# [SripBoard Design] Starving Student Millett Hybrid Vacum Tube Amp



## TestSubject

*EDIT: This is old. Please, go have a look at the lastest post as the Stripboard design as greatly improved and i hope will be operational soon. Here is Rev 3.7: LINK*
   
*Components are ordered, Will start building soon.*
   
*Looking into a 1 Tube re-design to the SSMH: LINK*
   
*Build Started: LINK*
   
*Build Finished / Pictures: LINK*
   
update: Still running strong! I use it everyday. Changed the led color for something... warmer...
   
   

   
   

   
  Ok so here is the Final Design, It works great and is simple to build. I have come a long way since I started this thread.
   
  I used DIYLC for this project and here is the board design, feel free to modifie it and share it around. It would be nice, if you choose to use this, to post results in this thread.
   
   
  Great Source of Info and BOM here: DIYForum
   
update: Realise I never had uploaded the design file.
   
     
   
  Here is an updated diagram with fixes and clarification from KimLaroux.
   

   
  Note that the red marks are cut strip

   

   
   

   
  Note: Use bigger heatsink than me!
   
  Special Thanks to:
Digger945 For 1) Sending me the parts 2) Taking Lots of his time explaining electronic concepts 3) Being such a nice person?
nikongod For helping Troubleshooting the Amplifier
Fred_fred2004 For inspiring me and general help.
zammykoo Frodo Brother in SSMH
KimLaroux for the updated diagram.
   
  And thanks to all the others for your support.
   


Spoiler: Old%20Original%20Post



 
  Good day,
   
  Well here i finished my Cmoy amp and since helped 3 friends make one as well because they fell in love with mine... I am probably not the first person in this situation.
   
  I really want to make a desktop amp and i thought that a Vacum tube amp would be great (awesome vintage look in bonus) so naturally i looked at the Millet Starving Student Hybrid amp for it's simplicity as i am still a beginner.
   
  The problem is that im not a fan of messy wiring, i was wondering if someone had made a stripboard layout for such an amp?
   
  Also the concern of the unavailability of the 19J6 tubes.
   
  The closer i found was this: Spanish Link
   
   
   
   
   
   
   
   
   
   

   
  also:
   
   
   
   
   
   
   
   
   
   
   
   


> Original Thread 00940: Then a simple amp like the kaidan could possibly do the trick:http://www.wavebourn.com/forum/viewtopic.php?t=998


 
   
  it does look simple but not much info is available on "the kaidan"

   
  Any info on this simpler amp? Note the use of higher voltage.


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## jdkJake

http://www.diyforums.org/SSMH/SSMHoverview.php


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## TestSubject

Thanks but... nothing more here that i didnt know before or is there something in particular that you might want to point out over on the site?
   
  Thanks anyways.


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## jdkJake

I thought by 'stripboard layout' you were looking for a PCB layout. As such:

http://www.diyforums.org/SSMH/SSMHlayout.php

If I am mistaken, then my apologies and disregard my postings.


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## deadlylover

Try and figure out a layout for yourself using the schematic, it's not very difficult for a simple amp like that. Keep in mind you may still need a little bit of extra wiring, but you can hide it away on the underside of the board.
   
  Once you got that down, you can build all sorts of wonderful things, as the skills you learn will come in handy.


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## kchapdaily

im building one right now on radioshack prototype board because i find it easier than p2p, its not too hard to come up with a layout


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## TestSubject

Quote: 





jdkjake said:


> I thought by 'stripboard layout' you were looking for a PCB layout. As such:
> 
> http://www.diyforums.org/SSMH/SSMHlayout.php
> 
> If I am mistaken, then my apologies and disregard my postings.


 

 This i what i meant for a stripboard:

   
  But thanks anyways.
   
  Yes i am working on some layout for a stripboard but a layout made but a someone with experience would certainly work better then what ever i can come up with. Dont forget I am a beginner, i want to learn and yes it would maybe be better for me to do everything on my own but have no idea how to deal with so many earthed leads without tons of jumpers for exemple. I dont want to go to the store and buy an amp, idont want to order a kit either but am i ready to design my own strip board? i dont think so.
   
  If no one i ready to help me, i understand, might be for my own good.


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## kchapdaily

in that picture it seems like you have rails, each row is connected. make one rail positive and one ground. that way you can put components you know are grounded right on that rail.
   
  without a custom made board your going to have a fair amount of jumpers.
   
  just go for it! if it doesnt work, check your work, and if you dont see anything sticking out at you, desolder everything and try wiring it up again, but differently. sometimes the best way to learn is to jump right in and give it a go. it doesnt have to be pretty, and one layout isnt necessarily better than another.


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## nikongod

The fact that some people cant point to point cleanly (points at self) doesn't mean *you* cant. Even if your work looks like garbage, like mine, there is mega-whoa-alot of pride to take in building something yourself from a schematic.
   
  You might save 3 wires by building the amp with the aid of stripboard. When you start counting connections on the stripboard, you certainly have more wire - particularly if you lay the amp out so that most connections can be made with the components themselves. 
   
  For example, here is my take on the starving student, using the tubes from the original millet hybrid:
   



   
  Its got 3 knobs because thats 3 times as good as 1. Seriously, its an older version of the akido stepper. 
   
  Innerbits:



   
   
   
   
   I may have managed to get MORE wire into this amp then most people get into the starving student. I got skills. 
   
  Maybe its just me, but I find building stuff on perf-board more time consuming and tedious than really old school point to point with nothing but tube sockets and tag strips. 
   
  The Kaidan is more complex than the Starving Student by a few components, and separate AC and DC feedback loops.


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## kchapdaily

as a side note, where/what kind of heat sinks are you using for the mosfets?


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## Sganzerla

This is funny, the original picture is from my Photography blog, which is in written in Portuguese (Brazil). 
   
   I can't help you but if you could read the text, I'm pretty sure you would think twice about building a headphone amp that uses 19J6 tubes, as it is/was hard to find those tubes. For the price I see people listing those amps here, unless it is for the experience of building something, there is no point getting in this trouble.


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## nikongod

Me?
  I used a little screw-on heat-sink on the back panel. You can kind of see it screwed to the back panel right in the middle. 
   
  My design runs the mosfets at significantly lower power dissipation than the original starving student so I can get away with a smalllllll sink. For real Starving Stdents the theme seems to be "more heatsink, more better". If I were building another one of these, I would use a larger heatsink (or 2 of these - I used only 1) but this one was adequate for me.


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## kchapdaily

aaahh i see it now


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## TestSubject

This is very hard, maybe a perf board design would be better.


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## TestSubject

I am having trouble with the design... Maybe a perfboard would make things simpler. I Can see the ton of jumpers needed already.
   
  Any explanation on the new kinds of tubes needed and the modifications needed to the design now that the 19J6 is gone?
   

   Quote:


>


 
   The Kaidan is more complex than the Starving Student by a few components, and separate AC and DC feedback loops.
   
  Is there any pics out there for reference? Maybe you built one yourself?
   
[size=medium]  [/size]​


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## nikongod

I found this on a quick google images search for "12au7 starving student schematic" 
   





   
  It can also be found HERE In the great Starving Student thread.
   

 RE my statement about the kaidan amp. 
  Quote: 





> Originally Posted by *TestSubject* /img/forum/go_quote.gif
> 
> Is there any pics out there for reference? Maybe you built one yourself?


 
   
  There is a schematic in the first post. I read it, and theres more stuff going on in the "audio" section. You will also need to build a high voltage power supply VS just buying a power brick for the Starving Student which adds still more stuff. 
   
  On that note, no, I have not built the kaidan amp myself. It seems like it could be nice, but is without a doubt a more involved build than a Starving Student.


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## kchapdaily

why must you build a power supply when its ok to just get a wallwart for the original?


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## nikongod

I was referring to the kiadan amp. The 12au7 starving student runs on the same wall wart as the 19j6 version. 
   
  On the note of the Kaidan amp I suppose you could buy a prebuilt 170V supply, a (whatever voltage) supply for the heaters, and then wire them together.
   
  But at that point your at least $50 into the PS which takes you pretty far for DIY stuff. And people like the look of high voltage power transformers AND this gets you your choice of parts which IMO makes slight additional expense totally worth it.


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## kchapdaily

i was actually trying to find some info on diy power supplies but i didnt come up with much.
   
  the ones from amb are nice but they only output up to 36v.
  could you point me in the direction of an affordable-ish diy power supply i could use for the starving student and other higher voltage tube amps?


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## nikongod

For the starving student its hard to get less expensive than the 48V brick supply everyone uses. MPJA.com sells a few power supplies that MAY be slightly better than the brick (linear regulated, ooh, aah) but for at least twice the price I dunno if Id do it. 
   
  Once you get past ~50V just build the power supply for the amp. Many tube amp schematics are paired with suggested power supply designs.


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## kchapdaily

the only reason i ask is because i ordered the cisco wall wart for the starving student june 29th and its not scheduled to arrive until august 2nd  kind of a bummer because thats the last thing i need. i could finish building it tomorrow but theres no way to test it out until the power supply arrives. would it be possible to hook up 5 9 volts and 2 AA batteries to get all 48 volts?


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## nikongod

I dont think a stack of 9V batteries will supply adequate current (~300mA). Just wait it out.


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## kchapdaily

good call. i added up the voltage but forgot about the current.


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## TestSubject

Well here is half of it... How does it look? This is my first time attempting anything like that.
  Green line are grounds. Thanks for having a look.


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## TestSubject

Quote: 





nikongod said:


> I found this on a quick google images search for "12au7 starving student schematic"


 
   
  Any difference in the parts list?


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## digger945

One link for the 12au7 amp...
http://diyaudioprojects.com/Solid/12AU7-IRF510-LM317-Headamp/
   
   
  ....I think there is more than one version of this amp.


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## TestSubject

Thanks for sharing ! Looks great
   
  Wonder how it compares to the SSMH, and its to bad it's a mono amp any alternatives?

 also found this, it's small enough to fit into an altoids! i thought i would share: Link
   
  REDIT: Not a mono amp sorry. This mislead me:


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## pabbi1

Bah, build it balanced...


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## digger945

Quote: 





testsubject said:


> Thanks for sharing ! Looks great
> 
> Wonder how it compares to the SSMH, and its to bad it's a mono amp any alternatives?


 
   
   
   
   
   
   
   
   
   

 also found this, it's small enough to fit into an altoids! i thought i would share: Link
   
  REDIT: Not a mono amp sorry. This mislead me:
   

   
  I think that you may have a small misunderstanding about what you are seeing in the schematic. The amp that I posted a link to, as well as the amp you posted above, are schematics for a single channel(one channel). You must multiply this schematic by 2 for a stereo amp. The 12AU7, like many tubes(but not all), is a dual triode tube, having inside it's glass shell 2 independent triodes(devices), so that each triode can be used for just 1 channel(left or right), and so you only need 1 tube for a stereo amp, using this particular type of amp topology. Comprendre?


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## TestSubject

So:
   
  1) The 12AU7 tubes can handle 2 channel per tube
  2) The amp from the link you gave me only uses one of those channel so two tubes (plus the reciprocal of the circuit) would be needed in order to output stereo
  3) The SSHM must be the same because it uses 2 tubes.
   
  Thanks for the help you are supplying.


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## Maverickmonk

are 4 tubes necessary? couldn't a dual mono 2-tube be made by splitting the ground planes? or isn't dual-mono the same as balanced?


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## digger945

Quote: 





testsubject said:


> So:
> 
> 1) The 12AU7 tubes can handle 2 channel per tube
> 2) The amp from the link you gave me only uses one of those channel so two tubes (plus the reciprocal of the circuit) would be needed in order to output stereo
> ...


 


  1) Yes.
  2) & 3) The SSHM uses 1 tube per channel, and that 1 tube per channel has both triodes (within the 1 tube) both paralleled. The other designs given here only use 1 tube, and just use 1 of the 2 triodes per channel.
   
http://www.nj7p.org/Tube4.php?tube=19J6 Data sheet for 19J6
   
 http://tdsl.duncanamps.com/show.php?des=12AU7 Data sheet for 12AU7
   
  Part of the reason for the dual triode per channel in the SSMH is because of the unique heater voltage/current, and the fact that it is used in series with the output mosfet, along with the 48V power supply. It is trying to get the most amp, using the very least amount of parts possible... almost.


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## TestSubject

Thanks i understand now!
   
  Any Difference in quality with the SSHM?
   
  Is there a Stripboard/Perfboard Layout available anywhere? I know you are getting tired of me asking for layouts all the time but last time i tried to make a layout (1/2 a layout actually) on my own, it was so bad no one even commented on it.
   
  Thanks for all this help your providing me.


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## Ikarios

If no one has suggested this before, sit yourself down and take a good long look at the schematic. Got it? Okay, now draw out that schematic using real life parts. That means drawing capacitors, resistors, the mosfets, the tube sockets, the potentiometer, input/output jacks, the whole shebang. I suggest getting several pieces of paper and a pencil and just doing this for like an hour or so. Eventually you'll get good enough at reading the schematic that you know where everything is and how you should go about laying out the components in whatever enclosure you decide to put it in. This is how I put together my 12AU7 SSMH. When you've come up with a layout that looks ideal, post it here and we can tell you if there are any problems with it.
   
  It took me about a month of planning to put together this SSMH as my first full project, but if you're willing to put in the time it's very rewarding. If you're not willing to put in the time, then why are you considering DIY?


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## TestSubject

You are a bit hard on me but i understand your point.
   
  I drew the schematic and it is true that i get a better idea of how things will be put together. Now i am not sure it will be easy and set everything up on a perfboard without over 9000 jumper is going to be a headache.
   
  What are your take in the difference between SSHM and the Single Tube alternative stated above?
   
  Off to bed now...
   
  First (6 am)attempt:


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## digger945

^That is what I do. After drawing the layout maybe 20 times, then I will try to make the actual parts fit into my selected enclosure. 
   
  Have you tried to see if you can get the tubes, or the 48V power supply?


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## Ikarios

Be careful about the mosfets - the schematic refers to it in numbers 1, 2, and 3, where 1 is gate, 2 is drain, and 3 is source. These numbers correspond to the pins like so: http://wb5rvz.com/sdr/components/irf510.gif
  So pin 2 of the mosfets (drain) should connect to each other and the resistor should be connected to pin 1. Several people have burned out mosfets by connecting them incorrectly, so it'll save you a couple bucks to make sure you have them properly hooked up.
   
  Furthermore it looks like you drew the schematic for the 19J6 original. I don't know about you, but I had a hell of a time trying to find 19J6 tubes last summer, so I gave up and went for the 12AU7 variant instead. That schematic can be found here: http://diyforums.org/SSMH/variants/SSMH-12AU7.gif
  There are not many changes, just a couple resistor swaps and a reassigment of the pin socket numbers.
   
  Otherwise the drawing looks good. I'm not too familiar with the 19J6 schematic so I'm not looking carefully for errors. If you want some guidelines on how to build a P2P 12AU7 you can look through the main SSMH thread for Beftus' build pics (search for his name and find some of his earlier posts), and mine as well. My album can be found here: https://picasaweb.google.com/submergence/StarvingStudentMillettHybridSSMH
   
  As for the single-tube alternative, I've never looked into it, but I did see a similarity between that and the cheap chinese "open" tube hybrids you find on eBay. One of them had a single 12AU7 driving two channels and IRF510 mosfets, so I figured the schematic was probably very similar. I have no idea how they sound, though.
   
  Good luck building! The main SSMH thread is a great resource and a lot of pertinent info can be found in it if you search around a little bit. It can be daunting at first but take it slowly and eventually you'll know the project like the backside of your hand.


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## TestSubject

Here is my version 2.0 with 2 different layout (2.01 and 2.02)

  V2.01:

  V2.02

   
  One question, on a Perf board, how many leads can we put in the same hole? To solder 2 resistor together for exemple.

   
  Thanks!


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## digger945

You can get stripboard with any number of connected pads. http://www.futurlec.com/ProtoBoards.shtml
  You could also use a terminal strip or turret board.  http://angela.com/connectors.aspx
  I use euro strips a lot for prototyping.  http://compare.ebay.com/like/350115300106?var=lv&ltyp=AllFixedPriceItemTypes&var=sbar&_lwgsi=y


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## TestSubject

Quote: 





nikongod said:


> I found this on a quick google images search for "12au7 starving student schematic"


 

 This is the schematics i used.


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## TestSubject

I wish someone would confirm that im following the right schematics... Also are the "Optional" components worth it SQ wise?
   
  EDIT: The design is the same except for the "Optional" stuff and for the values of other components. I Havent bought anything yet. if the new one is better, where can i find a BOM?


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## TestSubject

This is not much but i feel proud somehow, the more i do this, the more i realise that a sripboard design might actually be better / less messy.
  Hope to get feed back


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## Ikarios

Most of the optional components are, in some people's opinions, necessary (like R14/15, 16/17). The main one you can do without is C7/C8, since that doesn't necessarily improve SQ very much. You can try searching for info but I don't think there's very much about it besides the fact that they increase gain (by reducing feedback, I think). You could probably do without C3a/5a but those are film bypass caps so will probably improve the sound. You can find a BOM on the DIYForums page, making sure to swap out the necessary changes for 12AU7 (resistors). http://www.diyforums.org/SSMH/SSMHbom.php


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## nikongod

Quote: 





ikarios said:


> The main one you can do without is C7/C8, since that doesn't necessarily improve SQ very much. You can try searching for info but I don't think there's very much about it besides the fact that they increase gain (by reducing feedback, I think).


 

 These caps reduce internal feedback in (around?) the tube and frequently result in more gain, but more importantly adding them reduces distortions. Kind of paradoxical, since people normally think of feedback as the great distortion destroyer.
   
  In any event, putting them in/taking them out is just a few solder joints away. Experiment!


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## kchapdaily

do the newer additions work/benefit with the original 19j6 tubes?


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## TestSubject

Anything on my Perfboard design? i will make the adjustments with the new components. Any BOM available for the 12AU7 version?


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## TestSubject

Stripboard version:
  Note that the orange pad is the 4th pin of the tube.
  Also, i realise i forgot to add the "Optional" components...
  Long jumper might be replaced by cables.
  By the way, how big are the Caps? i always draw them small but...
   
  I would be nice if someone checked it, maybe after i add the missing components.


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## TestSubject

V3.1:


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## kchapdaily

you may have to work on spacing of components. if you use wima caps for C2 and C4 in the original schematic, there leads wont fit in that configuration. also depending on what kind of electrolytic caps you use you may need more room. i used big 100v (digikey didnt have 63v and i wasnt comfortable with 50v) nichicon muse kz's on mine and the leads are fairly far apart. same for resistors.
   
  its good to plan your build out like this, but im sure you could draw the schematic from memory by now
	

	
	
		
		

		
			




  my advice is just go for it. just check your work as you go.


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## TestSubject

Quote: 





kchapdaily said:


> you may have to work on spacing of components. if you use wima caps for C2 and C4 in the original schematic, there leads wont fit in that configuration. also depending on what kind of electrolytic caps you use you may need more room. i used big 100v (digikey didnt have 63v and i wasnt comfortable with 50v) nichicon muse kz's on mine and the leads are fairly far apart. same for resistors.
> 
> its good to plan your build out like this, but *im sure you could draw the schematic from memory by now*
> 
> ...


 
   
   
   

 [size=medium]Hehe Pretty much
   
  Thanks for those kind words, im working on this a lot because im new to electronics and i want things to work. The High school theoretical stuff is now very useful but never taught i would have to design boards so early, not that this is a complex design but coming from a Cmoy where it is Step by Step... A picture of your build to see the size of the Caps would be good, im a visual guy you see.
   
  I wish someone would take the time to check my board but it is asking a bit much i guess... if this works i will make a tutorial to help people like me who wants to make a SSHM but hate messy wiring.
   
  On another note, I made a BOM because i could not find one for the 12AU7 version.
   
  1/4 Watts Metal Film Resistors:
   
  2: 1K
  7: 2K
  2: 33K
  2: 50K
  2: 220K
  2: 390K
   
  Capacitors (need help finding what kind of caps):
   
  4: 0.22uF
  2: 470uF
  2: 680uF
   
  MOSFET:
   
  2: IRF510
   
  PSU:
   
  1: 48V 0.38A (need help finding one, i know the Cisco one eBayLink was popular back then but what about now)
   
  Other:
  1: 50K Stereo Potentiometer
  2: RCA Jacks
  1: Switch
  1: Power Jack
  1: 6.5mm Phone Jack
   ​[/size]

  Thanks


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## Ikarios

I'm not sure there's an alternative for the PSU, unless you can find something that fits the specifications (48V, 0.38A or above). The Cisco PSU is still cheap on eBay, so it's pretty hard to beat. There is the issue of the DAC-killing thing, though, which is most likely the fault of the PSU.


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## kchapdaily

ill put some pictures of mine up tomorrow. its currently caseless im still working on that.
   
  as for the capacitors, generally your going to want the .22uf caps to be wima's http://beezar.com/catalog/product_info.php?cPath=24&products_id=73
   
  the other values are going to be electrolytics. the nichicon muse es or kz caps sound great and are widely used for this amp.
   
  i use the cisco power supply, but my amp uses 19j6 tubes.


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## digger945

Quote: 





testsubject said:


> V3.1:


 


  Do you intend to use this exact kind of stripboard? If so, then all of your caps are shorted out except C1's. Perhaps you could begin by focusing on establishing a strip in the middle of the board for ground, and the 2 outermost strips for power(B+). Be flexible. If you need 2 strips for ground then use what you need.
   
   
  If you study the schematic, you will notice that there are no more than 3 or 4 items attached to any single node, excluding ground.


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## TestSubject

Quote: 





digger945 said:


> Do you intend to use this exact kind of stripboard? If so, then* all of your caps are shorted out except C1'*s. Perhaps you could begin by focusing on establishing a strip in the middle of the board for ground, and the 2 outermost strips for power(B+). Be flexible. If you need 2 strips for ground then use what you need.
> 
> 
> If you study the schematic, you will notice that there are no more than 3 or 4 items attached to any single node, excluding ground.


 
  Well no, you cant see because it is under the caps, but the strip i cut in between like all the horizontal resistors.
   
  Thanks a lot for having a look at my design, if anything else is wrong please point it out.
   
  EDIT: Sorry, but with all that copy and past (not very good version of diylc) the marking on the resistor and caps are wrong, R1 is not the schematic R1 for exemple. I will fix it soon.
   
  Changed opacity of the caps so you can see:


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## nikongod

I generally prefer NOT to waste too much time thinking about perf-board layouts until the parts are in my hands. Nothing ever fits the way I think it will if I really plan it out. For example none of the caps on your board have adequate room for leads or bodies.
   
  None of the part numbers match from schematic to layout. (i started typing this before you edited that in.)
   
  No connections to stuff off of the board are marked. Demerit. 
   
  R6 on the lower half of the board does not connect to the junction of R3/R4 like it does on the top half. 
   
  R4 in the middle of the board looks like the gate stopper resistor for the mosfet. The gate stopper should ideally be soldered as close to the mosfet as possible - much better to save some board space and air-wire it with the body of the resistor right up against the mosfet's pin. 
   
  Why are there 2 sets of connections below R2? Im guessing these are for the various parts of the tube (top plate, middle grid, bottom cathode), if so its much better to solder the various parts of the tube together at the tube socket rather than using double the wire. If your careful about it point to point work can be very beautiful.
   
  Is the left R4 (thats the R4 near the left edge of the board, not left channel) the tube grid stopper resistor in the improved schematic? Much better to solder it directly to the tube socket.
   
  It looks like all 3 connections to the mosfets are on the board. You will not (I seriously hope not anyways) be putting the mosfet directly on the board - feel free to put those connections anywhere you want. This applies to the doubled-up tube connections too. 
   
  The C3 caps look like output caps. They are connected to the gate of the mosfet, not the source. 
   
  If you rotate the c3 caps 90* so the output is on the bottom of the board rather than on a horizontal like now you can save yourself the trouble of cutting a few traces and adding jumpers


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## TestSubject

Sorry i have been busy lately,
   
  Here my new version. V3.3


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## zammykoo

Looks very interesting, TestSubject.
   
  I plan on making a pcb for my own build, but if that doesn't pan out I'll try the protoboard route.


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## TestSubject

@ NikonGod, Thanks a lot! 
   
  @Zammykoo Well hope that my layout will help you if you choose the Protoboard way.
   
  Here is V3.4:

   
  Hope to get building soon!


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## Ikarios

As a quick note, as nikongod said, you may have trouble fitting your capacitors onto a stripboard like that. I would first pick out the caps you're going to use (or better, buy them first) and look at the datasheets so you can see what their lead spacing is and plan/make changes accordingly.


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## TestSubject

Quote: 





ikarios said:


> As a quick note, as nikongod said, you may have trouble fitting your capacitors onto a stripboard like that. I would first pick out the caps you're going to use (*or better, buy them first*) and look at the datasheets so you can see what their lead spacing is and plan/make changes accordingly.


 

 Buying this week.


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## Fred_fred2004

Quote: 





testsubject said:


> @ NikonGod, Thanks a lot!
> 
> @Zammykoo Well hope that my layout will help you if you choose the Protoboard way.
> 
> ...


 


 Sorry the pots are wired wrong the wipers should go to the amp
   
  cheers
  FRED


----------



## TestSubject

Thanks! here is V3.4.1:


----------



## DarkWinter

This looks Great I might make one depending on how yours turns out XD


----------



## TestSubject

Sure this is the reason i post here to help people like me who want a Stripboard design instead of p2p.


----------



## digger945

The little squares with red dots are supposed to be cuts in the traces?


----------



## TestSubject

Yes that's right.


----------



## digger945

Assuming the bottom pins on the mosfets are Source, then the top pins would be gate.
  Top to bottom.....
  Gate
  Drain
  Source
   
  You can just swop the wires if we want to understand that the drawing is not correct.


----------



## digger945

R8, 390k from +48v to the lower mosfet Gate(assumed the center pin on the drawing)


----------



## digger945

R7, 33k from +48v to the plates of lower 12au7(pins 1 and 6)
   
  We can assume that the traces will be cut beneath C2 and C4 before mounting.
   
  Move C5 and C5a down one pin, so they couple the lower mosfet source pin with output Right.


----------



## digger945

The little squares with red dots to the far right, next to the output. 
  Move the upper one up one trace.
  Move the lower one down one trace.
  So that they are blocking/terminating the trace with the center pin on the mosfets.


----------



## digger945

R6 should be connected directly from Ground to the left output.
   
  R12 missing, should be same 2k directly fro Ground to right output.


----------



## digger945

Ok, why don't you redraw and we can take up the rest of things tomorrow. I gotta hit the sack for tonight.


----------



## TestSubject

Sounds great thanks again!


----------



## zammykoo

Wow, stripboard layouts seem harder to follow than pcb, but I look forward to seeing the revised design. Looks like you got this round taken care of.


----------



## TestSubject

Hello,
   
  I Havent been very well for the past week, but here is an update, I am about to order the components
   

  A couple things are bugging me, for one, the price, 63 Euros, thats about 90$.
   
  2) of all the recomanded brand for caps only wima was available, is it worth it sice i cant get the other good brands?
   
  3) 33k Ohms resistors are only available at 1/2 watts
   
  4) no 50 K available
   
  5) MOSFETS IRF510 are not available, any alternative?
   
  6) only stereo 50 K Pot is at 17 euros/ 25$ i mean really? looks good but...

   
  The Psu and tube sockets are ordered.


----------



## kchapdaily

the total price is pretty high. you cant order from mouser or digikey?
   
  as for the caps, you definitely want wima for the output bypass caps, and they are good for the coupling position.
  does the place your ordering from not carry nichicon capacitors?
   
  and you kind of want a high quality potentiometer. if you think about it, its really the first component that comes into contact with the signal that could introduce noise. alps are good, but there are lots that are even better.


----------



## TestSubject

Hey
   
  Thanks for that but concerning the Mouser/digikey stores, the problem is that i live in France so i have to pull up with the super high prices.
   
  Hope someone could review my previous post to make sure everything is fine.
   
  Thanks


----------



## kchapdaily

as far as i can tell it looks correct. your getting 100 each for resistors? 
   
  also its ok to use 1/2 watt resistors. you can get higher tolerances without a change in performance, you just cant get lower tolerances, for example 1/8 watt


----------



## digger945

It is good to see you are feeling better Pierre.
   
  I wanted to quote the schematic below just to make sure we are all on the same page.
   
   


  Quote: 





testsubject said:


> I wish someone would confirm that im following the right schematics... Also are the "Optional" components worth it SQ wise?
> 
> EDIT: The design is the same except for the "Optional" stuff and for the values of other components. I Havent bought anything yet. if the new one is better, where can i find a BOM?


 


   


  Quote: 





testsubject said:


> Hello,
> 
> I Havent been very well for the past week, but here is an update, I am about to order the components
> 
> ...


 

 47k resistor? I don't see it on the schematic.
   
  There are lots of different kinds of Wima caps(I noticed you have a 1600v part in your cart, which will cost a lot more than something like a 63v part, which will work fine here). You can look for a cheaper one(any voltage rating 63v and higher) or just substitute something else, like Epcos or anything with close to the same uF/nF value. It doesn't need to be a box cap, it can be radial or axial leaded. You don't even need it at all and could omit it for now, and install one later if you want.
   
  The half watt resistor for 33k will be fine.
   
  The mosfets will be dissapatind around 5.5watts so they should have a fairly good heatsink. 
   
  I don't know what to say about the volume control pot. Perhaps look at a Panasonic for some alternatives.


----------



## kchapdaily

Quote: 





digger945 said:


> 47k resistor? I don't see it on the schematic.


 

  
  testsubject said 50k resistors are out of stock at that shop


----------



## digger945

Quote: 





kchapdaily said:


> testsubject said 50k resistors are out of stock at that shop


 


   
  I do not see 50k on the schematic either.
   
  You could substitute an IRF610 if you can not find an IRF510 anywhere.


----------



## kchapdaily

look right after the left and right rca input


----------



## digger945

Quote: 





kchapdaily said:


> look right after the left and right rca input


 


   
  Oh. Those 50k 
	

	
	
		
		

		
			




   
  At first glance I hesitate to say that they are necessary at all. 47k would be fine as a substitute.
   
  Pierre, do you have TO220 insulator pads and screw mounting bushings for your IRF parts?
  Insulator pads, etc. -> http://www.google.com/search?rlz=1C1GGGE_enUS357US359&sourceid=chrome&ie=UTF-8&q=to220+insulator#q=to220+insulator&hl=en&rlz=1C1GGGE_enUS357US359&prmd=ivns&source=univ&tbm=shop&tbo=u&sa=X&ei=QSE_Tq79F4-DsgKjx9AS&ved=0CFQQrQQ&bav=on.2,or.r_gc.r_pw.&fp=c15b6bc10f253e42&biw=1280&bih=709
   
  Mounting bushing(part E or F to fit your part) ->  http://www.cpcares.com/pdf/1610.pdf


----------



## kchapdaily

id say use mousers to220 mounting kit but thats out of the question. 
  you definitely need a mounting kit that has nylon (or some other non-conductive material) shoulder washers otherwise your heatsinks may become attached to ground which could cause problems. just search whatever site your using for parts for a to-220 heatsink mounting kit.
   
  @digger945
  i think the 50k resistors help maximize the volume pots effectiveness. you could take them out and use an 100k pot but you would have to use the later 150degrees of rotation.


----------



## digger945

Quote: 





kchapdaily said:


> @digger945
> i think the 50k resistors help maximize the volume pots effectiveness. you could take them out and use an 100k pot but you would have to use the later 150degrees of rotation.


 


  Ah yes. So the pointer on the volume knob looks more presentable. I understand why some would like to see it at noon rather than 7 o'clock. 
   
  I can send the mounting hardware if necessary. I will see if what I have on hand will fit the tab holes for the IRF parts.
   
   
  EDIT: ... and yes, you are correct that you will have a little more precise setting on the volume control.


----------



## TestSubject

Thanks a lot digger945 for reviewing V3.4, here is 3.5:
   

  I cant thank everybody here enough for all the support you are providing! You people are amazing really!
   
  I really hope that the work we are doing here will help others making a SSHM. I know it is a fairly simple design but when you are new to electronic like myself you like soldering components on boards, makes the process a all lot easier in my opinion.
   
  Also thanks for pulling up with my engrish.
   
  EDIT: Ho and i got a pair of DT-770 Premium 250Ω cant wait to amp it up! The Cmoy i have sounds horrible with it.
   
  Pierre


----------



## zammykoo

Pierre, good to see you are back.
   
  I am at work so didn't really get a chance to review your circuit revision for correctness, but one thing I noticed right away was that your tube socket's traces are incorrect (bridging pin2 to pin7 and pin3 to pin8). If you look at the schematic again, the numbering is not in the right order from 1 - 8. It flips at #6. I'll check the rest of the traces tonight when I get home.
   
  Also nice choice of headphones, I have been wanting a dt770 as well, I may pick one up too.


----------



## zammykoo

I just had a chance to review the latest revision. There are a couple things I spotted that needs to be looked over:
   
  - R1 & R2 are not supposed to be connected to Q1's drain (pin2)
  - I suppose you are not including caps 7 & 8?
  - Also in my last comment, I mentioned the unordered socket pins on the starving student schematic... I do realize your schematic's socket only has 8 pins (instead of 9) as well. Maybe you intentionally drawn lines that way knowing that you can always cross the wires on the production model.
   
  Hope that helps!


----------



## TestSubject

Thanks for having a look, now that 9th pin has been bugging me, first it is not on the schemtic so I dont know what to do with it. I will have a look at the data sheet and report back.

Yes i chose to get rid of caps 7 and 8 but it is a little stupid because i have no real understanding of what those 2 caps are for. I think i was just lazy.

I have been shopping for parts but the website i shop from had difficulties working properly, so i will keep you posted on my progress.

Just making sure that 1/2 watt resistor can be used instead of a 1/4 watts. I mean it makes sence, but better be safe than sorry.


----------



## zammykoo

As far as pin9 goes, on the SS schematic it should be the dip in between pin4 & 5, which is not being used. I'm not exactly sure what it does though. If you look on my pcb design you can see how the traces are connected within the socket pins. http://www.head-fi.org/forum/thread/565483/12au7-starving-student-custom-pcb-drawing-critique-please#post_7653338
   
  For caps 7 and 8, I would just put them in there. Dsavitsk and Tomb advised me to just go with all of the optional components since they are fairly cheap and will definitely help. And for the resistors, the larger the watt, the safer. You are just sacrificing a larger physical size.


----------



## kchapdaily

im pretty sure caps 7 and 8 are to help with noise floor, but if you use the right cap (nichicon muse es for example) it improves the sound, especially bass handling. id put them in there its maybe 2$ more in parts.
   
  as for the resistors, 1/2 watt will work absolutely fine. they are considered overkill, but there only detriment besides cost is that they are physically larger. 1/4 watt is still on the safe side, there cheaper (not by alot, but still) and their smaller. size isnt a big concern as you are not using a production board, but if you were, you would need the 1/4 watt resistors becasue 1/2 wouldnt fit on the board.


----------



## jdkJake

C7 and C8 are decoupling (or bypass) capacitors. They decouple the signal being developed across R5 and R11. They are pretty important and a basic element to the design of the amplifier.


----------



## TestSubject

Okay here is 3.6, Hope i solved everything you mentioned! Worked a bit on the layout so it would be cleaner. Hope the arrows are not in the way.

   
  @digger945 i promise to work on buying parts as soon as the website is working!


----------



## kchapdaily

looks good! i think its ready! just remember you need to take r3 and r9 off the board and attach them to the leg of the mosfet. you want them as close as possible.


----------



## digger945

Could you give a link to the power supply you will be using?


----------



## TestSubject

Thats great news!
   
  Sure here is the link for the PSU: LINK


----------



## TestSubject

Website back Online! Did this very quickly, and i cant find the proper resistances... Will it be okay? (Cant buy 1/4 Watts resistors other then in packs of 100)
   
  Will add all the other components tomorrow. Ho and if you could have a look at the Caps.
   

   
  PS: can go lower or higher but no 2K or 50K
   
  Thanks


----------



## kchapdaily

i dont think it will be a problem. this amp is not super sensitive to resistance. you could also use 2 1kohm resistors in series,
   
                 Rtot=R1+R2+R3...


----------



## digger945

On your previous order you had 1/4 watt 2k ohm resistors shown. Now everything is 1/2 watt. Either one would be fine, or like kchapdaily mentioned you could use 2 or the 1k in series, or 2 of the 4k parallel.
   
  From where are you ordering parts in France?


----------



## TestSubject

Ho yes i forgot i had found a 1/4 Watt 2K ohms resistor. 47K instead of 50K would be fine? I mean i could 47+3 but is it worth it?
   
  I am ordering from http://www.conrad.fr
   
  EDIT: if you happen to know a better one please let me know!
   
  Thanks


----------



## TestSubject

Got an enclosure (Rather large Wooden Cigar Box) and a computer heat sink with possible fan.


----------



## TestSubject

VERY quick sketch for a 1 tube version:


----------



## zammykoo

You can share one tube for both channels in this amp? I didn't know that.
   
  Cool cigar box by the way, looks like you would be able to include a built in dac in there too!


----------



## kchapdaily

im not sure if those heat sinks will be suitable. is there a hole or bracket for mounting a to-220 part? if not i recommend buying a heatsink designed for to-220 parts.


----------



## Ikarios

Quote: 





jdkjake said:


> C7 and C8 are decoupling (or bypass) capacitors. They decouple the signal being developed across R5 and R11. They are pretty important and a basic element to the design of the amplifier.


 

 They are not a basic element to the design of the amp, Pete didn't have them implemented in his original design. They were added in when dsavitsk (I believe) added in his improvements, and can be left out. I know for a fact that Beftus had at least one SSMH where he disconnected C7/C8, he noted that it reduced the overall gain but otherwise didn't change too much.
   
  As for pin 9 on 12AU7, it is used for a center tap (instead of 12.6V, 6.3V) and can be utilized in some single-tube designs (like the Bravo amps on eBay). We don't need it here so it's not connected to anything.
http://en.wikipedia.org/wiki/12AU7


----------



## jdkJake

ikarios said:


> They are not a basic element to the design of the amp, Pete didn't have them implemented in his original design. They were added in when dsavitsk (I believe) added in his improvements, and can be left out. I know for a fact that Beftus had at least one SSMH where he disconnected C7/C8, he noted that it reduced the overall gain but otherwise didn't change too much.




I stand corrected on the caps being part of the original design. Must be the starving part that reduced the parts count. 

That being said, those caps are still a good idea. There is a signal being formed across the cathode bias resistors that is in phase with the input signal to the grid. This is a form of negative feedback that the capacitors eliminate. This is also why the gain goes down when the caps are eliminated (introduction of negative feedback reduces overall gain).

Perhaps it might be worth experimenting to see which sound is preferrable.


----------



## jdkJake

zammykoo said:


> You can share one tube for both channels in this amp? I didn't know that.




You could, but you probably would not want too without making additional component value changes.

Paralleling the triode sections doubles gm (current gain) while keeping mu (voltage gain) the same. The rp (plate resistance) is also halved. So, you would want to account for all of this in the final parts selection.


----------



## nikongod

Quote: 





testsubject said:


> VERY quick sketch for a 1 tube version:


 

 As others have said, be sure to adjust the voltage divider resistors (the resistors from 48V to ground, with the signal in the center) to accommodate the new heater voltage. 
   
  The output caps are still hooked up to the gates of the mosfets - they should be hooked up to the source.
  
  Quote: 





jdkjake said:


> gm (current gain)


 

 Just nit-picking, but Gm is not current gain, it is transconductance - the change in current through the tube or transistor when the input signal is changed by 1V. It does double when the sections are paralleled though 
   
http://en.wikipedia.org/wiki/Transconductance
   
  Current gain is literally output current/input current.


----------



## TestSubject

Trying to finish my BOM:

  The caps:


----------



## TestSubject

Are the BUZ 20 Mosfet okay for an alternative to the IRF510?


----------



## TestSubject

3.6.1:


----------



## kchapdaily

Quote: 





testsubject said:


> Are the BUZ 20 Mosfet okay for an alternative to the IRF510?


 


  i dont speak french so im not sure what some of that stuff means, but they look like a suitable replacement. can someone confirm this? i dont have my bom in front of me im on vacation


----------



## digger945

Quote: 





kchapdaily said:


> i dont speak french so im not sure what some of that stuff means, but they look like a suitable replacement. can someone confirm this? i dont have my bom in front of me im on vacation


 


   
  It looks similar in most ways, except about 3 times the Gm(transconductance) and about a third of the Rds on resistance. The transfer curves are not the same, but both the BUZ20 and IRF510 show most ratings in the amps of current, when we are dealing with about 150mA here. I would say if you can get a pair of them cheap, go for it. I would love to have one to test. 
   
  Let me look at the datasheets for a few more minutes.


----------



## digger945

I like the way the BUZ20 looks on paper, but recent experience has shown me that these mosfets can vary alot in how much heat they can dissapate from one part to another. 
   
  Without having worked with these devices, I am going to have to recommend that you stick with the IRF510 or IRF610. 
   
  Can you give a link to the BUZ20 parts that you are looking at?
   
  If you are having a hard time finding the 510 parts, then I will help you out there, and mail you whatever parts that you need.


----------



## TestSubject

Thank you much digger945, but i dont want to abuse your generosity. I ordered the proper Mosfets from ebay.
   
  If anyone can help me with C7/C8 that would be great. Also i hope to finish my BOM to order today and get free shipping.
   
  EDIT: Forgot i had that: LINK
   
  REDIT: is 51K okay for R16/R17?
   
  Thanks again everyone


----------



## digger945

My offering to send parts is no different than I have done for many others 

For C7/C8 I would definitely use the parts on the schematic, which is 220uF 16v.

You could use a higher voltage rated part if 16v is not available at your supplier.


----------



## digger945

For R16/R17 you could use the 47k that you had before or the 51k, it would not matter at all.

The BOM that you linked to above is for the 19J6 amp. There are a couple of differences in parts values.


----------



## kchapdaily

you could order your c7 c8 from beezar. they have 220uf 16v nichicon muse es's


----------



## TestSubject

This is how R3/R9 should be right?
   
  3.6.2:


----------



## digger945

Quote: 





testsubject said:


> Trying to finish my BOM:


 
  Is this your final shopping cart?
   
  Are the resistor amounts still 100 pcs, or the Qte to the left of the page? ... if so then you will need to change...
  2 pcs of the 1k resistor
  2 pcs of the 220k resistor
  2 pcs of the 390k resistor
  2 pcs of the 33k resistor
   
   ... and add...
  2 pcs of the 220uF 16v. These can be Nichicon Muse ES, or Sanyo OSCON. If those are not available then we can take a look at something else.


----------



## digger945

Quote: 





testsubject said:


> This is how R3/R9 should be right?
> 
> 3.6.2:


 

  
  Yes. R3 and R9 go the the gates on the IRF510 (pin 1 or the left most pin if the part is facing you with the legs down) 
   
   
  You are missing R2 and R8 for the mosfet bias. Apologies if you are not finished yet.


----------



## kchapdaily

Quote: 





testsubject said:


> This is how R3/R9 should be right?
> 
> 3.6.2:


 


  yes
   
  edit: oops didnt see digger already posted


----------



## TestSubject

I have labeled R2/R8 is this okay?


----------



## digger945

Quote: 





testsubject said:


> I have labeled R2/R8 is this okay?


 
  Yes.


----------



## zammykoo

Yep, what he said.
   
  Pierre, I dont know if you wanted to keep the bypass caps, but should add to the list if possible.
  
  Quote: 





digger945 said:


> Is this your final shopping cart?
> 
> Are the resistor amounts still 100 pcs, or the Qte to the left of the page? ... if so then you will need to change...
> 2 pcs of the 1k resistor
> ...


----------



## TestSubject

i did try to reply earlier but i guess it didnt work. I am having trouble ordering what i want, i am calling an electronic store tomorrow and speak my way out of this. i dont understand why French store wont work but so far nothing has worked out the way i wanted. Seems like they have very small inventories. Bigger stores are USA/UK based and charge to much for shipping.
   
  I will keep you posted but thanks again
   
  EDIT: Today everything was closed will try tomorrow


----------



## TestSubject

Here is a quick update, i have been trying to order the part online here in France and is has been a real nightmare (no it's not laziness), Digger945 has kindly agreed to send me the parts from mouser.com as mouser.fr asked 30$ for shipping.
   
  I need a soldering iron, I might as well invest into a good one, i found this  Weller wtcp-s second hand but looking almost new for 120$ what do you think?
  Can probably go a bit lower if i bargain here is the LINK

   
  Thanks everyone for showing so much support and i hope that the next post will be pic of my build in progress.


----------



## kchapdaily

a good soldering station is very important. i have an aoyue 937+ and i highly recommend it. its a good quality hakko clone and it performs very well. not sure how much it would cost in france, but i got it for 60$ shipped in the us. heres the link
http://www.amazon.com/Aoyue-937-Digital-Soldering-Station/dp/B000I30QBW/ref=sr_1_1?ie=UTF8&qid=1313982476&sr=8-1
   
  i dont have any experience with weller stations but they seem to have great reviews.


----------



## TestSubject

What i have so far:

  1: Large Wooden Cigar Box
  1: Cisco PSU with the wrong plug for my country (not a problem but funny since it comes from china).
  2: Ceramic tube socket.
  2: Mosfet
  1: "Super" computer heat sink with possible fan.
  1: Bad picture
   
  Will the computer heatsink be enough? Will it work if i just drill a hole and bolt the Mosfets to it with termal paste? Wooden box so no Ground problem.
   
  EDIT: Here is a better picture of the sockets i got from eBay:


----------



## kchapdaily

heatsink should work it looks large enough. nice choice for the enclosure! i like it


----------



## jdkJake

Quote: 





testsubject said:


> Will the computer heatsink be enough? Will it work if i just drill a hole and bolt the Mosfets to it with termal paste?


 

 What is the dissipation rating for the heatsink? Size and shape alone are not an indication of performance.
   
  Are you still going forward with a single tube implementation?


----------



## TestSubject

I am sorry, i do not know the dissipation rating, i got it from a computer i found in a dump while looking for parts in my quest into making a jet engine.
   
  It is a CPU heat sink, it should, in theory be fairly good quality,(came with a fan if needed) but that is not very scientific i agree.
   
  I would like to try the one tube version, should help not having to "match" tubes plus it is overall less expensive.
   
  However, i am afraid i dont have the competence to modify the design that will match the single tube modification.


----------



## jdkJake

Now I am more curious about the jet engine! 

Must be one heck of story behind that DIY!!


----------



## TestSubject

Ever dreamed of driving a batmobile?


----------



## kchapdaily

buying individual heatsinks for each mosfet would possibly be more effective, if digger is sending you the parts why dont you add those to the list? there very cheap only about 1$ each. that way you dont have to guess whether or not your heatsink will dissipate enough energy


----------



## TestSubject

Sounds Good thanks. An model in mind from Mouser?


----------



## kchapdaily

567-657-15ABP
  thats the standard starving student heatsink spec'd by pete.


----------



## jdkJake

testsubject said:


> Ever dreamed of driving a batmobile?




But of course! 

BTW, I am not saying that heat sink will not work, just be cautious. The wood case will not provide any thermal assistance as a metal case would. Most CPU heatsinks are designed for size and reach their performance by using a fan, which, you really want to avoid in this application. Since you will be externally mounting the sink, it might be perfectly suited for the build.

Besides, I like the whole repurposing aspect of using it. It looks good as well.


----------



## TestSubject

Got my tubes:
   

   
  Got both for 8$ Not tested salvage from old electronics. A bit worried that they wont work...
   
  Plus the probably wont "Match" sound wise right? Also on is VII-7 and the other is IX-3.


----------



## TestSubject

About the Heat sink, i looked on mouser for an alternative that would lay flat and bolted to the back of the case (I dont really like them sticking out the top with the tubes) but i had no luck.
   
  Any ideas?


----------



## zammykoo

The tubes may work fine, I mean you might as well test them (once your amp is built) since you have them already.
   
  I have also wanted to drive a batmobile


----------



## TestSubject

Would someone consider taking the time to modify the design for a single tube version of this since one full tube is used per channel.
   
  I made a very quick sketch just to illustrate the idea but again i am not qualified enough to make this work. Pay only attention to the cabling, I know the layout of some of the components is wrong and everything should be fixed up in Rev 3.6.2
   

   
  Rev 3.6.2(Could use someone checking again the layout. Cant thank you people enough):
   

   
  And here is the schematic (why not?)


----------



## digger945

This particular amp would need some changes to really have something that would work well. 
  Something like one of the following amps...
http://diyaudioprojects.com/Solid/Tube-Mosfet-Hybrid-Headphone-Amp/
  or
http://diyaudioprojects.com/Solid/12AU7-IRF510-LM317-Headamp/
   
  ...where the heater string is removed from the output series, and just used "normally."
   
  I can't seem to find the reference where I was reading about it(Beezar maybe?), but suffice it to say that just dropping 6v(using the center tap on the 12au7 heater) on the output string(while still retaining the 48v power supply used here) would be a bit much on the mosfet. It would make a good project to learn more.


----------



## dkong

Hey TestSubject, any updates of your project yet? I like the work you've done so far. I am not currently concerning myself with construction of a starving student amp, but I like those stripboard drawings you made. What software did you use?


----------



## zammykoo

Quote: 





dkong said:


> Hey TestSubject, any updates of your project yet? I like the work you've done so far. I am not currently concerning myself with construction of a starving student amp, but I like those stripboard drawings you made. What software did you use?


 
   
   
  I believe he is using diylc


----------



## TestSubject

People, I am not dead, something happend to me though, School happend.
   
  Got all the parts right here (BIG thanks to digger945) but time is an issue right now. Like many people suggested i need to review my layout since the caps are big (doing that now)
   
  Anyone had problem with DIYLC crashing 2-3 times every minutes (MAC)? Makes things very hard as you might imagine.
   
  Will keep you posted.


----------



## kchapdaily

what version are you using? i have 3.0.9 and it seems to be working fine


----------



## ictin

Quote: 





testsubject said:


> People, I am not dead, something happend to me though, School happend.
> 
> Got all the parts right here (BIG thanks to digger945) but time is an issue right now. Like many people suggested i need to review my layout since the caps are big (doing that now)
> 
> ...


 

 I had it crashing in Linux also, but not so often. Was crashing every 10 minutes, but without crashing it getting unusable after a few minutes (i can modify some values because the drop box is disappearing or other strange thing happens)


----------



## BangDead

Hi guys. I just made an account to ask a question here as i'm confused... I like the awesome strip board layout and may be using it to make mine. Looking at the REV 3.6.2 and comparing with the schematics, isn't the R6 and R12 supposed to be connected between line out and ground? Thanks in advance..
   
Update:
  I've copied the REV 3.6.2 and made another one with a few changes to confirm i'm reading your layout right.. I'm not so sure about this because i'm just a newbie but i'm willing to learn so, if you see any problem, do tell me. Thanks.
   

  [Click image to enlarge]


----------



## TestSubject

Hello everyone,
   
  3.7 is here this time with proper scale. 3.7.1 will be more detailed. DIYLC was very annoying, crashing non stop. The Windows version seems to be better.
   
  Cant wait to solder everything up
   
  Thanks BangDead Fixed R6 R12
   
  If anyone cares to check the design to make sure, that would be good.


----------



## TestSubject

@BangDead How is Design going? Looked at my 3.7 yet?
   
  Should get soldering soon, need some stripboard, what i had left is not big enough...
   
  Also 3.7.1 Coming soon. Anyone still with me?


----------



## TestSubject

So it begins, Nothing can stop me now.


----------



## digger945

R3 and R9 will be soldered very close to the MOSFET gates?
   
  Looking good.


----------



## TestSubject

No worries, they will be soldered directly on the gate pin.
   
  Thanks


----------



## TestSubject

Its coming along ok. Except I got mixed up in some capacitor size, after a little shuffling around, back on track.
   

   
  God like soldering skills (not really, thick soldering wire doesnt help.)


----------



## TestSubject

Looks like I am done with the circuit.
   
   

   
  Next the box.


----------



## TestSubject

I am a little confused on the type of wire i should use for the Transistors, Would ruban cable work?


----------



## digger945

Anything around 24 gauge or bigger should work fine for the source and drain. Smaller stuff would be ok for the gate.


----------



## TestSubject

A first review of the completed box:


----------



## TestSubject

Any tips on how to add some LEDs under the tube circuit wise?
   
  Also:
   

   
  Case need to be varnished and the external components needs to be soldered in, I should be done sometime today.


----------



## nikongod

Quote: 





testsubject said:


> Any tips on how to add some LEDs under the tube circuit wise?


 

 If your sockets have the little holes through the center the common practice is to stick the LED's in the holes and wire them and their resistors in.


----------



## TestSubject

And its done, everything is wired up and double checked. When i plug it in, with a source active, nothing happens, no sound nothing glows inside the tubes, nothing at all. A little annoyed.
   
  Is there any ways to check if the tubes are OK?
   
  Checked conductivity between pin 4 and 5, and nothing.
   
  EDIT: 9 and 4, 9 and 5 conducts


----------



## digger945

Some of the power supplies struggle a little to fire up a cold amp, so the power supply may cycle on and off a few times until the heaters get hot.
   
  It takes the heaters more than a few seconds to get hot enough to warm the cathode sufficiently to begin emitting electrons, completing the circuit and allowing you to hear music.


----------



## TestSubject

Ok thanks, I am turning it on right now, ill wait a couple of minutes and see... I mean hear how it goes.
   
  Ill keep you posted.
   
  EDIT: After a good 20 minutes still nothing.


----------



## digger945

You double check the pinout on the mostest? The pinout on the devices does not match the pinout on your board.


----------



## TestSubject

I wired the mosfets following the schematic not using my design as they were just there for demonstation. Checking again now just to make sure.


----------



## digger945

If you are facing the part, the pins would be gate drain source, from left to right.


----------



## TestSubject

Like so right? then it should be fine. However, i spotted a mistake on my board, a jumper that wires the Drain to power is not placed properly,  however the other channel should be ok... Yet nothing.
   
  EDIT: Fixed the Drain and fixed one tube wired wrong... man I know I should have went to bed instead of trying to rush the build. Hope nothing is blown. Still no sound
   
  EDIT: PSU running at 65Volts... What is going on...


----------



## digger945

Check some voltages. Start at the power inlet.  Make sure the polarity is not reversed.
  My first guess would be cold solder joints.


----------



## TestSubject

Could you indicate on the design some useful place to probe for voltages? I test for conductivity after each solder joint I make.


----------



## digger945

how about pin 4 or 5 on the tubes. One should be about 12v and the other should be zero.


----------



## digger945

Quote: 





testsubject said:


> Any tips on how to add some LEDs under the tube circuit wise?
> 
> Also:
> 
> ...


 


  You are not finished in this pic? It looks like nothing connected to pin 1(plate) and a wire going to pin 9(should not be a wire on pin 9)
   
  Up close pics would help.


----------



## nikongod

the tube sockets are wired backwards.


----------



## TestSubject

All right, here are some pictures of the sockets.
   
  EDIT: I read about 17Volts between pin 4 and 5


----------



## digger945

Nikongod is right. The sockets should be wired looking at the bottom of the tube. They are backwards.


----------



## TestSubject

All right! Thanks, is this a standard way of laying down pinouts?
   
  Soldering iron heating up.
   
  Hope this works.


----------



## digger945

Yep, wire according to the diagram you posted earlier, while looking at the bottom of the socket.


----------



## TestSubject

OK Well i am pleased to say that I can hear sound! We are getting somewhere. One channel is louder then the other and i can hear a buzzing sound in the background. I have tried to switch the 2 tubes but the same channel is louder. Could the Buzzing be cause by the PSU? What could make one channel not as loud? Looking back to my first Cmoy amp the same thing happen when a capacitor had been damaged. hope it is not the case here, none of them are swollen but still.


----------



## digger945

Check some voltages and compare the 2 channels.
   
  Power down and check the resistance from input RCA jacks to the grids, and to ground. Again, compare channels.


----------



## TestSubject

One Channel measure 19Volts between pin 4 and 5 while the other 27 Volts... Checking board now, probably a resistor right?


----------



## digger945

Your power supply is 48v?


----------



## TestSubject

Yes thats what is written on it however, when testing with voltmeter, I read 68Volts. Strange.


----------



## Fred_fred2004

That's ok it will drop under load


----------



## TestSubject

Thats what i thought but then remembered Volt meters have theoretical infinite resistance.
   
  EDIT: Same resistance between input and R14/R15


----------



## digger945

Measure between the grid and cathode for voltage.
   
  Measure voltage between the gate and source on the mosfets.


----------



## digger945

Allow the tube heaters time to warm before taking measurements.


----------



## TestSubject

0.42V between grid and cathode on the non working channel 1.7V on the working channel
   
  5.12Volts on both mosfets
   
  EDIT: It seems like one channel doesnt work at all, even after unplugging the non working channel , I hear no difference.
   
  REDIT: I am not the only one with a similar issue apparently. LINK Checked resistance between cathode and ground, Same on both tubes
   


> Left channel works gerat, right channel seems to only get some kind of cross talk - signal comes through but you have to crank it way up - the left channel is ear bleeding just to get audible sound out of right channel.


----------



## digger945

Check the resistance between the input RCA jacks and ground.
   
  68v is a bit high for your power supply. Is it 48v dc or ac?


----------



## TestSubject

Do you mean the resistance from the Ground of the RCA and circuit ground? If so, they are both equal.
   
  The Cisco PSU says 48Volts DC.


----------



## digger945

Measure resistance between RCA signal input jack(the center pin) and circuit ground.


----------



## nikongod

Draw 2 copies of the schematic by hand. Mark down what every resistance should be in your favorite color pen. Be sure to use ohm symbols. 
   
  If you can draw it from memory it is OK to use a computer printed copy, but I find drawing it by hand a few times helps me really "get into the circuit" so I'l pass that along. 
   
  With the amp off go through the amplifier and measure EVERY resistance you can. Measure from the furthest ends possible - IE if the resistor is on the board and connected to the tube with a long bit of wire measure from the ends of the wire. It doesn't matter that you used a 1Kohm resistor where a 1Kohm resistor belongs if you didn't solder one of the 3 joints its hooked up to.... Measuring one way only verifies resistor value, the other gives a pretty good assurance that you soldered it correctly too. Mark this down in PENCIL, making sure to use the ohm symbol. 
   
  It is OK for certain things to be slightly off from the values on the schematic, as long as both channels measure similarly. Depending how you measure, you may find stuff in the voltage divider to be off by a lot, but I doubt that's where your problems are. 
   
  After a bit of poking around with the resistance-meter you should have found something that makes absolutely no sense by now. Figure out why and fix it. Does the amp work? 
   
  If measuring resistances doesn't find anything (unlikely) turn the amp on. Measure voltages from EVERYWHERE to ground. Plate, cathode, gate, drain, source, etc. Mark this down on the schematics in pencil, making sure to note volts. Measuring voltages is often faster than measuring resistances, BUT it requires poking about in a live amp so Id save it for a last ditch effort.


----------



## TestSubject

OK, Sorry about the misunderstanding. Both at 102K Ohms


----------



## digger945

It would be easier if you did what Nikongod asks.
   
  Then post your findings.


----------



## TestSubject

No worries, already on it


----------



## nikongod

Quote: 





digger945 said:


> It would be easier if you did what Nikongod asks.


 

 When I am the ruler of the world you can be my head negotiator.


----------



## TestSubject

Quote: 





nikongod said:


> When I am the ruler of the world you can be my head negotiator.


 

 I can be sure of one thing, I wont be responsible of the technology advancements committee
   
  EDIT: on a more serious note, all resistors match both side of the circuit.


----------



## nikongod

That's a bummer. Measured from the furthest points? Tube socket and stuff. 
   
  Measure the plate resistors to the positive voltage rail (power off of course)
   
  Have you tried switching tubes from one side to the other? Its possible you have a bad tube. 
   
  After that, its all about checking voltages.


----------



## TestSubject

Have not checked the furthest point on all of them (did all the grounded resistors), but the sockets all check up. Will remake some test first thing tomorrow morning.
   
   


> Measure the plate resistors to the positive voltage rail (power off of course)


 
   
  I am sorry I am not sure I understand.
   
  I have switched the tubes and both seems to work.
   
  About Voltages, Digger945 suggested i sampled voltages between pin 4 and 5
   
   


> One Channel measure 19Volts between pin 4 and 5 while the other 27 Volts...


 
   
  Thanks much to both of you for helping me out! Of to bed now.


----------



## nikongod

Quote: 





testsubject said:


> I am sorry I am not sure I understand.


 
   
  Measure resistance from the positive voltage supply line (with the power off) to pins 1&6 on both tubes. 
   
  measure resistance from the gate (input) of the mosfet to the positive voltage line and ground. 
   
  Measure resistance to ground from pins 8&3 (should all be the same) and pins 7&2 (also all the same - 7&2 should vary as you spin the volume control)
   
  Measure as much as you can from the tube pins. This is key. Measuring just the resistors does not tell you if you skipped a solder-joint, or accidentally shorted something.


----------



## TestSubject

Okay after one more day of going through the circuit, i found a missing jumper, Ho boy I was happy, but one channel still doesnt work.
   

   


> pins 7&2 (also all the same - 7&2 should vary as you spin the volume control)


 
   
  The non working channel shows a significantly smaller resistance. Exemple, 2.7k while the other is around 12.2. However they both read 1k when pot is at one of its extreme
   
  EDIT: all measurement are done without the tubes plugged in.
   
  Thanks again


----------



## nikongod

Quote: 





testsubject said:


> The non working channel shows a significantly smaller resistance. Exemple, 2.7k while the other is around 12.2. However they both read 1k when pot is at one of its extreme


 

 Do the values change correctly as you spin the volume knob? 
  Measure them with the volume knob at every quarter or third of its rotation. for a 50Kohm pot it should be something like 1Kohm (volume all the way down) 2Kohm@1/3up, 10Kohm@2/3up, 50Kohm@max volume. Those are very rough numbers, from my head. Your results could be 50% different, but they should go something like that.
   
  If the dead channel goes up to 2.7Kohm and stops, where the live channel keeps going up past 12.2Kohm this is something I would investigate. It sounds like you accidentally shorted the grid of the tube to the cathode, but thats a wild guess. To confirm this guess measure the grid-to-cathode impedance with the volume knob at max volume. It should be ~50Kohm.


----------



## TestSubject

Okay, the non working channel does indeed stop increasing at 2.8K
   
  However the working one, at full volume, it displays 28K
   
  What on earth is going on...
   
  EDIT: i checked, they are in sync until 2.8K


----------



## nikongod

Do you have 50Kohm (or so) resistors across the input RCA's, not shown on the stripboard? that would explain why the good channel only goes to 28Kohm. 
   
  What does the resistance from grid to cathode look like with the volume knob all the way up?


----------



## TestSubject

> Do you have 50Kohm (or so) resistors across the input RCA's


 
  Yes I do, sorry for the un-complete design
   
  Between Pin 2 and 3, the working channel reads: 30K were the other reads: 1K
   
  EDIT: as always, measured with no tubes in


----------



## liamstrain

Same thing when you swap tubes?


----------



## TestSubject

I am afraid so.


----------



## nikongod

I'm totally sure you have a short somewhere. 
   
  My guess is that the 1kohm resistor between the grid(input) of the tube and the pot shorts to the strip that goes to the cathode on the side closer to the pot. It may also be where the pot wires to the board on that same strip. Flip the board and check there.


----------



## TestSubject

I am very sorry sir but I need to go now, the amp sound so sweet to BOTH of my hears I really have no time to say thank you.
   
   


Spoiler: Warning%3A%20Spoiler!



After taking the Amp apart 4 times, and resoldering many times, I may have shorted the input to the cathode.


----------



## nikongod

Cool! Glad its working.


----------



## TestSubject

Everything is in place, will be taking shots soon.
   
  I have one Mosfet heating more then the other. I really hope the heatsinks are big enough, I mean they are hot! The datasheet say 175 Degrees but...
   
  EDIT: After putting a droplet of water on the Mosfets, the water evaporate, they are running over 100 degrees...
   
  REDIT: Note that both tubes are not the same model, might explain the difference?
   
  Also buzzing and clic-ing in the background at about 2/3 of the Volume.


----------



## digger945

is your power supply rated for 110vac input or 220vac?


----------



## Fred_fred2004

If he's using the normal 48volt supply, its a switcher rated 100-240volt
   
  cheers
  FRED


----------



## TestSubject

Yes, the Cisco PSU I am using is rated 120-240AC


----------



## TestSubject

Ho my what do we have here?
   

   

   

   
   


Spoiler: Warning%20Ugly!



Form VERY hot to warm:


----------



## digger945

^Looking good there Pierre.
   
  The volume knob turned out looking pretty nice, I think.
   
  Did you get the high power supply voltage down, or is it still running about 68v or so?
   
  I would like to see about 12v to 13v across the heaters. I'm not sure how they will last with almost double the rated voltage on them.


----------



## nikongod

Quote: 





digger945 said:


> I would like to see about 12v to 13v across the heaters. I'm not sure how they will last with almost double the rated voltage on them.


 

 This.


----------



## TestSubject

I get about 16V at the source of the Mosfets. Also, why are they so hot? Aren't my heatsinks big enough?


----------



## nikongod

16V is too much. 
   
  Why so hot....
  What is your B+ voltage? it should be 48V, so lets go with that. 
  you said you have 16V at the source of the mosfet, so OK. 
  I Will ASSUME that you only have 150mA=0.15A going through the tube. This is the rated current at 12V, so it is probably more at 16V.
  P=V*I
  (48V-16V)*0.15A=4.8W
  heatsinks that size will get hot burning off ~5W. 
   
  If you still have 60V or whatever it was for B+ you have even more power being burnt off in the mosfets. 
  If you have more than 150mA going through the mosfets (and you almost definitely do) you have even more power burning off in the mosfets...
   
  At this point you have options. 
  Tweak the voltage divider resistors so that they get you the correct voltage at the source of the mosfet. 
  Add a series resistor between the tube heater and ground to take up some of the voltage. A 27ohm, 2W resistor should do it. 
  There is a backdoor option #3, but I'm not totally sure it will work. I think I will call it the "hungry hungry hippo".
   
  Ignoring the mysterious third option, I'd personally add the resistors on the heater supply. I would reccomend that the resistor be on the ground side rather than the mosfet side, and yes there is a difference. Having the heater at a higher voltage than the cathode reduces the odds of some funky "diode effect" where AC on the heater leaks back into the cathode. Its probably just me being anal retentive here, but it doesnt cost anything more to maybe be better or at worst the same... I'l post a schematic in a sec. 
   
  I think I need to build the Hungry Hungry Hippo now. How could it be bad with a name that awesome?


----------



## nikongod

Use at your own risk, Im pretty sure its good though.


----------



## TestSubject

I have really limited acces to parts, 27ohms 2W, I wont be able to get them soon...
   
  Why on earth is my Power supply rated 48 volts and outputting way more like this? I mean it is for Cisco equipement, you would think it is quality? Or maybe it as nothing to do with the PSU?


----------



## Fred_fred2004

Whats the model number of your Cisco power supply? do you have the correct one?
   
  Mine is rated 100-240volts output 48volts, unloaded its putting out 49.5V
   
  cheers
  FRED


----------



## TestSubject

My cisco PSU  is model PSA18U-480C Output: 48V AT 0.38A
   
  It as the Cisco Logo but I did got it off eBay


----------



## digger945

Disconnect the power supply from the amp and measure the voltage at the power supply plug.


----------



## TestSubject

I had noticed this before but i though i was turning crazy... When you plug the power supply, it start at 50 something Volts and keep increasing. After a minute or two its at 62Volts and still going up.
   
  Tried Input at 220 and 120 using a transformer.


----------



## digger945

Hook up your voltmeter to the power and measure the voltage with the power supply connected to the amp, then slowly and carefully move your hand close to the mosfets and observe the voltage. DO NOT TOUCH ANY EXPOSED WIRES!!!


----------



## nikongod

Dont do the resistor thing I posted above until after you sort out the power supply. I didnt think about the voltage reference being based on a funky B+


----------



## mosshorn

I wish I knew more so I could help on this ordeal, this really seems like a great project, especially since I don't exactly know how I would go about doing it point to point :X


----------



## TestSubject

Feel free to use the design and ask for help if you need.
   
  New power supply is on it's way, should fix my problem.


----------



## TestSubject

Happy to say that the amplifier works well now, I may want bigger heatsinks but everything else is fine.
   
  Thanks everyone and hope this project will get more people to build this amazing amplifier.


----------



## mikkelmmk93

Hi Guys.
  What is the sonics of this amp? Dark, bassy, treble emphasiz?
  And do you know what price of amp it stacks up against if you were to buy one?


----------



## tomb

Quote: 





mikkelmmk93 said:


> Hi Guys.
> What is the sonics of this amp? Dark, bassy, treble emphasiz?
> And do you know what price of amp it stacks up against if you were to buy one?


 
http://www.head-fi.org/t/319231/millett-starving-student-hybrid-amp


----------



## Frodo

Quote: 





testsubject said:


> *EDIT: This is old. Please, go have a look at the lastest post as the Stripboard design as greatly improved and i hope will be operational soon. Here is Rev 3.7: LINK*
> 
> *Components are ordered, Will start building soon.*
> 
> ...


 

 Fantastic effort, thanks so much for sharing (also of course thanks to everyone who helped you), I'm starting my build using exactly your stripboard design. It might be a bit of an obvious question to most people, but where did you connect your LEDs; also I know it was quite a while ago but are you able to post any photos of the top of the board showing the components in place. many thanks


----------



## KimLaroux

Most people connect the LED across the tube heaters. Since it's around 14v, you don't need a large resistor as would be necessary if connected directly to the power rail. Plus the power already is at the socket, so you don't need extra wires.


----------



## Frodo

Many thanks , I soldered everything onto the board today and the case is already done, so hopefully I can start testing it out in a day or two. 
   
  I noticed that R6 is missing from the stripboard design, was there a specific reason for this? I've been though the whole thread but couldn't find anything.


----------



## Goobley

R6 is there, just above R12, it's just been mislabelled as R8. I'm personally using a large resistor for the LED as I feel that it must affect the bias across the tubes, I don't have any evidence to support this though, and Kim knows more on this subject than I do. I don't think you can go wrong with either method.


----------



## Frodo

Thanks I'm glad you told me about R6, I had a the R8 390k resistor there,  so actually R8 & R10 are missing from the diagram,  am I right in thinking that the jumpers either side of C4 are wrong and should actualy be R7 & R8 and the and in place of R7 in the  current diagram in should be R10?


----------



## Goobley

Yes you're right, however all the resistors are actually on the diagram, but it's not just R6 that's mislabelled. 
   
  The two resistors on either side of C4 are actually just vertically positioned and are indeed R7 and R8 and yes the one labelled R7 is R10.
   
  A good rule of thumb is that any amp like this should be more or less symmetrical (here the only bits that aren't quite symmetrical are the two decoupling capacitors as the amp is single rail)
   
  Good luck with your build,
  Chris


----------



## KimLaroux

Hmm yeah now that you're saying, there are some errors in the drawings. R7 ans R8 are there, positioned vertically, but unidentified.
   
  Here, I fixed it and clarified a few things.

 Corrected the resistors to match Millett's schematic.
 Added signs for the capacitors' polarity, at the point where they go trough the board.
 Clarified what the white square with red dot means.
 Added some squares where you should cut the strips. The strips carrying signal should be cut as short as possible. 
 Moved the plate's wire up a strip and added information. The cyan dot, did it really have a reason to be on the strip it was? This wire carries signal and is sensitive to noise. I moved it up a strip, removed the jumper and shortened the strip.
 Added the MOSFET TO-220 pinout, picture taken from the datasheet.
 Changed pin 4's color, to distinguish it from the right channel's signal input.
 Corrected the labels of the outputs.
   
  @TestSubject, I know I should probably ask before modifying your drawing, so if you have anything against it just tell and I'll remove the image.
   
   

   
   
  These aren't errors per se, just recommendations: 

 R16/R17 should be soldered directly to the pot's pin to lower noise. 
 Ideally, R14/R15 should be connected directly to the tube socket, and the signal wire from the pot should go directly to this resistor, to lower noise. It's a bit silly to make the signal go trough the board just for a single resistor, especially since this signal is the most sensitive to noise in the whole circuit. This is less a problem if you already twist the wires together, though. In this case you should use two grround wires to the pot, and twist one with each signal wire.
 C7/C8 is confusing on the drawing. Make sure it's connected on the same strips as R5/R11, and not the ones over and bellow it. Take the polarized caps as example: the + and - are where the leads go trough the board.


----------



## Frodo

Thanks, everything is wired in to place now. But it looks like by following the original design I have the wrong polarity on C3 and C6.


----------



## Goobley

I'm struggling to tell from that picture (it's never easy to take clear ones of this sort of thing). But I would guess that yes they are of incorrect polarity.
   
  I'm also slightly worried about the length of your wires inside the box - my advice on that would be to try it and see whether it works, if it you get noise then you know where you should start looking. Anyway, I'd just sort out the issues that are known to be issues, try it and worry about the unknowns later. Good luck with it.
   
  Nice work again Kim, you're always extremely helpful on this sort of thread.


----------



## Frodo

Thanks to everyone for their help today, I managed to get the amp up and running about an hour ago, after a few false starts. It's nice and quiet, in fact with nothing playing I can turn it up to about 80% before I even get a slight hiss. It sounds very nice as many people have said, but I do have one concern, it gets hot, after about 20 minutes the heatsinks are very hot (you can touch them but you can't keep your fingers there for long) the tubes also get warmer than I would expect. Is this normal?


----------



## Goobley

Totally normal, it's a very hot amp due to its unique use of the gets, I wouldn't worry about the heat. Tube filaments are also of course like lightbulbs and get similarly hot. That's a very nice looking amp you've built and your a lucky bugger for having it nice and quiet . I have been and still am having problems quieting mine, are you using the stock power supply?
   
  What cans have you plugged into it?
   
  I have to say that that retro look you've got looks really nice with those JJ tubes as well.
   
  Cheers,
  Chris


----------



## KimLaroux

Nice job! It looks cute, if such a word can be used to describe an amplifier. 
	

	
	
		
		

		
			




   
  So you changed C6 and C3 around before turning it on? They were indeed reversed in the picture you posted.
   
  I am too very surprised your amplifier is so quiet, especially considering the messy wiring... I think it's simply your headphones, which do you use with this amp? Are all of your headphones as quiet?
   
  I've spent hundreds of hours and dollars on my build to make it quiet, and it's still too noisy to be used with my Shure SRH-440. It's usable with my Q701 though. For some reason the AKG headphone is quieter.
   
  You could easily cut 1/3 to 1/2 the length of all the wires. I see you twisted each input signal wire around a ground wire, this is great. The next step would be to clean up the tube's wiring, as those too carry sensitive signal. I'm just not sure how you should do it... maybe someone with more experience can tell.
   
  The MSSH do get very hot. MOSFET needs to be biases with a relatively large current in order to be usable as audio amplifiers. Your heat sinks should be just good enough, as they seem to be what most people use. To verify if your amplifier is not getting hotter than it should, simply measure the heater voltage once everything is warmed up. It should be around 14v. Anything higher than this may be too much. Check both heaters and report back, we'll see then if tweaks are necessary.


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## Goobley

My reasoning as to why the akg is quieter than your shure is purely due to the large amounts of power it takes to drive. Looking at innerfidelity's datasheets:
   
  http://www.innerfidelity.com/images/ShureSRH440.pdf
  http://www.innerfidelity.com/images/AKGQuincyJonesQ701.pdf
   
  we can see that the shure requires 50mV and 0.06mW to reach 90dB
  the AKG on the other hand requires a whopping 318mV and 1.68mW of power to reach the same output levels.
   
  Obviously you have to turn the amp up louder to use the akgs at the same SPL, however I know that in my build (and I'm taking the liberty of assuming that yours is the same) the noise stays more or less the same until I get into the last 1/4 of the pot's turn, therefore it would be orders of magnitude less noticeable in your akg.
   
  I'm still looking at mine but it seems pretty safe to say that the SRH440s and the SSMH don't seem to get on.


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## KimLaroux

Hey thanks for the information! I never noticed those measurements, but they do explain what I observed. The 440 indeed need very little power. I actually had to modify the low gain setting of my NFB-12 to be even lower, because it was too loud with my 440.
   
  In my build, the noise does get higher as I turn the volume up. In fact, it's almost silent when the pot is at minimum volume. The SNR stays more or less the same at every volume level. My 440 are dead silent out of my NFB-12 so it's possible for an amplifier to be silent even with these. I'm just clueless if it's possible for a tube amplifier to be as silent, though. In the meantime, I'll keep on making researches an tweak my MSSH until the SNR is lowered to an acceptable level.


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## Frodo

Thanks for the encouraging words. Still a few things to do, such as Kim mentioned,shortening wires, and moving R16/17 and R14/15 closer to the pot and tube socket. It was just luck that I had used 2 ground wires and twisted them around the signal wires, I didn't expect any advantage over such short distances, (and yep also had to change C3 & C6 to the opposite polarity)
   
  I noticed that the pot also has the occasional crackle when I move it, probably because it was cheap, I'm not sure how it will effect overall sound, or if there will be any major gains by using a more expensive audio pot.
   
  The headphones I was using to test the amp yesterday were just an old pair of cheap JVCs. I've now tested it with my HD595 and ATH-M50s, it's still very quiet, although now I can detect a sight hiss at the very edge of my hearing (slightly more noise just after power on, but this drops away quickly, interestingly there is more noise with the case open), I wasn't sure if I was imagining it at first. I know mine are a long way from audiophile cans and are easy to drive without amp. I'm hoping to get some HD650's soon, so will give my thoughts later using something with a bit more impedance. At the moment  1/4 to 1/3 volume is a comfortable listen level for me (using an iPod classic as the source).
   
  I'm very pleased with the sound so far, I don't have great deal to base it on, but it's definitely sounds better than the Cmoy and Cmoy Tube hybrid amps I previously built (not to take anything away from Fred_fred2004's kits, which are excellent), but the SSMH seems to have better resolution, I'm hearing new things in recordings that I had never noticed before. Looking forward to making an Objective 2 amp at some point in the future.
   
  The case is just cheap metal one from an electronics shop, I have the same type I used for my alien DAC, I bought them to match, but I read afterwards that the SSMH might destroy the Alien so I haven't tried them together yet. I'm building a Skeleton Dac next which is a little cheaper so I might try the SSMH with that.
  
  The power supply I am using is 48v 0.52A (rated 100-240v) made by FSP, Model # 025-1AD207A http://www.fspgroupusa.com/fsp0251ad207a/p/445.html It was $8 on ebay. (tested with a digital volt meter the voltage switches between 47.7 & 47.8 continusly (anyone know why?). The amperage is a little higher than the CISCO, I thought this might be good if I wanted to use LEDs. At the moment though I'm happy with the glow from the fillaments.
   
  When I switch it off, the volume drops away to nothing and then comes back again for a second before dropping away completly (the power Led also follows this pattern), is this just the caps discharging?
   
  The voltage at the heaters (measured between pins 4&5) is: 12.5 volts for both tubes.
   
  The heat on the heat sinks still worries me,
   
  I'm using standard 34x42x25,4mm heat sinks, I'm going to change to these http://www.aavid.com/products/standard/530002b02500g which are 30mm taller, hopefully it will improve things.
   
  All the best, Andy


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## KimLaroux

12.5 V is as low as you can safely go, so your build is not wasting more power than it should. As for the heat sink I had to use a fanless slot CPU heat-sink to keep everything cool. I used to have a smaller heat-sink, but it was getting too hot. I burned my fingers a few times just by touching the heat sink, which is usually not a good sign.
   
  Before:

   
  After:

   
  Now everything gets equality hot. The MOSFET, the linear regulator and the transformer all get very warm. I rarely use the amp more than an hour or so at a time, just to be safe. Note that the MOSFET are probably the toughest of the bunch. They can safely operate up to 175 C. A normal MSSH dissipates around 15W as heat, which is quite significant for an headphone amplifier. I think the higher heat sinks would be good enough though. If I compared the data correctly, they should stay cool enough (around 50 C).
   
  I think one of the reasons why your build is so silent is that you used a ferrous enclosure. As you noticed, the amp got more noisy when you opened the case, which tells me the steel case really helps. But then some people built them in plastic enclosure and report they are silent...
   
  It's normal that you have ~47.7 V from your power supply. The product datasheet says the regulation is within 5% of 48 V, so 47.7 is actually quite good. It's nothing to worry about. Your DMM "jumps" between 47.7 and 47.8 is also nothing to worry about. It's probably the voltage oscillating by a fraction of a volt, which happens to go up and down the threshold your DMM has to round to 0.1 V. I'd worry if it oscillated over 0.5 V.
   
  And yes, the amp slowly turns off as the capacitors discharge. It's recommended to unplug your headphone before turning it off though, as the discharge can place DC on the drivers which can damage them.


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## Frodo

That is is one very cool looking amp! I remember reading on the original SSMH thread about about the problems you had with your clear case and heat, which is one of the reasons why I stayed away from plastic and wood. I listened to mine for about 1 1/2 hours last night and heat sinks got hot, but not hot enough to burn, but I will still be happier with the taller ones I think. I also noticed that I can no longer hear the slight hiss that was at the edge of my hearing, it's noise free apart from the crackling pot up until 80%, perhaps there is some sort of settling in time? I don't know if there is a techincal word for it.
   
  I want to build another now  it's a shame the 19J6 tubes are so expensive these days, I know the original amp ran at much cooler temperatures. The stripboard method definitely puts a nice sounding amp in the hands of beginners, thanks for sorting out the final layout Kim, if you hadn't I might have ended up shelving the whole thing.
   
  Couldn't resist adding the LEDs across the heaters, I know they are frowned upon, but I'm a noob so I'm still at that stage where LEDs still look cool to me in everything 
   
   

   
   
  For anyone who is interested, the case size of my case is 120x78x50mm, it was a tight fit to get everything in so I wouldn't recommend using anything much smaller with the stripboard design and vertically soldered  components. Saying that, the switch I used is pretty big so you could save a fair amount of space if you used something different, and used maybe just a 1/4" jack and 3.5mm for the input, I also have RCA connectors and maybe having both is a bit of overkill.


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## TestSubject

First off well done Frodo and excuse my messy diagrams... It was some time ago and I had little experience. Not that I am an expert now but anyways.
   
  As for the forever helpful comunity thank you. I have put my head-fi notification off and I was not there when Frodo needed help.
   
  @KimLaroux Thanks for the fix. Would you mind if I put your diagram on the front page? Is so I will remove it.
   
  Also I was a bit worried of the heat the amp produced specially since I had pretty small heatsink, after using an infrared thermometer, it is safely within the range of the TO-220s. Just watch your fingers haha.
   
  EDIT: OP has been updated.


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## Grumus

Great thread and lovely builds! 
	

	
	
		
		

		
		
	


	


 I have been doing some research towards doing my own amp and have settled on SSMH (I think). Before I order parts and get the iron hot I have a few questions. 
Source: Laptop
  Phones: Sennheiser HD598 (50 Ohm)
   
   
1. Is there any advantages to using a ground plate and point to point wire it over a strip board? As I see it strip board is a sure way to reduce the length of wire used. Of course I will wire the rest as tidy as I can to my ability to reduce noise.
  2. I mostly sit at the computer when I use my headphones, which includes gaming, movies and music=long hours. Can I use this amp for long sessions at the time since it gets hotter than 19J6 builds?
3. What should I be looking for in heat sinks. What values do you recommend since I want to use it for long sessions at a time? 
4. Would it be feasible to hide the heat sinks inside the build with openings to let air in and out? (mainly for aesthetics)
5. I have heard turning the amp on or off could release DC voltages straight to the phones damaging them. Is this true? If so is there a way to build in protection for this? I want the amp to sit pretty on my desk and just be turned on and off by anyone without problems.
   
  Appreciate any answers! Oh any particular advice to a first time builder? Looking forward to the build so much I am dreaming about it


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## Frodo

Hey Grumus, I'm not as qualified as the others to answer your questions but I'll give it a try.
   
  1. I think the only advantage using a stripboard has over point to point is that it's easier to build it that way for those of us who are not used to following circuit diagrams or who are not confident in point to point soldering. You might find that you actually end up using more wire with the stripboard design than point to point (I'm sure I did).
  2. I use my amp just to listen to 1 or 2 albums at a time, it does get hot, it probably won't be a problem for longer listens, but I really only use it for special occasions when I can really sit down and enjoy it. It has a very unique and enjoyable sound. Other might disagree, but think you are better off with a small solid state amp for gaming and movies. My SSMH also takes a couple of minutes to warm up, it still crackles a little at first.
  3. I changed my heatsink for larger ones, the ones I have now are 20mm taller than the ones in the photo. They still get hot but they wont burn you, my guess the temperature stabilizes at about 55oc, which I think is about what KimLaroux calculated . I'm sure you could use bigger heatsinks, but there is probably some law of diminishing returns. I'm sure someone with a physics background could tell us about that.
  4. Personally I wouldn't put them inside the case, they need to dissipate a lot of heat. Perhaps if your casing was some sort of mesh cage or you had fans it might be ok. To me though I think it would over complicate things.
  5. Yep, you can get a bad spike, always remove them before turning the power on or off. I think you can buy/build a suppression circuit, but it just complicates things. Maybe think about mods later. If you need an amp for everyone to use possibly a valve amp is probably not the best choice, have you looked at kit amps like the O2. I have one and it's a great little everyday desktop amp.
   
  My advice, just take your time with the starving student, plan the layout well and use very cheap headphones for the first tests. It's a very satisfying amp to build, I still love the sound of mine. In fact I think I'd like to build another.
   
  Oh, and don't go too small with the case if you decide on using the stripboard.
   
  Hope to see some photos of your build soon!


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## Grumus

Thanks for the answer! 
   
  1. Alright, I am confident with soldering and confident enough to follow diagrams. So I might go for point to point anyway. I will order it with stripboard anyway.
  2. Ok, I will get quality heat sinks for it anyway. And if it's only adequate for shorter periods I will have a good reason to build a solid state 
  3. Big(ish) quality sinks check!
  4. Ok, will think hard before I place them in a bad spot.
  5. Might use it as my personal amp then if I cant find a reasonable way of adding protection. I have looked at the O2 and it's abit pricey since I am actually a starving student!
   
  If I go for point to point I am thinking of having a big ground plate and mounting everything on that (like the bottlehead crack). Is it a bad idea to have the common ground open like this safety wise? I know it's not a deadly amp but I want to do it right so I wont make mistakes in the future.
   
  Yeah I am thinking of doing a CAD model of the entire amp before I build it to get a better feel of the project (and a bit of CAD fun!) Will post pics if I decide to CAD it for others to get a feel for the layout.
   
  Thanks again!


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## DingoSmuggler

Quote: 





grumus said:


> Great thread and lovely builds!
> 
> 
> 
> ...


 
  You aren't going to get very good results amping the output from a laptop. Laptops are typically the worst quality sources available. You will want to get a USB DAC to make the amp building exercise worthwhile. Sorry to say it to a bonafide starving student.
   
  2 - the overall heat is the same between the 2 builds, both have 150mA through the output stage at 48V. The difference is how the power is split between mosfet and tube heater (power = heat). The 19J6 has 19V across its heater leaving 29V dropped by the mosfet, and its 12.6V and 35.4V with the 12AU7, so the mosfet is dissipating about 1W more heat (6.4V difference x 0.15A).
  The extra power dissipated in the mosfets is still well within their limits, the IRF510 happily run hot compared to other devices, so it just comes down to how hot you want your heatsinks.
  In terms of listening time, heatsink temps stabilise at a set temperature above ambient, there is no limit to how long you can safely run the amp, unless its not getting fresh air (shut in a drawer or cupboard etc)
   
  4. if putting inside the case, then the case has to be able to easily dissipate the 11W that the 2 heatsinks are releasing into the case, otherwise everything else inside is going to get hot too. You would need heaps of airflow for this to be feasible.
  Another option would be to use other heatsinks you prefer the look of, the possibilities are endless.
   
  5. easy enough to use a protection circuit. amb's epsillon 12  is one such item. You could also copy the relay output protection from the minimax schematic which i believe is a simplified version of the same circuit.
   
  If you really need to keep costs down then have the headphone output going through a switch to setup a manual delay.
   - turn on the power switch
   - wait 30 seconds
   - turn on the headphone output.
  and turn off in the other order (but no need to wait 30 seconds to turn off)


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## Grumus

Maybe I should build a DAC as well and put it in the case? Do you have any good tips of DACs that will work well with the starving student? I have heard that it can destroy DACs.
   
  2. I actually got my hand on 19J6 tubes for 6 dollars each at a radio museum right next to my school. Had no idea I had a source for tubes that close to me until yesterday! Good to hear that the listening times can be long! And I will get a big heat sink to keep me if not the mosfets happy.
   
  4. Maybe I will just put them on the back behind the amp.
   
  5. I have been searching around and this is what I need (I think). 
   

  It's the e12 delay circuit from the Millet Max. This would seem like a good way of protecting my phones. I would need some help in how to connect this in the amp and what values each component should have. Would be great if someone could put this together with the amp scheme. 
   
  Maybe I just should go with a switch system but I would be very proud of my self if I made it user friendly for everyone


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## KimLaroux

Quote: 





grumus said:


> [...]
> 
> 2. I actually got my hand on 19J6 tubes for 6 dollars each at a radio museum right next to my school. Had no idea I had a source for tubes that close to me until yesterday! Good to hear that the listening times can be long! And I will get a big heat sink to keep me if not the mosfets happy.
> 
> [...]


 
   
  Do you know how many they have in stock? For the price they let them go, I'd guess they have a significant amount... And if that's the case, I know someone who'll buy the lot. Just don't go and tell them they are actually rare and wanted tube, cause they may jack the price up.


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## Grumus

Unfortunately they only had like 5-6 tubes and only 2 of the same brand. The radio museum is driven by a few pensioners who have worked with or designed radios in the past. I told them it was rare and how lucky I was to find them, I highly doubt they would jack the price . But next time I swing by I will ask them if they would know of a place to get some more. My guess is they will  probably know if there is any place to find more in Sweden.


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## audi0lurker

So very ammatureish question, But I am indeed an amature.  
   
  So I will be using a proto board like the one above however there are no strips.   The boards I have are literally just a bunch of independent holes I can solder to.  SO I guess this means I will have to run a wire from each component to the ground individualy correct?  I wish there was a way to connect a whole strip on my protoboard as ground.
   
  And even more basicly,  How do I ground this?  This is my first expererance ever needing to ground something.  Do I simply attach it to the case or what.
   
  Thank you for the help. this thread has been great so far.


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## scootsit

Quote: 





audi0lurker said:


> So very ammatureish question, But I am indeed an amature.
> 
> So I will be using a proto board like the one above however there are no strips.   The boards I have are literally just a bunch of independent holes I can solder to.  SO I guess this means I will have to run a wire from each component to the ground individualy correct?  I wish there was a way to connect a whole strip on my protoboard as ground.
> 
> ...


 

 Don't use that protoboard, it is a huge pain. You definitely want stripboard. If you flip through my pictures, I built a regular old millett on stripboard. I can send you the board layouts.


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## ricardobayes

Hello there,
  After studying the stripboard layout, it is quite unclear to me where the Q1/Q2 Mosfets go.
  Are they connected to the R2, and R8 resistors in series?


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## KimLaroux

In the middle of the right half of the board picture, there are two rows of 3 black dots. This is where the mosfets go. If you look lower, bellow the board, there is the pinout of the 3 dots rows along with the pintout of the mosfet.
   
  Actually, the mosfets are supposed to be mounted on heat sinks. You then wire them to the board.


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## ricardobayes

Okay, thanks a lot  Now I finished soldering, waiting for PSU to arrive. By the way, I saw that the Cisco 48V one is more or less precise to 0.1 Volts. Is that punctual enough for hi-fi use?


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## KimLaroux

Quote: 





ricardobayes said:


> Okay, thanks a lot  Now I finished soldering, waiting for PSU to arrive. By the way, I saw that the Cisco 48V one is more or less precise to 0.1 Volts. Is that punctual enough for hi-fi use?


 
   
  The output voltage isn't really relevant to it being hi-fi or not. The important thing is it needs to be a clean and stiff voltage. I think the recommended PSU proved its worth by now.


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## ricardobayes

Hello everyone. Managed to assemble everything, but hearing no sound from the amp.
  I'm measuring 13V between pins 4 5 on one tube, nothing on the other. However, the 0V tube doesn't heat up.
  Another measurement between the MOSFET gate and source: 3,43V on the good side, 48V (!) on the other one.
  Any suggestions?


----------



## Goobley

Sounds like a blown MOSFET, Vgs should always be around 4V for standard fets. Then again the gate should be at about 17-18V not 48V so recheck the warning on that side, in particular the voltage divider that biases the MOSFET and if you have a spare there's no harm in replacing the MOSFET.


----------



## ricardobayes

Question. Should pin 1 and 6, 2 and 7, etc. be connected at both tubes?
  I wired the thing as pin 1,2,3,4,5 to one tube and 4,5,6,7,8 to the other.


----------



## KimLaroux

Quote: 





ricardobayes said:


> Question. Should pin 1 and 6, 2 and 7, etc. be connected at both tubes?
> I wired the thing as pin 1,2,3,4,5 to one tube and 4,5,6,7,8 to the other.


 
   
  the 12au7 is a twin-triode. This mean it's got two triode in each tubes. In the MSSH, each triode is connected in parallel. To parallel them, we connect pin 1 and 6 together, 2 and 7 together... etc. 
   
  Note that the amp will still work if you only use one triode, but it won't be working at the operating point that it was designed for.
   
  The way you connected it is using half of both tubes for a single channel... so what did you do with the other channel?


----------



## ricardobayes

Just left them floating 
  Now I'm rewiring the tubes


----------



## ricardobayes

Hi, it's me again. Managed to rewire the tubes and now there is sound on both channels.
  However, it is not amplified and it is quite distorted and the lower frequencies are missing completely.
  Any pointers on where to start debugging?
  I have a 10k pot as the volume knob. Measured resistance on pin 2 of tubes, they both go up till 10k if I turn the knob.
  Also should the tab of the FET be connected to Drain?


----------



## KimLaroux

Quote: 





ricardobayes said:


> Hi, it's me again. Managed to rewire the tubes and now there is sound on both channels.
> However, it is not amplified and it is quite distorted and the lower frequencies are missing completely.
> Any pointers on where to start debugging?
> I have a 10k pot as the volume knob. Measured resistance on pin 2 of tubes, they both go up till 10k if I turn the knob.
> *Also should the tab of the FET be connected to Drain?*


 
   
  No, the tab is already connected to drain, internally. This is why we need to electrically insulate the tab from the heat sinks.


----------

