two channel, fully integrated EHHA similar to the SOHA II I would definitely build in an e12 just to be absolutely safe. But, we may not need to do that here.
   
  I haven't asked the Rev A proto builder about the transients. But I'll do that so that we have some data.


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## fishski13

thanks Alex and Beefy.
   
  i'd like to add another stereo pair.  4 boards total for me.


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## cobaltmute

Quote: 





> Originally Posted by *runeight* /img/forum/go_quote.gif
> 
> The ground point for SE setup with the internal PS is the mounting hole in the back-middle of the board between the PS section and the amp. Grounding here minimizes PS noise getting into the ground plane of the amp section. In fact, will effectively elminate it.


 
   
  But how about tying the two boards together?  I'm (over)thinking ahead to when you have two boards and two power supplies, with two ground points and then where do you tie the ground for volume and output ground. 
   
  Quote: 





> If I were to make a two channel, fully integrated EHHA similar to the SOHA II I would definitely build in an e12 just to be absolutely safe. But, we may not need to do that here.


 

 A two channel board with integrated power/heater supply would rock for building.  And then two boards would equal a fully balanced rig.
   
  Maybe it would be dreaming, but then having the two channel board fit into a 1455T2201 for total ease of casework...


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## runeight

LOL. You guys are merciless. 
	

	
	
		
		

		
			




   
  The measured DC offset swing on power up.down with cold tube heaters turned on with rails is a little over 1VDC. This is not so bad and if consistent across all builds might make an e12 unecessary. Although you'd have to think about 32R headphones some.
   
  With two boards each with their own PS, then you use the ground posts in the middle as the star ground point, either by putting a standoff and screw through this point to the chassis or by using the ground terminal on the PS output block to wire to the star ground.
   
  The input ground wiring goes to the IG terminal on the input block. Headphone ground goes directly to the star ground point on the chassis.


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## runeight

cobaltmute, you were right about the score line. It would have to be both on the top and bottom of the board in order for the board to snap correctly. I thought just the top would do.
   
  But, if it's on the bottom too then it will cut the power planes.
   
  Thinking on another solution. The easiest would be for you to wire across the terminal blocks for the on board PS.


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## runeight

double post


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## fishski13

Quote: 





runeight said:


> cobaltmute, you were right about the score line. It would have to be both on the top and bottom of the board in order for the board to snap correctly. I thought just the top would do.
> 
> But, if it's on the bottom too then it will cut the power planes.
> 
> Thinking on another solution. The easiest would be for you to wire across the terminal blocks for the on board PS.


 

 what are the actual dimensions of the board with and without a PS?  how about just leaving the PS intact with the amp portion and the builder has the choice to populate it or not?  i'm assuming making the PS separate would up the fab costs?


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## cobaltmute

What about a series of holes that makes it easier to cut the board into two?  It will affect the groundplane somewhat, but it should not be so bad.
   
  But then again, jumpering across the cut-line is also a very effective solution.


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## runeight

Making the PS separate would be very easy. That is, I would separate the power planes on the bottom so that the score lines don't cross an traces and you would connect the two board by wiring across the terminal blocks. The PS and amp would still be on the same board and this would be the same cost as paneling up mulitple boards onto a single board to get cost savings.
   
  I'm going to think about crossing the cut line, but I think the answer is going to be wires.


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## nullstring

I am considering building an EHHA very soon.
   
  When do you think this revision will be ready?
   
  I kind of want an external power supply for some reason.
  I am not sure, but the external power supply seems more versatile and can be used in more situations.
  But, I've never had one, so maybe I'm wrong.
   
   
  Is there any advantage to building an EHHA Rev A vs the previous EHHA version in the case that either versions would be using a sigma22?
   
  Thanks


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## fishski13

Quote: 





runeight said:


> I'm going to think about crossing the cut line, but I think the answer is going to be wires.


 

 sounds like a win.


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## runeight

Quote: 





nullstring said:


> I am considering building an EHHA very soon.
> 
> When do you think this revision will be ready?
> 
> ...


 

 The Rev A EHHA is just a little bit faster. The main change was putting a PS on the board so you don't need a separate external PS. If you are planning to use an external PS with either amp I would say there isn't a huge benefit to waiting.
   
  I'm going to wait for a bit more discussion and some folks to get back from vacation and for further conversations with Jeff Rossel before we decide when to make the new version available. So, I don't know yet.


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## dasein-geist

Alex,
   
  I'm not sure if you mentioned this before, but, do you know if on the prototype for Rev A. that has already been built, if the builder is running AC or DC heaters, and if he/she is running a separate transformer for the heaters or is running them off additional secondary windings?
   
  Pabbi1 already mentioned DC heaters in this thread, but I'm not sure it was really addressed.
  It seems like most of the EHHA-1 builders have been running DC heaters (with a separate transformer) - I believe Smeggy has this only EHHA that I know of that is running AC heaters).
   
  Since the power-supply is being completely redesigned anyway, it might be beneficial to discuss the separate heater supply options?
   
  What are everyone's preferences?


----------



## stixx

double post


----------



## stixx

I'd prefer DC heaters (regulated) in an amp of this level...parts count is low and not much real estate needed... just the transformer or a suitable secondary (when going custom).


----------



## tcpoint

I'd prefer dc for the heater voltage, as well.


----------



## sachu

yes, with this amp especialy please onlyy use DC heaters..There is an appreciable improvement overall in doing so.


----------



## runeight

Yes, although it is not absolutely necessary, it seems like nearly everyone gets better results with DC heaters on the EHHA. The gentleman who built the Rev A proto had the same result too.


----------



## jdkJake

Integrated DC heater power supplies. 
   
  Man, this thing may never get off the ground.


----------



## ujamerstand

Next thing you know people will want all in one stereo config with integrated DC heater supply. >.>
   
  Anyways, I like the current board, and I don't mind running a few wires over the score line. But if the board could be in red and yellow to match the millett filament supply it would be even better!


----------



## cobaltmute

Quote: 





			
				ujamerstand said:
			
		

> Next thing you know people will want all in one stereo config with integrated DC heater supply. >.>


 
   
  Quoting myself of a few posts back:
  
  Quote: 





cobaltmute said:


> A two channel board with integrated power/heater supply would rock for building.  And then two boards would equal a fully balanced rig.
> 
> Maybe it would be dreaming, but then having the two channel board fit into a 1455T2201 for total ease of casework...


 

 Dream big


----------



## ujamerstand

^^ bwahahahaha you must've predicted the future! Here's a smack on my head for not reading carefully. //>.>


----------



## Sathimas

Quote: 





ujamerstand said:


> .... But if the board could be in red and yellow to match the millett filament supply it would be even better!


 

 I'd prefer black boards - I built an exstata from the last "beta" run and those black
  boards are really beautiful! Far better than the common green ones.


----------



## cobaltmute

I'd vote clear, but I love the look of the bare copper.
   
  Black (and yellow) are apparently the worst choices for soldermask from a testing and manufacturing point of view.  The mask doesn't flow and cure as well, leading to a lower resolution mask.
   
  Apparently clear is the best, followed by green, red and blue.


----------



## runeight

You guys know what Henry Ford said when he was asked if people could have different colors on his cars? "They can have any color they want as long as it's black." Or something similar.


----------



## cobaltmute

No soldermask and this:
   
http://www.diystompboxes.com/smfforum/index.php?topic=83904.0


----------



## ujamerstand

The downside is that you get your hands all dirty in the process...


----------



## cobaltmute

The downside is exposed copper traces for you to short with a probe during setup...


----------



## stixx

I guess runeight won't sell insurance in case people do so...


----------



## runeight

Black boards, white silk. You will like them.


----------



## Sathimas

two thumps up ! 
	

	
	
		
		

		
		
	


	



   
  I think I'll take a set of boards too.
   
  - I do not need another headphone amp (got an M³, the exstata, a Meier Audio 2Move and soon a jibos-buffer-amp).
  - I don't have space to put it somewhere near the rest of my hifi-system
  - I don't listen to my Beyerdynamic DT880 much anymore since I have the stax ...
   
  Well, the only reason why I want it is because I love shining tubes 
	

	
	
		
		

		
		
	


	




 and building something.
  Just can't hold my hands still  - especially during the winter months.


----------



## sachu

If anyone wants it i have a set of pristine NOS matched pair of Telefunken 6GM8 tubes. The best i have heard on the EHHA. PM me if interested.


----------



## runeight

Gents, after much thinking and tinkering, it seems the only way to wire the two boards together is with ... wire.
   
  So, here's a new layout. You can see that the amp and PS are totally separate now. To use the onboard PS you just wire across the terminal blocks.
   
  I've had to make adjustments to the PS in order to place output caps on the regs for stability when it is operated stand-alone.
   
  Still talking with Jeff about how to get this out to you.


----------



## runeight

And just so you can also see the top layer ground planes.


----------



## FallenAngel

That looks too awesome to pass up, I think I'll really have to grab a set of these.   Great work Alex.


----------



## runeight

You know gents, now that we are this far, the next step would be pretty easy. That is, have two different boards. One board would have the rail PS at the back and the other board could have a DC heater PS. This would remove the nice channel separation that comes from each having its own reg section, but the linear regs are not bad and this may be a very small price to pay.
   
  Then you get everything you need. Almost the single board requested earlier, but maybe more flexible??
   
  I'd be willing to do this if you all want it, but it will make the boards more expensive since the lot counts will be cut in half for each board type. How much I don't know.


----------



## pabbi1

Can the Out be moved to the side of the board? In a perfect world, it would be optional on R or L, just to make a cleaner wire path to the jack.


----------



## johnwmclean

[size=medium][size=13.0px]Alex, I really like it.

 I know the added complexities of adding the heater circuitry to the pcb would prove a headache. BUT...
 Have you thought about including another separate matching pcb for the heater, this would make the build much easier, buying all the parts from one supplier. It could be included with the GJA kits additionally. 
 [/size][/size]


----------



## runeight

It won't be very hard to re-do the board by stripping off the rail PS and replacing it with a DC heater PS. Not hard at all. Then you have all that you need except for transformers, jacks, and pots.
   
  Al, I'll look at how to get the O/P off to the sides.


----------



## FallenAngel

How reasonable would it be to add a DC heater supply in the middle of the split supply?


----------



## ujamerstand

Let's not have a separate amp board with dc heater... Its not really that hard to build from scratch, and there's tons of single supply boards on the internet that could be adapted. Pete Millett has it on ebay too.


----------



## FallenAngel

Ooh, and it's regulated too.   Was just thinking of perfboard, but figured not everybody wants to work with it.


----------



## johnwmclean

Quote: 





ujamerstand said:


> Let's not have a separate amp board with dc heater... Its not really that hard to build from scratch, and there's tons of single supply boards on the internet that could be adapted. Pete Millett has it on ebay too.


 

 I’m just thinking about this as a package, remember this was supposed to be an easier build than the original EHHA, getting all parts from one source is way more attractive than sourcing parts and extra shipping costs. Not to say, this would be a bit of piss to do - so why not?


----------



## ujamerstand

The only reason that I could think of right now is to keep the manufacturing cost down. If Jeff will be packing kits for the boards, maybe he could include a breadboard, parts for a DC heater, and a detailed instruction to build one from scratch? It would be a good learning experience for those who never did it before.


----------



## runeight

Well, while we continue to talk, here's a board with a regulated 12.6VDC heater supply. Same amp section. 
   
  If you don't want the heater supply, maybe we can work it out so you can buy two of the amp boards with the rails PS.


----------



## FallenAngel

Ooh, here's an idea.  Selling 2-board sets... 1 with heater supplies, 1 with dual supplies for amp.


----------



## johnwmclean

Just curious as to how a 12.6VDC heater would work for each amp board as you’d only need one heater for a stereo amp? Am I not getting it?
   
  I really like the onboard psu, my thinking was to offer a DC heater pcb and components along with the ehha rev pcb and components.   
   
   
  Quote: 





runeight said:


> Well, while we continue to talk, here's a board with a regulated 12.6VDC heater supply. Same amp section.
> 
> If you don't want the heater supply, maybe we can work it out so you can buy two of the amp boards with the rails PS.


----------



## FallenAngel

If you want to go all-out, consider having both the heater and split-supply PCBs attached to the amp PCB.  It would offer quite a bit of flexibility but it would certainly be most expensive.


----------



## ujamerstand

down with more expenses!


----------



## Forte

Quote: 





ujamerstand said:


> down with more expenses!


 

 X2
   
  Still like the idea of each board having its own PS and the channel separation that comes from each having its own reg section. It is easy enough to find a heater supply or use AC heaters and this board setup makes it easier to build either 2, 3 or 4 channel builds.


----------



## beachgeek

Count me in for a set.  How much would the extra expense be? It would be nice to have the flexibility.


----------



## jdkJake

forte said:


> X2
> 
> Still like the idea of each board having its own PS and the channel separation that comes from each having its own reg section. It is easy enough to find a heater supply or use AC heaters and this board setup makes it easier to build either 2, 3 or 4 channel builds.







 I agree. Sometimes too much flexibility destroys the simple beauty of the implementation. I say keep the split supplies and don't worry so much about the heater supply. Unless you can jam both power supplies on a single board, I see no real advantage.

 I think of it this way, if you are financially challenged, just use AC on the heaters. It does not get any simpler, easier or cheaper as it is just a transformer. If you want to upgrade to DC, there are lots of boards out there that can do it, including a homemade perfboard.

 I think the DC heater muddies the water at this point.


----------



## jdkJake

fallenangel said:


> If you want to go all-out, consider having both the heater and split-supply PCBs attached to the amp PCB.  It would offer quite a bit of flexibility but it would certainly be most expensive.







 I just re-read this post. This might not be a bad idea. You could snap off the heater supplies for better location in the chassis and still have the split rail supplies for each board "at the back" .

 This would also limit it to one board to produce. Each board has an amp channel, a split-rail suplly at one end and a split dc heater suplly on the other. Each board would have everything you need to build an amp channel. You could even make the DC heater supply 6.3V as you would have one for each channel. Would make a clean kit as the board is a composite, yet modular representation of all the PCB you would need.

 I like it. Good thinking Fallen Angel!!


----------



## Beefy

Quote: 





jdkjake said:


> I think the DC heater muddies the water at this point.


 


 And why the specific need for _regulated_ DC heater? Isn't the goal usually to just get rid of the AC?
   
  You could have just a diode bridge and smoothing cap for about $5, no need for regulator or cap heatsink, very minimal board space......


----------



## cobaltmute

Beefy's idea is very good.
   
  I really like the idea of having everything for one channel on one board.
   
  I'll probably get a pair of boards,  can't guarantee a quick build though...


----------



## ujamerstand

Beefy's idea is excellent.


----------



## cobaltmute

Extend the board (on the tube) side to put a heater supply (bridge + cap), again on a small snap off segment.
   
  That way, you can use the board integrated, or you could snap off the heater or rail PS or both to do an all out board with your own supplies.


----------



## stixx

My 2 eurocents... leave the heater supply off so everybody can use what he likes best.  
	

	
	
		
		

		
		
	


	



  All of my headphone amplifiers but two (one SS, one AC = makes 6 total 
	

	
	
		
		

		
		
	


	




) use DC heaters either CRC or regulated.
  I have gotten used to really clean DC on the heaters...


----------



## bada bing

Quote: 





beefy said:


> And why the specific need for _regulated_ DC heater? Isn't the goal usually to just get rid of the AC?
> 
> You could have just a diode bridge and smoothing cap for about $5, no need for regulator or cap heatsink, very minimal board space......


 
   
   
  Unregulated DC off a bridge on a 12.6volt xformer tap yields about 16 volts dc. Wears out heater filaments unnecessarily fast.


----------



## cobaltmute

So use a 9v transformer if my math is right.


----------



## FallenAngel

9V transformer will be a little low unless you use Schottky diodes (which would be a good idea), 12V using normal diodes will work too, though might be a good idea to add a resistor to drop some voltage, better yet, CRC.


----------



## bada bing

Quote: 





cobaltmute said:


> So use a 9v transformer if my math is right.


 

 Sort of, you forgot the two diode drops. If you want exactly 12.6v unregulated you'd need a 9.9 volt xformer at the required current. There's another rub though, the actual voltage off a xformer depends on current out. Then there's the issue of line variations nationwide of about 10%. I suppose there's plenty of ways to skin the cat, but I personally would accept AC heaters or (preferably) use regulated DC. Tubes sound fine over a fairly large range of heater voltages, but running them too hot shortens tube life and too cold makes them cantankerous. I'd rather spend a couple bucks on a regulator than shorten the life of a few $10 tubes.


----------



## Beefy

Quote: 





bada bing said:


> Unregulated DC off a bridge on a 12.6volt xformer tap yields about 16 volts dc. Wears out heater filaments unnecessarily fast.


 


 You wouldn't be using a 12.6V tap, because this amp won't be using a 'tube' power transformer. The amp itself requires 30+30, so you would almost certainly have a separate heater transformer. You can precisely spec this transformer however you like, for whatever diodes you like.

  
  Quote: 





			
				bada bing said:
			
		

> Then there's the issue of line variations nationwide of about 10%. I suppose there's plenty of ways to skin the cat, but I personally would accept AC heaters or (preferably) use regulated DC.


 


 How is line variation OK for AC heaters, but not unregulated DC?


----------



## MisterX

I must be missing something... why not just use something along the lines of a voltage reference + op-amp for the heaters?
  (sort of like a dynalo PSU)
   
  Adding another rectifier, regulator and associated components seems kind of waste and you could power it all from a single transformer.


----------



## Beefy

Heater current is 0.33A. That would be an awful lot of wasted power and heat to knock down from 30V to 12V, wouldn't it? Not to mention doubling the current on the main power supply and transformer.
   
  [EDIT] I looked at the datasheet, and 6GM8 is 0.33A at 6.3V. I don't know why 12V was being talked about earlier. So regulation for each heater from a 30V rail would burn up 7.8W. That's pretty nutty!


----------



## jdkJake

12.6 in series. One supply for both tubes.


----------



## runeight

Good questions. MisterX were you thinking of just pulling from the rails? I'm not sure that you meant this, but it would burn a lot of wasted power. OTOH, we could consider a switching regulator (as in the CTH) which is much more efficient.
   
  Beefy I designed a 12.6V supply because I thought you would only have one and you would put the tubes in series. It is easer to make a regulated supply at 12.6V than it is at 6.3V from off the shelf transformers. A 12.6V transformer yields a high enough DC that at 350mA the regulator won't drop out. And, to be sure, I figured we would use an LDO regulator. This is all, as you know, very common.
   
  A simple rectified/filtered DC supply usually has problems with line regulation and almost always requires dropping resistors and yields a variable heater voltage depending on the line voltage. Whereas with a 12.6V regulated supply you get rock steady heater voltages.
   
  This was my reasoning, but we're still designing so we can go wherever there is consensus. I was just thinking that if one board had the rail PS and other the heater PS you would get everything you need with just two snappable boards.
   
  Edit: I see that jdklake's post squeezed in before mine.


----------



## johnwmclean

Quote: 





beefy said:


> [EDIT] I looked at the datasheet, and 6GM8 is 0.33A at 6.3V. I don't know why 12V was being talked about earlier. So regulation for each heater from a 30V rail would burn up 7.8W. That's pretty nutty!


 

 The 6H30 draws 0.9A, if your keen for rolling you’d need to step it up even further!


----------



## sachu

using the 6H30 in this amp is a mistake. That tube isn't used in the proper operating point. The 6GM8s sound vastly superior in this amp.


----------



## johnwmclean

sachu, can you elaborate “proper operating point”?
   
  ... the 6H30 is listed under possible alternatives on Alex’s site.


----------



## sachu

yeah..but the voltage and current on the plates is far too low and this tube is wasted..i mean it'll make music and all but is easily bested by the 6GM8.


----------



## runeight

Gents, the 6922 and 6H30 are listed as alternatives because they can be used and will come to a functional operating point. But they are both operating at well below normal voltages. 6922 is probably closer to a respectable operating point, but neither is optimal.
   
  6GM8 is the low voltage tube that fits the amp's design.


----------



## cobaltmute

Back on that heater supply thing, a discrete 6.2V regulator is not a lot of parts.
   

  R1 represent the heater load.
   
  Likely needs a cap on the output though.


----------



## ujamerstand

Won't we need heatsinks on the devices?


----------



## MisterX

Quote: 





> MisterX were you thinking of just pulling from the rails?


 
   
   
  Yes, My bad. I had assumed a reference to the the Dyanlo PSU made that clear but in hindsight it's kind of the same as interpeting a PCB layout without a schematic.
   
  Here's a link---->  
http://www.diamondstar.de/DynaloPSU544_schem_1024x.jpg
   
   
  Edit: LOL @ the forum spell checker


----------



## runeight

Quote: 





cobaltmute said:


> Back on that heater supply thing, a discrete 6.2V regulator is not a lot of parts.
> 
> 
> R1 represent the heater load.
> ...


 

 Yes, this would work. Essentially the opamp and the pass transistor are a very simple discrete equivalent of a standard linear regulator but using more parts. It would be easier, IMHO, to use an adjustable LDO regulator -- same number of parts in the end, but less circuit complexity because you only have three terminals to worry about.
   
  In either case it will need a heatsink on either the pass BJT or the linear reg and a cap on the output.


----------



## pabbi1

Any thoughts about the 6n27p in this amp?


----------



## cobaltmute

Quote: 





runeight said:


> Yes, this would work. Essentially the opamp and the pass transistor are a very simple discrete equivalent of a standard linear regulator but using more parts. It would be easier, IMHO, to use an adjustable LDO regulator -- same number of parts in the end, but less circuit complexity because you only have three terminals to worry about.
> 
> In either case it will need a heatsink on either the pass BJT or the linear reg and a cap on the output.


 

 I'm not sure why, but putting a cap on the output screws up the noise performance in sim
   
  I don't think you need a very large heatsink at all for this with either my circuit or a LDO 3-pin regulator.  You're not dropping a lot of voltage. 
   
  I just threw that out there to show that it would be simple to have a small discrete reg that would fit the duty.  As you said, a monolithic reg would be just as easy.


----------



## runeight

You're right about the cap and since the load is purely a resistor and burns a steady current we probaby don't need a cap.
   
  But, if the DC filter voltage is around 9V and if the tubes are in parallel this would be a drop of ~3V at 700mA which would be about 2W. Right? If so, then it will need a substantial heatsink. Please check my numbers.
   
  Also, my guess is that 2000uf is not a big enough filter cap when pulling 700mA. That is, the ripple into the regulator circuit might be pretty high. But I haven't actually checked it.


----------



## BoilermakerFan

Quote: 





pabbi1 said:


> Any thoughts about the 6n27p in this amp?


 

 I can't find curves for the 6n27p, but the 6n23p will be a pretty good alternate:
   
  http://www.tubes.ru/techinfo/HiFiAudio/6n23p.html
   
   
   
  With the latest Mod3 layout, it would be easy enough to bump the allowable diameter of C13/C14 up 5mm and clear bigger caps for 3A regs to allow speaker duty.  That's 3A per rail, so a 6A supply on 30V rails is a lot of potential power with an appropriate bump on the transformer secondaries current.  It looks like the D1-D4 diodes needs more space around them to allow us to use Stealth FREDs in the TO-220-2 package there though. 
   
  I'd come off the boards for heat sinking with 1/16" or 2mm thick aluminum to bond to larger heat sinks.  Pretty easy to make a 45deg bent piece for the V-regs and a "U" bend for the outputs.  Heck, you could go OTT and use a piece of 1/4" material and then mill it down to 1/16" for the transistor mounts, but have the 1/4" drilled and tapped for 4-40 to secure it at the stock heat sink mounting holes too.  Note to self:  Hit up Nate for a favor...  
	

	
	
		
		

		
			




   
  AC, you know I'm in for 4 boards for a BJT build.


----------



## BoilermakerFan

Not to muddy the waters too much, but how much would it cost to have the regulated heater supply board tacked on to one complete board?  Such that the order would be for 1/2 the boards with both a heater and PS board, then the other half ordered with just the PS board?  Of course, the mix can be sorted a little in ratios of whatever the fab needs to see, but it would make it easier to keep two parties happy.  I'd have no problem paying more for both to have regulated heater supplies on each board if the adder was only $15 or less.  That price being determined by Pete's charge for his two heater supply boards on eBay for $30.  I can certainly use the "extra" heater supply boards too for my other Cavalli Audio projects.  A simple reg swap and it can be a 1A, 3A, or 5A supply.


----------



## runeight

Yes, this could be done. But I bet it would be cheaper just to put the rail PS and the heater PS on the board and just order one type of board. This would double the quantity ordered and probably make it cheaper per board than two different boards one with smaller size.
   
  Adding a few sq mm to the original board (with rails PS) to include the heater PS will be a small increment in cost.
   
  But, in terms of casing, the boards are now significatly bigger.


----------



## BoilermakerFan

Quote: 





runeight said:


> Yes, this could be done. But I bet it would be cheaper just to put the rail PS and the heater PS on the board and just order one type of board. This would double the quantity ordered and probably make it cheaper per board than two different boards one with smaller size.
> 
> Adding a few sq mm to the original board (with rails PS) to include the heater PS will be a small increment in cost.
> 
> But, in terms of casing, the boards are now significatly bigger.


 
  That works for me if room can be made for the TO-220 rectifiers and there is a clear path off the board for the rails V-reg heat sinks.


----------



## cobaltmute

Quote: 





runeight said:


> You're right about the cap and since the load is purely a resistor and burns a steady current we probaby don't need a cap.
> 
> But, if the DC filter voltage is around 9V and if the tubes are in parallel this would be a drop of ~3V at 700mA which would be about 2W. Right? If so, then it will need a substantial heatsink. Please check my numbers.
> 
> Also, my guess is that 2000uf is not a big enough filter cap when pulling 700mA. That is, the ripple into the regulator circuit might be pretty high. But I haven't actually checked it.


 
   
  I think the numbers make sense. 
   
  The reason I said small heatsink is I was thinking of one small reg for each board (like I'd mentioned earlier), so it would only be 350ma of ~3V, so 1W.  That logic would also affect the size of the filter cap.
   
  A strip across the tube side of the board, about as wide as either the cap or the op-amp and you've got a regulator per board.


----------



## runeight

Yes, could be done and would work. The only risk that I can see is that the rectifiers (with all of their noise) and AC inlet would at the front of the board where the input section is. Whether this will introduce noise I cannot say.


----------



## cobaltmute

From a noise perpective, placing the heater AC right next to the input does not seem smart.
   
  It would be smarter to have the heater supply next to the rail PS.  You could again do the thin strip supply, which could be snapped off.  Leave it attached, and wire to the heater point on the amp board, or snap it off and run it beside the board from the back where the rail AC comes it to the front so the heater DC wire is like a short jumper.
   
  Just because I had time, I played with a quick layout of my schematic.  110mm x 15mm.

   
  Still needs mounting holes and terminal blocks, but it gets the idea across.  And it ended up with a decent heatsink.  R1 is just the load representation resistor.  Red is bottom ground plane.  Smoothing capacitor is sized so you can use a 16V Panasonic FM/FC 3300uF.
   
  I just want to say this again, my schematic or a adjustable regulator, like a LM317 makes no difference to me.  I only did this mock-up from my schematic as I already had the schematic so it was quick and easy to play with.
   
  Now to get onto a different suggestion:
  On the output of all the supplies - both rails and the heater, I think it would be prudent to place a LED.  Since the supplies could be built separate, it provides a small load on the supply to load them up for testing, as well as a indication of power and function.


----------



## runeight

I'm fine with this idea if you all want the heater strip at the back. Here's a board. It is 110mm x 150mm. No LEDs yet, but these are easy if this is the consensus.
   
  The rectifiers are vertical Schottkys (1N5822) to minimize Vf. If you use a 6.3V/1.5A transformer with low secondary resistance, this regulator might work alright.
   
  The component gap in the heater circuit is to provide a path for the 30-0-30 transformer leads to the rail supply. This could also be done with a hole in the rail strip near the terminal block.
   
  AC in is on the right, 6.3VDC on the left. The center terminal of the DC block goes to the SG.


----------



## FallenAngel

Looks wonderful Alex!


----------



## stixx

Looking good, and 110 x 150mm is still nice and compact!


----------



## runeight

OK. Then it seems like a slim heater board is getting good responses (so far).
   
  After thinking on it though I think I may just use an LDO. If you look at the opamp circuit the output of the opamp must be at least 1 BE drop higher than the output voltage. For a power transistor maybe this would be 700mV, possibly a hair more. Then the C of the transistor where the + rail of the opamp is attached must be at least one diode drop higher than the opamp output because opamps can usualy get their outputs about one drop from the rail. Say another 600mV.
   
  This means that the CE voltage on the pass device must be at least 1.3V and this is very close to an LDO. So I think we'll use an LT1085 instead. Your choice in transformers will matter a lot.
   
  But, with fewer components on the strip I can add a trimpot to adjust the voltage. If you have enough voltage at the filter cap you'll be able to run the heaters slightly hot to see if you like it.
   
  But, other than this minor change, it appears that we have a suitable result.


----------



## cobaltmute

All the logic makes sense, and I think being able to trim the voltage output is a very good thing.
   
  A 6.3V transformer seemed to be getting a little close for comfort for the discreet option.  A 9V would have seemed to be a little safer.


----------



## runeight

Here is the adjustable LDO version. 9V is safer for sure. 6.3V could work depending on transformer regulation and how over-specified the current rating is.


----------



## cobaltmute

Just printed the PDF to see scale - looks awesome.
   
  If you have your headphones wired up balanced style, you can run two boards in a true dual-mono configuration.  Two rail supplies, two heater supplies on completely separate boards.  Add separate transformers for each supply and you're rocking.
   
  Time to mod that spare HD-650 headphone cable I bought.  Also time to go design a dual mono dac.


----------



## dasein-geist

This newest modification is looking great.
   
  While I don't want to dig up old wounds, I am really enjoying how input from the community is directing the design; and, of course, I have to commend Alex on his willingness/ability to respond to said input. For me, this is exactly what the DIY community is all about. I appreciate the ability to be a part of it.
   
  Now I just have to decide if I still want to build the "original" EHHA (as a headphone/power amp setup) or this new revision. This new modification is very compelling (as an "all in one" setup), and it is making it very difficult to resist 
   
  Thanks again everyone who is participating in this process...


----------



## BoilermakerFan

Quote: 





dasein-geist said:


> This newest modification is looking great.
> 
> While I don't want to dig up old wounds, I am really enjoying how input from the community is directing the design; and, of course, I have to commend Alex on his willingness/ability to respond to said input. For me, this is exactly what the DIY community is all about. I appreciate the ability to be a part of it.
> 
> ...


 
   
  I'm not trying to muddy the waters, but how much power do you need for your speakers?  The existing RevA design could easily deliver 5W-6W/ch SE and if you do MOSFETs, then you can push it to close to 7W/ch @ 60degC on 2-1/2" heat sinks.  Balanced of course would be 11W-13W/ch.  You'd need bigger PS caps and probably 500mA-600mA secondaries, but that's achievable without off board heatsinks.  Go off board like I plan to do and you can push it higher.


----------



## BoilermakerFan

Quote: 





runeight said:


> Here is the adjustable LDO version. 9V is safer for sure. 6.3V could work depending on transformer regulation and how over-specified the current rating is.


 

 I'm assuming the trimmer would have enough adjustment to also let us dial down the heaters to 6.1V-6.2V or 12.2-12.4V, correct?  I like to run my heaters 0.1V-0.15V low to extend the life of my $15-$30 a piece tubes. 
   
  Is there room to fit the same heat sink as the PS regs on the heater supply so we can upgrade to 3A regs for other projects?  
	

	
	
		
		

		
			





  Should still have enough room to bring the secondaries through to the PS term block if the boards remained connected too.  Please?


----------



## beachgeek

Like it alot!


----------



## runeight

Trimmer would not have ability to go to 12V. Only from about 5.8 to 6.8. Reg size can be increased, but drawing more current from the heater supply affect many things, including the size of the filter cap.
   
  This is why I originally thought of making a 12.6V supply with plenty of supply voltage and an LDO with a big heatsink.
   
  But this new design is much smaller. Small enough to go on every board to power only that board's heaters.


----------



## runeight

Version with bigger heatsink. No room for wires.
   
  You all choose.


----------



## cobaltmute

Just a thought for the heater reg if you want 12V or more current:
   
  Snap the board off, put it on high standoffs and mount the diodes on the bottom.  This leaves lots of space for a bigger filter cap.  Range of the regulator is chosen by the resistors so you can choose appropriately to get 12V.  You can also lay the regulator down for a off-board heatsink.
   
  And the LT1085 is already a 3A reg.
   
  Use any or all of the above - lots of options.


----------



## runeight

3D


----------



## jdkJake

I like the smaller version better. Nice and compact, yet fully functional.
   
  EDIT: By smaller, I am referencing the heater options.


----------



## BoilermakerFan

Quote: 





runeight said:


> Trimmer would not have ability to go to 12V. Only from about 5.8 to 6.8. Reg size can be increased, but drawing more current from the heater supply affect many things, including the size of the filter cap.
> 
> This is why I originally thought of making a 12.6V supply with plenty of supply voltage and an LDO with a big heatsink.
> 
> But this new design is much smaller. Small enough to go on every board to power only that board's heaters.


 




  Quote: 





cobaltmute said:


> Just a thought for the heater reg if you want 12V or more current:
> 
> Snap the board off, put it on high standoffs and mount the diodes on the bottom.  This leaves lots of space for a bigger filter cap.  Range of the regulator is chosen by the resistors so you can choose appropriately to get 12V.  You can also lay the regulator down for a off-board heatsink.
> 
> ...


 

 I like the bigger heat sink and great ideas cobalt.  I'd keep the diodes on top and bottom mount or come off the side for the cap from the bottom for 12V, then mount the heater supply in the middle of the two amp boards so I'd run two tubes off one supply and have the spare heater board for my other projects.  
	

	
	
		
		

		
		
	


	



   
  Of course, if the group consensus is to keep it smaller, I'll side mount the PCB and come off the board with a bigger heat sink.  I can make it work, it's just easier with the bigger sink on the board. 
   
  Even if I kept it 6.3V, I'd still snap it off, so I'd rather have the bigger heat sink and no wire space.  Plenty of adjustment there too AC. 
   
  Will the PS D1-D4 fit TO-220 diodes?  I haven't printed the boards to scale to check. 
   
  Hey pabbi1, I have an ideal use for those spare Plitrons of yours.


----------



## stixx

I like the version from post #150 most... please finalize this one 
	

	
	
		
		

		
		
	


	



   
  In general I am truly amazed how much effort you (runeight) are putting into this just to please a handfull of solder slingers.. (so far). I really appreciate this!
   
  Maybe when the final board/kit/whatever hits the market it is time for another appreciation thread ...
   
   
   
  Last post for now..off into holidays


----------



## cobaltmute

My vote is the small heatsink version, plus add more pads so you could use a 7.5mmLS/18mm diameter cap instead of the 5mm LS one.
   
  That way if you wanted to give up the space for the wiring, you could use it by putting a big filter cap, like this one:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P5538-ND
   
  My thought is I'm going use a transformer with dual secondaries, and power each heater board off 1 secondary.
   
  Although, even with the big heatsink board, you don't have to use the big heatsink.  I suspect as a single heater supply, you might be able to get away with one of these and still have room for the wires:
http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=HS107-ND
  but don't quote me on that yet until someone does it.


----------



## runeight

Alright gents, I am about through. Multiple caps in both locations in the heater PS. Two style heatsinks.
   
  If you all agree to this, I'll add the LEDs to the rail supply.


----------



## pabbi1

So, the Out can't be moved to the side of the board?


----------



## dasein-geist

Quote: 





boilermakerfan said:


> I'm not trying to muddy the waters, but how much power do you need for your speakers?  The existing RevA design could easily deliver 5W-6W/ch SE and if you do MOSFETs, then you can push it to close to 7W/ch @ 60degC on 2-1/2" heat sinks.  Balanced of course would be 11W-13W/ch.  You'd need bigger PS caps and probably 500mA-600mA secondaries, but that's achievable without off board heatsinks.  Go off board like I plan to do and you can push it higher.


 
  Boilermaker,
   
  It's not the power output that is the concern; but, rather, the off-board heat sinks and the 1A regs. See this post by Alex (post #6 in this thread):
   
http://www.head-fi.org/forum/thread/506984/ehha-rev-a-interest-thread#post_6849272


----------



## cobaltmute

Quote: 





runeight said:


> Alright gents, I am about through. Multiple caps in both locations in the heater PS. Two style heatsinks.
> 
> If you all agree to this, I'll add the LEDs to the rail supply.


 
   
  One word:  Awesome.
   
  Multiple input and output cap and heatsink options on a board that small.  Excellent work.


----------



## BoilermakerFan

Quote: 





dasein-geist said:


> Boilermaker,
> 
> It's not the power output that is the concern; but, rather, the off-board heat sinks and the 1A regs. See this post by Alex (post #6 in this thread):
> 
> http://www.head-fi.org/forum/thread/506984/ehha-rev-a-interest-thread#post_6849272


 

 Right, off-board heat sinks aren't terribly difficult with the new board layout.  On board 2-1/2" heat sinks are good for 8W dissipation so you can get about 3W output off each sink, 6W/ch.  The regs can be replaced with 3A for each rail.  The transformer would have to be bumped up and you'll need bigger PS caps.  Some resistors will need to be bumped up to higher power dissipation ratings too. 

  
  Quote: 





runeight said:


> Alright gents, I am about through. Multiple caps in both locations in the heater PS. Two style heatsinks.
> 
> If you all agree to this, I'll add the LEDs to the rail supply.


 

 Looks great AC!

  
  Quote: 





pabbi1 said:


> So, the Out can't be moved to the side of the board?


 
   
  Actually, just rotating the amp board 180deg (or at least the swap the output TB for the heater TB) and put power input and heater term block in close proximity to the PS and have the input and output on opposite sides of the "front" edge would make it very easy to keep all the boards attached and a really compact build.


----------



## jdkJake

Quote: 





runeight said:


> Alright gents, I am about through. Multiple caps in both locations in the heater PS. Two style heatsinks.
> 
> If you all agree to this, I'll add the LEDs to the rail supply.


 

 Sweet.
   
  I'm in for four boards.
   
  Thanks for all the effort Alex. It is appreciated more than you know!


----------



## runeight

Since we seem to have mostly consensus, then this would be final. It has LEDs and a few resistor wattage adjustements. Note that the board also has provisions for an LED under the tube.
   
  pabbi1, the only clean way that I can think of to get the O/P to the edge is by giving you holes near the terminal block so you can run wires under the board. A hack at best.


----------



## nullstring

This is just a thought and in no way a demand or hardly even a suggestion.
   
  What if made the power supply shorter width wise, and longer length wise, and then put the heater supply to the left of it.
  I'd think that this would make more organizational sense. The power inputs would both be at the top, and such.
   
  Just to make sure you understand, I photoshopped yours to so you can see what I am getting at.
  Course, things would have to be reorganized to fit the adjusted spaces and that would take more time and effort.
   

  Again, just a thought.
  Feel free to ignore me. I really don't know what I am talking about.


----------



## runeight

nullstring, I've looked at this for a while and don't quite see how to fit everything. Good idea though. It does, however, make snapping off the heater supply separately without removing the rails more difficult.
   
  SInce we seem to be finished, here is what could be the final 3D.
   
  Jeff has emailed me so the next step would be to decide how to handle a board run. And the next step will be for me to post at BoM and for a few of you to vet it for component fits, especially cap sizes.


----------



## runeight

Gents, I would like to ask a major favor of one of you. My consulting life can get pretty busy and now that I've spent the time to get this to where the group is mostly happy with it, I'd like to reduce time a bit.
   
  The favor would be that I post a BoM and that one of you would kindly volunteer to be the BoM editor to get it into final condition for everyone. Once you do this, I can post some preliminary info to the CA website, including the BoM.
   
  And then, as mentioned, I am talking with Jeff now. There is one other thing to consider. Since the build is verified only once, it might be smart to have one or two of you agree to do a beta run. You'd have to agree to do an immediate build to verify that everything works as designed. Then when proven we can take the general distribution step. Any thoughts on this? If you are all willing, of course, we can go straight into the volume buy. Just trying to ensure that you all get things that work.


----------



## jdkJake

As far as the BOM goes, are you posting a hyperlinked spreadsheet or a web page? 
   
  Spreadsheet format == manageable effort, web page format == slightly more than manageable effort.  Let us know.
   
  As far a prototypes, well, I am your huckleberry.


----------



## runeight

I'll send you a nearly finished excel spreadsheet. All you have to do is to verify the part numbers and their fit on board. And then post this BoM to the thread for the group to review and take corrections/additions to create the final BoM.
   
  How's that?


----------



## jdkJake

Quote: 





runeight said:


> I'll send you a nearly finished excel spreadsheet. All you have to do is to verify the part numbers and their fit on board. And then post this BoM to the thread for the group to review and take corrections/additions to create the final BoM.
> 
> How's that?


 

 You have a PM.


----------



## runeight

Quote: 





jdkjake said:


> As far as the BOM goes, are you posting a hyperlinked spreadsheet or a web page?
> 
> Spreadsheet format == manageable effort, web page format == slightly more than manageable effort.  Let us know.
> 
> As far a prototypes, well, I am your huckleberry.


 


 PM sent. And you're on the beta signup list.


----------



## Forte

Cannot commit to an immediate beta build but would like a couple of boards when a group buy goes ahead.
   
  Thanks AC for all the effort with this design and the others you have given us.


----------



## studeb

i was going to jump in to the beta pit, but then i saw there were no tombstoned components....
   
  what happened to them? where is the fun with this?
   
  Seriously, anyone have a ballpark price to join the beta club - transformer, boards and components?
  i would not be able to start until after labour day if that eliminates me please say so


----------



## BoilermakerFan

Quote: 





studeb said:


> i was going to jump in to the beta pit, but then i saw there were no tombstoned components....
> 
> what happened to them? where is the fun with this?
> 
> ...


 
  Trust me, when you go with boutique parts, you'll have a chance to tombstone.  Try to fit Amtrans or NOS A-B carbon comps in there without tombstoning.


----------



## cobaltmute

Quote: 





studeb said:


> i was going to jump in to the beta pit, but then i saw there were no tombstoned components....
> 
> what happened to them? where is the fun with this?


 
  You could always tombstone the whole board in your case.
	

	
	
		
		

		
			




   
  I would put my name in for the beta run, but I know for a fact I would not get the board built fast enough to make people happy.  Mountain Biking in the summer or sitting in my basement soldering?  Not a hard choice as can evidenced by the fact that I've had a half built amp on the bench for over 3 months now.


----------



## runeight

Kind of a pathetic excuse, but since you drove the heater supply design, we can make an exception.


----------



## cobaltmute

As I sit here at work, waiting for the phone system techs to finish for the second day in a row, wondering what I could be building...


----------



## ujamerstand

woah, a little vacation from head-fi and this much progress? This is pretty impressive. I've got most of the parts to build a stereo pair of EHHA. just need the CRD and a few extra transistors for the changes in the revision. I would be happy to participate in the beta build.


----------



## runeight

Folks, been working with jdrjake on the BoM. There still is one remaining issue.
   
  If the heater PS is run from a 9V transformer, the DC voltage at the filter cap is likely to be at least 12.5VDC. This means that the regulator is dropping abou 6.2V at 350mA which is about 2.2W.
   
  If the larger heatsinks is 1.5" tall, the Aavid version is 11C/W. The temp rise will be 22C at minimum. In practice probably more like 30C putting the temp at >55C for a 25C ambient. And since the ambient is likely to be higher than 25C, we can guess the temp condition will be at least 60C at the case, higher at the junction.
   
  These devices are 150C devices, but still this is pretty hot.
   
  We should try to solve this before ordering prototype boards. There are two solutions that I can see:
   
  1. Use the larger heatsink like the ones on the amp boards. This will make the heater strip at least 5mm wider.
   
  2. Find some suitable 6.3V transformers that generate enough voltage such that the regulator won't drop out.
   
  What I mean but #2 is that, as you all know, transformers have a regulation factor. If the regulation is, say, 10%, the unloaded voltage would be 6.3VAC * 1.1 or about 6.96VAC. When the transformer is fully loaded its voltage will pull down to 6.3V.
   
  Now the tricky part is, how much the transformer pulls down depends on its maximum current vs. the actually loading and the secondary DCR. If the transformer is to supply 700mA (two boards) and it is rated at 1.5A then it won't quite pull down to 6.3V in actual operation. Thus we get a higher DC filter voltage.
   
  Secondly, since the filter cap is charge in large pulses, what the DC voltage is depends on the DCR of the secondary. The higher the current rating the lower the DCR and the higher the filter voltage.
   
  Thus, it is conceivable that we can find 6.3V transformers at >1.5A that will provide a DC filter voltage around 9V and this might be enough to keep the regulator from dropping out. OTOH, it might now.
   
  The absolutely safest solution is to increase the heatsink size and to use 9V transformers.


----------



## runeight

There is actually a third solution, which is to use a 9V transformer that is just adequate for the job such that it is operating a rated current and such that it will pull its voltage down enough to relieve the power dissipation.


----------



## runeight

And one more thing, replace the Schottkys with ordinary regs. If we do this, then it will be impossible to use any suitable 6.3V transformer. They will have to be 9V.


----------



## runeight

Yes, well, I guess I'm just working this through by posting. 
	

	
	
		
		

		
		
	


	



   
  If we use something like 9V/1A and replace the schottkys with UF4002 then the DC filter voltage might be around 10.5V depending on regulation. Then the power dissipation is more like 1.2W and this is manageable for the larger heatsink at 1.5". Easily manageable for a 2" version.


----------



## runeight

Yes, this is the right way to do it if you all don't mind having to find 9V transformers for the heaters.
   
  9V/1A would work out ok.
   
  If you all agree to forego the 6.3V option, I'll change the boards. And then we can order two sets for our two prototypers.


----------



## cobaltmute

I have my moments where I can't figure stuff out, and one of those moments for some reason, is transformers and ratings.
   
  How would this one do for the heaters:
http://www.antekinc.com/details.php?p=9
   
  And about the beta builds - if I could have boards in front of me for Sept 1, I could spend some time at the start of my vacation building an amp.


----------



## jdkJake

I prefer to have margin rather than count on surplus.


----------



## jdkJake

Quote: 





cobaltmute said:


> I have my moments where I can't figure stuff out, and one of those moments for some reason, is transformers and ratings.
> 
> How would this one do for the heaters:
> http://www.antekinc.com/details.php?p=9
> ...


 
   
  Actually, that is a pretty good match for the 6.3V implementation. Better than anything I found. Certainly more affordable as well.
   
  Nice find CobaltMute.
   
  Hmmm. Big decision point coming up here. Play it safe or take out the gold teeth and see how they roll....


----------



## runeight

Maybe the best way is for builders to make a build-time choice in rectifiers.
   
  The choice will be: Schottky or normal. It is possible to allow for installation of either type.
   
  Schottky will work for many 6.3V transformers (and the 7V above) but potentially lead to too much power dissipation in 9V installations.
   
  Normal will work for 9V transformers, but make it impossible to use typical 6.3V transformers and maybe even the 7V that cobaltmute found.
   
  How about I add this option to the board: pads for both rectifier types? And then you guys can choose when you build the amp?


----------



## ujamerstand

I was originally going to use these for my EHHA: 
   
  http://www.mouser.com/ProductDetail/Triad-Magnetics/F18X/?qs=sGAEpiMZZMv4oUrzpPKU3AviJOQLJDDHa9uH%252boEwDrM%3d
   
  http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=HM508-ND
   
  or
   
  http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=237-1256-ND
   
  Is there anything wrong with using these for DC heaters?


----------



## cobaltmute

Quote: 





runeight said:


> Maybe the best way is for builders to make a build-time choice in rectifiers.
> 
> The choice will be: Schottky or normal. It is possible to allow for installation of either type.
> 
> ...


 

 Since we've added just about every other option for the heater board, sounds like a plan.


----------



## BoilermakerFan

Quote: 





runeight said:


> Maybe the best way is for builders to make a build-time choice in rectifiers.
> 
> The choice will be: Schottky or normal. It is possible to allow for installation of either type.
> 
> ...


 
  There is a third, or is it fourth, choice is a full custom transformer such as one from SumR.  Richard could wind a 6.6V, a 7.1V, or 8.2V secondary heater winding.  Electra-Print and any of the other custom toroid or E-I iron guys can do the same too.  For builders on a budget it's not a low cost option, but it will maximize the performance and efficiency of the amp.  I won't try to confuse the issue too much, but a good winder can manipulate the regulation and DCR to some degree too.  I'm working with SumR on a custom where this manipulation is being done for a shunted PS. 
   
  If there are enough peeps interested in custom iron for the EHHA RevA, I can quarter-back this project and work with Richard to sort the correct secondary to achieve the most efficient 6.3V for the 6GM8, 6n23Pi, and 6DJ8 heater demands.  I prefer shielded and fully encapsulated units, but I would have him quote it as just banded, and S&FE.  I'll also ask Richard to provide dimensions for both.  The unit would be sized to power two boards and two heater PS boards so that two would be needed for a balanced build.   
   
  Also since the tube is sticking up off the board in the socket, trying to keep the heat sinks height minimized really isn't necessary unless the builder plans to only pop the tubes up through the case, but that will make the EHHA look like another amp and, meh IMO.  So a bigger heater PS V-reg heat sink isn't that big a deal except for the extra heat and reduced efficiency of the circuit.


----------



## runeight

Maybe this will be the last change. Heater rectifiers can now be Schottky (1N5822) or UF4002.


----------



## runeight

How many proto builders do we have gents?
   
  jdrjake and ujamerstand.
   
  If you guys can build fairly quickly this will be enough.
   
  For the rest of you, you may be wondering why another test run since the amp has already been proto'd.
   
  One reason is that we have a new heater supply. It will almost certainly work, but it hasn't been tested.
   
  The primary reason is that as a result of this discussion the original board has been significantly changed. And while I'm pretty sure all is well, there is some small possibility that I have made a mistake somewhere. I'd like to verify board integrity before we order 25 or 50 boards and you all get something that is broken.
   
  It is a bit cautious I know, but I have been bitten by this once or twice.
   
  So if you all can bear with the beta builders this will ensure a good result for everyone else.
   
  Beta builders I am ready to order boards, 2 for each of you, if you are ready.


----------



## sachu

What are the board dimensions Alex?


----------



## fishski13

Alex,
  if you need another Beta builder, i'm game.


----------



## cobaltmute

I might make the suggestion that the power supply and heater supply use the same rectifier diodes.
   
  As I said I've had a bit of change of heart, and I'll put my namein  for the beta.  I'll make time for this.


----------



## fishski13

i'll bow out if needed as colbalt is now willing to Beta.


----------



## ujamerstand

If the boards arrive in toronto before august 30th, Cobaltmute could probably start on prototyping faster than I do. I won't be back in Toronto until the 30th.
   
  Otherwise, I'm ready. (Unless you really want to do it, cobalt?)


----------



## cobaltmute

Quote: 





fishski13 said:


> i'll bow out if needed as colbalt is now willing to Beta.


 

 My opinion is the more beta builders the better.  More builds equals more chances to test that everything works.
   
  Plus I'm thinking of a BJT build.  What are the rest thinking of?  It would be important to have both MOSFET and BJT builds.


----------



## cobaltmute

Quote: 





ujamerstand said:


> If the boards arrive in toronto before august 30th, Cobaltmute could probably start on prototyping faster than I do. I won't be back in Toronto until the 30th.
> 
> Otherwise, I'm ready. (Unless you really want to do it, cobalt?)


 

 As I said, I put my name in to add to the other builders names, not to replace anyone.  The more builders, the more testing, the better the board.


----------



## stringgz301

Alex - I'd like to be a beta.


----------



## fishski13

Quote: 





cobaltmute said:


> My opinion is the more beta builders the better.  More builds equals more chances to test that everything works.
> 
> Plus I'm thinking of a BJT build.  What are the rest thinking of?  It would be important to have both MOSFET and BJT builds.


 

 MOSFET.  assuming no major PCB fab issues, what's the timeline for getting the beta testing done?


----------



## ujamerstand

I've already have the MOSFETs in my hands, so I would be doing the MOSFET as well. I could get my hands on some BJT, but its going to take longer.


----------



## runeight

Well, it looks like there are about six of you now.
   
  I think the fab will be 1-2 weeks for the boards to get in my hands and then whatever the transit time is to you.
   
  I think 2-3weeks build time would be good. Less if possible.
   
  Gents, normally with one or two proto builders, I pay for the boards and you pay for the parts. At the cost of two proto boards this is generally very fair and spreads the risk between me and you.
   
  However, if we have 5-6 beta builders then the board cost goes up even though price per board goes down. In this case, I'll probably have to ask you to pay for the boards because I can't go in for that size of an order. My apologies, but this is for you to consider please.


----------



## stringgz301

I'm happy to pay for the boards, but could also bow out of the proto phase if others don't.


----------



## cobaltmute

Quote: 





stringgz301 said:


> I'm happy to pay for the boards, but could also bow out of the proto phase if others don't.


 

 Ditto.


----------



## fishski13

Quote: 





cobaltmute said:


> Ditto.


 

 ditto, depending on the price of a board.


----------



## ujamerstand

Quote: 





cobaltmute said:


> Ditto.





   Agreed.


----------



## runeight

Thanks. So we have:
   
  stringgz301
  cobaltblue
  fishski13
  ujamerstand
  jdkjake
   
  I should order 10 board then??


----------



## sachu

Put me down as well Alex. Will build the BJT version.


----------



## cobaltmute

Quote: 





runeight said:


> Thanks. So we have:
> 
> stringgz301
> cobalt*mute*
> ...


 

 Fixed.
   
  Anyone got a good line of the tubes?  Might as well order them now..
   
  Planning juices are going now 
	

	
	
		
		

		
			




   
  My plan, at the moment, is BJT 2SC2238/2SA968 with low gain and low feedback.  PGA2310 volume control.


----------



## sachu

Cobalt..am going to be building with the same output devices as well.
  Do you have a board for the PGA2310/20 volume control? I've come to love it..let me know if you have an extra couple of boards of those and programmed micro controllers.


----------



## jdkJake

boilermakerfan said:


> There is a third, or is it fourth, choice is a full custom transformer such as one from SumR.  Richard could wind a 6.6V, a 7.1V, or 8.2V secondary heater winding.  Electra-Print and any of the other custom toroid or E-I iron guys can do the same too.  For builders on a budget it's not a low cost option, but it will maximize the performance and efficiency of the amp.  I won't try to confuse the issue too much, but a good winder can manipulate the regulation and DCR to some degree too.  I'm working with SumR on a custom where this manipulation is being done for a shunted PS.
> 
> If there are enough peeps interested in custom iron for the EHHA RevA, I can quarter-back this project and work with Richard to sort the correct secondary to achieve the most efficient 6.3V for the 6GM8, 6n23Pi, and 6DJ8 heater demands.  I prefer shielded and fully encapsulated units, but I would have him quote it as just banded, and S&FE.  I'll also ask Richard to provide dimensions for both.  The unit would be sized to power two boards and two heater PS boards so that two would be needed for a balanced build.
> 
> Also since the tube is sticking up off the board in the socket, trying to keep the heat sinks height minimized really isn't necessary unless the builder plans to only pop the tubes up through the case, but that will make the EHHA look like another amp and, meh IMO.  So a bigger heater PS V-reg heat sink isn't that big a deal except for the extra heat and reduced efficiency of the circuit.







 Interesting option. How much do you think something like this would cost? Ball park.


----------



## runeight

OK then, 6 board sets. That's 12 boards altogether. You guys wil remember that this is a beta run and these boards are changed from the original proto. Enough said.


----------



## runeight

Someone asked about board size - 110mm wide x 150mm long.
   
  Edit: Snap off the heater supply and it is 130mm long. Snap off the rails PS and it is 85mm long.
   
  The actual amp board is pretty small.


----------



## runeight

Regarding the BJT version. jdkjake and I will provide the alternate parts for this version and the design center transistors will be MJE243/253. Anything that biases close to these should work.


----------



## jdkJake

Just a quick note, the MJE243 seems to be backordered at both Mouser and Digikey.
   
  So, I would look to source those elsewhere as the Mouser expected delivery date is in November!?!


----------



## runeight

Hmmm. These transistors are a nice choice. Too bad. I guess we could look for others, but these are generally available worldwide without too many problems. Except for now.


----------



## jdkJake

I think MCM might have them.
   
  I have never ordered from them. Are they reliable?


----------



## MrSlim

Newark has the MJE243/253G at the moment.. although only 32 of the 243s
   
  Allied does also..


----------



## sachu

MCM are reliable yes..the Toshiba 2238/968 devices should do much better here IME.


----------



## cobaltmute

Newark and MCM are the same people


----------



## BoilermakerFan

Quote: 





cobaltmute said:


> Fixed.
> 
> Anyone got a good line of the tubes?  Might as well order them now..
> 
> ...


 

 I'm considering selling my (4) NOS Amperex Holland 6DJ8s.  Probably ask $75 shipped for the quad.  These are not BBs though.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> Interesting option. How much do you think something like this would cost? Ball park.


 
  My two 120/240 primary 60VCT @ 400mA ea were $126 shipped.  Figure another $20-$35 or so for the heater windings.  So probably $155-$175 for two, or $75-$85 ea., just an estimate.  I can't see S&FP units being more than $95 ea.


----------



## sachu

way too spendy if you ask me..rather go for off the shelf Toroids and a secondary heater transformer. Add a heater delay and you are all set.


----------



## jdkJake

All,
   
  A couple of heater toroid choices to consider. These are more costly than the Antek. Not sure who makes better gear.
   
  Under consideration (sourced from digikey):
   
  7V 1.43A (10VA) - TE62040-ND  (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=TE62040-ND)
  9V 1.11A (10VA) - TE62041-ND  (http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=TE62041-ND)
   
  Manufacturer: AMVECO: http://www.amveco.com/pdf/Amveco_Catalog.pdf#page=25


----------



## fishski13

re: TXs
   
  i'm going to give A.L. a call tomorrow for quotes on the Y236207 30V+30V/0.83A and Y236001 9V+9V/0.83A:  http://avellindberg.com/transformers/y23_range_specs.htm


----------



## jdkJake

Just a quick update from the BOM front...
   
  Still being finalized, checked, rechecked and checked again.  
   
  Current _*ESTIMATED*_ parts cost for populating a _*SINGLE*_ board, MOSFET Amp, Split Rail PS, 6.3V Heater PS (minus LED's, LED Resistors, Tube sockets, Tubes, Transformers, AC Socket/Switch and mounting hardware) is running right at about $82 USD. (All parts sourced from Mouser)
   
  Not too bad. Not too bad at all!


----------



## jdkJake

Quote: 





fishski13 said:


> re: TXs
> 
> i'm going to give A.L. a call tomorrow for quotes on the Y236207 30V+30V/0.83A and Y236001 9V+9V/0.83A:  http://avellindberg.com/transformers/y23_range_specs.htm


 

 Thanks fishski13!
   
  Can you also ask about the Y236107 30-0-30/0.5A (30VA) as well? I have reason to believe Alex is thinking this would suffice.


----------



## cobaltmute

<threadjack>
  Quote: 





sachu said:


> Cobalt..am going to be building with the same output devices as well.
> Do you have a board for the PGA2310/20 volume control? I've come to love it..let me know if you have an extra couple of boards of those and programmed micro controllers.


 

 I do have a board - happens to be my avatar 
	

	
	
		
		

		
		
	


	



   
  Bigger pics:


   
  They are "alpha" boards.  They work, but they do need a revision.
   
  Some issues with them:
  - there is some parts that need to be mounted opposite to the silkscreen.
  - they were meant to be dual input/one output (source selection), but due to a design flaw this does not work directly on the board  - there is a way to hack this though, I believe.
  - they do have an output to drive a SparkFun SerLCD module.  While this works, I find the LCD module flaky - you can lock it up, so not advisable.
  - labels get hidden under terminal blocks
  - need to change the TO-92 regs for the PGA chips to TO-220
   
  Some pluses:
  - on board regs for both digital and analog sections.  This allows you to use either PGA2310 or PGA2320.  The board does need a split supply.
  - boards can be stacked for balanced use.  This was designed, but I haven't tested it yet.  You can also use this feature to hack around the issue with the input selection (although you still need to airwire some resistors).
  - Single or two inputs, full mute or -30dB mute, PGA gain above 0dB or not, and encoder type can all be set with jumpers so no coding.
  - the input selection LED blinks to show if the mute is active.
  - it is designed to work with a rotary encoder with switch.  Short push of the switch mutes, long push of the switch changes source, if enabled.
   
  The only part of the code that I have not written is storing the volume so over a power down the module resets to basically a full mute.  The code isn't hard, I just haven't done it yet.
   
  Let me repeat: "alpha" boards.  So if that doesn't scare you, I do have a bunch of boards as Gold Phoenix sent me double my order.  I do have ATmega chips I can program as well.  There will be a "beta" board later, and things will change on it - so don't ask for one of these if you can't accept that.
   
  If there is interest, we will have to start another thread.  And I will be definitely limiting participation..
   
  </threadjack>


----------



## cobaltmute

I was hoping this for the main transformer
http://www.antekinc.com/details.php?p=25
   
  and the 7V (http://www.antekinc.com/details.php?p=9) for the heater.
   
  Compared to the Digikey parts, it saves me about $20, and I've already got a couple of others transformers I want to order from Antek.


----------



## runeight

So, on the transformer ... bigger is not better.
   
  A single 30-0-30/400mA transformer will do for two channels. Anything with higher spec than this runs various risks for power dissipation in the rail regulators and/or too much voltage into the regulator.
   
  My strong suggestion is to find one with this or close to this spec.


----------



## fishski13

Quote: 





jdkjake said:


> Thanks fishski13!
> 
> Can you also ask about the Y236107 30-0-30/0.5A (30VA) as well? I have reason to believe Alex is thinking this would suffice.


 

 will do.  i'm guessing around $45-50 for both.
   
  i just finished desoldering the 9-pin PCB tube sockets from my remnant Bijou boards 
	

	
	
		
		

		
		
	


	




.


----------



## fishski13

Alex,
  do you still recommend a heater-switch/delay?  as i understand, it's nothing to do with cathode stripping, but the the possibility of the amp passing one of the rails until the cathode is heated and conducting?  what about these thermistors on the primary side (L and N) of only the PS TX instead?  http://search.digikey.com/scripts/DkSearch/dksus.dll?Cat=656273&k=cl-60


----------



## runeight

Yes, this is a good idea. And yes, it's simply to prevent the output from slamming to one rail while the tube heats up. But, the gentleman who built the proto has reported that he never sees an excursion larger than about 1.2VDC on the output, powering up or down. This is not bad and headphones can stand this.
   
  And although this should be reproducible across builds, we don't have enough data to know for sure. Thus, warming up heaters first is a good idea, but may not be strictly necessary in this design.
   
  You can try the thermistors, they may do the trick, but I never quite know how to select their specs.


----------



## cobaltmute

Quote: 





runeight said:


> So, on the transformer ... bigger is not better.
> 
> A single 30-0-30/400mA transformer will do for two channels. Anything with higher spec than this runs various risks for power dissipation in the rail regulators and/or too much voltage into the regulator.
> 
> My strong suggestion is to find one with this or close to this spec.


 
   
  I'm not worried about voltage input into the regulators, more about dissipation.  For the cost, I can always buy one, and test since I'm going to order other stuff as well.


----------



## FallenAngel

Not to take this off track, and I'll gladly do this over PM or another thread, but how about a small group-buy for Antek transformers (especially nice for Canadians to save lots on shipping).


----------



## BoilermakerFan

Quote: 





sachu said:


> way too spendy if you ask me..rather go for off the shelf Toroids and a secondary heater transformer. Add a heater delay and you are all set.


 
   
  I prefer cleaner, hum-free iron.  
	

	
	
		
		

		
			




   
  I asked Richard for a quote on the following spec:
   
  120/240 primary, (2) 60VCT @ 200mA, and (2) 7V @ 500mA in both banded open as well as shielded and fully encapsulated.  The dual voltage primary adds $5 or $10 to the cost, but IMO is worth the little extra up front to allow sale of the unit to most of the world later. 
   
  Electra-Print units under 200VA have generally been within $10-$15 of the SumR shielded and encapsulated iron.  The E-I PS iron would yield cleaner power coming in, but it's a larger package to fit in a chassis. 
   
  EDIT:  Broskie has a nice little two position AC power switch kit for $6.  Off-winding 1 power on-winding 1 and winding 2 power on.  So it's a simple, low cost way to power up the heaters, then power up the amp.  No TDRs, no more complex than it needs to be, but it's just a simple rotary switch so no cool illuminated momentary power push buttons either...


----------



## cobaltmute

Quote: 





fallenangel said:


> Not to take this off track, and I'll gladly do this over PM or another thread, but how about a small group-buy for Antek transformers (especially nice for Canadians to save lots on shipping).


 

 I'm ordering three or four from Antek so I'm in.


----------



## fishski13

Quote: 





boilermakerfan said:


> I prefer cleaner, hum-free iron.
> 
> 
> 
> ...


 

 for those looking for an EI in the PS, Partsconnexion has the Hammond 167G60 60V C.T./.5A: http://www.partsconnexion.com/hammond_fil_encl.htm
   
  for heater EI, no reasonably sized "matching" TX from the 167-series.  the 266-series is a little "nicer" to look at compared to the 166-series and a little more flexible with dual primaries and secondaries.  this one would work, but the lead-time is 4wks: http://search.digikey.com/scripts/DkSearch/dksus.dll?lang=en&site=US&WT.z_homepage_link=hp_go_button&KeyWords=266G14&x=0&y=0
   
  otherwise, the "economical" 166J8 (8.5V C.T./1A) or 166L8 (8.5V C.T./2A) should work with with UF4002 rectifiers in the heater supply?  http://www.mouser.com/ProductDetail/Fairchild-Semiconductor/UF4002/?qs=sGAEpiMZZMtEwUVCuofpuGhtK2I2zIFHcv3dRFvTnkM%3d.  add a single 166G60 (60V C.T./0.5A) in the PS.  Partsconnexion has a good selection of 166-series:  http://www.partsconnexion.com/hammond_fil_open.html.  only $43 for both the heater and PS TX.


----------



## jdkJake

boilermakerfan said:


> I prefer cleaner, hum-free iron.
> 
> 
> 
> ...







 The shielded and encapsulated version still sound interesting. Especially since I ultimately want to do a single enclosure with this amp. 

 What kind of lead time do those usually have? 

 Still looking for options, keep them coming.


----------



## ujamerstand

Quote: 





cobaltmute said:


> I'm ordering three or four from Antek so I'm in.


 

 Count me in for the antek as well.


----------



## cobaltmute

Quote: 





runeight said:


> Regarding the BJT version. jdkjake and I will provide the alternate parts for this version and the design center transistors will be MJE243/253. Anything that biases close to these should work.


 

  
  Quote: 





jdkjake said:


> Just a quick note, the MJE243 seems to be backordered at both Mouser and Digikey.
> 
> So, I would look to source those elsewhere as the Mouser expected delivery date is in November!?!


 

 I have 2 each of the MJE243/253 so I have no need of them.
   
  Is there a reason you guys want to supply to parts - I have no issue with ordering for myself.
   
  I know I said I was going to build with 2SC2238/2SA968, but I think I'm going to change that.  When I was looking on my bench to check for the MJEs, I realized I have some other transistors that may be a good fit - 2SB1186A and 2SD1763A.  Extras from a Kumisa build.


----------



## runeight

No intention to supply parts. I just meant that we'll provide part changes in the BoM for the BJT version.


----------



## cobaltmute

Ahh.  Misunderstood what you said.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> The shielded and encapsulated version still sound interesting. Especially since I ultimately want to do a single enclosure with this amp.
> 
> What kind of lead time do those usually have?
> 
> Still looking for options, keep them coming.


 

 Lead times from SumR are generally about one week with encapsulated units.  Less with the open, banded units by two days or so.
   
  Here is the pricing for 120/240 primary, (2) 60VCT @ 200mA, and (2) 7V @ 500mA:
   
  [size=x-small]- fully encapsulated and shielded: US $ 74/ea[/size]
  [size=x-small]- just with a core band and mounting hardware: US $ 53/ea[/size]
   
  [size=x-small]If a few guys are interested, then I'll ask Richard to assign a part number to each version and then you can just contact him to tell him you want the p/n: **** trafo for the EHHA, then provide your address to determine shipping, he'll send you a total, and your off[/size]. 
   
  I'll wager these units are about 3-1/4" in diameter and about 2" high, but I've asked for the dimensions.
   
  So, the $53 unit will be smaller than two Hammonds and probably not hum or vibrate like the lower end Hammonds are prone to doing.  Edcors would be another alternate choice for E-Is too, but I haven't looked at their options.


----------



## BoilermakerFan

I was close, but had them mixed up a bit...
   
  The dimensions:
   
  [size=x-small]-non encapped:    OD: 3.5" x HT:1.1"[/size]
  [size=x-small]- encapped in box: OD: 4  1/8"  x  HT: 2 1/8" [/size]


----------



## keyid

Been awhile since picking up the soldering iron and ready for another project. Put me down for a set of stereo boards.


----------



## fishski13

i called A.L.:
  Y236001 = $20.23
  Y236107 = $22.47


----------



## jdkJake

Quote: 





boilermakerfan said:


> Lead times from SumR are generally about one week with encapsulated units.  Less with the open, banded units by two days or so.
> 
> Here is the pricing for 120/240 primary, (2) 60VCT @ 200mA, and (2) 7V @ 500mA:
> 
> ...


 

 I am still interested. Might kill me in shipping though.
   
  EDIT: Deleted obvious question -- doh!!


----------



## runeight

The Avel transformers (and most other toroids and many EI) will have dual secondaries where you tie two of the secondary leads together to form the CT for 30-0-30.
   
  A few EI will have one CT secondary.


----------



## jdkJake

Thanks, I caught that and edited my previous post.
   
  Man, you are FAST!!


----------



## BoilermakerFan

The SumRs quoted have two separate secondaries, 60VCT, or 30-0-30, each is 200mA, so one set would be for one board, the other set for the second board.  It also has a separate winding for each heater supply so it has a total of four secondary windings. He includes a wiring diagram so you'll know what wires are what, but quick DCR checks confirm everything is labeled correctly.  
	

	
	
		
		

		
			




   
  He ships via Canadian Post, so it hasn't been bad.  I had two shipped Express for CJ and they arrived two days later for $21.  Regular shipping on two units about the same size as these was $14 IIRC, maybe less.


----------



## sachu

I'd rather go for one single 500mA secondary 30-030 winding..


----------



## cobaltmute

I hate to say it, but the encapsulated SumR looks very, very interesting.  Local shipping as well.
   
   
  With the comments about heater start-up delay and offset is an epsilon12 a good choice as well?


----------



## sachu

an epsilon12 will indeed be needed if you plan on leaving your headphones plugged in during turn on and turn off. Though the one proto amp is reported to keep the DC offset under 2 volts and usually the servos kick in 5-6 secs after turn on. But I usually bypass the E12 and just unplug my headphones everytime i turn on/off the amp .


----------



## BoilermakerFan

Quote: 





cobaltmute said:


> I hate to say it, but the encapsulated SumR looks very, very interesting.  Local shipping as well.
> 
> 
> With the comments about heater start-up delay and offset is an epsilon12 a good choice as well?


 
  Talk dirty to me and I might post some transformer pron for you.  
	

	
	
		
		

		
		
	


	




  I just need AC to design a 3" round Cavalli Audio DIY logo sticker to slap on top of them!
   
  Heater start-up time delays are always a good choice with SS PS.  I prefer the Row, row, row your boat method with Broskie's cheap switch, but my chassis is a vintage case so illuminated PBs look out of place...


----------



## cobaltmute

It's a double edged sword:
  - leave your headphones plugged in and have start-up offset
  - plug in your headphones after turn-on and have to deal with the issues of inserting a TRS plug and the short to ground (I always turn the volume down on insertion)
   
  Yes, I need to re-cable to XLR.
   
  Time to go order 2 epsilon12s, me thinks.


----------



## ujamerstand

Two epsilon12s? Doh. I forgot that the boards now have separate PS. Another run to the amb shop for me...


----------



## cobaltmute

Another reason for two - and I stand to be corrected on this by amb or any other, but it my interpretation of the schematic:
   
  The op-amp compares the *sum* of both channels offset.  If Left goes +20V and Right goes -20V, the offset is 0V and the epsilon12 will not trip.
   
  Odd of both channels going the opposite way the same amount - slim, but it makes me happy to cover that case by one board per channel.
   
  Anybody have any comments about the 6N27P?  It is apparently equivalent to the 6GM8.


----------



## sachu

Haven't tried the 6N27P...ut have read good things from Aikido owners on other boards, even claims of being better than the 6GM8 tubes.


----------



## BoilermakerFan

6N27Pi is a 100 Mu tube.  6GM8 is 14...  Way too much gain. 
   
  EDIT:  I'm finding conflicting reports of the Mu, some sites list 100, other list 16.


----------



## BoilermakerFan

Quote: 





boilermakerfan said:


> 6N27Pi is a 100 Mu tube.  6GM8 is 14...  Way too much gain.
> 
> EDIT:  I'm finding conflicting reports of the Mu, some sites list 100, other list 16.


 

 Well, Broskie has it listed as an alternative to the 6GM8, so I think the pages I found with it listed at 100 Mu instead of 16.1 are wrong...  Ugh, I'll call it lost in translation.


----------



## jdkJake

Quote: 





boilermakerfan said:


> The SumRs quoted have two separate secondaries, 60VCT, or 30-0-30, each is 200mA, so one set would be for one board, the other set for the second board.  It also has a separate winding for each heater supply so it has a total of four secondary windings. He includes a wiring diagram so you'll know what wires are what, but quick DCR checks confirm everything is labeled correctly.
> 
> 
> 
> ...


 
   
  Sounds like a winner to me. A few dollars more for a single part that is shielded and encapsulated works for me. I want to minimize case size.
   
  Let us know when you get a part number. I will put it on the BOM as an alternate.
   
  BTW, we hope to have a first cut BOM for review later this evening. For now, back to the day job....


----------



## jdkJake

Quote: 





sachu said:


> I'd rather go for one single 500mA secondary 30-030 winding..


 


 I like the dual windings. If one board heads south, you don't get a sudden current rush into the other. I was going to use two seperate toroids if we didn't go custom.


----------



## FallenAngel

$53 for transformer for 2 boards form SumR does look VERY good, probably even cheaper considering shipping within Toronto than A.L. with shipping from US.


----------



## BoilermakerFan

Yes, I had him do two boards per transformer, so a balanced build still needs two transformers, but they are in fact two separate SE builds and can always be separated and sold off that way.  
	

	
	
		
		

		
			





  Plus I like having the option of wiring the amp with two separate pots for balance control and wire the outputs to either speaker posts, dual TRS jacks, or a 4-pin XLR.  It also makes it really easy to audition tweaks side by side with a switch box.


----------



## bada bing

Quote:


boilermakerfan said:


> 6N27Pi is a 100 Mu tube.  6GM8 is 14...  Way too much gain.
> 
> EDIT:  I'm finding conflicting reports of the Mu, some sites list 100, other list 16.


 

 I've got a quad of 6n27p that I've used on a balanced EHHA. The tube has a similar Mu to a 6gm8, so no way it's a 100 mU tube. It is a good but not superior alternative to 6gm8's I've tried in the EHHA. I have a quad of Telefunkin and a quad of Sylvania 6gm8's. The 6n27 sounds like most other Russian dual triodes I've listened to, mostly in a Soha II. It has a neutral kind of solid state sound to it without much tube flavor. I would put in a recommendation for the 6n27p for the EHHA except for it is pretty expensive compared to 6gm8 versions. Seems like the availability of 6gm8, especailly as quads, is down lately though.
   
  My experience with the EHHA is that it doesn't do it's best with anything other than the 6gm8 or 6n27p. I never had much enthusiasm for the sound of any 6dj8's or 6H30dr. I found the 6H30 in particular to be a disapointment considering the cost of the tube, the cost of a beefed up heater supply for it, and how impressive they sound in a SOHA II. The EHHA isn't a tube roller at all, it just needs a good pair (quad) of 6gm8's. I didn't get much, if any, changes going from different brands of 6gm8's either.


----------



## keyid

i got a box of hammond lopro 16 VAC @ 3A
  http://parts.digikey.com/1/parts/997967-transformer-lopro-16vct-3a-229d16.html
   
  Can i use two of these? one for each board?


----------



## fishski13

Quote: 





keyid said:


> i got a box of hammond lopro 16 VAC @ 3A
> http://parts.digikey.com/1/parts/997967-transformer-lopro-16vct-3a-229d16.html
> 
> Can i use two of these? one for each board?


 

 Alex talked about this on pg. 16.


----------



## fishski13

i have a couple of Richard's TX and think they're great.  $53 for a single TX compared to $43 for 2 TX from A.L. is compelling for space and chassis layout reasons.  
   
  BMF,
  when you say 60V C.T./200mV, why not just spec a 30-0-30/400mA or a 30V+30V/400mA?  wouldn't this be a little cheaper without the extra secondary leads?
   
  i want to get a BOM put together before buying the TX(s).  right now, the Par-Metals 20-series 12"x12" looks like a nice little pre-fab chassis.


----------



## BoilermakerFan

Quote: 





fishski13 said:


> i have a couple of Richard's TX and think they're great.  $53 for a single TX compared to $43 for 2 TX from A.L. is compelling for space and chassis layout reasons.
> 
> BMF,
> when you say 60V C.T./200mV, why not just spec a 30-0-30/400mA or a 30V+30V/400mA?  wouldn't this be a little cheaper without the extra secondary leads?
> ...


 

 It needs to be a CT trafo.  It might be $5 more for the two windings versus one, but I asked to see.  The two windings make it easy to wire the amp boards too, the leads are long enough for run straight to the amp boards in most cases.


----------



## fishski13

so it's just for ease of wiring, i see.  i'm going to get a quote for a 30V+30V/400mA with 7V heater windings and a single primary.


----------



## FallenAngel

Dual primary has some serious advantages in case the amp ever gets sold to someone.


----------



## cobaltmute

And you can always wire the primaries in parallel. 

 BMF, I know you already have dome most of the work, but do you mind if I ask SumR for a quote on the same but in Canadian dollar? I hate paying the extra charge that the credit card companies tack on, not counting the bad exchanges rates they give you.


----------



## FallenAngel

Yes please.


----------



## jdkJake

Okay, so, whats the trick for posting attachments? It keeps saying I don't have permission.
   
  I have the latest layout, schematic and first release BOM ready to post...


----------



## BoilermakerFan

Quote: 





cobaltmute said:


> And you can always wire the primaries in parallel.
> 
> BMF, I know you already have dome most of the work, but do you mind if I ask SumR for a quote on the same but in Canadian dollar? I hate paying the extra charge that the credit card companies tack on, not counting the bad exchanges rates they give you.


 

 No worries guys.  I only did the work because I'm working with SumR on 4 other amps and two side projects, so I email him pretty regularly.  I was just trying to make it easy on him and you guys. 
   
  As I said earlier, the dual primaries is to cover most of the worldwide voltages so the amp can be sold to most anyone if you guys decide to sell an amp. 
   
  The dual secondaries makes wiring so much cleaner and easier, but if there is a $5 savings and the build budget is that tight, it's a good place to save $5 and put it towards a Nobel pot instead of a RK27 for instance.  I'd personally go with the cheaper rotary power switch and skip the TDR boards to save even more money, but that's just me, everyone has different priorities. 
   
  I need to acquire a few more of my new preferred vintage chassis.  Scored a killer deal on eBay, but there aren't too many of these lower models out their bigger brothers or other models in the same chassis is uber pricey.


----------



## jdkJake

BMF,
   
  For those of us in the USA, did you get a part number? I like it just the way you spec'ed it.


----------



## fishski13

Quote: 





jdkjake said:


> Okay, so, whats the trick for posting attachments? It keeps saying I don't have permission.
> 
> I have the latest layout, schematic and first release BOM ready to post...


 

 can you email it to me?
   
  fishski13 at hotmail dot com
   
  thanks!


----------



## runeight

Here's a link:
   
EHHA Rev A BoM
   
  Edit: And I forgot to thank jdkJake for the huge effort to finish out the BoM. Thanks!!!!


----------



## fishski13

Quote: 





runeight said:


> Here's a link:
> 
> EHHA Rev A BoM


 

 awesome.  i've printed the files and will hopefully have some time tonight at work to look it over.   
   
  thanks a lot Jake!


----------



## jdkJake

You are most welcome. I had a ball!!
   
  Truth be told, Alex did a majority of the work before I got it to finish. Folks, Alex is really putting it out there to make this project a reality! Make no mistake, we are very, very fortunate for his impressive level of support.
   
  So, now the hard part, sourcing the parts. So far, the difficult items have been:
   
  1) WIMA caps. However, I just found that TAW Electronics (authorized dealer) has a ton of them at a good price. 
   
  2) Electrolytics. As usual, up and down on stock. I went with Panasonics (FM's and FC's) from digikey. They spec just as well if not better.
   
  3) LM317/LM337 Regulators. Had to go to Digikey and get the fairchild parts. They seem to have plenty.
   
  4) Vishay 1.21k 1/8W 1% Metal Films. Alex stated you can use 1.3k without issue, which is available.
   
  5) Vishay 121R 1/8 1% Metal Films. Have not found a replacement yet. Alex suggested xicon, I have not checked around yet.
   
  and the weirdest outage:
   
  6)  MC79L15 Regulator. While the MC78L15 is available in spades, the MC79L15 is made out at both Mouser and Digikey. I will hunt them down tomorrow, but, if you have a lead on them, let us know.


----------



## FallenAngel

1) I like to save on shipping if possible (unless I really split parts pretty evenly with great results), go with any cap manufacturer, like Vishay.
  2) Panasonic FM/FC and Nichicon HE/PW are great choices, just double check datasheets for best ESR.
  3) Yep
  4) Lots of 1K21 Vishay/Dale at Mouser, RN55C1211
  5) Lots of 121R Vishay/Dale resistors at Mouser, RN55C1210 with lots more as CMF55121R.
  6) You don't "need" MC79L15, any 79L15 will do and there are tons of those.


----------



## FallenAngel

Of course, as with numerous other projects, both spearheaded and greatly contributed to, a great thanks should be extended to Alex Cavalli.  You are a most generous and involved designer, an inspiration to the community and a role model for how someone who is great in their field should strive to become.  Your work is greatly appreciated.  I look forward to building and enjoying yet another of your amplifier designs.


----------



## FallenAngel

BOM notes:
  1) PSU page, resistor values at Mouser are flipped.
  2) 2R2 output resistor choice: 594-5073NW2R200J (2R2 Metal Film 1W)


----------



## cobaltmute

79L15 regulator option
   
  For the LM317/LM337, you may want to consider the National parts.  The LM337 has an input range to -50V and you can go with the LM317HV to get +50V on the input side, just to give headroom on the voltage input.  Fairchild parts are in stock at Mouser. 
   
  Anyone know of a LM337 in full pack?  There is ST parts for the LM317 (LM317P) and full pack is easy to mount so you don't need washers or mounting kits.


----------



## runeight

Good idea on the HV regs.


----------



## cobaltmute

Sent an email to SumR for pricing on the transformer in CDN $.


----------



## fishski13

my BOM is basically done.  Panny FC 'lytics (50V and 16V), Vishay/BC polyester, UF4004 with 9V heater windings, Kemet C0G, and A.T. heatsinks (http://www.mouser.com/Search/ProductDetail.aspx?R=513102B02500Gvirtualkey53210000virtualkey532-513102B25) for the LM317/337.  i want to wait until i have the boards in hand before i decide to bottom mount the components to allow thermionic protrusion through the top of the chassis - heatsinking now becomes a bit more difficult, requiring a bit more chassis work and negating the need for on-board heatsinks.
   
  i took measurements of the caps' diameter and lead spacing if anybody is interested.
   
  Alex,
  i have a fist full of Q6 and Q7.  is there any benefit to matching considering the Bases are trimmed?


----------



## cobaltmute

Quote: 





cobaltmute said:


> Sent an email to SumR for pricing on the transformer in CDN $.


 

 US $ price = $ CDN Dollar price.
   
   
  Quote: 





> - fully encapsulated and shielded: Cdn $ 75.40/e
> [size=x-small]- just with a core band and mounting hardware: Cdn $ 54/e.[/size]
> 
> Please let me know of any changes, alterations, or other questions.


 
   
  Of course there is HST on that, but that seems to be very good for basically getting dedicated power for each PS and Heater.


----------



## fishski13

i just sent Richard a quote request for a 30-0-30/400mA TX with a 9V/1A heater tap and a single primary, both encapsulated and core band.


----------



## cobaltmute

Just for the record, my request was:
   
  Quote: 





> Basic requirements would be
> -120/240 primary,
> -2 secondaries @ 60V, center-tapped, 200ma
> -2 secondaries @ 7V, 500ma
> ...


----------



## jdkJake

Quote: 





cobaltmute said:


> Just for the record, my request was:


 

 -120/240 primary,
 -2 secondaries @ 60V, center-tapped, 200ma
 -2 secondaries @ 7V, 500ma
  
   
  Did they assign a part number to this configuration?


----------



## jdkJake

Quote: 





fallenangel said:


> BOM notes:
> 1) PSU page, resistor values at Mouser are flipped.
> 2) 2R2 output resistor choice: 594-5073NW2R200J (2R2 Metal Film 1W)


 


 Thanks. I will fix it tonight.


----------



## cobaltmute

Quote: 





jdkjake said:


> -120/240 primary,
> -2 secondaries @ 60V, center-tapped, 200ma
> -2 secondaries @ 7V, 500ma
> 
> ...


 

 I didn't ask him to, but I can...


----------



## runeight

Gents, the quote is back from the fab. For this low volume the boards will be $21 each. Figure less than $5 packaging and shipping CONUS.
   
  Turnaround is 6 business days, which means shipping will be end of next week if I order today. Then two days to get to me and whatever days to get to you.
   
  If the beta guys will kindly give their consent to the order, I'll get it started.


----------



## ujamerstand

Ready to go.


----------



## sachu

lets do this!!


----------



## cobaltmute

Go.
   
  When I should have been working today, I've already got a rough layout for 2xe12,e24, SSR transformer and boards in a 12x12 Par metal case.  Power swtich and knob chosen.


----------



## cobaltmute

Any other suggestions for reliable source for the tube sockets?  The cart at Angela Instruments is not accepting my ship to address.


----------



## johnwmclean

Quote: 





cobaltmute said:


> Any other suggestions for reliable source for the tube sockets?  The cart at Angela Instruments is not accepting my ship to address.


 

 http://www.diyhifisupply.com/node/289
   
  The best I’ve come across are the Moulded-Teflon-Noval-PCB type, although not cheap at $4 a pop - you get what you pay for.


----------



## jamesbobo007

Quote: 





cobaltmute said:


> Any other suggestions for reliable source for the tube sockets?  The cart at Angela Instruments is not accepting my ship to address.


 

 http://www.radiodaze.com/


----------



## stringgz301

go! pm me where i can paypal you the money.


----------



## fishski13

good to go.


----------



## runeight

Gents, thanks for the offers of payment.
   
  I will front the board cost and then after I ship you the boards I'll give you an exact total for boards and shipping.


----------



## fishski13

TX from SumR with single primaries, 30-0-30/400mA with 9V/1A:  core band $43 and encapsulated $59 + $20 shipping to Minnesota.  decisions, decisions....


----------



## cobaltmute

Quote: 





jamesbobo007 said:


> http://www.radiodaze.com/


 

 Maybe its just me, but they don't seem to have a 9pin PCB mount socket...


----------



## cobaltmute

Quote: 





johnwmclean said:


> http://www.diyhifisupply.com/node/289
> 
> The best I’ve come across are the Moulded-Teflon-Noval-PCB type, although not cheap at $4 a pop - you get what you pay for.


 

 Cheaper than the ones I was considering:
http://angela.com/tubesocketninepinpcmountpremiumceramicsilver.aspx
   
  Thanks.


----------



## fishski13

Quote: 





cobaltmute said:


> Maybe its just me, but they don't seem to have a 9pin PCB mount socket...


 

 just call them, i got my tube sockets from them.  Radiodaze is an excellent vendor.


----------



## pabbi1

http://www.partsconnexion.com/product6166.html
   
  These are composite, and I like them a lot. I also have the Azuma ceramics, but prefer the teflon.


----------



## BoilermakerFan

Quote: 





fishski13 said:


> so it's just for ease of wiring, i see.  i'm going to get a quote for a 30V+30V/400mA with 7V heater windings and a single primary.


 

 Single 400mA secondary is only $2 cheaper for each trafo, so $51 instead of $53 for the open and $72 for the S&FE unit.  I'd spring for the dual secondaries...


----------



## johnwmclean

Quote: 





cobaltmute said:


> Cheaper than the ones I was considering:
> http://angela.com/tubesocketninepinpcmountpremiumceramicsilver.aspx
> 
> Thanks.


 

 Yeah, the middle hole in the original EHHA board would not accommodate those sockets, bloody nice though. 

  
  Quote: 





pabbi1 said:


> http://www.partsconnexion.com/product6166.html
> 
> These are composite, and I like them a lot. I also have the Azuma ceramics, but prefer the teflon.


 

 I really like these, same type but cheaper from here:
   
http://www.diyhifisupply.com/node/289


----------



## BoilermakerFan

Quote: 





jdkjake said:


> BMF,
> 
> For those of us in the USA, did you get a part number? I like it just the way you spec'ed it.


 
  Sorry, missed this until now.  I'll post p/n's when I get them.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> -120/240 primary,
> -2 secondaries @ 60V, center-tapped, 200ma
> -2 secondaries @ 7V, 500ma
> 
> ...


 
  That is the original config I posted, both as open banded, and S&FE.


----------



## BoilermakerFan

Quote: 





fishski13 said:


> TX from SumR with single primaries, 30-0-30/400mA with 9V/1A:  core band $43 and encapsulated $59 + $20 shipping to Minnesota.  decisions, decisions....


 

 Single primary locks you in to N.A. resale only.  Not implying you will be unhappy with the amp, but when you decide to make the jump to a commercial CA amp 
	

	
	
		
		

		
			





, it's nice to be able to have a larger customer base.


----------



## fishski13

Quote: 





boilermakerfan said:


> Single primary locks you in to N.A. resale only.  Not implying you will be unhappy with the amp, but when you decide to make the jump to a commercial CA amp
> 
> 
> 
> ...


 
  i have no interest in selling any of my builds 
	

	
	
		
		

		
		
	


	




.  since i'm trying to keep costs down, i'm going with the A.L. as previously mentioned.  they will throw in a band FOC.  i'm not worried about noise mounted in the back of a 12" deep chassis - i could try vertical mounting as well.
   
  i'm going to plank everything out on a sheet of aluminum before i decide on a pre-fab or DIY chassis.  right now, a 20-series 12"x12"x3" looks like a good buy for a total enclosed amp.  the gold alodine might look kind of cool.


----------



## jdkJake

Quote: 





fallenangel said:


> BOM notes:
> 1) PSU page, resistor values at Mouser are flipped.
> 2) 2R2 output resistor choice: 594-5073NW2R200J (2R2 Metal Film 1W)


 

 FallenAngel, are you recommending the 2R2 as an alternate?


----------



## BoilermakerFan

Quote: 





fishski13 said:


> i have no interest in selling any of my builds
> 
> 
> 
> ...


 
  Don't vertical mount, the EM radiates vertically in a column when the tororid is horizontal, so it will go up and down, but not effect any wiring.  The metal mounting washer or top plate helps minimize the EM field, but's not as effective as the full S&FE.  Just be conscious of where the toroid is in the chassis if you plan to stack a source on top of the amp, or then you would be sending EM into the source and the 3" height potentially isn't enough distance to really eliminate it or keep it inaudible.


----------



## FallenAngel

I'm simply recommending metal film over carbon.  For MOSFETs, output resistors should already be 2R2, similarly for BJTs, recommending to use 10R metal film resistors instead of carbon.
  
  Quote: 





jdkjake said:


> FallenAngel, are you recommending the 2R2 as an alternate?


----------



## jdkJake

These are the cheapest price I have seen. I have NO idea on quality.
   
     http://glass-ware.stores.yahoo.net/aik9pinpcbce.html
  
  Quote: 





cobaltmute said:


> Any other suggestions for reliable source for the tube sockets?  The cart at Angela Instruments is not accepting my ship to address.


----------



## jdkJake

Quote: 





johnwmclean said:


> Yeah, the middle hole in the original EHHA board would not accommodate those sockets, bloody nice though.
> 
> 
> 
> ...


 

 I sprung for the gold Angela sockets. The post is supposed to be removable (or so it says on the site). I will let you know. 
   
  Amazing service. I ordered them like Sunday night and they showed up today.


----------



## jdkJake

Quote: 





fallenangel said:


> I'm simply recommending metal film over carbon.  For MOSFETs, output resistors should already be 2R2, similarly for BJTs, recommending to use 10R metal film resistors instead of carbon.


 

 Do you like their sound better? I ask as I have the KOA carbon in my milletts. I never thought to try metal film as everyone seems to rave about the carbon film.


----------



## jdkJake

Quote: 





cobaltmute said:


> I didn't ask him to, but I can...


 

 Thanks, I just sent them the same specs. I should be good to go.


----------



## fishski13

Quote: 





boilermakerfan said:


> Don't vertical mount, the EM radiates vertically in a column when the tororid is horizontal, so it will go up and down, but not effect any wiring.  The metal mounting washer or top plate helps minimize the EM field, but's not as effective as the full S&FE.  Just be conscious of where the toroid is in the chassis if you plan to stack a source on top of the amp, or then you would be sending EM into the source and the 3" height potentially isn't enough distance to really eliminate it or keep it inaudible.


 

 i know this, but am merely ruminating on potential noise issues that might be solved with trial and error, creating a larger distance between toroids and signals.


----------



## jdkJake

Quote: 





fishski13 said:


> i took measurements of the caps' diameter and lead spacing if anybody is interested.


 
   
  Post them and I will update the BOM.


----------



## fishski13

Quote: 





jdkjake said:


> Post them and I will update the BOM.


 

 i just discovered that the Excel files also had BOMs for the heater and PS boards 
	

	
	
		
		

		
			





.  i built my BOM for these off the schematics and board silkscreen at work last night, wondering if there were extra pages i missed.  looks like you have the diameter dimensions for the caps in the heater and PS boards.
   
  the 1uF polyester caps are approx. 5.5 x 7.7mm, and the .1uF polyester and 10pF mica are 7.7 x 2.7mm.


----------



## studeb

I have been told that i missed the cut off for the beta run
   
  if anyone changes their mind and wants to pass on boards, please PM me.
   
  thanks


----------



## BoilermakerFan

Here's the part numbers for the SumR iron:
   
  [size=x-small]1/  RC0050 051 1  : [size=small]120/240 primary, (2) 60VCT @ 200mA, and (2) 7V @ 500mA. Core Banded.[/size][/size]
  2/[size=x-small]  RC0050 051 8  : [/size][size=small]120/240 primary, (2) 60VCT @ 200mA, and (2) 7V @ 500mA. Encapsulated in box.[/size]
   
  [size=x-small]2/ RC0050 052 1  :  [size=small]120/240 primary, (1) 60VCT @ 400mA, and (2) 7V @ 500mA. Core Banded.[/size][/size]
  [size=x-small]2/ RC0050 052 8  :  [/size][size=small]120/240 primary, (1) 60VCT @ 400mA, and (2) 7V @ 500mA. Encapsulated in box.[/size]


----------



## fishski13

Quote: 





studeb said:


> I have been told that i missed the cut off for the beta run
> 
> if anyone changes their mind and wants to pass on boards, please PM me.
> 
> thanks


 

 i have other unfinished projects on the back-burner - actually more like monkeys on my back.  i initially offered to be on the beta-team to help jump start this project, but then 3 others jumped in as well.  i stayed in because i wanted to make sure the board costs were reduced for all, and also because Alex designs are great and i want this amp in my collection.  since you missed the cut-off, i'm willing to give up my spot/boards.  PM sent.


----------



## keyid

is the EHHA sensitive to hum like b22 and requires encapsulated power supply? [size=medium] [/size]


----------



## runeight

The EHHA I seems to have generally been a quiet amp when using a s22 power supply. The only proto build of the EHHA Rev A exhibits a bit of noise with low Z cans, but it isn't cased and lives in a rats nest of open wiring. So no definitive information there.
   
  I think the beta builders should know this pretty quickly from their new builds.


----------



## cobaltmute

My search skills are defeating me in checking the EHHA I thread - how tall is a populated board?  Trying to figure out the case height I'm going to use.


----------



## ujamerstand

If I remember correctly I had everything at around 2.5" including the tubes and the heatsinks. You could use a 3" case with short standoff I suppose...


----------



## jdkJake

Quote: 





fishski13 said:


> i just discovered that the Excel files also had BOMs for the heater and PS boards
> 
> 
> 
> ...


 
   
  Doh!  Oh well.  
   
  Probably learned a lot more about the design that way.


----------



## jdkJake

Quote: 





cobaltmute said:


> My search skills are defeating me in checking the EHHA I thread - how tall is a populated board?  Trying to figure out the case height I'm going to use.


 

 All of the heatsinks specified on the BOM are 2". So, if you went with that as your guide, then you only need to account for the tubes and the transformer.
   
  I am leaning for a 3" height. I still like the "tube out the top" look.


----------



## jdkJake

Another source for tube sockets.
   
      http://www.rfparts.com/sockets.html


----------



## cobaltmute

Quote: 





jdkjake said:


> All of the heatsinks specified on the BOM are 2". So, if you went with that as your guide, then you only need to account for the tubes and the transformer.
> 
> I am leaning for a 3" height. I still like the "tube out the top" look.


 
   
  I want to do 3", but fully in the box.  10mm from the bottom of the case to the top of the board with the standoffs I have.  50mm tube height from the bottom of the pins to the top of the glass. That give maybe 10mm for the socket to raise the bottom of the tube and give 5mm clearance.
   
  I think I may have to wait until after I get the parts to order the case...


----------



## fishski13

Quote: 





cobaltmute said:


> I want to do 3", but fully in the box.  10mm from the bottom of the case to the top of the board with the standoffs I have.  50mm tube height from the bottom of the pins to the top of the glass. That give maybe 10mm for the socket to raise the bottom of the tube and give 5mm clearance.
> 
> I think I may have to wait until after I get the parts to order the case...


 
   
  the measurements with my tube sockets in my Bijou and 1/4" stand-offs should yield about 8mm clearance, assuming a true internal chassis height of 3'.  the Par-Metal 20-series is 2.94", yielding about 6mm clearance.  i have no idea how hot these boards will get, but i'm now thinking a 4" height in the 20-series would be a safer bet considering the placement of the vents.


----------



## cobaltmute

Thanks, that info is very useful.
   
  I have a drill and the case will end up with some new vents...


----------



## jdkJake

So, I don't usually do this, but, I feel compelled at this point.
   
  I wanted to do a build that was as reflective as possible of the BOM. So, when I could not get the WIMA caps from Mouser, I went to TAW Electronics as they are an authorized WIMA dealer.
   
  What happened next surprised and delighted me. I got an email from Laura at TAW who told me that because my order was so small (two builds worth of caps) could she switch to US Mail instead of UPS? Note, this was Wednesday. I said sure and lo and behold, they showed up today. Total cost of shipping? $0.91USD.
   
  That my friends, is AWESOME customer service!
   
  YMMV.
   
  jk


----------



## fishski13

a rough sketch of my lay-out on TurboCAD.  chassis 12"x12", TXs, boards and pot are proper scale - i roughly guesstimated the others components. i tried separating each board into 3 pieces and played around with the lay-out as well, but so far i like this the best.  i may even experiment with vertical mounting the e12 right behind the TRS jack to allow the boards to be squeezed in a little closer, allowing more wiring room, especially for the AC/TXs and switches.


----------



## fishski13

here's another i was considering as well.


----------



## qusp

damn, I take my eye off the thread for a week and look what happens. I miss out on free beta boards


----------



## fishski13

member studeb will be replacing me on the prototyping team.  i'm still interested in building this amp once the production boards are ready, and hopefully will have my other projects finished by then.


----------



## cobaltmute

Quote: 





qusp said:


> damn, I take my eye off the thread for a week and look what happens. I miss out on free beta boards


 
   
  No free boards.
  
  Quote: 





runeight said:


> Gents, the quote is back from the fab. For this low volume the boards will be $21 each. Figure less than $5 packaging and shipping CONUS.


----------



## TimJo

Quote: 





jdkjake said:


> So, I don't usually do this, but, I feel compelled at this point.
> 
> I wanted to do a build that was as reflective as possible of the BOM. So, when I could not get the WIMA caps from Mouser, I went to TAW Electronics as they are an authorized WIMA dealer.
> 
> ...


 

 Yes, when I worked with Laura on getting caps for the first run of eXStatA boards, she was quite helpful and provided excellent service (not to mention a tremendous discount since we were doing a team buy).


----------



## runeight

You boys are so quiet. 
	

	
	
		
		

		
			




   
  Those of you who are going to beta could start sending me addresses. Boards might be here by week's end (although it will be a close call) whether Fri or Tue. Please send to alex@cavalliaudio.com. No PMs please.


----------



## jdkJake

Busy getting parts lined up (done, everything is on order or has been received). I am also spending a lot of time on casing options. There are SO many ways one could go.

 Besides the fact I had to rework my MOSFET-MAX panels, install the grubdac I finished a few weeks ago, finish the debug of the gamma2 I was building when this thread started, well, let's say I needed to clear off the bench.

 Oh yeah, and that pesky work thing. 

 Address on it's way. Getting excited!! Should be great!!


----------



## cobaltmute

I've been working like mad for the last 5 days.  thought I'd have a chance to get my BOM together, but didn't have a chance.
   
  I am working on getting the rest of the parts though.  Looking to be a tight fit for what I want in a 12x12 Par-Metal.
   
  Address sent.


----------



## stringgz301

Up early ordering parts.  A few questions:
   
  1 - if I go with custom iron from SumR with the heater at 7V I should use the UF4002 diodes (and not the 1N5822 ones) correct?
  2 - they were out of the ON Semi 79L15 so I subbed this one from STMicro .  I assume there is no issue mixing positive and negative regs from different vendors?
   
  Looking forward to starting this build.


----------



## cobaltmute

the STMicro part you linked to is a LM317, or at least that is what I get when I click the link.  Any of the 79L15 parts will work, no worries about mixing vendors.
   
  EDIT:  You should use 1N5822 diodes - they are lower voltage drop and so that you'll get proper regulation.    The UF4002 are chosen for 9V transformers to get a higher voltage drop to get the unregulated voltage closer to the regulated voltage for less heat in the regulator.


----------



## jdkJake

Quote: 





stringgz301 said:


> 2 - they were out of the ON Semi 79L15 so I subbed this one from STMicro .  I assume there is no issue mixing positive and negative regs from different vendors?


 
   
  As cobaltmute stated, any of the 79L15 will work. I ended up going with fairchild parts for both the 79L15 and 78L15:
   
     http://www.mouser.com/_/?Keyword=79l15
     http://www.mouser.com/_/?Keyword=78l15


----------



## runeight

Gents, I don't have any shipment info so boards haven't gone out yet.
   
  In the meantime, I've been working on schematics for the website. This amp's OL and CL gains work exactly like the EHHA I. You can refer to the tweaks pages on the EHHA portion of the CA website for information about this.
   
  Some of you may wish to socket resistors in order to play with these two gains. To do this, you should socket:
   
  R13, R14 for the OL gain
  R10, R11 for the CL gain
   
  The values for these resistors shown in the tables on the EHHA website should be very close.


----------



## studeb

What are the "tried and true" gain settings that have been used for the mosfet EHHA?
   
   
  Quote: 





runeight said:


> Gents, I don't have any shipment info so boards haven't gone out yet.


 
  Alex, i emailed you again.
   
  Please let me know if it not getting there.
   
  Stuart


----------



## runeight

Gents, I have addresses from:
   
  jdkJake
  ujamerstand
  stringg301
  cobaltblue
  studeb
   
  I'll let you know when the boards ship to me.


----------



## BoilermakerFan

Quote: 





runeight said:


> Gents, I don't have any shipment info so boards haven't gone out yet.
> 
> In the meantime, I've been working on schematics for the website. This amp's OL and CL gains work exactly like the EHHA I. You can refer to the tweaks pages on the EHHA portion of the CA website for information about this.
> 
> ...


 

 Sweet!  Thanks AC.  This is important when rolling the outputs.


----------



## fishski13

as far as SIP sockets go, i've stripped out some of the cheaper stamped ones with the thicker leaded Vishay RN resistors.  these ones are machined brass and tougher: http://www.mouser.com/ProductDetail/Aries/40-0518-10/?qs=sGAEpiMZZMs%2fSh%2fkjph1tvt1%2fmEPT%2fXoWYvA1DYqDiA%3d


----------



## runeight

Gents, I have started the EHHA Rev A section on CA. Not enough to help you build the amps yet, but a start.


----------



## jdkJake

Quote: 





runeight said:


> Gents, I have started the EHHA Rev A section on CA. Not enough to help you build the amps yet, but a start.


 

 I think a quick summary of the important test points is the most critical at this point. What to measure and what to expect.
   
  IMHO, the schematic and BOM will get us through the actual build process.


----------



## runeight

Have added Boards, Assembly, and Setup sections. They probably need editing and scrutiny.


----------



## runeight

And now I've finished with the PS and Heater schematics. Nothing special with these, but now you have them.
   
  Boards did not even ship this week. I am surprised. I'll call the fab on Tue to find out the status.


----------



## ujamerstand

I've skimmed over the sections and everything looks good so far. Well, maybe step 8 "Figure out what's wrong" in the setup section is a bit vague... Didn't catch anything serious though.
   
  Anyways, taking a break from the exstata, and drew some stuff:

               "Amplifier for the Space Age Cowboy"


----------



## runeight

Right out of the movie City Slickers.


----------



## pabbi1

No, more like Roy Rogers, a la Arby's:
   
  Just sayin that may be a wee bit @ infringement.


----------



## BoilermakerFan

Quote: 





pabbi1 said:


> No, more like Roy Rogers, a la Arby's:
> 
> Just sayin that may be a wee bit @ infringement.


 
   
  Thanks Al, now I'm craving a roast beef sandwich and a Jamocha shake at quarter till 10:00pm on a Sunday nioght.


----------



## jdkJake

Pretty soon someone is going to start talking cream soda and that will be all she wrote...


----------



## jdkJake

"And the waiting is the hardest part..."
   
   

   
   
  Just need a transformer.
   
  Oh yeah, and a couple of boards.


----------



## runeight




----------



## ujamerstand

Correction needed on the BOM. Part numbers for C1,C2 (2200uf 50V) have been swapped against C4,C5,C6 and C7(100uf 50V) under the PS tab. Both of which are currently on order. Replacements with the same lead spacing are: 647-UVR1H101MPD1TD and 647-UVR1H222MRD6.
   
  Also, the order for 2 three position terminal block under the amp tab should be split to 1 four position terminal block and 1 three position terminal block to reflect the changes to the board. Part Number 1729144 could be used here, otherwise, buy another 2 two position terminal blocks


----------



## sachu

I need to dig through my parts bin..but should have most of the parts needed to stuff the boards. Might just stick with the usual Avel toroid i use in all my EHHA builds.


----------



## jdkJake

ujamerstand said:


> Correction needed on the BOM. Part numbers for C1,C2 (2200uf 50V) have been swapped against C4,C5,C6 and C7(100uf 50V) under the PS tab. Both of which are currently on order. Replacements with the same lead spacing are: 647-UVR1H101MPD1TD and 647-UVR1H222MRD6.
> 
> 
> 
> ...







 Okay, thanks. I will update tonight and get a new revision to Alex for posting.


----------



## runeight

Boards should ship tonight which means I get them on Thu.


----------



## studeb

Where can one source the 6GM8 tubes?
   
  i am not having much luck locally or on the net


----------



## ujamerstand

http://www.upscaleaudio.com/Valvo-6GM8ECC86_p_89.html
   
http://www.tubeman.com/item49.htm
   
http://www.tubedepot.com/nos-6gm8.html
   
  Alternatively, see if jeff @ glassjaraudio would like to share his stash. Otherwise, I've got a pair amperex that I'm not using anymore. Let me know if you want them.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> Pretty soon someone is going to start talking cream soda and that will be all she wrote...


 

 Cream Soda, eh?
   
  Here's my favorite Cream Soda:
   

   
  http://www.sprecherbrewery.com/soda.php


----------



## runeight

BoM is updated. Thanks ujamerstand.


----------



## jdkJake

Quote: 





studeb said:


> Where can one source the 6GM8 tubes?
> 
> i am not having much luck locally or on the net


 
   
  Can always count on Dale and Roy:
   
     http://www.vacuumtubes.net/
   
  Overall, they are hard to find at a reasonable price. So, don't be too shocked to see what they are going for now days.


----------



## cobaltmute

I decided to go with the 6N27P.  Have four of them on the way to me.


----------



## jdkJake

Testing/Matching MOSFETS tonight...
   
   

   
  Next up is the transistors...


----------



## runeight

Boards have shipped.


----------



## fishski13

jake,
  that's a cool MOSFET matching set-up.


----------



## jdkJake

cobaltmute said:


> I decided to go with the 6N27P.  Have four of them on the way to me.







 Those are mil-spec versions correct? Or at least Russian mil-spec.

 Should be interesting to see how well matched the sections are across each tube. Do you have a way of testing them once they arrive?


----------



## jdkJake

fishski13 said:


> jake,
> 
> 
> that's a cool MOSFET matching set-up.







 Thanks! I was getting frustrated with the alligator clip and wire version I was using previously. This works much faster. Pretty much overkill for the task, but, this is head-fi after all!


----------



## cobaltmute

Quote: 





jdkjake said:


> Those are mil-spec versions correct? Or at least Russian mil-spec.
> 
> Should be interesting to see how well matched the sections are across each tube. Do you have a way of testing them once they arrive?


 
   
  Nope, no way of testing them.   Price was good though.


----------



## BoilermakerFan

Quote: 





cobaltmute said:


> I decided to go with the 6N27P.  Have four of them on the way to me.


 

 Regular or EV versions?
   
  Edit:  Nevermind, thought it was the 6n23P...


----------



## stringgz301

I remember reading earlier in this thread that in this updated design device matching was not as important. That being said, which devices should be matched?


----------



## runeight

MHO is that device matching is not needed. The Toshiba transistors should be selected in the same hfe class though.
   
  If I were matching I would match two things.
   
  1. The O/P mosfets,
  2. The mu of the two triode sections or even all four sections in both channels.
   
   But if I were building the amp I would not make the effort to do this. I do understand that others have different diy preferences.


----------



## luvdunhill

If I remember correctly, these MOSFETs (IRF550/IRF9540) will not make great complementary pairs... I bet you'll have a ~0.5V difference in Vgs between the two types. If you have a distortion analyzer, you could probably play with R22, R23 to find a null point... probably not worth the effort as Alex said though.


----------



## sachu

Indeed, matching of the triode sections of the tube might actually be more beneficial, even though you can balance these out (so far as they are not too far away from each other). 
   
  Got my Toshiba BJTs at the ready for the output devices.


----------



## luvdunhill

yup, however if you're not matching either at the voltage/current/temperature parameters of the circuit, it might be wasted effort that could be spent in building another one of Alex's designs


----------



## runeight

Gents, please don't use the BoM that I just posted. I used an older version and it is very wrong.
   
  New one up soon.


----------



## runeight

New BoM is posted. I believe this one is correct. Please let me know.


----------



## BoilermakerFan

Quote: 





luvdunhill said:


> yup, however if you're not matching either at the voltage/current/temperature parameters of the circuit, it might be wasted effort that could be spent in building another one of Alex's designs


 

 Muaaahaaahahaaa!  
	

	
	
		
		

		
		
	


	



   
  But on the DIY front for dynamic cans, the EHHA is the top of the heap with the possible exception of a well executed Bijou if you prefer it's sound. There's more to be eeked out of the EHHA WRT to output sand rolling too, then you have to tweak the NFB.  I won't be matching my devices, but I will be rolling them.


----------



## runeight

No boards today. Looks like the deluge has slowed down the fedex deliveries. Oh well, no one could have gotten a board before the weekend anyway. Maybe tomorrow.


----------



## runeight

Wrong again. Even thought the tracking said that the package was still at the facility, the boards have arrived. Very clever boards gents.


----------



## jdkJake

luvdunhill said:


> yup, however if you're not matching either at the voltage/current/temperature parameters of the circuit, it might be wasted effort that could be spent in building another one of Alex's designs









 Ouch!



 BTW, you are right, there is up to a 1/2 volt difference between the two parts. At least at the sub-optimum level I tested them at.


----------



## ujamerstand

Quote: 





runeight said:


> MHO is that device matching is not needed. The Toshiba transistors should be selected in the same hfe class though.


 
  Doh. The sources of my 2sa1145s are different, some from bdent, some from mouser. In fact, they are visibly different. -_-\\ I should probably get a test rig going to check their hfe value before I populate them into the boards...


----------



## jdkJake

ujamerstand said:


> Doh. The sources of my 2sa1145s are different, some from bdent, some from mouser. In fact, they are visibly different. -_-\\ I should probably get a test rig going to check their hfe value before I populate them into the boards...







 Toshiba uses two ratings, O and Y. The O rating is the lower of the two (80 to 160 hfe) with the Y being the higher (120 to 240). There is the potential for overlap, but, I think Alex is trying to say that as long as you stay within the same rating class you are fine.


----------



## luvdunhill

Quote: 





ujamerstand said:


> Doh. The sources of my 2sa1145s are different, some from bdent, some from mouser. In fact, they are visibly different. -_-\\ I should probably get a test rig going to check their hfe value before I populate them into the boards...


 

 even if they are visible different, that's okay as long as the hfe class is the same. There are two versions of these, one with etched identifiers on the case, and one with whiteish-ink-printed labels. The etched ones are the later devices.


----------



## ujamerstand

That's a relief. I was afraid that I might have to another run to mouser for more parts. (since I just made one yesterday.) the "O" or "Y" lettering is followed by three dots then a digit and a letter, is this correct? Any ideas on the significance of the letterings after the three dots? Batch identification?


----------



## luvdunhill

the dots (or line in later versions) distinguishes if the devices is RoHS compliant. The letter is indeed the lot number, which is a factory, year, batch encoded value.


----------



## runeight

Quote: 





ujamerstand said:


> That's a relief. I was afraid that I might have to another run to mouser for more parts. (since I just made one yesterday.) the "O" or "Y" lettering is followed by three dots then a digit and a letter, is this correct? Any ideas on the significance of the letterings after the three dots? Batch identification?


 


 But, you did get either all O or all Y?


----------



## ujamerstand

Yes. All of the devices I have on my hands are O devices. I've also received most the parts for rev.A today. Just waiting for sumr to ship my transformer and I'll be ready to start building.


----------



## runeight

Boards went out today.


----------



## jdkJake

runeight said:


> Boards went out today.







 That's great news Alex.

 Looking forward to it.


----------



## runeight

Beta builders, I have one small request of you all. jdkJake has agreed to build one beta board as quickly as possible. Although there are two working proto boards, there are enough changes to the new boards that I would like to have one verification before the rest of you build.
   
  Would you all consider waiting a bit for jdk to make this build?


----------



## sachu

That sounds fine by me.


----------



## ujamerstand

That's fine.  Don't forget to let us know the cost of the boards and shipping!


----------



## jdkJake

I will do my best to turn around a build quickly.
   
  Just one FYI, I still have not received my transformer. I placed the order back on the 26th of August and have not received a ship date yet. I will email Richard and see where things stand. So, that might throw a wrinkle into the plan.
   
  Other than that, I am good to go.


----------



## studeb

Quote: 





runeight said:


> Beta builders, I have one small request of you all. Would you all consider waiting a bit for jdk to make this build?


 


 i can wait. it may be one of the few things i am good at.


----------



## stringgz301

No problem.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> I will do my best to turn around a build quickly.
> 
> Just one FYI, I still have not received my transformer. I placed the order back on the 26th of August and have not received a ship date yet. I will email Richard and see where things stand. So, that might throw a wrinkle into the plan.
> 
> Other than that, I am good to go.


 

 Let Richard know this is for a Cavalli Audio DIY build too.  He's been great at getting iron for me quickly for Cavalli Audio prototypes.  If you went with shielded and encapsulated, there is a 3-4 day longer lead-time while the epoxy sets.


----------



## jdkJake

Talked with Richard yesterday. They have to finish the secondaries and perform the encapsulation. He expects to ship next week. Things will probably lne up just fine.

 BTW, I went for the fully shielded, fully encapsulated version.


----------



## runeight

Gents, what are the specs on these fancy transformers that you are buying?


----------



## ujamerstand

I bought the "RC0050 051 8" for about $75 CAD. After shipping and tax it's about 100 dollars.
  Quote: 





boilermakerfan said:


> Here's the part numbers for the SumR iron:
> 
> [size=x-small]1/  RC0050 051 1  : [size=small]120/240 primary, (2) 60VCT @ 200mA, and (2) 7V @ 500mA. Core Banded.[/size][/size]
> 2/[size=x-small]  RC0050 051 8  : [/size][size=small]120/240 primary, (2) 60VCT @ 200mA, and (2) 7V @ 500mA. Encapsulated in box.[/size]
> ...


----------



## jdkJake

ujamerstand said:


> I bought the "RC0050 051 8"




<

 I never got a part number, but it appears to be the same.

 Specifically, I ordered:

 -120/240 primary,
 -2 secondaries @ 60V, center-tapped, 200ma
 -2 secondaries @ 7V, 500ma
 -fully encapsulated and shielded


----------



## runeight

Boys, the schematics were wrong on the website. R10 and R11 were swapped. They are correct on the board and BoM.


----------



## jdkJake

Quote: 





runeight said:


> Boys, the schematics were wrong on the website. R10 and R11 were swapped. They are correct on the board and BoM.


 

 It appears that the Mod 9 version is okay. Was it just the version posted on the Web Site?


----------



## runeight

Yes, I posted new versions on the website before the above message.


----------



## studeb

waiting............


----------



## johnwmclean

My gosh those black boards are sexy...


----------



## sachu

*drool*..I haven't received my boards yet. Can't wait.


----------



## sachu

I got a mouser project finished up for the EHHA Rev A BJT version. 
   
  If someone wants to go over the BOM and let me know if anything is missing, it would be appreciated. 
  It is missing the heater transformer for sure which i will add later tomorrow.
   
  I will also substitute parts for those items that are back ordered as well in the next update.
   
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=659bae8d48


----------



## jdkJake

I was wondering who would get the first one.

 Mine have not arrived yet.


----------



## stringgz301

Got my boards yesterday.  Now just need to wait for Jake 
	

	
	
		
		

		
			





.
   
  One suggestion for the next board run: provide an indication of LED orientation on the board.  It's clear from the schematic what it should be but I don't see anything on the board itself (except for the arcs on one side being ever so slightly shorter).
   
  Can't wait to get going.


----------



## runeight

Ah, nice that there is a picture posted. You guys have already figured this out, but the big hole in the rail supply section is there so you can turn the terminal block around so that its inlets face into the board and so that you can run the 30V wires underneath and through the hole to the terminal block.
   
  Did I already mention this??


----------



## TimJo

Those do look nice, and so compact for an all-in-one ps/amp.
   
  Just biding my time till they are tested and the production run happens.
   




   
   
  I think it'll make a fine amp for my HE-5LE's...


----------



## sachu

Quote: 





runeight said:


> Ah, nice that there is a picture posted. You guys have already figured this out, but the big hole in the rail supply section is there so you can turn the terminal block around so that its inlets face into the board and so that you can run the 30V wires underneath and through the hole to the terminal block.
> 
> Did I already mention this??


 
  Nice feature Alex.


----------



## stixx

Away for 3 weeks, 350+ more posts... this thread is moving fast!
   
  Awesome work so far and really "sexy" looking boards...


----------



## studeb

Quote: 





sachu said:


> I got a mouser project finished up for the EHHA Rev A BJT version.
> 
> If someone wants to go over the BOM and let me know if anything is missing, it would be appreciated.
> It is missing the heater transformer for sure which i will add later tomorrow.
> ...


 
   
  you have 9 of the 0.1uF Wima, could be 2
  you have 7 of the 1.0uF Wima, could be 9
  you have 5 2sc2705 could be 4
  do you have enough 2k94 for the LEDs i see 2


----------



## jdkJake

Let the Dance Begin...


----------



## ujamerstand

I hope you're not pulling an all-nighter on this...


----------



## sachu

heh..its a 3 hour jobby at most with concentration and having everything at the ready. Then again stuffing is only the beginning. Good luck buddy.


----------



## jdkJake

I had to work late tonight (and get up early tomorrow), so, I did not get as far as I wanted to, but, it is a good start:
   

   

   
  I have to work late again tomorrow, but I will definitely mount the small signal transistors. Those usually take the most time as I have a deliberate technique for soldering whereas I heatsink each part. Slow, but works every time. Never lost one that way. 
   
  Ideally I will finish on Thursday. The planets lined up and I have Friday off, so, I will wire it up and begin testing Friday morning. Should have some preliminary results Friday evening.
   
  More to come....


----------



## johnwmclean

The pressure gets to jdkJake...
   

   
  Darn these small signal transistors


----------



## ujamerstand

I always spend at least an hour trying to align these damn things. -_-


----------



## stringgz301

Alex - are you going to post an updated wiring diagram?  I particularly want to confirm star-ground wiring.


----------



## runeight

You mean my excellent, super detailed, and, no doubt, very clear wiring description is not good enough? 
	

	
	
		
		

		
			




   
  I should be able to post one later tonight. But real men don't need wiring diagrams.


----------



## stringgz301

Ouch!  But real men end up making 5 orders from Mouser to replace fried parts.


----------



## nikongod

Quote: 





runeight said:


> I should be able to post one later tonight. But real men don't need wiring diagrams.


 

 or PCB's


----------



## cobaltmute

A real man builds point to point, without schematic or tools, cold welding the joints with their bare hands.


----------



## runeight

That's right. Back in the old days ...


----------



## runeight

Wiring diagram is posted on the Setup page. Please let me know if it doesn't make sense. Normally I don't use colors on these, but this one has so many overlaps colors were the only way to tease apart the wires.


----------



## jdkJake

Build completed, on to verification and test...
   

   

   
   
  I got home a bit earlier than I expected tonight. I finished up the build. Tomorrow I will check my work, clean it up and get ready for the power tests. Build went fine, nothing unexpected and all the parts fit without issue. The black solder mask is a trip. Looks great, but reflects no light. Kind of screws with the eyes a bit when you solder, especially if you are used to various shades of green. For those who put down the cash, the Angela sockets fit like a dream (with or without the hollow center post). I took mine out, but, you could have easily left it in as Alex has a perfectly sized hole underneath. Nice.
   
  Here are a couple of shots before the cooling towers went up (they really dwarf the board):
   
   

   

   

   
  Another early day tomorrow, so, that's it for now. After tomorrow, I can focus full time on the board checkout.
   
  Looking forward to it.


----------



## sachu

an..that is one fine looking board. Can't wait to get my hands on them. Ordered a par-metal case for my build.


----------



## runeight

I've also added an alternate wiring scheme if you have hum/buzz problems.


----------



## studeb

and?????


----------



## jdkJake

studeb said:


> and?????







 and the custom sumr transformer did not make it in time for today.

 HOWEVER, Plan B just showed up on my doorstep....


----------



## jdkJake




----------



## jdkJake

Alex: Please update the schematic to reverse the polarity of the LED on the -30 rail.  Thanks.


----------



## jdkJake




----------



## ujamerstand

What's the reading for for the second last image? DC offset?


----------



## studeb

output bias
  220mV for Mosfet
  1V for BJT
   
  Forgot to say, looks great!


----------



## studeb

How much heat is generated idling?
  And what heater t/f  are you using?


----------



## runeight

Quote: 





jdkjake said:


> Alex: Please update the schematic to reverse the polarity of the LED on the -30 rail.  Thanks.


 

 I think the schematic is ok, but the lack of + sign on the board is definitely a problem. I'll fix this if we have another board run.
   
  So, your measurements mean that all the DC voltages came up properly?


----------



## runeight

Oh, I see what you mean. That LED shouldn't even be there. There is just one LED that goes under the tube but it uses both resistors. I'll fix.


----------



## jdkJake




----------



## jdkJake

Quote: 





runeight said:


> I think the schematic is ok, but the lack of + sign on the board is definitely a problem. I'll fix this if we have another board run.
> 
> So, your measurements mean that all the DC voltages came up properly?


 
   
  Yes.


----------



## jdkJake

Quote: 





runeight said:


> Oh, I see what you mean. That LED shouldn't even be there. There is just one LED that goes under the tube but it uses both resistors. I'll fix.


 

 No, I mean the PS LED for the -30V rail.
   
  The cathode/anode orientation for the schematic posted on the web site needs to be reversed. Otherwise, it does not light up. I initially installed it from the schematic.
   
  Of course, the inclusion of polarity markings on the board will go along way.


----------



## studeb

Quote: 





runeight said:


> I think the schematic is ok, but the lack of + sign on the board is definitely a problem. I'll fix this if we have another board run.


 
   
  Is the flat side of the cathode not on the board?


----------



## jdkJake

_*"Greetings in the name of His Majesty, Jah!, Rastafari!"*_
   
  We be jammin'


----------



## sachu

wow..nicely done JDK..excellent turn around time.


----------



## runeight

Hmmm. I think it is in the right orientation on the rails PS schematic. Is this the one you mean? Anode should go to ground and cathode to the -30V rail. Yes? No?


----------



## studeb

Looks fantastic, well done!!!!


----------



## runeight

Holy cow, wait a few minutes to make a post and the finished amp appears.
   
  No problems?
   
  It is a nice looking set of boards. 
	

	
	
		
		

		
			




   
  Thanks for the very fast turn.
   
  If your amp is stable for a day, then I think everyone else can go ahead and build.


----------



## jdkJake

Okay, looks like we have a baseline.
   
  When the sumr transformer did not look like it would make it in time, I placed an order for the Antek transformers colbaltMute so graciously found as a backup. That turned out to be a good idea, otherwise, we would be waiting. The AN-0107 is being used for the heater and the AN-0232 is being used for the +/- 30V rails. It is early, but they appear to work just fine. Both power supplies appear to be holding in regulation just fine. I have had very little heater supply drift once the tubes warm up properly. The +/-30V rails appears just as stable, but, it is early. biasing of the MOSFET's went fine. As expected, they drift with temperature, but, hold fine once everything is up at temp.
   
  I ended up using the "Two Channel Alternate Wiring" hook up from the site. With the first wiring, I had a slight buzz. That cleared up with the alternate wiring. Realize, the test platform is not ideal for noise containment, but, it appears to be fine. No buzz or hum, just a slight hiss at full-open with a little bit of background noise. I suspect, a real case and careful re-orientation of the wiring (like, moving star ground from the same terminal strip as the power) should clean that up just fine. Nothing that should not clear up with a better installation.
   
  At this point, I think it is safe to proceed with the rest of the beta builds. I found nothing in the build that was a real issue beyond the LED orientation for the -30V rail. That was the only component I had to pull and replace. Everything else came up first shot. No issues.
   
  I need to take a break for food. I am starving.   After dinner, I will measure the DC offset at power on, see how fast it settles and also take some temperature measurements on each of the heatsinks.
   
_Oh yeah, sounds great!   
	

	
	
		
		

		
		
	


	


_


----------



## jdkJake

Quote: 





ujamerstand said:


> What's the reading for for the second last image? DC offset?


 

 Yes. Followed by MOSFET Bias.


----------



## jdkJake

Quote: 





runeight said:


> Oh, I see what you mean. That LED shouldn't even be there. There is just one LED that goes under the tube but it uses both resistors. I'll fix.


 

 That is true as well.


----------



## cobaltmute

The -30V rail LED orientation is correct on the website.  Current flows from the most positive end to the negative end of the LED.  So from the + rail to ground or ground to the negative rail.


----------



## cobaltmute

I'll be waiting longer to build as the boards must be in postal system somewhere...


----------



## jdkJake

Two more, then food:
   

   

   
  Okay, enough with the vanity shots.


----------



## stringgz301

So that's what the flat black surface is for in the kitchen.  I always wondered.
   
  Nice job.


----------



## ujamerstand

Quote: 





cobaltmute said:


> I'll be waiting longer to build as the boards must be in postal system somewhere...


 
  I'm hoping that it'll show up no later than next week.


----------



## jdkJake

stringgz301 said:


> So that's what the flat black surface is for in the kitchen.  I always wondered.
> 
> 
> 
> ...







 That is our new stove top. Since it is so freakin' hot, my perfectly good workbench in the garage goes unused. The stove top works well l as it cannot be damaged by heat or solder and the exhaust hood vents solder fumes. It actually works quite well, and the inside of the house is wonderful, non-humid 77degrees Fahrenheit.


----------



## jdkJake

So, not sure if you can tell or not from the photos. The smaller of the two boards, the one the boards are actually mounted on is 12inches by 12inches.

 That should give you some idea of scale. It is also the exact size of the Par metal case I am considering.


----------



## jdkJake

runeight said:


> Hmmm. I think it is in the right orientation on the rails PS schematic. Is this the one you mean? Anode should go to ground and cathode to the -30V rail. Yes? No?







 The schematic is right. I read it wrong. Sorry for the fire drill. User error on my part.


----------



## sachu

Nice..i just ordered a 12x12x4 par metal enclosure for this amp.


----------



## runeight

So, Jeff, how does the amp sound after a few hours? Was it worth the build?


----------



## jdkJake

runeight said:


> So, Jeff, how does the amp sound after a few hours? Was it worth the build?







 Shhh.... I am still listening, one of my favorite songs just came on....


----------



## funch

Quote: 





jdkjake said:


> Shhh.... I am still listening, one of my favorite songs just came on....


 


      Now that's funny right there.  BTW, what's the board's dimensions?


----------



## jdkJake

funch said:


> Now that's funny right there.  BTW, what's the board's dimensions?







 About 4 and 1/4 inches by about 5 and 7/8 inches. The actual measurements are posted somewhere in this thread, but, that should give you a general idea.


----------



## runeight

Board is 110mm W x 150 mm L
   
  Edit: change to 110mm


----------



## jdkJake

Okay, seems to be warmed up again. I had to shut it down to use the stove to make dinner. 

 In any case, the heater voltage and MOSFET bias is steady as a rock. No issues there. As for the heatsinks, keep in mind these are 2 inch heatsinks and room temp is 77 degrees F (25C). Measure is at the top center of each heatsink:

 MOSFETS: ~45 to 47C
 PS: ~40 to 42C
 Heater PS: ~35C


----------



## cobaltmute

Quote: 





jdkjake said:


> Okay, seems to be warmed up again. I had to shut it down to use the stove to make dinner.
> 
> In any case, the heater voltage and MOSFET bias is steady as a rock. No issues there. As for the heatsinks, keep in mind these are 2 inch heatsinks and room temp is 77 degrees F (25C). Measure is at the top center of each heatsink:
> 
> ...


 

 Seems not too bad - especially for the PS considering that is a 32V transformer as opposed to a 30V.
   
  Current outside temp is 11C.  I just need to open the window to keep it cold.


----------



## jdkJake

Lucky dog. We have the AC cranked to get it down to 25C. Brutal summer this year after a most cold winter (at least for Florida).

 The power supply is barely breaking a sweat. The torrid itself is pretty warm. The flat washer on the center screw that holds down the top plate is running about 51C.


----------



## jdkJake

Time to call it a night. I didn't get to measure the DC offset as I said I would. As they say, tomorrow is another day. I will do it then and post the results.
   
  Thanks to all for the kind comments regarding the build. It was a fun build. I really had a blast!
   
  Couple of parting shots (as I cannot help myself 
	

	
	
		
		

		
			





)...


----------



## fishski13

Jake,
  looks great!


----------



## stixx

Yes, excellent work...
   
  The measured temp on the toroid hold down screw and washer keeps me thinking... will overspec the transformer to 400mA most likely...
  51C is a lot and you have yet to case it up.


----------



## fishski13

Quote: 





stixx said:


> Yes, excellent work...
> 
> The measured temp on the toroid hold down screw and washer keeps me thinking... will overspec the transformer to 400mA most likely...
> 51C is a lot and you have yet to case it up.


 

 screwing the TX into aluminum vs wood chassis will bring the temp down a bit, but yes, 51C is quite warm.


----------



## jdkJake

stixx said:


> Yes, excellent work...
> 
> 
> 
> ...







 The screw itself is considerably cooler, but, the overall heat is more than I expected. That being said, if you look at the specs, there should be plenty of available current at 30V. Something like 400ma per secondary. However, the full heat dissipation of 25W is occurring at that load.

 I am no transformer expert, but, I think something closer to the required voltage would probably be far more efficient. Hopefully we will find out soon and the custom sumr will show up to the party.


----------



## runeight

JDK, when you have a minute could you please measure the voltage input to the regulators? Let's see what kind of drop we're getting in the transformer. Also, measure the loaded AC voltage on the secondary.


----------



## jdkJake

runeight said:


> JDK, when you have a minute could you please measure the voltage input to the regulators? Let's see what kind of drop we're getting in the transformer. Also, measure the loaded AC voltage on the secondary.







 Loaded AC voltage on the secondary is ~28.9VAC.

 Where did you want me to take the other measurement,after the rectifiers?


----------



## runeight

At the input pins to the regulators. Or, equivalently, at the +/- terminals of C1R and C2R.
   
  Also, what is the spec on the transformer? Is it 30-0-30?


----------



## studeb

What is the AC level at the socket?
  If that is the Antek mentioned it should be dual 32V secondaries.
  Would going to the 50VA unit AN-0532 improve things?


----------



## runeight

No necessarily. This depends in the input to regulator voltage. The anteks don't have the best regulation IIRC, so let's see what jdk is getting for the voltage first.


----------



## ujamerstand

This thing came a long way from a cowboy hat. Good night everyone.


----------



## stringgz301

Another EHHA rev A lives.  Fairly standard build using Avel-Lindberg transformers (9+9 and 30+30).  No DC offset issues, and the bias is settling in nicely.  I may need to play with the closed loop gain because I barely turn the volume pot to 7:30 with my HF2's.


----------



## jdkJake

stringgz301 said:


> Another EHHA rev A lives.  Fairly standard build using Avel-Lindberg transformers (9+9 and 30+30).  No DC offset issues, and the bias is settling in nicely.  I may need to play with the closed loop gain because I barely turn the volume pot to 7:30 with my HF2's.







 Doesn't count without pictures!


----------



## jdkJake

runeight said:


> At the input pins to the regulators. Or, equivalently, at the +/- terminals of C1R and C2R.
> 
> 
> 
> ...







 http://www.antekinc.com/pdf/AN-0232.pdf

 Output on the secondary is ~29.5VAC

 Input to the regulators (317/337) is 29.6V and -35.4V respectively.

 The best part of these transformers is the price. It will be interesting to see how the other manufacture's measure.


----------



## jdkJake

studeb said:


> What is the AC level at the socket?
> 
> 
> If that is the Antek mentioned it should be dual 32V secondaries.
> ...







 AC from the socket is between 121 to 122VAC depending upon what is running at the time of measure. Biggest hit is of course the HVAC, but even then, it is generally only a 0.5VAC difference.


----------



## jdkJake

ujamerstand said:


> This thing came a long way from a cowboy hat. Good night everyone.







 Nice. I like that much better than the cowboy hat.

 It also makes me less hungry.


----------



## studeb

i guess i will start building then
   
  i was going to order the same anteks yesterday, but i think i will wait a few days to see if the SumR shows up and is any better.


----------



## pabbi1

Quote: 





ujamerstand said:


> .


 


 Good stuff. The Arby's I.P. counsel will sleep better at night.


----------



## stringgz301

Mini review of the newly built EHHA Rev A.  Not sure what I was expecting coming from my SOHA II (that sounded pretty darn good after tweaking with Mundorf SIO coupling caps and ELNA Silmic II power caps).  The EHHA is a startling upgrade, especially in transparency.  The music seems very immediate, effortless, and uncolored.  Bottom end goes way down (Nickelback (a guilty pleasure) Feelin' Way Too Damn Good - I heard bass notes I didn't recall being there) and upper end is very smooth (Jenny Lewis - Pretty Bird sounds like I'm in the studio).  I'm sitting here listening to Jeff Buckley - Grace and the hair is standing up on the back of my neck.
   
  I can see why people describe the EHHA as being very musical.  Awesome.


----------



## sachu

hehe..and people said i was a fanboi of the EHHA..well I am and I have very good reasons for being one. 
	

	
	
		
		

		
			




   
  Its funny, the EHHA has always been described by nearly everyone who listens to it the first time as "effortless"..it never seems to break a sweat and man can it dish out the low end with aplomb..
  Congrats Stringz!!


----------



## jdkJake

I think that is a good description as well. Clean, extended and accurate also fit. Nothing is over wrought nor missing. If the song calls for bass, it is there. If it calls for treble, it is there as well. The top end is most impressive. No grit, no grain, just clean, clear extended sound. The source comes through and let's your phones show their true color.

 I agree the gain might be a bit high for Grados. I have been using the HF-2 as well and barely register a move on the potentiometer.

 Where are those pics? We want pics!


----------



## runeight

Quote: 





jdkjake said:


> http://www.antekinc.com/pdf/AN-0232.pdf
> 
> Output on the secondary is ~29.5VAC
> 
> ...


 

 jdk, could you please check these numbers again. 35V is ok but 29V is not at the input to regs.


----------



## jdkJake

runeight said:


> jdk, could you please check these numbers again. 35V is ok but 29V is not at the input to regs.







 Oops, you are right. Sorry. Measured wrong pin from behind. 

 Right now, after running for quite a few hours we are at +/-33.6V on each regulator on each board. Secondaries are at 28.4VAC.


----------



## stringgz301

Here are a couple of crappy pics from the iPhone
   
  .


----------



## jdkJake

Looks great stringgz! Great job!

 If you don't mind me asking, why did you bottom mount your caps?


----------



## runeight

Quote: 





jdkjake said:


> Oops, you are right. Sorry. Measured wrong pin from behind.
> 
> Right now, after running for quite a few hours we are at +/-33.6V on each regulator on each board. Secondaries are at 28.4VAC.


 


 Thanks. This is really useful info. The regs will have about 3.6V across them which is enough for them to regulate, but really just barely. This means (forgive me gents) that the transformers are slightly underspec'd. They need a higher current rating. Probably 50-100mA per channel. We don't want the input to regs to be too high however, because it will just burn useless power in the regulators. So this is a really tough call as it always is in power supplies. It would be better to have the input to reg voltages at 35-36V, but not higher than this.
   
  My guess is that if the transformer secondaries were at 30VAC all would be well.


----------



## jdkJake

runeight said:


> Thanks. This is really useful info. The regs will have about 3.6V across them which is enough for them to regulate, but really just barely. This means (forgive me gents) that the transformers are slightly underspec'd. They need a higher current rating. Probably 50-100mA per channel. We don't want the input to regs to be too high however, because it will just burn useless power in the regulators. So this is a really tough call as it always is in power supplies. It would be better to have the input to reg voltages at 35-36V, but not higher than this.
> 
> My guess is that if the transformer secondaries were at 30VAC all would be well.









 Did you get a chance to look at the spec sheet? The antek is rated 32VAC at 400mA. Paralleled, under load at 30V they are supposed to output about 790mA.



 Suggest we have stringgz measure the same with his setup. Not sure of the actual model number he is using, but, should give us a couple of looks at the issue.

 EDIT, wrong spec...


----------



## stringgz301

I went with Elan Silmic caps which are larger than most.  In addition, the biggest they make is 1000mF so I paralleled 2 of them on each side of the power supply.
   
   
  BTW Runeight:  I've got 31.7 on the transformer secondaries (it's a 30-0-30 .5A Avel Lindberg).  I'm getting 38.2v on both sides for the regulators (measurement taken across C1 and C2).


----------



## jdkJake

BTW. That measure is drifting. Obviously, I had 35V earlier.

 Just took another, +/-34V with 28.9VAC on the secondaries. Not quite sure what to make of that, any ideas why it would drift so much?


----------



## runeight

34V is ok. Probably thermal drift in the mosfets are slowly changing the bias and this is changing the draw from the PS which, in turn, is changing the filter voltage.
   
  BTW, could you measure TP3 on the heater board. Let's see what the input to regulator is there too.
   
  stringgz301 your voltages are ok. Your PS regs are probably toasty but should be ok too. The Avels regulate better than the Antek so far as I know and the extra 100mA is helping. What are your hot mosfet bias currents?


----------



## sachu

Has everyone on the beta team except me received the boards? Am still waiting on mine.


----------



## stringgz301

My mosfet bias currents are right around 220 mA after being on for 2 hours (I adjusted them).  When adjusted like this they start out at 320 mA when cold and take around 20 minutes to drop.


----------



## jdkJake

stringgz301 said:


> My mosfet bias currents are right around 220 mA after being on for 2 hours (I adjusted them).  When adjusted like this they start out at 320 mA when cold and take around 20 minutes to drop.







 I see the same behavior with mine. Starts out over 300mA when cold and settles at 220mA once warmed up. 

 My test setup is sitting on a countertop close to an HVAC vent. I will measure when the cold air is not blowing on it.


----------



## jdkJake

runeight said:


> BTW, could you measure TP3 on the heater board. Let's see what the input to regulator is there too.







 My heaters are sitting at 6.25V.

 Measuring the regulators: 7.48V
 Secondaries: 6.64VAC


----------



## cobaltmute

Quote: 





sachu said:


> Has everyone on the beta team except me received the boards? Am still waiting on mine.


 

 Haven't got mine up here in Canada yet...


----------



## runeight

So TP3 is at 7.48VDC?? If so, this is enough for an LDO but it can't drop much lower than that. You are using a 7V transformer but the secondary is only 6.6VAC?? This is not a good transformer. 
	

	
	
		
		

		
			




   
  Let's see what happens when the sumr arrives. Hopefully you'll get better headroom on your voltages.


----------



## runeight

It's been quite a while since those boards were shipped. They went first class. They should be to Portland by now and I would think Canada too.


----------



## Beefy

Quote: 





runeight said:


> It's been quite a while since those boards were shipped. They went first class. They should be to Portland by now and I would think Canada too.


 


 FWIW, I've had two packages sent to me recently by Priority Mail - one on September 3, and one on September 7. Neither have arrived yet. Both packages sat in customs for over a week.


----------



## jdkJake

runeight said:


> So TP3 is at 7.48VDC?? If so, this is enough for an LDO but it can't drop much lower than that. You are using a 7V transformer but the secondary is only 6.6VAC?? This is not a good transformer.
> 
> 
> 
> ...







 Yup. That's the measure regardless of HVAC.

 What do ya expect for 10 bucks. LOL. 

 As a good friend of mine always says; cost, schedule or quality, pick any two....


----------



## ujamerstand

Okay, what's an acceptable cost to engrave the logo for you guys? what I have right now costs about 25 @ FPE. To put things in perspective, AMB's logo in the B22 group build is around 20 dollars @ FPE. Smaller = less cost.
   
  Edit: Something like this is about $82...

   
  Quote: 





sachu said:


> Has everyone on the beta team except me received the boards? Am still waiting on mine.


 

 Us Torontonians haven't received ours yet. Our postal system is POS.


----------



## stringgz301

My heater is as follows:  A.L. 9+9V / .83A transformer. 9.94V at the secondary, TP3 is 10.85.


----------



## stringgz301

Quote: 





ujamerstand said:


> Okay, what's an acceptable cost to engrave the logo for you guys? what I have right now costs about 25 @ FPE. To put things in perspective, AMB's logo in the B22 group build is around 20 dollars @ FPE. Smaller = less cost.
> 
> Edit: Something like this is about $82...
> 
> ...


 
   
  That looks very cool.  I like it!  One small correction: it's Revision (not Revition).


----------



## ujamerstand

Quote: 





stringgz301 said:


> That looks very cool.  I like it!  One small correction: it's Revision (not Revition).


 

 Gotta love engrish.


----------



## cobaltmute

Quote: 





runeight said:


> It's been quite a while since those boards were shipped. They went first class. They should be to Portland by now and I would think Canada too.


 

 Next week is my expectation.  It has only been a week.  I've had stuff come in 5 days and stuff come in 25.  I'm ok with a bit later as I was late in ordering my SumR - damn vacations.


----------



## runeight

So, stringg and jdk, you guys have made a few brief comments about the amp's audio delivery. Might you provide any more detail?


----------



## stringgz301

JDK - what tubes are you running in yours?  I'm using some Telefunkens I picked up from Sachu.  
   
   
  It's hard to give a direct description of the sound.  However I can compare it to my SOHA, running Tele 12AU7's.  The EHHA has a more solid and deeper bass, a pleasing but not overly sweet mid-range and an effortless top end.  The instruments are more well defined and separated with clear space in between.  And the instruments sounds incredibly realistic.  You can hear the acoustic guitar string being picked and then vibrating.  With drums it's like you feel the air moving.  It's also very fast: with complex fast moving music you don't lose any of the clarity or musicality.
   
  Overall, it's incredibly enjoyable to listen to.  It's a clear step up from the SOHA II and blows the doors off the Audiotailor Jade in every respect.


----------



## jdkJake

Alex,
   
  Sorry of this has been answered already, but I can see R11 sets the closed loop gain. However, what sets the open loop gain? R13 and R14?


----------



## jdkJake

Quote: 





stringgz301 said:


> JDK - what tubes are you running in yours?  I'm using some Telefunkens I picked up from Sachu.


 

 They are supposedly Amperex, but, they are unmarked.
   
  I also managed to score some marked Westinghouse made in Holland of the same construction, some marked Zenith made in Holland of a different construction and a few other single stragglers (Zenith/Germany, GE/Holland, Amperex/Holland). I was fortunate to get them at a really good price.
   
  I have not rolled any yet. Mainly got them as backups. I hate to build an amp and not be able to get the "as-designed" tubes.


----------



## runeight

Quote: 





jdkjake said:


> Alex,
> 
> Sorry of this has been answered already, but I can see R11 sets the closed loop gain. However, what sets the open loop gain? R13 and R14?


 


 This page:
   
http://www.cavalliaudio.com/ehha/main.php?page=tweaks/gain
   
  is very close to accurate. Make this resistor mapping from EHHA to EHHA Rev A
   
  R12 -> R10
  R13 -> R11
  R22 -> R13
  R23 -> R14
   
  Edit:
  With the stock values for R13/R14 the OL gain is around 700 (similar to b22).
   
  Be careful though about adding more NFB. IMHO is that too much NFB deadens an amp and after some amount of NFB all amps start to sound alike.
   
  Another Edit:
  Use the mosfet tables on the EHHA gain page. The new drivers make the BJT and MOSFET versions about the same.Also, OL gain is more like 500, but this depends some on the hfes of the devices.


----------



## cobaltmute

What are the minimums for open loop and closed loop gain we can run?


----------



## runeight

There are no real minimums, but I wouldn't go any lower than 10k on R13 and R14. This will give you an OL gain of around 75.
   
  Obviously the higher the OL gain and the lower the CL gain the more NFB. I have not checked the stabiliy but with more and more NFB the amp may need more compensation, similar to the EHHA I.
   
  If you socket the four resistors you can experiment to see which sound you prefer.


----------



## jdkJake

Quote: 





runeight said:


> So, stringg and jdk, you guys have made a few brief comments about the amp's audio delivery. Might you provide any more detail?


 

 So, it is still early and I have not used any phones other than my Grados. I won't have a more reflective set of comments until I get more time on it with my HD650's as well.
   
  At this point, my main take-away is on how detailed and refined the sound is straight out of the box. Totally clean and clear, yet never harsh or fatiguing, which, can be an issue, especially with Grados. The amp is extremely detailed and transparent without being overly aggressive or analytical. The amp does so many things right and even at this early stage, apparently nothing wrong. An extremely balanced sound that presents the source in the best light possible. That is about the best compliment I can pay it at this point in time. I am very impressed.
   
  I am figuring out how to move it into my main listening area to try out a number of sources and get the HD650's into the action. They are the true test of versatility and will give me a better idea of how the MOSFET's respond to large voltage swings. 
   
  Well done, Alex.  Well done indeed.


----------



## cobaltmute

jdkjake, just as a reference, what source are you using now?


----------



## jdkJake

Primarily iPod and NAD T-585 (CD only, no SACD or DVDA yet).
   
  I want to get it hooked up to my Keces as I know that source best. I also have a Gamma2 I just built I would like to hear it with, but, that is pretty new and I do not have a reference with it yet, so, I will probably concentrate on the Keces and more of the T-585.


----------



## arteom

*waits for kits to become available


----------



## cobaltmute

Quote: 





runeight said:


> There are no real minimums, but I wouldn't go any lower than 10k on R13 and R14. This will give you an OL gain of around 75.
> 
> Obviously the higher the OL gain and the lower the CL gain the more NFB. I have not checked the stabiliy but with more and more NFB the amp may need more compensation, similar to the EHHA I.
> 
> If you socket the four resistors you can experiment to see which sound you prefer.


 

 So at an OL gain of 75, is a CL gain of around 3-5 reasonable?  Anything else need to be done to handle that?  I find that with my sources I don't need or want a lot of gain.  I easily give up gain for more sensitivity on the volume know.


----------



## runeight

Yes, it is reasonable. But, I haven't got a clue if you will like the amp under those conditions.
   
  To get there with R13/R14 at 10k you need R11 at 3k9. Then my guess is that C2/C3 should be increased to 33p or even 47p to keep the amp stable.


----------



## cobaltmute

Quote: 





runeight said:


> Yes, it is reasonable. But, I haven't got a clue if you will like the amp under those conditions.
> 
> To get there with R13/R14 at 10k you need R11 at 3k9. Then my guess is that C2/C3 should be increased to 33p or even 47p to keep the amp stable.


 

 So in another words, socket the resistors and be prepared to play a little bit.


----------



## ujamerstand

If anyone is interested in a logo design for their EHHA rev.A, I've uploaded a version here: http://www.sendspace.com/file/fr2v9y
   
  In the zip file there are several .plt files, ~hpgl4.plt being the latest version of the design. There is also a .cdr file that you could use to generate hpgl drawings to the exact size you want. You can open it with coreldraw x4 or higher. Just follow the FPE tutorial to create the engraving guides. If anyone wants the uncombined, non-welded work file to play with, pm me and I'll pass it on to you.


----------



## runeight

Quote: 





cobaltmute said:


> So in another words, socket the resistors and be prepared to play a little bit.


 

 Yes. And socket the caps too.


----------



## studeb

Quote: 





> Originally Posted by *runeight* /img/forum/go_quote.gif
> Thanks. This is really useful info. The regs will have about 3.6V across them which is enough for them to regulate, but really just barely. This means (forgive me gents) that the transformers are slightly underspec'd. They need a higher current rating. Probably 50-100mA per channel. We don't want the input to regs to be too high however, because it will just burn useless power in the regulators. So this is a really tough call as it always is in power supplies. It would be better to have the input to reg voltages at 35-36V, but not higher than this.
> 
> My guess is that if the transformer secondaries were at 30VAC all would be well.


 


 I was going to order the anteks yesterday, but thought i should wait to see how jdk works out.
  The next size up antek 0532 "specs" out 1.5V higher at about the same current, 31.5V @0.7A versus 30V @0.79A. That should get the secondaries up to 30V.
   
  I think i will order that one. Anyone have a strong feeling that is dunb?


----------



## runeight

Probably a good idea on the anteks but not on avels. stringg's avel is doing just fine at 500ma while jdk's antek is sweating at over 700mA rating.


----------



## sachu

Quote: 





stringgz301 said:


> JDK - what tubes are you running in yours?  I'm using some Telefunkens I picked up from Sachu.


 

 Wishing right now that i had kept them 
   
  Parts order is in..ama gonna be sniffing solder fumes this weekend..whee.. been missing it for a while now


----------



## jdkJake

studeb said:


> I was going to order the anteks yesterday, but thought i should wait to see how jdk works out.
> The next size up antek 0532 "specs" out 1.5V higher at about the same current, 31.5V @0.7A versus 30V @0.79A. That should get the secondaries up to 30V.
> 
> I think i will order that one. Anyone have a strong feeling that is dunb?







 Realize, the antek I am using is rated 32V/400mA. The 30V spec is from their load test on the spec sheet, so, it might be questionable on how it actually performs at that load (well, I guess that is already obvious).

 Just be prepared as I suspect the next model up (which is double in rating) might be too much. Hard to say. The nicest thing I can say about them at this point is they are cheap. So, you do not lose a whole lot if it does not work. Then again, you do not want to damage the amp to find out. Tough call.


----------



## sachu

I just ordered a coupleof the hammonds that were on the BOM. Should do fine IMO.


----------



## studeb

going dual mono?


----------



## sachu

The board is designed for that..so figured might as well. The two hammonds work out a hair cheaper than a single toroid. And i think i'll take a hammond over an Antek any day.


----------



## jdkJake

sachu said:


> The board is designed for that..so figured might as well. The two hammonds work out a hair cheaper than a single toroid. And i think i'll take a hammond over an Antek any day.







 Probably the wise choice.


----------



## jdkJake

Quote: 





runeight said:


> Yes, it is reasonable. But, I haven't got a clue if you will like the amp under those conditions.
> 
> To get there with R13/R14 at 10k you need R11 at 3k9. Then my guess is that C2/C3 should be increased to 33p or even 47p to keep the amp stable.


 

 Okay, so here is my dilemma. While I would love to reduce the gain to get more travel on the pot, I have no desire to completely change the character of the sound. I like it just fine as it is thank you very much!  
	

	
	
		
		

		
			




   
  So, is there a compromise point whereas I reduce the gain without requiring cap changes and possibly destroying the tonal character of the amp? Say, like around ~2k at R11 and perhaps around ~22k at R13/R14? How low can one expect to reasonably go without getting away from the intended design?
   
  Tough question , I know, but, I had to ask.


----------



## runeight

There is no good answer I'm afraid because it will just be a matter of degree. It may also be that you will not notice high NFB or even like it better. I just don't know.
   
  Generally, with my amps I try to use minimum NFB possible for the given design because this, especially in hybrids, tends to let the tube's sound come through. Too much NFB seems to wash it out.
   
  But I must admit that I haven't personally done a systematic set of listening tests with socketed resistors to create a progression of SQ changes that can be mapped against resistor changes.
   
  Your resistor combination won't require cap changes.


----------



## jdkJake

Quote: 





runeight said:


> There is no good answer I'm afraid because it will just be a matter of degree. It may also be that you will not notice high NFB or even like it better. I just don't know.
> 
> Generally, with my amps I try to use minimum NFB possible for the given design because this, especially in hybrids, tends to let the tube's sound come through. Too much NFB seems to wash it out.
> 
> ...


 
   
  Okay, thanks for the honest answer. I will have to think on it a bit. I really do not want to get into endless resistor combos.
   
  So, I finally dragged the beast into my main listening area. I know I said I wouldn't do it, but, the new Gamma2 was just sitting there and I could not help myself (I am weak that way). Kicked up my favorite Grado test track "Master of Sparks". Yeah buddy! That's the kind! Ya know what I'm talking about!
   
  This amp is good with my SR225's, but, it really shines with the HF-2's. By far, my favorite combo so far. I am starting to develop serious Grado ear, so, it is almost time to break out the HD650's.
   
  In the meantime, it could be a long night....


----------



## stringgz301

I agree with you that it pairs extremely well with the HF2's.  Match made in heaven.


----------



## runeight

Gents, at this point are there 3 of you who have boards? jdk, stringg, and studeb??


----------



## studeb

i can only say i have mine


----------



## runeight

Thanks. That's three that have landed. I sent sachu's to the wrong address and ujamer and cobalt are waiting on Canadian post. Just checking.


----------



## jdkJake

Let's talk DC offset at power on.
   
  I have been measuring it whenever I turn the amp on as well as doing some extra power cycles to get a better idea of how it behaves.
   
  In general, most of the time it spikes somewhere between 1.25V and 1.5V. I have gotten one or two samples as high as 1.7V and *might* have seen as high as 1.9V, but, that might have been operator error, so, I am throwing it out. Like I said, most of the time it is between 1.25 and 1.5V. As for settling time, the amp is in double digit millivolt readings within 3 to 5 seconds upon power on. I would say offset is within single millivolt range in well under ten seconds.
   
  So, tough call on the need for the epsilon 12 circuit. One could always double switch the transformers (separate switches for heater and rail power supplies as mentioned in earlier posts) or just wait a minute before plugging in the phones. I am probably going to build a couple of the epsilon 12 boards and use them just to be safe (and because I kind of want to build them).


----------



## runeight

Good data. I don't know if the settling time would actually improve if the tube was hot. This would depend on a number of factors in the way the rails come up, what charge is left in big capacitors, etc.
   
  This in itself would be an interesting experiment. For anyone with lots of spare time.


----------



## bada bing

Quote: 





jdkjake said:


> Let's talk DC offset at power on.
> 
> I have been measuring it whenever I turn the amp on as well as doing some extra power cycles to get a better idea of how it behaves.
> 
> ...


 


 Do you measure the offset across a load (headphone), or with no load resistance other than the DMM ? Does it make a difference ? The worst case scenario for offset is into low impedance, high efficiency cans like Grados. Do you get that kind of offset spike on turn on, measured across a 30 ohm load or only across an open circuit ?


----------



## stringgz301

Quote: 





runeight said:


> Good data. I don't know if the settling time would actually improve if the tube was hot. This would depend on a number of factors in the way the rails come up, what charge is left in big capacitors, etc.
> 
> This in itself would be an interesting experiment. For anyone with lots of spare time.


 
   
  Settling time with tubes hot after 10 second power down is 20 seconds (to reach < 1 millivolt).  Peak voltage is around 2V.


----------



## runeight

So the settling time is similar for either condition.


----------



## jdkJake

bada bing said:


> Do you measure the offset across a load (headphone), or with no load resistance other than the DMM ? Does it make a difference ? The worst case scenario for offset is into low impedance, high efficiency cans like Grados. Do you get that kind of offset spike on turn on, measured across a 30 ohm load or only across an open circuit ?







 Well I certainly did not perform those measures with my pristine HF-2's plugged into the amp! I suspect the results would be the same, but , perhaps Alex can chime in with the correct answer.

 So, to answer your question, I did not measure under load. Now, if you want to loan me your grado's, I would be more than happy to repeat the tests under load for you. 

 I suppose I could slap a resistor across the output to simulate, but, I would rather not and just take the open measure as a baseline reference. I don't believe it is a big issue with this amp, just don't plug in your phones until it has a chance to settle. Either that or build a couple epsilon 12's and rest assured.


----------



## sachu

Quote: 





runeight said:


> Thanks. That's three that have landed. I sent sachu's to the wrong address and ujamer and cobalt are waiting on Canadian post. Just checking.


 

 hah..well seems the boards got forwarded to a friend's address. Gonna receive them tomorrow and the parts should get delivered same day as well. word up!!


----------



## bada bing

Quote: 





jdkjake said:


> Well I certainly did not perform those measures with my pristine HF-2's plugged into the amp! I suspect the results would be the same, but , perhaps Alex can chime in with the correct answer.
> 
> So, to answer your question, I did not measure under load. Now, if you want to loan me your grado's, I would be more than happy to repeat the tests under load for you.
> 
> I suppose I could slap a resistor across the output to simulate, but, I would rather not and just take the open measure as a baseline reference. I don't believe it is a big issue with this amp, just don't plug in your phones until it has a chance to settle. Either that or build a couple epsilon 12's and rest assured.


 

 I've been "burnt" by offset issues a couple times, and I have a policy to measure offset under load on any amp that exhibits a power on spike unloaded. The "load" I use is 4x120ohm 1/4 watt resistors paralleled ~ about $.25 worth of resistors. The loaded offset will always be at least a bit under the unloaded measurement and in some cases significantly less. My whole idea is to get some notion of what a pair of grados will see before plugging them in. I certainly wasn't suggesting testing a new amp with anything of value jacked in. I probably should have been more clear about what I was interested in.


----------



## jdkJake

bada bing said:


> I've been "burnt" by offset issues a couple times.







 If you don't mind me asking, what happened? Did you lose a decent set of phones?


----------



## BoilermakerFan

Quote: 





sachu said:


> hah..well seems the boards got forwarded to a friend's address. Gonna receive them tomorrow and the parts should get delivered same day as well. word up!!


 
  LMK when your eXStatA boards and the Toshiba FETs show up via email.  I've been absolutely slammed at work so this is my first time on H-F in about 3 weeks. 
   
  Beta builds look great guys.  Where did the "Thumbs Up" smiley go?  That's the one I need man...


----------



## ujamerstand

Something nice arrive at my door today.


----------



## jdkJake

Looks like sachu and ujamerstand are gonna have a busy weekend.

 Excellent news.


----------



## sachu

Got half the resistors soldered down. Am planning to actually socket even the BJT and MOSFET resistors and got transistor sockets for the output devices. This way i can switch to either configuration. Also, I might lay off from populating the boards till next thursday...got some other things going on.


----------



## ujamerstand

Quote: 





jdkjake said:


> Looks like sachu and ujamerstand are gonna have a busy weekend.


 

 Indeed!


----------



## cobaltmute

Even though I got the boards today, my busy weekend will be involved with a co-workers wedding so I'm going to start building next week.


----------



## bada bing

Quote: 





jdkjake said:


> If you don't mind me asking, what happened? Did you lose a decent set of phones?


 


 I destroyed a channel of a KSC75 in a rush to hear music during a DynaHi build.
  Something happened to the servo op-amp, it was maybe defective.
  Nothing else on the amp was hurt. The KSC75 really isn't that hard to destroy.
  There was no loud sound, the driver housing just suddenly got rather warm.
   
  I permanently damaged a set of SR60 during a "burn in" of a set of output caps on a Bijou.
  I was rolling different caps and left an oddball set of "motor run" caps from Ebay playing overnight.
  One channel was audibly damaged on the SR60's, nothing happened to the amp. Post mortem
  revealed there was a slowly varying offset averaging about 50ma on the damaged channel, cap related.  
   
  None of that is really relevant to this build thread, except be careful with good phones on new
  builds till they are well proven. Everybody probably knows that already, but I bet there's a few other
  stories of cheap cans making the ultimate sacrifice in other people's experience. Knowing better
  doesn't always mean doing it, at least in my experience.


----------



## ujamerstand

On the current BOM, the part number for R1 and R3 is swapped with R2 and R3 on the ps tab.


----------



## cobaltmute

Anyone have any good reason not to use CMF55 for all the resistor choices?  1/2W at 70C like the 1/2W BOM resistors, exactly the same part as the RN55 and you can get a slightly better tempco part for slightly cheaper than the BOM RN55.


----------



## jdkJake

cobaltmute said:


> Anyone have any good reason not to use CMF55 for all the resistor choices?  1/2W at 70C like the 1/2W BOM resistors, exactly the same part as the RN55 and you can get a slightly better tempco part for slightly cheaper than the BOM RN55.







 Are they the same size? Some of the pads are pretty tightly spaced. As long as you can make them fit I see no reason not to use them.


----------



## cobaltmute

The CMF55 = RN55.  They are the same part, but CMF is industrial and RN is military.  They de-rate the military part, but as the CMF datasheet says:
  Quote: 





> Except for marking, the Industrial and Military versions are exactly the same. Depending upon stock, military marked parts may be supplied as industrial rated parts


----------



## stixx

When you want to go really Highend get the Dale CMF-55 143 from schuro.de.
  Those are the only ones available non-magnetic... might make a difference...


----------



## jdkJake

Let's talk tube LED lighting.
   
  I know not everyone is a fan of doing it, but, I think it is kinda cool. I like it better than a boring old power-on LED staring at me. Particularly with these low power tubes that have very little heater glow. In any case, I did not use the standard LED specified on the BOM for the tube lights. Rather I went with a high mcd 3.3V/20mA LED to light things up. While I am not a fan of the color I selected (which I am going to change), I do think it worked out quite well. Note, this required a resistor change as well. I calculated a 1.33k was needed at a little over a 1/2W of power dissipation. While I though this would present a challenge, I found that V/D has a series of resistors that are rated from 1/2W to 1W. They are also perfectly sized for the board (think 1/2W package rated to 1W). Very nice. Very convenient.
   
  http://www.mouser.com:80/ProductDetail/Vishay-Dale/CCF601K33FKR36/?qs=sGAEpiMZZMu61qfTUdNhG8UAagspIdBMBJQY5ou0K8I%3d
   
  Anyway, just another option to consider as there are a lot of high mcd LED's at 3.3V/20mA available from numerous places (Mouser, Beezer, etc...).


----------



## ujamerstand

Fail. The carbon resistor I have are too long.
   

   
  Guess I'll have to tombstone these with the resistor mounted as close to the mosfet as possible...


----------



## ujamerstand

...and I missed c8. Well, mine is too big. This is what I get for only buying the difference in parts between the EHHA I and EHHA rev.A BOM. This reminds me; on the current BOM, the part number for R1 and R3 is swapped with R2 and R3 on the ps tab. It also needs the lead spacing measurements for C2, C3 and C8. which are 5mm and 2.5mm respectively. The C2 and C3 part listed on the BOM has 3mm lead spacing, but could be easily bended to suite.


----------



## runeight

Good catch on the resistors. I've got those fixed.
   
  For the caps though, they are mica caps, but their board imprints are larger than the caps. I did this to leave a little more room for alternative caps here. And so I left out the lead spacing in the BoM.
   
  The BoM caps should fit with just a little lead bending.


----------



## jdkJake

Ujamerstand,

 If you want, I have extras on all of the parts, including those resistors and the cap you need. Make a list of what you need and PM your address and I will drop them in the mail to you.


----------



## runeight

Out of curiosity do we have amps other than jkd's and stringg's working yet?


----------



## sachu

Am working on mine, but will probably only fire it up when i have the amp completely built in a case which will be a few weeks time.


----------



## ujamerstand

I'm hoping to have everything running some times the week after, as I try to find fuse holders and appropriate fuses locally this week. A trip to Active surplus it is!
  Quote: 





jdkjake said:


> Ujamerstand,
> 
> If you want, I have extras on all of the parts, including those resistors and the cap you need. Make a list of what you need and PM your address and I will drop them in the mail to you.


 

 Thanks for the offer jdk! The only thing that I have that doesn't fit on the new board is c8. Since its optional I think I'll just bypass it with resistor lead and be done with it. I'll return to it in the next mouser order. Let's see if leaving c8 out causes an trouble.


----------



## studeb

This week was slower than planned, but i should have a running amp tomorrow at the latest.
  I have everything but time..............


----------



## jdkJake

ujamerstand said:


> Thanks for the offer jdk! The only thing that I have that doesn't fit on the new board is c8. Since its optional I think I'll just bypass it with resistor lead and be done with it. I'll return to it in the next mouser order. Let's see if leaving c8 out causes an trouble.







 Okay, let me know if you change your mind.

 BTW, I am running a 2A fuse. I figure at a max draw of 1.8A with the sumr, that should be just about right.

 Speaking of which, I got word from Richard Sumr. They were running behind on the epoxy process. Hopefully it shows up sometime this week.


----------



## ujamerstand

Good to know, I was going to shoot them an email myself today, but never got around to do that.


----------



## studeb

i will not make it until Monday, somehow i ended up with 3 78L15 and 1 79L15.
  not sure i'd trust it no servo


----------



## studeb

Here is where i am:

   
  getting there
   
And with sockets


----------



## sachu

Nice..MOSFET or BJT?


----------



## gurusan

Looking pretty good!


----------



## jdkJake

Looking real good studeb.


----------



## studeb

Thanks guys,
   
  Sachu, that is mosfet
   
  i have in my mind to set this up as a speaker amp in the end, but that will be a while off.
  i think your estimate of three hours was pretty good, for you. I think it was proabably closer to four for mortals like me.


----------



## runeight

I should have ordered a set of those boards for me.


----------



## jdkJake

runeight said:


> I should have ordered a set of those boards for me.







 I figured you were too busy. Starting to get curious huh?

 If you were not so far away, I would invite you over for an adult beverage or two to check it out.


----------



## runeight

Quote: 





jdkjake said:


> I figured you were too busy. Starting to get curious huh?
> 
> If you were not so far away, I would invite you over for an adult beverage or two to check it out.


 


 Yes I am.


----------



## sachu

I should have the amp ready in the next few weeks. the chassis came in today. 
  I'll loan the amp out to you Alex for a bit after it is done. 
	

	
	
		
		

		
		
	


	




" class="bbcode_smiley" height="" src="http://files.head-fi.org/images/smilies//smily_headphones1.gif" title="
	

	
	
		
		

		
		
	


	




" width="" />. 
   
  p.s Btw, waiting on a reply to an email I sent a day or two ago..


----------



## jdkJake

sachu, is that the 12x12x4 Par Metal you were referring too in an earlier post?


----------



## sachu

yes indeedy. Am fine tuning the panel design for this.


----------



## jdkJake

Cool. I put mine on order late last week, but, have not yet received a confirmation back from par-metal. How long did it take for them to turn the order around?
   
  I am gonna give the 12x12x3 version a go. I like the low profile look myself.


----------



## cobaltmute

Is the actual clear space 12x12 or is it smaller?

 I'm want to use that case but on black


----------



## sachu

Quote: 





jdkjake said:


> Cool. I put mine on order late last week, but, have not yet received a confirmation back from par-metal. How long did it take for them to turn the order around?
> 
> I am gonna give the 12x12x3 version a go. I like the low profile look myself.


 

 With the tubes in, depending on how tall your spacers are, it will be near impossible to fit them in a 3 inch high case.
  Ordered it from John Ango from ebay. Got it in just over a week. I've bought all my par-metal chassis from him. I think he manages the ebay front for Antek and Par metal. I have two more chassis just like the one in the picture sitting here 
	

	
	
		
		

		
		
	


	




  
  Quote: 





cobaltmute said:


> Is the actual clear space 12x12 or is it smaller?
> 
> I'm want to use that case but on black


 

 It is nearly 300x 300mm (probably smaller by a mm or two).


----------



## jdkJake

Quote: 





sachu said:


> With the tubes in, depending on how tall your spacers are, it will be near impossible to fit them in a 3 inch high case.


 

 I measured it multiple times. It will be tight, but it should fit. Provided the case is actually 3 inches tall.


----------



## sachu

Yup..very tight actually. I built two EHHAs a few months back in a 3 inch tall case and just barely managed to keep the tips of the tubes from touching the top of the case.


----------



## jdkJake

So, on a slightly different topic, I have been using the HD650's for the past couple of days.
  I could wax poetic, but, all I can think to say right now is best summarized as "_Holy Crap this amp sounds good!_".


----------



## sachu

Yup, that amp really makes the Sennheisers shine!! Heck fell in love with the amp for the first time after listening to it nearly 3 years ago with a pair of HD580s.  You should "graduate" to orthos, or atleast give them a whirl, you might just become an orthohead 
	

	
	
		
		

		
		
	


	




" class="bbcode_smiley" files.head-fi.org="" height="" http:="" images="" p="" smilies="" src="http://files.head-fi.org/images/smilies//smily_headphones1.gif" title="
	

	
	
		
		

		
		
	


	




" width="" />
   
  Glad to say that an EHHA was recently brought to life back home in India (BJT version with toshiba 2232/968s) and from what I hear (take a bow Gurubhai  ), there are atleast a couple more on the way. So happy to see this amp getting the attention it so richly deserves.


----------



## sachu

Some comparisons with your other amp would certainly be insightful Jake..when you find the time of course


----------



## jdkJake

It is hard to put down right now, that is for sure.

 I will provide more useful observations, but, I want to spend a bit more time with it and the HD650's before I comment too much further.


----------



## stringgz301

Sachu - what's his eBay seller ID?  
  
  Quote: 





sachu said:


> With the tubes in, depending on how tall your spacers are, it will be near impossible to fit them in a 3 inch high case.
> Ordered it from John Ango from ebay. Got it in just over a week. I've bought all my par-metal chassis from him. I think he manages the ebay front for Antek and Par metal. I have two more chassis just like the one in the picture sitting here
> 
> 
> ...


----------



## sachu

http://myworld.ebay.com/johnango/


----------



## jdkJake

You can also order directly from their web site. It is the same guy. I know as he confirmed shipment of my case. Should have it by Friday at the latest. 
   
  Now I just need the custom transformer to make an appearance.
   
  In the meantime, HD650's are getting a workout.
   
  www.par-metal.com


----------



## studeb

Powered up the boards tonite.
  As expected the 7v antek gave 7.5V at TP3, but i still got 6.3V with tubes installed.
  Without the amp connected i got +/- 30.1V at the power supply.
  Will get more done tomorrow


----------



## jdkJake

studeb said:


> Powered up the boards tonite.
> 
> 
> As expected the 7v antek gave 7.5V at TP3, but i still got 6.3V with tubes installed.
> ...







 Good to see things are moving right along. Which transformer did you end up going with for the +/-30 supplies?


----------



## studeb

i went with the 50VA version


----------



## jdkJake

Got word from Richard at Sumr, my transformer shipped yesterday via Canada Post. Yeah!
   
  Now I am on the other side of the transit wait cycle (Canada to USA).
   
  Any bets on the date it shows up?


----------



## jdkJake

BTW, this amp resolves like a MoFo.
   
  I can clearly hear a difference between the filter settings on the gamma2. The settings have a subtle effect on the sound, but, it is definitely discern-able.
   
  Nice.


----------



## ujamerstand

!!!!!!!!!!!!! Are you serious?! I could not tell the difference between the various settings on gamma2 with my millett hybrid, no difference at all. Must finish all my assignments and continue building.


----------



## jdkJake

I know, I know, sounds crazy, but, I swear it is true.
   
  You can't switch back and forth, per se, you have to listen a bit with each of them and get a flavor for what they really do. A high quality, rather open recording helps as well. I threw on Steely Dan's "Two Against Nature" which is always good for critical listening, be it speakers or headphones. Good tunes as well (if you are a Dan head).
   
  Anything with well-recorded vocals really shows the difference. Any recording with a sense of space or air. Flat out rock does not really do it.


----------



## ujamerstand

Not crazy at all. It shows EHHA's superior design. Which means I must finish it ASAP so that I could see if I could experience what you are experiencing.


----------



## johnwmclean

Speaking strictly in reference to the EHHA I, it’s the best headphone amp I’ve ever heard, period. I was able to hear chair squeaks before the EHHA, now I can hear the outside traffic noise, diesel and unleaded are clearly discerned. 
   
  I’ve just ordered “The Horn” speaker from Ed at The Horn Shoppe, I can’t wait to give these babies a workout with this amp.


----------



## cobaltmute

Started my build today.
   
  Also discovered that I ordered the wrong heatsinks for the heaters.  Hope its the only wrong thing I ordered.


----------



## sachu

Quote: 





johnwmclean said:


> Speaking strictly in reference to the EHHA I, it’s the best headphone amp I’ve ever heard, period. I was able to hear chair squeaks before the EHHA, now I can hear the outside traffic noise, diesel and unleaded are clearly discerned.
> 
> I’ve just ordered “The Horn” speaker from Ed at The Horn Shoppe, I can’t wait to give these babies a workout with this amp.


 








I told you so!!
	

	
	
		
		

		
		
	


	



   
  Oh, and I came home to these sitting in my mailbox today. 
	

	
	
		
		

		
		
	


	




  
   
  The teles are still in their plastic wrapper while the Ges are all NOS as well and are "made in Holland". Definitely made in the Amperex factory. Not many turned out these low voltage tubes back in the day.


----------



## ujamerstand

Do I see factory plastic on the telefunkens?


----------



## studeb

number three is running
  no issues at all, the 50VA transformer is not sweating. The regs are hot though.
   
  i can go over the numbers and SQ later, i am too tired and have a headache to go on much longer and i have to move to my stereo as my minidisc player is not the final word in sources. But for now, i will say this amp is superb. gobs of detail, bass control, dare i say PRAT? I got a tube rush/hiss with the Sony MDR-V6, but with AKG sextetts that is gone.


----------



## jdkJake

johnwmclean said:


> Speaking strictly in reference to the EHHA I, it’s the best headphone amp I’ve ever heard, period. I was able to hear chair squeaks before the EHHA, now I can hear the outside traffic noise, diesel and unleaded are clearly discerned.
> 
> 
> 
> ...







 High praise from a man who also owns a B22! Indeed, it is a very impressive piece.

 Those speakers look very interesting. I will be very curious to hear your impressions of them. The web site is also a trip. I like the Horn 2 just for the optional speaker grills. 

 Did I read somewhere correctly that, for speakers, you are putting out around 20W?


----------



## jdkJake

studeb said:


> number three is running
> 
> 
> no issues at all, the 50VA transformer is not sweating. The regs are hot though.
> ...







 Great news studeb. Be sure to post some pics when you get a chance.


----------



## jdkJake

cobaltmute said:


> Started my build today.
> 
> 
> 
> ...







 I have extras on the 2inch parts. Drop me a PM if you want me to send them up.


----------



## cobaltmute

Quote: 





jdkjake said:


> I have extras on the 2inch parts. Drop me a PM if you want me to send them up.


 
   
  Thanks for the offer, but I also discovered that between making the BOM and uploading the parts list to Digikey, I totally dropped all the 1uF box caps.  I've got to order those as well, so I'm just going to order my stuff.  That way I'll get it by the weekend and at least build while I wait for my transformer.


----------



## johnwmclean

Quote: 





jdkjake said:


> Did I read somewhere correctly that, for speakers, you are putting out around 20W?


 

  
  or 50Wrms into 8Ω fully-balanced


----------



## cfcubed

*OT* but, if the amp pairs well with those horns, think you'll be very pleased.  Positioning for them is important, but my speaker-buying days have been over since picking them up.  Full-rangers are a great complement/equivalent to high-end cans IMO.  Guess you'll be letting us know what you think
   
  BTW, picked up Ed's "Bass Augmenter" when I was using a DIY FW F2 w/them, but don''t need or use it w/my DIY FW F1:
   



  Quote: 





johnwmclean said:


> <snip> I’ve just ordered “The Horn” speaker from Ed at The Horn Shoppe, I can’t wait to give these babies a workout with this amp.


----------



## runeight

Nice to hear that amp #3 is running. Only two more to go while John happily listens to his speaker amp. 
	

	
	
		
		

		
		
	


	



   
  Gents, I will not be available much from Fri through Sun. Won't be able to troubleshoot if needed, but it appears that the builds are solid.


----------



## sachu

eeerrr 3 more..thought we had 6 folk building, Umjer, cobal and myself left. Am gonna be busy this weekend at the Seattle meet, but next week for sure i plan to wrap things up.


----------



## cobaltmute

I'll be using my free time over the next little while to build the boards and other bits that are going into my total package.  I've still got to wait for my transformer, but my bench supply will do +-24 so I may power up the amp portion of the boards sooner.


----------



## jdkJake

Quote: 





johnwmclean said:


> or 50Wrms into 8Ω fully-balanced


 


   Wow, that is more significant than I expected. Hmmmm.....


----------



## runeight

Quote: 





sachu said:


> eeerrr 3 more..thought we had 6 folk building, Umjer, cobal and myself left. Am gonna be busy this weekend at the Seattle meet, but next week for sure i plan to wrap things up.


 


 Right, 3 more.
   
  Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


----------



## fishski13

Quote: 





johnwmclean said:


> Speaking strictly in reference to the EHHA I, it’s the best headphone amp I’ve ever heard, period. I was able to hear chair squeaks before the EHHA, now I can hear the outside traffic noise, diesel and unleaded are clearly discerned.
> 
> I’ve just ordered “The Horn” speaker from Ed at The Horn Shoppe, I can’t wait to give these babies a workout with this amp.


 


  John, it's been years since i've heard Ed's Horn, but once you go FR, it's hard to imagine wanting another pair of conventional multi-way.  i would also consider building one of Pass's F1-F5.


----------



## johnwmclean

Sorry OT again,
   
  cfcubed and fishski 13, great horn feedback. Pass FW’s have already sparked my interest for a while.


----------



## Cloud

ME! 
	

	
	
		
		

		
			




  
  Quote: 





runeight said:


> Right, 3 more.
> 
> Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


----------



## limpidglitch

Quote: 





runeight said:


> Right, 3 more.
> 
> Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


 

 Guilty.
   
  I've been keeping an eager eye on the progress here in hope of having one built this christmas.
  It all looks very promising.


----------



## BK_856er

Quote: 





runeight said:


> Right, 3 more.
> 
> Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


 

 Yes, I'm in! Sign me up!!
   
  BK


----------



## arteom

Quote: 





runeight said:


> Right, 3 more.
> 
> Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


 

 Definitely going to order a set of boards or kit when available.


----------



## jamesbobo007

Yep, I'm still interested


----------



## studeb

As an update, mounting screws for Mosfets and 3X7 regs are about 60 degrees C
  That is after about an hour idling.
  I do see very large offsets on power up.


----------



## jdkJake

studeb said:


> As an update, mounting screws for Mosfets and 3X7 regs are about 60 degrees C
> 
> 
> That is after about an hour idling.
> ...







 Did you get a chance to measure the input to the regulators for the rail supplies? I am most curious to see what the drop is with the 50VA part vice the 25VA part.


----------



## dwh91307

I'am another lurker awaiting kit or board sale.
   
  DH


----------



## studeb

Here is what i measured:
  AC -
  Wall 121.5V
  Secondaries 31.65V and 6.75V
   
  DC -
  After diodes +/- 39.6V and 7.7V (Tp3)
  At output 30.09V/-30.15V and 6.28V
   
  i'll try get under for the regs
   
  Edit: temp at top of heatsinks for Mosfet and 3X7 regs is 40-42 C, and bias does start out high, then drops with warm up


----------



## Andrey81

Quote: 





runeight said:


> Right, 3 more.
> 
> Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


 
  I'm also interested.


----------



## jdkJake

studeb said:


> Here is what i measured:
> 
> 
> AC -
> ...







 Depending upon the exact point of the measure above, I suspect you are going to get pretty much the same numbers on the inputs to the regulator.

 Well it certainly does not appear to be lacking for power. Based upon some of the comments Alex made earlier, that 39.6 might be a bit too high. No wonder those heat sinks are at 60C.

 These Anteks look to be like Goldilocks and the Three Bears. Mine, a bit too low and yours a bit too high. If we could only get one "just right".


----------



## lozanoa11

I am interested as well. Was going to build the original until I saw this thread.


----------



## blippster

Probably interested in a stereo board set, kits would be good too.


----------



## TheShaman

Kits would be great!


----------



## fishski13

it's great to see a lot of unfamiliar DIYers (to me anyway) interested in boards.  this should be a fairly straight and forward build.  i'm still in for 2 stereo pairs...that is if Sachu hasn't driven up the 6GM8 to unobtanium 
	

	
	
		
		

		
			





.


----------



## sachu

haha..well i landed the teles on a second chance offer on fleabay  and then a day later there was Max with his huge tube sale on DIYA and the 6GM8s were going cheap too. Too good a deal to pass up knowing how rare they have become. One pair of the GEs is already destined for Ujamer.


----------



## WyldRage

Quote: 





runeight said:


> Right, 3 more.
> 
> Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


 
   
  Yes.


----------



## BoilermakerFan

Quote: 





johnwmclean said:


> Speaking strictly in reference to the EHHA I, it’s the best headphone amp I’ve ever heard, period. I was able to hear chair squeaks before the EHHA, now I can hear the outside traffic noise, diesel and unleaded are clearly discerned.
> 
> I’ve just ordered “The Horn” speaker from Ed at The Horn Shoppe, I can’t wait to give these babies a workout with this amp.


 

 Interesting to see how many of us Cavalli Audio fans are also FR driver fans...
   
  Here's some FR driver pron:
   




   
  They are Tang Band W8-1808s.  In transit to me as they were just completed by Dave at Planet 10 Audio and they will be going into Decware's Zen Open Baffle speakers that will be built with Walnut ply baffle/sides and Corian for the bass cabinets.  I'll probably use them again in an enlarged Fonken GR or Castles design next. 
   
  My Liquid Gold prototype will be pushing close to 15W/ch balanced and I plan to push the EHHA Rev. A's to 15W/ch minimum, probably closer to 35W later. 
   
  I also have AudioSector F5 boards and I do plan to build up that beast too.  It's getting a modded PS to really drop the noise and ripple so it can drive headphones as well as speakers.  I plan to compare the F5 to the EHHA Rev. A  and future commercial Cavalli Audio prototypes unless the EHHA Rev. A really just spanks the F5 when it's at 35W/ch.  If that proves to be the case as I suspect it will be, I'll just sell off the populated F5 boards then mod the PS for the EHHA and bump them up to 50W.   
   
  AC, when your back online, I'm in for four boards.  Maybe five as I have a tendency to toast one when soldering a little too hot.  
	

	
	
		
		

		
		
	


	




  I can always run the single as an active ground.


----------



## jdkJake

Quote: 





sachu said:


> haha..well i landed the teles on a second chance offer on fleabay  and then a day later there was Max with his huge tube sale on DIYA and the 6GM8s were going cheap too. Too good a deal to pass up knowing how rare they have become. One pair of the GEs is already destined for Ujamer.


 

 DIYA? Is that the name of a site?


----------



## sachu

diyaudio.com


----------



## fishski13

sorry for the OT...
   
  Boiler,
  nice drivers!  i've built 2 different Planet-10 designs for the Fostex  FF85K.  i'm listening to my y2/B1/F5 as i type.  after owning Naim, Krell and ATC, none of them compare to these simple DIY projects.  i also built a remote PS for the F5 with added caps in the amp proper and 12AWG wire with the intention of driving my K702.  i have yet to hook them up, but i'm hoping the PSRR of the design is good enough with a simple CRC PS without adding monster inductors.  i just need to add a couple more coats of tung-oil on the sapele wood PS chassis and cut the top-plate and she's done.  i'm using PD's boards as well.  there's a good reason why the F5 is so popular...
   
 http://i23.photobucket.com/albums/b353/fishski13/F5/IMG_5489.jpg 
   
http://i23.photobucket.com/albums/b353/fishski13/F5/IMG_5492.jpg
   
http://i23.photobucket.com/albums/b353/fishski13/uFonken2/016.jpg


----------



## studeb

Nice set up Fishski.
   
  here is a photo of number 3


----------



## jdkJake

Nice work studeb!

 Any ideas on casework yet?


----------



## fishski13

studeb,
  thanks.  any noise issues?  i'm guessing the plank is around 10"x 16"?


----------



## studeb

board is supposed to be 12x14
  will make a wood and metal case
  As it is it is pretty quiet.


----------



## stixx

Not really lurking but of course still interested...
  Need to find some space though this becoming amp nr. 8


----------



## fishski13

Quote: 





studeb said:


> board is supposed to be 12x14
> will make a wood and metal case
> As it is it is pretty quiet.


 

 wood and metal always look good, especially if DIYed 
	

	
	
		
		

		
		
	


	




.  
   
  stixx,
  i hope your EHHA looks as sexy as your M3.  if memory serves me correct, your dining room has plenty of space for amps...and Schwarzbier.


----------



## rx7mark

I'm interested in 4 boards for a balanced build, though I haven't decided between Rev A or EHHA I.
   
  I haven't decided if I want the speaker capability of the EHHA I or not.
   
  Mark


----------



## stixx

Quote: 





> i hope your EHHA looks as sexy as your M3.  if memory serves me correct, your dining room has plenty of space for amps...and Schwarzbier.


 
   
   
  fishski13, your memory is mighty good... 
	

	
	
		
		

		
			




   
  I do like the compact size of the EHHA rev boards a lot... gives quite a few options to case it up nicely.
  So far I just have a remote idea though.


----------



## egotrip

This is my first post on a HiFi / Head-Fi forum ever, And i love the idea of a D.I.Y. project.
  I tend to read too much before i decide, witch can be both good, and bad.
  I have read almost the whole SOHA II builders Thread (page73) when i discovered EHHA
  I was wondering if its worth to read the EHHA build thread og 100++ pages, including this thread too.
  Just to find out that the first suits my need better?
   
  So my question for further investigation is:
  What are the major difference between SOHA II and EHHA/EHHA rev A
  since i have a lot more reading more to do, could someone please help me out with this?
  and: When will the kit of Rev A become avaiable?
   
  And i would beat you to this, Welcome, and sorry about my wallet 
	

	
	
		
		

		
		
	


	



   
  My first HeadAmp will become a DIY, and it will be a Cavalli Audio Project.
  Choises. Please Help me decide.


----------



## stringgz301

Differences between SOHA II and EHHA Rev A from a build perspective:
   
  - SOHA II is on a single board and uses a single transformer so is less expensive, simpler to case
  - SOHA II uses more commonly available tubes than EHHA (6GM8).  6gm8's are also getting pricy
  - EHHA rev A build requires much more wiring than SOHA II, where the pot and jack can be connected directly to the board.  So EHHA requires more planning of layout inside case.
  - Besides tube rolling, SOHA II allows you to roll coupling caps.  This allows additional tailoring of sound.
   
  Neither build is terribly complex.  Soundwise, my opinion is that the EHHA is a step up.


----------



## egotrip

I took a look at glassjaraudio and noticed that EHHA (first rev) is a complete kit.
  But not the SOHA II, just the PCB.
  Does GJA have a complete kit of the SOHA II avaiable if I ask him?
  A complete kit is less hazzle, due to parts avaiability.


----------



## Cloud

GJA do have SOHA II kits. i gotten mine from him


----------



## egotrip

they only have SOHA II PC board listed.
  Still not convinced about the SOHA II vs EHHA


----------



## TimJo

^ What headphones are you going to be driving with the amp?


----------



## egotrip

DOH....
   
  The latest design from Cavalli Audio, SOHA II v. 1.1. US shipping included. Kits are available please email. International customers please contact us.
   
  If i decide for the SOHA II, i'll send him an e-mail.
   
  Pros, and Cons on the difference on EHHA and SOHA II would be great.
  And if anyone knows, when do you think the Rev A is avaiable as a kit?


----------



## stringgz301

What source are you using?  The EHHA is very transparent so a weak source would not be good.  With the SOHA you can use tube and coupling cap rolling to tweak the sound (although this isn't optimal).
   
  My 2 cents: since I built my EHHA rev A the SOHA II hasn't been turned on once.


----------



## egotrip

I am using my laptop, android, or my Nad Reciever as a source.
  But i was thinking of implementing a USB dac into the build.
   
  I am an bass head, therefore I have the Sennheiser eH150, these where bought before i was thinking of an amp at all.
  and I am about to order the 250ohm of the Beyers DT770 Pro later, I have listened to the 32 ohms edition of these at a friends house. I think the 250 ohm with a good amp would do greater.


----------



## jdkJake

You also did not mention how much you are willing to spend. The EHHA will be the more costly to build of the two.


----------



## egotrip

Price is not an issue.
  After my calculations, i could come far with $200 +- on both of these builds


----------



## jdkJake

I doubt seriously you can build, power and case a EHHA for $200USD. 

 But I may be wrong. Depends upon your choice of transformers, your casework material/skills and source for tubes.


----------



## egotrip

according the todays currancy, i have $341,38 set aside to a project amp.


----------



## stixx

When this is your first amp/DIY project it is usually advised to start a bit smaller and not throw all your money into the first project (says me who did pretty much the contrary...
	

	
	
		
		

		
			





).
  From another perspective it might also be smart to start with.. like... medium level since the SOHA II already has become a capable amp. Once you have finished it, cased it up, solved the problems that might come along the way you will be so happy to almost instantly start the next project....
  and THEN the EHHA revA sure is a step up.
   
  Just speaking out of own experience...


----------



## egotrip

Thanks stixx, that seems like a good idea.
  I think i will start off with the soha II as a first build, and continue on with the ehha rev a later.
  maybe at that time, it has been released as a kit. 
   
   
  Quote: 





> From another perspective it might also be smart to start with.. like... medium level since the SOHA II already has become a capable amp. Once you have finished it, cased it up, solved the problems that might come along the way


 
   
  Your statement has been the most convising yet.
  I know by my own learningskills, i can complete the Soha II and probably solve out the issues in the way, based on the forum threads of the build.


----------



## stixx

Go for it... you will not regret.
  Building your own audio gear is a very satisfying way to spend your time and money!


----------



## funch

Quote: 





runeight said:


> Right, 3 more.
> 
> Are there any lurkers on the thread who have been waiting for completion of the beta phase to express interest in boards/kits?


 


      I've been seriously considering doin' the balanced thing using four RevA boards.


----------



## jdkJake

Well, it's been over a week with the HD650's...
   
  Smooth, extended, detailed, controlled. Without a doubt the biggest soundstage I have heard with the HD650. I must admit I was slightly worried the MOSFET's would hold it back, but, that does not appear to be the case. It does not come across slow or sluggish, just effortless power (and gobs of it). Perhaps a bit too much mid-bass, but, that is most likely the HD650 rather than this amp. It will be interesting to contrast this build with the BJT version I plan on building as a follow up (at this point, I MUST, HAVE, BOTH! <evil laughter>). 
   
  Still no issues with the amp itself. It is holding bias just fine with no heat related issues. The only thing the appears to be breaking a sweat is the Antek transformer and even that is holding up just fine so far.
   
  Very, very impressive.


----------



## cobaltmute

Considering that HD650's are my primary listening source, I'm looking forward to completing my build.  Especially since they sound fantastic with my DAC and amp combo right now.
   
  It will be interesting though, as my will be a BJT build.  Will need to meet up with someone to compare to a MOSFET build at some point in the future...


----------



## jdkJake

Did you decide on which BJT's you are going to use?


----------



## cobaltmute

2SD1763A and 2SB1186A.  I have spares from an original Kumisa III project I'm working on.


----------



## ujamerstand

Just finished my assignment. Will start on the rest of the build ASAP. Cobalt, my build is a mosfet build (IRFZ24N, IRF9Z34N), so we could arrange a meet sometimes.


----------



## jdkJake

cobaltmute said:


> 2SD1763A and 2SB1186A.  I have spares from an original Kumisa III project I'm working on.







 Now that is interesting. I am not familiar with those parts and have not read much about them. I will be most curious to hear what you think of them.

 I will probably build with the reference parts, but, I have some toshiba parts I would not mind trying (2232/968) , I am just not sure if they are counterfeits or not. I have never used a transistor socket, perhaps I might give that a go.

 Anyone have any recommendations on transistor sockets for TO-220 packaging?


----------



## jdkJake

ujamerstand said:


> Cobalt, my build is a mosfet build (IRFZ24N, IRF9Z34N), so we could arrange a meet sometimes.







 Whew! Thanks ujamerstand, that saved me from volunteering to make a REALLY long drive!


----------



## cobaltmute

ujamerstand - when we get built to the point we can move amps around, definitely sounds like an idea.


----------



## cobaltmute

Quote: 





jdkjake said:


> Whew! Thanks ujamerstand, that saved me from volunteering to make a REALLY long drive!


 

 But you know you want to visit our fall weather.  At 8am this morning it was 4C outside.


----------



## jdkJake

Quote: 





cobaltmute said:


> But you know you want to visit our fall weather.  At 8am this morning it was 4C outside.


 


   That is true. More so to see fall color than anything. That is what I miss most about living up North.
   
  Hmmm....


----------



## runeight

Gents, there seems to be interest for both boards and kits. I have been talking with Jeff at Glass Jar. I would not be able to offer kits, but Jeff can do that if there is enough interest.
   
  It would also be a bit easier for me, now that the beta builds appear to be successful, to transfer supplying the boards/kits to Jeff. As you all know, Jeff has been handling all of my diy type amps for several years.
   
  If anyone has objection to this step please PM me or email at alex@cavalliaudio.com. And don't hesitate either because I want to know what you think.


----------



## sachu

Couldn't think of a better person to handle this for you Alex.  I would say Jeff is probably the only person geared for offering kits for this amp.


----------



## qusp

hmm OK, sounds like I dont have to rush out and grab boards, i've over committed with headamp/preamp projects I have on my plate from over at the other DIY forum with the time I have available to me, a pair of DCB1 salas blue versoin buffers, a balanced Dispre II V4 JFET and a DIY X'd ciclotron DAO follower, so will see how things progress, does sound like it has been another success though, congrats.
   
  as you can see pretty sandy builds, tubes still luring me, but will have to wait till after an unexpectedly soonish house move.


----------



## jdkJake

runeight said:


> Gents, there seems to be interest for both boards and kits. I have been talking with Jeff at Glass Jar. I would not be able to offer kits, but Jeff can do that if there is enough interest.
> 
> 
> 
> ...







 Works for me as long as Jeff continues to offer board-only options.


----------



## runeight

Yes, this would be the plan. The real issue, I think, would be the interest in kits. Boards are easy, but kits are harder because they involve holding much more inventory. So, without speaking for Jeff, there would have to be enough interest in kits or forseeable interest in kits.


----------



## lozanoa11

I would buy a kit if I went threw with this.


----------



## fishski13

Quote: 





runeight said:


> Yes, this would be the plan. The real issue, I think, would be the interest in kits. Boards are easy, but kits are harder because they involve holding much more inventory. So, without speaking for Jeff, there would have to be enough interest in kits or forseeable interest in kits.


 
  the fact that the expense of a o22 (insert other favorite regulated PS) has been dispensed with with the inclusion of an "on-board" PS, i think kits would be popular.


----------



## Lil' Knight

I'm definitely in for a kit. Agree that having an included PSU is a plus and the chassis would be much smaller and easier to deal with.


----------



## fishski13

Quote: 





lil' knight said:


> I'm definitely in for a kit. Agree that having an included PSU is a plus and the chassis would be much smaller and easier to deal with.


 
  great (and poor) minds think alike.


----------



## Sathimas

I'd also be interested in a kit but not right now - I already built the exstata this year and my jisbos based preamp,
  so my funds for DIY-Audio are a little low


----------



## stixx

Boards only for me... I prefer the ability to choose the components myself, plus I might have some parts in my drawers already...


----------



## Andrey81

I would buy a kit.


----------



## TheShaman

Interested in a kit.
  Jeff's definitely the man for the job.


----------



## keyid

would love semi-kits, I remember in the past Jeff had a bom like order form which allowed patrons to choose various components along with the board.


----------



## cfcubed

I bet that's the way Jeff would do this, think that's what he did w/all 3 differing kits I've ordered from him (sent parts/cost spreadsheet for edit/review).
Alex - you can add me as one that would someday buy a kit for this project.  Getting back to building soon but have to build out the 3 or 4 projects I've parts for first.
  Quote: 





keyid said:


> would love semi-kits, I remember in the past Jeff had a bom like order form which allowed patrons to choose various components along with the board.


----------



## Cloud

Full kit or board only is fine with me. The most important question: when will be the public release? i cant wait to get my hands on them


----------



## Cloud

Full kit or board only is fine with me. The most important question: when will be the public release? i cant wait to get my hands on them


----------



## WyldRage

Would prefer a kit, but boards-only is fine by me.


----------



## limpidglitch

I'll commit myself to a kit.


----------



## BK_856er

I've already expressed interest further up, but sure I'd be more than happy to purchase through Jeff.
   
  BK


----------



## ujamerstand

SumR transformers due for arrival tomorrow. I must finish building tonight.


----------



## jdkJake

Got back from a road trip tonight and had a present waiting for me:
   

   

   
  Looks really good. I really like the inclusion of the test and verification sheet. A very nice touch.
   
  I am a bit too tired to work with it tonight (a long, long day of day-job activity and plane flights), but, I will hook it up tomorrow and let you know how she rolls.
   
  BTW, this is fully shielded and encapsulated.


----------



## cobaltmute

I'm not sure when my SumR will ship (I was late in the ordering), but my boards will be done by the end of the weekend for sure.


----------



## fishski13

Jake,
  those TXs look nice.  SumR provides an excellent service to those needing custom TXs.


----------



## Jrossel

Hello EHHA Fans,
   
  I will be making kits for these and will also stock the boards.  It is nice to see all the interest in this project, as the EHHA is an amp that needs to get out there and be listened to.  I will be working with Alex to get a number of boards fabricated and they will be available in the store in about a month.
   
  Talk to you soon,
   
  Jeff


----------



## th3bl0b

I know this has been going on, but I'm definitely in having a part of this! It looks like it'd be good fun.


----------



## stixx

Quote: 





> I will be working with Alex to get a number of boards fabricated and they will be available in the store in about a month.


 
   
   Great!!
   
  As soon as they pop up in your store I will be ordering...


----------



## ujamerstand

Soo close. Yet soo far away.
   
  Edit: yeah, far away indeed. I've got a short on one channel between v- of the servo and ground. tracing the circuit for shorts, might have fried a 79L15 while soldering...


----------



## sachu

aah i feel you buddy..agonizing isn't it..well,  got some case work done. base plate is all drilled and ready.  Front panels will be ordered tomorrow. Boards are populated, just need to check everything a couple more times before i wire it up for testing.


----------



## jdkJake

Looking good ujamerstand! Hopefully your transformer shows up today.


 Hey sachu, mind sharing the part number for those transistor sockets? Thanks!


----------



## ujamerstand

Pulled out the only two components that connects to v- pin of the servo to ground. The short still exist >.>
   
  Good thing is that the short only exist in that segment, which means I could just green wire it, bypassing the short. The Bad thing is I can't spot the short in this small segment... (I now suspect that it is a direct short between the pin and the ground plane, but it is covered up by the IC adapter. -_-)


----------



## limpidglitch

What are the dimensions for the different board segments?
   
  Just thinking ahead


----------



## cobaltmute

Board Dimensions


----------



## runeight

Amp board is 85L x 110W
   
  PS board is 45L x 110W
   
  Heater board is 20L x 110W
   
  Dimensions in mm


----------



## limpidglitch

Thanks.


----------



## jdkJake

Now, THIS is what is known as a First Class Upgrade!
   
  Installed the custom Sumr today. Sweetness:
   

   

   
   
  Plenty of power. Here are the measures:
   
  MOSFETS at 220mV:   38.25V at the regulators
                                     31.35VAC at the secondaries
   
  Heaters at 6.295V:        8.5V at TP3
                                     7.4VAC at the secondaries
   
  I will let it warm up some more and check them again and take some temps. So far, I am really impressed with this part. A luxury item for certain, but, certainly worthy of consideration.
   
  Thanks to BoilermakerFan for the heads-up!


----------



## ujamerstand

Very Cool jake, I've got mine in the mail to day as well. They are certainly very attractive. 
	

	
	
		
		

		
		
	


	




 I've got set back by a short on the V- pin on the servo to ground. Gotta bypass that section somehow. I'm thinking of bending the V- pin on the opamp so that it bypasses the adapter, thus bypassing the short, then solder the .1uF cap as close to the pin as possible, then air wire the rest according to the schematics. Sane plan, no?


----------



## keyid

x2, cant wait but will, oh man another tube binge
  
  Quote: 





stixx said:


> Great!!
> 
> As soon as they pop up in your store I will be ordering...


----------



## jdkJake

Quote: 





ujamerstand said:


> I've got set back by a short on the V- pin on the servo to ground. Gotta bypass that section somehow. I'm thinking of bending the V- pin on the opamp so that it bypasses the adapter, thus bypassing the short, then solder the .1uF cap as close to the pin as possible, then air wire the rest according to the schematics. Sane plan, no?


 

 Do you think the short is under the DIP socket or in the board itself? At this point, odds are pretty good it is not in the board itself.
   
  If you have another socket available, I would probably recommend removing the existing one just to see what might actually be going on. Massive solder blob maybe? Personally, I am not a fan of white wires without knowing why I need them. If you have a solder pump, those DIP packages come out pretty easy as you can really put the heat to them without concern. Even if you have to use a tool of death (aka, pliers) and have to destroy it, it will come out.
   
  Tough call. Ultimately, dealers choice on the solution.


----------



## ujamerstand

no massive solder blob. The resistance between the pins proves that. Its that single pin, or something somewhere on that segment. But since the segment is not very long, and I couldn't spot a single short anywhere, I'm guessing that pin is directly shorted to the ground. Not a fan of pliers of death. I've already scraped off a tiny section of solder mask while using that method. I guess I'll grab a solder pump from the local mom&pop electronic shop in the weekends and see what happens.


----------



## jdkJake

Did you pull C14 yet? Just to take a peek?
   
  How about the 79L15 (V-)? Might want to buzz the 79L15 and make sure there are no shorts between the legs.
   
  EDIT: Nevermind, looks like you already did that.


----------



## ujamerstand

Yeah, pull them both out thinking that it could only be either one or the other. Turns out both were fine. :S Something is shorted to ground, but I just can't find it.
   
  BTW, did Sumr include a hex screw and nut with the transformer?


----------



## jdkJake

Man, that is really strange. The closest ground is the south side of C14. Nowhere near that pin.
   
  Maybe you do have a board defect. I would check the output trace to make sure that is not shorted as well. Like between OUT and R31 and/or R10.


----------



## jdkJake

Quote: 





ujamerstand said:


> BTW, did Sumr include a hex screw and nut with the transformer?


 

 Nope. No hardware to speak of beyond the actual transformer.


----------



## ujamerstand

Yeah, I've already made sure there are no other shorts. I'll have to spend more time to make sure that is the case though. I'll post some pictures after my camera finish charging.


----------



## jdkJake

Okay. I will take a look at them in the morning before work.
   
  This is when an extra unpopulated board would come in handy.


----------



## jdkJake

Update on the Sumr transformer measurements with temps (top center of each heat sink).
   
  

 MOSFETS at 220mV:   38.25V at the regulators

                                    31.35VAC at the secondaries

                                ~44C to 45C

  

 Heaters at 6.295V:        8.5V at TP3

                                    7.4VAC at the secondaries

                                   ~39C

 A little bit hotter than with the Anteks, as expected with the extra voltage being dropped.

  

 Must be some major placebo effect going on. I swear it sounds better.


----------



## ujamerstand

Well, took off the dip socket. Voila, there it was, defect on V- pin. Too late tonight now, but I'll take a knife at it later.


----------



## cfcubed

So I guess mystery solved...  A PCB fab error would be low on ones list of likely faults, but they do happen:
http://www.head-fi.org/forum/thread/386763/how-common-are-pcb-fabrication-errors-i-ve-run-into-my-1st
  Perhaps harder to find/see on a black board, but they sure look pretty so an acceptable trade-off I guess
   
  jdkJake - Seems I always have better luck pulling multilegged beasts using the solder blob method while prying/pulling gently on them.


----------



## jdkJake

Nice work ujamerstand.

 You got that socket out in a hurry! I had a feeling you would not wait until the weekend. Did you use braid and copeous amounts of flux or go medieval on it?


----------



## ujamerstand

I went medieval. I pressed socket pins out from the board, so I didn't damage the board. I've got plenty of these sockets anyways. I'm just thankful the defect isn't on a larger trace segment...


----------



## qusp

yeah Richard does excellent work and I think its excellent that yo guys have come up with a custom spec for the amp from him. all of my final builds get trannies from sumR I actually think his pricing is quite reasonable for the quality of product. for example, my dac I run with 1 x custom TX with single 240v primary with 2 x secondaries of 8v and 16.2v for the stuff like relays, LEDs, USB board and other extraneous control stuff, then the whole dac plus class A IV stage is powered by a 160va TX with single solid core 18AWG primary leadouts on 240v input, 2 x center tapped 25-0-25vac secondaries and 2 x center tapped 45-0-45vac secondaries. fully potted and encapsulated. now that was about $160 for the large TX, but there is effectively 4 quality transformers in there. its a pretty heavy and large TX for a DAC, but it actually saved quite a bit of space compared to separates
   
  this was part of a larger order, we get stung for shipping from canada to AU for such heavy and large orders. love dealing with Richard and even though hes not the cheapest, I think his custom stuff competes with much higher priced iron. shipping stung, was nearly 180aud from memory for shipping the whole order, that shows you how much I like his work.
   
  this amp us looking pretty sexy and the custom specified TX made it even easier. i'll be in for PCB only in a month or 2 as well.
   
  oh yeah I think they sound better too, so I dont think its placebo, if it is its group placebo 
	

	
	
		
		

		
		
	


	




 but then I dont see how its that much of a stretch, its part of the power supply, the line regulation is excellent and the potting/shielding could conceivably lower noise as well as vibration. more marginal improvements in power supply have claimed benefit, so why not.
   
  sorry if the above seems shill-worthy, but lets just say i'm a very happy repeat customer and Richard is a very helpful professional that I like to see the forum support


----------



## jdkJake

Quote: 





cfcubed said:


> jdkJake - Seems I always have better luck pulling multilegged beasts using the solder blob method while prying/pulling gently on them.


 

 I generally like to vacuum up as much solder as possible and then go back with a pick and iron and loosen each leg. That is if I really need to save the part. Otherwise, my general lack of patience has me sacrificing the part and pulling the individual legs out one at a time. Both methods work, just one takes a lot longer. Time == money or some such rationale.
   
  I have not tried the solder blob method. Ideally, I will never have too, but, odds are I will get a chance to in the future.


----------



## jdkJake

Quote: 





qusp said:


> oh yeah I think they sound better too, so I dont think its placebo, if it is its group placebo
> 
> 
> 
> ...


 

 Perhaps there is something there. Aural memory being what it is, everything just seemed tighter if that makes any sense. In any case, I'll take it.
   
  I can post the complete spec sheet, but, I would really like to have Alex chime in his thoughts on the performance aspects before we make a full-fledged recommendation on the part. I know he was looking for around ~36V at the regulators vice 38V. Perhaps we can even consider sizing it smaller, it is that good of a build.
   
   
_*What do you think Alex? Is the currently specified Sumr a keeper? Should we size it smaller? Increase the Rail PS heatsinks by a 1/2 inch just to be safe? *_


----------



## runeight

The voltages you posted are good, just a little high on the pre-reg DC, but as long as the regs run reasonably cool, no problems.
   
  What is your line voltage? If the transformer regulates well then I would say it's a keeper. Other transformers with the same specs but poorer regulation might not do so well.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> Thanks to BoilermakerFan for the heads-up!


 

 Been out of pocket for a few weeks, at least WRT to free time to stay caught up on the forums, but no problem, glad you like them.

  
  Quote: 





jdkjake said:


> Nope. No hardware to speak of beyond the actual transformer.


 

 They are usually sized to accept a 6mm hex bolt.  I bought stainless steel 6mm bolts from Lowe's for mine in the Liquid Gold. 
   


  
  Quote: 





qusp said:


> yeah Richard does excellent work and I think its excellent that yo guys have come up with a custom spec for the amp from him. all of my final builds get trannies from sumR I actually think his pricing is quite reasonable for the quality of product. for example, my dac I run with 1 x custom TX with single 240v primary with 2 x secondaries of 8v and 16.2v for the stuff like relays, LEDs, USB board and other extraneous control stuff, then the whole dac plus class A IV stage is powered by a 160va TX with single solid core 18AWG primary leadouts on 240v input, 2 x center tapped 25-0-25vac secondaries and 2 x center tapped 45-0-45vac secondaries. fully potted and encapsulated. now that was about $160 for the large TX, but there is effectively 4 quality transformers in there. its a pretty heavy and large TX for a DAC, but it actually saved quite a bit of space compared to separates
> 
> this was part of a larger order, we get stung for shipping from canada to AU for such heavy and large orders. love dealing with Richard and even though hes not the cheapest, I think his custom stuff competes with much higher priced iron. shipping stung, was nearly 180aud from memory for shipping the whole order, that shows you how much I like his work.
> 
> ...


 

 No shilling, Richard really goes out of the way to help and I think he bumped those EHHA units up a frame to keep the regulation tighter IIRC.  He's working on 3 customs for me right now and I have 5 more I need to order for other projects.  I know one is going up two sizes to really tighten the regulation since I have the room to fit a big 6" diameter can.  
	

	
	
		
		

		
		
	


	



   
  I like Jack at Electra-Print too, but his bigger VA jobbies are just too costly and you need to set them out in the garage for a week to off-gas the varnish fumes.  Theory holds that toroids will pass all their noise through since they are wide band, but even with X10 home automation protocol sitting on my powerline at 120KHz, I can't hear any noise coming through my SumRs and I do not run filtered IEC inlets, I just use PowerCons.  I found a custom R-core winder, but they don't sell to individuals and they are nowhere near as easy to deal with as Richard.  Great custom R-cores and good service, but so far SumR has come out on top for me and he's so price competitive with the other two (R-cores and E-P) as well.  If I run into a noise issue, I'll go R-cores, but I have a PS Audio Solo now too, so I don't see that being necessary. 
   
   
  And O/T, but my Tang Band drivers showed up yesterday from Planet10 Audio.  
	

	
	
		
		

		
		
	


	




  I haven't even opened the box yet though, been too busy.


----------



## jdkJake

Quote: 





runeight said:


> The voltages you posted are good, just a little high on the pre-reg DC, but as long as the regs run reasonably cool, no problems.
> 
> What is your line voltage? If the transformer regulates well then I would say it's a keeper. Other transformers with the same specs but poorer regulation might not do so well.


 


  Doh! I knew I forgot to measure something.
   
  I have it warming up as we speak. I will take another set of measures and post those later tonight. In the meantime, here is a copy of the test sheet that comes with the transformer. Since it is custom, each is tested individually. Sorry for the poor photo quality, but, my scanner is currently down. Hence, a picture is the best I can do.


----------



## ujamerstand

Mine and yours look exactly the same.


----------



## jdkJake

Quote: 





ujamerstand said:


> Mine and yours look exactly the same.


 


  Hmmm. Maybe it is more of a spec sheet than a test sheet. Looks like I was mistaken.


----------



## Cloud

for transformer requirements are we looking at
   
  120/240 primary, 2x 30V secondary @ 500mA and 2 x 7V at 500mA?


----------



## jdkJake

Okay, amp is all warmed up. Let's try again:
   
  Line Voltage at 122.1VAC
   
  MOSFETS at 220mV:
     Rail PS Secondaries at ~31.2VAC
     Rail PS Regs at ~38.2V
   
  Heaters at 6.295V:
     Heater PS Secondaries at ~7.3VAC
     Heater PS Regs at ~8.4VAC
   
  Sound:
     Tight and tuneful
     Enjoyment factor at ~full tilt JAMMIN'


----------



## jdkJake

Quote: 





cloud said:


> for transformer requirements are we looking at
> 
> 120/240 primary, 2x 30V secondary @ 500mA and 2 x 7V at 500mA?


 

 2x 30V secondary @ 400mA, center tapped (30-0-30)  -- Note: Somewhat dependent upon transformer source
   
  The heater can be wired for 6.3V or 9V, which, will drive the other spec. I built mine for 6.3V, hence the 2x 7V @ 500mA secondaries


----------



## Cloud

Thanks for the quick reply. Seems like i have to import some transformer into Singapore. Those available in Farnell Newark are seriously over spec.
   
  this the closest i can find
   
  Transformer,toroidal,160VA,0-230V pri 50/60Hz,2x0-30V sec
   
  output current is 2.67A. I suppose this is not suitable?
  
  Quote: 





jdkjake said:


> 2x 30V secondary @ 400mA, center tapped (30-0-30)  -- Note: Somewhat dependent upon transformer source
> 
> The heater can be wired for 6.3V or 9V, which, will drive the other spec. I built mine for 6.3V, hence the 2x 7V @ 500mA secondaries


----------



## jdkJake

Quote: 





cloud said:


> Thanks for the quick reply. Seems like i have to import some transformer into Singapore. Those available in Farnell Newark are seriously over spec.
> 
> this the closest i can find
> 
> ...


 
   
  Ah, no.
   
  Far, far too much current. You want something closer to 30VA.


----------



## Cloud

seems like custom is the way to go 
	

	
	
		
		

		
			




  
  Quote: 





jdkjake said:


> Ah, no.
> 
> Far, far too much current. You want something closer to 30VA.


----------



## qusp

Quote: 





boilermakerfan said:


> Been out of pocket for a few weeks, at least WRT to free time to stay caught up on the forums, but no problem, glad you like them.
> 
> 
> 
> ...


 


  you can ask for the mounting hardware when you make the order. extra cost, but bugger all. 
   
  haha yep the quality and looks inspire the want to go all out with them. they look mean. yeah I would like to try Jacks output TX the partial silver is interesting $$$$ but for power TX for the foreseeable future I can see Richard getting all the work. I just save up my orders and get them all at the same time to save on shipping. I definitely recommend against getting the canada post regular post, my first order too over 2 months to arrive, we thought they had gone missing. indeed concerns that are usually voiced WRT toroids dont apply it seems. i've used them with circuits that dont have the best PSRR and no problems as yet.
   
   
  I do think he does test them all for each spec sheet, possibly once a winding is designed its that repeatable that the spec is the same. I know that all of mine usually come with sheets that match performance and pretty difficult to just make up numbers for a batch of custom orders. I suppose he could take a short cut with a large batch, but that doesnt really match with my impression of the man.


----------



## runeight

Quote: 





jdkjake said:


> Okay, amp is all warmed up. Let's try again:
> 
> Line Voltage at 122.1VAC
> 
> ...


 

 These are mostly good numbers. The line voltage is a bit high but so is the input to reg voltage for the rails. This means that there is room for the line voltages to be lower in other situations. But the heater input to reg does not have much room to go lower.
   
  Cloud 30V @500mA or even 600mA would probably be ok depending on other conditions. Higher than this, however, will likely lead to voltages that are too high.


----------



## jdkJake

"Unexpected Distress from my Mistress"
   
  So, after another 3+ hour marathon listening session while paying bills and whatnot last night (total of 8+ hours on the new transformer), I had something quite unusual happen. As I queued up the last song for the evening, a truely evil sound came from the left channel and the power LED's started a random pulsing. You could certainly tell some DC was making it though the left channel into the 650's as I struggled with that damn locking neutrik jack (now I know what I don't like about it) to free the phones. Not sure why I did not go for power first, need to make a mental note to change that behavior.
   
  It was late, so I only took few measures. The problem is confined to the left channel only. Right channel board is fine. With no source input (fully attenuated), everything is more or less okay, but add the least bit of source and the DC offset jumps randomly between 0 and +/-250mV (possibly more, I did not latch it) on the left channel. All the power supplies seem fine, DC output from the rails and heaters was as expected (+/-30 and +6.3), MOSFETS remained biased at 220mV, however, the load at the Rail regulators was at ~28V. Recall I was seeing ~38V prior, so, something is certainly loading down the amp and drawing a ton of current.
   
  It was late, so, I did not do much more besides check out the 650's on my miniMAX (they are fine, took it like a champ). I will take a look at it after work tonight and see if I can figure out what happened. Might be thermal related, but, seems unlikely as I had listened that much (and more) the night before without issue. I guess I will find out tonight.
   
  Any suggestions where to start?


----------



## sachu

can you post readings from all pins of the opamp wrt SG.
   
  Also can you try grounding the inputs to see if the offset goes away.


----------



## runeight

If you can leave the amp on long enough:
   
  Measure the opamp pins as sachu suggested.
   
  Measure the voltage input to regulators. One or both might be toasted.
   
  Don't know what else to suggest until you do more detecitve work.


----------



## runeight

Also, it does seem suspiciously related to a new transformer, but this can also be coincidence.


----------



## runeight

One more thing. Before you test the amp, separate the PS by pulling the jumpers to see if it is working properly.


----------



## jdkJake

Will do. Thanks for the suggestions.

 Gonna have to be tomorrow though. Turns out my social planner has my evening committed.


----------



## WyldRage

I have some questions:
   
  Is it still possible to substitute 6922 and 6H30 for the 6GM8? If that's the case, would jdkJake's tranformer be good for them? Or should I get more current on the 7V secondaries (at least for the 6H30)?


----------



## ujamerstand

For the 6H30, the heater transformer would definitely have to be beefed up, that's for sure. The heatsink on the heater supply would most likely need to be beefed up as well.


----------



## runeight

Quote: 





wyldrage said:


> I have some questions:
> 
> Is it still possible to substitute 6922 and 6H30 for the 6GM8? If that's the case, would jdkJake's tranformer be good for them? Or should I get more current on the 7V secondaries (at least for the 6H30)?


 

 6922 yes, 6H30 no, as ujamerstand noted. The heater supply is just not hefty enough for the 6H30.
   
  However, as you know, you can snap off the heater supplies and use a separate supply. One of the clever features of this design courtesy of the group effort.


----------



## cobaltmute

Just waiting on the SumR transformer...



   
  And yes, I did socket the open loop and closed loop gain resistors as well as the compensation caps. 
	

	
	
		
		

		
			




   
  5600uF on the PS rails.  I was going to go large on the heater supply cap, but it turned out I already had the 2200uF as a Panasonic FM in my parts bin.  Otherwise the heater board will fit a 8600uF FM.


----------



## jdkJake

Looks great cobalt mute. 

 I really like the look of that tube socket. What kind of material is that?


----------



## cobaltmute

It's teflon and something I believe.  They are from here (suggested by johnwmclean earlier in the thread):
Moulded Teflon 9 Pin Noval
   
  I used these ones as Angela didn't want to ship to my address.


----------



## jdkJake

Update: "Unexpected distress..."
   
  So, the detective work starts. I took the right channel out of the equation and am working strictly with the left channel.
   
  The Power Supplies appear to be fine. When disconnected from the AMP, the rail puts out +/-30V. When connected to the amp, same +/-30V output with ~38V on the regulators. Things have changed a bit. With the single channel, I plugged my phones in and got a good dose of full volume (with max attenuation of the input). That was pleasant. Once I pulled the phones, something changed. I plugged them back in and right now, there is nothing coming out save for intermittent distortion (they are still function, I checked on an my receiver). The DC offset is stable (more or less).
   
  Shifting to the TL081, VCC is at +/-15V respectively. Offset N1 and N2 are at -15V, Output settles at -3.6V. Most telling, both input pins measure 0V at this point regardless of attenuation.
   
  The hunt continues...


----------



## runeight

Have you replaced the tube?


----------



## runeight

Also, can you please identify the pins by number on the opamp. Thx.


----------



## jdkJake

runeight said:


> Have you replaced the tube?







 Not yet. Measuring the tube, I have 1V on the cathode, 0V on the grid (with signal applied) and 27V on the plates.


----------



## jdkJake

Quote: 





runeight said:


> Also, can you please identify the pins by number on the opamp. Thx.


 

 1- Offset N1: -15V
  2- IN-: 0V
  3- IN+: 0V
  4- VCC-: -15.2V
  5- Offset N2: -15V
  6- Out: -3.6V
  7- VCC+ 15.2V
  8- NC


----------



## runeight

Thanks. The opamp numbers say that it is servoing properly and you have 0VDC at the output. Waiting to see what you find.


----------



## jdkJake

Well, that's a first. I think I found it.

 Things just were not adding up, so, I bypassed the Alps (mounted on an epsilon27) and all the assorted wiring. I now have signal. Since it is earphone out of an iPod, it sounds like hell, but, it has consistent sound with perfect DC offset control. All other voltages seem fine. 

 Gonna recheck the wiring. I find it hard to believe it is the pot. I suppose you never know.


----------



## stringgz301

I had a similiar problem on my SOHA II.  After a couple of months use started to have noise in one channel.  Drove me crazy tracking it down.  I eventually reflowed the Alps connections to the board and all was good.


----------



## cobaltmute

Quote: 





runeight said:


> Here's a link:
> 
> EHHA Rev A BoM
> 
> Edit: And I forgot to thank jdkJake for the huge effort to finish out the BoM. Thanks!!!!


 

 the PS supply schematic in the BOM linked above and here:
http://www.cavalliaudio.com/ehhaa/main.php?page=schematics/powersupply
   
  have L2R and R6R in a different order from ground to the negative rail. It would seem that the one in the quoted link is correct.
   
  When you use the bottom side trace between the two parts to decide which way to orient the the LED, it means that you get a LED installed backwards if you use the website version.


----------



## runeight

Ah, now I see the problem. The gif schematic is wrong. I'll fix it.


----------



## runeight

Fixed.


----------



## jdkJake

Well my friends, that was certainly one of the most bizarre and unexpected problems I have ever seen.
   
  I air-wired in another Alps and everything was fine. Air-wired the existing Alps (wired directly to the pins, not epsilon27) and everything was fine. Air-wired to the epsilon27 molex pins and the problem was back in the left channel again. Reflowed all pins on the epsilon27 and viola, air wiring to the molex pins works fine. Reinstalled all of the original wiring and everything is fine. Works like a champ. Problem solved.
   
  Then I saw this:
   
  Quote: 





stringgz301 said:


> I had a similiar problem on my SOHA II.  After a couple of months use started to have noise in one channel.  Drove me crazy tracking it down.  I eventually reflowed the Alps connections to the board and all was good.


 
   
  Now I don't feel quite so bad about my apparent cold-solder joint in the most unexpected of places.  
	

	
	
		
		

		
		
	


	




 That was crazy, crazy weird. I certainly would never have suspected an issue on THAT board. The single LEAST complex thing I built for the entire project! Oh well, live and learn. One things for sure, the amp is rugged. I put it though some hell during the debug and it took it like a champ.
   
  In any case, I am back in business. Now to get back to what I was supposed to be doing today which was working on my case. Thanks for all of the help and suggestions! Always most appreciated.


----------



## jdkJake

Quote: 





cobaltmute said:


> the PS supply schematic in the BOM linked above and here:
> http://www.cavalliaudio.com/ehhaa/main.php?page=schematics/powersupply
> 
> have L2R and R6R in a different order from ground to the negative rail. It would seem that the one in the quoted link is correct.
> ...


 

 Aha! Mystery solved.
   
  Nice catch cobaltmute.


----------



## sachu

I think I am just going to modify the values in the heater circuit and only build one of the boards up for 12.6 V and wire it up in series. Just seems to make more sense to me.


----------



## MrSlim

Has anyone compared the SQ of the 6GM8 to the 6922 in the RevA or the original EHHA?


----------



## sachu

i have tried the 6DJ8 in the amp and its alright. 6GM8 sounds better.


----------



## MrSlim

Thanks Sachu, have you thought about what you are going to use for casing?  What's the height measurement to the top of the highest component on the board (the tube?) (with board standoffs)?


----------



## stixx

Heatsinks are 2", so incl stand offs and the pcb itself you are probably looking at around 65mm...
  With tube it will be slightly higher... I seem to recall that someone here wanted to use a 70mm case (sachu?) that just barely would fit.


----------



## sachu

You should be able to fit it in a 3 inch tall par-metal case without too much of a problem if you stick to 6GM8 tubes. Use 5mm standoffs and you should be plenty fine.


----------



## cobaltmute

I believe my stand-offs are 6mm and with the 6n27P, total height is 2 7/8"


----------



## MrSlim

So, is there any consensus on whether E12's are recommended for headphone protection?


----------



## jdkJake

mrslim said:


> So, is there any consensus on whether E12's are recommended for headphone protection?






 I don't believe there is a consensus yet. It will probably remain an optional addition to the build. Just be aware of the potential issues involved by not using it. Also be aware, to do it right, you need two of them, which can drive up the cost of the build significantly.

 FWIW, I am going to use them on my builds. I see it as a value added proposition. I have all the parts, just need the time. Right now, professional sports in Tampa Bay have been providing considerable distraction (shameless plug for Bolts/Rays/Bucs!)


----------



## runeight

Why would you need two?


----------



## johnwmclean

Quote: 





> The ε12 must be powered from the amplifier's main power supply rails. Do not use a separate power supply for this circuit. If your amplifier has a separate power supply for each stereo channel, you should use two ε12 boards. Each one serves one channel only, and is powered the respective supply rails.
> 
> AMB


 
   
   
  Since each channel on the new EHHA revision has it’s own psu you’d need two.


----------



## cobaltmute

I'd use two no matter what due to the fact that the e12 sums the offsets of each channel.  If the rails go south in opposite directions, the e12 will never notice.


----------



## jdkJake

I'm just glad they are small. My selected case is starting to fill up fast!


----------



## cobaltmute

They'll fit in a 12x12 Par Metal.  I've been sizing it out.  It is tight, but they will fit.


----------



## jdkJake

I agree. I took delivery of the par metal 12x12x3 last week. Started the layout and then got disrupted due to that most bizarre cold solder joint issue with my Alps/epsilon combo.

 Started laying out the front panel tonight. I am trying to do something somewhat interesting and hopefully somewhat creative. We shall see.


----------



## runeight

Quote: 





cobaltmute said:


> I'd use two no matter what due to the fact that the e12 sums the offsets of each channel.  If the rails go south in opposite directions, the e12 will never notice.


 

 OK. Definitely a corner case, even if both channels went in opposite directions, but could happen.


----------



## cobaltmute

I know people who have had 2 drives simultaneously fail in RAID 5 arrays, and we just had a case at work where both drives in a RAID 1 array failed at the same time.
   
  It is a corner case, but the cost of a second e12 versus the cost of my HD650s it is what I call insurance.


----------



## jdkJake

I have to agree with cobaltmute, when you start adding up the cost of the headsets (and in the case of the HF-2, availability), it becomes somewhat of a no brainer just to keep things somewhat under control.

 Not to mention the inevitable upgrades that are sure to follow with an amp that can resolve this good. Certainly going further up the Sennheiser, Beyer and Grado lines is now more of a potential option than it might have been before building this amp. It is that good. And then there are those orthos to consider as well ( we hear you sachu ).


----------



## runeight

Sure, I understand. Unusual combinations of events do happen and if the risk is high enough it pays to protect against them.


----------



## jdkJake

Awful quite on the beta front. 
   
  I know cobaltmute is awaiting a transformer, sachu is working the case and ujamerstand working a board trace short/defect.
   
  Myself, I am working the casing. Need to pick up a new drill bit of a particular size and am awaiting a part for the front panel. Hope to have the case work finished by the end of next week if everything arrives as expected. Not sure where studeb or stringgz stand with their case work.
   
  Amp continues to sound excellent. I also just received the parts to socket an swap the open loop/closed loop gain resistors. Looks like I am going to experiment with those settings after all.


----------



## ujamerstand

I've fixed the board defect, but manage to damage a cap while soldering and melted its plastic encasing slightly. Just finished dealing with all the school work, so I hope to have everything running soon.


----------



## sachu

I need to test the boards. Will go over, check if everything is kosher tonight and maybe even bring them up. Heaters are rigged for 12.6V ( should be able to dial it in with 240R, 2k with a 200R trimpot) ..will report back when I test them out.


----------



## ujamerstand

Just wired up the transformer to the boards. The power sections works as intended. No magic smoke. (So far.) Some readings:
   
  10.6V at TP3, 6.4V at heater output.
  rails at +29.4V/ -30.4V and +29.6V/-30.0V 
  before the regulator: (If I'm measuring this correctly) +46.7V/+46.9V and similar readings on the other side.
   
  The power supplies are currently unloaded.


----------



## runeight

Those numbers before the regs are potentially dangerous, but they should pull down when you load the rails. If they get below 40V you're ok.


----------



## ujamerstand

I think so too. Let me wire up the amplifier section and see what happens.


----------



## ujamerstand

Okay, I've wired up the amplifier section, The voltage before the regulators are still above 40V prior to biasing. After biasing the mosfet to 220mV, the voltage before the regulator sits at +/-39.7~39.9VDC. 
   
  DC offset reads at around 0.1mV on one channel, and 4.2mV~ 6.7mV on the other. (This is the board with the defect)


----------



## ujamerstand

Well, I got everything running now. 
	

	
	
		
		

		
		
	


	




 DC-offset on one channel stablizes at 6.3mV, while the other channel has it at less than 1mV. I might want to swap out the opamp or the V- reg to the servo, they might have been damaged while I took them out to figure out whats wrong. 
   
  A short listening session with this amp proves to be quite an enjoyable experience. The EHHA has no problem driving the Hifiman HE-5. On the EHHA rev.A, it is almost as speedy as the STAX SR-404 on exstata, while packing a lot more punch than the 404s. Gotta love planar headphones. 
	

	
	
		
		

		
		
	


	




 It also runs quite warm. I don't think I'll need to turn on the heater in my room during the winter anymore.


----------



## runeight

Great!!! You've probably done this, but make sure to re-bias when the heatsinks get to temperature.


----------



## jdkJake

That's great news ujamerstand!

 FWIW, the DC offset on both of my channels always floats around 0V, so, replacing those parts seems like a logical next step.

 What is your measure at TP3 once under load? Also, what is you AC line measuring on the primaries? Your values seem a touch higher than mine as I usually come in around 38V at the rails with 122VAC on the line.


----------



## runeight

You can always dial up the bias a little, maybe 125mA or whatever you can get within the range of the bias pot. Just watch the temps on O/P devices.
   
  For me, I don't mind running them hot, especially since they are mosfets. But I know that many of you prefer otherwise.
   
  125mA will bump the power dissipation from ~3W to ~3.75W. I don't know how much it will drop the input to regulator voltage.


----------



## ujamerstand

From memory, my measurements at TP3 was around 9.6V. The AC line in my area was 122.8VAC at the time of measurement. That's probably why it's a touch higher than your readings.
  Quote: 





jdkjake said:


> What is your measure at TP3 once under load? Also, what is you AC line measuring on the primaries? Your values seem a touch higher than mine as I usually come in around 38V at the rails with 122VAC on the line.


 

 I've got the bias set at 122mA right now. (From 270mV / 2.2ohm, is this correct?) The pre-reg voltage stabilizes at ~38.6V under the higher current draw. The heatsinks for the output devices gets hot to the touch, I'll have to get a temperature sensor to see if it is less than half of the mosfet's junction temperature. I'll bump the heatsinks to 2.5 inch version otherwise. 
	

	
	
		
		

		
			




  
  Quote: 





runeight said:


> You can always dial up the bias a little, maybe 125mA or whatever you can get within the range of the bias pot. Just watch the temps on O/P devices.
> 
> For me, I don't mind running them hot, especially since they are mosfets. But I know that many of you prefer otherwise.
> 
> 125mA will bump the power dissipation from ~3W to ~3.75W. I don't know how much it will drop the input to regulator voltage.


 
   
  So what do you think? Is the SumR iron recommended? Underspec it a little?


----------



## luvdunhill

what about mounting a pair of chassis mount bridges and then build up a CRC that feeds into C1 (bypass D1-D4)? I think a little more capacitance might be nice to have and this would allow you to deal with your excess voltage. Grab a chassis mount resistor for the "R" as well. Even with doing that, you should consider the LM317HVT version in case something were to go wrong.


----------



## luvdunhill

Quote: 





ujamerstand said:


> to see if it is less than half of the mosfet's junction temperature


 

  
  It doesn't work that way. If the heatsinks were at half the max junction temperature, the device would be dead. For a TO-220 device, you want to be able to keep your finger on the heat sink for at least 3 seconds before having to pull away. This will be about Tj = 80C.


----------



## ujamerstand

I am using LM317HVT. Mouser did not carry lm337hv though, digikey has it, but not in TO220 packaging. Honestly though, the heatsink feels warm to the touch for the regulators, but not hot. If I understand this correctly, the main problem here is with the power dissipation from the high voltage drop, right? Or is there something else I'm missing here? *Edit*: reading the data-sheet on LM337, it does say it has a maximum input voltage at -40V. -_-
  Quote: 





luvdunhill said:


> It doesn't work that way. If the heatsinks were at half the max junction temperature, the device would be dead. For a TO-220 device, you want to be able to keep your finger on the heat sink for at least 3 seconds before having to pull away. This will be about Tj = 80C.


 
   
  Huh. I see. As a rule of thumb, what would be a safe temperature to operate the components in regards to The junction temperature? On amb's beta22 boards and heatsink page he recommends that the junction temperature should never go above 100degrees Celsius for a mosfet with maximum junction temperature at 175 degree Celsius, that's where I got the half the junction temperature thought from.


----------



## ujamerstand

Also, a little off topic here, but how do you calculate the voltage drop over particular values over the CRC regulator? Say if I use the same values for the capacitence in the bijou, 470uF, maybe a 5 ohm resistor, the Vloss would be the current draw of output stage* 5 ohm = ~0.6V?


----------



## runeight

So based on two builds with the SUMR transformer we have high, but not death, input to regulator voltages. What is the primary spec on the transformer? Is it 115V or 120V?


----------



## luvdunhill

The maximum input voltage is usually 37V for most LM3X7 types, unless you shop around. As you suspected, the issue is not voltage drop, maximum input voltage which is just one of the design parameters for the device itself.
   
  100C is too hot for me, and I suspect this number was thrown out as the devices used in the beta22 and sigma22 are especially rugged devices, and the designer was familiar with how hard to push them. I'd recommend 80C for a TO-220.
   
  Your suspicion is correct for the Pi filter. Perhaps check out PSUD2 for modeling this sort of stuff:
   
  http://www.duncanamps.com/psud2/ 
   
  Also, once you have the resistor dropping the correct amount of voltage, make sure you also then calculate a suitable power rating. I'd recommend double the wattage from the calculation that you perform using quiescent current draw (assuming this is a class A amplifier)


----------



## jdkJake

Quote: 





runeight said:


> So based on two builds with the SUMR transformer we have high, but not death, input to regulator voltages. What is the primary spec on the transformer? Is it 115V or 120V?


 


  120VAC


----------



## jdkJake

Quote: 





ujamerstand said:


> I am using LM317HVT. Mouser did not carry lm337hv though, digikey has it, but not in TO220 packaging. Honestly though, the heatsink feels warm to the touch for the regulators, but not hot.


 

 I am running the LM317T Fairchild part from Digikey. It is rated at up to 125C.
   
  Last time I measured:
   
   
 temps (top center of each heat sink).

  

 MOSFETS at 220mV:   38.25V at the regulators

                                    31.35VAC at the secondaries

                                ~44C to 45C

  

 I might bump the MOSFET a bit, but, I am mostly gonna keep an eye on it for now. Down here in Florida, the local power company (Florida Flicker and Light aka Progress Energy) is notorious for playing with the power levels. I suspect they are high right now as we come out of the summer months and peak HVAC demand. I would not be a bit surprised to see 121VAC or less by months end. Just no way to predict it.


----------



## ujamerstand

Thanks for the link, though it should be http://www.duncanamps.com/psud2/index.html 
   
  As for the particular device I used (Fairchild LM337T), the datasheet says the maximum adjustable output voltage is -37V, but it does not mention the maximum input voltage. What IS mentioned is that the maximum voltage differential between Vi and Vo is 40V. Should I really be worried over this?


----------



## jdkJake

Quote: 





jdkjake said:


> I might bump the MOSFET a bit, but, I am mostly gonna keep an eye on it for now. Down here in Florida, the local power company (Florida Flicker and Light aka Progress Energy) is notorious for playing with the power levels. I suspect they are high right now as we come out of the summer months and peak HVAC demand. I would not be a bit surprised to see 121VAC or less by months end. Just no way to predict it.


 

 Case in point, tonight, right now, I am measuring 123.3VAC at the IEC inlet.
   
  MOSFETS are at 220/230mV respectively and input to the regulators is at 38.3V.
   
  Might be totally different in a few hours once peak demand settles down (usually after 11pm EST).


----------



## jdkJake

Quote: 





ujamerstand said:


> As for the particular device I used (Fairchild LM337T), the datasheet says the maximum adjustable output voltage is -37V, but it does not mention the maximum input voltage. What IS mentioned is that the maximum voltage differential between Vi and Vo is 40V. Should I really be worried over this?


 

 I see what you mean, the spec is more concentrated with Input/Output differential:
   
     http://www.fairchildsemi.com/ds/LM/LM317.pdf  
   
  BTW, ujamerstand, are you using the tube LEDs? I am dissipating over 1W per board just to keep those bada-- LEDS putting out 4000mcd a piece.


----------



## ujamerstand

Nope. No pretty leds for me. Realized that I don't like that with my minimax build. More of a natural tube glow kind of guy. 
	

	
	
		
		

		
		
	


	



   
  AC line readings tonight is 124.1VAC.


----------



## jdkJake

Fair enough. They do put off a nice subtle glow when unlit from underneath.
   
  Man, your power is almost as whacked out as ours. Might be easier to just regulate the AC coming in than try to burn off excess.


----------



## runeight

I think we should clarify the regulator discussion a bit.
   
  The max input/output differential on the LM317 is 40V on the National spec. Since we are operating at 30V at the output there is plenty of room.
   
  But there is another reference point, the ADJ pin. The ADJ pin is sitting very close to 30V so that the voltage difference between any two pins on the device never exceeds 40V, in fact given the measurements made so far under load, doesn't ever exceed 10V.
   
  Only these relative voltages matter. There are no absolute voltages on these devices.
   
  However, these conditions only apply once the regulators are at the operating point.
   
  The real problem is on power up. If everything is discharged then the Out and Adj pins of the regs are at 0VDC. The IN swings up quickly possibly to over 40V because the loading takes some time to stabilize. The Out and Adj follow depending on how they are loaded. As long as the relative difference of 40V is not exceeded then the regulator survives.
   
  We should add this means 40V in the forward direction. The regs have diodes to protect against reverse biasing.
   
  It appears that with these transformers and amplifier start up the Out and Adj are following fast enough so that the max differential is not exceeded..
   
  But, as noted, to be safer you can use the HV devices.


----------



## jdkJake

So the main advantage of the HVT parts is the 60V differential tolerance?


----------



## ujamerstand

Right, since the regulators did not blow up on me on the first start up, adj and out are definitely following fast enough. But as a hypothetical situation, where LM337 is knocked out, what would happen to the amplifier? Also, the bias of the amplifier changes as the amp heats up. My pre-reg voltage drops as the bias increases and stabilizes below 40V when the amp finishes warming up. So Vi would be higher than 40V at a cold startup. Are there any situations where the Vout and Vadj are not able to follow Vin fast enough, and the max differential is exceeded?


----------



## runeight

Yes.
   
  Edit: I should always check for new posts!! The yes is in response to jdk's question about the 60V differential.
   
  There might be conditions where these voltages could be exceeded but they wouldn't be unique to this power supply or amp. As I look at the circuit I don't see a condition where this could happen, but start up/shut down conditions can be tricky.
   
  Depends on what you mean by knocked out.
   
  If it is shorted IN to OUT then the negative rail voltage will go to whatever the input to regulator is (approximately). The 79L15 will probably exceed its maximum differential and die. The opamp will have only one rail and will stop working and the output will skew to have a high DC.
   
  If it opens, then the bottom rail will float upwards, all differential voltages in the amp will get smaller, and the O/P DC will skew to the positve rail.
   
  Gents this is not the only split supply that runs at +/-30V using IC regulators. It is a standard regulator configuration.
   
  We cannot guarantee that there will never, ever be a failure, we can just try to keep everything within acceptable envelopes. Many folks who slap together linear regs into a supply like this may not even realize the dynamics of what happens when you turn the bugger on.


----------



## runeight

Having said all of the above, my target was closer to 35-36V as input to regulator. This gives a bit more margin all around. Line voltages are difficult to account for, but the SUMR transformer could be spec'd down just a little bit.


----------



## jdkJake

Okay, so looking back a bit, I found the following:
   
   
     Stringgz is using a 30-0-30 .5A Avel Lindberg and is sitting at 38.2V (unknown line VAC) 
   
     Studeb using a 32-0-32 .8A Antek and is sitting at 39.6V (121.5VAC)
   
     jdkJake was using a 32-0-32 .4A Antek and was sitting ~34V (~121-122VAC)
   
     Ujamerstand and jdkJake are all using the sumR transformer (30-0-30 .4A) and are sitting between ~38V and 39V.
   
  Looks like sachu is going to provide a most interesting contrast. 
   
   
  BTW, if Stringgz and Studeb can chime in on what version of the LM317/337 they are using, I think that would be helpful as well.


----------



## jdkJake

Also, those HVT parts might be hard to come by, especially the LM337.
   
  Digikey has some of the LM317HVT, but none of the LM337HVT. Mouser is out and marks them as obsolete.
   
  Might take a bit to locate a source.


----------



## ujamerstand

Thanks for the explanation. 
	

	
	
		
		

		
		
	


	




 I think I'll keep a few extra components around, and slap on some offset protection on the output of the amp. 
   
  jdkJake: What's your pre-reg voltage at startup? Also, I remember you posted numbers for dc offsets, were they measured during cold startup?


----------



## jdkJake

Not exactly sure on the pre-regs at start up, but I seem to remember somewhere south of 38V (~36V seems to come to mind, but, I am not sure). I will remeasure tomorrow. RIght now, the amp is hot and I am tired.
   
  Yes, I measured all DC offset from cold starts. I performed that particular measure many times over a couple of days.


----------



## runeight

And you may wonder why 35-36V.
   
  Let's say you're running with 120VAC line and it drops 5V to 115VAC. Your secondary will drop by 1/4th of that approximately (120:30). let's say 1.25V. The peak DC will drop by 1.4X this or about 1.8V. This will track approximately to the DC input to reg, If you're running at 35V this will drop to 33.2V. This is more than enough to keep the reg from dropping out.
   
  But remember too that the input to reg voltage is not a flat DC. It has AC ripple on it so even if the average DC is 33.2, the actual voltage is swinging up and down, maybe a half volt or so peak to peak. That's another 250mV drop on the negative swing bringing the instantaneous voltage down to ~33V, bringing it closer to the 30V regulated output. 3V is enough to prevent dropout, but for margin it's seems best not to go lower than this.
   
  Thus, getting this right means having the op point so that it is not too low such that drops in line voltage will cause the regs to drop out and such that higher line voltages will not exceed various maximums.
   
  And this is why the part of this that I hate the most is when you guys start talking about using every transformer in the book. It's almost impossible to make the design able to handle a very wide variety of transformers, particularly if they have widely varying regulation and secondary DCR.


----------



## jdkJake

Thanks for sharing the design insight Alex. Things are much clearer to me now regarding the intended design margins for the Rail PS.
   
  I also understand your frustration with all the part swaps going on. Must be hard to see your design interpreted in so many different ways beyond your control. Kind of like setting your children out into the cold, harsh world. At the end of the day, the implementer is still ultimately the responsible party for a functional (and safe) product that conforms to the design specifications. Please continue to keep us on course, but, realize deviations are inherent in the process due to cost, parts availability and personal preference.
   
  I for one, am still happy with the sumR as currently speced. Remember, I am not done loading it down yet. I still have two epsilon12's to hang off of it. While the draw of those parts is not too significant, they do add additional load to the Rail supplies. Hopefully, I should have those built up later this weekend and will have a better idea of how they effect overall performance of the power subsystem.
   
  Again, please continue to share your design insights and goals for this amp. It makes the entire project far more personal and a very enjoyable and rewarding experience.
   
  We will try not to go too far into the weeds.


----------



## luvdunhill

Quote: 





runeight said:


> And this is why the part of this that I hate the most is when you guys start talking about using every transformer in the book. It's almost impossible to make the design able to handle a very wide variety of transformers, particularly if they have widely varying regulation and secondary DCR.


 


  perhaps putting a CRC on board would help with this... along with clear instructions on how to "set the resistor" it would allow for lots of variance in mains voltage, transformers, etc.


----------



## sachu

well i fired up the heater supply. It slipped my mind that the hammond transformers are rated for 115V primaries. Line AC is at 122.4V.
   
  Regulator input is seeing 21VDC and am getting 12.6V on the output.
   
  The HV transformers are again rated for 115V primaries and secondaries read 32.5VAC. This isn't what i was hoping for as again i thought the primary was 120V windings. Oh well, suffice it to say i will see over 40V on the regultor inputs with the PSU unloaded. Not a good thing IMO. I should have just stuck with my usual Avel dual 28V secondaries transformer. Ah well..we'll see how it does when i bring up the power supplies. Increasing rails PSU caps to 6800uF would help some in dropping the input voltage to the transformers.


----------



## stringgz301

Line voltage is 120.8.  Am using STMicro LM317T for VR+ and On Semi LM337TG for VR-.
  
  Quote: 





jdkjake said:


> Okay, so looking back a bit, I found the following:
> 
> 
> Stringgz is using a 30-0-30 .5A Avel Lindberg and is sitting at 38.2V (unknown line VAC)
> ...


----------



## TimJo

Quote: 





sachu said:


> It slipped my mind that the hammond transformers are rated for 115V primaries. Line AC is at 122.4V.


 

 When I buy Hammond transformers, I get the 300 series with the universal primaries. That way you get 100, 110, and 120 taps. It costs a bit more, but it works well here in the NW, and will keep working if one day I find myself living in other places, which is always a dream.


----------



## runeight

Say, gents, I have been on the road for a bit, but I see that my comment about the transformers didn't reflect as much humor as intended. Sorry about that.
   
  I think we may be over analyzing this problem. The voltages you guys are showing are probably alright. To me adding CRC circuits, etc. is adding more complexity than needed (but thanks for the help Marc 
	

	
	
		
		

		
			





 ).
   
  38-39V on the regs is not a serious problem, just higher than designed.
   
  In the future my guess is that sachu's idea of using the avel 28-0-28 transformer might be the perfect choice or the sumr with a 28-0-28 secondary.


----------



## fishski13

Quote: 





runeight said:


> Say, gents, I have been on the road for a bit, but I see that my comment about the transformers didn't reflect as much humor as intended. Sorry about that.
> 
> I think we may be over analyzing this problem. The voltages you guys are showing are probably alright. To me adding CRC circuits, etc. is adding more complexity than needed (but thanks for the help Marc
> 
> ...


 


  CL-60 thermistors for power-on voltage transients?  larger heatsinks?


----------



## qusp

guys, just as reassurance, when testing out higher voltages on a modified D1 mosfet IV, I have run the LM317/337 at +/-65-67v in and +/-55v out. as Runeight has said, its really only the input/output that matters with these floating regs. they do not care what the voltage is, they only care what they are expected to swallow. you could probably run them at 500v out if the V in was lower than 540v


----------



## stixx

Quote: 





> they do not care what the voltage is, they only care what they are expected to swallow. you could probably run them at 500v out if the V in was lower than 540v


 
  Yep. See them being used in a Maida reg...


----------



## ujamerstand

So as long as the input voltage ramp up slowly so that the regulator don't instantly see the full 40+ volts on startup, we're fine I guess?


----------



## jdkJake

Nice when a plan comes together, even when it is not planned!
   
  Had some time this morning before the game (and during the game once it turned ugly). So, I built and tested a couple of these bad boys:
   

   
  Very nice. Both worked great until I shorted one across U1 6/7 (can you say visible spark!) while performing the setup. Needless to say, torched a transistor with that graceful move. In any case, repairs were made and much more care taken during setup and I was back in business (U1 pin 6 needs a TP for the careless like me on a Sunday afternoon).
   
  In any case, these work great. I socketed R11 and bumped it to 1M, but as I learned, it really does not matter. Since these track the DC offset, they always "do the right thing". With no load, the 1M gave about 6 or 7 seconds of delay. In circuit, upon actual power on, it turns out to be around 20 or 25 seconds as things settle out. Since we are using two, each side come to the party at a different time (usually a couple seconds apart). Kinda weird, but, it works, so, who's complaining. In any case, the stock build (R11 == 475K) should be fine.
   
  Of course everyone wants to know, what's the impact on power?
   
  MOSFETS at ~220mV
  AC at ~122.5VAC (was around 120 earlier today, did I mention the joys of Florida Power?)
  AC on the secondaries: ~30.6VAC
  At the regulator input: ~36.7V
   
  Nice. Moving right into the sweet spot. I can live with this.
   
  Quick road trip tomorrow (damn day job) and them we case this puppy up and call it day.


----------



## runeight

Gents, it seems like there are 3-4 working amps. Are there any listening impressions beyond jdk's. The designer always wants to know how the design is doing.


----------



## cobaltmute

Well Richard has stated that my transformer should ship by Thursday at the latest.  So hopefully by the end of the weekend I'll have comments.


----------



## ujamerstand

Well, I really suck at listening impressions, but I'll give it a try. IMO, the combo between EHHA and the HE-5 provides more impact than 404s and the exstata. I've never found the 404s to be lacking in that department, but the EHHA and the HE-5 has that oomph that makes certain music that much enjoyable to listen to. The sibilance on the HE-5 is at first unbearable, but I don't think this is a problem with the amp, and I got used to it pretty quickly. The amp is also quite speedy. Probably not as fast as the exstata+404 combo, but the HE-5 running on the EHHA is no sleuth either. I really have to clean up the wiring and case it up to reduce the occasional hum; but overall, the amp is very quiet.


----------



## Cloud

was going through EHHA build thread, looking at information for a planned 3 channel active ground build, thinking that a unity gain is required.
   
  then i saw this interesting post by runeight
   
  http://www.head-fi.org/forum/thread/422429/cavalli-ehha-embedded-hybrid-headphone-amp/360#post_5733197
   
  "There is no need to operate the amp in unity gain mode even for the three channel configuration. The ground channel can have its input grounded and then use the same component values as the other two channels. This will ensure that the ground channel can operate at the same speed as the amplifying channels. The amp is unity gain stable with reduced bandwidth as you can see by the very large Cdom caps that Snoopy needed to stablize the SQ response. I think it's better to give the ground channel the same bandwidth as the amp channels."
   
  i suppose this applies to EHHA Rev A as well?
   
  can I know what are the OL gain and CL gain that the beta team are using?


----------



## jdkJake

Quote: 





cloud said:


> can I know what are the OL gain and CL gain that the beta team are using?


 

 So, according to Alex, the 75k resistors on R13/14 provide an OL gain of about 500 with a NFB of ~35db. Using the default 1.2k on R11 should provide a CL of around 9.3.  This should yield a total gain of around 9.2 with 35db NFB.
   
  For my build, I currently have a 1.3k in at R11 for a CL of around 8.7 (total gain of about 8.5 with around 35db NFB). While I think the gain is probably okay for my HD650's, I think it is a bit too much for the Grados, so I am going to socket the resistors and lower the CL a bit. I may also play a bit with the NFB, but, I am pretty happy with the overall sound and might leave that alone.
   
  I am thinking of using a 2.4k at R11 to get a CL of about 5.2. This should yield a total gain of about 5.1 with 35db of NFB. I am thinking this will be about right. Again, I can play with that a bit as the board will be socketed to allow easy change. 
   
  Not sure what the others are using.


----------



## cobaltmute

My intent when I get my transformer, at least for initial try, is to use 10k resistors to set the open loop gain at ~100.  CL gain for initial try will be the default as per the BOM at ~9.3.


----------



## jdkJake

Quote: 





cobaltmute said:


> My intent when I get my transformer, at least for initial try, is to use 10k resistors to set the open loop gain at ~100.  CL gain for initial try will be the default as per the BOM at ~9.3.


 


  Are you trying more to eliminate NFB rather than reduce overall gain? By my calculations, those values should take you to about 8.5 overall but significantly reduce the NFB.


----------



## cobaltmute

Yup.  the goal is low NFB.
   
  I'll play with the CL gain as well, but want to see how the amp sounds to start with.  I'm not a volume hound, so I may do lower gain to get better adjustment on the pot, we'll have to see.
   
  Looks like SumR didn't get my transformer out on time as I didn't get a shipment notice., so it doesn't look like I'll be up and running this weekend.


----------



## jdkJake

Funny, I am probably going to go the opposite way and slowly lower the NFB and raise the CL as I go. I kinda want to shoot for a gain of 5 throughout the whole process. We will see though. I am torn through the promise of wide bandwidth and the seduction of low NFB to bring out the tube.

 In preparation for that experiment, I installed the resistor sockets for R11,13 and 14 today. Man, what an ordeal. Things are quite tight with everything else installed. New and upgraded solder pump got a real workout as well. Nevertheless, I got it done. I would certainly advise others that, if you think you want to play with the gain at all, socket early! 

 I'll get a good listen later tonight and see how she sounds provided I didn't mess anything up through the install effort.


----------



## jdkJake

So, the amp still works. Always a good thing after minor surgery. Casing is coming along as well and the guts are now mounted on the case baseplate, which, makes it easier to work with and move around. A couple case parts are still in paint, so, it will be a day or two before that is finished.
   
  In any case, I gave a good listen with the new resistor gain values last night. Yes, there is slightly (and I mean slightly) more travel to the attenuator pot and that is nice. As for the sound, well, it had most of the character as before but came across slightly washed-out. That might be too strong of a statement, but, probably close to describing it. Perhaps a bit less extended on both ends and the soundstage narrowed a bit as well. I mean, it was still nice, but, some of the original character seemed a bit lost.
   
  So, since I doubled R11 to 2.4k, I figured I would half R13 and R14 to 37.4k and give it a go. Not quite sure where this puts the NFB, but, I am guessing somewhere around 325. If that guess is correct then overall gain for the amp should now be sitting at about a gain of 5.1 or so. Just a quick listen (I will give it a more extensive listen later tonight) and we are back in business. This is a lot closer to what I remember. Everything seems back to life. Things are more extended and the soundstage opened up again. Sweet. I am going to live with these component selections for a bit and see where we go next.  
   
  Alex, do you think my OL guess of 325 is close for 37.4k resistors at R13/14?  (Yes, I know that is a ridiculous value, but it is half of 75 and Mouser had them for 11 cents a piece, so, why not?)


----------



## runeight

Close. Probably mofe like 300. But OL gain also depends on the hfe of the exact transistors you have.


----------



## jdkJake

Quote: 





runeight said:


> Close. Probably mofe like 300. But OL gain also depends on the hfe of the exact transistors you have.


 


  Even better. I was shooting for around ~30db of NFB. Looks like I got close.
   
  Man, this amp sounds sweet! You have set the bar very high Mr. Cavalli! 
   
  IMHO, gonna take some serious mojo (or serious $$$) to better this sound.


----------



## jdkJake

Quote: 





ujamerstand said:


> jdkJake: What's your pre-reg voltage at startup? Also, I remember you posted numbers for dc offsets, were they measured during cold startup?


 
   
  So, I took a couple of measurements over the past few days.
   
  As we have already established, my AC is all over the map. Some days it is close to 120VC and other days it is over 123VAC. Case in point, this morning it was ~120VAC and tonight it is ~123VAC.
   
  In any case, the following is typical: At a ~123VAC at cold start power-up, the initial input to the regulators is ~38.5V. This holds for just a few seconds at which time the voltage drops down to ~35.5V. The value will slowly rise from this point as the MOSFETs warm up and start to stabilize and will end up around ~37.5V. This behavior remains the same regardless of AC input (just down a volt or two in deference to the AC input at that time). So, it looks like with the sumR transformer and two e12's, the power delta at power-on is close, but not at, the max for the 317/337 devices I have installed. Probably best to recommend the HV devices if available to have a bit more margin regardless of transformer. Availability of parts that can accommodate a 50V delta are readily available with limited availability of parts capable of handling a 60V delta. I plan on leaving mine alone for now and will address the issue if and when it becomes a concern (ie., a blown regulator).
   
  BTW, I was going through the thread looking for some unrelated gain information and found that cobaltMute recommended the 50V delta parts during the initial BOM review. Good call cobaltMute. Mental note to self, pay closer attention to the one-off comments, they can be quite prophetic.


----------



## sachu

I am waiting for some 337 devices before i can test the rails again and then bring up the amp boards. The casse is all drilled otu and the panels are due to arrive on thursday. Should be a very busy little bee come next weekend.


----------



## ujamerstand

Quote: 





jdkjake said:


> So, I took a couple of measurements over the past few days.
> 
> As we have already established, my AC is all over the map. Some days it is close to 120VC and other days it is over 123VAC. Case in point, this morning it was ~120VAC and tonight it is ~123VAC.
> 
> ...


 

 Excellent. Thanks for the data!


----------



## runeight

Given these numbers, it isn't really necessary to use the HV devices. The other terminals of the regulators should follow fast enough to keep the various deltas below the 40V max.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> Man, this amp sounds sweet! You have set the bar very high Mr. Cavalli!
> 
> IMHO, gonna take some serious mojo (or serious $$$) to better this sound.


 

 Time to sell off a couple MAX amps, then update your sig again.  
	

	
	
		
		

		
			




   
  It's ok, I sold off my 4 without ever building any of them and still have the original MOSFET-MAX V1.1 prototype board here too...  Need to kit it up and sell it off as well.


----------



## johnwmclean

Quote: 





jdkjake said:


> IMHO, gonna take some serious mojo (or serious $$$) to better this sound.


 

  
  Glad your loving it!
   
  I disagree though, serious $$$ will only blow a hole in your wallet.


----------



## jdkJake

Quote: 





boilermakerfan said:


> Time to sell off a couple MAX amps, then update your sig again.
> 
> 
> 
> ...


 


 What, and break up the band?  
	

	
	
		
		

		
		
	


	



   
  Nah, plenty of room in the family for different perspectives and presentations. At least for now while the family is small.


----------



## jdkJake

Quote: 





johnwmclean said:


> I disagree though, serious $$$ will only blow a hole in your wallet.


 


   I suspect you are spot on with this statement.
   
  Of course this hobby (or is it more of a lifestyle) seems pretty much focused on blowing a hole in my wallet.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> What, and break up the band?
> 
> 
> 
> ...


 

 Well, my band will be all Cavalli amps after the Aikido 24V is kicked out, or rather allocated to console preamp duty.  The Cavalli band will be a power trio initially, but a fourth member will be joining sometime next year.  There is a Pass F5 and a future Octode that will come to play every now and then too, but they will be on speaker duty most of the time.  I can't wait to compare the EHHA RevA with my orthos to the one-off Liquid Lightning design study with my SR-Lambdas, 003s, and custom HE60s once I get those done.  But, as you said, the $$$ for the LL and HE60s far exceeds the EHHA Rev A.


----------



## jdkJake

So, the following are just my tainted observations and opinions. Careful as we all hear things differently and YMMV.
   
  I gave the 37.4k resistors at R13/R14 a good listen the last couple nights. Wow, talk about the bass starting to come out in spades. Deep, powerful, yet always in control. The contrast to the 75k resistors is pretty amazing. From my perspective, the higher NFB has the effect of flattening the frequency response a bit whereas the bass and treble recede a bit in favor of a flatter, perhaps truer frequency response. In this case, lowering the value seems to act as a micro-tone control. At 37.4k, the sound is exciting, big and bold, in all ways, yet still resolving and capable of being delicate when called. I can't believe I am going to say this, but, it might be just a bit too much bass (and I like good bass response). The highs also take on a slightly different characteristic that I cannot describe just yet. Something about them catches me a bit, but, I cannot put my finger on it. Might be something upstream though that I was not hearing before. I need to listen some more with a few different sources.
   
  In any case, swapped in a new set for R13/R14 tonight and will give it a listen. This time, I split the difference between again and went with 56.2k (3/4 of 75k) at R13 and R14 (hey, somebody has to buy these odd resistor sizes to keep them in production  
	

	
	
		
		

		
		
	


	




). I am leaving R11 at 2.4k during all these R13/R14 swaps.
   
  I am going to listen to these for a while and get a better idea of what they do to the sound. Ideally, I hope reduce the bass just a scosh.  I might head south after that as I some 22k (as well as 10k) to try as well just to get an idea of what things sound like down there. The only problem is that this is exactly what I was trying to avoid, endless NFB changes in search of perfection (or at least perfection at that moment). Should have just built a four-deck stepped attenuator with values from ~150k down to 10k and been done with it. Hmmm, now thats an interesting thought....


----------



## runeight

Be careful, it can become an addiction. 
	

	
	
		
		

		
		
	


	



   
  Glad you like it though.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> I am going to listen to these for a while and get a better idea of what they do to the sound. Ideally, I hope reduce the bass just a scosh.  I might head south after that as I some 22k (as well as 10k) to try as well just to get an idea of what things sound like down there. The only problem is that this is exactly what I was trying to avoid, endless NFB changes in search of perfection (or at least perfection at that moment). Should have just built a four-deck stepped attenuator with values from ~150k down to 10k and been done with it. Hmmm, now thats an interesting thought....


 





   
  I think that's a great idea.  Just be sure to match those resistors to 0.05 ohm.


----------



## Cloud

> Should have just built a four-deck stepped attenuator with values from ~150k down to 10k and been done with it. Hmmm, now thats an interesting thought....


 
   
  i have the same thought, just that i was thinking of socketing a trimmer. when i found the value i like, i will replace the trimmer with a resistor. Cheaper this way i think


----------



## jdkJake

A trimmer would work for CL gain at r11, but would not work for OL gain/NFB setting at R13 and R14. Getting two trimmers set to within 1% of each other (which is what you can achieve with resistors) would be pretty difficult. Switching out actual resistors would be far more accurate.

 EDIT: Also, finding a trimmer properly sized that would not get you into trouble will also be a challenge.


----------



## sachu

k..finally got around to bringing up the power supplies on both the channels.
   
  I upped the rail caps to 6800uF. Pre-reg voltage is at 43V unloaded. Not too bad. 
   
  Am not feeling like bringing up the amp boards tonight. The custom panels are coming in tomorrow, so might just do it all at once then.


----------



## Jrossel

Good news!  The boards are in and they look really good.
  Alex and team you have really outdone yourselves.  I will be working on
  kits for the next few weeks and the boards will be available at
  Glassjaraudio.
   
   
  Thanks,
   
  Jeff


----------



## stixx

Great!
   
  That'll be my personal Xmas gift this year...


----------



## BK_856er

My boards are on the way!
    
I ordered all the in-stock Mouser items from the current 1.00j BoM.
    
A number of items were back-ordered, and I'm a bit of a green-horn, so self-identifying appropriate alternatives might be risky.
   
Can anyone help me identify good alternatives for the following?
    
WIMA  MKS2-.1/63/10  Polyester Film Capacitors 63V .1uF 10%
ON Semiconductor  LM317TG  Linear Regulators - Standard 1.5A ADJ 1.2-37V Positive
Fairchild Semiconductor  BC550CBU  Bipolar Small Signal NPN 45V 100mA HFE/800
Nichicon  UPW1H471MHD  50volts 470uF 12.5x20 20% 5LS
Nichicon  UVR1H222MHD  50volts 2200uF 16x35.5 20% 7.5LS  <BOM calls for 10mm lead?>
Nichicon  UVR1H101MPD  50volts 100uF 8x11.5 20% 3.5LS
Nichicon  UVZ1C222MHD  16volts 2200uF 12.5x20 20% 5LS
   
BK


----------



## jdkJake

Welcome to the joys of part hunting. You need to search out and find equivalent parts. Look for electrical first and packaging second. Generally, you will find high rated parts are more available (and expensive). Sometimes, the exact opposite is true. Try to stick to a known brand if at all possible. Quality is as important as price.

  

 For example, from Mouser:

  

 WIMA  MKS2-.1/63/10  Polyester Film Capacitors 63V .1uF 10%

  

    I would suggest the Vishay parts, but they seem to be on backorder as well.

    Did you check TAW Electronics? They usually have WIMA stock on these parts.

    Otherwise, this EPCOS part is available 871-B32529C104K189. Never used them, so, cannot comment on quality

  

 ON Semiconductor  LM317TG  Linear Regulators - Standard 1.5A ADJ 1.2-37V Positive

  

   The Fairchild or STMicro will work fine here: 512-LM317T or 511-LM317T I am using the Fairchild parts for both 317 and 337.

  

 Fairchild Semiconductor  BC550CBU  Bipolar Small Signal NPN 45V 100mA HFE/800

  

    This will work fine: 512-BC550CTA (different delivery packaging Ammo versus bulk)

  

 Nichicon  UPW1H471MHD  50volts 470uF 12.5x20 20% 5LS

 Nichicon  UVR1H222MHD  50volts 2200uF 16x35.5 20% 7.5LS  <BOM calls for 10mm lead?>

 Nichicon  UVR1H101MPD  50volts 100uF 8x11.5 20% 3.5LS

 Nichicon  UVZ1C222MHD  16volts 2200uF 12.5x20 20% 5LS

  

    Mouser now stocks Panasonic FC series (I used FM series where available and FC for the rest, only sourced from Digikey).

    Unfortunately, the 470uf parts are backordered as well.

       667-EEU-FC1H471

       667-EEC-FC1H222

       667-EEU-FC1H101

       667-EEU-FC1C222

       

 Spend some time researching the different parts that are available and why they differ. You will learn a lot that will help you in future builds. We are fortunate the internet makes this easy to do.


----------



## cobaltmute

My transformer came in this week instead of last week.  I should have power up in the next few days.


----------



## TheShaman

Quote:


jrossel said:


> Good news!  The boards are in and they look really good.
> Alex and team you have really outdone yourselves.  I will be working on
> kits for the next few weeks and the boards will be available at
> Glassjaraudio.
> ...


   

 That'll make a great Christmas present indeed!
  Jeff, please let us know when you have an estimate of pricing.
   
  Would the EHHA RevA serve dual-duty as a preamp as well? Any changes necessary?


----------



## BK_856er

Quote: 





jdkjake said:


> Welcome to the joys of part hunting. You need to search out and find equivalent parts. Look for electrical first and packaging second. Generally, you will find high rated parts are more available (and expensive). Sometimes, the exact opposite is true. Try to stick to a known brand if at all possible. Quality is as important as price.
> 
> ...
> 
> ...


 


 Thanks, jk, I appreciate it.  I started to dig into spec sheets/sources/brands yesterday and became pretty overwhelmed with detail and differentiating important from unimportant for a given location.  I'll have another go at it with the leads you mention.  The learning ramp is a steep one.  I definitely don't want to cheap out anywhere and I'm in no real hurry.  From earlier builds, I have given up on trying to collect everything from just one or two orders - too much pressure.  I sourced lead bender tools from TAW last week and had a great experience, so I tried them for the WIMA part....35,000 in stock and 4pcs are on my way gratis...great company to deal with!
   
  BK


----------



## jdkJake

Quote: 





bk_856er said:


> Thanks, jk, I appreciate it.  ...
> I sourced lead bender tools from TAW last week and had a great experience, so I tried them for the WIMA part....35,000 in stock and 4pcs are on my way gratis...great company to deal with!


 


  Your welcome.
   
  I too have had a great experience with TAW. Very, very easy to work with and always looking to make things easier and more affordable (i.e. Shipping).


----------



## jdkJake

Finally, the casework is done!! (Warning, FAR too many photos coming):
   
  Wanted to do something a bit more special with this one. I wanted to give the chance for the tubes to shine (literally) without being too overt. Overall, I am pleased with the way it turned out.
   
  This is a Par-Metal 12x12x3 case:
   
   

   
  Kind of  tight, so I went vertical with the e12's:
   

   
  Spartan back-panel (Thanks to Horio for the idea to back mount the neutriks, I think they look far better that way):
   

   
  And the front, featuring "windows" for the tubes with a play on the topology of the amp itself:
   

   
  Changed out the LED color, these are actually purple and only 2200mcd to dim it down a bit for night time use. Just enough light:
   

   
  Still sounds better than it looks!


----------



## sachu

nicely done Jk..looks like we both had the same idea with regards to the windows.. 
	

	
	
		
		

		
		
	


	



   
  Now you only need to transition over to orthos to make the journey complete lol


----------



## cobaltmute

That's a three inch high ParMetal isn't it? How is the heat? I was going to go the same way bit am worried about heat buildup in the case.


----------



## ujamerstand

The engravings on the windows look great! Congrats on casing it up! Actually, what are you using to side mount the e12s?


----------



## fishski13

looks awesome Jake!  is that the black painted finish Par-Metal offers, or did you paint it?


----------



## jdkJake

Thanks for the kind words guys!
  
  Quote: 





sachu said:


> nicely done Jk..looks like we both had the same idea with regards to the windows..
> 
> 
> 
> ...


 

 That's cool. I look forward to seeing your take on the concept. You know what they say about great minds... 
	

	
	
		
		

		
		
	


	




  
  Quote: 





cobaltmute said:


> That's a three inch high ParMetal isn't it? How is the heat? I was going to go the same way bit am worried about heat buildup in the case.


 

 Yes, it is the three inch high case. I have not run it long enough to get a good idea on the heat build up, but, I will for sure find out. I used quarter inch standoffs, so, there is plenty of space from the top of the heatsinks to the top of the case. I also drilled two extra strips of ventilation holes in the center of the case. My goal was to not only help vent the heat from the e12's (which get surprisingly hot) but also the inside MOSFET's and Rail PS sinks. I will try to get some thermal readings soonest. BTW, I tried a "free-style" technique on those holes using the laser on my drill press. Let's just say a punch technique for started holes is far more accurate. Good thing it is on the bottom and out of sight.
   
  Quote: 





ujamerstand said:


> The engravings on the windows look great! Congrats on casing it up! Actually, what are you using to side mount the e12s?


 
   
  Thanks. I can only claim partial credit for the engravings. The design is mine, but, I used lasercut to do the actual engraving. 
   
  The e12's have an asymetrical hole pattern for standoffs, so, only two of the standoff holes will allow back-to-back mounting of the two boards. The aluminum standoffs I had on hand were too big in diameter such that they touched some traces/solder joints, so I went with these from RatShack:
   
     http://www.radioshack.com/product/index.jsp?productId=2102860
   
  Still had to trim them to fit flush, but, no chance of shorting anything. To secure to the bottom of the case, I went primitive and used two holes to the side of each standoff and a pair of black nylon tie-wraps. Not as good as a screw mount, but, it is also not going anywhere.

  
  Quote: 





fishski13 said:


> looks awesome Jake!  is that the black painted finish Par-Metal offers, or did you paint it?


 

 I painted it. I went with the black anodized case hoping it would look good enough as unpainted would dissipate heat the best, but, once I saw it, I knew it needed a paint job to look even remotely professional. So, my fav, Black Satin Krylon makes yet another appearance. I should buy stock in that company.
   
  Parting pic for the evening...


----------



## BK_856er

jk, that parting pic is outstanding.
   
  Got my boards from glassjar today - living in the same town has its benefits.  Boards look great.
   
  Ordered all Panasonic FM (and one FC) electrolytic caps and also the other bits mouser couldn't cover.
   
  Put an inquiry into SumR for the RC0050 051 8.
   
  Getting closer....
   
  BK


----------



## jdkJake

Thanks. Be sure to read back into the thread a bit regarding the transformer. You might want to dial it back a bit, but, you would be breaking new ground, so, be sure to understand the change and why you you would be making it (if you indeed make a change).

 Glad to hear your part hunting went well.


----------



## BK_856er

Quote: 





jdkjake said:


> Thanks. Be sure to read back into the thread a bit regarding the transformer. You might want to dial it back a bit, but, you would be breaking new ground, so, be sure to understand the change and why you you would be making it (if you indeed make a change).
> 
> Glad to hear your part hunting went well.


 

 I read back a bit again on the transformer - thanks for pointing that out.  My line AC is rock solid year-round at 115V, so maybe I'm in good shape with the assigned SumR?  My readback indicated that maybe a 28-0-28 version SumR would be ideal, or perhaps a different brand altogether.  Any consensus at this point in time?
   
  BK


----------



## runeight

If your line voltage really is 115 and generally stays in that vicinity then the 30V SUMR is probably the right choice.


----------



## sachu

Yeah..even the stock hammonds will work great.


----------



## BoilermakerFan

Quote: 





sachu said:


> Yeah..even the stock hammonds will work great.


 


  But do they hum along with your music?


----------



## sachu

I will know possbly by tonight if there are any noise problems but Having used hammond transformers in other builds I have'nt noticed this yet.


----------



## sachu

Hmm
   
  brought up both the boards and no dice.
   
  Output shows 0 DC offset.
   
  However, i am not able to bias up the output devices at all. Full turn towards either end of the trimpot gave me nothing.
   
  Rails are steady at +/-30V.
   
  Is the Vbe multiplier not setup correctly for the BJT version perhaps?


----------



## runeight

What value did you use for R17?


----------



## sachu

3.9k


----------



## runeight

Well, the BJT Vbe circuit was set up nominally for MJE243/253 devices. If you are using these guys you should be able to get something to show. But if you're using other BJTs then it's hard to know.


----------



## sachu

Am using the Toshiba 2SC2232/968 devices..I do have the MJEs somewhere here..but it'd be a shame not to be able to run the toshibas in this amp. 
   
  I know gurubhai is using them successfully in his EHHA1 BJT build.


----------



## runeight

Try reducing the 3k9 to 3k3. Then set the trimpot to its maximum resistance before firing up. This adjustment is non-linear so even 600R reduction can make a huge difference.


----------



## runeight

And, of course, are the pinouts correct?


----------



## sachu

Right..except don't think i have any 3.3k resistors lying around.
   
  Okay..switched to the MJE devicces..I read 0.5V between the test pointss and Out.
   
  However, positive rail is getting slammed is being pulled down to 1V. Positive regulator gets real hot.
  Negative rail is steady on both boards.
   
  Output DC Offset is reading ~ -27V wrt SG.
   
  Its on both boards.
   
  **facepalm**  How could i forget..indeed the pinouts are reversed on the toshibas..
  Will switch the back..but will need to figure out why the positive rail is getting hit so bad. .


----------



## sachu

okay..switched the toshibas around..the half way mark on the trimpots nearly is perfect to bias them up. Glad i installed the transistor sockets..so much easier to these things.
   
  Everything is kosher now.
   
  However strange thing about the MJE devices..once i grounded the input the DC offset on the out put went away. With the toshibas even with the inputs ungrounded DC offset is at 0V.


----------



## sachu

One more thing..mounting the toshibas bring in another problem..the heatsinks are no longer on board and can't be socketed into the board.


----------



## runeight

If the Toshibas have exacty the opposite pinouts from the MJEs they should work in the mosfet positions. If so, then all you might need to do is spread the pins apart a bit.


----------



## sachu

^^..yup
   
  that should work. Will need to move the sockets to the mosfet pin positions.


----------



## runeight

In the meantime, can you tell us if it makes any noise?


----------



## cobaltmute

I just fully powered up my first board.  BJT (mounted on the MOSFET pads).  Power up was smooth.  Initial bias was .9V.  Was able to trim it out to 1V with a number of turns of the trimpot.  My first test of offset showed 0.01mV.
   
  Other board will be powered up on Wednesday and hopefully I'll get sound after I fix the e12 I smoked during setup.
   
  I should say that with 5600uF on each rail on the PS, the time to discharge is surprisingly long.  The functioning e12 doesn't release immediately when the power goes done so I'm going to have to test to see what power off behavior is.


----------



## sachu

nearly done with the wiring. Just power supply wiring and some clean up to go and the amp will be cased up. Will get to it tomorrow.
   
  Sachu


----------



## Cloud

can we use 2SC2238/2SA968?
   
  i quite like the sound when used in my jisbos


----------



## sachu

Yes..those are the ones I like too and apparentlly so does cobalmute. 
  Both our builds use these toshibas.


----------



## Cloud

thanks sachu. may I know which transistor socket are you using?
   
  and where did you source your toshiba from? are those from ebay trustable?


----------



## jdkJake

cobaltmute said:


> I should say that with 5600uF on each rail on the PS, the time to discharge is surprisingly long.  The functioning e12 doesn't release immediately when the power goes done so I'm going to have to test to see what power off behavior is.






 I am sure you already know this, but, the AMB website has a suggested wiring scheme to immediately release the relay by putting one of the DC supply lines through a pole of your power on switch. I did not use this technique, but, it would eliminate thump, which is slightly present upon amp power down.


----------



## cobaltmute

sachu said:


> Yes..those are the ones I like too and apparentlly so does cobalmute.
> 
> 
> 
> ...





I was going to use those Toshiba's but I'm using a set of Rohm's instead


----------



## cobaltmute

jdkjake said:


> I am sure you already know this, but, the AMB website has a suggested wiring scheme to immediately release the relay by putting one of the DC supply lines through a pole of your power on switch. I did not use this technique, but, it would eliminate thump, which is slightly present upon amp power down.




Yeah it was pretty quick to figure out that is what I needed to do. Only thing is to figure out where to put another relay as I'm using a e24 to switch power for my amp


----------



## jdkJake

Quote: 





cobaltmute said:


> That's a three inch high ParMetal isn't it? How is the heat? I was going to go the same way bit am worried about heat buildup in the case.


 


  Just an update. I ran last night for almost two hours with the chassis instrumented to monitor thermal build-up. I placed the thermocouple in what I suspect to be the worst place for heat build up. You can confirm where that point is just by feeling around the top of the case. Recall the picture of my inside mounting, from back to front, I placed the thermocouple right in front of the dual e12's and behind the star ground terminal strip at a height equal to the top of the sidemounted e12 PCB. This is perhaps slightly higher than the heatsinks but underneath the top panel such that is was not touching the top panel.
   
  Room temp was ~77 or 78F (~25C) but varies a bit as the HVAC is set at 76F, but, all the electronics, computers and lights make it vary a fair amount. After about an hour or so, the internal temp at that point was pretty solid at 55C (~131F). Toasty, but not too unreasonable. The top of the case is hot, but, you can hold your hand on it without discomfort.
   
  If this case temp causes concern, then I would suggest those who use the 12x12x3 Par Metal have them run another row of vent slots right down the middle of the top panel. That should provide more than enough convection cooling for the case. I am  considering having that done as I have some painting errors I need to correct on that part anyway.


----------



## sachu

Quote: 





cloud said:


> thanks sachu. may I know which transistor socket are you using?
> 
> and where did you source your toshiba from? are those from ebay trustable?


 


 I bought mine from MCM. Everything points to it being genuine. Also regal sent me a set ex gratis.
  Here are the transistor sockets..ignore the image they have on the  site for it. They got the wrong one up.
  
  Quote: 





cobaltmute said:


> I was going to use those Toshiba's but I'm using a set of Rohm's instead


 


  Rohms??


----------



## cobaltmute

Quote: 





sachu said:


> Rohms??


 


  Yup - 2SD1763 and 2SB1186  from a Kumisa build I was trying.  Had them left on the bench so decided to use them rather than order "new".


----------



## sachu

nice..how would you characterize the audible differences between the Rohms and the toshibas?
  AM al up for rolling some different complimentary pairs on this amp.


----------



## stixx

Quote: 





> Here are the transistor sockets..ignore the image they have on the  site for it. They got the wrong one up.


 
  Err, hope you don't mind asking... how did you mount the sockets to the board when contacts on the Molex sockets are inline...?
  I looked them up... also found MillMax sockets, but different pitch.


----------



## sachu

umm these are not for the To-92 packages..these are for the output To-220 devices.
   
  digikey hsa a pic of these sockets here.


----------



## cobaltmute

Quote: 





sachu said:


> nice..how would you characterize the audible differences between the Rohms and the toshibas?
> AM al up for rolling some different complimentary pairs on this amp.


 

 I've never heard the Toshiba's and my listening so far with the Rohm's has been spotty as I'm having oscillation problems with the Kumisa.


----------



## sachu

oh..ok. 
   
  Yeah i rolled a bunch of output devices when i had the stacker and the 2232/968s sounded the most neutral and to my liking. This is the first time am using them in the EHHA so I am hoping it'll sound better than the mosfet version.


----------



## cobaltmute

Quote: 





sachu said:


> oh..ok.
> 
> Yeah i rolled a bunch of output devices when i had the stacker and the 2232/968s sounded the most neutral and to my liking. This is the first time am using them in the EHHA so I am hoping it'll sound better than the mosfet version.


 


  From every description I've read the 2232/968's seem to be of the sound signature I'd like, so I would like to hear them in an amp.  My issue was sourcing them and ensuring that they were good.
   
  There may be a meet in the Toronto area in late November, so I'm hoping that happens so I get to hear ujamerstand's EHHA which is a mosfet build and compare the differences.


----------



## sachu

Aye...I have only used the mosfet version for the last 2 years...don't have any of the ones i built since the first one, but I have a very good idea of how the mosfet amp sounds for me to compare to the BJT version. I hope to have some initial impressions tonight


----------



## sachu

Cased up, powered..Listening


----------



## jdkJake

Quote: 





sachu said:


> I bought mine from MCM. Everything points to it being genuine. Also regal sent me a set ex gratis.


 

 Sachu,
   
  Do the ones you got from MCM look like this:
   

   
  Or more like this?:


----------



## sachu

Will put up a better pic later.


----------



## jdkJake

*Sweet!*
   
  Very, VERY Nice Sachu. What does the engraving at the bottom reference?


----------



## sachu

I just wanted to personalize my builds..


----------



## jdkJake

Very Cool. Adds tons of personality.
   
  Those are some huge conical bumpers you got there as well!


----------



## sachu

Yeah..Justin at  headamp hooked me up with those. I love them.
   
  The amp sounds pretty rough right now..Needs to burn in. Atleast a good 2-3 hours.  The tubes are NOS as well . So far its decent but not up to the level I expect this amp to be performing at.


----------



## jdkJake

What gain settings are you going with?


----------



## sachu

using standard of 11 so far..I have them socketed. This works fine with the LCD-2..but for the wharfedale I still need to crank it to over 12 o clock to similar listening levels as on the LCD-2  ( 9 o clock for the lcd-2)


----------



## BoilermakerFan

Looks great Saachi.  I've heard of a tuning fork before, but never a tuning spoon.
   
  The closest MOSFET to the 2238/968 are the Toshiba 2SJ313/2SK2013s.


----------



## ujamerstand

Those mosfets are mighty expansive. >.>


----------



## BoilermakerFan

Quote: 





ujamerstand said:


> Those mosfets are mighty expansive. >.>


 


  I paid $2.50 or $5 each.  I forget.  Brought in 30 pairs from China through a trusted source on diyAudio.  Also brought in 120 pairs of the SJ74/SK170s for all the amps and phono stages, upgrades for my Yammie receiver and a few other projects.  Both sets of Toshibas will be going in all my Cavalli Audio amps except the Liquid Lightning. 
   
  Saachi had a quad, but let the fairies out of one set.


----------



## ujamerstand

Ah diya, what a great place. You can always find a lot of good parts for sale in the swap section.


----------



## BoilermakerFan

Quote: 





ujamerstand said:


> Ah diya, what a great place.


 
  Yep, I'm a fanatic sponsor over there and I'll have an article or two in the newsletter within the year.


----------



## cobaltmute

Last Proto up and running, and in need of a permenant case.
   

  Still need to get the e12s into the circuit and I will be good. "Cased" it up this way to see what the fit would be like on a 12"x12" base.
   
  Have a hum issue I need to track down in the right channel, goes away as the volume goes up.
   
  Have Tons of detail, gobs of bass.  Little too bright in the high end for my personal taste, but am going to wait and see what happens with regards to that as things burn in.  I also have the OL gain to play with (as well as possibly changing output transistors).


----------



## BK_856er

Quote: 





runeight said:


> If your line voltage really is 115 and generally stays in that vicinity then the 30V SUMR is probably the right choice.


 


 Thanks for the confirmation.  Heard back from Richard today and ordered the 30V SumR p/n RC0050 051 8.
   
  BK


----------



## jdkJake

Looking good cobaltmute.

 You might want to try the alternate grounding scheme Alex posted on his site. I had a slight hum until I went with that scheme.

 I also think you will find the OL gain setting has a pretty dramatic effect on the overall sound. You can really tame the highs and reduce the bass by adding more NFB to the mix. I am finding less NFB makes for an exciting sound, but, not always the most compelling. The 'as built' settings are pretty much spot on for a good overall balance.


----------



## cobaltmute

The thing about the hum is that it is inversely dependent to the volume.  Pot all the way down and the hum is loud.  Gets quieter until about the 10:30 position where it "clicks" off - it doesn't just fade away.
   
  I've got 10K resistors in for setting the OL gain right now.  
	

	
	
		
		

		
		
	


	




  An exciting sound that some would like, but I prefer a bit more laid back presentation..


----------



## Beefy

Could it be oscillating depending on source impedance?


----------



## cobaltmute

Possibly.  But I don't have a scope and it sounds like a power supply kind of hum.


----------



## ujamerstand

Try rerouting your wiring, I've got the same problem with my set up, but it could be solved by shifting the input wiring and stuff.


----------



## jdkJake

cobaltmute said:


> The thing about the hum is that it is inversely dependent to the volume.  Pot all the way down and the hum is loud.  Gets quieter until about the 10:30 position where it "clicks" off - it doesn't just fade away.
> 
> 
> 
> ...







 That is strange. I would still try the alternate star ground configuration. It ties the input to star ground rather than the output.

 Based upon what I have been trying, I suspect 10k is exciting indeed! I also prefer something a bit more controlled.


----------



## studeb

Just some notes on the recent conversations you guys have had
   
  i built mine with the stock gain, which i find to be high with all the headphones i have tried - HD600, V6 and K240 sextetts. My source is P-3A dac > B1 buffer > EHHA Rev A.
   
  That initial brightness will go away, and then you will love the amp. When i powered mine up the first time it was excessively bright. i left mine on overnight, and the next day it was much better.
   
  edi: i went straight for the alternate grounding scheme, the amp is dead quiet.
   
  i am having issues with time at home and with my sources, but i will try to put together a proper listening impression this week, and answer the question about which 3X7 i used.


----------



## cobaltmute

The hum is not the usual background hum that you'd get in an amp.  Once you get past the 11 o'clock position, the amp is dead silent, until the last 5 degress of pot rotation where the hum comes back.  At nothing and at full volume the hum is exactly the same volume and "sound".  It is a 60/120Hz tone.

 Moving the ground from the PS supply end of the amp board to the input side made no difference.

 I should note that ground from the pot goes to the star ground and not the amp boards.  This is because I'm using the e27 board for the pot and it uses a common ground for left and right.  If I attached the ground from it to the boards, it becomes the star ground.

 So my grounding in words:
 Input Left Ground > Pot Board > Star Ground
 Input Right Ground > Pot Board > Star Ground
 Left Heater Ground > Star Ground
 Right Heater Ground > Star Ground
 Left PS Ground > Star Ground
 Right PS Ground > Star Ground
 Left AMP Ground (near output terminal) > Star Ground
 Right AMP SG > Star Ground.
   
  Left channel has no issues.

 Any further advice as to where to look?

 I did change the OL gain resistors to 75K. Did tame tame  the "loose" sound and put the sound into a place I'm really liking, but it didn't solve the hum problem.


----------



## cobaltmute

Oh, and I should note - changing the channels from the pot did not solve anything, nor did switching the sides of the tubes.


----------



## ujamerstand

I have similar symptoms. Hum would be present in both channels on the output when I have the volume all the way down. As I increase the volume the hum would disappear. Then I noticed that the hum would disappear if I move some wirings to a different place.


----------



## jdkJake

Okay, that's something different. When I was using the e27, I did not tie it to star ground. I wired it straight through (both signal and ground) and tied the amp input itself to star ground. 



 I tied the heater PS, rail PS, Amp inputs as well as the neutrik output jack ground to star ground.



 Sound like the problem occurs in the log taper portion of the pot. Strange indeed.

 EDIT: I used a separate terminal block to represent star ground and wired the above mentioned points to this point. It was also isolated from chassis ground.


----------



## jdkJake

BTW, not sure if your were reading the posts on some of my issues with the e27. I ended up having a cold solder joint that had a dramatic effect on the amp itself. Long story short, I went back and reflowed the alps inputs on the e27 using a healthy dose of flux to insure a good flow. Cleared up my issue fine.

 I reflowed the molex connectors as well, but that was not the issue, it was the alps connections.


----------



## runeight

Quote: 





cobaltmute said:


> The hum is not the usual background hum that you'd get in an amp.  Once you get past the 11 o'clock position, the amp is dead silent, until the last 5 degress of pot rotation where the hum comes back.  At nothing and at full volume the hum is exactly the same volume and "sound".  It is a 60/120Hz tone.
> 
> Moving the ground from the PS supply end of the amp board to the input side made no difference.
> 
> ...


 
   
  So the question is, where can this kind of hum come from? If it's not buzz then it's not coming from the PS circuitry. If it's just plain 60Hz hum then it has to be coming from the AC components somehow.
   
  I guess you don't have a scope?


----------



## sachu

Am not having any of these hum issues  and am using open hammond transformers!! No siree..no uber expensive "encapsulated" SUMR transformers for me.


----------



## cfcubed

My guess as well, if not source impedance maybe headphone impedance.  Perhaps not related to this amp, but I'd oscillation much like you describe (e.g. vol positions) w/my ß22, only w/250R DT880s, before I added Zobel network.   I'm going to strike this... It's only AFAIR, was a while ago & might not be entirely accurate.  Also that ß22 problem, unique to use w/my 2003 DT880s, was more of a squeal than a hum.   But it did come & go with vol positions like you describe.       Carry on
  Quote: 





beefy said:


> Could it be oscillating depending on source impedance?


----------



## sachu

I am using an ALps pot too but it is shunt modded. The noise figures go up arguably in the shunt configuration (going by posts by someone else on some other forum about this), so I only hear some noise as i cross the 3 o clock position. But up to that point the amp is dead silent. 
   
  Could it just be that your amp is still uncased and is on a wooden board that you are getting this noise? Once you put it in a metal chassis and ground that to AC safety ground and SG to the same Safety ground (through a ground loop brekaer if need be) perhaps you might not hear this noise. 
   
  edit: And Chris..what are you doing still using a B22..When are you building an EHHA buddy


----------



## cfcubed

Ha ha... I said I'd do an EHHA _someday_, and when I do so I'll probably grab a kit from Jeff.  Have a little CK²III and that 4-ch ß22 / Buffalo32 combo in the works first.
  And we know the ß22 is quite an amp as well... Brunes, blonds & redheads my friend
  
  Quote: 





sachu said:


> edit: And Chris..what are you doing still using a B22..When are you building an EHHA buddy


----------



## sachu

Never said it wasn't 
	

	
	
		
		

		
		
	


	



   
  And you still haven't built up that buffallo and B22?? that reminds me..you were going to splpit that and offer me the buffalo wasn't it


----------



## cfcubed

We can PM, but ran into a problematic board that beat me, an ever-growing honey-do list & found the audio stuff I already have good enough for me.
  But now I 'm trying to get all that gear together for Nov. NYC area meet.  We'll see.  Besides IIRC there's a new Buffalo in town for you to consider
  Quote: 





sachu said:


> And you still haven't built up that buffallo and B22?? that reminds me..you were going to splpit that and offer me the buffalo wasn't it


----------



## cobaltmute

Quote: 





runeight said:


> So the question is, where can this kind of hum come from? If it's not buzz then it's not coming from the PS circuitry. If it's just plain 60Hz hum then it has to be coming from the AC components somehow.
> 
> I guess you don't have a scope?


 
   
  Unfortunately, no scope.  Never quite justified the price versus a project I was working on.
  
  Quote: 





cfcubed said:


> My guess as well, if not source impedance maybe headphone impedance.  Perhaps not related to this amp, but I'd oscillation much like you describe (e.g. vol positions) w/my ß22, only w/250R DT880s, before I added Zobel network.   I'm going to strike this... It's only AFAIR, was a while ago & might not be entirely accurate.  Also that ß22 problem, unique to use w/my 2003 DT880s, was more of a squeal than a hum.   But it did come & go with vol positions like you describe.       Carry on


 
   
  This is a good lead.  300Ω HD650 has the issue.  33Ω Cheap Senn earbuds exhibit a low level uniform hum through the whole volume range.
   
  I think my next course of action will be:
   
  1 - take the board out and clean it again and just do a check for any shoddy joints.  As jdkjake said, I'll check my joints on the e27 as well (although I think I'm going to make a board to replace it that has split grounds).
  2 - ensure all my wiring is good, including grounds.
  3 - if still having an issue, add a zobel.


----------



## cobaltmute

I got lazy:
   

   
  and I have a dead quiet amp now.
   
  0.015µF in series with about a 5Ω resistor.  No idea if those values are great, but it was the best I had in the boxes on my bench.


----------



## jdkJake

_"It's not a habit, it's cool, I feel alive..."_
   
  I knew I should never have put those sockets into the amp to play with the gain. 
	

	
	
		
		

		
			




   
  After much experimenting and endless resistor swaps, I have come almost full circle. I am back to the original 75K at R13 and R14 to bring the NFB setting back to the value Alex intended it to be. This setting brings back the sound I found so compelling in the first place. Don't get me wrong, by reducing the NFB, you can make the amp loose as a goose and as "exciting" as you want, but, to these ears anyway, the most balanced, accurate sound is at the values Alex originally specified (no surprise there I suppose). 
   
  I did reduce the closed loop gain a bit. I am using 1.8K at R11 for what I calculate to be an overall gain of ~6.5. This gives a bit more play on the pot for my grados and puts the HD650 right into the sweet spot with plenty of room for obscene amounts of volume. Nice.
   
  In any case, time to step back from the churn, button it up and just enjoy the amp. Really, I mean it this time...


----------



## jdkJake

Quote: 





cobaltmute said:


> ...and I have a dead quiet amp now...


 


  Are you going to leave it like that or try to track down the source of the problem?


----------



## Cloud

is this a ground loop breaker between PS ground and amp ground?
   
  Quote: 





cobaltmute said:


> I got lazy:
> 
> 
> 
> ...


----------



## fishski13

sachu,
  beautiful build.  good to hear that the Hammond EI are free of noise.


----------



## Lil' Knight

Is it a must to have the e12 in the amp?
   
  Also, I have a spare Avel +/-30v 80a left from my B22 build. Is it ok to use it with the EHHA?


----------



## jdkJake

Quote: 





cloud said:


> is this a ground loop breaker between PS ground and amp ground?


 


   No, it is a Zobel network between signal output and ground.


----------



## jdkJake

Quote: 





lil' knight said:


> Is it a must to have the e12 in the amp?
> 
> Also, I have a spare Avel +/-30v 80a left from my B22 build. Is it ok to use it with the EHHA?


 


  No, the e12s (plural, you would need two) are an optional component. They protect your headphones from excessive DC offset upon power-up as well if something should happen to the amp during use (unexpected circuit/part failure).
   
   
  Is that transformer REALLY 80A? Even 800mA would be too much for this build.


----------



## cobaltmute

Quote: 





jdkjake said:


> Are you going to leave it like that or try to track down the source of the problem?


 

  
  I'll spend some time to try and track it down.  I'll still do the steps that I said, but if it doesn't work at least I know I have a solution.


----------



## runeight

If the zobel is from O/P to ground that particular solution shouldn't really work. The roll off frequency of the zobel should be above the audio band. If it isn't, then you loose HF response. If it takes out 60Hz or 120Hz then it is killing freqs in the audio spectrum. Something else must be taking place, even with the zobel in place, that is not related to the behavior of the zobel. That combination that you've chosen might even put a bump on the HF end of the spectrum.
   
  I don't think that this addition can really be fixing the problem unless it is fixing a grounding problem or something similar.


----------



## Lil' Knight

Yeah, I still have a couple of E12s left from the last build. Just wondering if it's a must to have them.

 My bad, the traffo is actually 80VA.
  
  Quote: 





jdkjake said:


> No, the e12s (plural, you would need two) are an optional component. They protect your headphones from excessive DC offset upon power-up as well if something should happen to the amp during use (unexpected circuit/part failure).
> 
> 
> Is that transformer REALLY 80A? Even 800mA would be too much for this build.


----------



## jdkJake

Personal preference on the e12's. Then again, if you already have them, why not, right?

 80VA is too much. Ideally, you are probably looking for something around 30VA, perhaps a bit higher depending upon the manufacturer. Unless you are going balanced or dual mono with a four board solution. Then it might be okay, still a bit high, but closer in the ball park. What is the part number?


----------



## Lil' Knight

How about a 50VA one? It's the Avel-Lindberg Y23 series that's recommended on the o22's web page. Since I'll order the boards from GlassJar, I might ask them if they still have a 50VA one on hands.


----------



## sachu

That works...but get the 25+25 secondary one instead of the 30+30 if your AC mains are steady at 120V. If its at 115VAC then you can go for the 30+30 transformer.


----------



## jdkJake

IMHO, I still believe that is too much transformer. The 50VA Avel puts out 830mA. Less than half of that is more than plenty. 
   
  If you are going to buy an Avel, why not use the 30VA Y236107 that Alex recommends on the EHHA Rev. A BOM? As Sachu points out, you can probably get by with the 25-0-25 part as well (6106).
   
  Unless you are building a four board solution, 30VA is plenty, especially for the Avel product.
   
   
  EDIT: Just to be clear, since you have referenced the sigma22 web site, this amp has it's own built in power supplies. Unlike the original EHHA, there is no sigma22 required for the Rev A version.


----------



## BoilermakerFan

Or bump the PS caps up a bit and just have more power on tap, run bigger 2-1/2" heat sinks and bias up to 200mA.  
	

	
	
		
		

		
			




   
  A couple of resistors may have to go from 1/8W to 1/4W or 1/4W to 1/2W, but not a big deal to have more reserves if you're driving orthos.


----------



## Lil' Knight

Quote: 





jdkjake said:


> EDIT: Just to be clear, since you have referenced the sigma22 web site, this amp has it's own built in power supplies. Unlike the original EHHA, there is no sigma22 required for the Rev A version.


 
  Of course I know this.
   
  Just mentioned about the 50VA because GlassJar has it and if it works, I'll take it along with the boards.


----------



## sachu

I do have 6800uF caps on mine, that helps to bring down the pre-reg voltage down by a volt or two. But still with 30-0-30 transformer with a 115V primary winding will show close to 46V pre-reg unloaded. With the hammonds that are rated at 28-0-28, a 115V primary winding and 6800uF rail caps i see 42V pre-reg unloaded. I need to take some measurements with the PSU under load. Will do that shortly and post them.


----------



## jdkJake

No slight intended Lil Knight, just wanted to be sure we were on the same page. 
   
  For reference, recall in much earlier posts (~#854) that stringgz is using the 30VA Avel:
   
   Stringgz is using a 30-0-30 .5A Avel Lindberg and is sitting at 38.2V (120.8VAC line in)
   
  I guess it all depends on how close to the standard build you want to go with and what your line VAC is expected to be.


----------



## egotrip

Little bit OffTopic.
  Has anyone speaked to Jeff? (mail etc.)
  trying to contact him regarding an order.
   
  back OnTopic.
  This amp looks promesing. Maybe i'll order a kit when I am done with my oncoming amp.


----------



## arteom

Any chance we can get a comparison in sound quality of the Rev A and original version of the EHHA?


----------



## johnwmclean

Quote: 





egotrip said:


> Little bit OffTopic.
> Has anyone speaked to Jeff? (mail etc.)
> trying to contact him regarding an order.


 

  I contacted him a couple of days ago, he may take a while to get back to you when he’s busy.


----------



## Lil' Knight

Quote: 





egotrip said:


> Little bit OffTopic.
> Has anyone speaked to Jeff? (mail etc.)
> trying to contact him regarding an order.


 
  I ordered the boards from him like 4 or 5 days ago but haven't got shipping notice from him yet. Busy as usual.


----------



## Lil' Knight

Quote: 





jdkjake said:


> I guess it all depends on how close to the standard build you want to go with and what your line VAC is expected to be.


 
  Oh I forgot to mention, my AC mains is 230V.


----------



## jdkJake

Is your line voltage closer to 230 or 240VAC?


----------



## Lil' Knight

Much closer to 230vac.


----------



## stixx

Quote: 





> I ordered the boards from him like 4 or 5 days ago but haven't got shipping notice from him yet. Busy as usual.


 
  Ordered mine about a week ago and got a shipping notice yesterday (to Germany).
  So he's busy fulfilling all the wishes of them impatient buyers... 
	

	
	
		
		

		
		
	


	



   
   
   
  .


----------



## egotrip

I order Saturday 2 weeks ago.
  I guess he is waiting for all the parts for my kit, but a simple answer to my mails would be great.


----------



## stixx

It is quite usual that small business's like Glassjaraudio (probably just Jeff himself) do have to do
  everything by themselves... like ordering, sorting, packing, shipping and so on. Then they simply
  have no time left to also answer ALL the emails...


----------



## runeight

This is true for Jeff and GlassJar. I've worked with him for many years and he is indeed just one guy doing everything.
   
  So how many amps are actually working now without problems?


----------



## ujamerstand

Most people from the prototyping team I guess. Cobaltmute and I are experiencing hum, but I don't consider mine an issue, as mine is more about cable management than anything else.


----------



## jdkJake

Mine is now fully buttoned up and working well. No hum at all. My initial hum was cured going to the alternate ground scheme back when I was running the Antek transformers. I never had any issues with the sumR part with regards to hum, so, I suspect ujamerstand and cobaltmute will eventually isolate their hum issues.

 Not sure where studeb or stringgz stand with regards to their amps. I know they are up and running, but, I do not know the status of their casing efforts. Sachu appears to be finished and working as well, although he took down his casing pictures, so, he must be up to something interesting.


----------



## runeight

OK. Just trying to be sure that the new board/kit buyers will be free from problems. At least any problems inherent to the circuitry.


----------



## stringgz301

Mine is all boxed up with no issues.  I had a fair amount of noise until it was in the case (random crackling, picking up the neighbor's circular saw) but it is dead-silent now.  I used the alternate grounding scheme.  
   
  Awesome amp.  It's going to the ChiUnify get together this weekend.  We'll see what others think.


----------



## BK_856er

One of my final items to procure are tube sockets.  For some socket types I have the option of silver or gold plating.  Does it matter, or is one type preferred for this application?  My current top pick is the teflon composite material with gold contacts.
   
  BK


----------



## BoilermakerFan

Quote: 





bk_856er said:


> One of my final items to procure are tube sockets.  For some socket types I have the option of silver or gold plating.  Does it matter, or is one type preferred for this application?  My current top pick is the teflon composite material with gold contacts.
> 
> BK


 


  It doesn't really matter too much.  Silver is cheaper but it does tarnish over time, but IMHO it's not a big deal as a couple of cycles removing and reinserting the tube wears off the tarnish.  I tend to pick gold for tube sockets and things that don't see as much swapping of parts or cables.


----------



## BK_856er

Quote: 





boilermakerfan said:


> It doesn't really matter too much.  Silver is cheaper but it does tarnish over time, but IMHO it's not a big deal as a couple of cycles removing and reinserting the tube wears off the tarnish.  I tend to pick gold for tube sockets and things that don't see as much swapping of parts or cables.


 


   Thanks.  Gold it is then.  Also opted for a nice TKD potentiometer.  Glad that I stopped keeping track of expenses!
   
  BK


----------



## stringgz301

Made what I hope are the final tweaks to my Rev A:
   
  - socketed R11 and increased it to 1.8k - definitely more play on the pot now
  - received and installed the FPE panel and installed the LED's
  - painted the case.  can't really see it in the picture but it's a very cool blue flake
   
  It's now buttoned up, and hopefully will stay that way.
   
  I've also tried a little tube rolling.  Mainly been listening with Tele's: very clear, clean, and firm.  Tried some holland ones (small halo getter) and they were pleasant but less defined.  Instrument location was more approximate.  Also ordered a pair of russian 6n27p Reflektors of eBay but one tube is flaky (DC offset never settles down) so haven't been able to listen to them.  Anyone have a Reflektor I can borrow?
   
  This has been a fun project.  Much more wiring than anything I've done before (CTH, SOHAII), but one listen makes it all worth it.


----------



## sachu

Very  cool build Stringz aka melodiouspunk
   
  I concur with your views on the teles vis a vis the hollands..the teles are the best of the 6GM8 variant i have tried in this amp and i've tried a  fair few.
  Shame about the 6N27..was looking forward to some impressions on that tube.


----------



## stringgz301

By the way, a big thank you to Ujamerstand for creating the logo.  It turned out very well


----------



## jdkJake

Very Nice Stringgz! 
   
  That is quite the pairing you have there. Very nice indeed.


----------



## ujamerstand

Nice build stringgz! I'm glad it was useful.


----------



## jdkJake

Quote: 





stringgz301 said:


> - socketed R11 and increased it to 1.8k - definitely more play on the pot now


 

 So stringgz, what do you think of the sound with the HF-2's at 1.8k?


----------



## stringgz301

I think R11=1.8k gives a great sound and more than enough play it the pot to be useable.  I had it at the ChiUnifi meet yesterday and many people commented on the transparent, solid, and musical sound of the amp.  I also had a chance to listen to the HD-800, LCD2, HE6, and K702 through the amp and it drove all of them extremely well (would probably raise the gain for the HE6 but it still sounded great).


----------



## herro

I'm considering trying this build. What are the smallest enclosure dimensions I could get away with while still having ideal spacing between components? I am considering the HWCHAS series (http://www.hammondmfg.com/HWCHAS.htm) or the 1441 (http://www.hammondmfg.com/dwg20CWW.htm). What sizes of these two would be appropriate. Any other similar recommendations would be appreciated (preferably <$150).


----------



## stringgz301

Size wise the 13 x 10 might work and the larger one would definitely work.  The bigger issue is ventilation.  This baby puts out lots of heat so you're going to needs a bunch of holes on the top and bottom.  Not sure you want to do that to either case you showed.


----------



## Lil' Knight

I'm wondering if it's OK to use a high input impedance pot for this amp? I have a spare 250k DACT in the drawer from my last project. Would be great if I could use it.


----------



## jdkJake

Quote: 





stringgz301 said:


> I think R11=1.8k gives a great sound and more than enough play it the pot to be useable.  I had it at the ChiUnifi meet yesterday and many people commented on the transparent, solid, and musical sound of the amp.  I also had a chance to listen to the HD-800, LCD2, HE6, and K702 through the amp and it drove all of them extremely well (would probably raise the gain for the HE6 but it still sounded great).


 


  So, I've been back listening to the HF-2's lately. Man, they really fit this amp well! I ended up reducing to 1.5k at R11 (still 75k at R13/14). I think I like this as the best balance between top-end clarity and bass presence yet still gives you some travel on the pot.
   
  If you feel adventurous and do not mind losing some of the low end presence, 2.1k at R11 is pretty interesting with the HF-2, especially with acoustic and/or acoustic guitar-based music. Not sure I would live there full time, but, it is a nice place to visit.


----------



## jdkJake

Quote: 





lil' knight said:


> I'm wondering if it's OK to use a high input impedance pot for this amp? I have a spare 250k DACT in the drawer from my last project. Would be great if I could use it.


 

 So, not sure about the 250k pot, but, I asked the following question of Alex during the BOM/schematic checkout phase of this project:
   
   What size pot are you recommending? 50k? 100k?
   
  Answer:
   
   50k would best. 100k would be ok.


----------



## stixx

My boards arrived today...
   
  They do look very good... excellent work Alex!
  And thanks Jeff for fast delivery to Germany!
   
  Untíl you guys see the first european build it'll probably be a few months... too many other things to finish.
  Finally have to get my Aikido cased up (80% finished), but then I have my Mouser order ready to be sent...






 ??


----------



## jdkJake

Casing update.
   
  I received another top plate for the Par Metal 12x12x3 case. This one has an extra row of slots right down the middle (I also painted it correctly this time):
   

   
  This extra set of slots has helped with heat build up in the center of the case. I posted this to show it as an option to consider as well as to let you know that Par Metal did not charge for the extra row of slots, which, was a nice surprise. Ideally, I would have the bottom plate redone as well, but, there is too much work involved at this point in the project. For those going forward, it is certainly an option to consider.
   
  All packaged up, screwed down tight and still sounding great! Hopefully this keeps me from playing with the gain/NFB anymore....


----------



## ujamerstand

Definitely a nicer finish then anodized black. A lot of people had problems with their customized services, I'm glad you didn't have any trouble.


----------



## jdkJake

Yeah, the anodized black is a great undercoat, but, really shows the marks if you are not careful with it (which, I wasn't). 

I think this case mod was so simple, there was little room for failure. Still, I had my fingers crossed.


----------



## arteom

Anyway this build can be modified to run speakers? I am stuck between this and the original EHHA, really wanted something that could run a pair of efficient speakers.


----------



## johnwmclean

Quote: 





arteom said:


> Anyway this build can be modified to run speakers? I am stuck between this and the original EHHA, really wanted something that could run a pair of efficient speakers.


 


  The original EHHA is better designed for speaker use.


----------



## godog

can it be used as a pre-amp?


----------



## qusp

yes


----------



## Alcaudon

Does anyone have any info on the status of the kits that Jeff is preparing?
   
  Thanks!


----------



## keyid

got a reply yesterday says very soon, looking for enclosures and pots atm


----------



## Alcaudon

Quote: 





keyid said:


> got a reply yesterday says very soon, looking for enclosures and pots atm


 

 I'll have to be patient then.Many Thanks!!!


----------



## gurubhai

The parts bom mentions heater transformer as 500mA. Is that correct ?
   
  I thought we needed atleast 700 mA for a pair of 6GM8s.


----------



## jdkJake

That rating is per board. You need a total of 1A for both channels with each channel being supported by 500mA.


----------



## jdkJake

BTW, it is specified per channel in case you want to build a three or four channel build.

Just in case you were wondering.


----------



## gurubhai

But the PS trafo is also mentioned as 500mA. I don't think that is per channel, is it?


----------



## jdkJake

No. Each of the PS channels require a minimum of 200mA (30-0-30) for a total of 400mA for two channels.The Avel recommended on the BOM happens to be a stock item available at 500mA, which, will provide enough power for two channels.
   
  Transformer recommendation has been an interesting side conversation on this thread. There are numerous ways one can procede. I recommend you read through the back threads a bit to get a better perspective. That being said, the part listed on the BOM was recommended by Alex. You should be perfectly fine using that part.


----------



## ujamerstand

jake is right. Each channel of the amp requires 200mA. OTOH, each 6GM8 needs 330mA on the heater, which is not supplied by the amp psu, but the DC heater psu. Different power supplies.


----------



## gurubhai

I did read the whole thread, unfortunately I wasn't paying attention to the heater requirements when I was purchasing trafos & bought the ones as specified by bom.
  My boards are ready & test fine. I was just gonna connect both the boards when I realized that the tubes would need higher current 
	

	
	
		
		

		
		
	


	



   
  Could have been listening to the amp by this time.
  Ah ok, will get the new trafo tomorrow.


----------



## holland

You need to be cognizant of the fact that DC heaters are used.  There's current and voltage loss for rectification.  In short, take the 330mA and double it (more like 1.5x-1.8x, but double is safe).  The actual amount differs based on the type of rectification utilized (half, full, or bridge).  The EHHA, and most things, are bridge, which is about 1.7-1.8x your DC current draw.  AC heaters can really be dead on with the tube spec, allowing for tube variation.
   
  This really applies to any rectification.  I think builders should measure AC current draw (post xformer) to confirm current draw and secondary voltages are within your xformer's spec.  Overloading your xformer may not work for the long term, along with other detriments.  That's more general commentary than EHHA specific.
   
  Depending on the amp design, I usually take the transistor bias and double it to determine the xformer load, allowing room for additional draw from other pieces.  It only becomes a larger issue when space is a commodity, and what transformers are available off the shelf.  Such as a jump from 50VA to 100VA is a good sized chunk of space, but a jump from 25VA to 50VA is not as significant in size.


----------



## jdkJake

Quote: 





gurubhai said:


> I did read the whole thread, unfortunately I wasn't paying attention to the heater requirements when I was purchasing trafos & bought the ones as specified by bom.
> My boards are ready & test fine. I was just gonna connect both the boards when I realized that the tubes would need higher current
> 
> 
> ...


 
   
  Higher current and different voltage.
   
  Okay, so, the BOM does not specify heater transformers. This is because there are two distinct ways to construct the heater DC supplies. They can be built for either 7V or 9V transformers.
   
  Which build did you go forward with? Did you use 1N5822 or UF4002 rectifiers?
   
  This will drive your choice of transformers.


----------



## jdkJake

To be clear, the amp requires two (2) transformers.
   
  1 for the amplifier power supply (30-0-30 at 400mA)
  1 for the tube heater power supply (7V or 9V at 1mA depending upon rectifier choice)
   
  Do not be confused by multi-secondary transformers such as the sumR which contain both power sources in a single package.


----------



## runeight

Gents, there is inconsistency in the BoM. The rail transformer is specified for both channels but the heater transformer is specified for one board. Thanks for catching this.
   
  My apologies for anyone who bought the wrong heater transformer.
   
  But, what do you all think the best way to spec these would be? For each board or for two boards?


----------



## holland

Quote: 





runeight said:


> But, what do you all think the best way to spec these would be? For each board or for two boards?


 
   
  per board is probably best for the various configs.


----------



## stixx

What about overspec'cing the transformers to reduce heat...?
  I am usually overspeccing transformers in a tube amp at least double since I dislike transformers running at 100°F plus...
  I know it has been dealt with here before... but when going custom wound, couldn't a 28-0-28 at 800mA be used? Same for the heater transformer...
   
  My Aikido parafeed headphone amp uses all regulated supplies (Salas HV shunt reg) and two 80VA toroids to generate HV and 6.3V. Of course I am using RC circuits to tailor voltages going in the regulators, and transformers get barely warm to the touch after extended listening periods.


----------



## jdkJake

runeight said:


> But, what do you all think the best way to spec these would be? For each board or for two boards?






Since the vast majority will build two channel systems, you should probably specify both.

Something like:

30-0-30 at 400mA (200mA per channel)
7VAC at 1A (500mA per channel)
9VAC at 1A (500mA per channel)


----------



## holland

Quote: 





stixx said:


> What about overspec'cing the transformers to reduce heat...?
> I am usually overspeccing transformers in a tube amp at least double since I dislike transformers running at 100°F plus...
> I know it has been dealt with here before... but when going custom wound, couldn't a 28-0-28 at 800mA be used? Same for the heater transformer...
> 
> My Aikido parafeed headphone amp uses all regulated supplies (Salas HV shunt reg) and two 80VA toroids to generate HV and 6.3V. Of course I am using RC circuits to tailor voltages going in the regulators, and transformers get barely warm to the touch after extended listening periods.


 
   
  There's no free lunch, but I tend to err on overspec by a tad if possible.  Overspec means more voltage, which means the regulators need to burn more, which means heat there instead of on the xformer.  Is it better?  I can't really comment as I don't know.


----------



## runeight

MHO is that it is not necessarily good to over spec the transformers for the reason holland stated. You have to burn the power somewhere and the higher the secondary voltage the more power you burn. For me, the most optimal situation is transformers that hit the design spec as best as possible because this should burn the least power in both the devices and the transformer.
   
  But, this is diy and we all have different ways we like to do our builds.


----------



## stixx

Quote: 





> which means the regulators need to burn more, which means heat there instead of on the xformer.


 
   
   
  Quote: 





> that hit the design spec as best as possible because this should burn the least power in both the devices and the transformer.


 
   
   
  Yes, good point. I guess the situation with the EHHA RevA is somewhat different than my other stuff since voltage goes directly into the reg... and current demands in general are lower.
   
  Thanks gents!


----------



## BoilermakerFan

Well, if you're doing a MOSFET build, you can dial up the bias a bit to pull the power to the FETs.  I'd rather burn the extra power at the FETs and bring them up to about 50degC.  Then the regulator and trafo can be cooler and quieter.


----------



## jdkJake

Even with the stock bias the FET's are coming in around 44 to 47C. I don't think there is much room to bring them up to 50C and still dissipate another 400mA. 

MHO, given all the back and forth on transformers and regulator input voltage discussed earlier in this thread, I think Alex is spot on (and being very polite) in stating the need to stick as close as possible to the design margins. Heck the sumR is built to spec and is at the high edge of those margins (abet with some very high wall outlet output of ~123VAC).

Now if you want to go that way with the Antek parts, that is another discussion all together....


----------



## runeight

Gents, I have posted a new BoM with more accurate transformer specs.


----------



## BoilermakerFan

jdkjake said:


> AEven with the stock bias the FET's are coming in around 44 to 47C. I don't think there is much room to bring them up to 50C and still dissipate another 400mA.
> 
> MHO, given all the back and forth on transformers and regulator input voltage discussed earlier in this thread, I think Alex is spot on (and being very polite) in stating the need to stick as close as possible to the design margins. Heck the sumR is built to spec and is at the high edge of those margins (abet with some very high wall outlet output of ~123VAC).
> 
> Now if you want to go that way with the Antek parts, that is another discussion all together....








Is that on 2" high sinks? 

I agree it's better to stay closer to spec, but IMHO FETs sound better at 50-55degC. On a similar design, I'm able to run 230mA through IRF510s on 2-1/2" sinks and they stay at 52degC. 

Now, there is no way I will run my BJTs that hot, but for MOSFETs, no problem.


----------



## jdkJake

2" sinks, 100mA (220mV) bias measured at room temp, 25C (77F) at the top of the heatsink, not the junction.


----------



## cobaltmute

Quote: 





runeight said:


> Quote:
> 
> 
> 
> ...


 

 This was posted on 11/3 and I have finally had a chance to get back to the amp and track the hum down.
   
  Moving the grounds around on my ground point moved the hum between channels, but never completely eliminated it.
   
  Removing the pot from the loop (input + input ground direct to the amp boards) removed the hum totally. This is using the two channel main wiring.
   
  I've got the e27 board on my RK7, which combines the ground at the pot making a second "star-ground" so I think this is where the ground hum was coming from.  As I prefer the board over soldering direct to the pot, I'm just going to make myself a new board that doesn't combine the grounds.


----------



## jdkJake

That's great news cobaltmute. I was wondering how your project was progressing now that I am pretty sure you are seeing far less bike time these days. 

Have you come to any decisions on casing?


----------



## cobaltmute

At -22C with the wind chill today, I'm not thinking about biking.  Although I did see a guy running to work.
   
  Still thinking about the 12x12x3 Par Metal in black for the case.  Need to get my e12s operational again and then I'll start really focusing on it.


----------



## runeight

cobaltmute, I lived in northern New Hampshire for a few years. I remember the cold. Then I moved to Arizona.


----------



## cobaltmute

Quote: 





runeight said:


> cobaltmute, I lived in northern New Hampshire for a few years. I remember the cold. Then I moved to Arizona.


 


  I grew up in Edmonton.  I remember walking to junior high school in -40C *before* wind chill.  Now I get slush instead of snow.  I miss cruchy snow.


----------



## studeb

another ex-edmontonian
   
  i  miss the seasons, and the clear skies in the winter
   
  don't miss the spring slush though

  
  Quote: 





cobaltmute said:


> I grew up in Edmonton.  I remember walking to junior high school in -40C *before* wind chill.  Now I get slush instead of snow.  I miss cruchy snow.


----------



## jdkJake

Quick question for Alex regarding OL gain.
   
  Earlier in the the thread you indicated that with 75k resistors at R13/R14 the OL would be about 500 (give or take depending upon hfe of the output devices). You also indicated that with resistors around ~37.5k the OL would be about 300.
   
  Given this working range, can one assume a somewhat linear interpolation of the interium values? For example, would a value in the middle of that range, say around ~56k come in with an OL gain of around 400?
   
  Thanks!


----------



## holland

Quote: 





jdkjake said:


> Quick question for Alex regarding OL gain.
> 
> Earlier in the the thread you indicated that with 75k resistors at R13/R14 the OL would be about 500 (give or take depending upon hfe of the output devices). You also indicated that with resistors around ~37.5k the OL would be about 300.
> 
> ...


 

 EHHA I Open Loop Gain


----------



## jdkJake

Thanks Holland, however, the Rev A, while very close to the original, does not quite follow that same table (reference posts #540 and #872 of this thread).
   
  I kind of want to get a positive confirmation from Alex on this one.


----------



## runeight

33k - 250
  47k - 330
  56k - 375
  62k - 400
  68k - 435
  75k - 468
   
  With all the caveats.


----------



## jdkJake

Thank you Alex!


----------



## jdkJake

So, I wanted to confirm the Open Loop Gain with Alex (Thanks again Alex!) to aid in my basic understanding of Open/Closed Loop gain and Negative Feedback. I used the data he provided to update the reference table I used for when I went through my various combinations of OL/CL gain changes.
   
  I learned a LOT doing this activity. Not just in terms of listening experience, but, from learning the math that backs what I was hearing. So, I figured I'd share the table I was using to guide my listening experiments. The values have been updated to match what Alex provided.
   
  Remember, at best, this is for relative comparisons and general guidelines. YMMV based upon your build and selection of output devices.
   
   
  Standard value of R11:
   
                     R11:    1.2k 
                       Beta:   0.11 
R13/R14     OL      CL      NFB 
  33k              250     9.00   28.88 
  47k              330     9.08   31.21 
  56k              375     9.11   32.29 
  62k              400     9.12   32.84 
  68k              435     9.14   33.55 
  75k*            468     9.15   34.18     <= standard value for R13/R14*
   
   
  Extrapolated for some common values of R11 (CL gain from ~9 down to ~5):
   
                R11:     1.2k                    1.5k                 1.8k                   2.1k                  2.4k 
                Beta:     0.11                   0.13                 0.15                  0.17                  0.19 
R13/R14  OL    CL     NFB        CL     NFB       CL      NFB       CL      NFB       CL      NFB
  33k          250   9.00   28.88     7.44   30.53     6.39   31.85     5.63   32.95     5.06   33.87
  47k          330   9.08   31.21     7.49   32.88     6.43   34.21     5.66   35.31     5.09   36.24
  56k          375   9.11   32.29     7.51   33.96     6.44   35.30     5.67   36.40     5.10   37.34
  62k          400   9.12   32.84     7.52   34.51     6.45   35.85     5.68   36.95     5.10   37.89
  68k          435   9.14   33.55     7.53   35.23     6.46   36.57     5.69   37.67     5.11   38.61
  75k          468   9.15   34.18     7.54   35.85     6.46   37.19     5.69   38.30     5.11   39.24
   
   
  Hope you find this useful.


----------



## runeight

jdk, how do your SQ listening tests correlate to the tables?


----------



## jdkJake

They actually correlate pretty well. The amount of NFB seemed to track for the values I listened too (I listened to a bunch, but not all on the chart by any means). It certainly came in handy to to try and re-establish a NFB reference point as I reduced CL gain. 
   
My main goal was to do just that; reduce CL gain to make the amp more suited for my sources and the volume level at which I usually listen. I was initially not that interested in changing the NFB. Of course when I made my initial jump and went from a 1.3k at R11 to a 2.4k, I was not prepared for the difference in sound quality that the extra ~5db of NFB would make. So, I was really caught off guard by that. Turns out a change as small as 2db can make a noticeable difference with even 1db being discernible at times (more of a finesse change). 
   
So, my suggestion to those who wish to try the various settings is to pick your CL gain first, match the OL as close as possible to the NFB you are used to having and then varying the OL (NFB) from that point. It is pretty amazing how you can change the response characteristic of the amp by varying the NFB. I did not understand what I was hearing at first, but, I now understand the response in the midrange flattens and extends the bandwidth out to bring out more of the upper treble and low bass.
   
Turns out, for my headphones (HD650 and HF-2) a little extra NFB is not a bad thing. Both of those phones have a bit of a mid-bass emphasis that the extra NFB takes down  while bringing forward more high end detail. IMO, you can go a bit too far and the top end tends to develop what I might call a ‘sheen’ for lack of a better word. But, it is easy to back off. I find this starts to happen at around ~39db. The funny part is, for some music, say acoustic guitar, it might be preferable. But for all around use, it is too much for me. 
   
In any case, the beauty is that you can set it to where you like it and have it fit your phones (and musical taste) perfectly. I guarantee you, if you think the HD650 has a veil, 40db of NFB on this amp will erase that thought for sure!
   
Good stuff.


----------



## BK_856er

I finally got things off the ground.  I'm relatively new to DIY, so I turned the careful dial up to 11 and took my time...two full days to get the boards built up.  So far, so good!
   
  BK


----------



## stringgz301

Well done!  How about some shots of the bottom of the boards and an overhead shot of the back power supply sections.Some extra sets of eyes to check the work before power-up is always a good thing.


----------



## jdkJake

Nice work!

 Stringgz is right, a couple shots from the back and bottom would be great if you are concerned and want an extra pair of eyes.

From the top shots, you workmanship looks excellent.


----------



## BK_856er

Thanks, guys!  I hope that what I lack in skills I can make up for with extra care.
   
  Just finished de-fluxing the boards with IPA.
   
  Below are some shots of the PS section and the uderside.  The black boards were a bear to work with in terms of seeing the work and getting the right lighting.  Difficult to photograph, too.
   
  Do the expert eyes have any comments or see any issues?
   
  BK


----------



## sachu

By and large..looks excellent!!


----------



## jdkJake

I agree with Sachu, it looks good. You certainly did a heck of a job cleaning it up. You could eat off that thing! 
   
  A couple suggestions, I would trim the rectifiers for the heater PS closer to the board. Those tails still are pretty long and might be a shorting hazard if you leave them like that. Also, if you really mean to solder the heatsinks, then you need to apply a LOT more heat and a LOT more solder. For all intents and purposes, they are mostly floating (which is fine electrically and most likely structurally as well).
   
  I see the sumr waiting in the background. Wire it up and fire those bad boys up already!


----------



## johnwmclean

Nice job on those boards, very clean!


----------



## BK_856er

Quote: 





jdkjake said:


> I agree with Sachu, it looks good. You certainly did a heck of a job cleaning it up. You could eat off that thing!
> 
> A couple suggestions, I would trim the rectifiers for the heater PS closer to the board. Those tails still are pretty long and might be a shorting hazard if you leave them like that. Also, if you really mean to solder the heatsinks, then you need to apply a LOT more heat and a LOT more solder. For all intents and purposes, they are mostly floating (which is fine electrically and most likely structurally as well).
> 
> I see the sumr waiting in the background. Wire it up and fire those bad boys up already!


 

 10-4 on those items you mention - thanks.
   
  I still need to build up several more components for the amp (see below) and obtain a 12x12x3 case, but I'll try to get som electrons flowing through the SumR soon.  First class all the way!
   
  Just installed a twin 4' fluorescent light directly above my workspace to bathe the area in photons - sucks to be over 40.
   
  BK


----------



## stringgz301

Reporting back on a recent tube purchase for the EHHA: 6N27P.  I was curious about these having seen them on eBay as an equivalent to 6GM8's.  Supposedly the good ones come from the Reflektor factory and date from the early 70's.  I originally purchased a pair and after waiting for a month for them to show up one of them turned out to be "bad" (the DC offset wouldn't settle - just seemed to oscillate randomly).  After wasting time debating with that seller on whether it was the tube or my gear I buought another pair from another seller (uralspirit - $28 + shipping for the pair).  This second pair have 1974 date codes and appear unused.
   
  After installing them in the EHHA and firing it up the DC offset settled very quickly on both channels and the bias dropped nicely as they warmed up.  After about 30 minutes I started listening and wasn't very excited about what I heard (compared to the Telefunken 6GM8's that I'd been using): sound very tilted towards the top end and somewhat thin overall.  So stopped listening and left the amp on overnight.  Actually left it on for about 24 hours before I listened again.  Wow, what a difference.  These tubes are the detail kings.  The soundstage was much bigger than the Tele's, and instruments were clearly separated.  Voices were really pleasing and smooth.  Bass was clear and punchy and went just as deep as the Tele's.  If you think tubes in general are soft and mushy, these russian guys in the EHHA will open your eyes: crisp, clean, punchy, yet very musical.  Solid-state with a touch of tube sparkle and warmth.
   
  How do these compare to the Tele's?  The latter (through my HF2's) sound like you're sitting onstage right in front of the band.  Being so close, many of the instruments often sound 3-dimensional, especially drums, cymbals, and acoustic guitars, and all instruments have a rich, organic tone.  However, being so close there is often significant overlap/layering of the instruments which isn't unpleasant but just a fact.  The 6N27P are like being a few rows back (but still pretty close with the HF2's).  All the instruments are clearly defined and easily identifiable and sound natural.  The trade off seems to be 3-dimensionality vs. soundstage.  I haven't decided which I prefer.  It may depend on musical choices, with the Tele's for small ensemble jazz and bluegrass and the Russians for rock and larger ensembles.  In both cases, the EHHA provides incredible transparency and firmness, allowing you to see deep into the sound and providing an even sound from the very deep to the very high.
   
  I love having tough choices like this!


----------



## jdkJake

Great write-up stringgz! Nice way of describing the differences.
   
  I have yet to roll tubes through my box but now you got me thinking since I am finally done with my CL/OL/NFB experiments. I have some dutch westinghouse I should really try out, although their construction looks close if not identical to the amperex I have in there currently.
   
  I think cobaltmute also has a set of those 6N27P tubes as well.


----------



## stringgz301

I was told that back in the day there were only 2 factories producing 6GM8's: 1 Amperex and 1 Telefunken.  Supposedly all others are just relabeled version of one or the other.  Curious to hear what other's experience is.


----------



## jdkJake

That is interesting. I seem to have three basic types:
   
  The Amperex set I am currently running as well as the Westinghouse sets all look alike in construction. All marked "Made in Holland" with a very high halo and a mostly unseen getter ring:
   

   
  I also have another set branded Zenith and marked "Made in Holland" with a radically different halo/getter design with a low, less round halo and a high, easy to see getter ring:
   

   
  I also have a one-off tube branded Zenith and marked "Made in Germany" with yet another halo design with a smooth round ring and unseen getter (obscured by the getter flash):
   

   
  Any of these look familiar?


----------



## sachu

hmm...guess i need to buy a coupleof 6N27s..i do love the teles the best thus far followed by the amperex..the valvos are nice as well..have a thicker midrange but lose detail levels.


----------



## stringgz301

I have 3 versions:
   
  Telefunken and Siemens
   

   
  Reflektor
   

   
  The Siemens and the Tele look very similar in construction but sound completely different.  The Siemens is marked as made in Germany but has a Heerlan factory code on it.


----------



## jdkJake

That makes sense as your siemens look much like the second set I posted pics of, which, are made in holland as well. Looks like I need another tele to make a set. I will see if I can pick one up.

Thanks for posting the pics, it really helps a lot to see the various constructions.

If you are up for it, let me know and I will send you a set of the westinghouse/amperex A-frames to try out as well.


----------



## stringgz301

Quote: 





sachu said:


> hmm...guess i need to buy a coupleof 6N27s..i do love the teles the best thus far followed by the amperex..the valvos are nice as well..have a thicker midrange but lose detail levels.


 


  If I had to guess I'd say that your Valvo's are the same as the Holland-made Siemens above, because that's exactly how I'd describe their sound.


----------



## BK_856er

Success!  I powered up my boards today and everything went exactly according to the setup instructions.  What a relief.
   
  With my 114.83VAC line, the SumR was puting out 7.1V and 32.3V during initial setup.  The Rails Supply measurements were ~30.2VDC.
   
  How stable should the Mosfet bias voltage be?  Even after some warmup I had to bump it up 10-20mV a few times to maintain 220mV.  Normal?
   
  I'm so happy things are on track for my first real build!!  
	

	
	
		
		

		
			




   
  BK


----------



## johnwmclean

Quote: 





bk_856er said:


> How stable should the Mosfet bias voltage be?  Even after some warmup I had to bump it up 10-20mV a few times to maintain 220mV.  Normal?


 

 Congrats mate, top effort. I usually leave a new amp on for an 1 – 1 1/2 hours or so, with no music playing, then bias. Then just leave it, the bias will go up and down, usually higher when there’s no music, lower (more efficient) when playing music for longer periods. 
   
  So yeah, perfectly normal!


----------



## jdkJake

Excellent news BK. Your methodical approach appears to have really paid off.

As John already stated, the bias will vary over time and will actually go down as the parts get warmer. MOSFET's have a negative thermal response. Once you case it up, you can run them for a few hours and then set them one final time and then forget about them.

Man, you have some low VAC where you live. Did you measure the voltage at the regulators? Where did you measure 32.3V? If you get a chance, let it warm up an hour or so, check the bias and then measure the input to the regulators. It would be interesting to see the contrast as most of the other builders have VAC closer to 120VAC.


----------



## BK_856er

Quote: 





jdkjake said:


> Excellent news BK. Your methodical approach appears to have really paid off.
> 
> As John already stated, the bias will vary over time and will actually go down as the parts get warmer. MOSFET's have a negative thermal response. Once you case it up, you can run them for a few hours and then set them one final time and then forget about them.
> 
> Man, you have some low VAC where you live. Did you measure the voltage at the regulators? Where did you measure 32.3V? If you get a chance, let it warm up an hour or so, check the bias and then measure the input to the regulators. It would be interesting to see the contrast as most of the other builders have VAC closer to 120VAC.


 

 Thanks for the info on the temp/bias voltage, guys.  Feels really satisfying to finally have this thing alive and without drama.
   
  No, I didn't measure at the regulators - just followed the basic setup instructions.  Reading up much further it looks like I can measure across the +/- pads of C1R to get that value, or at the regulator pins directly (which points specifically?).
   
  The 32.3V came from the SumR secondaries.  I've been regularly monitoring my line voltage with a very good DMM since the topic came up here, and sure enough my 115V is quite stable.
   
  I'd be happy to take other measurements if they'd be informative for others, but I may need some help in identifying the proper test points/conditions.
   
  BK


----------



## jdkJake

Once it has powered up and stabilized, you want to measure the input pins of the LM317 and LM337. Be sure it has stabilized and is at the correct bias voltage. It pulls quite a bit of power until things stabilize.

For the LM317, pin 3 is the input (rightmost facing front). For the LM337, pin 2 is the input (middle pin). Careful, it is crowded by those pins and you do not want to accidentally short anything.

Thanks for doing this, it will provide good data against the data taken at 120VAC.


----------



## BK_856er

Quote: 





jdkjake said:


> Once it has powered up and stabilized, you want to measure the input pins of the LM317 and LM337. Be sure it has stabilized and is at the correct bias voltage. It pulls quite a bit of power until things stabilize.
> 
> For the LM317, pin 3 is the input (rightmost facing front). For the LM337, pin 2 is the input (middle pin). Careful, it is crowded by those pins and you do not want to accidentally short anything.
> 
> Thanks for doing this, it will provide good data against the data taken at 120VAC.


 

 Here you go:
   
  114.41VAC line voltage, ~30min warmup, 223mV bias (not adjusted from previous day).  DC offset 0.0000V +/- 0.0003V on both boards (yeah!).
   
  SumR measures 6.9V and 29.6V at the board inputs and heater output is 6.299V for both boards (not adjusted from previous day).
   
  Board #1 regulators:  VR- = 36.10V, VR+ = 36.24V, TP3 = 7.92V.
   
  Board #2 regulators:  VR- = 36.30V, VR+ = 36.38V, TP3 = 7.96V.
   
  Rail voltages are 29.9V/30.1V.
   
  The LM317 and LM337 parts are Fairchild (not the ON Semi on the BOM).
   
  Does that cover all the bases?
   
  BK


----------



## jdkJake

Yes it does, thank you very much. Those numbers look good. Very good.

Think you might be able to get a bit more accuracy on the DC offset out of the servo? 

Time to get some tunes going through it and let us know what you think of the sound.

BTW: I am using the fairchild parts as well. I have had no issues with them at all.


----------



## peppe

Jeff @ Glass Jar Audio has a kit up for the Rev A of this amp.  I don't know how he does it.  Its like $20 cheaper than the project i have at mouser based off the latest bom.
   
  Not sure i can buy and build this before a planned move next year, but thank you Jeff.  Probably should wait until after the move so the wife doesn't get upset


----------



## BloodInside

I test-wired my BJT build today and I get a very-close to zero DC-offset (< 1mv) and was able to set the bias. The experience was not entirely smooth due to two faulty components (one LM317 and one LT1085). After replacing them today the power supplies both worked properly and the rest of the amplifier worked without any trouble.
   
  I still have to hook up the two E12 boards and attach some headphones, but I'm already very happy!
   
  Some pics (sorry for the bad lighting):


----------



## BoilermakerFan

Did you buy the case or build it yourself?  If you built it, great job on the keyed miter corners! 
   
  Which BJTs are you running?  The coveted Toshiba 968s?


----------



## BloodInside

I bought the case from a small DIY-audio company. It made out of oak wood and the corners are indeed very nice.
   
  I'm using the BJT specified by the BOM (the MJE243 and MJE253).


----------



## holland

Quote: 





bloodinside said:


> I bought the case from a small DIY-audio company. It made out of oak wood and the corners are indeed very nice.


 


  Link/name of said company?


----------



## BloodInside

Quote: 





holland said:


> Quote:
> 
> 
> 
> ...


 

 Automatic Electric Europe. Unfortunately their website is in Dutch: http://www.ae-europe.nl/aanbieding_behuizingen.htm. They're also in the progress of building a new website/shop, which is also available in English: http://www.transformatorspecialist.nl/index.php?cPath=22_30_44. Not sure if they ship outside of the Netherlands (but perhaps you live there given your name...).


----------



## stixx

Quote: 





> Automatic Electric Europe. Unfortunately their website is in Dutch: http://www.ae-europe.nl/aanbieding_behuizingen.htm. They're also in the progress of building a new website/shop, which is also available in English: http://www.transformatorspecialist.nl/index.php?cPath=22_30_44. Not sure if they ship outside of the Netherlands


 
  Sure they will ship outside of the Netherlands... at least to Germany 
	

	
	
		
		

		
			





.
  Good company, very recommended...


----------



## jdkJake

Nice build Bloodinside! As the other have mentioned, that case is really nice. A very contemporary look.

Do you get any hum with the one board being so close to the transformers?

Another question, how are you going to control the volume?


----------



## jdkJake

BTW, not sure what the European electrical standards are, but, you might want to consider wiring safety ground to the chassis and then the chassis to star ground via a ground loop breaker. It would be electrically safer and less chance of inducing ground loops.

Just a thought....


----------



## BloodInside

Quote: 





jdkjake said:


> Nice build Bloodinside! As the other have mentioned, that case is really nice. A very contemporary look.
> 
> Do you get any hum with the one board being so close to the transformers?
> 
> Another question, how are you going to control the volume?


 


  I haven't gotten to connecting my headphones yet. I planning to do that tomorrow or during the weekend. I didn't really think about the hum it might give by placing the boards that closing to the transformers. I hope I don't get any hum, but I still have some room to move stuff around. Perhaps snap of the power supply sections and placing them next to the transformer.
   
  The small on the left of the case is a metal axle support. The axel will be connected to the volume pot so I can control the volume.
   
  Quote: 





jdkjake said:


> BTW, not sure what the European electrical standards are, but, you might want to consider wiring safety ground to the chassis and then the chassis to star ground via a ground loop breaker. It would be electrically safer and less chance of inducing ground loops.
> 
> Just a thought....


 

 I will look into that. Thanks!


----------



## Ferrari

> Quote:
> 
> 
> 
> ...


 

  
  [size=x-small]*BloodInside*, using the 2-pole AC plug (Class II Euro-plug), as common in our Dutch living room, there is no need to worry about the AC ground (similar to other hifi-equipments in your room… just skip it !!!). [/size]
   
  [size=x-small]Appliances in your kitchen or bathroom areas are another story, *they do require safety earth*.[/size]


----------



## BloodInside

Quote: 





ferrari said:


> > Quote:
> >
> >
> >
> ...


 
   
  Indeed, other hifi equipment is also using the 2-pole plug, never thought about that. That makes it a bit less complicated, thank you!
   
   
  Today I made an attempt to test one of my E12 boards, but managed to screw it up by shorting pin 6 and 7 on the OPA551 while measuring. It seems to have damaged the D1 zener diode, because I now get around 52Volt DC on the VCC pin of the chips. The OPA551 seems to have survived, because the relay still triggers after 3 seconds, but the TL081 has probably died because of the 52Volt. Taking a break now, before I screw up something else and just gonna order some replacement parts...


----------



## jdkJake

bloodinside said:


> Today I made an attempt to test one of my E12 boards, but managed to screw it up by shorting pin 6 and 7 on the OPA551 while measuring. It seems to have damaged the D1 zener diode, because I now get around 52Volt DC on the VCC pin of the chips. The OPA551 seems to have survived, because the relay still triggers after 3 seconds, but the TL081 has probably died because of the 52Volt. Taking a break now, before I screw up something else and just gonna order some replacement parts...





 


Don't feel bad, I did the same thing with one of my e12's. Ended up taking out Q1 and/or Q2. I did not isolate which one, I just replaced both.

If you are using the v1.2 e12, you can also take the measurement at the base of R10, directly above pin 8 of U2. It is not quite as tight right there.


----------



## runeight

So, BloodInside, are you listening yet?


----------



## BK_856er

Just built up the new version (v2.01) of the AMB e12 muting/delay circuit.  Case and Greenlee punch on the way - getting closer...
   
  BK


----------



## ujamerstand

Heh, I've got the protoboards here that I need to start building for my ehha as well... How much did it cost you to populate both boards?


----------



## Sathimas

I'd also like to build an EHHA rev. A this year (end of summer)
   
  Would it be possible to install smaller heatsinks?
  I'd like to set the boards in a case of only 5cm height - with very good ventilation (open top).


----------



## lozanoa11

If I buy the kit (http://www.glassjaraudio.com/product.sc?productId=29&categoryId=6) will I need anything else besides a case for it? I have built a cmoy before, will this be way over my head?


----------



## Lil' Knight

The kit is pretty much completed so you need the case, all kinds of connectors and internal wiring.


----------



## stixx

Quote: 





> Would it be possible to install smaller heatsinks?
> I'd like to set the boards in a case of only 5cm height - with very good ventilation (open top).


 
  When you scroll through the last pages of the 'post pics of your builds' thread you will find the EHHA by John W McLean... only 5cm high with heatsinks cut to depth... you probably saw that one already 
	

	
	
		
		

		
			





.


----------



## jdkJake

stixx said:


> When you scroll through the last pages of the 'post pics of your builds' thread you will find the EHHA by John W McLean... only 5cm high with heatsinks cut to depth... you probably saw that one already
> 
> 
> 
> ...





 


IMHO, that is not a fair comparison. John's build uses a different, external power supply and side mounts the mosfets on a heat sink that runs the length of the chassis. His implementation is night and day different from a standard rev A build.

Based upon the readings I have taken on heat, I would not advise going any smaller on any of the heat sinks.


----------



## jdkJake

lozanoa11 said:


> If I buy the kit (http://www.glassjaraudio.com/product.sc?productId=29&categoryId=6) will I need anything else besides a case for it? I have built a cmoy before, will this be way over my head?





 


Hard to say. How did the cmoy go? How do you feel about you solder skills? Have you done a PCB-based build before? Are you comfortable with a multimeter? You will be working with AC power, so, safety becomes something you need to respect. Debugging problems is another aspect to consider as well.

The build is relatively straight-forward if you take your time. The part count is fairly high and board density is tight, but, not overly so. As Lil'Knight points out, the wiring and casework is a large part of this build, perhaps even more time consuming than stuffing the boards. Ready and willing to take on the casework?


----------



## Alcaudon

Has anyone built (or is building or even thinking to build) a balanced Rev. A. EHHA? I'm trying to decide whether to go balanced or nor (it would be my first balanced build).
   
  Also, regarding heatsinking..... I would also like to go low profile and I'm thinking to go the same way as johnwmclean did with his EHHA I, but I'm a bit concerned about mounting the transistors on the sides and wire them to the boards, what do you think?
   
  Thanks!!!


----------



## jdkJake

IMO, the layout of the output devices on the original EHHA board is more conducive to the type of heatsink placement like John did with his build.


----------



## Alcaudon

Quote: 





jdkjake said:


> IMO, the layout of the output devices on the original EHHA board is more conducive to the type of heatsink placement like John did with his build.


 

 Yes, I know, but I thought that maybe splitting the power supplies from the amp board you could place the four boards (in case of going balanced) close to the sides, mount the transistors on the heatsinks and wire them to the boards.


----------



## BK_856er

Quote: 





ujamerstand said:


> Heh, I've got the protoboards here that I need to start building for my ehha as well... How much did it cost you to populate both boards?


 


 For the v2 e12 units?  Only $23.46 shipped to populated two boards (excluding boards).
   
  BK


----------



## holland

Quote: 





alcaudon said:


> Yes, I know, but I thought that maybe splitting the power supplies from the amp board you could place the four boards (in case of going balanced) close to the sides, mount the transistors on the heatsinks and wire them to the boards.


 


  I was going to go with big heatsinks for my EHHA I build.  I was planning on side mounting the entire board, power amp style.  I don't think the tubes will fall out.  This applies to the rev A as well.  All you need is space and a tall case, but I'm pretty sure it'll work fine on a 3U case.  Side mount and run the PSUs up the middle of the chassis, for balanced.  Xformers in a separate box and run AC in or convert to DC and run the DC, DC regulation near the amp.


----------



## Alcaudon

Quote: 





holland said:


> I was going to go with big heatsinks for my EHHA I build.  I was planning on side mounting the entire board, power amp style.  I don't think the tubes will fall out.  This applies to the rev A as well.  All you need is space and a tall case, but I'm pretty sure it'll work fine on a 3U case.  Side mount and run the PSUs up the middle of the chassis, for balanced.  Xformers in a separate box and run AC in or convert to DC and run the DC, DC regulation near the amp.


 

 Yes, it could be done, but I'm looking for a low profile case with the tubes sticking out from the top, and this way you'll need a very tall case.


----------



## jdkJake

alcaudon said:


> Yes, I know, but I thought that maybe splitting the power supplies from the amp board you could place the four boards (in case of going balanced) close to the sides, mount the transistors on the heatsinks and wire them to the boards.





 


Are you going to use MOSFETs or BJTs?

Most of what I have read in various forums indicates "air wiring" MOSFETs is not necessarily a good idea. I am not sure about BJTs.


----------



## jdkJake

bk_856er said:


> Just built up the new version (v2.01) of the AMB e12 muting/delay circuit.  Case and Greenlee punch on the way - getting closer...
> 
> 
> 
> ...





 


Those look nice BK. The new versions look to be far simpler and certainly less expensive to build. I am really glad to see Ti fixed the mounting hole locations. They should be far easier to work with as well.

Do you still need to heatsink the transistors? Or is that now optional?


----------



## Alcaudon

Quote: 





jdkjake said:


> Are you going to use MOSFETs or BJTs?Most of what I have read in various forums indicates "air wiring" MOSFETs is not necessarily a good idea. I am not sure about BJTs.


 
   
  Mosfets. Yes, I've read the same, this is what holds me back. Guess that I'll have to stick to a "conventional" building and forget about low profile and tubes sticking out


----------



## jdkJake

alcaudon said:


> Mosfets. Yes, I've read the same, this is what holds me back. Guess that I'll have to stick to a "conventional" building and forget about low profile and tubes sticking out





 


You could always bottom mount them from the underside of the board and use a bottom mounted heatsink. I have seen that done before. Not sure how well it conducts heat, but, it is an option.


----------



## Alcaudon

Quote:  





>





> You could always bottom mount them from the underside of the board and use a bottom mounted heatsink. I have seen that done before. Not sure how well it conducts heat, but, it is an option.


 

 Yes, is another option, but I'm a bit concerned about heat accumultaing on the board due to air convection. Also, it won't reduce the height of the case.


----------



## Sathimas

wouldn't it be possible to reduce the bias-current for less heat dissipation?
   
  I mean 100mA is way enough - I have a JISBOS buffer here biased to 20mA and this
  is more than enough to make my DT880 sing  I hear no difference to my M³.


----------



## dBel84

FWIW my original EHHA had airwired mosfets and beefy off board heatsinks. I have close-ups somewhere but this will give you an idea. 
   

   
  The front and rear plates were 10mm copper, the entire thing got to about 40 odd celsius, but that was crazy biasing ..dB


----------



## jdkJake

alcaudon said:


> Yes, is another option, but I'm a bit concerned about heat accumultaing on the board due to air convection. Also, it won't reduce the height of the case.





 


No, I meant to take a page from the playbook of a master:

http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/3225#post_4153931

(see Ferrari's kumisa III build on this page)


----------



## BK_856er

Quote: 





jdkjake said:


> Those look nice BK. The new versions look to be far simpler and certainly less expensive to build. I am really glad to see Ti fixed the mounting hole locations. They should be far easier to work with as well.Do you still need to heatsink the transistors? Or is that now optional?


 


 My understanding is that the transistor heatsinks are no longer required, but that conclusion is only based on the fact that Ti does not mention them on his v2 pages.  I should probably get confirmation on that detail.
   
  In addition to the changes in the circuit, there is a hefty ground layer covering most of both sides.  Definitely took more heat to solder!
   
  BK


----------



## jdkJake

dbel84 said:


> FWIW my original EHHA had airwired mosfets and beefy off board heatsinks. I have close-ups somewhere but this will give you an idea.
> 
> 
> 
> ...





 


Wow, that is crazy small. Very nice.

What gauge wire did you use to airwire the MOSFETs? Did you make any attempt to match the lengths (either in physical length or electrical characteristic)?


----------



## dBel84

I kept the lengths the same but nothing else was considered. iirc the gauge was 20 ..dB


----------



## holland

I would keep the gate resistors on the pin.  Other than that you should be ok.


----------



## jdkJake

Quote: 





holland said:


> I would keep the gate resistors on the pin.  Other than that you should be ok.


 

 Interesting. Why is that? To keep the signal level higher until it actually reaches the gate? Is this for better noise rejection?


----------



## holland

Quote: 





jdkjake said:


> Interesting. Why is that? To keep the signal level higher until it actually reaches the gate? Is this for better noise rejection?


 


  It's to help minimize/suppress oscillation at the gate.  MOSFETs have both parasitic capacitance and inductance that work together to form a tank/reservoir that can be excited into oscillation.  The R in series is to slow the rise of the gate voltage (RC filter, with C from the gate capacitance), and hence slow the switching speed of the MOSFET.
   
  In short, stick it on the pin, as close as possible.  The EHHA layout has this, so don't lose it.


----------



## jdkJake

Quote: 





holland said:


> It's to help minimize/suppress oscillation at the gate.  MOSFETs have both parasitic capacitance and inductance that work together to form a tank/reservoir that can be excited into oscillation.  The R in series is to slow the rise of the gate voltage (RC filter, with C from the gate capacitance), and hence slow the switching speed of the MOSFET.
> 
> In short, stick it on the pin, as close as possible.  The EHHA layout has this, so don't lose it.


 

 Thank you! 
   
  I learned something tonight. Makes it a good night indeed!


----------



## BK_856er

Officially, another one lives!
   
  Took me a couple tries to get the grounding right, but it's playing music and it sounds mighty fine.  
	

	
	
		
		

		
		
	


	



   
  Critical listening will come later with a proper setup, but I can already tell that this amp has some very nice qualities and the two of us are going to get along just fine.
   
  BK


----------



## BloodInside

Quote: 





runeight said:


> So, BloodInside, are you listening yet?


 

 No, unfortunately not. I didn't get any chance to work on it during the weekend. I should receive my E12 replacement parts this week, so I'm probably going to start working on that first. Based on 

[*] jdkJake concerns I also decided to snap of the power supply sections from the amplifier so I can move the amplifier away from the transformers.  

[*]   

[*] I'm quite excited to start listening. My Little Dot MK IV is a bit underpowered for driving the Hifiman HE5-LE (but still sounding great), so I'm curious what the EHHA will do...


----------



## qusp

some of the builds are looking really great guys!! my interest is still piqued, its between this and a borbely/CATO tube/mosfet hybrid. I do like how I have a couple spare S22's that could be used for a balanced build, i'm waiting to hear Johns balanced build at the next meet. anyone thought about perhaps subbing in semisouth power jfets for the mosfets? I have some extras lying around (R550/R100) after buying some for an F5X build and deciding to at least initially use japanese toshiba mosfets (2SK1530/J201) instead


----------



## jdkJake

bk_856er said:


> Officially, another one lives!




 


Great news BK!

What is the device next to the TKD pot?


----------



## jdkJake

bloodinside said:


> No, unfortunately not. I didn't get any chance to work on it during the weekend. I should receive my E12 replacement parts this week, so I'm probably going to start working on that first. Based on jdkJake concerns I also decided to snap of the power supply sections from the amplifier so I can move the amplifier away from the transformers.





 
 


So, I was not so much concerned as much as I was interested to see if you had any issues. I kind of wished you had listened to it prior to making any changes to your layout. It may have been just fine the way it was in your original layout. I am sorry if I gave the wrong impression. That was certainly not my intent.


----------



## ujamerstand

Quote: 





qusp said:


> some of the builds are looking really great guys!! my interest is still piqued, its between this and a borbely/CATO tube/mosfet hybrid. I do like how I have a couple spare S22's that could be used for a balanced build, i'm waiting to hear Johns balanced build at the next meet. anyone thought about perhaps subbing in semisouth power jfets for the mosfets? I have some extras lying around (R550/R100) after buying some for an F5X build and deciding to at least initially use japanese toshiba mosfets (2SK1530/J201) instead


 

 Semisouth have both n-channel and p-channel power jfets?


----------



## BloodInside

Quote: 





jdkjake said:


> So, I was not so much concerned as much as I was interested to see if you had any issues. I kind of wished you had listened to it prior to making any changes to your layout. It may have been just fine the way it was in your original layout. I am sorry if I gave the wrong impression. That was certainly not my intent.


 

 No problem, I'm glad you guys are giving me feedback and advice. And yeah, I probably should have listened before I decided. Your comment started me thinking and I wanted to move the boards around as a precaution.
   
  And it will turn out for the better. I wasn't to happy about the work I did on drilling the holes for mounting the boards, so I can do that better now (with everything I've learned from doing it wrong). And I even think the wiring will turn out to be cleaner than previously.


----------



## BK_856er

Quote: 





jdkjake said:


> Great news BK!What is the device next to the TKD pot?


 


 AMB e24/s24 for lighted Bulgin power switch + thermal protect.
   
  BK


----------



## Alcaudon

Quote:  





> No, I meant to take a page from the playbook of a master:http://www.head-fi.org/forum/thread/85561/post-pics-of-your-builds/3225#post_4153931(see Ferrari's kumisa III build on this page)


 

 Oh! now I see what you mean 
	

	
	
		
		

		
			




   
  Yes, this could be a solution, I'll definitely have to check that, thanks jdJake 
	

	
	
		
		

		
		
	


	



   
  Still wondering if someone has any experience with a balanced EHHA Rev. A....


----------



## BoilermakerFan

Quote: 





alcaudon said:


> Quote:
> 
> 
> 
> ...


 

 Balancing the EHHA would result in twice the gain and that is probably way too much unless you have a very low output source or you really increase the NFB and drop the CL gain.  I don't think I would want to make those two changes since they will have large effects on the SQ.  The EHHA could be modded and biased to output more power with bigger heatsinks even in SE, so I don't see the need for the balanced amp with headphones.  I was considering a balanced or bridged build for speakers, but now I think just paralleling output FETs and mounting them off board makes more sense; however, even this will require tweaks to the PS and several resistors need to be changed too so I'm reconsidering even those changes.


----------



## BebopMcJiggy

I think the NFB and OL gain are tied together so raising one while lowering the other is accomplished how?  At least the original EHHA worked this way.  He could lower the closed loop gain though?


----------



## holland

OL and NFB are tied together in that the OL gain defines how much NFB is used to achieve the CL gain.  The CL gain, being somewhat fixed.  Think opamp.


----------



## BebopMcJiggy

Yes but again I don't see how this helps build a balanced amp at all, while changing the CL gain would :O


----------



## holland

LOL.  My response was to clarify the apparent misunderstanding/misrepresentation of OL gain, NFB, and CL gain.  Again, think opamp, because it is.  For the record, I think BMF meant CL gain, and it was a simple error in typing one thing but meaning another.


----------



## BoilermakerFan

Quote: 





holland said:


> LOL.  My response was to clarify the apparent misunderstanding/misrepresentation of OL gain, NFB, and CL gain.  Again, think opamp, because it is.  For the record, I think BMF meant CL gain, and it was a simple error in typing one thing but meaning another.


 
   
  Yes, I was going to go back and edit it...
   

  
   


  Quote: 





bebopmcjiggy said:


> Yes but again I don't see how this helps build a balanced amp at all, while changing the CL gain would :O


 

 http://www.cavalliaudio.com/ehha/images/EHHABoardWiringFourChannel.gif
   
  No reason you can't build it balanced, but you will have a lot of gain, twice the standard EHHA.  The point we were trying to make is that there is limited amount of adjustment that can be made without seriously jeopardizing the sound quality.  If you have low level output sources you'll be fine, otherwise you may clip the signal with a balanced amp and balanced source.  There are other ways to knock the signal down more via a higher resistance in a shunted attenuator, etc.  A transformer PVC is another way to take at least 6dB of signal level out too and it's secondary advantage is that it will deliver a balanced signal to the amp even with a SE source.


----------



## BloodInside

I finished rearranging the boards. From down to up you see the transformers, the heater and power supply boards, the amplifiers, the E12 boards and the Alps potentiometer.
    

   
  The EHHA boards are already mounted on the bottom plate, but I have still to mount the E12's and the perfboard boards. Also have to fasten the binders, probably going to use ty-wraps for that. 
   
  The binders are going to guide the wires running from and to the boards so that everything looks clean. The bottom perfboard (between the power supplies) is a hub for the star connections and the top perfboard is to decouple the pot (screwed to the bottom plate) from the case. That way I can remove the case from the bottom plate without needing to desolder connections.
   
   
  I'm going to have two headphone outputs, one regular 6,3mm jack and a XLR 4-pin for my Hifiman HE5-LE (so I can ditch the adapter cable). The outputs are going to be on the side of the amplifier (which in the top of the photo) where the big gap is. They are going to be mounted on a aluminum plate which will fit into the gap.


----------



## ujamerstand

Nicely done. Did you make the chassis yourself?


----------



## jdkJake

That looks great Bloodinside! Excellent use of available space!

The binders are an interesting idea for cable management.


----------



## BoilermakerFan

Quote: 





jdkjake said:


> That looks great Bloodinside! Excellent use of available space!
> 
> The binders are an interesting idea for cable management.


 

 I agree!  That has given me the idea to acquire some SS or copper tubing and use an abrasive blade to kerf out about 2/3 of one half so it would look similar to the binder, but be solid metal.  Soft copper tubing could be bent to shape first too.


----------



## BloodInside

Quote: 





ujamerstand said:


> Nicely done. Did you make the chassis yourself?


 

 Thanks. I bought the chassis/case from a Dutch company called Automatic Electronics Europe. They have a Dutch website and they are in the progress of building a new webshop which is also available in English.
  
  Quote: 





jdkjake said:


> That looks great Bloodinside! Excellent use of available space!
> 
> The binders are an interesting idea for cable management.


 

 Thanks. I picked up that idea from the modeltrain hobby scene. It is cheap (paid about 8 euro's for a 100 A4 binders) and works really well.


----------



## Alcaudon

Thanks BoilermakerFan and holland for the advices, and explanations.
   
  The idea was to drive a pair of k1000 with a balanced ehha, but maybe the ehha is not a good chice for a first balanced amp, too many complications. I think I'm staying with a standard build and save money/effort for a balanced Bijou in the future 
	

	
	
		
		

		
			




  
  Quote: 





boilermakerfan said:


> Quote:
> 
> 
> 
> ...


 
   
  Quote: 





holland said:


> OL and NFB are tied together in that the OL gain defines how much NFB is used to achieve the CL gain.  The CL gain, being somewhat fixed.  Think opamp.


----------



## jdkJake

alcaudon said:


> The idea was to drive a pair of k1000 with a balanced ehha, but maybe the ehha is not a good chice for a first balanced amp, too many complications. I think I'm staying with a standard build and save money/effort for a balanced Bijou in the future



 


If gain is your concern with a balanced EHHA, you could always run 2.4k at R11 and somewhere around 33k at R13 and R14 and come in around a gain of ~10. This is just slightly above the default single-ended gain of ~9 with very close to the same amount of NFB (~34db).

That being said, I was always under the impression the k1000's appreciate a bit of extra gain, so, perhaps it is a non-issue with those specific phones. I do not own a pair, so, I cannot comment on their performance.

Just a thought before you dismiss the idea entirely.


----------



## holland

Quote: 





jdkjake said:


> If gain is your concern with a balanced EHHA, you could always run 2.4k at R11 and somewhere around 33k at R13 and R14 and come in around a gain of ~10. This is just slightly above the default single-ended gain of ~9 with very close to the same amount of NFB (~34db).That being said, I was always under the impression the k1000's appreciate a bit of extra gain, so, perhaps it is a non-issue with those specific phones. I do not own a pair, so, I cannot comment on their performance.Just a thought before you dismiss the idea entirely.


 


  Agreed.  It's also no more complicated than any other amp or fast bipolar opamps to begin with, which I why I keep bringing up the opamp reference.  The EHHA I was unity gain stable, you just need compensation caps.  Mine is built with a gain of 4, and a 15pF compensation cap, below a gain of 8, to eliminate ringing on a 100KHz square wave.  It slows the amp down, but no biggie, to me anyway.  I don't know if the EHHA A needs it.  You'd need a simulation or a scope measurement to be sure.
   
  Even the B22 needs a change of compensation caps for different gains.


----------



## BoilermakerFan

How much power do the K1Ks really need?  You could probably push 4W per channel out of a SE EHHA RevA with 2-1/2" heat sinks if you bump a few resistors up to 1/2w and 1w values and tweak the PS caps a little.  The trafo would need to be bumped up and it will be burning off more voltage at the V-regs if the load isn't there so they need to be on 2-1/2" sinks too.  But a balanced EHHA will be easier to setup and dial in than a balanced Bijou.


----------



## keyid

Quote:


> I agree!  That has given me the idea to acquire some SS or copper tubing and use an abrasive blade to kerf out about 2/3 of one half so it would look similar to the binder, but be solid metal.  Soft copper tubing could be bent to shape first too.


 

 im planning on doing this, tried this on another build and removed hum from over exposed wire.


----------



## stringgz301

Question: if one were going to build a balanced version of the Rev A amp,  what spec would you use for a SumR transformer?


----------



## jdkJake

stringgz301 said:


> Question: if one were going to build a balanced version of the Rev A amp,  what spec would you use for a SumR transformer?





 


Same voltage, double the current. Or just use two of them.

Depending upon your AC line in, you might want to go a bit lower on the 30-0-30 secondaries. What does your AC normally measure? Closer to 115VAC or 120VAC?


----------



## stringgz301

Actually a touch above 120v AC (120.3).


----------



## gurubhai

Quote: 





boilermakerfan said:


> How much power do the K1Ks really need?  You could probably push 4W per channel out of a SE EHHA RevA with 2-1/2" heat sinks if you bump a few resistors up to 1/2w and 1w values and tweak the PS caps a little.  The trafo would need to be bumped up and it will be burning off more voltage at the V-regs if the load isn't there so they need to be on 2-1/2" sinks too.  But a balanced EHHA will be easier to setup and dial in than a balanced Bijou.


 
  How does one calculate how much power EHHA outputs?
  Can someone point me towards the calculations required.


----------



## jdkJake

stringgz301 said:


> Actually a touch above 120v AC (120.3).






Based on a quick look, I think the main discussion on the topic was around post 830 or so. Might want to go back and peruse a bit. You have the possibility of going a bit lower if you want.

At that line voltage, the sumR seems to be coming in around ~38VAC at the regulators. A bit higher than the 35-36VAC Alex recommends. However, it does give you a bit more headroom for additional load components (like an e12) and a higher MOSFET bias. Also generates a bit more heat.

Were you not getting about ~39VAC with your Avel? Should be comparable or less than that. How are you getting along with that part?


----------



## holland

Quote: 





gurubhai said:


> How does one calculate how much power EHHA outputs?
> Can someone point me towards the calculations required.


 

 I don't know if it's been measured, to be honest.  The voltage swing should be about 43Vpp to 45Vpp, about 16Vrms, unloaded.  Current output in class A should be about 200mA.  This does not mean that you will achieve this into an arbitrary load.  Into a 32-ohm load, the voltage swing will be limited, as it will likely clip around 35Vpp to 40Vpp.
   
  The best way is to measure, but it will be a significant amount of power.  If you bias to 160mA, it will be at the B22 level of power output.  With the default 100mA, it will be less of course.
   
  Are you looking for something in particular?


----------



## gurubhai

^A friend of mine asked if EHHA could power HE-6. According to my calculations HE-6 needs about 1.5Watts at 50 ohm to push it to SPL of 115dB. I suppose even a standard EHHA build should be able to manage that but wasn't sure. So, I thought I should better ask.
  Amb's site has B22's measured power output as 5.4W at 32 ohms BTW.


----------



## holland

Quote: 





gurubhai said:


> ^A friend of mine asked if EHHA could power HE-6. According to my calculations HE-6 needs about 1.5Watts at 50 ohm to push it to SPL of 115dB. I suppose even a standard EHHA build should be able to manage that but wasn't sure. So, I thought I should better ask.
> Amb's site has B22's measured power output as 5.4W at 32 ohms BTW.


 

 You'll need about 175mA output (within the standard bias, but I would push it up anyway to 160mA with additional heat sinking), and about 8.7Vrms (24.6Vpeak to peak) to hit 1.5Wrms.  If the 1.5W is peak and not rms, then it's only 8.7Vpeak to peak, which is not much.
   
  With a 2Vrms source, you should be able to hit that with a gain of 4.3.  With a gain of 8 you should be able to hit the maximum power output of the amp with a 2Vrms source.


----------



## gurubhai

Quote: 





holland said:


> You'll need about 175mA output (within the standard bias, but I would push it up anyway to 160mA with additional heat sinking), and about 8.7Vrms (24.6Vpeak to peak) to hit 1.5Wrms.  If the 1.5W is peak and not rms, then it's only 8.7Vpeak to peak, which is not much.


 

 I understand that I would need about 175 mA into 50 ohm from my ohm. The question is can a stock EHHA( Gain9, bias: 100mA) output that?
  Do you mean that I have to push the bias upto 160mA to achieve this current output ?
  What is the relationship between bias current & power output of the amp ?


----------



## holland

Quote: 





gurubhai said:


> Quote:
> 
> 
> 
> ...


 

 Answered your first question in my response, bolded for you.
   
  No, you don't have to set it to 160mA, but bias is a tricky thing.  It's temperature dependent, and will move around a bit, so it's largely a "ballpark" thing.
   
  The EHHA is classic push-pull, so the quiescent/bias current for the output stage would allow it to remain in class A for ~2x the quiescent current.  200mA for the default settings.  320mA at the 160mA quiescent current configuration.
   
  Power = Voltage * Current
   
  The relation between the bias current and the power output is secondary.  The bias current is for class A operation.  EHHA is push-pull, so it is class AB, with a class A bias.  Once the bias is exceeded, the amp operates in class AB, but we are talking large amounts of current here, and likely will not be noticed.  Class A operation is for reducing crossover distortion.
   
  You need to size your heatsinks for the quiescent current operation, and you need to size your power supply, but I believe the default transformer recommendation is fine for 160mA quiescent current.  You will likely want to add some headroom in your transformer sizing if you're going to be bumping up against that often.
   
  Also note that you can easily do a balanced/bridged build also.


----------



## gurubhai

Got it now. Thanks for explaining
	

	
	
		
		

		
			





.


----------



## BK_856er

Got behind schedule on my EHHA casework, but I made some good progess this weekend!  Got all the holes where I wanted them, tapped everything and screwed it all together.  Still need to do the final wiring.  I may backmount the headphone jack if I can figure out a good way to remove some material from the back of the front plate.  Special thanks to jdkjake for his support!  This is still my first real build, so If anyone sees any issues please speak up.
   
  BK


----------



## johnwmclean

I can see something, I can see you’ve got loads of talent...
   
  There are safety covers available for the SSR, just a thought.


----------



## BK_856er

Quote: 





johnwmclean said:


> I can see something, I can see you’ve got loads of talent...
> 
> There are safety covers available for the SSR, just a thought.


 


 Thanks for the kind words!  I'm learning lots and having fun.
   
  Yep, got the ssr safety cover ready to go for power-up.
   
  Found a technique to hog out the back of the front panel so I could back-mount the headphone jack.  Took a couple hours, but it was worth the effort.  NOW it looks right to me.
   
  BK


----------



## jdkJake

Looking great BK!

Are you going to attach safety ground to the chassis at the back foot by the IEC?

What did you end up using to hog out the material on the back of the front panel?


----------



## BK_856er

Quote: 





jdkjake said:


> Looking great BK!
> 
> Are you going to attach safety ground to the chassis at the back foot by the IEC?
> 
> What did you end up using to hog out the material on the back of the front panel?


 


 Thanks!
   
  Absolutely - safety ground will connect to the bolt attaching the rear left foot near the IEC (after scratching away the anodizing).
   
  Dremel + flexible extension shaft + conical carbide bur tool from mcmaster carr.  The freehand aspect felt like dentistry and it was slow going, but it turned out better than I could have hoped.  The grinding stones that came with the dremel kit were useless because they loaded up with aluminum in short order.  The rotary bit made all the difference (#42955A46).
   
  BK


----------



## sachu

Love seeing new EHHAs being built...Your LCD_2 is gonna be mighty happy. What tubes you plan on running BK? And yeah, looking good dude.


----------



## BK_856er

Quote:


sachu said:


> Love seeing new EHHAs being built...Your LCD_2 is gonna be mighty happy. What tubes you plan on running BK? And yeah, looking good dude.


 


  Tubes?  The nos GEs you sent me a couple months ago!  
	

	
	
		
		

		
		
	


	



   
  Still keeping my eyes out for some telefunken...
   
  BK


----------



## sachu

doh..right..lol
   
  Try out the 6N27P..from waht stringzz tells us they sound promising..no pun intended


----------



## BK_856er

Quote: 





sachu said:


> doh..right..lol
> 
> Try out the 6N27P..from waht stringzz tells us they sound promising..no pun intended


 

 Are the 6N27P taller?  By eyeball I only have about 5mm clearance to the case cover (using short 10mm standoffs for the boards to allow for under wiring).
   
  BK


----------



## stringgz301

6N27P's have same physical dimensions as 6GM8.


----------



## jdkJake

bk_856er said:


> Dremel + flexible extension shaft + conical carbide bur tool from mcmaster carr.  The freehand aspect felt like dentistry and it was slow going, but it turned out better than I could have hoped.  The grinding stones that came with the dremel kit were useless because they loaded up with aluminum in short order.  The rotary bit made all the difference (#42955A46).
> 
> BK





 


Interesting. I used a similar bit (dremel #194) and the depth guide to set the cut depth. What did the flexible extension shaft bring to the party?


----------



## BK_856er

Quote: 





jdkjake said:


> Interesting. I used a similar bit (dremel #194) and the depth guide to set the cut depth. What did the flexible extension shaft bring to the party?


 

 My bit was conical and pointed at the tip, so I needed to present it horizontally in order to remove material.  The flexible extension allowed me to achieve a narrow angle of attack.  Your cylindrical, flat-bottomed bit is much better suited for a job like this, more like a router, but I was limited to what I could scrounge up late Sunday night.  Could not rest until I got that jack properly mounted jk style!  I really dig those bur bits - need to get a full set with different shapes...and a depth guide.
  
  BK


----------



## jdkJake

Quote: 





bk_856er said:


> My bit was conical and pointed at the tip, so I needed to present it horizontally in order to remove material.  The flexible extension allowed me to achieve a narrow angle of attack.  Your cylindrical, flat-bottomed bit is much better suited for a job like this, more like a router, but I was limited to what I could scrounge up late Sunday night.  Could not rest until I got that jack properly mounted jk style!  I really dig those bur bits - need to get a full set with different shapes...and a depth guide.


 

 I hear that! 
	

	
	
		
		

		
			




   
  I love my dremel. I have no idea why I waited so long to get one. Over the past year or so, I have used it for all kinds of work. The cutting wheels work great for square cuts. I used them (finished with a file) for my power switch and IEC inlet. Good stuff!


----------



## nullstring

Has anyone listened to both the EHHA and the EHHA Rev A?
   
   
  For some reason I have a hard time ordering until I know how the two revision compare.
   
  I expect they are more or less the same, but I'd like someone to confirm that.


----------



## gurubhai

They both sound fantastic & yes, pretty similar.


----------



## BK_856er

My intention is to wire up the EHHA revA according to the alternate wiring scheme.
   
  I have Belden 8451 (22ga, two-conductor, foil shielded, drain wire) to be used between the isolated Neutrik jacks and the TKD potentiometer, and between the potentiometer and the board.
   
  Output signal to the dual AMB e12s and headphone jack will be with single conductor 24ga shielded coaxial cable from navships.
   
  Should I connect the Belden drain wire somewhere to optimize shielding?
   
  Similarly, should the mesh shielding of the navships coaxial output wiring be connected anywhere?
   
  Some pics below for reference.
   
  BK


----------



## stringgz301

Need some advice.  I want to convert my EHHA Rev-A build to balanced.  Question is what to do about transformers.  As some of you may remember, I used Avel-Lindberg transformers in my build and have been pretty happy with them.  Trying to figure out the best path for a balanced conversion.
   
  Option 1: swap out the AL 30VA 30+30 .5A secondary for an AL 63VA 30+30 1.05A secondary, and the AL 15VA 9+9 .83A secondary for an AL 30VA 9+9 1.67A secondary
   
  Option 2: just duplicate the existing transformers so that there are 4 total in the case
   
  Option 3: have SumR build a custom transformer with 9V secondaries
   
  Option 4: double the spec'ed current on the sumR transformer others have used (with 7V secondaries) and swap out the diodes on the 2 existing boards to use the lower voltage
   
   
   
  Thoughts?  Don't really like Option 2 because it will be a wiring mess.  Not sure if option 1 will work given that the new transformer is not a direct doubling of the original.


----------



## holland

Quote: 





stringgz301 said:


> Need some advice.  I want to convert my EHHA Rev-A build to balanced.  Question is what to do about transformers.  As some of you may remember, I used Avel-Lindberg transformers in my build and have been pretty happy with them.  Trying to figure out the best path for a balanced conversion.
> 
> Option 1: swap out the AL 30VA 30+30 .5A secondary for an AL 63VA 30+30 1.05A secondary, and the AL 15VA 9+9 .83A secondary for an AL 30VA 9+9 1.67A secondary
> 
> ...


 

 Option 1 or 3, as Option 4 is basically the same.  If you're ordering custom you might as well get what you want/need.  Option 1 should be fine.
   


  Quote: 





bk_856er said:


> Should I connect the Belden drain wire somewhere to optimize shielding?
> 
> Similarly, should the mesh shielding of the navships coaxial output wiring be connected anywhere?


 
   
   
  It's safe/fine to connect all the shields to star ground.  I connect the input shield to the input ground (which is tied to star ground later).  Do not connect the other end of the shield to input ground.  Connect it only at one end at the jack (or a wire to star ground).  After it goes to the pot, the wire from the pot goes to the amp board...the shield on that wire, tie it to the shield on the input wire, as if you broke the shield at the pot.
   
  Output wiring, connect the shield to star ground, but only at the point of exit from the amp.  As with input, leave the end floating.


----------



## sachu

stringz, drop me a line and i'll give you some info on what to do for the transformer on the cheap...atleawst for the HV.


----------



## jdkJake

stringgz301 said:


> Option 1: swap out the AL 30VA 30+30 .5A secondary for an AL 63VA 30+30 1.05A secondary, and the AL 15VA 9+9 .83A secondary for an AL 30VA 9+9 1.67A secondary





So, based on my observations and measurements, if you go with option 1, I think you could actually go with the 50VA 830mA Y236207 part and be perfectly fine. Especially in light of your AC line voltage readings. 

Of course a custom transformer is just that, whatever you want it to be. Just depends if you want to spend the extra cash.

BTW, personnel message from an old local, GO PACK GO!!!


----------



## nullstring

Hey guys,
   
  What modifications to the Heater supply schematic need to be made if it is to run two tubes in parallel? (double the current)
   
  I assume the only reason it is divided into two Heater supplies is the simplicity of adding it to the end of the PCB.
   
  I am planning building an original EHHA + sigma 22.
  I also plan on protoboarding the heater supply for the EHHA Rev A.


----------



## sachu

Just build both the heater boards for 6.3V and run one tube with each.


----------



## nullstring

Yeah, I just found some information on DC filament supplies.
  In that information is suggested you use one supply per tube. (I swear, everytime I ask a question I figure out how to answer it myself. "DC filament supply" was the keyword I needed)
   
  Anyway... It looks like I have alot of options as far as supplies go.
  Sachu, I believe you have DC filament supplies on your original EHHA? What power supply did you go with?


----------



## sachu

Filament supplies as i made the mistake nearly two years ago now is for the filament in DHTs.
   
  The one i used was the Pete millet design which just uses the LDO LD1085 same as the heater supply on the EHHA Rev A.


----------



## dBel84

A simple way to get high current heater supply is to use a high power opamp ( in a TO220 package or similar ) , I have started to default to this method and make an adjustable supply for any tube project - it is pretty simple to breadboard and offers more then the 1A limit of the LM317/337 LDO's. Of course there are 3A LDOs too but I have a box full of chips and no plans to build gainclones so it is a biased decision for me..dB


----------



## BloodInside

Finally had some time to work on my EHHA again today and screwed it up big time. The first board went up and running great, but I accidentally swapped the +30V and -30V wiring on the second board. The result: smoke coming from Q1. Immediately turned off the power and saw the wrong wiring. 
   
  I fixed the wiring and applied the power again and it seems that the servo isn't functioning anymore. I'm measuring around 0,4V DC across the OUT and GROUND and it isn't stabilizing. 
   
  Do you guys have any pointers on how to proceed?


----------



## jdkJake

Well, if you smoked it, you will certainly need to replace Q1. Good place to start.

I would also check the output of the 78L15/ 79L15 regulators and make sure they are still putting out +15/-15 respectively. 

Are the MOSFETs biasing?


----------



## BloodInside

Thanks for your response.
   
  The 79L15 regulator is putting out -2.9 volts and the 78L15 regulator is putting out 20.67 volts. I measured those voltages on the opamp pins 4 (for the 79L15) and 7 (for the 78L15) to the ground.
   
  So they are probably toasted as well? Judging from the maximum rating of +/- 18V on the opamp, that one is probably smoked as well.
   
  The testpoints on the BJT's measure -0.005 volts (TP2) and 0.000 volts (TP1). Turning the BIAS pot doesn't make any difference, so I assume the bias mechanism is broken as well. 
   
  I'm also measuring around 5.332 volts DC output now. Quite a difference from yesterday when I just blew them.
   
  So far I should at least replace Q1, V+, V- and the TL081. Any more suggestions before I place my order?


----------



## runeight

Order all the sand in the output section, both O/P devices, the two Vbe devices, and the follower drivers, some opamps, and more than one of each regulator.
   
  Given that power was reversed everywhere many of the other transistors might be toasted too. Since they are so cheap I would order replacements for all of them just in case. And maybe even another CRD.


----------



## BloodInside

Thank you for your support. I've just placed the order, probably will get all the components within two weeks. 
   
  At least now I know what price you pay when you hurry things... A good lesson for next time.


----------



## BK_856er

Quote: 





holland said:


> Quote:
> 
> 
> 
> ...


 


 Thanks for the details!  I followed the concept of connecting only one end of the input/output shielding to star ground, while leaving the opposite end floating.  I hope it won't be an issue, but I made the RCA jack and the board the floating ends for the input and output wiring, respectively.  Below you can see the bare drain wire going to star ground and also the connected shielding at the pot.
   
  Wish me luck....first powerup with final case and wiring tomorrow when my brain is fresh!
   
  BK


----------



## BK_856er

Mission accomplished.  Sounds wonderful!  Very detailed, engaging, nice bass impact.  Critical listening to come later.
   
  Just a few minor things to sort out:
   
  - mixed up the RCA jack colors
  - bulgin dual-color switch driven by an e24 glows red and not blue
  - need to figure out a method to mount the e24 overtemp sensor
  - slight buzz (none at min volume positions, but is constant throught rest of travel, decreases when touching the casework)
  - will verify bias after things run in for a few hours - case is staying nice and cool
   
  The new v2.0 e12s seem to work great.  Mutes the output for 30sec on startup.
   
  With sensitive test headphones only ~10% pot travel is used.
   
  I really underestimated what it would take to go from powered mockup in a cardboard box to the final product.  Lots of late nights doing up all the wiring and casework.  Very satisfying in the end.
   
  BK


----------



## sachu

nice work 
   
  when you get some hadtime on it..curious to some comparisons against the V200


----------



## BK_856er

Quote: 





bk_856er said:


> Quote:
> 
> 
> 
> ...


 

 Just to follow up this detail...I checked with Ti just now and he says at +/-30V the TO-92 slip-on heatsinks are a good idea for Q1 and Q2 on the latest v2.0 e12.  I had some on hand and installed them.
   
  BK


----------



## BK_856er

I have now resolved all the small outstanding issues with my build, so I'm declaring victory on this one.
   
  The buzz with certain sources connected turned out to be far more problematic than I first thought (after the initial euphoria of a working amp wore off).  Huge thanks to my mentor jdkJake for patiently walking me through all the trouble-shooting steps via numerous pm and ultimatley suggesting a ground loop breaker.  The ground loop breaker totally solved my buzz issue.  Should this be standard?
   
  Now to get down to business and really get to know this most excellent amp.  
	

	
	
		
		

		
			




   
  BK


----------



## dBel84

I routinely do not install one in my builds, but it is the very first thing I do if there is buzz because it is a much more accessible fix than most others when it comes to tackling hum. My EHHA ended up with one, my SOHA II did not etc ..dB


----------



## holland

I always install a ground loop breaker as part of my ground bus, using a diode bridge, a cap, and a resistor.  It's harder, sometimes, to fix it after the fact.  You'll see it when I post up my EHHA I pictures soon...almost done with the casework.


----------



## BK_856er

Quote:


holland said:


> I always install a ground loop breaker as part of my ground bus, using a diode bridge, a cap, and a resistor.  It's harder, sometimes, to fix it after the fact.  You'll see it when I post up my EHHA I pictures soon...almost done with the casework.


 

 Sounds like there is more than one way to do it.  I'll be watching out for the pics.  A new thing I noticed is a little pop through the headphones on power-off.  I usually turn the volume pot all the way down before powering off, but this time I forgot.  I'm assuming it's related to the new grounding scheme.  If a different ground loop breaker setup helps with that I'll definitely give it a try.
   
  BK


----------



## dBel84

This pop is most likely a small amount of offset as the amp powers up / down and the rails settle. ( ie before the servo has chance to control the offset and zero it ) My general recommendation is to always remove headphones before switching off / on an amp. Some headphones are more sensitive than others but prolonged exposure to 1-2V ( even for a few seconds ) cannot be a good thing. Some people use the offset sensing circuit that AMB released ( the epsilon 12 ) while others use a more simple relay to cut the output at power up / down (Millet max etc amps) . Personally, I unplug my headphones after every session..dB


----------



## johnwmclean

Quote: 





bk_856er said:


> Quote:
> 
> A new thing I noticed is a little pop through the headphones on power-off.  I usually turn the volume pot all the way down before powering off, but this time I forgot.  I'm assuming it's related to the new grounding scheme.  If a different ground loop breaker setup helps with that I'll definitely give it a try.
> 
> BK


 

 Why? I see you have epsilon 12s installed so this shouldn’t be a problem.


----------



## BK_856er

Quote:


dbel84 said:


> This pop is most likely a small amount of offset as the amp powers up / down and the rails settle. ( ie before the servo has chance to control the offset and zero it ) My general recommendation is to always remove headphones before switching off / on an amp. Some headphones are more sensitive than others but prolonged exposure to 1-2V ( even for a few seconds ) cannot be a good thing. Some people use the offset sensing circuit that AMB released ( the epsilon 12 ) while others use a more simple relay to cut the output at power up / down (Millet max etc amps) . Personally, I unplug my headphones after every session..dB


 

 I already have dual v2 e12s installed.  The rails might be discharging faster with the loop breaker installed (?) and the relay therefore can't open fast enough, so I get a slight pop on power-off.  I'll verify the e12 offset setting to see if it's changed since I added the breaker.  Unplugging the headphones is probably a good practice.
  
  BK


----------



## dBel84

missed that sorry, the e12 is pretty fast, make sure that the ground loop hasn't affected it's center point. I had this problem in one build and had to remove the e12 virtual ground and ground it to the amp  - afraid I am not a huge fan of the e12 but I do see the value in it..dB


----------



## BK_856er

Quote: 





johnwmclean said:


> Why? I see you have epsilon 12s installed so this shouldn’t be a problem.


 


  See previous post.  Just speculating...e12 relay no longer opens fast enough on power-off with the new grounding scheme.  AMB describes a supplementary mechanical switch for similar situations. Just to clarify, the turn-off pop is very minor.
   
  BK


----------



## johnwmclean

DELETE..


----------



## BK_856er

Quote: 





johnwmclean said:


> You shouldn't have any turn on noise with the e12, the relays should click in after a few seconds.


 

 Right - there is zero turn-on noise.  The v2 e12s mute the output for a full 30sec during turn-on, and startup is very graceful.  The little pop I'm describing is at power-off via the e24 circuit.
   
  BK


----------



## johnwmclean

You were too quick for my edit, I unsterstand now.

I have a similar problem, I've captured 2.4V worst case, I'm using 300R phones therefore 2.4/300 = 8mA, no real issue here.

But as stated there's nothing like the insurance of unplugging your phones.


----------



## funch

FYI, I also get a pop (or did the one time I left the 'phones plugged in) on power off with my SOHA II.


----------



## cfcubed

WRT e12 pop @ release - Pretty sure this has been discussed before & is a bit OT, but speaking from working w/it on the CTH, yes there is a bit of a pop.  But it is extremely brief & not large - try "watching" it w/DMM or scope, so I decide not to pull the phones.  I just remove the cans from my head then power off, less wear on jacks, etc.  But we all make our choices.
  There may be other ways, but one way for certain to eliminate the pop is to interrupt the e12 power @ same time as amp power (e.g. through a double-pole power switch, or whatever Ti recommends of course).  I've done this on my "fancy" CTH by breaking a relay power trace on the PCB & bridging the gap w/one pole of a DPDT power switch.


----------



## runeight

A small amount of pop is unavoidable when using an e12 with many direct coupled amps, depending on how their DC offset is managed. The e12 has a reasonably rapid response time but it can't be instantaeous or it would be tripping during normal listening. When the power is shut off the amp slews pretty quickly and starts to put DC onto the headphones. The diaphragm is pulled to one side. The e12 then either detects or simply disengages due to lose of power. The pop is the diaphragm popping back to its normal position.
   
  The response of the e12 is normally fast enough so that, while there is a small pop, it is not more current than the headphones can handle. Usually way less.
   
  But, the absolute guarantee is to pull the plug from the jack before power down.


----------



## BK_856er

Re-adjusting the v2 e12s zero setting after adding the ground loop breaker seems to have taken care of my small power-off pop through the headphones.  The e12s required very little adjustment.  Now I only hear a faint tick through the headphones during power-off, which is what I recalled initially.  Essentially nothing.  Not too shabby.
   
  Logging lots of hours with the new amp every day.  Very satisfying.
   
  BK


----------



## funch

I'm getting ready to order a kit from Jeff, and thought I'd chime in with some observations of the tubes I got from AES
  and posted in the other EHHA thread (p. 96, post #1428). I inspected the five tubes very closely and found the following:
   
  1. 4 of the tubes were made in Holland, 1 in Germany.
  2. The Amperex German tube is very different on the top than the Holland tubes.
  3. The Bugle Boy and Amperex tubes, both made in Holland, are identical to each other.
  4. The Admiral and GE tubes, both made in Holland, are identical to each other also.
  5. Pair 3 is almost identical to pair 4, with only a couple of minor differences between them.
   
  So it appears that I have two matched pairs, but we'll 'hear' how that turns out.
   
  FWIW


----------



## funch

This is question for Jake or BK. What's the best way to order a case from Par-Metal? I've used their cases in two other builds, but always got them from
  the Antek ebay store. Also, how much more did they charge to put the extra row of slots in the top, and do you think it's worth it? Thanks.


----------



## BK_856er

Quote: 





funch said:


> This is question for Jake or BK. What's the best way to order a case from Par-Metal? I've used their cases in two other builds, but always got them from
> the Antek ebay store. Also, how much more did they charge to put the extra row of slots in the top, and do you think it's worth it? Thanks.


 

 I took jk's lead and used a third row of vent slots on the Par-Metal case - no regrets.  I simply ordered via the Par-Metal web page and requested a third row of vent slots in the comment section.  I never heard back, but the case showed up on schedule and as expected.  No extra charge for the extra slots.  I think the added ventilation is nothing but good.  BTW, the extra slots are on both the top and bottom.  I'll probably phone in my next order.  Very pleased with the product/service.
   
  BK


----------



## holland

I have always ordered via email, when I want something in particular, and send a paypal after, unless I am requesting a quote.  Things just show up, general communication is not that great, but I'm used to it from Antek.


----------



## funch

Thanks, guys. I just ordered from their website. Thought I might try one of their thicker faceplates too.


----------



## jdkJake

bk_856er said:


> I took jk's lead and used a third row of vent slots on the Par-Metal case - no regrets.  I simply ordered via the Par-Metal web page and requested a third row of vent slots in the comment section.  I never heard back, but the case showed up on schedule and as expected.  No extra charge for the extra slots.  I think the added ventilation is nothing but good.  BTW, the extra slots are on both the top and bottom.  I'll probably phone in my next order.  Very pleased with the product/service.
> 
> BK




What he said.


----------



## BK_856er

Been spending lots of quality time with the amp these past few weeks, probably 2-3hrs most nights.  Good times.
   
  Found it a bit flat with vocals, a bit distant, lacking some magic.  Decided to leave it powered on for 72hrs solid, alternating between Bach violin concertos and Guns&Roses playing to the LCD-2 at moderate volume.  The amp really seemed to benefit from this treatment.  Not sure if it was Hilary Hahn or Axel Rose that did it, but me like.  Terrific amp.
   
  Tonight I fine tuned the mosfet bias to 220mV (several hours on and in use, cased up, made the adjustments immediately after removing the cover).  I adjusted the trimpots a few times, with ample time for them to thermally settle between tweaks, to get the bias at a consistent 220mV under truly normal operating conditions.  The value really is sensitive to the temperature.
   
  Noticed the casework top was a good bit hotter.  Mosfet heatsinks are quite hot to the touch - can only maintain momentary skin contact.  My cheapish DMM wire type thermocouple measures 36C above ambient on the top of the heatsink.  I don't trust the absolute number, but the delta is probably decently accurate.  Assume 24C room temperature, then that's about 60C at the heatsink.  Stuck a lab type immersion thermometer against the heatsink and got about 50C, but that's almost certainly low because of the non-ideal contact with an improper measuring device.
   
  Process and 60C mosfet heatsink temps OK?
   
  BK


----------



## johnwmclean

[size=12.0px]60C over those devices should be ok, it is on the hotter side but well within spec.

 Biasing after two hours or so of music the FETS would be working at their most efficient, the mA reading would be at it’s lowest. I could be wrong here but my understanding was to leave the amp at idle (no music) for approx 1/2 an hour or so then bias.  [/size]


----------



## BK_856er

Quote: 





johnwmclean said:


> 60C over those devices should be ok, it is on the hotter side but well within spec.
> 
> Biasing after two hours or so of music the FETS would be working at their most efficient, the mA reading would be at it’s lowest. I could be wrong here but my understanding was to leave the amp at idle (no music) for approx 1/2 an hour or so then bias.


 

 Thanks for the info.  I tested again today after a couple hours idle from powerup and they were only up around 230mV, so I readjusted to 220mV a couple times just to be safe.  I couldn't find any additional setup specifics at the Cavalli site, so I presume the protocol is not super critical and I'm now good to go.
   
  Found this article helpful for an electronics newb like me.  Mosfets themselves seem to be able to tolerate quite a lot of heat!
   
http://jeelabs.org/2011/02/06/easy-electrons-%E2%80%93-mosfets-and-heat/
   
  BK


----------



## johnwmclean

Nice one, you seem to have a very stable amp.
   
  Like you say the protocol for biasing is not highly critical, but I’ve never been able to find a thorough procedure on the do’s and don’ts.
   
  However I would still argue that 2 hours is excessive, without any input signal the devices would therefore become inefficient, the opposite to playing music. I still think 20 - 30 minutes would be the optimum time for the fet’s to stabilize under idle conditions.
   
  I’m no expert on the subject and would love find out more on the subject to better my understanding.


----------



## sachu

a 30 minute warm up is mandatory for all tube and hybrid components.
   
  I never listen to any amp that i own expecting it to sound good after a cold start.


----------



## Horio

Seems like the old EHHA thread is mostly dead these days, so I thought I post here.  I'm setting up my balanced build using the original boards.  When I bias the amp up to 100mA (0.22V), I notice that the left heatsink (Q8M) becomes very hot after just a few minutes while the right heatsink (Q9M) stays much cooler in comparison.  I would think the two should be pretty similar.  Anyone else run into this when setting up their amp for the first time?


----------



## holland

no, but you you can measure currents across both resistors and note the variance.


----------



## Horio

That is the interesting thing.  I measured the voltage across both source resistors, and they both measured right at 0.22V.


----------



## holland

that is interesting.  mine is not even, varies by about .30mV, but perhaps you have better matches.


----------



## Horio

My voltages on the front end are all a bit low too.  So something is definitely off, but I'm really struggling to figure out what.  I emailed Alex for backup...


----------



## sachu

Hmm..can you measure the voltages at R24 and R25 wrt GND?
   
  Also check your rail voltages..report back what you measure.
   
  What devices are you using on Q8 and Q9?


----------



## Horio

Here are some values for 2 of my boards (without the opamp installed):
   
  R24 = 3.80V/4.13V
   
  R25 = 1.22V/0.91V
   
  Q8 = IRFZ24N
   
  Q9 = IRF9Z34N
   
  The voltage coming out of my o22 is +/-29V.  Where is a good point to measure the rails (sorry I'm still learning).  If I try to measure from star ground to one of the rails I get this:
   
  -30V power input terminal w.r.t. star ground = -11.1V
   
  +30V power input terminal w.r.t. star ground = 46.9V


----------



## holland

is your o22 connected to the star ground?  star ground is the ground to use.  the o22 ground should connect to star ground.  double check your wiring so you don't blow something up.
   
  when you test your o22, how are you testing the voltages?


----------



## Horio

Wow...I can't believe I overlooked that.  Well fortunately nothing blew up, and now magically all my front end voltages are making sense now.  I guess that's what I get when my table looks like a birds nest...
   
  So I've adjusted R6 and now I have:
   
  R24: 1.49V/1.49V
   
  R25: 1.52V/1.53V


----------



## sachu

heh..nice..yeah those measuremnets really helped nail it down.
   
  The voltages on the gates are a little low if you ask me ..with those voltages at R24 and R25 you are reading 220mV across the output resistors?


----------



## Horio

Those voltages were before I brought up the bias.
   
  I finished the checks last night, brought up the bias, and put in the opamp.  Seems like all (4) boards are running great.  Just waiting on FPE to finish my panels.


----------



## funch

Lookie! Such a 'great deal' on a pair of 6GM8's. http://cgi.ebay.com/40-YEAR-OLD-MINT-NOS-ECC86-6GM8-AMPEREX-GERMAN-TUBES-/190508609064?pt=Vintage_Electronics_R2&hash=item2c5b32ae28  Sure hope this isn't where prices are heading.


----------



## sachu

Holy crap..am asking waaay too less for my telefunkens.. lol i think i'll just keep them


----------



## funch

So, how did you like the Tele's?


----------



## sachu

They are the best I have heard in the EHHA. 
   
  Amperex bugle boys are lusher but glosses over details. Valvos have a more full on midrange but a little too warm for me, Amperex and GE marked amperexs are run of the mill..don't do anything wrong but don't do anything exceptionally either. 
   
  The Teles are just smooth and crystal clear with just enough of that tube warmth to pull you in.


----------



## BK_856er

I need to get me a set of Teles and/or Valvos.  I'm thrilled with my EHHA Rev A and GE Amperex tubes, but I think there's more potential in there.
   
  BK


----------



## stringgz301

I tried a pair of GE/Amperex a-frames that jdkjake sent me (thanks Jake!) and overall found the soundstage good and nice warm mids.  However I didn't like the highs (cymbals sounded harsh) and the bass was soft.  Overall I've found that preferred tubes depend on the phones I'm using:
   
  - with LCD-2's, the Tele's are spot on. Very solid deep bass, shimmering highs, very nice soundstage.  Tried the 6N27P's and they sounded a little thin.
   
  - with HF-2's, the 6N27P's won.  Big soundstage, great balance top to bottom and very accurate in terms of instrument positioning. Great complement to the Grado's.  The Tele's were just a little thick in the upper bass and low mid's.
   
  This weekend the Rev A is getting converted to balanced.  Should be interesting to see if this changes my opinions at all.  I've got quads of Tele's and 6N27P's on deck.  Am also converting from TKD pot to Khozmo attenuator.
   
  Stay tuned.


----------



## jdkJake

I have been running with a set of the tele's for a few weeks now. They took a while to wake up from their slumber, but, finally settled into their grove.
   
  For now, I have mixed opinions on the tele's. They certainly capture your attention with their detail and sense of space. However, they seem have a more forward presentation, which, works better with some material than others. Certainly a most impressive sound and very different from the Amperex A-frames I had been using. Worth a listen to see if it is your cup of tea. I find I like them much better with my HD650's than with the HF-2's.
   
  I picked up a quad of 6N27P's. I am also hoping the 6N27P's are a more  in-between presentation; not as forward as the tele's nor as laid back as the Amperex. Hopefully I will get a chance to audition them soonest.


----------



## stringgz301

Jake - don't forget to give the 6N27P's at least 48 hours of burn-in.  They change pretty dramatically during that period.


----------



## jdkJake

stringgz301 said:


> Jake - don't forget to give the 6N27P's at least 48 hours of burn-in.  They change pretty dramatically during that period.




Will do. 

Thanks for posting your listening results with the Amperex A-frames!


----------



## BK_856er

Question for the Telefunken experts.  Some are marked with white lettering as "Made in Germany" and a minority of others are marked as "Made in Western Germany."  Pics do not always adequately show the internals.  Is there more than one type of Telefunken 6GM8, and if so has anyone compared the sonic differences in the EHHA?
   
  BK


----------



## stringgz301

All of mine say Made in Western Germany


----------



## stixx

Since 1990 we only have one Germany...
	

	
	
		
		

		
			




   
  All Telefunken tubes were made in Western Germany (TFK was located in (West) Berlin...).


----------



## BK_856er

My supplier tells me the Telefunken labeled as "Made in Western Germany" are the older vintage and date back to mid '50s to mid/late '60s.  I received them today and compared the internal construction to some pics jdkJake provided of the later "Made in Germany" units, and they are identical as far as I can tell.
   
  I also have some Russian Reflektor 6N27P and "Made in Germany" Telefunken 6GM8 (later vintage) on the way for comparison.  Currently running Holland-made GE-labeled Amperex.
   
  Do I need to readjust the bias after installing the Telefunken tubes?
   
  BK


----------



## sachu

nope..they should come up right away


----------



## stringgz301

I found that the Amperex a-frames biased significantly differently from all my other tubes.  You may need to recheck it after installing the Tele's.


----------



## BK_856er

Quote: 





stringgz301 said:


> I found that the Amperex a-frames biased significantly differently from all my other tubes.  You may need to recheck it after installing the Tele's.


 

 Just pulled the cover and checked the bias after an overnight burn-in.  Measured 214mV and 216mV, so in this case things seem alright without re-adjustment.
   
  BTW, found a good digital Fluke thermocouple and the internal case temp is ~38C and the surface temp of the top of the warmest heatsink is ~49C.  Ambient temp is currently reading 21C.
   
  I like the Telefunken sound so far....
   
  BK


----------



## dBel84

I would be very surprised if the bias went off with a tube change, you may need to balance the tube sections but the output bias should be mostly impervious to tube changes unless the tube was failing..dB


----------



## gurubhai

I never had to change bias on tube rolling.
   
  BTW, has anyone else tried the E88CC on the rev. A?
  I didn't care for it on my EHHA build but it sounds fantastic on the rev. A.


----------



## foet

How do they sound compared to the - for example - telefunken 6GM8's?
   
  I've ordered a matched set of '70 russion military 6N27P for my EHHA rev A to be, and was wondering what would give me a balanced sound with my HE5-LE (that sound quite thin with my current DSP19-C2 combo). My only comparisons would be the standard tubes in the GJA kit if it ever arrives.

 Could someneone who has heared the lot could sum it up shortly? I understand tele's are just about as good as you can go 6GM8 wise, but compared to other types there seems to be litle info; especially these russian litle fellas.


----------



## stringgz301

If your headphones sound thin you probably want to go with Tele's (best) or halo getter Amperex (I have some relabeled Seimens like this).  The 6N27P's tend to be more analytical and focused.  I've actually listened to the HE6 through the EHHA-rev A with Tele's and it sounded very nice.


----------



## gurubhai

Quote: 





foet said:


> How do they sound compared to the - for example - telefunken 6GM8's?


 
  I switched from the tele's last week & haven't felt the urge to revert back.The jury is still out, but on my system the E88CC seems to perform at least as good as, if not better, than the telefunkens.
  I had earlier, clearly prefered the teles to Mulllard, Philco,Amperex Bugle Boy,amperex & GE ones.


----------



## stringgz301

Ok Guys.  Need help debugging my balanced EHHA.  All boards start up and bias properly (2 of them are from my original single ended EHHA in operation for months now).  However, I'm getting big hum (constant with a surge about every second).  It is on both sides.  I've disconnected the inputs to the boards (I and IG) and it is still there.  As a first debugging step I found that I have continuity between Out and SG when the boards are powered.  Is this normal?
   
  Any debugging suggestions?


----------



## jdkJake

What is the measured value between OUT and Signal Ground?


----------



## stringgz301

OK.  So solved one problem.  Had the rails transformer improperly wired.  Corrected this and started it up again.  Heater and rails power supplies test good, with corrected DC output from heater PS and rails PS.  DC offset 0.  Tubes bias properly.  
   
  Have a different hum.  Music plays ok, but when it stops have background hum.  Independent of volume pot.  Could this be the dreaded ground loop?


----------



## jdkJake

stringgz301 said:


> OK.  So solved one problem.  Had the rails transformer improperly wired.  Corrected this and started it up again.  Heater and rails power supplies test good, with corrected DC output from heater PS and rails PS.  DC offset 0.  Tubes bias properly.
> 
> Have a different hum.  Music plays ok, but when it stops have background hum.  Independent of volume pot.  Could this be the dreaded ground loop?




Maybe. How did you wire it up? Which grounds did you connect to star ground?


----------



## funch

I've just started my setup, and am having a problem with the heater supply. I'm using the tranny from the Glassjar kit, an Avel Y236101, 9VAC/1.65A.
  I've got it wired with the red/black wires to one board, and the yellow/orange wires to the other. Both boards are reading 13.65VDC at TP3, and the output
  is at 12.65VDC. I cannot get the output to change at all. Do I have the tranny wired wrong? Should I pair black/orange and red/yellow? Have I blown the reg's?
  I'm stumped.


----------



## dwh91307

I also used the Glassjar kit and experienced same problem with both boards.  I replaced both regs and all is fine now.  Perhaps bad batch of ld1085's.
  
  Quote: 





funch said:


> I've just started my setup, and am having a problem with the heater supply. I'm using the tranny from the Glassjar kit, an Avel Y236101, 9VAC/1.65A.
> I've got it wired with the red/black wires to one board, and the yellow/orange wires to the other. Both boards are reading 13.65VDC at TP3, and the output
> is at 12.65VDC. I cannot get the output to change at all. Do I have the tranny wired wrong? Should I pair black/orange and red/yellow? Have I blown the reg's?
> I'm stumped.


----------



## stringgz301

Grounding: right now, each board has 3 sg grounds (I'm using the alternate wiring scheme connection at the front of the board), that all connect to a central terminal.  That ground is isolated from the case (should it be?).  The IEC ground is connected to the case.  
   
  A bit of question mark for me is the Khozmo attenuator (4 channel).  It has 4 inputs plus a ground connector, and 1 pair per channel of output and ground connections.  I currently have it wired like the attached (Pic from john mcclean, my annotations, using wire leads instead of his diy bridge between ground connections).  Not sure why he has 2 leads connected to each output ground connection.  Also, not sure why the bridge is required given that on each board the IG connects through the ground plane to SG.
   
   
  Any and all help is much appreciated.


----------



## sachu

Quote: 





stringgz301 said:


> Grounding: right now, each board has 3 sg grounds (I'm using the alternate wiring scheme connection at the front of the board), that all connect to a central terminal.  That ground is isolated from the case (should it be?).  The IEC ground is connected to the case.
> 
> *Yes. That central terminal needs to be connected through a ground loop breaker to the chassis. Use a 10 ohm/10Watt wirewound resistor with a Class X or Class Y 250VAC capacitor.*
> 
> ...


----------



## stringgz301

Thanks Sachu.  Well it's definitely related to the input wiring, because when I disconnect the input and input ground from each board the amp is dead quiet.


----------



## funch

Quote: 





dwh91307 said:


> I also used the Glassjar kit and experienced same problem with both boards.  I replaced both regs and all is fine now.  Perhaps bad batch of ld1085's.


 

 Thanks for the input. I'll try new reg's.
   
Update:    Yep, that was it! New reg's and all is well. I wonder if Jeff did in fact get a bad batch of reg's?


----------



## johnwmclean

To clarify,
   
  Grounds are: 2 inputs, 4 amp boards, 2 speaker posts. The gound that you labelled “from input grounds” is actually the chassis ground connection.
  Quote: 





stringgz301 said:


> Grounding: right now, each board has 3 sg grounds (I'm using the alternate wiring scheme connection at the front of the board), that all connect to a central terminal.  That ground is isolated from the case (should it be?).  The IEC ground is connected to the case.
> 
> A bit of question mark for me is the Khozmo attenuator (4 channel).  It has 4 inputs plus a ground connector, and 1 pair per channel of output and ground connections.  I currently have it wired like the attached (Pic from john mcclean, my annotations, using wire leads instead of his diy bridge between ground connections).  Not sure why he has 2 leads connected to each output ground connection.  Also, not sure why the bridge is required given that on each board the IG connects through the ground plane to SG.
> 
> ...


----------



## stringgz301

Thanks John. So where did you connect the 2 input grounds? Also, my khozmo came with a wire bridge soldered between the middle and upper position for each output and ground position. Was yours different?


----------



## johnwmclean

[size=medium][size=13.0px]Yeah I’ve seen different variations.

 Apologises I’ve confused myself, scrap what I mentioned earlier as this was the attenuator for my Beta22 not my EHHA.

 Here’s an installation guide for unbalanced,
http://www.partsconnexion.com/prod_pdf/Khozmo_install.pdf

 The two input grounds can be connected to any of the ground pads, they should all be electrically shorted once you connect everything up, to ensure this I installed pins into each ground pad and with wire jumper, not conventional, and not really needed, but it worked for me, the amps as quiet as a mouse.

 Looking at the EHHA balanced wiring diagram Pin 1 is not part of the star ground, so wire accordingly.[/size][/size]


----------



## Jrossel

Quote: 





funch said:


> Thanks for the input. I'll try new reg's.
> 
> Update:    Yep, that was it! New reg's and all is well. I wonder if Jeff did in fact get a bad batch of reg's?


 


 Hi funch.  Sorry about the regulators.  Turns out I have a batch of fixed regulators by mistake.  Let me send you a refund for the cost.  Now I need to contact several other kit builders too, hopefully they are not pulling out too much hair in frustration.
   
  Jeff


----------



## funch

Here's mine.
   

   
  Nothing special. Kit from Glassjar. Par-Metal case with their 3/16ths thick faceplate.


----------



## sachu

simple and clean funch..this is your second EHHA eh..nice!


----------



## WyldRage

Hum... Seems I never posted mine, so here it is:


----------



## jdkJake

Nice build Funch, love the literal star ground, nice touch. What are you using as a power on circuit? That board looks interesting. Does it stage the power on (heaters followed by rails)? Is it multi-positional?


----------



## jdkJake

Nice build WyldRage. Did you put any panes in your "windows" or are they just open?


----------



## WyldRage

They have panes. I used front panel express for the EHHA's front panel. The original panel, which you can see on the first picture, did not have panes nor inscriptions. I drilled it myself, and the results were rather disappointing.


----------



## funch

Quote: 





jdkjake said:


> Nice build Funch, love the literal star ground, nice touch. What are you using as a power on circuit? That board looks interesting. Does it stage the power on (heaters followed by rails)? Is it multi-positional?


 

   
   Hey, Jake! Thanks. It's this:http://glass-ware.stores.yahoo.net/acswitch.html. Three position. I used one on my first EHHA build, and have installed one
  in my Bijou. Very nice switch. Quarter-inch shaft, BTW.


----------



## audionut

Gentlemen, Looks like the 1N5313 for CRD1 is no longer available through Mouser. The Mouser tech said the 1N5314 would probably work, but I wanted to see what you guys say and how critical that part is. The data sheet is here  http://www.centralsemi.com/PDFs/products/1N5283-5314.pdf   My boards are on the way and would greatly appreciate any input on whether the 1N5314 will work, or if anyone knows of a good sub for the 1N5313. Thanks!


----------



## jdkJake

Well, that is quite the pickle. I looked around a bit and that part is very much unavailable. Might want to contact the manufacturer to see what the issue is with availability.
   
  While the 5314 might work fine "as is", I suspect you would want experiment a bit and perhaps lower the values for R5 and R6 a bit (perhaps to around 43ohm or so?).
   
  I would prefer Alex to chime in and confirm any change. However, I suspect he is quite busy at the moment.
   
  Any other opinions/options?


----------



## audionut

Well I've since contacted Jeff at GJA, and he's using the J511's for CRD1 in his kits, and is considering offering them with the PC boards since the 1N5313's are so hard to source now. I ordered 2 of the J511's today from him today, and will start my build sometime next week. I had PM'd Alex on the 1N5314 for a possible sub, but he hasn't responded as of yet. I know he's extremly busy with his Liquid Fire, which is totally understandable.


----------



## gurubhai

Hi people, the recommended output mosfet IRF540/9540 have disappeared from the market around here. Retailers here are offering a IRF540N/IRF9540N as replacement.
  Is it ok to use them as a substitute ?


----------



## cfcubed

Maybe you'll get a more specific answer for this application but a quick search turned up these thoughts:
http://www.diyaudio.com/forums/car-audio/161985-irf540n-place-irf540-mtx-thunder-2300-a.html
http://www.diyaudio.com/forums/car-audio/186332-mtx-4202-irf540z-irf540n.html
  and you've probably seen 'em.


----------



## gurubhai

Yes,I have seen them. The N versions are supposed to be newer & better but some of the posts seem to suggest that they may not work well in some circuits. So, I was hoping for a more specific answer for ehha.


----------



## iamthecheese

I'm pretty set on the EHHA as my summer build, but I have a few questions.
   
  I'm planning on ordering one of the glass jar audio kits, and someone please correct me if I'm wrong but they are inclusive except for wiring, casework, and chassis jacks(aka the additional stuff i need to buy).
   
  I'm considering housing the transformers and power supplies in a separate box and stacking since on my desk I have more space vertically than horizontally, how much extra money would this design cost and is it even worth considering?
   
  I'm likely going to order this iron: http://circuitspecialists.com/prod.itml/icOid/9747 or similar for the project, to replace my basic weller I did my minimax build with.


----------



## funch

The kit comes with two boards, all components to populate them, and two transformers. You supply everything else.
  Be sure to inventory everything when it arrives and let Jeff know if there is anything missing.
   
  I have this station http://circuitspecialists.com/prod.itml/icOid/7307. It's not what you would call 'heavy duty', but
  works well and is cheap to replace. Easy for me too, as the shop is 40 minutes from my home. I'm not familiar
  with the one you linked, though. It seems to be a new line for CS.


----------



## jdkJake

Are you considering stacking the amp chassis on top of the transformer chassis? That would not be recommended due to the emission characteristics of a toroidal transformer. Not that people do not do it anyway....

Unless you are going to locate the transformers physically away from the amp, the stacking concept will actually have the potential to degrade overall performance.


----------



## iamthecheese

Quote: 





jdkjake said:


> Are you considering stacking the amp chassis on top of the transformer chassis? That would not be recommended due to the emission characteristics of a toroidal transformer. Not that people do not do it anyway....
> 
> Unless you are going to locate the transformers physically away from the amp, the stacking concept will actually have the potential to degrade overall performance.


 


  I was just thinking as a potential space saving design, but it it causes interference I can easily toss out the idea. I had just seen a ton of DIY amps with the PSU stacked underneath.


----------



## flynhawaiian

I've decided to undertake this project and had a few questions, and hoped some of you might steer me in the right direction.
   
  (1) I assume the BJT setup is better than the mosfet as far as sound goes?
  (2) If so which transistors might you recommend?  I have heard going with the Toshiba 2238/968 pair is the way to go.
  (3) If I use the pair, how is it wired?  Ie, Is the Q10BJT = 2238 and Q11BJT = 968
  (4) Which power supply should I use?  The board power supply or is there another recommendation such as the R-Core?
   
  Thanks Again


----------



## jdkJake

flynhawaiian said:


> I've decided to undertake this project and had a few questions, and hoped some of you might steer me in the right direction.
> 
> (1) I assume the BJT setup is better than the mosfet as far as sound goes?
> (2) If so which transistors might you recommend?  I have heard going with the Toshiba 2238/968 pair is the way to go.
> ...




1) Not necessarily. The MOSFET sounds mighty fine. I think only a couple of folks have built BJT versions (sachu and cobaltmute come to mind). I think sachu is in the position to directly compare the two versions, so, hopefully he will chime in.

2) There are multiple BJT's that can be used. The Toshiba's you mention are but one of them. Lot's of folks have opinions on the sound characteristics of the various devices available. So, it really comes down to sound preference. The build is actually designed for a different set of BJT's, so, be aware, the pin outs of the various devices may be different and needs to be accounted for appropriately.

3) Q10 is the NPN device and Q11 is the PNP device.

4) The Rev A includes a power supplies that are more than sufficient for both the amp and tube heaters. The rcore you mention is a transformer, not a power supply per se. You will need a set of transformers to feed both the amp and tube heater supplies. There are multiple ways you can go with regard to transformers. A search through the thread will yield many recommendations.


----------



## gurubhai

Quote: 





flynhawaiian said:


> I've decided to undertake this project and had a few questions, and hoped some of you might steer me in the right direction.
> 
> (1) I assume the BJT setup is better than the mosfet as far as sound goes?
> (2) If so which transistors might you recommend?  I have heard going with the Toshiba 2238/968 pair is the way to go.
> ...


 
  I used BJT(2238/968) for my EHHA  build & mosfets for rev.A, so I shall try to answer a couple of your questions.
   
  1) They are both excellent sounding & share the common EHHA sound sig.The differences are there, but are rather subtle.
  The mosfets are a little harder to find the sweet spot though since the bias setting varies quite a lot.
  The BJTs, otoh, are much easier to bias right.
   
  3)Like JdkJake said, check the npn/pnp status. One thing I must add that the pinouts of 2238/968 are inverted from those of stock BJTs. If you  use the rev. A board, you can simply use the mosfet holes for 2238/968s.


----------



## nullstring

I would also like to hear Sachu's opinion has he made the MOSFET's first and the BJT's second.
  I wonder if that changes anything.


----------



## iamthecheese

Does anyone have the dimensions of the Rev A boards? I can't seem to find them on the Cavalli website.


----------



## Sathimas

Boards are 107mm wide
   
  Heater supply is 20mm long
  Power supply is 44mm long
  Amp board is 83mm long
   
  Hope that helps


----------



## iamthecheese

Quote: 





sathimas said:


> Boards are 107mm wide
> 
> Heater supply is 20mm long
> Power supply is 44mm long
> ...


 
  Thank you very much, that it does.


----------



## flynhawaiian

I am about to order everything and am curious what other parts besides the ones listed in the BOM that I need to purchase.  Seems like there are a few things missing.  Thanks so much


----------



## jdkJake

Kind of an open-ended question as a lot will depend upon what you envision as the final product.

You will need a case, input/output jacks, a potentiometer, hookup wire, various screws and stand-offs, an IEC power input (preferably with a fuse), a power cord, possibly terminal strips of some kind for the star ground, possibly crimp-style, shielded spade lugs (highly recommended for the power input and chassis ground to earth ground connection) and the tools to put it all together. You might want to have the parts for a ground loop isolator in case you should need it.

Take a look at the various builds pictured in the thread and put together your list.


----------



## Cloud

Hi all, Will like to seek some opinions on wiring up my EHHA.
   
  Basically i am going for balanced set up. but i am going for "Dual Mono" balanced set up with 2 cases. 
   
  Each case will house 1 x Transformer, 2 X EHHA Rev A boards and 2 X E12 circuit. The idea is that if i need single ended output, I will just need to power on one case instead of 2. 
   
  I have attached a connection diagram and will like to seek help to check if everything is connected properly. I have omited the connections from transformer to boards as i dont think i will have trouble with that. 
   
  I will be using a single neutrik combo output jack for both XLR and 1/4" connections.


----------



## jdkJake

Don't forget the heater DC supply needs to be tied to star ground as well as the output ground of the main rail power supplies.

You may have to experiment a bit with the star ground point of the amp itself. In your drawing it appears you are attaching to star ground at the output point. You may find different (perhaps better) performance at the input point. You really have to try both and see which works better for you.

I trust you have seen this page:

http://www.cavalliaudio.com/diy/ehhaa/main.php?page=setup/setup


----------



## Cloud

Thanks jk,
   
  yup i have read a few times on the wiring page. will try a few configuration to see which works for me. 
   
  But in all the midst of excitement, i forgot to include my potentiometer. I guess 2 case balanced idea is hard to pull off.


----------



## jdkJake

Do you need a potentiometer? What will you be using for a source?


----------



## jdkJake

To complete the thought, you could always build a third box. The third box could provide either a passive or an active attenuation solution. Perhaps even include multiple input selection.

Something to consider.


----------



## Sathimas

I asked that some time ago already but got no real answer:
   
  If I reduce the bias current - could I build the ehha with just 1.5inch tall heatsinks?
   
  I don't know how hot they get, my case would have proper ventilation since the top
  is almost completely open - there'd be holes in the bottom too of course.


----------



## jdkJake

sathimas said:


> If I reduce the bias current - could I build the ehha with just 1.5inch tall heatsinks?




I suspect the 1.5" sinks would run fine without having to reduce the bias point. The MOSFETs run hot, but not overly so. I put some measurements up with the 2" sinks earlier in the thread. Search back for those to help guide your decision.

The key take away with using larger sinks is margin. There is much less to worry about from a thermal standpoint using the larger parts which have to work far less to dissipate the heat.

Be aware of one key point though, the size gain of the smaller sinks, if that is what you are seeking, may not be useable. Depending upon the tube socket you use, the height of the tube can be the driving factor in terms of overall height. Of course, if you are going for a through the case tube design, then this is not so much an issue.


----------



## Sathimas

Thanks for the fast replay!
   
  This is a quick shot of my current plan (design not final):
   

   
  I plan to mount the tubes off-board so that I can use the 50mm high frontplates from hifi2000.


----------



## Lil' Knight

^ Looks nice! But somehow I have a feeling that it'd be hard to roll the tubes with that way of mounting.

My friend is building his EHHA and having a problem. I haven't seen his build so this is just a vague description.
One board powered up just fine. The other one, when the amp section is disconnected, the PSU's readings were all fine. However, when he connected the PSU to the amp, the LM337 blew immediately. The heater is fine though.

Any idea regarding this problem?


----------



## Sathimas

Quote: 





> ^ Looks nice! But somehow I have a feeling that it'd be hard to roll the tubes with that way of mounting.


 
  Thanks!
   
  I quit tuberolling with my soha I - the differences where not big enough to convince me


----------



## jdkJake

lil' knight said:


> My friend is building his EHHA and having a problem. I haven't seen his build so this is just a vague description.
> One board powered up just fine. The other one, when the amp section is disconnected, the PSU's readings were all fine. However, when he connected the PSU to the amp, the LM337 blew immediately. The heater is fine though.




There is apparently a short somewhere on the amp board. Time to breakout a multimeter and the schematic and start the search.

If he posts some good pictures, the forum might be able to help isolate where the problem might be.


----------



## sachu

Quote: 





lil' knight said:


> ^ Looks nice! But somehow I have a feeling that it'd be hard to roll the tubes with that way of mounting.
> 
> My friend is building his EHHA and having a problem. I haven't seen his build so this is just a vague description.
> One board powered up just fine. The other one, when the amp section is disconnected, the PSU's readings were all fine. However, when he connected the PSU to the amp, the LM337 blew immediately. The heater is fine though.
> ...


 
   
   
  Obviously the PSU is being loaded severely. Check to make sure the negative rail is not shorted to ground on the amp section.
   
  check output MOSFET on the amp section. Check impedances between drain and gate.
   
  Also, get him to measure the trim pot setting on the amp board. Make sure it is turned counter clockwise (if its a 1k trimpot, it needs to be at 1k when measured across the outer terminals.)


----------



## jdkJake

sathimas said:


> This is a quick shot of my current plan (design not final)




Looks exquisite!

I look forward to your final implementation.


----------



## Lil' Knight

sachu said:


> Obviously the PSU is being loaded severely. Check to make sure the negative rail is not shorted to ground on the amp section.
> 
> check output MOSFET on the amp section. Check impedances between drain and gate.
> 
> Also, get him to measure the trim pot setting on the amp board. Make sure it is turned counter clockwise (if its a 1k trimpot, it needs to be at 1k when measured across the outer terminals.)




What I got from him were:
+ No short between the negative rails and gnd.
+ No short in the MOSFETs.

When the amp is up, he got +16vdc and -40vdc respectively. C4C blew too.


----------



## Sathimas

Hi there, since someone mentioned the bad term "tube rolling" some days ago
  it's constantly on my mind ... :-D
   
  I prefered the sound of a GE6680 in my SOHA - does anybody know that
  tube here and what tube could give a similar sound in the EHHA?


----------



## sachu

Quote: 





lil' knight said:


> What I got from him were:
> + No short between the negative rails and gnd.
> + No short in the MOSFETs.
> 
> When the amp is up, he got +16vdc and -40vdc respectively. C4C blew too.


 

 lol..i thought you said the negative rail was exhibiting problems. Looks like its the positive rail that is being loaded.
   
  Ask him to run the same checks as before. test for shorts between rail and ground. Then check transistors on positive rail, especially Q6 and Q8. RUn a diode check on those two.
   
  of course replace C4. Make sure its polarity is not switched around and that it is rated at 50V.
   

  
  Quote: 





sathimas said:


> Hi there, since someone mentioned the bad term "tube rolling" some days ago
> it's constantly on my mind ... :-D
> 
> I prefered the sound of a GE6680 in my SOHA - does anybody know that
> tube here and what tube could give a similar sound in the EHHA?


 

 Might be a tough task as tube rolling on the EHHA isn't as profound as it is on something like the SOHA or the CTH.


----------



## jdkJake

Assimilation is complete, resistance was futile.... 
	

	
	
		
		

		
			




   
  Okay bk_856er, okay sachu, I finally took the plunge to see what the fuss is all about. 
   
  These are Rev1's that I actually received way back in April. Finally got some quality time with them the last couple of days.
   
  Nice. VERY Nice.
   
  I now understand.


----------



## BK_856er

Congrats - it's a sweet pairing for sure!
   
  BK


----------



## foet

That looks awesome. Love the little windows .
   
  Having a slight trouble with my build again. At the last stage of soldering the actual amp boards and preparing for wiring.
  After missing some resistors (and having about 5 left who's values are nowhere mentioned in the BOM) - I'm missing components again: Q6, Q7 and CRD1. Are any of these optional maybe? Or did I receive a slightly messed up kit from GJA.
   
  Also.. I just figured out I wired P1 wrong looking at people's complete builds. Does the direction matter at all or is it time to pull it and reverse it .


----------



## jdkJake

Thanks.
   
  Regarding your build, no those are certainly not optional components. The CRD biases the tubes and Q6/Q7 are at the heart of the VAS section of the amp. So, I would carefully check again.
   
  What "leftover" resistors do you have left? Also, which ones did you consider missing?
   
  The P1 orientation should be okay, just be aware it will not respond in the manner you would expect.


----------



## foet

I was missing the R1 1MΩ, R30, R31 200kΩ and the R17 (mosfet) 1.5KΩ. I ordered those along with some items I still needed from mouser so it really didn't bother me. I rather bought them and was sure then solder the only ones remaining because they were the only choices left.
   
  "pulls out good oldie multi"
   
  At the moment I only have the following items left from my kit : the ALPS, the 2 sockets for the tube's, 4 LEDS, the 2 opamps and the resistors. 410K, 120K, 2* 130K, 145K and a 222K Ω.
  Also 2 items I cannot identify, they look like the 3 legged transistors only with 2 legs (middle cut away) and the following text on them ; 511 <triangle sign> C513AB and a (P) stamped on the back. Could these be an alternative for the 1N5313 CDR1? 
	

	
	
		
		

		
		
	


	



   
  As said, all other boards are complete at this point with everything soldered. Since the components for the 2 other boards were in separate labeled bags it made things a bit easier to sort out. I matched (and measured as far as possible) everything soldered so far so I find it strange to have non matching combinations left (i.e. no pairs of resistors but mostly single values).
   
  Off course when everything says "Boom" on first power up I'll know I was in error


----------



## jdkJake

Yes, the J511 is a replacement for the 5313 CRD. See back a few pages ~post 1291.

What are the LED's rated?


----------



## Navyblue

Guys I have a question.
   
  I am looking for a tube/hybrid preamp (primarily) that will also drive headphones (as a bonus). So transparency and details are most important, and driving power is less so. Which of the EHHA, SOHA II and Bijou would be best for my need? This is subjective but I'd like to hear your personal opinion.
   
  Thanks.


----------



## foet

Thanks for the help jdkJake.
   
  Okay, how would I align this thing (J511)? There is no indication of poles or direction and Google doesn't directly assist me.
  No idea what the led's are rated, my multi doesn't have that option. I can tell you they are blue (at least 3 are - 1 doesn't light up when using diode check). :<

  
  Quote: 





jdkjake said:


> Yes, the J511 is a replacement for the 5313 CRD. See back a few pages ~post 1291.
> 
> What are the LED's rated?


----------



## iamthecheese

I have my glassjar kit and a 12x12x3 par metal with extra vent holes coming soon, I have a couple questions about grounding though. I've seen a couple people use a ground loop isolator, is my understanding correct that this gets connected to the ground from the AC socket, and this isolator keeps that ground separate from the star ground? If so, what would be a good isolator to use?


----------



## BK_856er

Quote: 





iamthecheese said:


> I have my glassjar kit and a 12x12x3 par metal with extra vent holes coming soon, I have a couple questions about grounding though. I've seen a couple people use a ground loop isolator, is my understanding correct that this gets connected to the ground from the AC socket, and this isolator keeps that ground separate from the star ground? If so, what would be a good isolator to use?


 

 Nope - typical ground loop breaker goes between star ground and chassis.  AC socket safety ground to chassis is separate/short/not shared with anything else.  I don't know if it's important, but I also took some time to remove internal black anodizing on the par-metal case to get good conductivity between all the panels.
   
  BK


----------



## iamthecheese

Quote: 





bk_856er said:


> Nope - typical ground loop breaker goes between star ground and chassis.  AC socket safety ground to chassis is separate/short/not shared with anything else.  I don't know if it's important, but I also took some time to remove internal black anodizing on the par-metal case to get good conductivity between all the panels.
> 
> BK


 
  Ah, thanks for the clarification...any suggestions for a ground loop breaker?


----------



## sachu

Class X or Class Y 250VAC rated 0.1uF capacitor and a 10R/5W wire wound resistor in parallel.


----------



## jdkJake

Quote: 





foet said:


> Thanks for the help jdkJake.
> 
> Okay, how would I align this thing (J511)? There is no indication of poles or direction and Google doesn't directly assist me.
> No idea what the led's are rated, my multi doesn't have that option. I can tell you they are blue (at least 3 are - 1 doesn't light up when using diode check). :<


 


  I am assuming you have the linear systems part. Can you verify this is indeed true?
   
     http://www.linearsystems.com/datasheets/J500.pdf
   
  As for the LED's, it would be nice to know the voltage and operating current in order to determine the correct resistors to use at R32, R33, R5R, R6R and R3H. What did you install at those locations?


----------



## foet

Yes, looks like thats it. So, when facing the round side to me, the right pin should be near the marking (litle arrow)?
   
  For the resistors, I followed the BOM. I've quickly checked the coloring on R32 and R33 to be sure :
  R32 / R33 : 2.94K
  R5 / R6 : 47
  R3 : 1K
   
  Just ordered Q7 and Q6, 1.5 euro for 50 of each.. I'll have some spares .


----------



## jdkJake

So pin 1 is the anode and pin 2 is the cathode. 
   
  Using the nicely placed diode reference on the silkscreen of the board, make it match the diagram.
   

   

   
   
  As for your resistors. The value for R32 and R33 is completely dependent upon the LED's you are using. We really need to know the characteristics of the LED's you have to know if those are the correct values to use.
   
  For R5 and R6, what value was originally shipped to use with the J511? The values of R5 and R6 are used to correctly set the bias of the tube. The maximum forward current for the J511 is greater than the maximum forward current of the 1N5313. So, while probably close enough, you might want to finesse this value to get it to match what Alex intended with the original CRC design.
   
   
  R3 should match R4 and be the value as specified in the BOM (1k)


----------



## Vaughn

Hey guys,
   
  I've been poking around trying to find a nice amp that plays well with vintage orthos as well as HD650's. The EHHA has caught my interest but I'm concerned that I might need to have different gains for these two types of headphones.
   
  Any input? Also, is it fairly easy to switch gain (I.E. could I do it with a switch mounted on the front panel)?


----------



## WyldRage

Quote: 





vaughn said:


> Hey guys,
> 
> I've been poking around trying to find a nice amp that plays well with vintage orthos as well as HD650's. The EHHA has caught my interest but I'm concerned that I might need to have different gains for these two types of headphones.
> 
> Any input? Also, is it fairly easy to switch gain (I.E. could I do it with a switch mounted on the front panel)?


 

 The EHHA plays well with my both my orthos and Grado.
   
  As for switching gain, that's what the volume control is there for. 
	

	
	
		
		

		
			





 Seriously, I have had not trouble setting the right volume.


----------



## jdkJake

vaughn said:


> Hey guys,
> 
> I've been poking around trying to find a nice amp that plays well with vintage orthos as well as HD650's. The EHHA has caught my interest but I'm concerned that I might need to have different gains for these two types of headphones.
> 
> Any input? Also, is it fairly easy to switch gain (I.E. could I do it with a switch mounted on the front panel)?




The default gain as recommended in the BOM is 9. That is more than plenty for most sources including the HD650s. I am currently running a gain of ~6.4 and have more than enough headroom for my HD605's and LCD2 orthos. What are the electrical and response characteristics of your orthos?

You could make switchable gain a number of ways. I socketed the four resistors involved in the setting of the gain (2 per channel). You could make those values switchable on demand, but, I am not sure the wiring challenge in doing so (along with the potential for inducing noise) would be worth it. Hard to say. 

Willing to break new ground?


----------



## Vaughn

Right now I'm using an Audio GD-NFB 12 and it sounds best on the high gain setting with both the HD650's and the Fostex T20 V2's as well as modified T50rp's. I guess I am worrying too much about it...
   
  I don't really want to break new ground, btw
	

	
	
		
		

		
		
	


	




 I'd rather leave that to someone else... 
   
  I'm just trying to find something that will work will with both types that will be a definite upgrade from the amp in the NFB-12, which actually sounds pretty decent.


----------



## jdkJake

I think you will find the EHHA has more than enough gain for those phones. Some might even say too much with the default build of 9, however, that is highly dependent upon source and preferred listening level. If you build it and socket R11, R13 and R14 on each of the amp boards, you can always tweak until your hearts content.
   
  Not sure how it compares to an NFB-12 as I have never heard one. But, I know the EHHA sounds mighty fine to these ears. Trying out a set of 6N27P tubes as I write this.


----------



## Vaughn

Thanks for the advice...I would be using the DAC in the Audio GD if I went in this direction.


----------



## stringgz301

Quote: 





jdkjake said:


> I think you will find the EHHA has more than enough gain for those phones. Some might even say too much with the default build of 9, however, that is highly dependent upon source and preferred listening level. If you build it and socket R11, R13 and R14 on each of the amp boards, you can always tweak until your hearts content.
> 
> Not sure how it compares to an NFB-12 as I have never heard one. But, I know the EHHA sounds mighty fine to these ears. Trying out a set of 6N27P tubes as I write this.


 


  So what's your review of the 6N27P?


----------



## jdkJake

stringgz301 said:


> So what's your review of the 6N27P?




Well, I have only had a couple of weeks with them, the first few days of which were mostly letting them wake up from their extended slumber, so my impressions are still pretty preliminary. So far, I like them a lot. They have a very clean, detailed and extended sound. The highs are crisp, the bass is deep, tight and very much in control. The mids are smooth and full, but leaning away from lush.

I like the sound a lot with the HF-2, as I expected after your comments. The HD650 surprised me a bit. I really like what they did with these phones, particularly the low end which really focused up more than I expected. A very nice sound. With the LCD2, things get a bit different. The LCD2 sound is still new to me, so, I really should not be rolling tubes through it right now, but, life is short.   I am somewhat on the fence with these on the LCD2. I love the low end control and high end extension, but, the Telefunkens really bring out the lush creamy mids the LCD2 is capable of reproducing. The trade-off then becomes a bit less extension and slightly looser bass. The Tele's also have the edge in soundstage and presence as well.

So, at this point in time, I really like the 6N27P. Price and availability is also a big plus. In the end, I suspect the mu (amplification factor) of the 6N27P is higher than the Telefunken, which results in higher OL gain and a corresponding higher NFB. Back during my CL/OL/NFB experiments, I was able to take an individual set of tubes through a similar set of sound profiles by manipulating the NFB. I wonder if the NFB was brought down on the 6N27P by a few db and up on the Telefunkens by a few db, how close they would start to become. I suspect the Tele would still retain a more refined sound with the 6N27P being the more analytical of the two, but, it might be an interesting experiment.


----------



## iamthecheese

What size standoffs does everyone recommend? I have a 3" tall par metal enclosure, and the glassjar kit. I was thinking 1/2 in for better airflow than 1/4 inchers, but will that fit in a 3" tall case with the heatsinks and tubes?


----------



## minez

Hi,

Do I need to unplug the headphone before powering up?
I always unplug the can before turn on the amp, but last time I turn the amp on without unplugging the can and my can blown up.

Thank you


----------



## sachu

yes, if you have no DC protection circuitry in your amp, you ALWAYS NEED to unplug your headphones during power up and power down.
   
  Also you need to make sure you turn the volume all the way down before changing headphones. 
   
  Sucks about your headphones getting fried.


----------



## minez

Thanks sachu


----------



## minez

sachu, do we need to unplug the headphones before turning on or off for all kind of headphone amps? Or most of headphones amp got dc offset protection circuit? Thanks.


----------



## sachu

I do it for any and all amplifiers.


----------



## minez

Thanks sachu


----------



## cfcubed

minez - Pick "Search This Thread" and search for e12 for info on this in context of this amp.
   
  Seems most amps w/tubes in them could use at least a pwr on delay/pwr off output relay latch circuit if not more advanced offset protection.  Seems most DIY amps do not incorp them by default in favor of leaving it to the builder's option (to add something like amb e12, or as simple as 555 delay relay for example).
  The potential for DC offset esp. during pwr up / pwr down cycles is known to the DIY community (builders) based on the device's design.  If you bought & did not build the amp the seller should've made you aware of this.  
  In any event, many users do choose to manually disconnect / re-connect headphones at pwr on / pwr off even for amps with delay/protection features or even for amps with little or no DC offset potential.


----------



## funch

Quote: 





iamthecheese said:


> What size standoffs does everyone recommend? I have a 3" tall par metal enclosure, and the glassjar kit. I was thinking 1/2 in for better airflow than 1/4 inchers, but will that fit in a 3" tall case with the heatsinks and tubes?


 

 Quarter inch should be fine.


----------



## jdkJake

iamthecheese said:


> What size standoffs does everyone recommend? I have a 3" tall par metal enclosure, and the glassjar kit. I was thinking 1/2 in for better airflow than 1/4 inchers, but will that fit in a 3" tall case with the heatsinks and tubes?




Not sure you can make the 1/2 in work. It is pretty tight. Better safe with the 1/4 in.


----------



## iamthecheese

I'll go with the 1/4 inchers just to be safe, thanks guys!


----------



## iamthecheese

Well my amp is mostly done, but full of all sorts of problems.
   
  The tube heater circuit outputs correctly, and the tubes heat. The PSU outputs around +-27V. When I power the amp up dc offset jumps too 3.6V, and settles to around 3.0V. When I initially checked the bias, it read at 60 mv, and as I started turning the trimpot it spiked to between 18-19V, went back down to around 1.5V. Then I freaked out and turned it off. I have a 2 stage power switch and I let the tubes heat for about a minute before powering on the main rail. Turned it on again and reading was back around 100 mv, the heatsinks on the amp part are barely getting warm though, not as much as I would expect...


----------



## jdkJake

So, did you follow the initial setup sequence exactly and verify each stage of the build?
   
     http://www.cavalliaudio.com/diy/ehhaa/main.php?page=setup/setup
   
  How are you measuring DC offset?
   
  Pictures would help as well.


----------



## jdkJake

Also, check and verify the orientation of the DC servo opamp (IC1). Make sure pin1 of the device is oriented properly.


----------



## iamthecheese

I'll get some pictures tomorrow, but I am following the Cavalli instructions
  I pretty much get to this part(Rail supply reads around 27 VDC, tube heater output is 6.30VDC) :
 Amp Power Up  Look for smoke. If there is none, proceed.
_*Wait for the output DC to settle into the low mV range. If this does not happen the servo is not working. Stop and turn off the power.*_
   
  I measured it from the out terminal to the group terminal on the amp board.
  The op amp was warm, but not like burning hot or anything.
  I'll try to get a hi-res picture with a dslr tomorrow.
   
  Its actually only 1 board, since I'm waiting on some parts for the other one.


----------



## sinae

If i buy the EHHA revA kit and follow all instruction to the letter. I wonder if I can do that in my first diy but its an interesting challenge.. I would sure learn a lot 
   
  iamthecheese did you find a way to fix your problem?
   
  From the pictures I saw of your diy project i'm wondering if it would be easy to create an external power supply with that transformer..
  So the amp would be in two pieces.. What your opinions on this?
   
  I find those diy boxes a little too big for me.


----------



## iamthecheese

I haven't had a chance to look at it yet, I've been packing to go move back for college.
   
  I wouldn't really recommend this for a first project, I started with a minimax kit(great for first ambitious DIY'ers), then did an opus dac, then this.


----------



## sinae

cool thx for your reply. Im gonna think about this then


----------



## jdkJake

Quote: 





iamthecheese said:


> I measured it from the out terminal to the group terminal on the amp board.


 

 What do you mean when you say group terminal?
   

   
  You can measure DX offset across O2 and O3 of the terminal block where power enters the amp and output exits. What is the measurement at that point?


----------



## iamthecheese

Quote: 





jdkjake said:


> What do you mean when you say group terminal?
> 
> 
> 
> You can measure DX offset across O2 and O3 of the terminal block where power enters the amp and output exits. What is the measurement at that point?


 

 That's where I measured from. It was the voltages I said above, around 3.5ish.


----------



## jdkJake

Do you have an auto ranging multimeter? If not, what range was it set at?

Just trying to establish a baseline and ask the obvious questions first.

Did you verify the correct orientation of the DC servo opamp?


----------



## jdkJake

Also, since you are testing a single board, how are you establishing a ground reference? Particularly signal ground.


----------



## iamthecheese

I'm off at college now...couldn't bring the amp along 
	

	
	
		
		

		
			





. I will be back for labor day weekend, but I've had to put the project on hold until then. Thank you so much for your help so far, it means alot of have some sort of support line.


----------



## jdkJake

No problem. Study hard.


----------



## iamthecheese

I gotta find a multimeter since I conviently left mine back at school...but as for IC1, it is currently oriented(Tube is bottom center for reference), with the dot on the op amp in the lower right.


----------



## jdkJake

Quote: 





iamthecheese said:


> I gotta find a multimeter since I conviently left mine back at school...but as for IC1, it is currently oriented(Tube is bottom center for reference), with the dot on the op amp in the lower right.


 


  Okay, that is the correct orientation.
   
  Most importantly, how are you establishing ground in your test setup? How do you have the board wired up in your test setup? A pic or two would help as well.


----------



## iamthecheese

I just installed the 2 missing components on the second board, after I wire everything up completely I'll take a couple pictures.


----------



## iamthecheese

Well partway through the wiring I decided to fire it up for kick and giggles.
   
  I have a 2 stage power switch installed, so I let the tubes heat for a minute or two before turning the amp on. When I turned the switch to both on, the board I just finished light up, at that point I remember I installed LEDs under the tubes.
   
  So a new symptom to add to the list is LED under board not lighting for the problem board.
   
  Then I broke out my dads DMM, and the VDC between out and ground on the second boards terminal block(the one with working led under the tube) was around 2 mV and still dropping.
  So then I measure LED+ to LED- just for fun, on the working board it measures 2.8V, on the problem board it measure around 0.7V.
   
  Pic to come, I promise. Just gotta find the cable to hookup the camera.
   
  By the time I finished typing this, I checked dc offset again, and it had dropped to .5 mV.


----------



## iamthecheese

Sorry for the poor quality...phone camera.


----------



## jdkJake

On the problem board, with the amp hooked up to the power supply (and powered on), are you still reading ~+/-30VDC?


----------



## jdkJake

While you are measuring, also measure from +LED to ground and -LED to ground. The goal is to see which of the rails is being pulled down and then find out where (or which part or solder bridge) is doing the pulling.

No offense, but, that picture is worthless. I swear, a decent point and shoot should be standard issue for these projects. Sometimes they are as equally valuable as a decent iron.


----------



## iamthecheese

Alright, found a better camera.

   
  Voltage on the problem board for the LED, from LED- to G measures about -200 mV, and LED+ to ground measures about 250 mV.
   
  Voltage coming off PSU is +27 and -27


----------



## jdkJake

Okay, that is much better. How about a couple of close-ups of the problem board? Which is it BTW (in the picture shown)?
   
  Also, verify the orientation and correctness of V- and V+ (79L15 and 78L15). Make sure they are not accidentally swapped.


----------



## jdkJake

BTW, you should tie your AC ground directly to the chassis first prior to attempting to use the ground loop breaker.
   
  Scrap off a bit of the anodizing and attach using lock washers to ensure you get good contact with the bare metal. Once you have established a good connection between AC ground and the chassis, you can then use the ground loop breaker (if required) between signal ground and chassis ground. I generally make the AC ground connection a short segment of solid, lower gauge wire as close to the AC inlet as workable.
   

   
  This will make the build safer.


----------



## iamthecheese

V- and V+ appear to be correct, here is a close up of the problem board(the one closest to the AC inlet in the big picture):
   
  Also, I'll work on changing that ground wiring around, thanks for the tip!


----------



## jdkJake

How about a shot of the underside if you can?

Also verify the MOSFETs (q10 and q11) are correct as well.


----------



## iamthecheese

I can't seem to get a decent picture of the underside...but heres my attempt:

  The flash would either reflect too much off of the pcb, or it would end up too dark with no flash, so my apologies in advance about the picture quality.
   
  The MOSFETs are correct, as well as the resistors(atleast they appear to be). I did a quick cross check between both PCBs(learned my lesson after my first DIY to put the resistor values up).


----------



## jdkJake

So,the best way to take a picture like that is to use no flash and indirect lighting. A bright room or even outside can help, but, dump light on the board and avoid the flash.
   
  In any case, we need to verify you are getting voltage from the PS to the amp board.
   
  We can use the BJT pads (opposite the MOSFETs) to measure the voltage going into each MOSFET drain. On each side, by the test points (TP1 and TP2) there is a set of pads. Measure between the middle pad and ground on each side of the board (each MOSFET).


----------



## iamthecheese

Sorry for the delay, school arose as a delay again.
   
  Q11B(Ground was placed on pad 2)
  pad 2 to pad 3 = 18.0 V
  pad 2 to pad 1 = 20.6 V
   
  Q10B(Ground was placed on pad 2)
  pad 2 to pad 3 = -16.5 V
  pad 2 to pad 1 = -19.7 V
   
  Those measurements are from the problem board, I can measure the good board if needed.


----------



## iamthecheese

Sort of a strange update, I actually reflowed a bunch of joints on the problem board before I left to go back to school. After I measured those voltages last night, I figured I might as well check the DC offset. Well, to my surprise it had actually dropped to 0 mV, as same as the good board was reading. So then next I measured between OUT and TP1, and was able to bias both boards. So after checking voltages no less than 3 times each, everything appeared normal. So I plugged a cheapo gaming headset I got ages ago, and I got sound from both channels, but from the right channel(problem board) there was a pretty decent hum, left board was dead silent until I opened the volume up all the way(with nothing plugged in of course). The LED under the problem board for the tube still doesnt light though.


----------



## sachu

Might have the LED on backwards.
   
  What sort of a noise are you getting fromt he bad chanel? is it a hiss or a humm (like a ground humm)
   
  Do you have a star ground in place?


----------



## iamthecheese

I'd say more of a hum for sure. I have the star ground setup with all the wires connected to a terminal block. I tried both wiring options from the cavalli website, and still got hum.


----------



## jdkJake

Well, that was not exactly what I was asking you to measure, but, I guess that is OBE. I was looking for a measure from ground to pad2. Not between pads.

Anyway, I would first check to make sure you have all the wires seated correctly in the terminal blocks. Sometimes they can be tricky. Especially is a piece of insulation or such prevents a good contact. 

Some quick and easy things to try first are to swap the tubes across both boards. I would do the same for the signal input wires. Swap the signal input between the boards and see if the hum follows with the swap or remains with the suspect board. Unless you have already tested it, there could be an issue with your glassware attenuator solution. 

Swapping outputs is also something to try and see if the problem follows with the swap or remains with the suspect board.

After that, then you may still have some suspect soldier joints.


----------



## iamthecheese

I messed with the wiring some with some interesting results. Before I messed with the wiring, I hooked the amps output up to a mixer I have just for fun. The hum was lighting up the -24 dB light on the mixer on the right channel, also when I turned the amp on and off, the left channel would remain silent, but the right channel would shoot up to the +6 dB, and start to light up the clip light before it went down. Switching the tubes didn't change anything. I took the input wiring and tightend up the connections and fired the amp back up. The hum had dropped off the the dB meter LEDs. So I switched the amp on and off a couple times, and got a -12 dB spike max, instead of a clip. I decided to try plugging in some headphones next, and the hum was still there. It had dropped off greatly on the right channel(problem board), but had increased slightly on the good board(left channel). Another curious thing, is if 1 RCA is plugged in(doesn't matter which channel, or what the RCA is coming from, as long as it is plugged in) the hum is there, but if I take both RCAs out, the hum drops to almost inaudible levels.
   
  Tl;dr: Hum seems to be a ground problem.
   
  I think my terminal block may not be the best solution for the star ground, is the best way to do a start ground a single post and some crimp connectors?
   
  edit: If it makes a difference, all of my signal wires are shielded.


----------



## jdkJake

Sounds like a classic ground loop. Are your RCA jacks isolated from the chassis? If not, they should be.

The terminal blocks should work just fine. That is what I am using and my amp is dead quiet. How are you using the shield on your shielded wires? From the last picture I saw, it appears the shields are floating. I may be wrong. Shieds are most likely not the issue in this case. You have a ground loop that needs to be cured,

How have you wired up your attenuator? How is ground being passed through it? Is the attenuator board isolated from the chassis? Is it tied into a ground at some point? I suspect the issue lies somewhere on your ground passing through the attenuator. Diagram up how you wired in the attenuator. I think it will be most telling.


BTW, did you tin your wires that go into the terminal blocks? If so, did you clean the flux off them prior to inserting them? Also be careful with too much torque on the terminal blocks. You can literally sever the wire such that you no longer have contact. I would reseat all of the wires going into your input terminal block connections. Pull out the wires out, check for damage, clean them if required and reset them into the block and torque down to the point of being snug, but not brutally tight.


----------



## iamthecheese

I didn't tin any of the leads, except the signal output wires. I did remember to clean them though(It was only 2 wires).
   
  The jacks should be insulted, they are the neutrik D series jacks: http://www.parts-express.com/pe/showdetl.cfm?Partnumber=092-232
   
  The shields are just floating, I just stripped the shield and jacket off where I needed, and just used the black wire for ground, and white for signal. (It was a twisted pair wire, 24 awg, SPC).
   
  When I get a chance tomorrow, I'll re-seat all the wiring and hopefully that should cure the ground loop.


----------



## jdkJake

Perhaps, but still a worthy endeavor even if it is unlikely to cure the problem. If you are using stranded hook up wire, you should really consider lightly tinning the wires, especially those that go into the terminal blocks. Those screws can be very hard on untinned stranded wire of that small a gauge. A lot of times, a number of the strands will spread and break right off by the screw action alone. The tinning makes them act a bit more like a solid wire at the connection point and is far, far more mechanically robust.

Did you ever fix your ground loop isolation scheme? As it stands now, I am not sure if you have a separate signal ground vice chassis ground. Hence the ground loop. While you are in there, with the power off, use you multimeter and measure the resistance from the star ground to a clear part of the chassis. By clear, I mean an area without anodizing. The anodizing acts as an insulator, so, you need a clear shot to the bare aluminum. Since it does not appear you have drilled into the case yet, sometimes the pem nuts on the bottom plate act as a decent place to measure. Otherwise, if you have attached your safety ground to the case as described previously, that will work perfectly. You want to see if the connection between signal ground and chassis ground is open, shorted or at some resistance in between. Ideally, if the ground loop breaker is installed, the resistance should measure the value of the resistor used for the isolator.

Also, details on how you wired through the attenuator would still be very helpful.


BTW, floating shields do not really act as shields without being tied to a ground source.


----------



## iamthecheese

I haven't had time to change around any wiring yet(being an engineering student kinda sucks sometimes...), but I did have time to sketch up how the volume control is wired in.
  Circles are RCA jacks.


----------



## jdkJake

Okay. With a diagram like that, you really must be busy.  
	

	
	
		
		

		
			




   
   
  So, are you using the glassware A3?
   
  The goal of the exercise is to ensure the ground is correctly routed through the attenuator circuit. You should be able to buzz out the continuity from the jacks into the inputs of the amp boards for both the signal as well as the ground wires. Be sure nothing is plugged into the rca jacks when you make this measurement.
   
  Are the switches isolated from the chassis front panel? In this case, you do not want them to be isolated. They should be directly attached to the chassis front panel (attached to chassis ground).
   
  Additionally, measure to be sure the front panel and bottom panel are electrically connected (you should be able to measure a direct short between the front panel and bottom panel). Sometimes, due to paint or anodizing, the front panel can float from the rest of the chassis. This happened with my panel (too much paint) and I had to wire my pot body directly to a chassis ground point on the bottom plate.


----------



## Cloud

Finished up my EHHA Rev A along with some modifications which yields great results. 

   

  1) If you prefer punchier, deeper bass and a more full bodied sound, consider swapping the 2200uF caps in the power supply to 4700uF. I uses a pair of Rifa 4700uF 63V on each power supply to excellent results. Terrific sound on my LCD-2

   

  2)I use AMRG(Amtrans) 300ohms resistor for R2(plate loading resistor) as advised by a DIY shop dealing with tubes. More transparent, wider soundstage and silkier highs! 

   

  These are the 2 mods i tired and really like the effect, especially the caps mod. Try it folks!

   

  I will post up some pictures this weekend.


----------



## iamthecheese

Quote: 





jdkjake said:


> Okay. With a diagram like that, you really must be busy.
> 
> 
> 
> ...


 

 It is the A3, the metal housing of the switches is right against the front panel. I'll check resistances over the weekend, my weeks have become consumed by school work.


----------



## capernicus

can anyone tell me the dimensions of the Rev A PWBs?  I'm getting ready to make my order and am starting to think about enclosure options...
   
  Any case recommendations?


----------



## funch

The Par-Metal case with a 12 x 12 footprint, 3 or 4 inches tall is popular. I used a 3" tall one myself and was very pleased.


----------



## wdahm519

Any hope that I could crap the EHHA Rev A into a case sized 11.928 x 7.93 x 2.93.  It'll be about 4 inches shorter in the back than a 12 x 12.  I just really want to use this enclosure, badly:
   
  http://www.mouser.com/ProductDetail/Hammond-Manufacturing/1441-24BK3CWW/?qs=sGAEpiMZZMsrGrAVj6eTvQj%2fOYSSS1QrYDN8rBC3RLk%3d


----------



## sachu

Might be possible. YOu will probably have to mount the transformers on the outside/ on top of the case however.


----------



## wdahm519

Hmm, that might kind of kill the look.  I may have to go with the 16.8" x 9.5" or however large that one is.  Eh, maybe its just worth going with a Par-Metal case in the end.  I guess I can figure out minimum dimensions after I build the boards.
   
  Thanks for your input.


----------



## cfcubed

>  will probably have to mount the transformers on the outside/ on top of the case however.
   
  Or in a separate enclosure where they belong    How's that for opinion  
  I've come around to trying to make all my builds 2-case builds now, having experimented w/transformers - input stage distances WRT hum.  No ground-loop breaker to fit in either.
   
  Going that route w/my budgety compact EHHA I:


----------



## wdahm519

I don't know. Everpne always whines about hum but my big hammond transformer is inside my Bijou case and its dead silent...


----------



## cfcubed

So now I'm whining about you whining about others whining about hum 
  Anyway there a lot of variables WRT hum & its my opinion that its nice to eliminate one of them.  Builders choice.


----------



## capernicus

As I start to embark down the EHHA build path I am interested if anyone has listened to the EHHA with some Denon D2000s?  I'm considering them as an upgrade to my SR60s / SOHAII Rig.  Any thoughts on this one? or can anyone possibly suggest a better pairing in the price range? I have a broad taste in music - everything from Reggae artists to Dave Matthews and Sarah Mclachlin to heavy hitting rock like Breaking Benjamin type stuff...  Not much classical or Jazz to be honest.  Looking to keep the price down in the sub $300 range... (found Denons for $250!)  Thanks!


----------



## hahihuheho

Guys..i've searched the thread and couldnt find it.. could anyone clarify what's the power output of this amp at 50ohms??


----------



## glenda

I couldn't find the info on the site.  What is the gain?   What is the Vrms out before clipping?


----------



## jdkJake

The default gain is ~9, but, can be changed. Either at initial build time or by socking a few resistors, changed with minimal effort as desired.
   
  Power output is dependent upon the chosen output devices (MOSFET or BJT).


----------



## glenda

Quote: 





jdkjake said:


> The default gain is ~9, but, can be changed. Either at initial build time or by socking a few resistors, changed with minimal effort as desired.
> 
> Power output is dependent upon the chosen output devices (MOSFET or BJT).


 

   
  Power is not a concern only need 200 mW,   but voltage swing is a challenge for most headphone amps with inefficient 600 ohm phones.  
   
  The Betta 22 would definately get the job done (specs are well documented) and a 2 channel build from GJA isn't much more than the EHHA kit,  read thru this thread and there wasn't much technical info on the design capability).  How close can the output swing to the rails before clipping ?


----------



## jdkJake

I would check the main EHHA thread as I am sure it has been discussed.
   
  http://www.head-fi.org/t/422429/cavalli-ehha-embedded-hybrid-headphone-amp
   
  The revA, for all intents and purposes, performs identically to the original version. At least in terms of output power.


----------



## redwarrior191

hey..i'm also interested in it.. i've searched both threads and couldn't find any info about the output power.. anyone has any info about this??


----------



## jdkJake

Quote: 





redwarrior191 said:


> hey..i'm also interested in it.. i've searched both threads and couldn't find any info about the output power.. anyone has any info about this??


 
   
  Quote: 





glenda said:


> Power is not a concern only need 200 mW,   but voltage swing is a challenge for most headphone amps with inefficient 600 ohm phones.
> 
> The Betta 22 would definately get the job done (specs are well documented) and a 2 channel build from GJA isn't much more than the EHHA kit,  read thru this thread and there wasn't much technical info on the design capability).  How close can the output swing to the rails before clipping ?


 
   
  Start here:
   
  http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1155#post_7238319
   
  There are other snippets buried in the thread. Search is your friend.


----------



## glenda

Thanks,  I found in that thread the output can swing well over 12Vrms before clipping which is great for my needs.
   
  Now one other issue that I didn't find info on is the noise floor.  It looks like he rev a has inegrated DC heat which took care of some of the earlier noise issues,   but the noise floor on the scope shots on the EHHA website  look relatively poor. 
   
  With the EHHA and  Grados or similiar high efficient low ohm headphones is there a "black" background?   On ecpaudio's's website Satvisky says one of the most important measures of a headamp is to hear nothing,  no static, hum, buzz, etc with grados playing a silence wav.   Has anyone tried this with their Rev A?    
   
  One other curiousity question is why wouldn't you paralell two of the CRD's at the cathode of the input tube,  I mean a simple glance at the tube's datasheet shows this would put one in a much more linear region of the curve,  or is it that the NFB makes this a non-issue?  I am surprised no one has tried this, so I must be missing something?
  
  thanks for the help,  I hope there are still others building/tweaking this innovative design and I am not needlessly bumping an old thread.


----------



## jdkJake

I am sure there are plenty of folks building the design, not so sure about tweaking it. Regardless, this thread has been pretty quiet as of late. Looking back, the Rev A is a little over a year old, certainly not ancient, but, obviously not FOTM any more. 
   
  As for the noise measure, I have not seen anyone post any measures of the rev A. Personally, I have not objectively measured it, but, subjectively, it seems quite black to me. As of late, that can be a dangerous statement, but, my measurement tools are fairly primitive and would probably mislead rather than inform. I may try to change that situation, just not high on the priority list as of late.
   
  That said, I think the noise floor is going to be impacted by the build techniques (power supply locations) as well as the overall gain setting of the amp and the source being employed. The nice thing about the rev a is the power supplies can be detached for a two case build if so desired.
   
  I have Grados, so, if you can provide a silent waveform (which I assume is created to be a binary zero representation of silence), I will be more than happy to give it a subjective listen. 
	

	
	
		
		

		
		
	


	



  ​
  As for the cathode bias point, I am not sure why Alex picked what he picked, but, I am sure there was rationale behind the choice. I think it would be most cool if you experimented a bit in that area and shared your results.


----------



## FOXY

What are the differences between the EHHA and BETA22 in terms of sound?


----------



## Beefy

Depends what tubes you put in the B22


----------



## UKToecutter

That's sooooo... funny.


----------



## stixx

Quote: 





> Regardless, this thread has been pretty quiet as of late. Looking back, the Rev A is a little over a year old, certainly not ancient, but, obviously not FOTM any more.


 
  Hang on in guys...mine is still in the works. 
	

	
	
		
		

		
		
	


	



  Just got seriously sidetracked by other projects and had to wait to get matching
  black boards from the BiB Group Buy over at Diyaudio for Salas LV shunts regs.
  Next will be to put in on a breadboard and fire it up... just a matter of weeks.


----------



## cubeasic

Hallo guys,
   
  I´m quite new here in this forum and this is my first post.
   
  Is it possible to still get a set of boards for a EHHA Rev A?
  Maybe someone has one spare? 
   
  I have a lot of DIY experience, but mostly with non-headphone based systems.
  Now I would like to replace my OPA627 basedCMO derivative which I use for the last 2 years or so.
   
  So, if anyone could point me in the right direction?
   
  Thank you,
  Flo
   
  EDIT: Ok, I just found kits on glassjar audio... sorry


----------



## wdahm519

I just wanted to let you know I started this build on Monday.  Its my second tube amp build, and my 7th build overall.
   
  One question I had with the GlassJarAudio kit.  I was sent a bunch of identical diodes, where Cavalli calls for a few different diods, namely the 4004, and the 5313.  Any idea on this?  I forgot what # I got, I'll have to check.  I just know they're all identical.


----------



## wiatrob

wdahm519 said:


> I just wanted to let you know I started this build on Monday.  Its my second tube amp build, and my 7th build overall.
> 
> One question I had with the GlassJarAudio kit.  I was sent a bunch of identical diodes, where Cavalli calls for a few different diods, namely the 4004, and the 5313.  Any idea on this?  I forgot what # I got, I'll have to check.  I just know they're all identical.




You should have both the rectifier diodes (4004) for the power supplies and the CRDs (5313) for the input stage CCS. They're tiny!


----------



## wdahm519

Hmm that's not good.  I figured that was the case.  I do not have the 5313's as far as I can tell so I need to contact Jeff I guess.
   
   
  Thanks for your help.


----------



## funch

The 5313's have been discontinured for quite a while. The CRD Jeff uses looks like a two-legged TO-226.
   
  It's called a J511. Here's the data sheet, posted on page 90 of this thread. http://www.linearsystems.com/datasheets/J500.pdf


----------



## wiatrob

Quote: 





funch said:


> The 5313's have been discontinured for quite a while. The CRD Jeff uses looks like a two-legged TO-226.
> 
> It's called a J511. Here's the data sheet, posted on page 90 of this thread. http://www.linearsystems.com/datasheets/J500.pdf


 


  So it appears, my bad - time to update the BOM on the Cavalli DIY site, though the J511 is also listed as obsolete at Mouser. But it will work, if you can identify the part in Jeff's kit.
   
  EDIT: See post http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1290#post_7422832


----------



## wdahm519

Quote: 





wiatrob said:


> So it appears, my bad - time to update the BOM on the Cavalli DIY site, though the J511 is also listed as obsolete at Mouser. But it will work, if you can identify the part in Jeff's kit.
> 
> EDIT: See post http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1290#post_7422832


 


  So, my question continues.  I called up Jeff and he was really helpful, and knew right away that I needed to look for the J511 in my kit.  It was there, all was good.  However, later I stumbled on a different set of what also looked like J511's. 
   
  Basically, I have 4 CRD1's, one pair of them clearly says J511 on it.  the other pair has a J, and then on the next line it says 511.  The product code for the latter is something like C531_ but I can't remember the last letter/number.  The product code for the former is C090_ where I also can't remember the last letter/number.
   
  Which CRD1 should I use?  It seems as they may be the same because I don't need the second pair at all in the kit. 
   
   
  EDIT:
   
  I asked Jeff about this and he just said I got a bonus set, but to use the ones that were most obviously the J511's just in case.  Another happy customer of Glass Jar Audio.


----------



## wdahm519

Well, EHHA Rev A is now finished.  I'm listening to it right now.  It is an incredible amp!  I'll put some pictures... somewhere, in some thread...


----------



## hello im sean

Hey i've been looking around a bit for a complete BOM on this amp and i have a few questions.  Is the BOM on the cavalli website for this amp complete minus the enclosure? Also if itd be less expensive to order the parts individually ill do that otherwise ill buy the GJA kit.  However does the GJA kit have ALL included parts? if not what will i need.  Also it seems most people go MOSFET but is there an advantage to going BJT? some people seem to like it more some people seem to feel indifferent.  I dont know too much about the electronic difference so if anyone could explain that'd be great.. I'm a pretty good DIY'er but im pretty ignorant on what everything in an amp schematic is actually used for.  I just follow instructions well, id like to learn too though.  Anything i should know before i start? thank you, so much. 
   
  -Sean


----------



## sachu

GO with the GJA kit. It includes all parts needed to stuff the boards. I am not entirely sure if it includes an ALPS RK27 pot or not. CHeck with him.
   
   
  YOu will need to provide hardware, chassis, connectors, wiring to finish up the amp.
   
  GOod luck..its a great amp.


----------



## hello im sean

sorry but what do you mean by hardware? as in screws to mount etc.? and thank you!


----------



## sachu

yup


----------



## hello im sean

so is the GJA kit BJT based or FET based? and whats the electrical difference if somebody could please explain.  (dont know what BJT even means)


----------



## Beefy

Quote: 





hello im sean said:


> (dont know what BJT even means)


 
   
Try this.


----------



## hello im sean

hmm it led me to google, i believe google is a number not an answer? lol and i dont know what im searching for if all im typing is BJT >.<


----------



## stixx

Err, Google is a search engine...
   
  and it showed Bipolar Junction Transistor to me...
   
   
  Quote: 





> i believe google is a number not an answer? lol and i dont know what im searching for if all im typing is BJT


----------



## hello im sean

Quote: 





stixx said:


> Err, Google is a search engine...
> 
> and it showed Bipolar Junction Transistor to me...


 

 hey thanks man!


----------



## preproman

Can this amp be configured in a fully balanced design?


----------



## jdkJake

Yes, you just need four of the boards and a more capable (or dual) transformers.


----------



## funch

Doesl anyone here know of a replacement for the 2SC2705?


----------



## jdkJake

bdent has some:

http://www.bdent.com/2SC2705-p/2sc2705.htm


----------



## funch

Thanks Jake!


----------



## funch

I recently bought a mostly completed Rev. A from a member here, and discovered that VR+/- had been switched on one of the boards. I switched them to
  their correct locations and the PS outputs the correct voltages. However, the DC offset on that board is at -22VDC. 
	

	
	
		
		

		
		
	


	




 I've switched the TL081's around, and
  they both work fine in the second board. So my question is, what else in the servo circuit could have been damaged? Also, which components make up the
  servo circuit?


----------



## sachu

post your readings of the opamps pins on the board showing offset.


----------



## funch

Pin 1 = -14.81
  Pin 2 = 0
  Pin 3 = -15.29
  Pin 4 = -14.81
  Pin 5 = -14.81
  Pin 6 = 13.86
  Pin 7 = 14.94
  Pin 8 = 0
   
  Readings on the other board are essentially the same.
   
  Readings for Q10 on questionable board.      Q11
  Ground to G = -19.8                                    Ground to G = -26.3
  Ground to D = 29.6                                     Ground to D = -29.0
  Ground to S = 0                                          Ground to S = -23.1
   
  Readings for Q 10 on good board.                Q11
  Ground to G = -3.3                                     Ground to G = -2.8
  Ground to D = 29.5                                    Ground to D = -28.9
  Ground to S = 0                                        Ground to S = 0


----------



## sachu

Yeah,
  Looks like both your mosfets are blown.. Q11 for sure on the bad board.
   
  Check the voltage across R19.
   
  Measure voltages for BCE terminals on Q8 and Q9 for both boards.
   
  My hunch is YOu probably have Q9 blown on the bad board as well.


----------



## funch

R19 voltage is 6.6. I've got several SA1145/SC2705's ordered, so I'll just replace Q8/9. Do the voltages for the MOSFET's on the good board look OK?
  If so, I'll just replace them on the bad board. BTW, is it possible to use the same MOSFET's from the version 1 in the Rev. A? As in drop-in replace?


----------



## funch

Should Q6/7 pairs be matched? If so, how? Thanks.


----------



## funch

Found it in AMB's B22 doc's.


----------



## sachu

YOu shouldn't need to match them.


----------



## funch

Thanks Sachu. Since these things are cheaper than dirt, I ordered several to match just for the heck of it.


----------



## sachu

Quote: 





funch said:


> R19 voltage is 6.6. I've got several SA1145/SC2705's ordered, so I'll just replace Q8/9. Do the voltages for the MOSFET's on the good board look OK?
> If so, I'll just replace them on the bad board. BTW, is it possible to use the same MOSFET's from the version 1 in the Rev. A? As in drop-in replace?


 
   
   
  The good board looks okay.
   
  I am not sure on switching between the MOSFETs between the designs. haven't looked at the datasheets.. check to make sure.


----------



## funch

Well, now the good is the bad and vice versa. I had them powered up and realized that I'd forgotten to connect the ground wire from the 4-pin connector on each board. After powering
  down, connecting the ground, and powering back up, the boards switched personalities. Weird! I've decided on the shotgun approach and am going to replace all of the transistors on
  both boards. That'll learn 'em.


----------



## Sathimas

I still haven't finished my EHHA yet - due to lack of time.
   
   
  While going through the steps still needed to complete the amp, following question came to my mind:
   
   
  What's the power consumption of the EHHA Rev.A?


----------



## funch

Well, poo!  I powered up my amp today and left to let it warm up. When I returned about 15 minutes later, I could smell burnt. I quickly powered it down and removed the cover.
  The main power tranny (Avel toroid) was too hot to touch, and seems to have fried itself. I can find nothing else out of the ordinary with the amp. Anyone else here ever had
  something like that happen?


----------



## funch

Story continued here: http://www.head-fi.org/t/622598/burned-transformer-mystery#post_8610052


----------



## preproman

Balanced EHHA or Balanced Millet Hybrid Max?
   
  Whats the pros and cons to both?


----------



## Sathimas

@preproman: Can't help you on that question, sorry.
   
  But I have another question (already asked a while ago here...)
   
   
  How much power does the EHHA consume?


----------



## jdkJake

sathimas said:


> How much power does the EHHA consume?




Typically, for the MOSFET version, each of the output devices are biased to 100mA.

Since they are run class A, be sure to budget accordingly.


----------



## Sathimas

I got all the right parts (incl. transformers) with a kit from glassjaraudio.
   
   
  Just to clarify my question:
   
  How many Watt does it (2 channel, standard mosfet build) consume when running? 15W? 30W? 50W?
   
   
  I'm just curious and since it won't be able to finish mine before the end of this year I thought let's ask here.


----------



## jdkJake

sathimas said:


> I got all the right parts (incl. transformers) with a kit from glassjaraudio.
> 
> 
> Just to clarify my question:
> ...




That will depend upon what you pump through it.

You could calculate at the class A bias as a sustained load and then assume no more than a 2X increase over the class A bias and get a rough idea. So, assume 100mA per output device (MOSFETs biased at 100mA) and then again at 200mA. Don't forget to add in about 500mA for each of the heaters and that should give you a rough idea.


----------



## stixx

Since this thread has pretty much come to a screeching halt I might as well add something new.
  Over the holidays I was finally able to breadboard my EHHA RevA and fire it up.
   
  All went really smooth, rails of the Salas shunts are sitting at 30V, Mosfets are biased to the
  recommended 100mA and DC offset is hovering around 0.8mV in both channels.
   
  It only has a few hours on it so far (with my hacked off heatsinks reaching about 55°C, but I will
  add additional heatsinking once it gets cased up) so am not able to say alot about the sound...
  other than that it does the job really good. At first listening it sounds lightfooted, balanced and clean,
  highs are well integrated and bass is really deep and well controlled.
   
  More in a little while...


----------



## jdkJake

Looking good Stixx!

What brand of tubes are you using? Did you go with the standard gain implementation?


----------



## stixx

Thanks!
   
  For testing I put in a pair of Philips Miniwatt ECC86, but I also have Amperex 6GM8, 6N27P and some Valvo.
  I built it using the standard gain configuration but have the respective resistors socketed to play around later.


----------



## Sathimas

How high is the standard gain by the way?
   
  I'm also building one at the moment (takes way too long, but I don't have enough time ...)
   
   
  I fear the standard gain is quite high?
  Since I only have quite efficient cans at the moment, a gain of 2 would absolutely sufficient.
   
   
  And another question - do you have any chance to measure the power uptake of your amp?
  (See my question some posts before - I'm just curious 
	

	
	
		
		

		
		
	


	




  )


----------



## stixx

I seem to recall that the standard gain was around 9, but you can read up on it in that part of the thread --> http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1065...
  I will probably exchange my pre with a unity gain buffer (DCB1) as one of my next projects because all modern sources put out 2V.
   
  As for your other question I don't really understand it... do you mean the power consumption of the amplifier? This has been explained on the Cavalli site (which seems to
  be down at the moment (?), but as jdkJake already mentioned: when I'm right you need about 200mA per channel for the Mosfets and a little extra for the rest, so make that
  250mA at 30V for the amplifier and about 500mA for the heaters (per channel). I specced my toroids at 2x27V/0.6mA and 7V/0.5mA per channel. I had them custom wound
  at RONDO Müller, and they are of excellent quality at a good price


----------



## jdkJake

stixx said:


> Thanks!
> 
> For testing I put in a pair of Philips Miniwatt ECC86, but I also have Amperex 6GM8, 6N27P and some Valvo.
> I built it using the standard gain configuration but have the respective resistors socketed to play around later.




You will have to let me know what you think of the 6N27P. Both myself and bk_856er really enjoyed their sound.

Sounds like you have a very flexible build with lot's of nice tube options.


----------



## jdkJake

sathimas said:


> How high is the standard gain by the way?
> 
> ...
> 
> Since I only have quite efficient cans at the moment, a gain of 2 would absolutely sufficient.




As stixx stated, the standard gain is around 9. I have taken it down to around 5, but, not any lower. If you shoot for 2 be aware you may need to play around with the compensation caps to keep it stable. Perhaps Alex will chime in on the potential to take the gain down that low.


----------



## muskyhuntr

Glad this thread started again.  Started soldering mine yesterday.  Unfortunately, this will be a lower priority until I finish my AMB M3.  For the most part, my build will be done using parts supplied in the Glass Jar kit though I am open to some minor mods.  One that I am considering right off the bat is using SumR transformers, but have not decided yet.
  Another is using a 10,000 uF cap. for C1H in the heater supply.  I already have a few and they fit in the holes perfectly.  Any pros or cons considering this change?
  I would be interested to hear of any changes made by you guys before I solder in the parts  esp. in the caps department.   Tubes and opamps can come latter.
   
  Stixx, I see that you had a M3.  I would be interested in your thoughts comparing the EHHA and the M3.  BTW, yhe casing you did on the M3 was first rate!
   
  Thanks


----------



## Sathimas

Thanks for the advice, stixx.
   
  I didn't say I wanted to cut down the gain to two, just that it would suffice.
  I'll try the standard gain, my alpha20 preamp has a gain of eight, what works o.k. too.
   
   
  Power consumption should be arround 21watts then?
  (I studied medicine, doctors are really bad in calculating     )


----------



## stixx

Quote: 





> Stixx, I see that you had a M3.  I would be interested in your thoughts comparing the EHHA and the M3.


 
   
  OK, one reason I sold the M3 is that I am running out of space with currently 5 (6) headphone amplifiers in my possession 
	

	
	
		
		

		
		
	


	




.
  The other is that even it sounded very neutral it always seemed to lack something... I just didn't get the same close feeling as
  with tube amplifiers. Maybe it always sounded a tad technical, sterile. Don't get this wrong... it is still a world class amp and the 
  new owner (driving K1000's with it) is very happy! 
  The EHHA on the other side has a better balance, even though it doesn't have a lot of mileage on it. And it has the advantage of
  tube rolling etc. So my vote between the two goes to the EHHA RevA 
	

	
	
		
		

		
		
	


	



   
  And btw. when those big caps fit nicely put them in... filtering heaters can never be enough.
   
   
  Quote: 





> Power consumption should be arround 21watts then?


 
   
  Yes, but you want to double that just to be sure. Where will you get your transformer(s)?  A 2x30W toroid is not that easily available
  in Germany, so that's why I am asking. A 30-0-30 40-50VA should be fine, but then you need a second one for the heaters. Thats why
  I had mine custom wound...


----------



## Sathimas

I got the two transformers together with all the rest as a kit from Jeff Rossel (Glassjaraudio).
   
   
  I can't wait to see pictures of your finished amp, since your builds where always really cool!


----------



## stixx

Thanks Matthias,
   
  But this will take some time...
  Will you finish your EHHA the same way as your SOHA?


----------



## Sathimas

The EHHA will look like this:
   
   

   
   
  I'll be using mdpc-x sleeve for all the cables inside to give it some
  technical-alien-look :-D


----------



## stixx

That is looking very cool!!
   
  And suits my own taste perfectly... I also love to combine different materials
  and warm and cold (plexi and wood).
   
  Instead of becoming a doctor you should have studied Design ...


----------



## Sathimas

Wait until you see my patients after I'm finished with them 
	

	
	
		
		

		
		
	


	



   
   
  But I have another question: 
   
  How do you guys get your boards that clean and shiny?
   
   

   

   
  This is what one of my boards looked like after cleaning it with 99.5% Isopropanol.
  I mean most of the stains from the flux are gone, but it still looks dirty.
  (Not to speak of the ugly traces on the top side ...)
   
  Do I need to use simply more of that stuff?
  Or mix it with something else?
   
  Since one will see a lot of the boards in my EHHA, they have to be really clean this time!


----------



## BK_856er

That's the right solvent - nice high purity.  Use more of it, and go back 3-4 times if you need to.  Use an old tooth brush and/or cheap acid brush to help loosen things up mechanically.  Blot the wet surface with paper towels and discard.  For the final rinses you'll want to use clean solvent. You can even dip the board into a shallow container and slosh it around, but I always worry about getting the trimpots too wet, so be careful with that. I've never used the spray cleaners due to their cost, but I imagine they are also pretty effective.  Give plenty of time to air dry before powering up.
   
  In short, do what you've been doing, but repeat a few times.  No doubt it's a nuisance.
   
  BK


----------



## tomb

Quote: 





sathimas said:


> Wait until you see my patients after I'm finished with them
> 
> 
> 
> ...


 
  It takes a half-dozen rinses sometimes - depends on the number of parts and the amount of flux residue.  You need to pick up the dissolved flux with paper towels each time, though, while the alcohol is still wet.  Or else the flux goes nowhere but dries back down on the board.
	

	
	
		
		

		
		
	


	



   
  BK_856er has some good points, too - use an old toothbrush to break up the really bad flux deposits.


----------



## Sathimas

ok - I've been on the right way then 
   
  I did already use a toothbrusch.
   
  I was just wondering if the Isopropanol was really the best solution.
  So I'll just reapeat the procedure and try to use some paper towels.


----------



## Sathimas

Another question came to my mind while I was planning the final inner layout of my ehha.
   
Do I need an e12? (Or two, to be exact)
   
I see some users use one, but many do not.
  One time I read it's a must, the next time people say it's just to be sure...


----------



## stixx

Quote: 





> I see some users use one, but many do not.
> One time I read it's a must, the next time people say it's just to be sure...


 
  This is like buying health or life insurance... people recommend it but you can live without.
   
  I have yet to encounter a malfunctioning amplifier that takes out my headphones... tubes don't
  have the problem anyway and even my M3 did perfectly without an e12. The noise generated
  when you switch it off is so tiny and unharming in comparison to the levels some people use
  for daily listening ... 
	

	
	
		
		

		
		
	


	




 My breadboard EHHA RevA also doesn't have one.


----------



## Sathimas

If I recall correctly, the EHHA was said to have some relatively high dc offset 
  after switching on, which might be dangerous - but if there's nothing audible ...
   
  I'd also prefer not to use an e12, keeps wiring simpler and saves space
  inside my already kind of small case.
   
  By the way - my boards are almost perfectly clean now


----------



## nonamodnar

Hi DIY-ers,
  I have a question for the EHHA Rev A case. After reading the whole thread, I decided to take on this project in a near future to couple with my ODAC and Paradox. I will probably go with the kit from GJA (does the kit include the PCB or power adapter? Or do I have to order them separately?).
   
  I know there is no definite case for the EHHA and I've seen many amazing ones in this thread. Since I have no access to a milling machine, I guess my option is to buy a machined case from somewhere else. Do you have any suggestion?
   
  Thanks,


----------



## Sathimas

> I will probably go with the kit from GJA (does the kit include the PCB or power adapter? Or do I have to order them separately?).


 
   
  Maybe you should read a bit more about the EHHA rev. A first 
   
  The Rev.A PCB includes power supplys for each channel separetely.
  Jeff also supplies you with the torroids you need, so you just need to add
  an power inlet (110/220 - where do you live by the way?).
   
  As for cases - just use the search a bit, there are many different suppliers.
  A can highly recommend hifi2000 from italy, but shipping to the US is expensive.


----------



## nonamodnar

Thanks Sathimas. I live in the US so I guess 110V for me. Is there any supplier for cases in the US that you know of?


----------



## funch

It seems as though Par Metal is back up and running after the fire they experienced.
http://www.par-metal.com/
   
  The 20 Series cases are what most everyone here has used in their builds. I've done two myself, using a 12x12x3 size. You should use
  1/4" tall circuit board standoffs for this case size.


----------



## nonamodnar

Thanks funch, I'll check that out.


----------



## daigo

I'm a pretty novice DIY (I've only built small and simple devices like a CMOY and a mini^3) but I'm also thinking about picking up an EHHA kit from glassjaraudio to scratch the itch for new gear and avoid buying something else.  Reviewing the pcb on the EHHA rev A, it seems like a step up in difficulty that I think I could work my way through if I take it slow.  Am I delusional for thinking about trying this out with my limited experience?


----------



## BK_856er

Sounds like me:  cmoy --> mini3 --> EHHA revA.  Take your time, lean on the helpful folks here if required, and you'll have no problem.  Set aside some time for chassis work and wiring (that'll be new compared to your prior projects).  Go for it - great amp!
   
  BK


----------



## stixx

I have started much bigger many years ago and didn't run into major problems... when you take your time, ask before you proceed with something unknown and employ your best soldering skills it definitely can be done. Layout is quite tight on the EHHA board so always check parts values and designations /orientation before soldering... put it in a nice case (Hifi 2000/Parmetal as mentioned recently) and you'll have a great amp!


----------



## muskyhuntr

Hi All;
   
  For some reason, this sight won't let me post pictures so a written dialog will have to do. Plugged my in EHHA  about  2 weeks ago for the first time.  In its present shape, its a tangle of wires on a 12x12 plywood board.  Minimal thought to EMI and grounding. Gave it a few hours break in with some 1K Hz square waves  and a final bias adjustment  to 220 mV before the first listen.  To be honest, it sounded cruddy.  Bass had a little promise but every thin else stunk!.  The more complicated the music, the worse it sounded. Decided to give it another 5 or 6 hours before the next listen and still blah!  Scope traces for both square and sine waves were not good to say the least.  I decided to let it burn for another 8 or 9 hours while I made plans for my favorite pass time...trouble shooting.  Returning to my shop, I noticed the traces on the scope looked really good.  Reset the bias to 220 mV and gave it another listen.  In one word "AWESOME".  This thing sounds better than great!  Even with the sloppy temporary wiring, the amp was dead quiet.  For those interested this is a stock build from Glass Jar using Mosfet's and 6GM8's for tubes.  Right now I am deciding on how I want to case it up.  Final version will have a TKD pot,  SUMR transformer, and Vampire connectors.  I've been looking around Ebay for some tubes to roll it with.
   
  Hopefully I can figure out the picture problems before I finish casing it up.
   
  Jim


----------



## muskyhuntr

Hi All;
   
  Did a little work on my enclosure with with the new 4.2 version of Front Panel Designer.  (This new version is not as stable as the previous release.  Crashed a number of times.  Will not save files created in previous versions. Other problems! Beware!)  Also, still waiting on the SUMR transformer before finalizing any design decisions.
   
  Whats a person to do.  Tube roll!  I received 4 6N27Ps in the mail a few days ago.  Vintage 1969's.  I randomly selected 2 and placed them into the amp for some break in time.  After about 10 hours, I gave them their first listen.  Much worse than the 6GM8's sounded!  Indeed, would have sounded better if I had threw them on the floor just to hear them pop!  Any who,  came back for subsequent listens until after about 25 hours, they gave up their stubbornness  and sounded really good.  Their tonal quality is a bit different than the 6GM8s, but they sound really really good.  Score: Good tubes 2....Bad tubes 0.    
   
  I have a pair of 6DJ8's coming soon to try out.  Also looking for the elusive Telefunken 6GM8's.  Will keep you all informed.  Still can't post a picture, but...maybe someday.
   
  Jim


----------



## muskyhuntr

Hi Again;
   
  Finally letting me upload some pictures!
   
   

   

   

   
  Getting there!
   
  Jim


----------



## Klechty

Hi there,
   
  i bought a mosfet EHHA rev a.
  As i was not satisfied about the components layout, especially the power transistors, i made a pcb.
  I also reviewed some components sizes, psu capacitors, and the J511 constant current diode.
  i also used an R-core transformer.
  It is only for my personnal use to satisfy myself.
  here are some pics, it is actually not finished , because i burned my opamp during my tests :
   
   
  http://hpics.li/3fb3dd4
   
  http://hpics.li/3f0e9c7


----------



## jdkJake

Klechty,

A most interesting take on the build.

How high are you planning to bias the MOSFETs such that you went with the external heatsinks? Or was it more of an aesthetic reason?


----------



## Klechty

Hi,
   
  there are some trimmers on the pcb.
  Also i can set up my + -30V.
  I made a new pcb to use with ECC88 .
   
  Thanks for the interest.


----------



## newbienewbie

Hi guys, 
  I'll be doing the classic newbie thing and introduce myself with a silly question. 
  I just started getting together the parts necessary for the build and I messed up something in the communication
  with my supplier about the transformers, so instead of getting a center tapped 30-0-30 toroid,
  I got two regular 30V (10 VA). Can I make them work somehow as a + - supply or do I have to
  order a new transformer? Unfortunately I made the mistake, so I can't claim a refund.
   
  Any ideas?
   
  One more thing the 1N5313 diode no longer seems available.
  Can I replace it with 1N5314? They are quite close in specs.


----------



## newbienewbie

An answer to either question would be great.


----------



## holland

Quote: 





newbienewbie said:


> Hi guys,
> I'll be doing the classic newbie thing and introduce myself with a silly question.
> I just started getting together the parts necessary for the build and I messed up something in the communication
> with my supplier about the transformers, so instead of getting a center tapped 30-0-30 toroid,
> ...


 
   
  Yes, you can use 2 transformers to make a split rail.  It just uses more space.  What PSU are you using?  You can connect them from the secondaries or connect them after the rectifier.  I think people prefer connecting after the rectifier.
   
  1N5314 is fine, though the E452 might work better.


----------



## newbienewbie

Hi, thanks for the answer - I assume that by e452 you mean this: http://cpc.farnell.com/1/1/29753-diode-current-regulator-4-5ma-e-452-atc-semitec.html ?

I planned to use PSU that is part of the PCB. Sorry, but I am not sure that I understand how could I connect them after the rectifier? The toroids are AC.


----------



## holland

If using the stock PSU, connect the secondaries.  I presume the transformers are identical.  Let's say they have 2 leads each, blue and green.  Connect them like this.  Blue, then Green+Blue, and Green.  Green+Blue would be connected to ground on the PSU board.  Double check with a DMM.
   
  Yes, on the e452.


----------



## newbienewbie

Yes, the transformers are identical (at least they should be.  )
If they are not _exactly_ identical, could that cause a substantial problem?

Unfortunaly the secondaries on both are just two black wires - so I would have
to find out which is which first. 

So, if understand correctly since the green line is 180 Deg out of phase with the blue one
(which creates the required + - supply) then the green and blue connected together 
cancel each other out - thus creating a ground?

Just to make sure: you suggest that I connect the secondaries in series and the
DMM between green and blue should read 60v.

If I make the mistake and connect them parallel DMM should read 30v.

The primaries should however be connected in parallel.

I maybe saying very stupid things right now, but my knowledge of AC current is close to 0.


----------



## techboy

Where can I find a EHHA Rev A builder? Also, how much would it cost for a builder to build it and ship it to me? Can you help me find a builder or point me to somebody who could help me further? 

Aakshey


----------



## holland

Quote: 





newbienewbie said:


> Yes, the transformers are identical (at least they should be.
> 
> 
> 
> ...


 
   
  I don't believe so, but I've never done it.  You'll be restricted in current limits to the lower of the two, but the voltages should stack...at least between secondaries on the same transformer.
   
  Quote: 





> Originally Posted by *newbienewbie* /img/forum/go_quote.gif
> 
> So, if understand correctly since the green line is 180 Deg out of phase with the blue one
> (which creates the required + - supply) then the green and blue connected together
> ...


 
   
  It's like connecting batteries, although there is phase, for the example you can ignore it.  You can't connect them in parallel, as the configuration is for series.  Parallel would be green+green and blue+blue.  If you connect them wrong, you would get 0V.  Before you connect, you should check the phase with a DMM.
   
  Transformers float.  Ground is just a reference point, whatever you want to make ground.
   
  If you have problems, you could just make 2 PSUs and connect them on the DC side.  Honestly, if you're tackling this you should be able to read a schematic and know how to debug a circuit and be self reliant.  These forums are pretty much dead, and getting support is going to be spotty.


----------



## newbienewbie

Thanks for the support holland,

I know that I am biting of more than I can chew right now, but I wanted this to be a bit of a challenge
so that I can learn some things along the line. I can take it easy and one step at a time.  
Again, thanks a lot!


----------



## holland

Quote: 





newbienewbie said:


> Thanks for the support holland,
> 
> I know that I am biting of more than I can chew right now, but I wanted this to be a bit of a challenge
> so that I can learn some things along the line. I can take it easy and one step at a time.
> ...


 
   
  No worries.  Just be aware that there might not be anyone here to help you much.  If you can work out voltages and current via pen and paper (i.e., EE student), you should be fine.  Also, make sure, that if you check the secondaries (not connected), that you do get 0V at some point.  If you get some small voltage, you may have some phase issues and noise.
   
  Quote: 





holland said:


> I don't believe so, but I've never done it.  You'll be restricted in current limits to the lower of the two, but the voltages should stack...at least between secondaries on the same transformer.


 
   
  I think I might be wrong, after mulling it over.  Off the same transformer, connecting secondaries is OK (say a 10V secondary and a 20V secondary).  There may be a problem connecting 2 separate transformers, say a 15V transformer and a 100V transformer.


----------



## Klechty

i prefer to use lm334 and choose my current .


----------



## Klechty

newbienewbie said:


> Thanks for the support holland,
> 
> I know that I am biting of more than I can chew right now, but I wanted this to be a bit of a challenge
> so that I can learn some things along the line. I can take it easy and one step at a time.
> ...


   


   
  you have a PM :d


----------



## muskyhuntr

Hi All;
   
  Finally finished casing my amp.  Moving from the plywood base to it's final enclosure some how caused the amp to hum a bit.  Nothing major.  Problem was fixed by using a ground loop breaker on the input grounds.  Dead quiet again.  Settled on the Amprex 6GM8's as sounding the best.  Still looking for the Telefunkens.  As was my M3, casing was inspired by a design of Stixx's
   
  Some pictures:

   

   
  A few inside shots:
   

   

   

   

   

   
  Next up is The Christensen Damn Good 300B.
   
Jim


----------



## BK_856er

Outstanding, muskyhuntr.  First class build.
   
  I have a couple NIB pairs of telfunken if you're interested.
   
  DG300B = diy has its grip on you.  What cans you using?  Would like to try that one myself.
   
  BK


----------



## stixx

Very nice build, Huntr! And thank you for the credits...  That's a very clean execution... I especially like the top cover with the tubes popping through and the use of the TDK pot. When I may add a tiny bit of critizism I would tidy up the wiring some... or wrap the wires in braided sleeves now that you have established all the connections. I have yet to case my EHHA Rev A up... it is playing music on the breadboard (doing great with my freshly aquired HE-500's) but I am still struggling with a theme for the case. Maybe its gonna be in the Stealth direction... matte black with a few accents


----------



## muskyhuntr

Hi All;
   
   
  Quote:BK_856er 





> DG300B = diy has its grip on you.  What cans you using?  Would like to try that one myself.


 
  For the most part, I use Senn 600 hds.  However, I was at a meet a few weeks ago and brought the amp before it was 100% complete.  I was able to try it with a number of different cans, though all sounded good, a set of Grados and a pair of Beyer 880s (250 ohm) stood out.  My DG300B is being built to drive speakers in a small room but there is a thread on this board where the builder is using it for head phones.  He is having a few problems, but I think they are mostly from the builders choices and not the designers.  As for the DIY bug, your right!   _I should probably seek _medical help!  Not only am I working on the DG300B but I'm also at various stages with an Aikido pre amp (dual chassis, fully dual mono) and a B24 by AMB.  Would like to do a set of speakers and if AMB ever finishes his high end DAC, I would do that in a second.  Being retired helps.
   
  Stixx:
   
  Your right about the wiring.  Looks almost like a point to point!  I do plan on cleaning it up though.  Haven't used braid before, should be interesting!  I used all the wrap I had on a pair of the AC secondaries. But this does lead to my one complain about this amp.  There is a ton of wiring external to the boards. If the pc boards are left in one piece, the wiring can be a bit neater.  But even then, you have to run wires that could have been better implemented as traces (the filament wires for example).  When you break the boards, the problem becomes worse.  I was rigid on the case design as I wanted it to match my M3, so had no choice but to break them helping to increase the wiring's complexity.   Also, because of all this, hum was my biggest fear during construction.  As I pointed out, the amp was dead quiet on a piece of plywood, but had a bit when installed in the case.  Easy fix though.  There is a plus to this design as it allows for flexibility in a final lay out, which I took advantage of. This is a minor criticism and in no way detracts this from being a great amp.  It has a super reputation and in my opinion, well deserved.  By the way, I plan on using the housing design one more time on the DG300B,  my other projects will be more traditional. 
   
  Thanks all,
  Jim
   
  PS; Looking forward to seeing your project completed!


----------



## nickodj

hi, is anybody that have this amp also have he-500 and used them together and can give any impression about it? thanks


----------



## stixx

EHHA RevA and HE-500 is a great match...
  I recently got a pair of HE-500's from a fellow HeadFi'er to do a step up from Sennheiser HD600/650... and yes it is!


----------



## Sathimas

I am finally close to finishing my EHHA
  
 Now I have a problem early in the initial check:
  
 I connected and powered one heater supply without any problems.
 (LED light, voltage is correct, tube lights, voltage stable at 6.3V)
  
 Now when I power up the second heater, the LED ist not as bright
 as the the other one and slowly get's dark then. I also don't get the
 right voltage on the output.
  
 I did already check the diodes (All ok) and compared the resistors
 values (all the same).
  
 Where might my problem be?


----------



## Sathimas

Just measured the input voltage and found only 7.xx Volts on the non-working heater.
  
 Strange, have to check the wiring again.
  
 The secondary windings of the torroid are 
  
 black+red: 9V @ 1.67A
 orange+yellow: 9V @ 1.67A
  
 I get about 9V from orange+yellow, but only 7.2 from black+red.
  
  
 Very strange!!
  
 Might the transformer be damaged?


----------



## stixx

Hi,
  
 Strange indeed. It should not matter how you connected the two wires...you should have more than 10V
 at the input. Could it be that one of your toroids is a 6V unit?    
	

	
	
		
		

		
			




  
 OK.. stupid reply since you have a toroid with two secondaries. Have you rechecked your readings and
 have you tried with reversed connection?


----------



## Sathimas

First - a small preview what it's gonna look like 
  

  
 Now - the two secondary windings are both 10.3V without load,
  
  
 I did reflow all the solder joints and it works correctly now ...


----------



## Sathimas

No easy win here...
  
 Attached the rest of the wires and found that the DC-offset on the right channel
 does not drop - I'm reading 24V across G and OUT.
  




  
 The other channel is working fine.
  
  
 Since I'll be going on holidays tomorrow I won't be able to do any more testing,
 but nonetheless I'd be very happy about some hints where to start looking for the error.


----------



## funch

I purchased a semi-completed Rev A that had offset issues. It turned out that there was a cold solder joint on one of the resistors.
 I believe it was R12 iirc.


----------



## jdkJake

sathimas said:


> No easy win here...
> 
> Attached the rest of the wires and found that the DC-offset on the right channel
> does not drop - I'm reading 24V across G and OUT.
> ...




How about some pics? Top and bottom, as much light and focus as you can muster.


----------



## Sathimas

I won't be able to post some pics before the 23.09.2013, since I'm on holiday right now
 (And getting married this saturday   )
  
 But I can't wait to get this amp to work, since I'm working on it for about 2 (!!!!) years.


----------



## stixx

> First - a small preview what it's gonna look like


 
 very nice wrap job... looks like a can of worms.. or human internals.
 You must be a surgeon then 
	

	
	
		
		

		
		
	


	




.
  
  
  
 And CONGRATULATIONS to your wedding!


----------



## Sathimas

Here are the requested pictures, hope the are sufficiant.
  
 I did also reflow all the solder joint, but still the offset is at 25V !


----------



## stixx

No expert in troubleshooting solid state stuff... your soldering quality looks really good, and as far
I could see parts orientation and such is all good also.
Did you check your DMM...? They can be faulty, and 25V offset is very high. Maybe also check that all 
your semiconductors are in the good place on the pcb.

Good luck!


----------



## Sathimas

DMM is definitely o.k. - I did the initial check of all other boards with that one.
  
 I'll try to check the transistors too - always possible to have them in the wrong place...
  
 It's a pity runeight himself isn't present here anymore...
  
 But i don't know where to ask anywhere else...


----------



## gurubhai

Here's how I would have go about troubleshooting.
  
 1) Look for any shorts
  
 2) Double check all components.
  
 3) Check the BJTs using the BJT sanity tutorial an amb forums :
 http://www.amb.org/forum/howto-bjt-sanity-check-t59.html
 If there is some confusion , compare the results with the other working board.
  
 4) Check & compare the resistances of output mosfets
  
 Replace the faulty devices and see if you can get it working.


----------



## holland

http://www.elexp.com/t_test.htm
  
  
 Diode test your transistors, something is probably blown.  I would start with the VAS stage and servo booster, Q6, Q7, Q8, Q9, Q12, Q13, Q14 and Q15.  Another thing you can try, just to get bearings, is to pull the servo on both channels and measure voltages at different points, especially on the current mirrors.  Make sure the trimpot is set at the half way mark first.  Do note that some of the transistors in the current mirrors are set up to be a diode drop.  They will look like the attached.  When you diode test, that part will appear as a short, and should test exactly like a diode (such as 1N4001).
  

  
  
 I haven't checked your pictures since stixx said it looks good.


----------



## Sathimas

I'll be back with results as soon as I can, but do not have the time today or tomorrow,
 so don't check for results before friday here.
  
 Thanks for the advice so far.


----------



## holland

No worries.  Just make sure you are looking at the schematic as you are doing this.  Results can vary depending on how transistors are wired.  That said, you can brute force it and change a bunch of transistors for the heck of it, but that can be a big PITA unless you have a desoldering station.


----------



## Mullet

I'm about to embark on my EHHA Rev A journey. Been waiting for a while -- built "The Wire" and a really nice ES9023 based DAC first. I'm planning on using the E12 and have used it in the past with the CTH. With the CTH I had to lessen the threshold for when it triggers. I still even find with certain headphones, the AKG K240 Sextetts for example, that it's pretty easy to get the E12 to trip. I'm thinking this might have more to do with the implementation in the CTH vs. other amps. Some tubes are worse than others. Other headphones don't have the issue as much. For example, orthos don't cause the CTH E12 to trip that easily or at all. What are everyone's experiences with the E12 in the EHHA Rev A? Did you guys find that upping the tripping threshold was required? Also, has anyone tried the EHHA Rev A with the Sextetts? If so, are they a good match? I figure I'll wait til January or February before I buy my kit from Glassjar. Just want to have my research all in order first. I'm thinking at this point socketing all the OL and CL gain resistors and going with an initial gain of 5 or so.


----------



## BK_856er

I run dual E12s on my EHHA RevA and have no issues using the AMB default values with LCD-2s.
  
 I had some early annoying quirkiness on one channel, but after I redid all the molex crimping that went away.
  
 If I recall correctly, the E12 will trip if I sweep the volume knob really fast with the headphones unplugged, but that's not normal usage.
  
 Nothing against glassjar, but can you still get just the EHHA RevA boards and spec your own parts?
  
 BK


----------



## Mullet

Laziness? I know it's fun to spec your own parts -- I've done it plenty with some of my projects as of late. Sometimes expediency is your best friend. No fuss no muss. I think going thru Glass Jar should be overall cheaper. Although with some of the extra parts ie resistors sockets, e12 parts, etc. then the cost will jump up a little more. I'm not sure I'm going to go the par-metal case just yet, but it surely will be the standard 12x12x3 size everyone seems to like. I'm thinking of going with my source of custom aluminum/wood chassis in Oregon, if he's still making them.


----------



## muskyhuntr

I also run dual E12's.  I found that until my amp stabilizes (about 5-6 minuets) they are very touchy, sometimes tripping with volume adjustments (fast or slow), moving the volume past 12 o'clock, or even on it's own.  After that the E12's are very stable.
  
 Jim


----------



## jdkJake

I have no issues with the e12 using the standard values. That said, there are multiple versions of the e12 out there. I am using the v1.2 boards without any issue. I did have to recalibrate them after the first week or two, but they have been fine since.

You might want to consider building the standard gain first and then backing your way down. Or at least build the standard gain first and then swap out to a gain of 5. The sound does change a bit as you fiddle with the gain resistors. I would have a number of values on hand until you find the combination you like best with the gain that fits your system.


----------



## Mullet

@jdkJake I'll most likely do the default gain or at least have the parts on hand for it. Don't want to shoot myself in the foot -- hence sockets for everything. I read your earlier posts and took some notes on what to do in terms of gain settings. I'm thinking at the start going for 3 different combinations and seeing what works best. I like to have some ride on my volume knob -- ideally, but if I like a certain sound vs. ride on the pot I'll go for sound.
  
@muskyhuntr It's good to know that they stabilize. After things settle, do the e12s still trip with high impact transients like drum beats, etc?


----------



## muskyhuntr

Once the amp stabilizes, I have never had a problem with the E12's tripping.  I listen to a wide variety of music including Japanese drum music-Kodo, and have never had a problem.  This is a nice amp!
  
 Jim


----------



## Ony38

Someone make a long comparison between Mofset ans BJT version ?

I start thinking to building a balanced EHHA rev A...


----------



## Mullet

People have been asking for a comparison for quite a long time. I'm sure there are at least one or two DIYers that have built both. I know Sachu had built an EHHA I with BJTs and an EHHA Rev A with mosfets. Reading in the EHHA thread, I thought I read that the BJT version would allow you to modify the amp to be able to drive small speakers. With the BJT it looks like you can use a few different varieties from different manufacturers. Toshiba seem to be the most popular. On Semi are the ones in the BOM. I'm not sure why the BJT would be better than a Mosfet other than the ability to have a higher powered amp for speakers.


----------



## jdkJake

Careful and judicious use of sockets would allow you to build a unit that would support either set of output devices.

In that manner, you would be able to decide for yourself which set of devices suits your tastes best.


----------



## Mullet

runeight said:


> MHO is that device matching is not needed. The Toshiba transistors should be selected in the same hfe class though.
> 
> If I were matching I would match two things.
> 
> ...


 

 I know this post is from way back in 2009. But I'm a little curious about tube matching, even if it's not utmost necessary.
  
 I have a local guy that sells tubes out of what I deem to be a large garage. Place is a veritable rats nest, but this guys knows where everything is. He says he has 6GM8s. Not sure what brand, etc. but he was asking what % I want them matched to. This is what he asked...
  
 "By matched pair do you mean with matched electrical characteristics? If yes, how closely matched, in percent and which parameter(s)?"
  
 If I chose to go this route, what should I tell him? So the mu is the only thing that should match? Would I get a weird look if I asked for this?


----------



## Mullet

jdkjake said:


> Careful and judicious use of sockets would allow you to build a unit that would support either set of output devices.
> 
> In that manner, you would be able to decide for yourself which set of devices suits your tastes best.


 

 Wouldn't that increase the overall height of the heat sinks on the mosfets, hence a 4" height for chassis?


----------



## Ony38

Thanks guys for the answer, I will come back on the EHHA when I will finish my Monolith and my Wire Bal-Bal & Se-Se


----------



## jdkJake

mullet said:


> I know this post is from way back in 2009. But I'm a little curious about tube matching, even if it's not utmost necessary.
> 
> I have a local guy that sells tubes out of what I deem to be a large garage. Place is a veritable rats nest, but this guys knows where everything is. He says he has 6GM8s. Not sure what brand, etc. but he was asking what % I want them matched to. This is what he asked...
> 
> ...




Does he have a tube tester? If so, what parameter(s) does it test?

Since you are most likely not testing the tubes at the operational parameters in which they will be used, the best you can do is approximate their relative performance against a known reference; hence the tube tester.


----------



## jdkJake

mullet said:


> Wouldn't that increase the overall height of the heat sinks on the mosfets, hence a 4" height for chassis?




The use of sockets should not have any bearing on the chassis height. The legs of the output devices would be trimmed appropriately to fit the heatsinks while retaining a tight fit within the sockets.

Ideally, or at least how I would do it, the heatsinks themselves would not be soldered down, rather they would float or use a screw to hold them in place. The output devices would be mounted to the sinks and would be trimmed to firmly seat into the socket. In this manner, the output device and heatsink would form a replaceable combination. This would require two sets of sockets. One for the BJT side and one for the MOSFET side. Overall height should remain the same as the heatsink is the same regardless of device, they just mount of different sides of the heatsink.


----------



## Sathimas

My EHHA is slowly coming to life now...
  
 After checking all the parts together with a friend of mine
 (and finding nothing wrong) I just re-wired everything, double-checked
 proper isolation and so on.
  
 Now the offset still rises up to 25V on the right channel but
 drops down to ~1mV after three or four secounds - and stays there.
  
 But the high offset in the beginning still troubles me.
 The other channel only rises to ~200*m*V.
  
 I am also in contact with Mr. Cavalli himself, let's see if I can find the error.
 ( I have to, since there's no space for e12s inside   )


----------



## jdkJake

Well, that certainly is not expected.

What does your bias measure on each side?


----------



## funch

I also had a channel on a Rev.A that had high offset. It turned out to be a bad solder joint on a resistor, which I believe was R12, so you might recheck
 all of your joints. The bad one on mine looked perfectly fine until I pushed down on the top of the resistor, when I discovered that the solder didn't adhere
 to the board foil. Sneaky little bugger.


----------



## Sathimas

The problem is coming from the tube itself - swapping the tubes
 brings the high offset to the other board and vice versa.
  
Bias is ~200mV each side after warming up.
  
  
 Alex says that this is within the normal behavior.
 The servo has to be that slow.
  
  
 Well, seems that I will have to get an e12 and stuff it into the
 already packed case  (There's room left, but wiring is tricky)
  
 What brings me to another question - why do you use two e12s for the Ehha?
 The relay can delay up to four channels - so one board should be sufficient?
  
 Nonetheless - I'm happy that the amp lives now :-D


----------



## Sathimas

I'm back with another problem.
  
 I have now wired the inputs, the pot and the headphone jack.
  
  
 It plays music without any flaw - but I have a very loud hum one the left
 and a more quiet one on the right channel.
  
I used wiring method one and all the signal carrying wires all fully shielded.
  
  
 I'll post a picture of the inside of the amp tomorrow.


----------



## jdkJake

You do not have to use an e12. You could just let the amp warm up and the bias settle before plugging in the headphones. I would advise you do that anyway, even with an e12.

You need two e12 as the EHHA rev A boards have independent power supplies. One e12 for each supply. You could get by with one, but, it is not an optimal solution. There is a complete discussion on this topic earlier in the thread. I would suggest you search it out and read the various opinions.


----------



## stixx

Hi Sathimas,
  
 the hum problem you are describing most possibly is a grounding issue... like a ground loop because you have two ground points (probably not) or something else.
 In one of my builds I had hum because I attached the shield of the input wiring on both sides... duh. Took me forever to find it (glad it's years ago 
	

	
	
		
		

		
			





).
  
 Anyway good to hear that your EHHA is playing music now!


----------



## Sathimas

Concerning the offset - of course I could always disconnect phones.
 I'll do that anyway.
  
 But I also use the EHHA as PreAmp for my active speakers 
 AND I am not the only one using it, my wife has a bad influance
 on technical gear 
  
 So it's just to be sure - and to have the delay.
 I also understand why I should use to of them after some reading,
 but as you see, the case is more than packed and two would not
 really fit. (The small sheet of paper is about the size of an e12)
  
  
  
 Concerning the hum:
  
 First, a picture:

  
  
 I have one star ground, all ground connections got to that point
 and from there another wire goes to the ground connector on the AC input.
 (Yellow lines   )
  
 If I disconnect the wire from SG to the AC-inlet, the hum is still there.
  
  
 Input ground is isolated from the chassis (using neutrik jacks) and just
 conncted to the pot (and SG on the boards from there.)
  
 The output wiring is just temporary.
  
  
 Any idea where to start from?


----------



## muskyhuntr

Hi;
 I have 4 possible suggestions.  One of your RCA's is very close to one of your transformers.  You mention that one channel has a louder hum than the other.  Is that the channel?  Your on/off switch wiring runs very close to one of the amp boards.   Again, is that the channel with the loudest hum?  On mine, I used an IEC connector with a switch built in to avoid running AC wiring in what is a rather confined enclosure.  I can't really tell from your photo, but you also might try running a ground wire from one of the screws on your volume pot to ground.  Seems that a number of people had issues with the pot causing hum. Lastly, I ran all my circuit board grounds through a ground loop breaker and then to chassis ground.  Mains ground is attached directly to the chassis.
  
 My build had a very faint hum on both channels with one being slightly louder than the other.  Turned out to be a ground loop problem. 
 Hope this helps and good luck!
 Jim


----------



## stixx

Muskyhuntr beat me to it with his suggestions... 
I had the same thought about the proximity of the RCA and especially the wire from the IEC inlet to the switch...
try carefully wiggeling that wire around and see whether something changes.

My EHHA RevA is still on the breadboard but exhibits zero hum... and my wiring is less than perfect on a breadboard.

BTW... this is going to be a beauty!


----------



## Sathimas

I have 4 possible suggestions. One of your RCA's is very close to one of your transformers. You mention that one channel has a louder hum than the other. Is that the channel? 

- The two left RCAs are not connected at the moment, they're supposed to be the preamp outputs.
- Can't be the cause of the hum at the moment

 Your on/off switch wiring runs very close to one of the amp boards. Again, is that the channel with the loudest hum? 

- yes, it is, I'll try if the hum goes away when I put the wires further away from the board.
- but still there's the hum (more quiet) on the other board

On mine, I used an IEC connector with a switch built in to avoid running AC wiring in what is a rather confined enclosure. 

- Having the switch on the backside would be very impractical. let's see...

I can't really tell from your photo, but you also might try running a ground wire from one of the screws on your volume pot to ground. 
Seems that a number of people had issues with the pot causing hum. 

- I'll try that too.

Lastly, I ran all my circuit board grounds through a ground loop breaker and then to chassis ground. Mains ground is attached directly to the chassis.


----------



## Sathimas

News from Germany:

Pot screw connected to (input-) ground:

- no difference

Used another power switch and put the ac wires out of the case,
as far away as possible:

- no difference

There's nothing more I can test today, gotta go to bed.


----------



## cfcubed

sathimas said:


> (edited) It plays music without any flaw - but I have a* very loud hum on the left*
> and *a more quiet (hum) on the right channel*.


 
 Hate to tell you this but I'd bet good money its the proximity of those transformers to the amp.  Especially with the low-level signal/tube socket extension wires (acting like antennas).
 Lots of examples of hum problems happening w/various DIY headamps when transformers are very close to amp channels.  Google & you will find them. 
  
 E.g. If the LEFT channel board is the LEFT one in the picture, see how those 2 transformers are "ganging" up on it?  Perhaps their overlapping electromagnetic fields are bathing the left channel & feeding your tube-extensions/antennas.  In less extreme cases, rotating the transformers to try to lessen hum is something to try.
  
 Switching to expensive, possibly larger shielded & encapsulated transformers could help some, as could mu metal shields perhaps BUT nothing works like physical distance.  It's why I transitioned to 2-box builds soon after (re-)starting audio DIY years ago.


----------



## stixx

cfcubed,

I absolutely respect your point about the proximity of the transformers to the circuit possibly causing the hum...but I also somehow doubt that it would result in the strong hum Sathimas describes. Those are quality toroid transformers and not a microwave oven generating a massive magnetic field (just taking this as an example  ). 

I have a hard time believing that two toroids would interact with the circuit/wiring that badly... when tons of other builds and commercial gear exhibit the same proximity of the transformer/s. Even in DAC's it is very common to have the toroid right on the board, and there we are much more into RF/HF territory than in a headphone amplifier. 
I looked up a few random images of audio equipment with toroidal transformers (including my own EHHA, a Lehmann Black Cube, Stella DAC etc.), and while for some reason I don't get the option to attach the images here at my workstation (Java??) they all show the transformer sitting close to the amplifier section or even digital section! Of course I might be wrong, but I still suspect another cause of the hum problem.

Sathimas, how are your tube heater psu’s grounded?


----------



## cfcubed

stixx said:


> I absolutely respect your point about the proximity of the transformers to the circuit possibly causing the hum...but I also somehow doubt that it would result in the strong hum Sathimas describes. Those are quality toroid transformers and not a microwave oven generating a massive magnetic field (just taking this as an example
> 
> 
> 
> ...


 
  
 OK, I'll bud out.  What you say about commercial gear is spot on.  My post was more anecdotal based on my own experiences (CK²III, β22s & my EHHA) & those of others that have posted fairly frequently, e.g.:
http://www.head-fi.org/t/406258/mistakes-you-made-with-your-22-or-22/15
 And I don't see how your suggestions + review of his build picture otherwise explain the large difference in hum heard between his left & right channels.
 Also, I've found it fun to listen to hum level differences in my DIY amps on the bench as I move/rotate their (unshielded, non-encapsulated) toroidal transformers about them.  Esp. noticeable w/high-sensitivity cans.
 But carry on, I really need to stop posting here


----------



## Sathimas

Tube heater ps are wired directly to star ground, as you see in the picture.
(Yellow lines mark ground wires)

I'll try getting the torroids further away with some improvised cable extensions anyway.
Getting a custom wound encapsulated torroid also wouldn't be that expensive.

Main Problem is size...
And having the torroid in an extra place would require a new power inlet in the back.

But - we'll see.


----------



## funch

Is earth ground tied to the chassis? If not, you might try that. Also look into a ground loop breaker.


----------



## stixx

'But carry on, I really need to stop posting here'

No need to get upset, I didn't say that your suggestions were wrong. You have your findings based on your experience building gear, and so do I. And in about 15 headphone amplifier, chip amp and DAC builds I never had to deal with even the faintest of hums (but one--> see my first post here), despite the transformer being close to the circuit.
Again, in this special case I might be wrong.


----------



## jdkJake

I would also recommend you try the alternate wiring scheme for the signal ground as outlined on Alex's site. 

I personally had better success with the alternate wiring scheme.


----------



## Sathimas

> Is earth ground tied to the chassis? If not, you might try that.


 
  
 Earth ground is tied to the star ground - which is of cause connected to the
 bottom of the case, since the screw goes through.
  
  
 I just tried varying the distance of the torroids.
 Had the heater-torroid behind the back panel and the other one standing
 upright to the back. Even moved them closer and back off while listening.
 No audible change ...
  
 Going to try the alternate wiring now.
 Connecting all those tube-socket wires is a pain in the ***


----------



## Sathimas

Let's go on with the one man show 
 Think you're all sleeping in other time zones 
  
  
 Alternate wiring gave me a huge step forward.
  
  
 Only a faint hum is left - _now equally loud on both channels_.
  
  
 Just now I'm listening to the first tunes of Master of Puppets from the S&M Album
 with my ATH W1000. As soon as music is playing, I can't detect any disturbing noise.
  
 Yet it's there - might an ground loop breaker solve that problem?
  
  
 Another problem is that the amp happily picks up noise from my computer.
 At the moment the source is my gamma1dac. I still have to try out some other
 place for it, next to the external harddrive seems not that good :-D
  
  
 I'm also happy having the gain at 5, 8 would have been to high.
 (Just using high-efficiency cans as the ATH, Beyerdynamic T90, DT1350)
  
  
 And - by the way - sound is great, as expected 
	

	
	
		
		

		
			




  
  
 Thanks to everyone helping me here, and especially to Alex, for sharing this
 great amp design with the DIY-community.


----------



## jdkJake

sathimas said:


> Alternate wiring gave me a huge step forward.
> 
> 
> Only a faint hum is left - _now equally loud on both channels_.
> ...




I would advise you first verify the hum is not internally generated before moving outwards. 

Be advised, I would NOT use your good headphones for ANY initial testing. There are plenty of cheap, disposable headphones on the market for this task.

First, ground the inputs. I like to use a pair of shorted jacks (ground and signal connected), dressed with a piece of heat shrink.




Then, using your initial test headphones, see if you still hear a hum. Start with the signal fully attenuated and work your way up. Ideally, everything should be very much hum free. If there is hum, then something internally is amiss or some internal component is picking up on some external component inducing the hum.

After this step you can start to add external components and consider the use of a ground loop breaker.


----------



## Sathimas

I used some cheap earbuds for initial testing, no need to worry. 

I'll try what you suggested later this evening.


----------



## Sathimas

The hum is still there with grounded inputs, but not changing with volume.


----------



## Sathimas

Thought about the CLB now.
  
 I also found some other thread here in the forum about that.
 (Also read some facts on AMBs website.)
  
 Here's what I think I should do:

  
  
 Red are the ground wires, all connected to star ground, which is tied to earth ground.
 Yellow is input-ground.
  
  
 Are my thoughts correct?


----------



## stixx

Your image is really tiny this time... hard to decipher anything


----------



## Sathimas

Image is 2000px wide - just click on it


----------



## muskyhuntr

Hi,
 A couple more suggestions.
  
 1) Look on page 101 of this thread and you will see some pictures of my build.  Note that I have only 2 wires going to a "star ground" (from SG on the input connector) and those 2 are going through a ground loop breaker before going to chassis ground..  Mains ground is tied directly to the chassis. Your build has 7 wires.  All these are possible points to inject hum into your project..  My only complaint with this amp is that there is too much external wiring to the board.
 2) The left 2 RCA's on your build are wired to ground, though the positives are not wired.  Try disconnecting those for the time being.
 3) Take one channel out of the equation.  Disconnect every thing related to that channel. Trouble shoot just one channel at a time.  Make sure nothing from that channel is connected. Start from the beginning.    Remove all the major possibilities out of the case (transformers, switch wiring, etc).  Remove all your ground wiring and then re attach one at a time and in different combinations.  Are you twisting your wires?  If you are trouble shooting without a source, follow jdkJake's suggestion and short your inputs.  Have you tried swapping the tubes to see if louder hum moves with the change?  Once you solve the problem on one channel, work on the other.
 4) On your next build, mount everything on a piece of plywood and trouble shoot from there.  You can see where Stixx and I did this earlier in the thread.
  
 Keep at it, this amp is worth it!
 Jim


----------



## stixx

"Image is 2000px wide - just click on it "

Really strange... I did click it... still tiny. Guess my computer here at work is blocking something


----------



## Sathimas

> Hi,
> A couple more suggestions.
> 
> 1) Look on page 101 of this thread and you will see some pictures of my build.  Note that I have only 2 wires going to a "star ground" (from SG on the input connector) and those 2 are going through a ground loop breaker before going to chassis ground..  Mains ground is tied directly to the chassis. Your build has 7 wires.  All these are possible points to inject hum into your project..  My only complaint with this amp is that there is too much external wiring to the board.


 
  
 Let's clarify some vocabulary first, since all those different "grounds" confuse me:
  
 Mains Ground
 Earth ground
 Chassis Ground
 Star Ground
  
 I think mains ground = earth ground on IEC
  
 Chassis ground = connection to metal bottom of the case.
 Im my case, star ground is connected to chassis ground.
  
 Where did you connect the grounds of the heater and amp power supplies
 if you have only wired the SG-points on the amp boards?
 (I can't make it out on the pictures)
  
 Ground of power supply and amp board seems directly wired,
 I routed those wires to star ground and back, according to the scheme
 on the website.
  


> 2) The left 2 RCA's on your build are wired to ground, though the positives are not wired.  Try disconnecting those for the time being.


 
  
 I'll try - but I'll need them as soon as I have the e12 here.
  


> 3) Take one channel out of the equation.  Disconnect every thing related to that channel. Trouble shoot just one channel at a time.  Make sure nothing from that channel is connected. Start from the beginning.    Remove all the major possibilities out of the case (transformers, switch wiring, etc).  Remove all your ground wiring and then re attach one at a time and in different combinations.  Are you twisting your wires?  If you are trouble shooting without a source, follow jdkJake's suggestion and short your inputs.  Have you tried swapping the tubes to see if louder hum moves with the change?  Once you solve the problem on one channel, work on the other.


 
  
 1. wires from the 30V torroid are braided, those from the 9V are not.
 Input wiring is fully shielded
 2. Tubes don't make a difference. As I said before, there's no difference betwenn
 the channels anymore since I use the alternate wiring scheme.
  


> 4) On your next build, mount everything on a piece of plywood and trouble shoot from there.  You can see where Stixx and I did this earlier in the thread.


 
  
 Did this with the amps before this one, but since I never had
 those problems before I was kind of too optimistic here.


> Keep at it, this amp is worth it!
> Jim


 
  
 I definitley will!


----------



## UKToecutter

Whilst I hope I won't be shot down in flames.....
  
 I believe SG is Signal Ground.
 Star Ground is the designator of the topology where grounds are 'tied' together at a single point to ensure there is no potential difference between any of the grounds.


----------



## stixx

> I believe SG is Signal Ground. Star Ground is the designator of the topology where grounds are 'tied' together at a single point to ensure there is no potential difference between any of the grounds.


 
 Correct.


----------



## stixx

...and another point just crosses my mind looking at the last pic... (now big 
	

	
	
		
		

		
			





).
 Isn't the GLB supposed to be put between chassis and Mains Ground?
 Not sure since I never used one...


----------



## muskyhuntr

Hi All;
  
 Your mains ground should be connected to earth, thus, for this conversation, they are about the same thing.  Your mains ground should then be connected directly to the chassis. Star ground is a common point for grounding as UKToecutter points out.  This common point may be tied directly to chassis ground or "lifted" through a ground loop breaker.  Meaning all the wires are connected at a common point, run through the breaker (there are several types) and then to the chassis.
 My heater and power supply lines are connected directly to the amp board with twisted pairs.  Ground lines are not routed to star ground first.
 The only common point or star ground I used was to run 1 wire from SG on each board (located on the input connector) to my ground loop breaker and from there to chassis ground.  SG probably means signal ground in relation to this connector.
  
 Stixx asked "Isn't the GLB supposed to be put between chassis and Mains Ground?"  I have seen people posting builds done both ways. On this one, I use it between the amp boards and chassis. I don't like the idea of directly connecting any of my electronics to a wire that plugs into the wall.
  
 One tip I read in a post a year or so ago was to construct a GLB with a longish pigtail wire attached.  Connect one end to chassis ground and use the pigtail to "probe" different grounding spots while listening for a reduction in noise.  This is how I traced down my problem.
  
 I hope this helps.
 Jim


----------



## muskyhuntr

Hi All;
  
 Your mains ground should be connected to earth, thus, for this conversation, they are about the same thing.  Your mains ground should be connected directly to the chassis. Star ground is a common point for grounding as UKToecutter points out.  This common point may be tied directly to chassis ground or "lifted" through a ground loop breaker.  Meaning all the wires are connected at a common point, run through the breaker (there are several types) and then to the chassis.
 My heater and power supply lines are connected directly to the amp board.  Ground lines are not routed to star ground first.
 The only common point or star ground I used was to run 1 wire from SG on each board (located on the input connector) to my ground loop breaker and from there to chassis ground.  SG probably means signal ground in relation to this connector.
  
 Stixx asked "Isn't the GLB supposed to be put between chassis and Mains Ground?"  I have seen people posting builds done both ways. On this one, I use it between the amp boards and chassis. I don't like the idea of directly connecting any of my electronics to a wire that plugs into the wall.
  
 One tip I read in a post a year or so ago was to construct a GLB with a longish pigtail wire attached.  Connect one end to chassis ground and use the pigtail to "probe" different grounding spots while listening for a reduction in noise.  This is how I traced down my problem.
  
 I hope this helps.
 Jim


----------



## Sathimas

Ok, I will now start to test.
  
 For the first point, I directly wired ground of amp ps and amp board.
 Since the ground wires coming from the ps are soldered below the
 board I just left them floating. (Dismounting the boards is a huge effort...)
  
 That actually brought me back to the state before.
 Loud hum on the left channel and more quiet on the right. 
	

	
	
		
		

		
		
	


	



  
 When I attach the ground of the left amp PS to star ground, the hum
 gets a bit more quiet.
  
 muskyhuntr:
As far as I see in the Pictures, your heater-ps grounds are not connected to anything?


----------



## muskyhuntr

Hi All;
  
 You are right,  plus/minus from the power supplies to plus/minus on the amp boards. This goes for both the heater supply and the amp supply.
  
 Jim


----------



## Sathimas

But have you wired ground from the amp ps and ground of the amp board?
  
  
 I just reconnected amp ps ground to star ground and disconnected
 the heater ps ground from star ground:
  
 Gives me same hum on both channels, louder than with heater ps
 ground attached to star ground, but not as loud as the hum that
 comes on the left channel when amp ps ground is not connected to
 star ground, but to amp board ground.
  
 This is so damn confusing!


----------



## muskyhuntr

Hi All;
  
 The rail supply board has a connector with 3 outputs, +30, 0, -30.  With 0 considered as ground.  The amp board has a connector for 4 connections, +30, ground, out, and -30.  On mine, I have the +30 connected to the +30 on the amp board, the -30 connected to -30 on the amp board and the 0 connected to ground which is next to the +30 on the amp board.  Additionally, on the rail power supply board, I  have 2 wires connected to the +30 and the -30 going to the E12.  On the amp board I have 2 additional wires going from out and ground to my E12.  Each channel is wired the same.  As noted earlier, the EHHA requires 2 E12's because there are 2 power supplies.  The ground from each E12 is combined at the output jack.  The jack, BTW, is isolated from the chassis.  Nowhere are wires run from either the rail supply or the heater supply to a star ground. 
  
 Hope this helps
 Jim


----------



## stixx

> Nowhere are wires run from either the rail supply or the heater supply to a star ground.


 
 Sorry Jim,
 but isn't this misleading? When I look at my breadboard as well as on both wiring schemes there are wires from
 either heater supply and rail supply to Star Ground...


----------



## muskyhuntr

Hi All;
  
 From Stixx:  "Sorry Jim, but isn't this misleading? When I look at my breadboard as well as on both wiring schemes there are wires from
 either heater supply and rail supply to Star Ground..."
  
 You are right.  I was referring to my build in that statement and should have been more clear.  I probably should have stated this from the beginning that I did not follow Cavalli's wiring scheme.  My intention was to make the absolute minimum connections needed for operation (heater supply, rail supply, input, and output) and then, if there was a hum problem, go from there.  My one criticism of this amp is that there are too many connections to and from the boards.  I wanted to eliminate as many as possible.  I was lucky in that I only needed the two from SG.
  
 I'm sorry if I was misleading, I hope this clears it up. 
  
 Jim


----------



## stixx

Having a go at this again...

I had a close look at your first image (post # 1552) and it seems correct to me, except that the pot
is not connected. Both channels of the pot have to be connected with their ground pins to ground 
or there will be hum!

You seem to have wired all psu grounds and heater grounds to star ground. Amp board and psu 
board are connected. RCA's (isolated) and the pot are connected to Star Ground as well as the 
output jack. Doing so should result in no hum...?

I did exactly so on my breadboard. As Jim pointed out you can “lift” the Ground via a Ground Loop
Breaker that goes between your Star Point and Earth (at the IEC connector).

Have you checked the pot? Both channels connected to star ground…? (my last hope)


----------



## proid

I was wondering if i could use 12au7?  The plate voltage is limited to 30V only but there are good souding amp like project sunrise only run at 13.5V plate


----------



## jdkJake

muskyhuntr said:


> Hi All;
> 
> The rail supply board has a connector with 3 outputs, +30, 0, -30.  With 0 considered as ground.  The amp board has a connector for 4 connections, +30, ground, out, and -30.  On mine, I have the +30 connected to the +30 on the amp board, the -30 connected to -30 on the amp board and the 0 connected to ground which is next to the +30 on the amp board.  Additionally, on the rail power supply board, I  have 2 wires connected to the +30 and the -30 going to the E12.  On the amp board I have 2 additional wires going from out and ground to my E12.  Each channel is wired the same.  As noted earlier, the EHHA requires 2 E12's because there are 2 power supplies.  The ground from each E12 is combined at the output jack.  The jack, BTW, is isolated from the chassis.  Nowhere are wires run from either the rail supply or the heater supply to a star ground.
> 
> ...




You connected the center tap of your transformer to what ground???


----------



## jdkJake

sathimas said:


> But have you wired ground from the amp ps and ground of the amp board?
> 
> 
> I just reconnected amp ps ground to star ground and disconnected
> ...




You are not the only one confused. 

Did you follow the alternate grounding scheme or not?

Follow the alternate grounding scheme and establish a reference. In this configuration, which channel exhibits a hum?


----------



## muskyhuntr

Hi All;
  
 jdkJake asks: "You connected the center tap of your transformer to what ground???"
 Nowhere in any posting have I even suggested that I connected the center tap of my transformer to any ground connection.
  
 Jim
 Sathimus you have mail


----------



## Sathimas

to get things a bit more clear:
  
 At the moment, my amp is wired exactly as cavalli shows  for the "alternate wiring scheme".
  
  
 Today the parts for the GLB arrived.
  
  
  


> I had a close look at your first image (post # 1552) and it seems correct to me, except that the pot
> is not connected. Both channels of the pot have to be connected with their ground pins to ground
> or there will be hum!


 
  
 The two ground-pins of the pot are connected with a piece of wired, bridged, so to say.
 The ground of the input jacks is also wired to those pins, as well as each "IG" is connected.

  


> You seem to have wired all psu grounds and heater grounds to star ground.


 
  
 Yes
  


> Amp board and psu board are connected.


 
Yes
  


> RCA's (isolated) and the pot are connected to Star Ground as well as the
> output jack. Doing so should result in no hum...?


 
 Output jack is connected to star ground.
  
 Ground of the RCAs (which is wired to the pots ground pins) is only connected
to "IG", not to star ground.
  
May that be the problem?


----------



## stixx

> Ground of the RCAs (which is wired to the pots ground pins) is only connected
> to "IG", not to star ground.


 
 No, that shouldn't be a problem... According to the wiring scheme that is your Input Ground (IG) which is grounded to the Star through the board.
 I usually wire the RCA's and the pot (and sometimes the output jack) as a sub-group that is then connected to the Star Ground. Just make sure
 none of your components has two connections to the Star or you will have a Ground Loop.
  
 Tricky thing you have there...


----------



## jdkJake

At this point, I think you need to consider isolating each channel separately and see if you can narrow things down a bit.

By that, I mean electronically disconnect one channel and see if both channels exhibit the hum independently. Even if they do, it should be easier, at least in theory, to isolate what may be causing the hum.


----------



## Sathimas

First, some more precise discription of the 2disturbing nioses:
  
 1. hum
 quiet, just hearable - not disturbing anymore when music is playing.
 equally loud on both channels, even there with grounded inputs and not changing
 with the volume
  
 2. crackling, hissing sounds
 louder than the hum and increasing with volume
  
  
  
 Some update on my results:
  
 What I tried up 'til now:
  
 1. alternate wiring scheme, but having the GLB between Starground and mains ground
  
 - no effect
  
 2. alternate wiring scheme, with GLB between star- and mainsground, but having starground
 floating and not connected to chassis
  
 - no effect
  
 3. ground of amp ps and amp directly connected, ground of heater ps not connected
 just SG connected to starground, GLB between star- and mainsground
  
 - loud hum on left channel, quiet hum (just like before) on the right
  
  
 No I'll go on and check the channels one by one.


----------



## Sathimas

*right *channel only, all wires disconnected from the left one
  
 Inputs are *open*
  
 1. 
 ground of amp ps and amp directly connected, ground of heater ps not connected
 just SG connected to starground, GLB between star- and mainsground
  
 - no effect, still having the subtle hum
  
 2. 
 ground of amp ps and amp directly connected, ground of heater ps and 
 SG connected to starground, GLB between star- and mainsground
  
 - no noticalbe hum, hum only comes up when I turn up the volume a lot,
 much more than I ever would when listening to music
  
 - this is the *first *really positive result
  
 no further tests, since the right channel is working as it should now
  
  
 Let's move on to the *left *one, same as before, right channel completely disconnected
  
  
 1.
 ground of amp ps and amp directly connected, ground of heater ps and 
 SG connected to starground, GLB between star- and mainsground
  
 - same as left channel! 
_- no noticalbe hum, hum only comes up when I turn up the volume a lot,_
_much more than I ever would when listening to music_
  
  
 So, let's hook up both channels this way and see what happens:
  
 1. - both channels
 ground of amp ps and amp directly connected, ground of heater ps and 
 SG connected to starground, GLB between star- and mainsground
  
 - *loud *hum on the left, more quiet, but noticable hum on the right
  
  
  
 Does this give one you a clou how to solve that problem?


----------



## fishski13

maybe we don't need another cook in the kitchen...

-when you say that the inputs are "open", do you mean that they are NOT shorted to input ground? i would make sure that they are shorted to input ground to rule out that the input wiring from RCA to pot and pot to board inputs is not picking up noise, and that it's the amp itself generating the noise. the input wiring is a high impedance circuit and prone to noise. IME, shielding the input wiring isn't effective for EMI, only RFI. also, make sure the shields are tied to signal/input ground and not chassis ground. 

-i see the GLB breaker as been disscused in detail. just make surre all ground points connect to one side of the GLB and the other side of the GLB to chassis ground. not that i think a GLB is your problem.

i had an EHHA here for a rebuild and new chassis. it was basically dead quiet when i received it. when i put it in a larger chassis, with cleaner layout and wiring, i got noise in only one channel. i ended up flipping boards around and routing the wire under the boards a little differently and the noise went away. i don't know if you've tried this, but "chop-sticking"/moving exposed wires can be beneficial in sleuthing out noise as well, especially with input wiring.


----------



## newbienewbie

Hi guys,
  
 just today I've managed to resurrect this build from the attic where
 it stood for more than half a year. Anyway I've completed all the wiring
 hooked it up to a CD player as source and - no sound. Dead quiet nothingness.
 No hum no buzz no noise. All the test diodes are lit. I've measured the output
 accross the testpoints on the boad and I get about 210mv (the same for both channels),
 which is in line with the instructions. Any hints about where I might start the debugging process?
 Everything looks ok, soldering seems to have been done ok, no parts look burnt or blown...
  
 I'd appreciate a nudge in the right direction.


----------



## newbienewbie

Hey,
  
 please just disregard the post above. It turned out to be an issue with the volume pot.
 Problem solved.


----------



## jdkJake

sathimas said:


> *right* channel only, all wires disconnected from the left one
> 
> Inputs are *open*
> 
> ...




Interesting.

Do you have the left and right signal grounds tied together at the inputs? If not, are they tied together at the pot?


----------



## Sathimas

> -when you say that the inputs are "open", do you mean that they are NOT shorted to input ground? i would make sure that they are shorted to input ground to rule out that the input wiring from RCA to pot and pot to board inputs is not picking up noise, and that it's the amp itself generating the noise.


 
  
 Inputs were not grounded - but even with *open *inputs each channel for itself was quiet.
  
When I have both channels operating the loud hum on the left is there
_with _and _without_ grounded inputs - so the hum must be coming from the amp itself.
  


> Do you have the left and right signal grounds tied together at the inputs? If not, are they tied together at the pot?


 
  
 Input ground wiring:
  
 All 4 input groundconncectors are connected in line
 From there input ground is wired to the pot (ground pins of the pot
 connected as well) From the pot input ground is wired to IG on the board.


----------



## Sathimas

Some more experimenting (inputs grounded)
  
 Changes:
  
 1. headphone-jack ground wired to both groundconnectors on the amp boards
  
 - less (next to no) hum on the right, small decrease in hum volume on the left, but still loud
  
 2. Trying asymmetrical wiring: (leaving jack-gr connected to amp-gr)
  
 - right channel - ps-gr tied to amp-gr
 - left channel - ps-gr tied to star-gr
  
 -> *no *hum on the right, even when turning up the volume very high
 -> slight hum on the left, but still noticable (not changing with volume)
  
 We'll  - I'm getting closer !
  
  
 The hissing/buzzing is also gone when connected to my y1-DAC.


----------



## fishski13

just for clarity, what i mean by "inputs shorted" is: the pot not connected to amp boards and each input pad connected to input ground on each board connected with a wire lead snipping or wire. if the pot is connected, you have not isolated the pot as the problem.

i'm not sure if you're doing this, but keep all grounds from each channel completely separate up to the GLB/star ground. i.e. L/R channel grounds only meet at one point at the star ground.


----------



## jdkJake

sathimas said:


> Input ground wiring:
> 
> All 4 input groundconncectors are connected in line
> From there input ground is wired to the pot (ground pins of the pot
> connected as well) From the pot input ground is wired to IG on the board.




I think you should do what fishski13 is recommending and take the entire input section, including the pot, out of the equation and see where things lie.

I am a fan of wiring input signal grounds to the pot sperately and maintaining them separately all the way into the input(s) of the amp boards. I think you should separate those input grounds after you try what fishski13 recommends to see if the input section is the cause of the problem. His recommended test is straightforward and should answer a few concerns I see with your input wiring.


----------



## Sathimas

Inputs were grounded at the input jacks.
  
 I'll try your suggestions tomorrow and see what happens.


----------



## fishski13

Noise is really frustrating, especially after you spent all the work you put into the chassis and layout. I think you're really close.

As Jake said, i too prefer to keep the L/R grounds separate from input RCAs through the pot and to the boards. With star grounding, it's best to keep the channel grounds separate from one another up to the chassis star ground.


----------



## Sathimas

Took a bit longer than I thought ...
  
 With the inputs grounded directly on the boards there's no hum on the right
 and more hum on the left than with the pot connected.
  
 I'll try separate input ground wiring now.
  
  
 Btw: With my 250Ohm T90 the amp is dead quiet


----------



## Sathimas

Next results:
  
 I wired input ground from the jack to the pot separately for each channel.
 Ground pins on the pot are not connected to each other.
  
 Result is the same as with inputs grounded directly at the board:
  
 Worse than having everything hooked up like before....


----------



## jdkJake

sathimas said:


> Took a bit longer than I thought ...
> 
> With the inputs grounded directly on the boards there's no hum on the right
> and more hum on the left than with the pot connected.
> ...




Okay. At least you are down to one board. Since the right one is fine, it is just a matter of tracking down the difference between the two.

I would verify your ground connections on the screw headers are making contact properly (no cold soldier joints, etc...). Using a multimeter, can you verify the star ground connection on the input header is making contact with the ground plane? You can measure between that point and any other ground point. Or, you can use O3 on the output header as long as it is not wired up (disconnect temporarily).

You may also want to swap the left and right channels and see if the problem follows the board. That would help rule out chassis wiring and isolate the problem to the amp board itself.

BTW, What are you using for output resistors? (R22/R23) Did you build the MOSFET or BJT?


----------



## fishski13

good points. i would take out fhe boards, swap them, and double check all wiring. if the noise follows the board, then it's the PCB - maybe even a cold solder joint on one of the Phoenix connectors that broke loose with the force of tightening the wire in with a screwdriver. also, pay attention to Phoenix header/slots that have more than one wire. i prefer to only use one terminal wire per slot. if you need to connect two wires, just solder the 2nd wire just up stream and use some heatshrink if necessary.


----------



## Sathimas

Well, I'll try - but maybe I cant swap the boards because of the tube-socket wiring...


----------



## Sathimas

I built the mosfet version from the kit of glass jar audio.
  
 Do you want to know the values of the resistors?
 Can't find the glassjaraudio bom at the moment and
 the multimeter is dead because of an empty battery.
 (Gonna get a new one tomorrow)


----------



## jdkJake

sathimas said:


> I built the mosfet version from the kit of glass jar audio.
> 
> Do you want to know the values of the resistors?




Yes. 

BTW, did you ever swap the tubes between the two channels to see if the problem is with one of the tubes?


----------



## stixx

I seem to remember that Sathimas did swap the tubes as one of his first attempts to track down the cause of the hum...


----------



## Sathimas

Swapping the tubes brings no change, hum stays left.
  
  
 What confuses me most is that each channel alone, with the other
 one being not connected, is quiet. Only having them both running
 brings up the hum.
  
 Here's the resistor-values: 2.2 Ohm
  


> I would verify your ground connections on the screw headers are making contact properly (no cold soldier joints, etc...)


 
  
 Did that already to be sure - got 0 ohms from all ground connectors to star ground.


----------



## Sathimas

Some more experimenting:
  
 Swapped the boards, both wired that way:
 (The configuration in which channel alone is quiet)
  
 Output ground - output jack
  
 amp_ps ground - ground on amp board
  
 heater_ps ground - star ground
  
 SG on amp board - star ground
  
  
 GLB between SG and mains ground on the AC-inlet
  
   





> The hum is still on the left side after swapping the channels.
> So the "left" board is not the problem.


 
 Well, this conlusion seems wrong or at least not complete...
  
  
 Having everything wired like the "alternate wiring scheme",
 now the right channel exhibits the hum. (The board that was left before...)
  
 This is really crazy.
  
  
 [Edit Nr.2]
  
 Having all wired after the normal wiring scheme the hum stays right.


----------



## Sathimas

Took out the probably faulty channel once again and carefully reflowed all solder joints.
  
 Back in the case, wired after the alternate wiring scheme  I now have the same
 subtle hum on both channels - wooohoooo!
  
  
 With my ATH W1000, it is barely noticable without music playing.
 With the Beyer DT1350 it's the same - barely there, but still there...
  
  
 I'll try out some other wiring options now - having some new hope now...
  
  
 [Edit]
  
 Transplanted everything back (re-swapping channels), tidied up the wiring
 and there was *no* bad surprise after switching on the amp


----------



## stixx

Hang on in Sathimas, you are almost there...!
  
 Your head must be buzzing from all that rewiring, checking and test-listening  
	

	
	
		
		

		
			





.


----------



## Sathimas

My head is indeed buzzing :-D
  
  
 For the moment I'll settle with what I have accomplished 'til now.
  
  
 I really gotta concentrate to hear the hum on the left.
 On my right ear I can't hear it anyway since I got a 40dB hearing loss
 up to 1Khz - maybe the only benefit of that screw*** acute hearing loss... 
  
  
 Now I'll wait until I get the AMB e12 and see what happens after
 adding that to the circuit.
  
  
 Next step is cutting a piece of acryl glass that will hold the pot.
  
  
 Thankfully, a friend of mine has already done some tests on that:
  
http://eigenbaukombinat.de/bastlerglas-frasen-versuch-nr-3-4-und-5/


----------



## FOXY

Anyone using ehha with HD800?


----------



## Mullet

foxy said:


> Anyone using ehha with HD800?


 
  
 I've been curious about this as well. Don't have them, but I could see getting them in the future.
  
 Anyone know if Jeff Rossel at Glass Jar Audio is away on vacation or still selling kits? I've emailed twice and haven't gotten a response. Maybe, I'm just being a little impatient.


----------



## tomb

mullet said:


> foxy said:
> 
> 
> > Anyone using ehha with HD800?
> ...


 

 Yes, maybe you are.
	

	
	
		
		

		
			





   He must be super-busy, as usual.  I've just completed a small deal with him over the weekend.  So, I know for a fact he is alive, well, and pursuing business as usual.


----------



## stixx

> Anyone using ehha with HD800?


 
 Though my EHHA RevA is still on the breadboard (... and will remain there for a while because of too many other projects...) I have tried it with my HD800's.
 Works very well with a balanced sound, quite tight bass and, most important, natural highs! The EHHA doesn't have the upper midrange glare of some solid state amps so does very well with the sonic character of the HD800.
  
 Btw. anybody wanting to tame the slight treble peak of the HD800 try the so called *Anax mod*... there is a very nice write up with extensive measurements on Innerfidelity.com!


----------



## Fred_com

Hi guys,
  
 does anyone know what is the input impedance of EHHA rev A?
  
 I've tried searching this thread, but found nothing.
  
 Thanks,
 Fedor


----------



## tomb

fred_com said:


> Hi guys,
> 
> does anyone know what is the input impedance of EHHA rev A?
> 
> ...


 

 Not my thread, but for any amp that has the volume pot at the input (everything ever designed except the O2) - it's the impedance of the volume pot.


----------



## Fred_com

Hi tomb,
  
 thank you for the answer.
  
 What if there is no volume pot? Could we say that input impedance will be equal to resistor which is connected to ground at the input (grid leak resistor?, which is 1M in EHHA), if such resistor exists?


----------



## Sathimas

Today I finally managed to put in the e12.
  
 Wired OG seperately from each board to the e12 and from there
 to the headphonejack - tying them together there.
  
 Now again, there's a slight hum ... (where the amp was quiet before.)
  
 At the moment I'm experimenting with the wire routing, we'll see


----------



## satwilson

I read a post over on DIYAUDIO that suggested a 5751 tube as a possible substitute for the 6GM8. Any thoughts on this?


----------



## stixx

> I read a post over on DIYAUDIO that suggested a 5751 tube as a possible substitute for the 6GM8. Any thoughts on this?


 
  
 Looking at the data of the 5751 tube it appears to be a replacement for 12AX7/ECC83 but not 6GM8... plate voltage is much higher and so is gain (70 vs 14).
 I haven't bothered to check the pin-out. A real substitute would be ECC86...


----------



## Sathimas

hi there, I'm back - and still having noise problems.
  
 Good news is that I finally found out where (at least a part of) the hum came from.
  
  
 Here's a picture of the now final interior of the case:

  
 I shifted the AC wires from the 30-0-30 torroid a bit and the hum was much less - crazy.
  
  
 Now there's still some kind of buzzing noise, higher pitched than the usual 50Hz hum.
 Apart from that, there's no hum or noise even with open inputs and fully open pot.
  
 I'm doing some testing at the moment since the noise is extremely sensitive
 to how the wires from the torroid are routed...
  
 ______________________________________
  
 Tried several variants now, gave some more twist to the already braided wires...
 Tried alternate and normal grounding scheme again, also asymetrical.
  
 No change, except that hum and buzz are changing a bit depending on how
 I arrange them at their origin at the torroid.
  
 Now I found that I can actually "feel" the torroid, I clearly feel it's vibrations.
  
 Maybe I have to get another torroid?
  
  
 This amp is driving me crazy.


----------



## stixx

I am afraid I can't help much except for saying you should have gotten the toroids from Rondo... no vibration issues whatsoever 
	

	
	
		
		

		
		
	


	



 Have you mounted them on rubber discs (or cut some from 5-8mm Moosgummi)?


----------



## Ishcabible

Hi! I have one of these, but it's killed the right driver of two of my headphones. Does anyone know what could potentially be the problem?


----------



## Sathimas

I just took the avel lindberg torroids because they came with the kit and never made problems before in my other builds.
 Think I'll get some new ones from rondo now.
  
 What size are your's stixx?
  
  


> Hi! I have one of these, but it's killed the right driver of two of my headphones. Does anyone know what could potentially be the problem?


 
  
 High DC-offset at amp startup - have you ever measured that?


----------



## stixx

> What size are your's stixx?


 
 They are 40VA... in my case 2x27V /0.65A and 1x7V for the heaters...
 Good luck... you are almost there!


----------



## Sathimas

I meant physical size, since I dont habe much room.


----------



## stixx

Sorry, of course.
  
 They are 87mm dia. and 42mm high.


----------



## Ishcabible

sathimas said:


> High DC-offset at amp startup - have you ever measured that?


 
  
 Sorry, I just got time to remeasure it! It's 1.5mV, and it's never done anything at start up, but randomly.


----------



## Mullet

So I'm in the process of finally building up my EHHA Rev A. It's been a long time coming. A few questions...
  
 I plan on adding sockets for the gain resistors. Is it safe to say that R10 doesn't need to be socketed. I'm thinking that R11, R13, and R14 are what would be changed anyway.
  
 For power management, I'm thinking two 4 position wire-to-wire terminals would be appropriate. One for IEC socket to both trafos. The other for 30-0-30 power management. I'm thinking it might not be necessary for the heater trafo though. Then I'd get another 4 pos. barrier terminal for SG management.
  
 The only other thing that I can think of right now is how to wire up the 2 E12s. I know about the ±30v. I'm assuming the Left channel goes to L+ on one E12 and the Right channel goes to R+ on the other E12. But what about SG connections? I'm not quite there yet in terms of having the build ready, but want to have it figured out fairly soon.


----------



## proid

I was wondering can i change the transistor in the servo booster from C2705/A1145 to BC546/556? I use spice to simulate and it's working fine but in real world performance  do you guy think it will affect the sound quality?


----------



## gurubhai

proid said:


> I was wondering can i change the transistor in the servo booster from C2705/A1145 to BC546/556? I use spice to simulate and it's working fine but in real world performance  do you guy think it will affect the sound quality?


 
 I used them in my original EHHA -1 and it worked fine. Its been a while so I can't remember the details but at that time I felt that the one with Toshiba devices sounded slightly cleaner(not much of a difference though).
 P.S. - Don't forget to twist the legs of BC devices to match the pin orientation.


----------



## proid

gurubhai said:


> I used them in my original EHHA -1 and it worked fine. Its been a while so I can't remember the details but at that time I felt that the one with Toshiba devices sounded slightly cleaner(not much of a difference though).
> P.S. - Don't forget to twist the legs of BC devices to match the pin orientation.


 
 Thanks for you helpful comment, so you did change not only the servo booster but all the transistor to BC546/556?


----------



## Mullet

So no one has answers to my questions...
  
 I'm going to guess that I don't have to socket R10. Looks like it will always be stationary. So scratch that one off. Power management wise... I'm sure I'll just wing it and see if what I bought was the right parts for the job.
 The E12s are where I'm still not sure of proper wiring. I'll have to reach out to Amb's forum and inquire there.


----------



## gurubhai

proid said:


> Thanks for you helpful comment, so you did change not only the servo booster but all the transistor to BC546/556?


 
 Ahh, didn't notice that you were enquiring only about the servo, I doubt that changing that would have any effect on sound.I had used only the BC devices in that particular amp, since I didn't have the Toshiba transistors at hand at that point of time.


----------



## proid

I have finished my EHHA RevA, both channel sound fine but it has very annoying noise like a sine wave at 5khz, it increase a bit if i turn the volume up. Everything measure fine, my build using bc546/556 for the servo booster and the current source for tube like the EHHA 1 (because i don't have the CRD), 1145/2705 for the rest and i use a shunt regulator to power it. I use both the original wiring and alternative wiring but nothing change. The tube i'm currently using is 6h6n which is an equivalent to 6h30.


----------



## Mullet

Do you mean a 50 or 60hz hum? 5Khz would be a pretty high whine. Several posts mention to use a Ground Loop breaker to get rid of Gnd loop hum.
  
 Also, have you compensated for the higher heater current required for the 6H30? I know from EHHA I you needed to do this. Also, there was a trimpot required to use alternate tubes. I would use the 6GM8 first to test if it's a tube problem.


----------



## proid

mullet said:


> Do you mean a 50 or 60hz hum? 5Khz would be a pretty high whine. Several posts mention to use a Ground Loop breaker to get rid of Gnd loop hum.
> 
> Also, have you compensated for the higher heater current required for the 6H30? I know from EHHA I you needed to do this. Also, there was a trimpot required to use alternate tubes. I would use the 6GM8 first to test if it's a tube problem.


 

 No, it's not 60 or 120hz hump, it's like some one playing sine wave at some where between 4k-6khz. What do i need to compensate for higher heater current tube? My tube sound fine in another amp so the problem must come from the EHHA.  I currently haven't cased it up so i can't do the ground loop breaker.


----------



## Mullet

The tube requires more current to work properly. In the EHHA directions (not Rev A) on the Cavalli Audio site, it states that you need to compensate by providing more current on the heater supply. Also, there is mention of a trimpot that is used to balance the triodes. This is because you're running the tubes at a lower voltage than what they normally require and at a lower voltage the triode balance is off. I'd buy some 6GM8s or the Russian 6N27Ps, which are the 6GM8 equivalent. Plus, I'm not sure if there is a part equivalent to R6 on the Rev A, so how would you balance out the triodes.
  
 This is what the Cavalli sites says:
  
*6922, 6H30 and other compatible tubes*
  
 Tubes designed for higher operating voltages than the 6GM8 will tend to have more triode imbalance at low voltages. To compensate for this possibility install the trimpot R6. See the Instructions page for steps in making out of balance tubes work.
  
 Beware that the heater current for a single 6H30 is approximately 800mA. Increase the size of the heater transformer according.


----------



## proid

mullet said:


> The tube requires more current to work properly. In the EHHA directions (not Rev A) on the Cavalli Audio site, it states that you need to compensate by providing more current on the heater supply. Also, there is mention of a trimpot that is used to balance the triodes. This is because you're running the tubes at a lower voltage than what they normally require and at a lower voltage the triode balance is off. I'd buy some 6GM8s or the Russian 6N27Ps, which are the 6GM8 equivalent. Plus, I'm not sure if there is a part equivalent to R6 on the Rev A, so how would you balance out the triodes.
> 
> This is what the Cavalli sites says:
> 
> ...


 
  
 I use a 9V 2A transformer and the regulator is heatsinked well so that's not the problem. I wonder what will happen if the triode a not balance, can it make that noise? I don't have 6GM8 or 6n27p so i can only use 6h6n now.


----------



## stixx

> I wonder what will happen if the triode a not balance, can it make that noise? I don't have 6GM8 or 6n27p so i can only use 6h6n now.


 
 I guess 6H6N is the same as 6N6P... anyway this tube is usually biased at higher supply voltage (from 80V up). The important bit is: where is the 6N6P biased with the given parts in the EHHA RevA?
 Theoretically this could put the tube at a bias point it doesn't like, though I don't think it would produce a high pitched noise like you are describing... rather just higher distortion.
 Still worth checking.and I'll also advise to get some tubes the circuit was designed for (6N27P are still reasonably priced last time I checked... I am using them in my build).


----------



## cfcubed

It's silly but did you try moving the amp to a different location? Just to rule out interference from a nearby device.


----------



## Sathimas

Very basic electronics question:
  
 I got 2 new transformers (custom wound, two identical ones now with 9V and 30V each)
  
 Due to my unpreciseness in the order, I got them 2x12V instead of 12-0-12 center tapped.
  
 Now I tried to figure out how to connect them to the PS but got more confused the more I read ^^


----------



## stixx

Sathimas,
  
 your description does confuse me...
 Is it 9V for the heater supplies or 12V? 12 V would be way too high for 6.3V heaters... I am using a 7V winding btw.
 A regular 12V winding is 12-0, so you just hook it up to the heater supplies... 
	

	
	
		
		

		
			




 Or am I missing something?


----------



## Sathimas

Forget what I wrote - it was just nonsense.
 I have a 9-0V winding and two 30-0V windings.
  
 I got the instructions from Rondo Mueller how to connect everything.
  
 Still will need some more time before I can work on...
  
  
 To cheer up my mind I did something quicker and more easy:


----------



## stixx

DIY...?
  
 or Double Helix or the likes?


----------



## Sathimas

DIY of course 

Got the single wires from a mogami 2534


----------



## Mullet

I'm about to start doing preliminary case design. I know the dimensions of the complete boards are 150mm L x110mm W. What are the hole dimensions? My guess is 2.5mm in from the edges?


----------



## stixx

Mullet,
  
 the board size is correct, but 2.5mm from the edges wouldn't leave much for the hole itself.
 I measured on the print from the Cavalli website, and according to this the CENTER of the
 holes is 5mm from the edges with the hole being a bit over 3mm for an M3 bolt.
  
 Hope this helps!


----------



## Mullet

Cool that's good to know. 5mm from the edges will help with my layout in Visio.


----------



## Mullet

Question for the guys who added in the *E12* protection circuits...
  
 Looking at the directions on the E12 website, it looks like the EHHA would fit in the 2 channel *passive ground* camp, but with the special situation of having a split power supply requiring 2 E12s. Am I correct in this assumption? The only hang up I have is that I'm not 100% sure about the EHHA having *active or passive ground*. So if it's passive then I'd only wire up L+ on one and R+ on the other, right? ...and If it's an active then L+ L- and R+ R-. Would I just tap from the star ground for L- and R-? Hopefully, its clear what I'm asking.
  
 Also, my *bias* seems to move around rather than stay static. Once warmed up and set I seem to get about ±5mV fluctuations. Is this normal?


----------



## Mullet

Hey!
  
 Just a heads up. I don't want to make this a pity party. I recently killed a pair of DT880s while using this amp. I did all the checks - no dc offset, biased both boards, and temp wired everything up. I used KSC75s to test with. Since, I had lovely music (with a tad of really low level buzz in the left channel) I decided to try out my DT880s. I figured I could fix it with a ground loop breaker and/or better tighter wiring. The DT880s had the buzz, but way way less. Anyways, after a long listening session, I had turned off the amp with the pot all the way down. Then I fired it up the next day with phones plugged in and volume turned down. Once I raised the volume I could hear the right driver had way less audio than the left. I tested the phones with different amps, same result. I know another builder had similar issues and killed a few earbuds. He mentioned that he even had the volume down and could measure voltage spikes on power up and power down. I'm glad I'm going to be implementing E12s in this build to protect my other phones. I do realize that others haven't used E12s so it must be something else that caused it -- I'm using a crappy 1/8 jack for my signal output.  D'oh!


----------



## Klechty

Hi there,
  
 i recently added a dc protection to my ehha revision .
 I have almost finished it, i need to receive the power transistors.
 Here is the overall pcb.


----------



## Mullet

That is super cool. So I suspect this is based off the Rev A with BJT instead of mosfets. I suppose you only need one ±30v supply. Looks like you'll be able to minimize wires, etc. for star ground.


----------



## Mullet

If I'm able to get my chassis in order by the 10th, I'll be able to have things cased up by the NYC area meet on the 15th. I've never seen an EHHA at a NYC area meet, so I'm sure a lot of people will be interested in hearing it.


----------



## Klechty

mullet said:


> That is super cool. So I suspect this is based off the Rev A with BJT instead of mosfets. I suppose you only need one ±30v supply. Looks like you'll be able to minimize wires, etc. for star ground.


 
 Hi,
  
 this revision is totally based on the REv A , mosfet version ( that not appear in the pcb ) . The supply needed are the same than original 30v , plus the 12v for the lamps.I made a big work to minimize the pcb , it is now 170mm length. i will put some pictures when i'll finish it.
 Thanks for the interest.


----------



## Mullet

I'm pretty much at the finish line with my EHHA Rev A. and as usual I've hit another snag. I've had some crappy luck with DIY lately. Keeps life interesting and I'm not giving up.
  
 So here's the issue...
  
 I didn’t have time to take pics, but I’ll try and explain… When each board is separate (not connected together via SG) and powered up... on the “bad” board I get around up to 30mV offset. It jumps around and almost zeroes out. The “good” board zeroes itself out. When I connect everything via a terminal strip using ethernet type copper wire I get about 1.3VDC offset. Not good. The “good” board still zeroes itself out. I’m pretty sure I have to look at the servo to see what is going on. *What should I be looking out for?* Do I need to think about re-wiring my SG?
  
 I'm not sure if this is related to my earlier issue of killing headphones. I'm pretty sure I measured offset before plugging anything in. This was before I started casing things up. However, it's possible that it was related. At least at this point I have working E12s. I'm pretty bummed because I was hoping to have this ready for this weekend's NYC area meet and time is running out.


----------



## funch

I had a similar problem on one board of a semi-finished amp that I picked up on the FS forums. It turned out to be a cold solder joint on a resistor (R12 IIRC).  The original
 joint looked fine, but when I put pressure on the resistor from the top, the solder completely pushed away from the board. Sneaky little %*#@.


----------



## Mullet

Hrmmmm.. I've reflowed things. Didn't find any bad soldering. Maybe this requires a 2nd look. I did notice you've had this problem as well as others. Seems the EHHA's design is prone to this because of it being DC coupled. Hence the reason for the servo.
  
 I did find this...
  
 Quote:


gurubhai said:


> Here's how I would have go about troubleshooting.
> 
> 1) Look for any shorts
> 
> ...


 
  
 I know this is basic stuff and I should know most of this by now. But I just want to be sure I'm doing it right. I'd hate to create more damage than what is done.
  
 1. Checking for shorts. Best way to do this...
  
 2. Double checking components... I'm assuming this means one has put the parts in the their proper place.
  
 3. Check BJTs... I'll use the recommended site.
  
 4. What resistance should I expect for output mosfets? And at what points should I check?
  
 I think I'll have to uncase this puppy to get a better angle on what is happening. I suppose I can use the good board to help.


----------



## Mullet

Gosh this thread is dead.
  
 So I've finally gotten things sorted out and it's quite perplexing. I've re-flowed joints on the amp section of the bad board and used generous amounts of flux this time. I didn't change the wiring layout, so that didn't change. I did re-tighten the terminals due to removing the board for re-flowing. In any event, now things are working. I'm getting a maximum of 3mV offset on the bad board and around 1mV on the good board. There was a slight buzz, even with the pot totally turned down. I changed the power cable and have plugged it directly into my wall outlet and not the power strip I'm using. Now the buzz has gone away.
  
 How does this amp sound?
  
 Fantastic!
  
 It feels like all of my headphones are now totally driven with authority. There seems to be more width in sound stage compared to my other Cavalli DIY amp - the Compact Tube Hybrid. I guess you could say it's less congested. With more listening time and comparison to my other amps I'll be able to fully grasp what it does and doesn't do.
  
 On to my next project... the journey begins...


----------



## muskyhuntr

Congratulations on your build!!!  Looking forward to seeing some pictures.  Good luck on your next build!
  
 Me


----------



## Klechty

mullet said:


> Gosh this thread is dead.
> 
> So I've finally gotten things sorted out and it's quite perplexing. I've re-flowed joints on the amp section of the bad board and used generous amounts of flux this time. I didn't change the wiring layout, so that didn't change. I did re-tighten the terminals due to removing the board for re-flowing. In any event, now things are working. I'm getting a maximum of 3mV offset on the bad board and around 1mV on the good board. There was a slight buzz, even with the pot totally turned down. I changed the power cable and have plugged it directly into my wall outlet and not the power strip I'm using. Now the buzz has gone away.
> 
> ...


 
 sorry for the late answer.
 May be you get a faulty pcb.
 I'm working on a pcb without this annoying noise, i will post somme pictures when i receive it.


----------



## Mullet

Yeah, the noise thing is weird. It had gone away and now it's back with a vengeance. I don't think it's my input wiring (RCAs). I'm using belden cable for the wire, which includes three wires - black, red, and gnd. I usually cut either black or red and keep the gnd. Then I wire both the gnd and either black or red depending on left or right channel. Both go to my pot inputs. I'm using the AMB RK27 board with an RK27. I've tried isolating the RCA jacks using those fancy Rean RCAs. I'm pretty certain they are isolated from the chassis. Or at least I think so. Anyway to tell for sure?
  
 I'm thinking my star ground wiring is correct. I'm using the alternate wiring instead of the primary wiring on Alex's site. The only things that I can think of that relate to noise would be my transformers being too close. Can I just use copper foil to shield them?
  
 I'll probably take everything apart and start with different star ground wiring to see if that helps. I actually have a ground loop breaker in the mix, but it doesn't seem to have an effect to removing hum.
  
 I have some pix that I'll upload in a few hours.


----------



## Klechty

mullet said:


> Yeah, the noise thing is weird. It had gone away and now it's back with a vengeance. I don't think it's my input wiring (RCAs). I'm using belden cable for the wire, which includes three wires - black, red, and gnd. I usually cut either black or red and keep the gnd. Then I wire both the gnd and either black or red depending on left or right channel. Both go to my pot inputs. I'm using the AMB RK27 board with an RK27. I've tried isolating the RCA jacks using those fancy Rean RCAs. I'm pretty certain they are isolated from the chassis. Or at least I think so. Anyway to tell for sure?
> 
> I'm thinking my star ground wiring is correct. I'm using the alternate wiring instead of the primary wiring on Alex's site. The only things that I can think of that relate to noise would be my transformers being too close. Can I just use copper foil to shield them?
> 
> ...


 
 Yes you can cover the transformer with a copper foil. Don't forget to put the foil to the ground.
 The problem with the ehha is the number of cables that float around.
 This the reason why i did my own pcb.


----------



## stixx

I am selling my unfinished EHHA RevA --> boards all populated and fully working
 (had it playing on the breadboard for months).
 Standard psu exchanged with a pair of Salas shunt regs. For details look here:
  
http://www.head-fi.org/t/763448/fs-ehha-rev-a-boards-with-salas-shunt-regs-and-transformers


----------



## luxodesign

Hello all! I am here to ask for a bit of help. A good friend of mine has been looking at some of the DIY amp projects and asked for my help to assemble a kit. I agreed, I know my way around soldering boards and assembling arduino components and was happy to help. So he ended up purchasing the EHHA Rev A kit from GlassJar which I received last week and it looks great, very expertly assembled kit.
  
 The problem is I am in way over my head, I can read a basic schematic and I can do a clean solder job. I can NOT assemble this kit with a 100% certainty that I am not going to do something which will affect the quality of the sound. 
  
 If anyone out there could help me out with assembling this thing I can offer my services with CNC, laser cutting/engraving or even water-jet cutting. My company provides custom fab services and I was initially going to make him a case out of walnut to match his headphone stand specifically designed for whatever amp he chose.  In fact, I would be happy to trade some custom case work if anyone is interested. (I'm in California)
  
 I realize no one has been on this thread for months and the interest in the Rev A seems to have waned a bit, we are really keen to hear a true tube amp though so I'm hoping for the best!


----------



## stixx

You have the kit, you do know how to do a clean solder job, you probably have the tools... that's a good way to start.
  
 You don't necessarily have to be able to read the schematics when stuffing the boards... follow the BOM and the designations
 on the boards, CAREFULLY check which part goes where, carefully check orientation / polarity and, most of all, take your time!
  
 Start populating the heater and psu boards first since they are really easy and good practice to get aquainted with he EHHA.
 Then do the amplifier boards. As said take your time since desoldering parts on the amplifier boards will not be easy and unneccessary 
 when you do it right from the beginning.
  
 When you have achieved this come back here and ask for advice on how to wire everything up... there are diagrams etc., and
 probably good advice from one or the other visitor here... 
	

	
	
		
		

		
			




  
 When interested I can send you all the information I have on my computer about the EHHA RevA, PM me with an email adress!


----------



## Mullet

Also, I'd say to try and read the whole thread. There is a wealth of info that should help in getting it done. It's not a super hard project. The wiring is the most frustrating part I'd say. Looking back, I'd say I would have preferred a single board. A lot of people report having a low level hum, including myself. If there were less wiring then maybe it wouldn't exist. Perhaps, going with that custom transformer would help. All things aside, I have to say this is a great sounding amp though. Everyone that hears it at meets, has good things to say like... end game amp, etc.


----------



## luxodesign

Thanks for all the encouragement, I got the BOM from my buddy and can now see more clearly the correlation between it and the boards, this is going to be easier than I thought. That is to say, I thought is was almost impossible and now I think if I take my time I can get it done in a week or so 
  
 I have read through the thread and found some good stuff starting at page 30, but it still freaked me out pretty well.  I will try to post some pics as I go, I'll start on the heaters and work my way in.  
  
 Again, thanks for the responses, it's been a big help and we appreciate it.


----------



## luxodesign

Alright, I have some time this weekend and I'm hoping to knock out the boards. I am making some assumptions and I'd like some feedback if you all have time, I have not worked with some of these types of components before.
  
 So this the first heater board, I'm not going to do the second until I hear back (and I need some parts from mouser, dropped a resistor and subsequently crushed it with another project)
  
 I assumed the anode leg on the rectifiers was to be facing up, can you confirm? 
  
 On to the next boards, I am warming to the task and am now very excited to hear this amp. My buddy has some sort of crowdsourced headphones that I listened to and it was just fantastic even on his solid state. I got lazy years ago and traded the convenience of digital for a lot of sound quality, this project has really reminded me of I've been missing.
  
 Thanks again for all your help,
  
  
 OK, so I guess I can't upload a picture as I lack the necessary permissions.  I'll see if I can't get that fixed, would really like to post them as I go,


----------



## Klechty

Dude,
  
 i encourage you to read that.
  
 https://www.cavalliaudio.com/diy/ehhaa/main.php?page=boards


----------



## luxodesign

Yeah, that was the first place I went, I spent about a week researching this thread and other places online. As I said earlier I have only a very basic understanding of schematics and while the BOM may call out the right piece, I don't always know what that piece looks like. I am also very concerned about getting some of the polarities wrong and I've been using a multimeter to feel my way through the resistors so I don't mess that up.
  
 All in all I'm getting most of the board done, I'm going to do one channel first, trouble shoot it and then start the next set. I've ordered a spare board from GlassJar so that if I do screw anything up too badly it's an easy fix.  
  
 Really wish I could post pics of my progress, still working on that bit.
  
 Thanks again for all the support, I am hoping to finish at least the one channel this weekend,


----------



## luxodesign

OK, so I have one channel mostly done, I just need to confirm my resistors from GlassJar (they were larger than the PCB and I'd have to solder them in at a weird angle).  I am going to get some confirmation on all that and then I'll be ready to go.
  
 Many thanks again to Stixx for sending me some wiring diagrams, I'm going to have a go at it this week, maybe over Thanksgiving weekend if I have time.
  
 Apparently I have to post 40+ messages or so before I'm allowed to post any pics of my build. I am very tempted to to just post 36 additional posts but I have a feeling the Mods That Be will not look kindly on that (seriously, just joking, please don't boot me!)
  
 Anyone have trouble pushing in the tubes? I am a little nervous that I've done something wrong on the solder side (I even broke out the ol' 60/40 for the socket so I hope not) as when I went to fit the tubes to send a pic to my buddy they seemed extremely tight and I was worried I'd break something so I just stopped. I'll wait until I'm totally ready to go before I load up the tubes and chip.
  
 -luxo


----------



## Sathimas

It's alive !
  

  
 Some of you will remember my struggle with the ground wiring and non-defeatable hum.
  
 Now I finally had time to install the custum wound transformers I bought in *June 2014...*
  
  
 It's a real dual-mono build now since the transformers are 30-0-30 and 0-9V *each.*
 They also have two different shields, which are not connected atm.
  
  
*No hum anymore*, just some static hardly hearable with my Musical Fidelity MF200. 
  
  
 If this ain't no good start for 2016 :-D


----------



## stixx

Are those the transformers from Rondo Müller?
 If yes I am relieved since I suggested them when I recall correctly... I just had a big transformer made by Rondo for another project. 
	

	
	
		
		

		
			




  
 Happy New 2016!


----------



## Sathimas

You're right


----------



## dBel84

Congrats, that is a lovely looking amp ..dB


----------



## FallenAngel

sathimas said:


> It's alive !


 
  
 That's so sexy!


----------



## FallenAngel

Hey guys,
  
 What's the exact board size?


----------



## FallenAngel

Sathimas : What's that little board in the back?


----------



## Sathimas

Board size see cavalli Audio

The board in the back is an amb e12


----------



## FallenAngel

Thanks, but I haven't found the size on Alex's site.


----------



## Sathimas

Done ...

I'll look up the dimensions


----------



## Jrossel

sathimas said:


> Done ...
> 
> I'll look up the dimensions


 
  
 The Amp boards are 8.5 x 11, sort of like a sheet of paper but in this case it is cm.
 The Power supply boards are 4.5 x 11 cm, and the heaters are a thin  2 x 11 cm.


----------



## Chs177

Hello,
  
 could you please help or advise me?
 I'm building EHHA Rev A boards from GJA kit. I soldered one board and heater is ok, raiil is ok also. I have ~0.04V between out and ground.
 I have problem with bias setting, I'm reading 1,06V and -1.06V from TP1 and TP2 to out. I can only can adjust P1 trimpot to higher value not lower.
 Heatsinks on board become hot very quickly. I'm reading 29,7V and -29.4V from rail when I just switched power on and 28.7V and -28.4V after 10 seconds.
 Here is my board:

  
 I checked board and re-soldered it. Nothing is changed.
 What I am doing wrong? What I need to check?
 Thanks in advance!


----------



## FallenAngel

chs177 said:


> Hello,
> 
> could you please help or advise me?
> I'm building EHHA Rev A boards from GJA kit. I soldered one board and heater is ok, raiil is ok also. I have ~0.04V between out and ground.
> ...


 
  
 C7 cap looks blown on the top board.
  
 Something went very wrong there. Look at it closely for solder bridges.
  
 You should also be testing this with the tube installed.


----------



## Chs177

fallenangel said:


> C7 cap looks blown on the top board.
> 
> Something went very wrong there. Look at it closely for solder bridges.
> 
> You should also be testing this with the tube installed.


 

 Yes, the cap is blown but it's another story.
 I checked the board with tube installed for sure and I have bias 450mA.....


----------



## FallenAngel

Is C3 properly installed? It looks weird.
  
 Can you confirm R17 value.


----------



## stixx

> Thanks, but I haven't found the size on Alex's site.


 
  
 The board in question is from Amb Labs... the Epsilon 12 muting thing.


----------



## Chs177

fallenangel said:


> Is C3 properly installed? It looks weird.
> 
> Can you confirm R17 value.


 

 C3 is properly installed.
 R17 is 1,5K.


----------



## FallenAngel

chs177 said:


> C3 is properly installed.
> R17 is 1,5K.


 
  
 1) Look at every transistor and make sure they're in the correct position (2705/1145) and of course, confirm the 540/9540 are in their correct position.
 2) Flip the board over and take a clear photo.


----------



## Chs177

fallenangel said:


> 1) Look at every transistor and make sure they're in the correct position (2705/1145) and of course, confirm the 540/9540 are in their correct position.
> 2) Flip the board over and take a clear photo.


 

 Thank you! One board is up and running. I'm working on second board.


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## Chs177

Both boards are up and running. EHHA have an amazing sound. I'm find out a lot of useful information from this thread. Thanks all!


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## FallenAngel

Finished my build, fixed some grounding issue but still getting hum when the volume is above 50%. Any ideas on how to deal with it?


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## greyhorse

FallenAngel,
  
 Congrats on building up the EHHA.
 Overall your build looks ok, but please let me know the following:
  
 1. Input impedance of your pot.  I think I had a 100K Black Beauty in mine, but I seem to remember swapping it out with a 10K TDK conductive plastic unit after being plagued by hum.
 2. Is your star ground connected to the chassis properly?  It's hard to see from above.
  
 It's minor, but your safety earth connection to the star ground runs parallel with the 30VAC, so maybe if your star ground is floating it's picking up the AC.
 I prefer to drop the safety earth to chassis right at the 120V socket.  This also gives you the option of raising the star ground from earth by a few ohms (like with a NTC).
  
 Otherwise I'm not seeing too much wrong.
  
 -Jeff


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## bluemonkeyflyer

greyhorse said:


> FallenAngel,
> 
> Congrats on building up the EHHA.
> Overall your build looks ok, but please let me know the following:
> ...


 
  
 Guys,
  
 I've read the entire thread. I have my EHHA Rev A up and running on a rectangle of plywood.
  
 I FUBAR'd one channel by boogering the power supply trying to remove/replace a faulty LED. Ordered another 1/2 kit from Jeff and built it in lightning speed compared to the snail's pace the first go round. I had horrible snap, crackle, and pops from the new build. I finally narrowed it down to the V+ side of the amp MOSFET. Whenever I applied any kind of force on the amp heat sink, the noise got worse or went away depending on the side to side pressure. So, I reflowed the solder joints  of the MOSFET and the largest resistor on that side. That took care of the rice crispies.  
  
 I still have some hum at greater than 75% volume pot but that's negated by going to 50% volume pot and adjusting the source volume. I suspect the residual noise may attenuate once I have the amp installed in a proper metal enclosure. 
  
 Being a kindergarten electronics-soldering Newbie, I would not be this far along without this thread and mostly the ongoing advice and guidance by an amp building guru widely known on this, and other, forums....To You, Sir, hats off and much gratitude.
  
 The sound quality is wonderful!  Thank you, Dr. Alex, for making this project possible.  OK, onward to Bijou and CKK3 builds.
  
 ~BMF


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## FallenAngel

It's a 50k black beauty. When I disconnected earth ground, the noise is MUCH lower.
  
 The star ground is connected to the chassis via ground loop breaker (lowered noise).
  
 I'll try to move the star ground to the IEC.


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## FallenAngel

Moved the grounding to chassis-ground based with a ground loop breaker to IEC. Still seems that the only way I get very low noise is to remove the IEC from the equation, but that's obviously not idea.


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## Chs177

fallenangel said:


> Still seems that the only way I get very low noise is to remove the IEC from the equation, but that's obviously not idea.


 
 Why not? I saw many advices to don't connect power ground at all to avoid problem with hum and noise.
 Now I'm not connected power ground and have no noise at all on very sensitive headphones.
 You may also consider to use socket with EMI filter. May be it will help.


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## FallenAngel

Don't have one right now, but may need to check that.


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## funch

Here are some pix of my first Rev.A. Scroll to post #1282. As you can see, I took the term star ground literally. All of the ground wires, including from the IEC
 and headphone jack, connect to a brass 6/32 machine screw.  I never had a problem with hum.
  
 http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1275


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## FallenAngel

funch said:


> Here are some pix of my first Rev.A. Scroll to post #1282. As you can see, I took the term star ground literally. All of the ground wires, including from the IEC
> and headphone jack, connect to a brass 6/32 machine screw.  I never had a problem with hum.
> 
> http://www.head-fi.org/t/506984/ehha-rev-a-interest-thread/1275


 
  
 Very nice build.
  
 I don't think I connected my 6.3V supply to ground, so I'll do that next.


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## stixx

> Why not? I saw many advices to don't connect power ground at all to avoid problem with hum and noise.
> Now I'm not connected power ground and have no noise at all on very sensitive headphones.


 
 Not a good idea. You can omit connecting power ground in digital gear or other low power devices, but you should never do that in anything that contains the word "amplifier". 
 When you only can get your gear humfree with leaving ground unconnected your wiring or else is bad.
 There's also information posted on the Cavalli site about alternate wiring to try in case of hum.
  
 Member Sathimas posted a while a go that he needed new (better) transformers to get rid of hum (probably because of the proximity of the trannies to the amplifier boards). When you have a good central ground point where all the individual ground wires are connected you should not have hum. Of course also tie the heater supply to that point! (--> Fallen Angel). Also try to have the rectifiers facing away from the amplifier boards.
  
 I am at No 12 in my row of headphone amplifiers, and none of them had/has hum issues... I didn't even need Ground Loop Breaker.


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## bluemonkeyflyer

fallenangel said:


> Finished my build, fixed some grounding issue but still getting hum when the volume is above 50%. Any ideas on how to deal with it?


 
  
 Looks real good, FA.
  
 Here's what I did based on guidance from experienced builders:
  
 For the hum, you could try shielded cables from RCAs to the pot and tie the shield to the RCA ground terminals, not at the pot.
  
 Maybe moving the pot to the TRS jack position and moving the TRS jack to the pot position would help by shortening the distance from RCAs to the pot.
  
 I had spaghetti wires all over the place so I cleaned up the mess with the shortest wiring configuration possible with tightly twisted all hookup wires, laid them out at 90 degrees where they crossed, moved the transformers and boards as far away from each other as possible, and made my star grounds like Stixx described.
  
 I still have it mounted on 14" x 19" plywood and it's dead quiet until the volume pot is turned up to 80%. From what I've read, here, installing inside a metal enclosure may further improve the "blackness."
  
 The bit in the middle is a ground loop breaker.
  
 The sound quality is great! I'm looking forward to 3 more amp builds....
  
 ....Now, be gentle. This is my first build so don't laugh too much:


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## stixx

No reason for laughing... you did everything right!
 Now just put it in  case big enough.


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## FallenAngel

Thanks for the help guys!
  
 It seems simply connecting the 6.3V supply eliminates the noise completely.
  
 I did manage to make the ground slightly cleaner, but really not by much.
  
 It works great now but there's one major thing that I'm sure you could all comment on: What's with the nasty turn-on noise? It feels like the first 5 seconds are buzz and a nasty click before it goes dead quiet. What could I do about this? How have you dealt with this?
  
 Thanks again.


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## bluemonkeyflyer

fallenangel said:


> Thanks for the help guys!
> 
> It seems simply connecting the 6.3V supply eliminates the noise completely.
> 
> ...


 
  
 Get amb.org epsilon 12.
  
 Otherwise, don't turn on the amp with headphones plugged in and don't turn off with headphones plugged in or you risk zapping 30k mV into your headphones. I fried a set of Koss PortaPro when I forgot to unplug them before powering on.
  
 The epsilon 12 will protect your headphones in the event of a surge or power failure.
  
 I'm interested how you laid out your star ground.


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## FallenAngel

Having already burned two pairs of headphones in this amp, I think a muting circuit is a must.


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## FallenAngel

I actually have an old e12 v1.1 board, so I'll probably stick that in.


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## Chs177

fallenangel said:


> I actually have an old e12 v1.1 board, so I'll probably stick that in.


 

 There are kits on ebay and ali based on upc1237.
 http://rockgrotto.proboards.com/thread/8187/headphone-protector


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## FallenAngel

chs177 said:


> There are kits on ebay and ali based on upc1237.
> http://rockgrotto.proboards.com/thread/8187/headphone-protector


 sold out


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## Chs177

fallenangel said:


> sold out


 
 http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.Xupc1237+headphone.TRS0&_nkw=upc1237+headphone&_sacat=0
 Or just search ebay with keywords: upc1237 headphone. You will find several kits.


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## Klechty

Here's another revisited EHHA .
 6h28b mini tube to reduce the high.
 Replace the japs trans by BC639/BC640.
 Replace the current constant tube diode (j511) by a more accurent one (lm334z).
 Added a dc protection based on the E12.
 Change the output current.
 And more ....


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## FallenAngel

klechty said:


> Here's another revisited EHHA .
> 6h28b mini tube to reduce the high.
> Replace the japs trans by BC639/BC640.
> Replace the current constant tube diode (j511) by a more accurent one (lm334z).
> ...


 
  
 VERY cool!


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## Klechty

thanks.
 i'm working on another one with some others improvements.


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## Sathimas

Back with new problems ...
  
 My post some months ago was (maybe) too enthusiastic.
  
 Since the Ehha is said to be producing voltage spikes capable of frying headphones
 I installed an AMB e12 which is now troubling me.
  
 I can turn on the amp, go through the adjustment of the e12 and listen to some
 music then for several minutes, then the e12 engages and stays "shut".
  
 Offset on the EHHA channels (G and OUT) is drifting a bit but never higher
 than 4 to 5mV, mostly it stays at 0.
  
 Starground to IEC is connected via the groundloopbreaker I installed last year.
 I have no audible hum as long as the e12 lets the signal pass.
  
 I can not re-adjust the e12 on the "warm" amp since the voltage between VG
 and G of the amp is about 160mV then and drifts around a lot. Impossible
 to get it back to zero.
  
 Here's the wiring used at the moment:

  
  
 Any idea?


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## bluemonkeyflyer

sathimas said:


> Back with new problems ...
> 
> My post some months ago was (maybe) too enthusiastic.
> 
> ...


 
  
 I have Epsilon 12 powered off the +30 and -30 rails. It doesn't engage until the amps heat up and stabilize.
 I'm using the standard wiring diagram, not the alternate one....it made no difference in hum at higher volume pot settings. A ground loop breaker helped a bit.
  
 What is the purpose of the star ground connection from the amp output terminal?
 Do you have the star ground from the amp input terminals connected to the star ground?
  
 BTW, I had a problem with two Epsilon 12's (each tried separately, not together) in my EHHA Rev A. There were two problems:
 1. 2N7000 was not soldered on top of the board...the solder did not flow up from the other side so I added some solder on the top joints.
 2. This did not solve the problem. I re-biased EHHA Rev A and both Epsilon 12's work.


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## Sathimas

Updated the picture of the wiring, didn't seem to work properly.
  
 Quote:


> It doesn't engage until the amps heat up and stabilize.


 
  
 By "engage" *I *mean it switches *off *the outputs.
  


> What is the purpose of the star ground connection from the amp output terminal?


 
  
 I don't quite understand your question?
  
 Amp out is *not *connected to star ground.
  
 Amp ground (next to Amp _out_) is directly connected to the jack from both boards.
  
  
 Star ground is connected to the ground tap of the power inlet (called "IEC" in my last post).
  
  


> Do you have the star ground from the amp input terminals connected to the star ground?


 
  
 yes, see the picture for the wiring, it works now.
  
  
  
  
 Hope I could clarify things a bit.


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## bluemonkeyflyer

sathimas said:


> By "engage" *I *mean it switches *off *the outputs.
> 
> 
> I don't quite understand your question?
> ...


 
 Sorry, I didn't mean the Amp Out terminal. I meant the ground terminal from the Amp Out Terminal Block.  Yes, I see the picture. What is the purpose of this extra ground connection?
  
 I have the Amp Out ground terminals from both amps to Star Ground.


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## Sathimas

> What is the purpose of this extra ground connection?
> 
> I have the Amp Out ground terminals from both amps to Star Ground.


 
  
 There is no *extra* ground connection, since the jack is not tied to Star ground,
 but to the amp out ground terminals directly.
  
 Tried this while solving my hum problems.
  
 I could try the old sheme now ...


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## bluemonkeyflyer

sathimas said:


>


 
 OK. It may not matter, but weird ground eddies may be at play. Cavalli's Alternate Wiring Diagram shows the amp Out ground terminals are not connected. Instead, the amp In star ground terminals are connected to the star ground. It's worth a shot in the dark.
  
 BTW, I edited my earlier post to clarify a few comments.
  
 Good luck!


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## bluemonkeyflyer

sathimas said:


> There is no *extra* ground connection, since the jack is not tied to Star ground,
> but to the amp out ground terminals directly.
> 
> Tried this while solving my hum problems.
> ...


 
 OK. By "extra ground connection," I meant extra as one not shown on Cavalli's wiring diagram. No offense intended.
  
 Maybe I should try your scheme to see if it helps my hum issue.


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## Sathimas

no offense taken.
  
 Ground wiring on the EHHA is really confusing ...


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## Sathimas

Well, this amp is driving me absolutely mad.
  
 I changed the resistor-values according to ambs website to decrease the sensivity of the e12.
  
 While doing that, I changed nothing about the internal wiring of the amp.
 (It was hum-free before)
  
 Now after getting the e12 (half) to work (still a bit jumpy) the hum is back.
  
 Changed the ground wiring to cavallis alternative wiring then with no
 effect - changed to normal ground scheme and the hum was gone.
  
 For some reason, the e12 cut off the outputs then and when sound came back,
 the hum was there too again - without changing anything in the wiring.
  
  
 I just don't get it, this is ridiculous...


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## Sathimas

Adding my newest observation:
  
 Had the phones connected directly at turning on the amp,
 had no hum when the e12 let the signal pass.
  
 Got hum, starting quiet and becoming louder after a few seconds,
 the hum started to "oscillate" getting loud and quiet at maybe 1 
 volumen-change per second - then the e12 started to switch on and off.
  
  
 Any idea where the problem might be?


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## Klechty

As I see many people complaining about the hum, I will give you one tip. 
Thus him is usually done by a bad tube implementation, so is the ehha. 
Cut the capacitor ground, pin 9 of the tube. And directly connect it to the general ground.


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## Sathimas

Hi there - I need the EHHA Rev A schematic for the troubleshooting of my and and can not find it anywhere - can someone give me a link (via p.m. if nessesary)


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## bluemonkeyflyer

Sathimas said:


> Hi there - I need the EHHA Rev A schematic for the troubleshooting of my and and can not find it anywhere - can someone give me a link (via p.m. if nessesary)



PM your email and I'll send you the schematics.


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## Sathimas

Hi there,

I'm back trying to bring my EHHA to life - hope there's still some people active here.

I'm still at the point I was about 18months ago (just had him sitting under the table...):

I'm not able to set up the AMB e12 properly.
When I try to get the voltage between the amps grund and VG to zero
this just won't work - the voltage drifts from about 200mV to -200mV.

I discussed that the AMB himself in over at the AMB-website and he says the
e12 is working properly (https://www.amb.org/forum/adjustment-problems-strange-behavior-t3250.html)

Does anybody have a hint for me where to start looking for the mistake?


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## Mullet

@Sathimas  I've had strangeness with my E12s constantly drifting before. I deduced it to the connections on my phoenix type connectors. They were a little janky and needed to be readjusted. Not sure how you have yours setup. Did you ever solve your hum issues?

With regard to hum... oh boy! I've had very similar issues. Hum would be low in volume at some points, then at others be quite loud. The loudness also changed with the type of headphones.  Thus far I've removed my E12s to see if that would do the trick. I also changed up how I'm doing the star ground. I basically tied the ground from the power supply to the amp board. Then don't run the ground from the heater supply board, but double up on ground from the gnd heater position at the amp board to star. This eliminates a few wires, but hum didn't subside. My next move is to use shielded cabling everywhere, but I'm skeptical that that'd work. Other than that the last ditch effort would be to change out the transformers. I'm using the Avel Lindberg trafos. I'm thinking they might be the cause. I'd be curious to see whether people using the SUMR transformer have experienced the same issue...

Any ideas would be helpful... I can take some pics to illustrate my setup if need be.


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## muskyhuntr

I used a SUMR transformer in my build.  Spec'd shielded, potted and encapsulated.  My build was quite.
I did not follow recommended grounding configurations.  Check some of my prior posts to see what I did.
Sold the amp a few years back to fund other projects, so I cant pop the lid.

Me


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## Sathimas

The hum issue was not solved yet - I just can't find the time (and motiviation...)
to take the EHHA back to the workbench and tear things apart again.

I use custom wound transformes with shield, yet the shield is not used atm.

I'm grateful for any hint or whatever help you can give.


Maybe it's time to attack again


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## stixx (Mar 23, 2018)

I remember very well your continuous fight to tackle the hum issues..

Same as muskyhuntr I sold my EHHA a few years back while it was still on the breadboard...
it was absolutely quiet then with a "standard" star ground.
--> everything goes to* one* point connected to chassis, but there can be *sub-stars* that
then connect to the last one that goes to the chassis. It is best to have your star ground
near the big capacitors of the psu. The ground of the E12s ties into the star theme as well.

I have had minor hum or buzz issues with my solid state amps but was able to get rid of them.
The reason was either an unshielded toroid (changed to a shieded one [Dynahi]) or improper
wire routing. With the amp on just moving wires around can give an indication... I used a small
sheet of copper on one of my other amps where signal was too close to mains wiring.

Still it sounds that you might have different issues... Since the E12s is causing you trouble I
would ditch it... better unconnect your 'phones each time before you switch on or off. Don't
remember whether the EHHA has start up spikes in voltage, but better be safe than sorry.

Then I would roll tubes (I still have some if you need them  ) and do the wiggeling or
better moving. Just pressing wires down to the aluminum bottom made a difference in my
(successful) attempts. Hope it is not the proximity of things in your (beautiful) case.


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## Sathimas

I don't use the EHHA atm since it's not really working.
The switch-on and off spikes are present and quite high - that's why I'd like to keep the e12.

We had it running on the workbench monitoring DC offset for more than an hour
and it showed rare spikes near 40mV, yet the e12 did not engage then. There
was no source connected. Both channels had the same behavior.

For now I'd have to tear everything apart and re-wire it wire by wire,
starting with one board and then adding the other. 

Main problem - I can't bring up the motivation.
Remember - I bought the boards August 2011, almost 7 f**cking years ago.


Right now we're planning our new house which will built next year, our third
child is on the way (end of August) and there's work to be done too...

I'm not complaining, there's still time for DIY - just did my first real speaker-
development and more's to come. I just prefer to do thing's which seem easier than the EHHA.


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## stixx

I know what you mean... I would have long set it aside for good.


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## Mullet

Klechty said:


> As I see many people complaining about the hum, I will give you one tip.
> Thus him is usually done by a bad tube implementation, so is the ehha.
> Cut the capacitor ground, pin 9 of the tube. And directly connect it to the general ground.



This is a good point. I'd only try this as a last resort, even after replacing the Avel transformers. Just curious... what is wrong with the tube implementation?



stixx said:


> I remember very well your continuous fight to tackle the hum issues..
> 
> --> everything goes to* one* point connected to chassis, but there can be *sub-stars* that
> then connect to the last one that goes to the chassis. It is best to have your star ground
> near the big capacitors of the psu. The ground of the E12s ties into the star theme as well.



I know this is meant for @Sathimas, but it applies to anyone else who has built this amp as well. The one thing I'm curious about is star ground connecting to the E12s as well. I didn't do this. I was under the impression that the E12 has it's own virtual ground and that we're supposed to supply only ±30V from each PSU. Also, to get the correct pot settings on the E12 you'd measure from SG to that VG point on each E12. Correct me if I'm wrong, did I wire up the E12s incorrectly? BTW I still get hum with or without the E12s so my issue is something else.



stixx said:


> I have had minor hum or buzz issues with my solid state amps but was able to get rid of them.
> The reason was either an unshielded toroid (changed to a shieded one [Dynahi]) or improper
> wire routing. With the amp on just moving wires around can give an indication... I used a small
> sheet of copper on one of my other amps where signal was too close to mains wiring.



Moving around wires hasn't proven to illustrate where my issues are coming from. Maybe I need to come up with a better method of doing this. I'm hoping the shielded wiring everywhere is the fix. I'd hate to think it's an issue with the boards themselves. At that point, I'd probably just scrap the amp completely.



stixx said:


> Then I would roll tubes (I still have some if you need them  )



Ha! Yeah I've definitely got more tubes than I know what to do with... if you have Teles I might be interested tho


----------



## stixx

Mullet said:


> Just curious... what is wrong with the tube implementation?



Kletchy says that the tube is badly implemented in terms of grounding and suggests to connect pin 9 directly to ground instead 
to the pcb ground... when I read him correctly. Could in fact be that the boards have an inherent mistake in them which would 
be the reason for many having trouble with hum...



Mullet said:


> Correct me if I'm wrong, did I wire up the E12s incorrectly?



Cannot tell, have never dealt with the e12... and the Amb site doesn't load for me at the moment?? Usually ALL components
of an amplifier are tied to the same ground, but as I said, cannot tell in case of the e12.



Mullet said:


> I'm hoping the shielded wiring everywhere is the fix.



I hate to say it... but when you have hum issues shielded cable might not help... more when it's buzzing. Usually twisted pairs
should do the trick.



Mullet said:


> if you have Teles I might be interested tho



No, no Teles.


----------



## jfiveeight

Hello thread, i ended up with @muskyhuntr 's ehha revA.  I read back a page or two and he had mentioned he grounded it differently.  Anything I can help with here?

I am also seeing issues with the amb e12 but only on the right channel, sometimes it works.  I have yet to troubleshoot it.


----------



## muskyhuntr

I doubt that the e12 is giving you problems, more likely the right channel needs re-adjustment.  I no longer have the specs  on the amp, but adjusting to specification should solve your problem.
If the e12 is still acting up, then re-adjust it according to AMB's web site.  Wouldn't hurt to check the left while you are at it.

Me


----------



## jfiveeight

I will check it.  The build fit and finish, sound, and documentation are amazing.  Did you find the 6GM8 tubes to be the best sounding?


----------



## muskyhuntr

I did not roll any tubes in this amp.  Liked it the way it was!

Me


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## Stillhart

What are the chances that the specs and build info for this (and Alex's other DIY projects) will ever be posted again?


----------



## stixx

Alex Cavalli basically stopped supporting the DIY crowd (understandably) when he went commercial.
I don't expect to see his pages back online unless he goes back to DIY... hard to foresee.

When you are interested in information about the EHHA's though I advise to visit the Way Back Machine
(internet archive) and browse for the Cavalli site. Most of the pages can still be found there... you 
have to browse late 2016/early 2017.


----------



## funch

Here is the home page for the EHHA Rev. A from the Wayback.

https://web.archive.org/web/20160622071235/http://www.cavalliaudio.com:80/pages/ehha-rev-a


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## Killercrush

proid said:


> I was wondering if i could use 12au7?  The plate voltage is limited to 30V only but there are good souding amp like project sunrise only run at 13.5V plate



Just got a REV A here and was wondering the same thing, is it doable with some mods ?!


----------

