# Starving Student PCB's



## Fred_fred2004

I needed some Starving Student pcbs and the only way to get a decent price was to buy quite a few, I have checked with the moderators and it's ok for me to sell these at cost plus postage There always seems to be someone wanting to try their hand at building the SS this is the 12AU7 version
  
 This is what they look like
  

  
 This simply is the assembly low to high
  



 Tube sockets go on the other side

  
 final bits
  

  
 Dont forget the heatsinks
  

  
 Ready to find a case and you're good to go
  

  
 These are the values of the part I used
  

  
 MY MISTAKE C2 & C4 are marked on the board as C11 & C10 - WHOOPS 
  
  
 This board is a layout I made some time ago its super reliable very stable and works first time just plug in the right parts, the boards are $3.75 + $3.00 postage worldwide
 If you want more than one board the postage will be at cost only
  
 Give a yell if you want a board


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## Avro_Arrow

Great job Fred_Fred!
  You're such a credit to the community.
  I'm sure they will go quickly.


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## Fred_fred2004

Thanks Avro thats very nice of you to say so 
	

	
	
		
		

		
			




   
  Yes I'm posting the first few this morning, so I hope we'll see some being built and enjoyed
   
  cheers
  FRED


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## Zashoomin

I think this is something a lot of people have been waiting for including myself.  God I want one but I don't want to do the casework.  You put me in a rough spot haha


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## Fred_fred2004

Posted several now and I've got the postage sorted 
   
  2 boards $3.00 world wide
  more than 2 boards postage jumps to $6.60 but that can be up to 250g so several boards in one package
   
  cheers


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## Martinus

Hi Fred

 I recently built a stripboard version of the 12 AU7 amp and whilst I'm pretty happy with it I think the next one deserves a PCB. 

 Could I order two boards please?


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## Fred_fred2004

Yes no problems justy pm your email address and I'll send a PP invoice
   
  cheers
  FRED


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## dsavitsk

fred_fred2004 said:


> There always seems to be someone wanting to try their hand at building the SS this is the 12AU7 version




Indeed! Great to see someone picking up on this project. Looks like a nice board.


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## Fred_fred2004

@ Dsavitsk
  It's thanks to your work in adapting the SS to 12AU7's that we can all enjoy a very cheap fun project 




   
  cheers
  FRED


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## onyu

Can I have 2? 
  Always fun to build some stuff.


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## Fred_fred2004

@onyu
  Sure just flick me your email address and I'll send an invoice
   
  cheers
  FRED


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## spazmochad

I'd like to buy two please, should be interesting to see if the p2p version I built is as good


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## Trower

I would love to buy 3 if I could!


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## jasonf

How many do you have left roughly? I am looking to get into DIY but wanted to do some more reading first. Hmm one or two....


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## Fred_fred2004

There is no problem with numbers at the moment so I can supply 1 or 2 easily
   
  cheers


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## KimLaroux

Great job. I like how compact the board is, yet leaves enough space between the components for upgrades.


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## Fred_fred2004

Quote: 





kimlaroux said:


> Great job. I like how compact the board is, yet leaves enough space between the components for upgrades.


 
  Thanks its been very reliable and stable, I just got over using toner transfer to make it 
   
  I used it to make this a while ago
   


   

   
  Still gets an airing every now and then
   
   
  cheers
  FRED


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## ahoken

Hi Fred, 
   
  Do you have any more starving student pcb available? I am really interested in buying you a couple of them. 
   
  I will wait for you. 
   
  Thanks a lot
   
  Mike


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## HolyCheese

Would it be hard to convert this board from the 12AU7 to 6922 type or the PCC 189 or anything equivalent. 
  Should I look at the values? I think the 12AU7 is a bit similar but with different values if i'm not mistaken.


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## Fred_fred2004

@ ahoken 
 No problems just send me your email and how many
 cheers


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## Fred_fred2004

Quote: 





holycheese said:


> Would it be hard to convert this board from the 12AU7 to 6922 type or the PCC 189 or anything equivalent.
> Should I look at the values? I think the 12AU7 is a bit similar but with different values if i'm not mistaken.


 
  On a 12AU7 pins  4 and 5 are the the 12.6 volt heater with pin 9 as the centre tape for 6.3v operation

 On a 6922 pins 4 and 5 are the 6.3v heaters with pin 9 as the shield
   
  so it would need some mucking about 
   
  cheers


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## ahoken

I found that product to replace c10 and c11 caps do you think it will fit for the use? 
   
http://www.digikey.ca/product-detail/en/B32652A6224J/495-1335-ND/592911
   
   
  Thx


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## Fred_fred2004

I'm guessing you mean C2 and C4 and yes it would work but the lead spaving is 15mm so you'd need to do some lead bending to make it fit
   
  cheers
  FRED


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## Martinus

PCBs arrived today. Lovely etching quality and such a tidy wee board. 

 Looking forward to building and testing. Thanks very much, Fred.


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## Fred_fred2004

Still got a few left


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## jasonf

Quote: 





fred_fred2004 said:


> Still got a few left


 
  I might get a couple more once I receive my order and check out how they are. Hopefully they come soon.


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## Trower

Finally had the time to open mine, and man they are really well laid out and very well made! Nice job!!


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## Frodo

Hi, The boards arrived today.
  They look fantastic,
   
  Many thanks!


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## Eerie

Fred, are you still selling them?


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## Fred_fred2004

yes mate, just drop me your email address


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## onyu

Fred, got them a couple weeks ago but forgot to say here  they look very nice. Thanks


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## mawoca

Mine just arrived in the mail today. Needless to say I'm very excited to place an order at Mouser and hunt for some cheap tubes on eBay  Thanks again, Howard!


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## jarscrew

My package just arrived today, thanks Howard for fast shipping. Soon me and my friends will buid it..


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## Frodo

I put my amp together today, everything was looking great , I'd even found a working power supply in a junk bin for $2 and some nice 1960's tubes ..... final job mounting the Mosfets to the heatsinks .... Doh! I realised that I don't have any of the ceramic mounting kits. Does anyone know where I can buy them or have any to sell? or maybe there is a work around? I can't find any on ebay and Mouser are really expensive for shipping to Japan.
   
  Thanks, Andy


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## KimLaroux

Quote: 





frodo said:


> I put my amp together today, everything was looking great , I'd even found a working power supply in a junk bin for $2 and some nice 1960's tubes ..... final job mounting the Mosfets to the heatsinks .... Doh! I realised that I don't have any of the ceramic mounting kits. Does anyone know where I can buy them or have any to sell? or maybe there is a work around? I can't find any on ebay and Mouser are really expensive for shipping to Japan.
> 
> Thanks, Andy


 
   
  You mean a TO-220 insulation kit? Like a mica and a plastic shoulder washer?
   
  Here you get 10 kits for 3.50 USD. I'm sure the shipping from Hong Kong to Japan would be reasonable.
http://www.ebay.ca/itm/TO-220-Transistor-Mica-Insulation-full-set-for-TO-220-Transistor-X-10-/261144589902
   
  Otherwise simply search for "to220 insulation" or similar keywords.


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## Fred_fred2004

Quote: 





frodo said:


> I put my amp together today, everything was looking great , I'd even found a working power supply in a junk bin for $2 and some nice 1960's tubes ..... final job mounting the Mosfets to the heatsinks .... Doh! I realised that I don't have any of the ceramic mounting kits. Does anyone know where I can buy them or have any to sell? or maybe there is a work around? I can't find any on ebay and Mouser are really expensive for shipping to Japan.
> 
> Thanks, Andy


 
   
  Dont forget you only need to insulate the heatsinks if they are grounded, if you dont ground them and use a wooden or ABS type case it's not a problem
   
  cheers
  FRED


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## KimLaroux

Quote: 





fred_fred2004 said:


> Dont forget you only need to insulate the heatsinks if they are grounded, if you dont ground them and use a wooden or ABS type case it's not a problem
> 
> cheers
> FRED


 
   
  I beg to differ. Here's two reasons:
   
  First, there can possibly be some 50 volts on these. With the amount of capacitance on the rail, it can be quite a dangerous zap if conditions are met (you just got out of the shower, your feet are wet and your arm brushes the heat sink...). It's simply not something that should be left to chance. Oh and you don't want to be responsible for someone's cat getting killed by such an advice. Not good for business.
   
  If the sinks are not grounded, they become antennas. They'll pick all sort of RF crap that could then be induced on the gate of the fet. Not good. If you ground them, they become shields that actually block RF from reaching the transistors. Much better.
   
  It is therefore preferable to ground the heat sinks and then electrically insulate the transistors from them. It's not that hard to do, and the only argument I can see for not doing it is laziness... at the risk of your own safety... and your cat's.


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## Fred_fred2004

I've never had any problems, but if you want to take the precautions , fair enough
   
  cheers
  FRED


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## Beftus

Got mine today. Looks good. Thanks!


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## marcus76

Got mine too, thanks a lot Howard !!
 Very fast shipping too


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## Fred_fred2004

everybody seems happy no losses so far


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## tcpoint

I'm happy with the board that I got.  It looks great.  Can't wait until work slows down a bit and I'll solder it up.


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## Fred_fred2004

Bump


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## awesomebob

Hi Fred, these sound great, do you have any idea of the shipping time to Italy?
   
  Cheers
  Chris.


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## Fred_fred2004

Hi Chris
  Italy is a challenge it seems to take 2-3 weeks as a letter,
  but there is no hard and fast rule they are all over the place 
   
  FRED


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## awesomebob

Hi Fred, thanks, that's what I thought, OK I'll give a perf board a try and see how I get on..... I saw on your PCB you have C9 and C10, but they aren't in your BOM....


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## Fred_fred2004

Yes thats a mistake 
   
  C2 & C4 are marked on the board as C9 & C10 - WHOOPS 
   
  FRED


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## awesomebob

ah thats ok then! thanks


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## rtfm-now

Hi Fred. Got mine today. Looks perfect.
  Thanks!
 Cheers Rolf


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## jf81

Hi Fred- I'd like to order 2 please!
  PM sent.
  Thanks!
  John


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## kissmeimgerman

Fred,
  Sending you a pm!


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## aleksa

Hi Fred, I would also like to order 2 pcb's please. Sending you a PM.
Thanks, 
Aleksandar


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## jf81

Boards received. Great transaction- Thanks! Now I've got to find time to assemble...


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## kissmeimgerman

Got mine yesterday, Thanks Fred!


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## NeuroCase

Thanks, Fred. I received mine today in the USA. Beautiful board and a smooth transaction at a terrific price. Thank you.


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## HearlParbor

Hey Fred, I'd like to buy one of your PCBs if you've still got some left!


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## Fred_fred2004

sure just pm me your email and country
  
 cheers
 FRED


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## Bob C

Please direct me to the purchase site   Thanks Bob


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## Avro_Arrow

Just PM Fred_fred2004


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## Kaaf

Can anyone post some pictures on how you mounted them in a cabinet/housing?
 Because there are no holes in the PCB to mount it on a standoff and the solder connections are pretty tight to the edge. So clamping them in a tight fit aluminium housing is also no good idea.


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## vixr

sorry, dumb post retracted....


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## DrivenKeys

For anybody interested, the board measures exactly 3"x3". It looks better in person than in the pics, exuding a feel of quality. I'll probably make a plexiglass window in the top of my case, it looks that good. I ordered a 5"x4"x2" aluminum box from Mouser, but after measuring the board, I would have gone with the 4"x4"x2" box.
  
 These and many different sizes of aluminum and steel boxes, in natural and black, are available from Mouser, they just take some searching (Mouser's selection is gigantic) Here's the page in their catalog with links to their respective pages. http://www.mouser.com/catalog/catalogusd/646/2119.pdf  It's the same style of box that n_maher used, displayed in the second post of the original ss thread.


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## xdmkii

What's a good pot to use with this board?


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## DrivenKeys

Any A50K stereo audio taper will do. If you're going to mount it directly to the board, you'll ideally want to order one with 15mm pin spacing. The pot listed in the BOM is from Mouser, and has 12mm pin spacing. I learned this after buying all of the parts and having the board arrive last (no complaints, it was actually quick for overseas). As far as I could tell, Mouser doesn't carry a 15mm pot of the right spec, but don't worry. The pins on the 12 mm pot will easily fit this board with a little bending with some needlenose pliers. The center pins are perfect, and the outside pins need to be bent only 1.5 mm outwards, I can confirm here that the pieces fit in this manner, with just enough length for proper soldering.
  
 In case you don't like bending, or aren't ordering from Mouser, I pm'd Fred about this, and he said that he gets the 15mm pots from ebay.


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## xdmkii

I'll be mounting directly to the board, so that's a huge help. Thanks!


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## domsch1988

Hey guys,

recieved my boards yesterday. Greatly appreciated! They are nicely done and will serve me well. Thanks fred!

Now on to the hard part: The tubes. I just realised, that 19J6 tubes are near impossible to find in europe. And if i'm willing to pay shipping from the US (ebay) they go around 30$ per tube. This is far more then i'm willing to spend on this. I'll keep looking on ebay but in the meanwhile:
Anyone know a source for the tubes around europe (reasonably priced, i'm willing to pay up to 40€ shipping included)?
Alternatively, which Tubes are suitable without changing the layout. I'm fine with changing values all over, as i've not bought anything yet. But i'd like to use the boards. So 7pin is a must and the signal path should be near the same (small changes no problem).

Any ideas on that? I have read the first and last 30 pages of the SS thread. I know that there is a 12au7 variant around. But since this tube is 8pin, it's out of question.

Your help is much appreciated!

Rock on
Dominik


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## Fred_fred2004

I hope you realised the boards are for the 12AU7 not the 19J6 they are just too expensive to use
  
 cheers
 FRED


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## vixr

fred_fred2004 said:


> I hope you realised the boards are for the 12AU7 not the 19J6 they are just too expensive to use
> 
> cheers
> FRED


 
  
 Someone is about to be very happy...


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## domsch1988

Lol... I never thought about counting the holes on the tube sockets... And now that you say it, I just read it in the OP. My bad. And yes, very happy  thanks. I'll report back as I progress!

Gesendet von meinem HTC One X mit Tapatalk 4


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## domsch1988

Hey,
i have to come back at you again. As i'm shopping for tubes, i stuble upon ECC82 tubes. Are they identical to the 12au7 tubes and i'm able to use them or is there a specific difference?

Rock on
Dominik


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## Kaaf

domsch1988 said:


> i have to come back at you again. As i'm shopping for tubes, i stuble upon ECC82 tubes. Are they identical to the 12au7 tubes and i'm able to use them or is there a specific difference?


 
 ECC82 is the european version of the 12AU7 so no problems there


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## dotvibe

quick question, 
  
 Other than the 12AU7 tube instead of 19J6, is this the basic BOM? http://www.diyforums.org/SSMH/bom/SSMH.htm


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## Zashoomin

dotvibe said:


> quick question,
> 
> Other than the 12AU7 tube instead of 19J6, is this the basic BOM? http://www.diyforums.org/SSMH/bom/SSMH.htm


 
  
 Go to the first page and there is a BOM there for the caps and resistors.


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## Kaaf

dotvibe said:


> quick question,
> 
> Other than the 12AU7 tube instead of 19J6, is this the basic BOM? http://www.diyforums.org/SSMH/bom/SSMH.htm


 
  
 Watch out, don't make the same mistake that i did. R2/R8 is 390k for the 12au7 version.
 Just finished mine...working prefectly apart from a slight hum. (maybe some better grounding but WIP). Used a ODAC as a source and a Senn hd600. Clean as a whistle.


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## Fred_fred2004

Bump


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## vixr

...


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## eroline

I was given a PCB as a gift, but without doumentation. Is there a schematic and stuffing diagram for the PCB?
  The PCB is a light green with a dark green solder mask. has provision for 6 pin pot on the top side and has  X10034 as an identifier, 3"x3". I was told it was for a 12au7 version of the design, not for the 19C6 tube.... it has provisions for 2 tubes and 2 mosfets.


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## Fred_fred2004

Have a look at the first post for pictures
 and
 The official staving student thread for schematics
  
 cheers


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## xdmkii

I've got most of the BOM stuff in a cart on mouser, but they don't appear to stock tube sockets. Would this be appropriate? Oh, and those leads for the MOSFETs, anyone know where to get those?


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## Fred_fred2004

Those tube sockets are fine, the lead for the mosfets are just wires soldered on and covered with heat shrink
  
 cheers


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## AxelCloris

I'm eyeing this board myself. I'm a bit curious, how much did the one you have pictured cost to make?


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## Fred_fred2004

If you mean the board on the first page, it was mostly parts I had laying around the place so giving an accurate cost would be hard $20-$30 at a guess 
  
 cheers
 FRED


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## eroline

I had sockets on order from china, I had everything else.  I stuffed mine for 24volt operation, Wes did his for 48volt supply.
 Thanks for everyones support!!!!!! I have a hard time finishing someone else's design. I've just been building my own designs for years so I have full understanding of each component.


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## eroline

We built 2 boards over the weekend, one for 24 volt and one for 48 volt.  I used a 12au7 for the 24volt version and it works good. I upped the coupling caps, used 1/4watt resistors to stuff the PCB.


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## RealSpark

Just to check with you guys about grounding the metal enclosure. 
 Is it just connect the Ground from the DC power supply? I know the center of the powert jack is positive 48V, then the outside of the jack is GND or Negative?


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## Kaaf

realspark said:


> Just to check with you guys about grounding the metal enclosure.
> Is it just connect the Ground from the DC power supply? I know the center of the powert jack is positive 48V, then the outside of the jack is GND or Negative?


 
 Correct. It doesn't really matter where you ground the housing, als long as is not your main ground lead. Always hardwire your grounding.


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## HighMasterGogo

Hi guys,
  
 Are there any PCBs left?


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## RealSpark

What do you mean "main ground lead"? Can I just get a wire connect between the housing and the DC jack (outside of course)?


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## RealSpark

kaaf said:


> Correct. It doesn't really matter where you ground the housing, als long as is not your main ground lead. Always hardwire your grounding.


 
 What do you mean "main ground lead"? Can I just get a wire connect between the housing and the DC jack (outside of course)?


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## Fred_fred2004

highmastergogo said:


> Hi guys,
> 
> Are there any PCBs left?


 
 Yes no problems with the boards
  
 cheers
 FRED


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## Kaaf

I mean that you still need to wire the outside dc connector to the PCB


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## eroline

Our PCB's ae stuffed and mine is set up for 12au7 and 24volt supply, sounds very good. Wes is doing a 48volt version ans his supply is still not here.


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## RealSpark

eroline said:


> Our PCB's ae stuffed and mine is set up for 12au7 and 24volt supply, sounds very good. Wes is doing a 48volt version ans his supply is still not here.


 
 Did you change any components' value when using 24v?


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## eroline

The output fets needed a new bias setting to ensure 12 volts to the heaters.
 I left c7 and c8 off , used 1000u caps for B+ bypass ad to couple to the output. That should improve the low end.
 12BH7 tubes can be used to run at 300ma for lower impedance cans, but larger heatsinks are necessary. I did a variant design using 12au7's as the differential input pair, with silicone opamp biasing, "Sand in my Glass project. uses the heater current for fet pull down so it also is black hole quiet, no hum. I left the heatsinks so they could be soldered or screwed to the PCB to secure them. 1/2 heights work well for 24V 12AU7 combo, full heights would be necessary for 48volt or 12BH7 combo. The PCB was toner transfer etched in a ziploc bag.


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## eroline

R2 was changed to 73k  to help account for the VGS of the mosfets chosen. 73k pull up to 24 volts and 220k pull downs to neg. gnd


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## mburgess00

PM Sent


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## fast14riot

As a complete newb to this stuff, and having a PCB on the way, does anyone have a complete BOM for this build? Possibly with upgraded components?


Thanx!

-Xander


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## kchapdaily

Are these still available? if so i'll take two.
  
 Thanks!


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## Fred_fred2004

Drop me a PM with your email and address
  
 cheers
 FRED


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## Sunshine55

I just caught this thread. Did i read you say 3" x 3"? I can't resist the must have. May i send a pm?


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## Fred_fred2004

Yes 3" x 3" 
  
 drop me a pm
  
 cheers
 FRED


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## HighMasterGogo

Just finished my build and WOW loving tube sound. This is my first experience of the sound of vacuum tubes and I love it. I'm using DT770s and to me they feel like they've 'opened' them up. The sound is much more like an open back headphone sound now. Brilliant, thanks Fred!


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## Fred_fred2004

Glad you like it, they are a very simple build for a surprisingly good sound 
  
 cheers
 FRED


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## doors666

I already have an O2, makes sense to still get this? Does this have tube like sound or more SS like sound?


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## 00940

doors666 said:


> I already have an O2, makes sense to still get this? Does this have tube like sound or more SS like sound?


 
  
 Tubey. It has rather high distortion but mostly 2nd and 3rd, so it sounds rather euphonic. See http://www.pmillett.com/starving.htm
  
  
 That's the price for running valves at lowish voltages but it makes for an amp you're never tired to listen to.


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## tomb

00940 said:


> Tubey. It has rather high distortion but mostly 2nd and 3rd, so it sounds rather euphonic. See http://www.pmillett.com/starving.htm
> 
> 
> That's the price for running valves at lowish voltages but it makes for an amp you're never tired to listen to.


 
 Fred's version in this thread uses the 12AU7.  I don't think it's been tested the same as Pete did with the 19J6.  It may have different performance results.


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## 00940

tomb said:


> Fred's version in this thread uses the 12AU7.  I don't think it's been tested the same as Pete did with the 19J6.  It may have different performance results.


 
  
 Due to the topology, the distortion pattern will be largely similar. The exact values might differ but probably not by much (and ltspice agree). I didn't want to sound derogatory. Those are actually pretty good figures for an amp running open-loop and at those voltages. Heck, my monster mu-follower actually has grossly similar thd specs... into 300R (at higher voltage output of course). I like it better than my previous tube amp, which had a lot of feedback, WCF output stage and low distortion.
  
 Furthermore, such a thd pattern doesn't sound wrong to the ear. I had five minutes of fun with ltspice (simulating the 12au7 version). If you remove the cathode bypass capacitor, you cut the total thd from about 0.5% to 0.13%. You also cut gain by two (a benefit rather than a loss imho). However, this reduction goes with a massive reduction in 2nd harmonics (see attached fft, red with bypass caps, green without, 1Vrms into 32r, 20khz), due to local feedback. Some people might prefer that balance in between second and third harmonics but I'd guess that most would prefer the original.


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## tomb

00940 said:


> Due to the topology, the distortion pattern will be largely similar. The exact values might differ but probably not by much (and ltspice agree). I didn't want to sound derogatory. Those are actually pretty good figures for an amp running open-loop and at those voltages. Heck, my monster mu-follower actually has grossly similar thd specs... into 300R (at higher voltage output of course). I like it better than my previous tube amp, which had a lot of feedback, WCF output stage and low distortion.
> 
> Furthermore, such a thd pattern doesn't sound wrong to the ear. I had five minutes of fun with ltspice (simulating the 12au7 version). If you remove the cathode bypass capacitor, you cut the total thd from about 0.5% to 0.13%. You also cut gain by two (a benefit rather than a loss imho). However, this reduction goes with a massive reduction in 2nd harmonics (see attached fft, red with bypass caps, green without, 1Vrms into 32r, 20khz), due to local feedback. Some people might prefer that balance in between second and third harmonics but I'd guess that most would prefer the original.


 
 With respect, you sort of confirmed what I was trying to say.  You can _guess_ certain flavoring from the topology, but with the tube providing the signal amplification, it's pretty much that - a guess - unless you listen to and test the actual article.  Fred's version may, in fact, be better ... or it could be worse.  I strongly suspect the latter is true with the 12AU7 and Fred's resourceful PCB, but it's more than I'm willing to state - _not having heard it_ -  if someone is asking for a sound comparison relative to another amp, LTSpice notwithstanding.
	

	
	
		
		

		
			




  
 Just an FYI, but you might have overstated the significance of the 3rd harmonic as well in Pete's original design - the 2nd harmonic was absolutely dominating.  I'm not trying to be argumentative, but it's important when statements are put out there about the quality of an amp's sound or in a comparison.  When you stated, "It has rather high distortion but mostly 2nd and 3rd ..." it could imply that the amp is harsh, when it's not.  That's because you make no distinction between the levels of the even and odd harmonics.  If I'm interpreting correctly, the 3rd harmonic (odd harmonic) is down by 75dB over the signal - that's inaudible with almost every headphone.


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## 00940

For the sake of clarity (not argument, I swear):
  
  
 Quote:


tomb said:


> You can _guess_ certain flavoring from the topology, but with the tube providing the signal amplification, it's pretty much that - a guess - unless you listen to and test the actual article.


 
  
 I'd rather say that from the topology, you can determine a basic sound (the harmonics relative weight, a distortion rough ballpark range) and changing tubes (as long as they are suitable for the topology) and pcb will only change the flavor at the margin. Whatever the layout and the tube used, no ssmh will sound harsh nor have vanishing thd (unless you make a mess of things or bring it to oscillation).
  
 But, hey, aren't we all striving for those changes at the margin ? So I certainly wouldn't dare to guess if Fred's version will sound better than Pete's. But I'd certainly be willing to say that both will sound quite different from an O2 (and similar one to another compared to the O2).
  


> Just an FYI, but you might have overstated the significance of the 3rd harmonic as well in Pete's original design - the 2nd harmonic was absolutely dominating.  I'm not trying to be argumentative, but it's important when statements are put out there about the quality of an amp's sound or in a comparison.  When you stated, "It has rather high distortion but mostly 2nd and 3rd ..." it could imply that the amp is harsh, when it's not.  That's because you make no distinction between the levels of the even and odd harmonics.  If I'm interpreting correctly, the 3rd harmonic (odd harmonic) is down by 75dB over the signal - that's inaudible with almost every headphone.


 
  
 More for the information of the public than mine...
  
 My comment about distortion being mostly 2nd and 3rd harmonics is as plain as it can be : distortion in ssmh is mostly 2nd and 3rd. No intention to comment on respective levels. I don't see how I could have implied that the amp was harsh while stating in the same post that ssmh are "_tubey_", "_euphonic_", "_amps you're never tired to listen to_" (judgements actually based on the 2nd strongly dominating, as well as experience, having built such an amp).
  
 If you want, we can rewrite it as_ "it has rather high distortion, mostly 2nd harmonic and a bit of 3rd, and nothing above". _
  
 Btw, 3rd harmonics aren't responsible for amps sounding "harsh". Otherwise almost all amplifiers with a push-pull output would fall in that category. You need higher order odd harmonics for things to go unpleasant (5th, 7th). Iirc, about a person out of three actually prefers amps with dominating 3rd (I could dig a reference from Nelson Pass about that).


----------



## tomb

OK - I give up.


----------



## Fred_fred2004

It's just a good fun build 
	

	
	
		
		

		
		
	


	



  
 and cheap


----------



## tomb

fred_fred2004 said:


> It's just a good fun build
> 
> 
> 
> ...


 
  
 Good statement, Fred!  Thanks for your contribution to the community!


----------



## wakibaki

doors666 said:


> I already have an O2, makes sense to still get this? Does this have tube like sound or more SS like sound?




Most people don't really need an amp, however I've got at least 6 different ones, so if it's not going to break the bank and it's maybe going to teach you a bit in the process of building it, why not? And then you're going to know the difference between SS and tube for yourself, if you can hear it.

w


----------



## doors666

In the schematics, I see a single triode being used for each of the channels, but in the build pics and pcbs, I see two twin triodes 12au7 being used. what am i missing here.


----------



## Fred_fred2004

I think you are looking at two triodes but they are in the same tube, have another look you'll see 2 anodes 2 cathodes etc in each tube
  
 cheers
 FRED


----------



## doors666

i expect to see one tube, but in the first post of this thread, the pcb images and completed build pics have two tubes.


----------



## doors666

Ok, I made a mistake, I see that both triodes are being used for a single channel and both the triodes in a tube are shorted to each other.. I dont understand why its done like this though.


----------



## 00940

doors666 said:


> Ok, I made a mistake, I see that both triodes are being used for a single channel and both the triodes in a tube are shorted to each other.. I dont understand why its done like this though.


 
  
 -1- in the original amp, the 19j6 is a dual triode with only one heater for both sections. So, as you use the heater as load, you need one heater by channel, so two tubes.
 -2- a nice consequence is that running the triodes in // reduces the plate resistance by 2, which decreases distortion in the 33K plate load.
 -3- When substituting with the 12au7, which has a pair of 6.3V heaters, you could in theory just use one tube, grounding the middle point of the heaters and using each half as load for one channel at 6.3V. But (and remember, there's nothing important in front of a but), you probably would increase crosstalk, increase interaction from heaters to cathode, increase thd (by increasing ra), increase dissipation in the mosfets by 1.8W each. And the layouts made for the 19j6 have to be redone completely.


----------



## HIFIbox

Are these still available?
 PM sent
 Thanks !


----------



## RealSpark

Just finished my build today. Here are the photos. 
  

  



  
  
 Very wired that the sound on one channel is normal and the other is not. On the other channel the sound is delayed like echo and the base is totally wrong. I have checked all my circuit and did not find anything wrong. Tried to swap the two tubes and nothing changed. 
 Do you guys have any clue about what I did wrong? Maybe I should use less wire? I used two GE 5814A to replace my 12AU7. Very wired that one of my 12AU7 does not work on this build... The heater just won't light up. They both works find on my another single 12AU7 Amp...
 Please help me. Thank you.


----------



## Fred_fred2004

Any chance of better pictures of both sides of the board?
  
 its hard to see how you've wired it up
  
 cheers
 FRED


----------



## AxelCloris

Wow, I love the idea of using a Mac Mini case as the housing on that. So pretty. How much did the whole setup set you back? And where would you pick up the housing like that, just had one lying around?


----------



## Jose C

@RealSpark
  
 In my boards one of the little squares that should indicate ground was wrong, I don't remember now which one it was, input or output, but if you trace the signals on the pcb you can see the mistake.
  
 Looking at the pictures in the first page I think it was the input ground pad. It's actually the one facing the edge of the pcb instead of the one on the silkscreen.


----------



## RealSpark

axelcloris said:


> Wow, I love the idea of using a Mac Mini case as the housing on that. So pretty. How much did the whole setup set you back? And where would you pick up the housing like that, just had one lying around?


 
 I bought all of the parts from China in one shipment. The Mac Mini case is 90 RMB, boy that is authentic mac mini case. I thought it is a fake one initially. The tubes are cost is 28 RMB each, free matching service. I bought one pair plus one for my other 12AU7 amp. A brand new 48V 2A power supply only for 20 RMB. Capacitor, resistors and all the other components cost about 80 RMB in total. Shipment to Singapore is about 40 RMB, only took 3 days and I got them. So in total it is about 60 SGD or 50 USD.


----------



## RealSpark

jose c said:


> @RealSpark
> 
> In my boards one of the little squares that should indicate ground was wrong, I don't remember now which one it was, input or output, but if you trace the signals on the pcb you can see the mistake.
> 
> Looking at the pictures in the first page I think it was the input ground pad. It's actually the one facing the edge of the pcb instead of the one on the silkscreen.


 
 You are right! My output is wrong. I soldered one channel to ground. Now its working totally fine! Cheers mate!


----------



## RealSpark

fred_fred2004 said:


> Any chance of better pictures of both sides of the board?
> 
> its hard to see how you've wired it up
> 
> ...


 
 Its actually the output is wrong. I fixed it. The sound is perfect now. MonkeyD.Luffy is right, the input labelling is wrong. GND should be the outter one. 
 Thanks Fred for the awesome PCB.


----------



## Sunshine55

Howard my boards came today. Thank you. Now the fun starts and just in time for X-Mas.


----------



## scootsit

What PS are you guys using? Would a really HF switcher work if I throw some huge caps, bypassed between +/-?


----------



## doors666

There are no mounting holes. How have you guys mounted it on the chassis.
 The only thing i see is the pot that can be mounted, but is that mounting strong enough to hold the pcb and the tubes. I was actually thinking of ditching the pot, but looks like i might need it... Any issues with a 100k pot. I plan to use this with 32 ohm headphones.
 Any particular reason why i see most of the people mounting the tube sockets on the other side.


----------



## Fred_fred2004

There is plenty of room to drill mounting holes through the board, depending on the enclosure you are planning to use
  
 I have used a 100K pot it seemed to work fine
  
 the board was designed to have the tubes on the track side, if you put them on the other side all the connections will be mirrored - so not going to work 
  
 cheers
 FRED


----------



## longslong

I've seen a few calls/references to a BOM or parts list and having done the homework (and hopefully gotten it right  I created a 12AU7 PCB based list for Mouser.  The link is read only but_* if you see errors there, please let me know and I'll update*_ so future finders of the thread don't have to recreate as it's very easy to make mistakes. In addition to this list, you'll need materials for a case and a 9 pin ceramic tube socket- I got some of the 9mm high ones off ebay and of course a couple of tubes and a power supply.


----------



## RealSpark

Hey Fred, just to check with you. What will be the effects if i change some capacitors?  Like use 2.2uF caps? I have quite a few wima red caps laying on the ground....


----------



## Fred_fred2004

I doubt that it will make any difference in reality. But if you have them around and the voltage rating is sufficient why not use them 
  
 cheers
 FRED


----------



## muskyhuntr

Hi,
 I've seen both 24V and 48v used as power sources for this amp.  Which is proper?
 Thanks


----------



## Fred_fred2004

The 48V is the one to use
  
 cheers
 FRED


----------



## Can Junkie

Fred/ Guys, do you think this PS would work? I want to build the PS into the case.
  
 It is a switching type rated at .313a at 48V DC
 (I think the orig SS used 350ma wall wart with a plug cord)
  
 http://www.mouser.com/ProductDetail/Mean-Well/RS-15-48/?qs=sGAEpiMZZMsi5STK09QP%252bCkHnllB9KyW


----------



## Beftus

The original used a .38A (or 380mA) PS. The .313A might not be enough to get it up and running. You planning on using some LEDs with it? Power LED, tube LEDs? The tube heater draws 150mA of current, and since you have two tubes both will draw 300mA of current. Throw in a LED or two tube LEDs and your proposed PS runs out of juice pretty fast.


----------



## Can Junkie

beftus said:


> The original used a .38A (or 380mA) PS. The .313A might not be enough to get it up and running. You planning on using some LEDs with it? Power LED, tube LEDs? The tube heater draws 150mA of current, and since you have two tubes both will draw 300mA of current. Throw in a LED or two tube LEDs and your proposed PS runs out of juice pretty fast.


 

 Yeah I was a thinking along those lines too. Just needed to hear it from another. I'm an overbuild type guy myself when it comes to that type of stuff. It is a neat little rig. Maybe I can find a bigger one just like it. If I do, I will post it.


----------



## Can Junkie

Ok, here we go guys:
  
 PS for SS Board:
  
 less than $13, switching type 86 to 240V ac input, 48VDC at .75 amps!
  
 Is there any reason why this switching PS mounted in the case, would not work??
  
 http://www.trcelectronics.com/View/Mean-Well/EPS-35-48.shtml


----------



## Fred_fred2004

That looks like a reasonable choice, dont forget on the original design of the SS the power supply was effectivly overloaded while the heaters were cold and it would cut out and cycle a couple of times, so they are pretty tough
  
 cheers
 FRED


----------



## Can Junkie

fred_fred2004 said:


> That looks like a reasonable choice, dont forget on the original design of the SS the power supply was effectivly overloaded while the heaters were cold and it would cut out and cycle a couple of times, so they are pretty tough
> 
> cheers
> FRED


 

 I was hoping it might be large enough to avoid the unit going into overload. (hope it auto resets)If each heater only draws 150ma I should be ok. I would have say 300ma left over with 100ma for other sys draws.


----------



## Beftus

Should be ample current for it. Enough for adding a bunch of LEDs too.


----------



## Can Junkie

beftus said:


> Should be ample current for it. Enough for adding a bunch of LEDs too.


 

 I think this is the one I will go with. 90 to 260ACV input.
 A whopping  1.36A at 48VDC. Only $15.50. This baby will be loafing in the SS no matter how many LED's are used.
  
 http://www.trcelectronics.com/View/Mean-Well/EPS-65-48.shtml


----------



## dallen9494

Hi,

I would like to buy 3 of your boards if they are still available.

Thanks,
Dennis


----------



## Fred_fred2004

PM'd
  
 cheers


----------



## dustinsterk

For anyone looking for a power supply...I literally have 100's of the cisco power adapters for sale.  I would sell them for $10 if you are interested.  Just send me a PM.
  
 They are Cisco part number:  34-1977-03       48V, .38A
  
 Thanks!
 --Dustin


----------



## kclarksville

I looked through your list and noticed that C3A and C5A are 250 v rather than the 63v mentioned in Fred's BOM.  Thank you for your time and work by the way, it made a big difference. Take care


----------



## muskyhuntr

Hi All;
  
 A few pages back there was a post or 2 asking about a pot that would fit the PC board.  PN# 652-PDB182_K430K-503A from Mouser fits likke a glove.
 It's a Bourns, 50K audio pot.
  
 Jim


----------



## darkarn

Just finished soldering all parts... only to be able to hear only from the left channel, right channel giving me loud humming noises. I have checked all contacts and replaced the opamp and LM317 which helped a bit. What should I do next?


----------



## Fred_fred2004

You need to post some pictures
  
 what opamp??
 LM317??
  
 cheers
 FRED


----------



## Fred_fred2004

Now, I see you are building another kit not the SS
  
 we can sort it via email
  
 cheers
 FRED


----------



## darkarn

fred_fred2004 said:


> Now, I see you are building another kit not the SS
> 
> we can sort it via email
> 
> ...


 
  
 Yeah, sorry for making it unclear earlier; check out your email in a while, just took some pictures of what I did


----------



## Can Junkie

Hi Fred, Boards arrived the other day, they look great,..thanks!!
 Questions:
  
 (some may seem simple, but just want to make sure)
  
 1) On the transistors, the thinner area denoted by the dotted line is the heat sink side for orientation purposes?
  
 2)The 3 terminal phone plug is the one connected to R16 and R17 which go to the vol pot? The input is connected to R12 and R6?
  
 3) I plan on "Earth" grounding the metal case. (round pin on US AC outlet) If I do this, do the heat sink(s) need to be insulated from the metal enclosure? Also can I use one big Heat Sink or do they need to be separated. (If yes, answer to first Q of # 3 is yes.
  
 4) The 2 pins that go to C6 and C3 are the 48V DC input?
  
 5) If I do # 3 above, do I have to make sure I insulate the outer common grounds of the phone jack and the input. (Prob yes)
  
 6) As long as the mounting threads of the Vol pot are insulated from all 6 pins on it (I think it will be) I will be ok using the threads to mount the Board, pot to the "Earth grounded enclosure
  
   Thanks again for all your help from all of us DIYers.


----------



## Fred_fred2004

can junkie said:


> Hi Fred, Boards arrived the other day, they look great,..thanks!!
> Questions:
> 
> (some may seem simple, but just want to make sure)
> ...


 
 cheers
 FRED


----------



## dustinsterk

Got my two boards today!  Thanks again!


----------



## Can Junkie

Any reports from builders as to how this amp sounds?  I kind of need to know before I decide if I want to spend some extra cash on a Hammond enclosure or not. I am particularly interested as to if the amp does a good job of bringing out the highs and lows. I have found most non amped sources as well as HP's tend to fall off the further you get from the mids. I am building two units, one for my self and one for my sister, The last thing I want to do is put too much money into the units, only to find it just sounds a little louder with no significant improvement in the highs and lows.
 Thanks,....Eric.


----------



## dustinsterk

There are lots of opinions of this amp from the original thread found here:
http://www.head-fi.org/t/319231/millett-starving-student-hybrid-amp/6690
  
 My 2 cents is that with the proper headphones and source (in my case a HD600's and a modi DAC from schiit audio), it sounds wonderful.
  
 All in all it should cost you less than $100 to put an amp together if you do some shopping around (including the tubes).
  
 Good luck with the builds!
  
 --Dustin


----------



## dustinsterk

I have posted a quick link for ordering from Mouser (one of my projects)....you will still need the tube sockets and tubes:
  
*http://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=def7402dc6*
  
 Hope this helps anyone that needs it...or the lazy.


----------



## Fred_fred2004

Thanks for the list
  
 I'm one of the lazy ones


----------



## bristto

Thanks Fred!
 Just received my PCB...
 Lovely board, amazing value & and super speedy delivery from the other side of the world!!
 Now to start building


----------



## ximamp

HI I would be interested in a couple of boards if you still have some available.
 Thanks,
 Antonio


----------



## Fred_fred2004

no problems pm your email address
  
 cheers
 FRED


----------



## bristto

Quick newbie question - on Fred's board, where do I connect the LED's for the 2 tubes and the rled to go with it? 
Thanks...


----------



## Fred_fred2004

I just air wire an LED and series resistor from the main power after the switch and the ground
  
 across C6 on my board is as good a place as any
  
 cheers
 FRED


----------



## dustinsterk

Has anyone every completely got rid of the hum when you touch the volume POT?  It is so minor but annoys the hell out of me.  I have tried to ground it directly, but without any luck.
  
 I was thinking of insulating the pot from the stainless volume knob...not sure if that will completely fix the problem, but worth a shot.
  
 Thanks in advance.
  
 --Dustin


----------



## scootsit

dustinsterk said:


> Has anyone every completely got rid of the hum when you touch the volume POT?  It is so minor but annoys the hell out of me.  I have tried to ground it directly, but without any luck.
> 
> I was thinking of insulating the pot from the stainless volume knob...not sure if that will completely fix the problem, but worth a shot.
> 
> ...


 

 Is there a grounding screw on your pot? The Alps pots in the plastic cases have a grounding screw. Else, ground the case. Is it in a metal case?


----------



## Jawmare

So just for your information, nichicon caps on the original bom are too large for this pcb. Don't make the same mistake as i did.


----------



## drabina

jawmare said:


> So just for your information, nichicon caps on the original bom are too large for this pcb. Don't make the same mistake as i did.


 
 Little more info? What original BOM? The one from the original SS thread or the one posted here in this thread?
  
 I am about to order all parts can still make substitutes.
  
 Thanks.


----------



## Jawmare

drabina said:


> Little more info? What original BOM? The one from the original SS thread or the one posted here in this thread?
> 
> I am about to order all parts can still make substitutes.
> 
> Thanks.


 

 Use the part list posted in this thread.


----------



## dustinsterk

scootsit said:


> Is there a grounding screw on your pot? The Alps pots in the plastic cases have a grounding screw. Else, ground the case. Is it in a metal case?


 
 There is not a grounding screw but the POT is metal so I tried to ground the entire thing.  The case is also metal so I did ground it as well.  The noise is much quieter but not dead quiet.  It is more of an annoyance than anything...


----------



## dustinsterk

You can find my BOM here....I have made two amps from these exact parts and the fit is perfect.
  
 https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=def7402dc6


----------



## Greystoke

I've got the bits and parts for the Jonokuchi project on the way, but I'd be interested to try out this build as well.  Can I order a couple of PCBs?


----------



## Fred_fred2004

yes pm your details


----------



## scootsit

dustinsterk said:


> scootsit said:
> 
> 
> > Is there a grounding screw on your pot? The Alps pots in the plastic cases have a grounding screw. Else, ground the case. Is it in a metal case?
> ...




In my experience, sometimes that just happens. It may be that the pot case isn't super conductive, and grounding isn't going to work.


----------



## drabina

Anybody have Mouser part #s for the terminal blocks that would fit this PCB? I would prefer terminal blocks with a screw vs. the ones pictured on the first post.
  
 Thanks.


----------



## Jawmare

drabina said:


> Anybody have Mouser part #s for the terminal blocks that would fit this PCB? I would prefer terminal blocks with a screw vs. the ones pictured on the first post.
> 
> Thanks.


 
 571-282834-2
 571-282834-3


----------



## dustinsterk

Scootsit....thanks for your input!  I guess a little hum when I touch the knob is no big deal.


----------



## wastaner

I think you can order this PCB assembly from China,the price is reasonable and the quality is well too.www.wonderfulpcb.com and www.pcbcart.com are often I am ordered.hope can help you


----------



## Greystoke

Got my PCB on Monday, thanks!  Quite a bit smaller than I expected, still thinking of case options but it should fit just about any small case.


----------



## Greystoke

A quick question for people who used non-metallic cases.  I'm looking to make a case from wood, with metal plates for the top and bottom.  Do I need to make sure all the metal bits are grounded to each other?  I've seen several references to grounding issues, and since the default project case is metal I wasn't sure what was required.


----------



## muskyhuntr

There's been some talk in this thread and else where about a switching power supply's affect on the performance of an amp.  I was thinking of throwing a small board together to 'smooth' out the supply on my Starving Student.  What do you guys think about a pair of 220uF electrolytics and a .1 or .01 film for this.  Any thoughts on these values or its over all worth in general?
  
 Thanks,
 Me


----------



## robump

How do i go about ordering a couple of these?
  
 Thanks


----------



## Fred_fred2004

You ask me 
  
 cheers
 FRED


----------



## robump

PM Inbound!


----------



## robump

Received today. Thank you very much..... will get on with ordering the other components and let you know how i get on!
  
 Any tips?


----------



## fuens

Hi mates.
 I begin to build an SSMH amplifier.
 I wish to know what configuration you recommend to me for a SSMH 12au7:
 10K pot and R16 & R17 10K or prefer 50K pot and R16 & R17 50K?
 I will use for headphones from 80ohm up to 250ohm.
 Thanks on advance.
  
 Cheers
  
 toni
  
 P.D.(If you can tell me pros and cons, thanks   )


----------



## Fred_fred2004

Someone else posted this and it's a very reasonable explanation
  
_~~Adding a 50K resistors before a volume pot virtually lengthens the resisting surface by 50K. Say you have a 50K pot that you never go over half its rotation range. Adding a 50K resistor before pushes that useless half outside the rotation range (not really on a log pot, but you get the idea). It's effectively stretching the first half of the pot across its whole rotation range. The value isn't important, you chose it after experimenting with your system until you find the right value. It depends on the voltage out of your DAC and the voltage your headphones need._
  
 I use 50k or 47K just make sure you use LOG pots
  
 cheers
 FRED


----------



## fuens

Thanks so much Fred. 
	

	
	
		
		

		
			




  
 Cheers
  
 Toni


----------



## Jawmare

So after everything was built, it appears that only the left side is working (right tube doesn't light up and no heat from right mosfet).
  
 Things I tried:
  
 swapping tubes - tubes are fine
 resistance/continuity test - so far no problem found
  
 Any idea from here?


----------



## Fred_fred2004

You need to put up some pictures otherwise it could be lots of things
  
 both sides of the board
  
 cheers
 FRED


----------



## Jawmare

http://imgur.com/a/ctTEu
  
 Problem fixed, despite me reminding myself that I need to solder the MOSFET the right way I still manage to f it up.


----------



## robump

Can anyone recommend a Pot that is available in the UK?
  
 I have tried to find a stockist for the PDB182-K430K-503A but they all seem to charge £12 shipping from the US!
  
 Thanks


----------



## fuens

Hello
 Try to found it on Ebay.
 Sure you will find more cheap (item + delivery).
 Have luck.
  
 Cheers
  
 Toni


----------



## Jawmare

Is it normal that after amping vocal shifted to the left?


----------



## muskyhuntr

Hi All;
  
 Finally finished my Starving Student.  If I had to describe this project with one word, it would be 'surprise'.  With no break in, this thing sounds good even with my cheap break in phones.
 Here are a few pictures of the final product.
  
 Me


----------



## Fred_fred2004

Very neat job, well done 
  
 cheers
 FRED


----------



## KimLaroux

fred_fred2004 said:


> Someone else posted this and it's a very reasonable explanation
> 
> _~~Adding a 50K resistors before a volume pot virtually lengthens the resisting surface by 50K. Say you have a 50K pot that you never go over half its rotation range. Adding a 50K resistor before pushes that useless half outside the rotation range (not really on a log pot, but you get the idea). It's effectively stretching the first half of the pot across its whole rotation range. The value isn't important, you chose it after experimenting with your system until you find the right value. It depends on the voltage out of your DAC and the voltage your headphones need._
> 
> ...


 
  
 Thank you.


----------



## greg1975

Fred - Do you still have boards left?  I'm thinking of picking up 2 or 3 of them.
  
  
 Has anyone compared the sound on the 12AU7 version versus the 19J6 version?
  
  
 Thanks all!
 Greg


----------



## Fred_fred2004

Hi Yes got plenty  Boards are $3.75 each postage in Australia is $1.50
  
 worldwide airmail $3.00 for up to 2 boards, then it jumps to $7.00 for up to 250g
  
 send me your email address plus the number you want and I'll send a Paypal invoice
  
 cheers


----------



## fuens

Thanks Fred!

 Also thanks to Pete Millet and Doug Savitsky.
 Another Starving Student amp on this world.
 Sound great! Detailed and powerfull!!!
 Cheers


----------



## RBWDash

If you have any PCB's left, I would like to buy two of them.


----------



## Fred_fred2004

No problem, PM me your email address and country
  
 cheers
 FRED


----------



## KimLaroux

fuens said:


> Thank you Fred!
> 
> Also thanks to Pete Millet and Dsavitsk.
> Another Starving Student on this world.
> ...


 
  
 You're using a bridged dual 24 V supply to get the 48 V to power the unit? Have you had any issues with this setup? I've thought about it but figured the lack of proper ground could be an issue.


----------



## fuens

Hi Kim.

 I've thought a lot about the power supply (I was going to build one myself), I finally found this on ebay seller. attached scheme.
 For personal safety, connect the ground (from socket) to the chassis of the amplifier (not from the negative power supply, not from chassis power supply).
 Now the power supply is under testing, requires more heat sink that is working to the limit, according to specifications (heat sinks are really hot)
 I'm waiting for some additional heat sinks.
 The power consumption is 0.296 A as seen in the picture.
 I'll report, if you have any questions please write me.

 Cheers
  
 P.D. (This is very dangerous, not anyone can do this without electrical knowledges, possible shock damage, here we have 220 ​​volts AC and many capacitors!!!)


----------



## DingoSmuggler

If using a dual 24V supply, take the output ground from the 0V of the power supply.
  
 EDIT: you will also need to put the bleed resistors for the output caps to 0V also, so disconnect them on the pcb, but put them across the headphone jack. These are R6 and R12 on the pmillet.com schematic.


----------



## fuens

Hi
 I do not understand the modification that you say.
 Ground is earth, negative is negative
 Take power from + and - . There you has 48v.
 This power supply is +/-24V based on 7824 7924. (do not use the output GND from PSU is not a real ground, is one midpoint voltage)
  
 If the matter is some noise from the pot, solder the negative to the chassis pot. No more modifications.
 The ground from socket is for AC protection (leakage), but must not be connected to negative only to chassis of amplifier (metal box).
  
 Cheers
  
 P.D. (if you wish we can open a new thread, will be more appropriate)


----------



## Jawmare

After 6 weeks of work, here is my SSMH with Hitachi 17EW8
  
 http://imgur.com/a/dIT3M


----------



## KimLaroux

The output jack is AC coupled, as the output goes trough a capacitor. What he's saying is, you need to connect the output jack's return to the 0V rail, not the -24 V. Otherwise you're biasing your headphones to - 24 V.
  
 In your current setup, the drivers are modulating around -24 V instead of 0 V. It works but it's dirty. It's also unsafe as the jack's sleeve is -24 V and not 0 V.
  
 You also need to connect the output capacitor's bleeding resistors to 0V and not -24 V, otherwise you will create a short.


----------



## fuens

Capisce 
	

	
	
		
		

		
		
	


	



  
 Cheers


----------



## nzhao20

You have to drill your own holes for the tube openings and such if you want to use this in an enclosure right?


----------



## Tequilasunriser

nzhao20 said:


> You have to drill your own holes for the tube openings and such if you want to use this in an enclosure right?


 
 Yup.
  
 I think this is going to be the most difficult part when I build mine as I don't have a drill press or anything and I'm pretty sure I'll screw up the positioning/alignment too haha.
  
 Yeah, I'm not looking forward to drilling those holes...


----------



## Fred_fred2004

There is nothing stopping you mounting the tube sockets on the case and running wires to the pcb, if you are concerned about drilling holes
  
 cheers
 FRED


----------



## lucho-mex

Hey Fred beautiful work on the boards! Can you tell me the dimensions they have?


----------



## Fred_fred2004

Hi the boards are about 76mm square
  
 cheers
 FRED


----------



## J201

Wow! This is exactly what I was looking for! Thanks! Fred, I'll send you a PM in just a minute!


----------



## rudolfstrander

Thanks so much for doing this! Just sent you a PM!


----------



## Fred_fred2004

bump


----------



## tigman9

Hey all I need some help here, I'm having some issues and I don't know what from, I have everything hooked up according to the pictures and all the right parts but when I turn on my amp all I get is sound from the left channel, the right tube heats up, the left does nothing and the right channel has nothing, and when I fiddle around with stuff place the volume gets much louder and gets a buzz, which happens when I fiddle with the volume pot a bit but might be from the tube shifting slightly, this is my first build so please give me any pointers, thanks
 (note: if you need anymore pictures ill take some more)
 Link to pictures: http://1drv.ms/1iGToDm


----------



## fuens

tigman9 said:


> Hey all I need some help here, I'm having some issues and I don't know what from, I have everything hooked up according to the pictures and all the right parts but when I turn on my amp all I get is sound from the left channel, the right tube heats up, the left does nothing and the right channel has nothing, and when I fiddle around with stuff place the volume gets much louder and gets a buzz, which happens when I fiddle with the volume pot a bit but might be from the tube shifting slightly, this is my first build so please give me any pointers, thanks
> (note: if you need anymore pictures ill take some more)
> Link to pictures: http://1drv.ms/1iGToDm


 
 Hello tigman9
 1st I can see: in photo IMG_350 the input is different than photo 20140627_212046210_iOS (in this photo looks correct)
 CHECK the input
 2nd I can't see the connections of mosfets, tubes. Each one are warm?
 CHECK with the drawing and multimeter (continuity mode) each channel
 Also you can check the tube sockets.
 Have luck
  
 Toni


----------



## savagetuna

If you've still got any of these I'll take 2!


----------



## savagetuna

Also, this is like the normal SSMH in that you need to unplug your headphones before turning on and of correct?


----------



## Fred_fred2004

No problems PM me your details
  
 cheers
 FRED


----------



## pranavkumar

Do we still have some PCBs ? I'd like to get two.


----------



## Fred_fred2004

Yes PM me your email and country and I'll send an invoice
  
 cheers
 FRED


----------



## haishaul

Hi ,
 would like to buy 3 boards if possible .
 Thanks !


----------



## treffynnon

Here is my build with the Fred_fred2004 PCB into a Hammond 1590XX enclosure. Surprisingly it's quiet even with my octapus like wiring on the tube sockets.


----------



## Amatsu

That looks like a nice heatsink. Does it still get hot with that thing?


----------



## treffynnon

Yeah, it still gets pretty toasty - bearable to touch. It's a 100x~100 and cheap.

http://uk.farnell.com/fischer-elektronik/sk-04-100-sa/heat-sink-100mm/dp/4621529


----------



## aemos

I would like a board as well. Will PM you the details now.
  
 Thanks!


----------



## Ocean7

Fred I would like to purchase two boards please. Just sent you a PM.
  
 Thanks


----------



## lybbert

PM sent about pcbs
  
 0dd


----------



## Fred_fred2004

In answer to all the questions, yes I have boards available 
  
 cheers
 FRED


----------



## aemos

I just got the PCB by mail to Denmark. Looks perfect. Thanks a lot!


----------



## Amatsu

Yeah I got mine today as well. Time to work.


----------



## Amatsu

It feels so good soldering in one of these...Doing a p2p build the first time was a good learning experience but I'm never doing that again.


----------



## Ocean7

Just got the boards and they're very nice. Thanks Fred Fred!


----------



## Ocean7

amatsu said:


> It feels so good soldering in one of these...Doing a p2p build the first time was a good learning experience but I'm never doing that again.




Something went wrong? I really enjoy building P2P. It's like a challenging 3D puzzle and you can be very creative solving it.


----------



## drabina

treffynnon said:


> Here is my build with the Fred_fred2004 PCB into a Hammond 1590XX enclosure. Surprisingly it's quiet even with my octapus like wiring on the tube sockets.


 
 That's what I wanted to ask about here on this forum. I need to add wires between tube sockets and PCB (about 2" long). Can I just add single wires or they should be twisted in pairs (or all)? Also, once in the enclosure, the wires are not going to be stretched but cramped. Would that cause a problem?


----------



## Ocean7

drabina said:


> That's what I wanted to ask about here on this forum. I need to add wires between tube sockets and PCB (about 2" long). Can I just add single wires or they should be twisted in pairs (or all)? Also, once in the enclosure, the wires are not going to be stretched but cramped. Would that cause a problem?




There is no need to twist the wires imho. Cramped wires are not a problem neither. It's going to be easier to build all together if you use stranded wires.


----------



## treffynnon

I braided them to make it neater and spread any physical load over more than one contact point to the PCB. As you can see the enclosure I used is quite small in terms of height so all that wiring you see under the tube socket is simply crammed in. I had expected there to be noise and to have to re-do it, but it's nice and quiet.


----------



## Amatsu

Hey muskyhuntr, what do you use for the words on the case? It looks neat. Also do you use a led for the power and if so where does it go in the pcb?
  
 Quote:


muskyhuntr said:


> Hi All;
> 
> Finally finished my Starving Student.  If I had to describe this project with one word, it would be 'surprise'.  With no break in, this thing sounds good even with my cheap break in phones.
> Here are a few pictures of the final product.
> ...


 
   
 Not at all, it's just I prefer the 2D puzzle myself at least for now, maybe because it's easier. Also feels more sturdy with a pcb.
  
 Quote:


ocean7 said:


> Something went wrong? I really enjoy building P2P. It's like a challenging 3D puzzle and you can be very creative solving it.


----------



## muskyhuntr

The lettering on both the front and rear panel was done by Front Panel Express, who also did the metal work.  The LED is connected to the power input at the switch.  You can barely see where the resistor is on the right. It is covered in shrink wrap.
  
 Me


----------



## Amatsu

Well I've re-build the amp with the new pcb into a small cardbox until I can make or find a decent enclosure. It finally sounds alright! I knew there was something wrong with my p2p build, it sounded very harsh, now it's totally different. I'm really glad I bought the PCB, thanks again Fred.
  
 I'm also thinking of getting a new pot because mine doesn't fit in the PCB and I'd like to avoid cables if possible.
  
 http://www.ebay.com/itm/1-x-100K-Ohm-B100K-LINEAR-DUAL-TAPER-POTENTIOMETER-Pot-17mm-Shaft-Free-Shipping-/321435832488?pt=LH_DefaultDomain_0&hash=item4ad71190a8
  
 Do you think this one will fit with the PCB? I can't find much info on it.


----------



## Fred_fred2004

The size is right but the taper needs to be LOG
  
 cheers
 FRED


----------



## Jo-Sur

search for "Alpha 100k stereo log".Is the best choice for this amp.is a little expensive but have perfect quality


----------



## Ocean7

Hey Fred_fred,

Just finished my build but I still need to put everything in an enclosure. Sounds sweet!

Quick question : I am using the exact same heatsinks as the ones shown in the pictures but they get real hot. After 5 minutes it's impossible to touch them. I'm guessing this is normal? Any long term issues with your build? Should I go for bigger heatsinks?

Thanks,

Ph.


----------



## Jo-Sur

the operating temperature for irf510 is 175c.Is normal.i have the same heatsink.If you use box dont put them inside the box.and dont forget to put thermal paste between.upload some picture to see your construction 

```
[left]  [/left]
```


----------



## Ocean7

Here is what it looks like so far waiting for its enclosure


----------



## Jo-Sur

goodits work fine?the sound quality? what irf510 is that?


----------



## Ocean7

Thanks. It works fine. No noise, no issue at all. I did not listen to it a lot yet but as far as I can tell it sounds very nice.

It's the IRFI510 (Digikey IRFI510GPBF-ND). Same as an IRF510 but in an insulated package so no need to play with mica insulators


----------



## NCSUZoSo

I read the first page and the last page and I've read enough on the design to know that I want to build one.
  
 Are PCBs still available for purchase?


----------



## Jo-Sur

hi.i finish my build today but i have little problem.the right channel the sound is a bit poor,for example the sound of voices not heard much,i measure everything,i change resistors and transitors i swap tubes but nothing.the only strange is that the pin 5 of tube the left have 19v and right have 11,6v.the other measures have normal difference between and parts and pins.any idea???thnks


----------



## Ocean7

Here is my Fred_fred 12AU7 SSMH. Sorry for the bad picture I need to take better ones in good light!

That thing sounds great. I am most impressed if I say so myself.


----------



## Jo-Sur

beautiful construction where buy that box?what manufacture dimmension have?


----------



## Ocean7

Thanks. 

That's a Hammond clone that I got from Mammoth Electronics http://www.mammothelectronics.com/4S1590BBT-p/500-1004.htm


----------



## EniGmA1987

If I wanted to use this amp with just a single mono input, and output to both left/right headphone (still mono signal since 1 input) could I basically just have the one input go into a mono potentiometer and the output for that would go into R14 and R15 and leave everything else the same? Im looking at this schematic posted a couple pages back that I assume is the same design as the PCB boards:
http://cdn.head-fi.org/9/90/90ff3244_SSMH-SCHEMATIC-12AU7.gif
I want to use this as a cheap little tube amplifier for coming line out of an electric guitar and to amplify the signal so it can be listened to on headphones nicely for nighttime playing.


----------



## drabina

enigma1987 said:


> If I wanted to use this amp with just a single mono input, and output to both left/right headphone (still mono signal since 1 input) could I basically just have the one input go into a mono potentiometer and the output for that would go into R14 and R15 and leave everything else the same? Im looking at this schematic posted a couple pages back that I assume is the same design as the PCB boards:
> http://cdn.head-fi.org/9/90/90ff3244_SSMH-SCHEMATIC-12AU7.gif
> I want to use this as a cheap little tube amplifier for coming line out of an electric guitar and to amplify the signal so it can be listened to on headphones nicely for nighttime playing.


 
 I am not an expert, but I would populate only half of the board and use one tube and one MOSFET. No need to have both tubes and MOSFETs running to process the same signal. You would spend only half of the parts money. That of course unless you want to rebuilt it later for stereo use.
  
 Even cheaper would be something like this: http://www.kitsrus.com/pdf/k87.pdf. I have built this amp into a small plastic enclosure and run my guitar thru that. It worked just fine with my 600 Ohm AKG cans. But that's a bit off topic.


----------



## benoitmabille

Hello,
 This is an old thread.. 
	

	
	
		
		

		
			




 However, if there are 1 or 2 PCB available (12AU7 or 19J6 version), I would be happy !
  
 Thanks in advance.
  
 Benoit
 (Brussels, Belgium)


----------



## Fred_fred2004

I have plenty of the 12AU7 pcb's
  
 cheers
 FRED


----------



## AXLM

Hello,
  
 I also am interested in 2 or 3 pcb's for the 12au7 so I have send you a pm Fred_fred2004.
  
 cheers!


----------



## kozmos

What power adapter do you guys use with this pcb?


----------



## Fred_fred2004

Use the Cisco 48V power supply just the same as the original design
  
 cheers
 FRED


----------



## Ocean7

fred_fred2004 said:


> Use the Cisco 48V power supply just the same as the original design
> 
> cheers
> FRED




Same here. I got mine off eBay, item 371015023668

Works perfectly. No noise at all.


----------



## LG2015

I'd love to get one of these 12AU7 pcbs if you still have any left. I am going to PM you now Fred_fred2004.
  
 Thanks in advance!


----------



## Fred_fred2004

Plenty of boards left


----------



## Wisor

I would like to order one PCB.
  
 You have a private message 
  
 Regards,


----------



## LG2015

I received the pcb on Saturday. It looks good! I can't wait to build this thing! I'm just waitng on a few more parts. Thanks again.


----------



## Wisor

PCB arrived yesterday and it looks great!
  
 Today I went to local electronic shop and I bought most of elements they had on stock.
  
 I didn't get 0.22UF and 680UF 63V caps.
  
 Shop owner ordered them, and I should get them probably in the end of next week.
  
  
  
 Are these mosfets OK or do you recommend some others ?
  
 http://www.mouser.com/Search/ProductDetail.aspx?qs=sGAEpiMZZMutXGli8Ay4kCPNvF3z2OenR4h57KMXrK4%3d


----------



## DaemonSire

ocean7 said:


> Here is my Fred_fred 12AU7 SSMH. Sorry for the bad picture I need to take better ones in good light!
> 
> That thing sounds great. I am most impressed if I say so myself.


 
  
 That's great.  If possible, could you take a picture of the inside?


----------



## urshurak776

Hi everyone. What size wire do you recommend? 20 gauge, 22 gauge?


----------



## urshurak776

Seems the 2W 2.4kohm resistor on Dustin's mouser project is only available in quantities of a 1000. Same with the knob. You guys have any ideas? I can't wait to build this


----------



## Wisor

I couldn't get capacitators C1 and C6 (680UF) so I used 470UF 63V I had. I hope it won't effect the audio 
  
  
 I have a question about potentiometer.
  
 I couldn't get a potentiometer that fits on PCB in local store.
  
 Probably I would have to order it from mouser or farnell.
  
 Which one did you guys use, do you have any tips about buying one ?
  
  
  
 I still need tubes and tubes sockets. Gonna order it from ebay soon.
  
 now i am working on enclousre. Its gonna be made out of plywood


----------



## urshurak776

Going through my parts, I have two IRL510's. Would these be okay to use?


----------



## urshurak776

Got my boards today! Thanks Howard!


----------



## GirchyGirchy

Sent a PM earlier for a couple....looking forward to building this!


----------



## Wisor

Cheers!
  
 My project stopped for a bit. I still need a potentiomete (I don't know which one to order), Tubes and sockets for them.
  
 At the moment I am working on CmoyBBs


----------



## TattooedMac

I will have a couple of boards, Fred, if there is any left. PM Sent.
  
 Cheers


----------



## GingerBeard

Thanks, Fred!  Board looks great!


----------



## brokentofu

I would like to purchase a few of these boards. Do you accept google wallet or paypal?


----------



## Wisor

Hey, 
  
 Started to work on project again.
  
 Ordered a PS on Ebay from China, it's on the way. Also talked with some audio company for tubes and sockets. I ordered JJ tubes for 7€ each +22% tax. Neightbour who is making cases out of sheet metal will make me an inox box and I will apply some wood on it for better look.
  
 Probably it will be finished in the start of new month


----------



## Wisor

I got the tubes today. New ECC82 tubes from JJ cost me 7€ each + 22% tax plus "around 7€" for two belden sockets.
 I still need a power and two headphone jacks and some "minor" material.
  
  
 I have a question for you guys. Elements on C2,C4 (marked C10/C11) and C3a/C5a should be *.22uF, 63V​*  
I was looking elements on mouser.com and I don't know which ones to buy.​  
Is audio quality depending on those four elemens. Because prices are from 0.2€ up to 2€.​  
Which ones would you recommend?​


----------



## brokentofu

Boards arrived, thank you Howard.
  
 Is there a way to add a switched resistor in series with the pot? Something that would be like a gain switch. I'd like to be able to drive ~60‎Ω headphones normally and if I ever upgrade to something in the 250‎Ω-300‎Ω range I'd like to bypass the extra resistor. What value of pot and switched series resistor should I select?


----------



## brokentofu

Started populating the board
 http://i.imgur.com/YcehsFA.jpg


----------



## Shensmobile

Is there any way for me to get two of these boards?  If there's none of these left, is there a 12au7 Starving Student schematic available that I can use to make my own?
  
 Edit:  Nevermind, I found the schematic   Hopefully there are still some boards left, but can anyone confirm that this schematic is the one this PCB uses?  
 http://www.diyforums.org/SSMH/variants/SSMH-12AU7.gif
  
 I'd like to order some parts and get this build started!  Thanks everyone!


----------



## fuens

shensmobile said:


> Is there any way for me to get two of these boards?  If there's none of these left, is there a 12au7 Starving Student schematic available that I can use to make my own?
> 
> Edit:  Nevermind, I found the schematic   Hopefully there are still some boards left, but can anyone confirm that this schematic is the one this PCB uses?
> http://www.diyforums.org/SSMH/variants/SSMH-12AU7.gif
> ...


 
 Hello mate.
 Yes, this PCB uses this schematic.
 Have fun and enjoy it!
  
 Toni


----------



## Shensmobile

Thanks!  I've already started ordering parts and an enclosure.  Hopefully Fred gets back to me soon about picking up this PCB 

 Has anyone built this circuit on a perf-board?  I might "test assemble" everything on a perf board to see how it sounds.  Does anyone have any tips to avoid cross talk between channels when building on perf board?


----------



## brokentofu

Amp works great. One of my tubes glows less bright than the other. What would cause that? Is it even a potential problem?


----------



## brokentofu

I put it into a temporary enclosure. I think I need to change the pot out. It is a tad noisy when I adjust the volume. I think I will try and alpha brand one next. http://i.imgur.com/2JAq0lY.jpg


----------



## Wisor

Hey guys,
  
 I am still waiting for two 1/4 neutrik jacks and four other capacitators. Hopefully I will get them soon.


----------



## Fred_fred2004

Sorry I've not been much help with these recently, life has dealt a few blows 
  
 I have plenty of the boards still so if anyone needs one just drop me a pm
  
 cheers
 FRED


----------



## Wisor

My amp is almost done.
  
 I am still waiting for custom case I ordered, hope It will be done soon 
  
 Will upload some pics, when it will be done.


----------



## Phetu

Would this http://www.mouser.com/ds/2/260/irm-60-spec-540962.pdf be any good powering this amp?


----------



## Wisor

I bought this one:
  
 http://www.ebay.com/itm/221770469278?_trksid=p2057872.m2749.l2649&ssPageName=STRK%3AMEBIDX%3AIT


----------



## Nathan P

Hey Fred, sent you a PM. Hope you're still around!


----------



## Nathan P

Do you need a special tool to install the connector for the terminal blocks to the wires? Obviously on the pcb side they just solder on.

The screw type look like they'd be a tight fit.


----------



## Nathan P

Another Fred Starving Student joins the fray!
  



  
 Initially had one of my caps polarity messed up but switched that around and it's working great. Aside from the fact that I wired my L/R backwards on the input side.
  
 I'll fix that and I think I may swap out the 50k resistor prior to the pot to a 100k... I'm getting some channel imbalance and methinks using more of the volume will ameliorate that somewhat. Then it's time to get my case finished. 
  
 So far I'm not super super loving the sound of the GE tubes I grabbed. It's sounding just a bit thin in instrumentals. Vocals are cutting through like crazy though. Even without a case background noise is negligible so I have high hopes for a practically zero noise floor once buttoned up.
  
 -Nathan


----------



## Nathan P

BOM for my build is here:
  
 https://www.mouser.com/ProjectManager/ProjectDetail.aspx?State=EDIT&ProjectGUID=ED556D7D-F5AA-4079-B0F2-385EB79A7395


----------



## Nathan P

Notes from further experimentation:
  
 Wima MKP10's will NOT fit on this board. I thought I could bend the leads and make it happen, but they bump into other things (Tube sockets for C2 and C4, output connections for C5a and C3a) The holes are pitched for 7.5mm spaced caps. I'm uing 5mm spaced Wima MKP2's with the leads tweaked. It's a snug fit if you want to use molex connectors for the output, but they fit. So far I'm perfectly happy with their sound. When I have a reason to order more stuff from Mouser, I may pick up some Vishay MKT1822 caps to try out in those positions and check the fitment. They're the only other cap I'm really interested in trying.
  
 The Nichicon Muse ES 16v 220uf caps fit C7 and C8, barely. I had to tweak the leads just a tiny bit to make sure the barrel of the cap wasn't touching the lead on the resistors next to the caps. Likely if I had gone with a resistor with a slightly smaller body than the Vishay metal films there would be a bit more spacing. But I like these resistors and I made it work. 
  
 The spacing on the mosfet connections works for the 2.54 mm pitch molex connectors. I don't like soldering wires directly to PCBs so I redid those as well as the input/output connections.
  
 Cheers
 Nathan


----------



## twst

Boards arrived just fine, cheers fred.


----------



## fuens

Here another amp
 Thanks Fred!!!! :-D


----------



## DaKube

My two boards arrived today. BIG thumbs up to Fred for doing this. I imagine it's a lot of hassle for a couple bucks. Very high quality boards for such a great price.

 Couple of questions for the group.
  
 1) On that Mouser BOM that's been linked a few times, I don't see it including the Molex or other connectors. Are people just soldering to the board? That's OK by me. Screw type are OK, too. (I saw the parts listed in the thread)
  
 2) I also have a Mac Mini case, but mine is metal and hard plastic. The top, which will house the tubes and the heat sinks, is mostly plastic with a thin sheet of metal below. Is that a terrible idea? Other option is to house heat sinks behind the board, still in the case. It's metal on the bottom. Or, just buy a case and use that one for another Class D project, with far less heat.
  
 Thanks again, Fred!


----------



## snafu1

Fred,
 I received your boards a couple of weeks ago. Today -  I just finished it 
	

	
	
		
		

		
			




 Powered it up for the first time and no smoke - always a good sign!
 It worked just fine. The sound is pretty darn good too.
  
 To answer DaKubes's questions (above) - I ordered the standard Molex header (2.54mm or 0.1" spacing). They worked fine, except I had to slightly enlarge some of the holes on the PCB with a drill bit. Of course you then also need to order the pins for the cable connector. I found a "cheap" crimping tool on Amazon for $20 (search for HT-225D Full Cycle Ratchet)
  
 Also, I think you'll have a problem with the plastic top. I found the tubes get up to 140 degrees F and the heat sinks for the MOSFETS get up to 125 degrees. You are going to want a metal case.


----------



## elecen010

Are these still available?


----------



## Wiljen

elecen010 said:


> Are these still available?


 
  
  
 I pm'd Fred several days ago and haven't heard anything back. I suspect they may still be available but Fred is not.    Hope it is just a vacation or a business trip and nothing less pleasant.


----------



## snafu1

wiljen said:


> I pm'd Fred several days ago and haven't heard anything back. I suspect they may still be available but Fred is not.    Hope it is just a vacation or a business trip and nothing less pleasant.


 
 I received 2 boards from him just a month ago. So, they should still be available.
 I had PM'd him and he got back to me after about a week.


----------



## Wiljen

I have a couple LED power supplies that are capable of 48V 2.5A per channel with 3 channels per unit that I was going to use for building an amp.  I have been thinking about building one of the SSMH or one of the GainClone designs.    This is usually when I start thinking stupid stuff like what would happen if you used the Tube stage from the SSMH as the pre-amp for the power stage of the Gainclone and combine the two?    Is this impossible, stupid, or something that might be an interesting thought?


----------



## NelsonHolland

I ordered four pcb's on March 20th and received them today in excellent condition. (From Australia to Holland in less than two weeks)
 A big thanks to Fred for his speed and effort!


----------



## brokentofu

I've discovered a channel imbalance, the right side sounds a bit more full than the left side. Ive also noticed the tube on the left glows a tad dimmer. Would those two things be related? I've got access to multi meter and oscilloscope. How should I troubleshoot this?


----------



## snafu1

brokentofu said:


> I've discovered a channel imbalance, the right side sounds a bit more full than the left side. Ive also noticed the tube on the left glows a tad dimmer. Would those two things be related? I've got access to multi meter and oscilloscope. How should I troubleshoot this?


 
 You know, now that you mention it. Mine is kind of the same. I only notice it when I have the volume low. Seems okay at normal listening levels. But maybe I'm fooling myself. I'm guessing here, but I assume this was caused by the fact I didn't pay the extra money to buy matched tubes. I'm assuming one tube has slightly more gain than the other.
  
 **Edit**
 Hmm, I exchanged the positions of the tubes and the right channel is still slightly fuller at low volumes. So much for the tube theory. Maybe the volume pot isn't balanced. It has 2 separate windings for left and right and could theoretically cause this. That would also explain why the issue seems to go away at louder volumes.


----------



## Phetu

My starving, sounds good with my Hifiman HE-400 =).
  
 https://flic.kr/p/HhoHbz


----------



## brokentofu

phetu said:


> My starving, sounds good with my Hifiman HE-400 =).
> 
> https://flic.kr/p/HhoHbz



what box is that and what plug is that?


----------



## Phetu

Box is Hammond 1444-8 / 152x102x51mm and Neutrik something, locking 6.3mm stereo


----------



## UnknownAX

I'd like to finally build a tube amp to see what it's like and I've got a few general questions about the PCBs and the amp. It'd be *truly appreciated* if someone could help me out. Until now I've stuck firmly to SS amps.
  
 About the PCB:
  
 - The dimensions of the board are 76mm x 76mm, is this correct?
 - What spacing do the potentiometer holes on the PCB have? Would this pot fit the holes on the board? http://www.taydaelectronics.com/potentiometer-variable-resistors/rotary-potentiometer/logarithmic/50k-ohm-logarithmic-dual-taper-potentiometer.html
  
 About the amp and tubes in general:
  
 - How much power do the FETs dissipate? Do I really need a proper heatsink or would a strudy aluminium enclosure be enough?
 - What should I pay attention to when looking for tubes? I could get 5814A Philips tubes or ECC82 Valvo, RFT and JJ tubes, are all of these just fine and drop in replacements?


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## Andy Mac

Hi all,
I am wanting to build this nice little amp and I was wondering if the PCB is still available?
If not, is the drawing for it available so I can etch my own?
I have made PCB's before, just need the drawing...
Thanks in advance.

ANDY in NZ


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## Fred_fred2004

No problem with the boards, flick me your email and number you want
 cheers
 FRED


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## kendamalee

Fred,
  
 If the boards are still available could I still get one?

 Thanks,
 Eric


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## Fred_fred2004

Hi
 send me your email address plus the number you want and I'll send a Paypal invoice
  
  
 cheers
 FRED


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## fast14riot

Well, good to see this thread still here! I bought a board a couple years ago and got distracted with other things and forgot about it. Found the board the other day and would like to get it built, will be going back and looking for a current BOM as well as reviewing build sheets. Reading through this, i cant believe how much i have forgotton, but other interests have taken over.

Even if i dont fully understand the thoery and how it works, i can follow directions and build most anything, lol! 

Just dont beat me up too bad as im digging through here again looking to make some sense of it all...

Next up are new head phones.


-Alexander


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## Greg96

Fred, are there more ssmh pcb's available? Let me know, thanks!


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## Fred_fred2004

Hi Yes got plenty    (for now)

 Boards are $3.75US each 

 postage in Australia is $2.50

 worldwide airmail $4.00US for up to 2 boards, then it jumps to $10.00US for up to 250g

 send me your email address plus the number you want and I'll send a Paypal invoice
  
  
 cheers
 FRED


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## DudeMyCans

Hi Fred, is the board for the original Pete Millett 19J6 version or the later one ?

I have one I built up a couple of years ago with 19J6s, on perfboard, but I'm thinking of rebuilding it onto a PCB. I've probably even got enough parts left over to build another one as well .


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## jekjek

Hi Fred,

Can the board support e80cc, e182cc and 12sn7(via adaptor)

Cheers,
Emil


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## DudeMyCans

dudemycans said:


> Hi Fred, is the board for the original Pete Millett 19J6 version or the later one ?
> 
> I have one I built up a couple of years ago with 19J6s, on perfboard, but I'm thinking of rebuilding it onto a PCB. I've probably even got enough parts left over to build another one as well .


 
  
 I've just done what I should have done before posting my question and read the first post in the thread. I now realise that it's not for the 19J6's.
  
 Never mind.


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## ThermalAlchemy

Thank you, I received your boards for the SSMH, they came in a reasonable time thank you again. I did find out your board did not fit in the recommended case build of materials for the SSMH. The build of materials parts list from Mouser or DigaKey I found the resistors are too big to fit on the board, the body of the resistor actually larger than the were the holes are drilled, unless you mount them at a 45 degree angle.  " look at the size of R13 in the photo, that Panasonic 2W resistor will never fit in the tiny space. The Alps pot pin will not fit,
  
 the WIMAs caps will not fit. The nichicon 680uF cap overlaps the R6 resistor. Can you please provide the part numbers and name of supplier for the super small resistors and smaller caps it would make it easier for the first timers who are trying to follow the build of materials on the diyforms.org
        I built the SSMH 19J6 version on a purf board next to your board in the photo. Believe me, that was not easy for a first timer.( There was a lot of learning curve going on when I was building that on purf board. I could not find a SSMH 19J6 PBC board


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## Fred_fred2004

You need to read this thread, this board is nothing like the original BOM and so would not fit those parts, there is a BOM for this board up near the beginning


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## ThermalAlchemy

thank you for the quick reply. I will go over this thread more thoroughly. Thank you for throwing in one extra board in my order. Once I build one for myself, I will build and gift the others to friends.


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## fuens

Here goes another one! 
	

	
	
		
		

		
			




  
 Thanks to Pete Millet, Dsavitsk & specialy to Fred_fred 

 Also all Head-fi'ers (with his comments) who make it possible.
  
 Enjoy your projects!


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## rmhuntley

how much do these PCBs run?  I"m looking at grabbing one


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## Fred_fred2004

Boards are $3.75US each 

 postage in Australia is $2.50

 worldwide airmail $4.00US for up to 2 boards, then it jumps to $10.00US for up to 250g

 send me your email address plus the number you want and I'll send a Paypal invoice
  
  
 cheers
 FRED


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## Andy Mac

I have finally gotten round to building my amp (can't move due to being thrown off my dirt bike..)
I am wondering if anyone has fitted a couple of VU meters to each channel?
I like the look of them working and they would suit the theme of the amp I'm building..
Problem is I don't know where to start with these.
I'm picking there is some sort of calculation in choosing the right ones a long with actually wiring them up....
Do these distort the sound output of the amp?

Any help appreciated.

Andy in NZ


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## Andy Mac

Got it all hooked up on the workbench, powered it up, no smoke or sparks so that was a bonus.
I plugged in some cheap earhones, hooked up my Fiio X3 and voila!! Tube magic!!!
The tubes glow a nice even healthy orange and the mosfets heat up very well.
When nothing is playing or the music is quiet, there is a loud hum... very annoying!!
It increases with volume control and is the same on both channels. It is also present with no source being plugged in...
I have wired my tube holders on wires and not directly to the board, will this effect it?
I notice if I touch the tubes or the volume pot the hum changes...

Any ideas or pointers?

It's going into a wooden case once this issue is sorted...


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## muskyhuntr

Hard to tell without pictures and other info, but sounds like a grounding problem.  From your description, one possible cause is that the pot case is not grounded.  
Check that input wiring is away from AC.  Twist input wiring.

Me


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## Andy Mac (Jun 18, 2017)

Thanks for the help. I'll report back once done.
Another thing, due to the case design, I am not soldering the tube sockets directly to the pcb.
Is this an issue?
Is it preferable to bunch all 9 socket wires together, spread them out or twist certain ones together?
I just want to eliminate any potential noise....

I have also lined the entire inside with aluminium adhesive foil. I will ground this to the pcb as well... is this a good idea too???


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## Andy Mac (Jun 27, 2017)

Done. Sounds awesome. I'm more than happy for a first build.


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## chitnik

I joined this forum so that I could order a couple PCBs. And they are already on the way! Thank you fred_fred2004!


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## chitnik

I started building my BOM based on a BOM another member posted in this thread. After building the list, I noticed the other member used 1/8 watt resistors. Of course, the schematic calls for 1/4 watt resistors. Should I update my BOM to use 1/4 watt resistors? Or will the 1/8 watt resistors be okay?


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## chitnik

Never mind. I figured it out. They are "military spec" which means they are equivalent to 1/4 watt consumer spec.


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## Detectit

Are these pcb 's still for sale? Ordered the parts. And it's convenient to have a board. 

Looked on the ebay shop. But could not find anywhere.


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## jeeper

Hi, I have a question. I have accidentally ordered 4 non polarized capacitors with the specified values as written in the OP for:
c2 c4 c3a c5a

Would these be okay to use? or do they have to be polarized? Thanks.


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## DaKube

Hi Fred,
Do you happen to have the artwork for the board? I want to have Mammoth custom drill a case for me and having the exact location of the tubes will help with that. I could measure, but you guess that a guy who can't even drill his own case also really sucks at measuring, too. Thanks!


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## Etlie (Nov 29, 2017)

Hi all

This is my first time doing anything like this and will be a very silly question for most of you. I've wired everything up, and the amp works however one tube is considerably brighter than the other. One lights up like a light bulb and the other is very dim. Ive switched both tube around and its the same side which has the problem meaning both tubes are fine. I also checked the mosfet, and the mosfet on the same side as the dim tube is significantly warmer than the other mosfet which is cooler to the touch. Is this normal? Have I wired up something wrong?


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## Nathan P (Jan 13, 2018)

Finished V0.1 (This enclosure is a trial run for one I'll build from scratch out of hardwood. The metal switchplates are quite rough as well as I'm working only with hand tools at the moment.) of my Starving Student using one of Fred's PCBs today. I finished the actual amp circuit over a year ago but life got in the way. Finally got a chance to finish it. The box was supposed to be a pet funerary urn. 

Took some troubleshooting with grounding and isolating signal connectors to get the noise floor down, but it's dead silent now and sounds amazing with the GE tubes I picked up.
















Thanks for the awesome PCBs Fred! You rock.


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## Detectit

Nice Nathan. 

Mine finished two weeks ago. Didn't take the effort to make a case myself.

I have made a 3.5 mm male jack in the case. Where I can pug in the Cayin N3 directly.

Some orange led's in the tube sockets which I can turn off. 



 

 Nice little project.


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## Nathan P

Nicely done!

I have a second PCB, I'll probably leave this one as is, maybe clean up the cosmetics a bit. v2.0 I'll probably make a case from scratch if I can get access to the tools I need.

My main source is an Audient recording interface (nice Burr Brown dacs) so I went with RCAs. I have a nice 3.5mm to RCA cable that I use with a dragonfly black when I'm listening from my laptop.


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## spencerb

Thanks for the boards, going to start my build soon!


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## Andzmz

Hi, 

I'm wanting to build the SSMH over the summer for a beginner project.
Is there any way I can still get these boards? I'd only like a single one please!


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## ThermalAlchemy (Mar 2, 2018)

Andzmz said:


> Hi,
> 
> I'm wanting to build the SSMH over the summer for a beginner project.
> Is there any way I can still get these boards? I'd only like a single one please!


 Read back in the thread for a guy named Fred I remember about a year and a half ago I bought a simple circuit board for him it came as a little Greenish fiberglass circuit board with nothing more than screen print and holes .   I was working on remaking the circuitboard on a  Circuit design software so I can send in the Gerber files and have them remade brand new I got about 90% finished but then went through a house move and work got too busy I may tackle that project again because I too want a circuit board


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## Nathan P

I have an extra if Fred can't get one to you.


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## ThermalAlchemy

For comparison sitting on a notebook paper the red one above is a Millett Max max below is the starving student divided up into two small circuit boards


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## Fred_fred2004

ThermalAlchemy said:


> For comparison sitting on a notebook paper the red one above is a Millett Max max below is the starving student divided up into two small circuit boards



Just for clarification you have two starving student boards there


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## Fred_fred2004

The boards are still available, but we are reaching the shallow end and they will run out soon

Boards are $3.75US each 

postage in Australia is $4.00


worldwide airmail $5.00US for up to 2 boards, then it jumps to $10.00US for up to 250g


send me your email address plus the number you want and I'll send a Paypal invoice

cheers
FRED


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## ThermalAlchemy

Fred_fred2004 said:


> Just for clarification you have two starving student boards there


 Yes Fred thank you I will edit my remarks and clarify there’s two boreds sitting there I was doing that response and reply on the fly while I was driving in my car at the same time not paying much attention thank you for bringing it to my attention so I can clarify it to others and also thank you for your boards


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## Andzmz

Fred_fred2004 said:


> The boards are still available, but we are reaching the shallow end and they will run out soon
> 
> Boards are $3.75US each
> 
> ...


I PM'd you


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## Aspringv

Hi there, 
I'd be interwsed in a starving student PCB please?
I'll drop you a pm.

Thanks!


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## Shambl3r

Hi all,

So I've finished building the amp from Fred's board - however its not working!

Heaters on the tube warm up, MOSFETs get hot, but no audio comes through the headphones when plugged in, and nothing I can see makes any difference?

I've got some photos of both sides, though I've un-plugged some of the connectors to make it a bit easier to see whats going on.

https://imgur.com/a/7IvDUv3





Does anyone have an idea what I could try to work out where I've gone wrong?

I used the BOM from here: https://au.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=def7402dc6

And fred's BOM as well for assembly. I think I've got different values on the resistors coming off the input, but that's what was in the mouser BOM, so I installed it

Would really appreciate some help! 

Thanks,
Sam


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## Nathan P

First thing that comes to mind to me is to make sure that your mosfets are wired correctly.


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## Pete Basel

Nice work, maybe someday I'll build one!


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## kickngas

So, who has an extra board they are willing to sell?  I have not gotten a response from Fred.


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## kickngas

Nobody has an extra one???


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## spencerb

I might, I can check this weekend.


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## Nathan P

I've got one. Shoot me a PM.


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## ThermalAlchemy

kickngas said:


> Nobody has an extra one???


 Would you like a photocopy or detailed picture with measurements so you can overlay on a Perf  bored  and do some point the point and just lay down your own traces or wire .  I have a set I have not populated the board yet sitting on my shelf.  Unless you must have a board I know it is much easier and convenient .  My first attempt at a Purf board but without a template just by Eye was pretty messy .  But it was a good learning experience .


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## kickngas (Nov 9, 2018)

Thanks guys!  I really like using a board for aesthetics. PM sent


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## ThermalAlchemy

kickngas said:


> Thanks guys!  I really like using a board for aesthetics. PM sent


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## kickngas

Thermal, thanks for the pics!  I have one on the way from Nathan.  I may try a perf board version just for kicks.


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## Nathan P

BOM is here:
https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=d7adb25dd2

I did a little writeup for Reddit that you might find useful. There's a copy quoted here:
https://www.head-fi.org/threads/millett-starving-student-hybrid-amp.319231/page-469#post-12448808

Pics of my build here  :
https://imgur.com/a/7IWB9

I'll drop it off at the post office today, it'll go out in the morning. Tracking here:

https://tools.usps.com/go/TrackConfirmAction_input?qtc_tLabels1=9400109699938948388584


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## kickngas

Got the tracking info, and the links are a great help! Time to start ordering parts, thanks!!!


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## Nestade

Hi 

Anyone selling a SSMH PCB with shipping to Germany (PayPal) or are does anyone have the Eagle-Files so I could etch the PCB on my own?
Thanks in advance!

Best regards,
Nestade


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## jlav10

Does anyone have any more of these left? I live in the USA. Thanks!


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## jlav10

Nathan P said:


> BOM is here:
> https://www.mouser.com/ProjectManager/ProjectDetail.aspx?AccessID=d7adb25dd2
> 
> I did a little writeup for Reddit that you might find useful. There's a copy quoted here:
> ...



I was looking at your BOM, and for C3a and C5a, you used film capacitors. However, on the schematics for the 12au7 version, it says to use electrolytic capacitors. Was this a mistake or was it intentional? Thanks!


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## Nathan P

Definitely intentional, but are you sure about that? C3a/C5a are bypasses for C3/C5 which are electrolytics. I'dI be strange to bypass an electrolytic with another electrolytic. Also, 0.22uF is a smaller value than most modern electrolytics come in.

In general I don't use electrolytics with values lower than 2.2uF or so. Films are superior in every aspect.


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## Nathan P

Looking at Fred's pics in post #1, C3a/C5a are definitely films in his build.


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## jlav10

Nathan P said:


> Looking at Fred's pics in post #1, C3a/C5a are definitely films in his build.



I could be wrong, but on the schematics from diyforums.org, it looks like a electrolytic capacitor. If it was meant to be a electrolytic capacitor, is there any harm in replacing it with a film one? Thanks again

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


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## Nathan P

Zero harm. Electrolytics are inferior in every respect except for capacitance per unit volume.

Looking at that schematic, I think the creator just got "lazy" with the symbols. The symbol used doesn't really mean electrolytic it's just a polarized cap symbol. If using an unpolarized film cap you just ignore the polarity. The intent is clearly for it to be a film bypass.


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## jlav10

Nathan P said:


> Zero harm. Electrolytics are inferior in every respect except for capacitance per unit volume.
> 
> Looking at that schematic, I think the creator just got "lazy" with the symbols. The symbol used doesn't really mean electrolytic it's just a polarized cap symbol. If using an unpolarized film cap you just ignore the polarity. The intent is clearly for it to be a film bypass.


Thanks!


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## ThermalAlchemy

They are Wilma film caps


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## tomb

This lazy schematic drafter says the film caps don't belong to Fred Flintstone's wife.  They're WIMA film caps, not Wilma's.


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## Nathan P (Dec 20, 2018)

Note that the films in my BOM are mkp2 as there's not room for the mkp10 on Fred's boards. I believe Tomb's boards use the mkp10 which is probably a better cap. I'd argue that in this application the difference is going to be small though. 

If stock of the WIMAs is ever out, Kemet PHE426 are a nice series as well, and for a polypropylene film they tend to be on the smaller side physically.


----------



## DrivenKeys

Hi everybody! My amp has been sitting incomplete in a box, and I finally got it together

 
I swear, I didn't originally intend for the robot face, but couldn't be happier it happened.

Overall, it sounds amazing, but I need to tweak volume control. When driving my 250 ohm Beyers, I have to provide an overpowered source. After combing through whatever I could find on this and the Starving Student thread, I think it's because I combined a 100k pot with 47k resistors at the source.

I'm great at following directions, slow on theory, so perhaps someone here can help me out before I dig in again: The pot is an Alps blue, I splurged after I damaged my cheap Alpha. So, I've got an awesome pot, can I simply remove the resistors before it? 

It's said the resistors attenuate the signal so it stays in the upper range of the Alpha pot, as its lower range is unreliable. The goal being comfortable listening around 12 o'clock. Since this Alps is reliable down to zero, that shouldn't be needed, right? 

My first guess is to just remove the resistors. Will this have the desired effect of raising volume without negatives? Do I just need a lower impedance pot?


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## tomb (Jul 24, 2019)

amazing ...​


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## fuens (May 17, 2020)

@DrivenKeys

Hello mate.
I recommend as drawings said R16 and R17 50k (47k resistor) and pot 50KAx2 dual 50K Log.

I builded three and are exellents.
Move perfectlly my beyers 250ohm and Hifiman HE-500
The only upgrade  I made was increasse to 1000uF C3 and C5 (nichicon muse fg 1000uf 63v) but with the original design of 470uF is enough.
Enjoy


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## Darkblade48

Just wondering if anyone still had these PCBs kicking around (or if Fred has a couple left?)


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## IKillPCParts

Got the same question as Darkblade, do PCBs for this still exist? Or hell, even a GERBER file if paid for?


----------



## Darkblade48

Eh, worst case scenario is that I design the PCB myself. Was just trying to save a bit of work.

I can try my hand at PCB design and then post up the schematics for anyone that's interested; only problem is I haven't done PCB design work for about 15 years now, so I'm a bit rusty and will need someone to double check my work


----------



## jekjek

I still have 1 pcb


----------



## Darkblade48

jekjek said:


> I still have 1 pcb


I'd be interested in it, if postage and all isn't too bad. Shoot me a PM!


----------



## Shakydog

Hi Fred_Fred2004

As others, are these boards still on sale? Anyone done a design yet?


----------



## IKillPCParts (Jun 29, 2020)

Shakydog said:


> Hi Fred_Fred2004
> 
> As others, are these boards still on sale? Anyone done a design yet?


I've made a PCB using the schematic made for using 12AU7 tubes, I've already ordered it with oshpark so I hope it's fine already. I'm expecting a lot of criticisms though  and already I've spotted a mistake! Just left in a GND-GND trace on the board, it's fine but it's going to bug me forever.


Spoiler














EDIT: Forgot to add that my schematic basically just takes Dsavitsk's schematic and doesn't do much other than "cleaning it up" I guess, in my eyes.


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## Darkblade48 (Sep 11, 2020)

Shakydog said:


> Hi Fred_Fred2004
> 
> As others, are these boards still on sale? Anyone done a design yet?


I have re-traced the schematic and am working on PCB design, but with slightly different components (such as using WIMA MKP series film caps). However, I am running into some trouble with connecting up all the nets in the PCB design!


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## Darkblade48

I am pleased to report that the PCB I designed following Dsavitsk's updated schematic for using 12AU7 is functional. Please try to ignore the mess of wires  

Now to find an enclosure!


----------



## skajohyros

Darkblade48 said:


> I am pleased to report that the PCB I designed following Dsavitsk's updated schematic for using 12AU7 is functional. Please try to ignore the mess of wires
> 
> Now to find an enclosure!


Nice work.


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## bigalila

I'm in the market for a couple boards if anyone is still producing them or has has some to sell.  I had one running for a good 6 years or so and it took a poop on me.  IRF 510 burned up and took some other components with it, including a tube.  Now i'm looking for a board to build a new one.


----------

