# Best DIY tube amp kit for under $100?



## Danthrax

I wanted to try making a tube amp, nothing too complicated or too expensive. I'd prefer being able to just use a kit for the ease of finding parts but if anyone has a list of parts for an amp and where said parts can be purchased from that would be great too. I'm really new to this so any help would be great.


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## 00940

Search for "starving student". Tons of info to be found around here.
   
  Here's the website of the designer: http://www.pmillett.com/starving.htm
  And this website sells most of the needed parts: http://beezar.com/oscommerce2/catalog/index.php
   
  It's hard to beat in that price category. Under 100$ and asking for a kit, you're pretty much restricted to hybrid amps... unless you're a good scavenger. Then a simple amp like the kaidan could possibly do the trick: http://www.wavebourn.com/forum/viewtopic.php?t=998


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## nikongod

"safe against tube rollers" 
   
  I see he reads head-fi. Any octal tube, any octal socket.


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## Fred_fred2004

Have a look at
   
http://cgi.ebay.com.au/6DJ8-Tube-Single-End-Headphone-Amplifier-Bare-PCB-/110492488358?pt=Vintage_Electronics_R2&hash=item19b9dd92a6
   
  its very simple and easy to build and runs off 24 volts
   
  cheers
  FRED


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## 00940

15VPP output from a 6DJ8 fed with 24V ? That's gonna be sweet distortion.


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## Fred_fred2004

Take the specs with a grain of salt, it sounds very good for the $$$$$$$$$
   
  cheers
  FRED


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## Danthrax

I think the starving student would work great. One more question though what kind of DAC would I need? I would be hooking this up to my PC and I already have a Xonar DX and I don't think it has a line out but I'm not sure. Would it be possible to incorporate a grubDAC into the same box as the amp? And if so is the kit from beezar the cheapest way to get the parts for one or can I get better for the money?


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## nikongod

Multiple components in 1 box is a bad idea. 
   
  You *could* put a DAC in the same box as the MHSS or any amp for that matter, but what happens when (not if) you want to upgrade one? What happens when you want to use your familiar DAC to run your newly built amp in another chassis? How about when the amp wears out its welcome, but you still like the DAC? or the opposite..
   
  It costs slightly more, but put the DAC in its own box and the amp in its own box. When it comes time to sell one thing, sell one thing.


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## Nemo de Monet

Quote: 





00940 said:


> 15VPP output from a 6DJ8 fed with 24V ? That's gonna be sweet distortion.


 

 Like was noted above, take the specs with a grain of salt. It also runs (quite) happily from higher voltages; a lot of people built 'em with 32V or even slightly higher PSUs. (I have, um, four of these amps, or variations thereof.)
   
  There's a really, really long thread about those boards around here somewhere.


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## Danthrax

My next question is can any of these drive 600 ohm AKGs? I would assume the millet can.


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## 00940

The starving student outputs up to 7Vrms. Assuming you have the K240m, you'd get up to 107db or so. The Kaidan should do about the same. The ebay amp way less.
   
  Edit: I completly forgot that the tubes for the starving student are now hard to find and quite expensive. You can replace them by common 12au7, as shown here: http://www.diyforums.org/SSMH/SSMHvariants.php
  I'd expect the voltage swing to be a bit lower than the original though.


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## Danthrax

I'm almost done buying the parts but I can't find any reasonably priced tubes. Does anyone know of a place?


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## 00940

http://cgi.ebay.com/2-Vintage-Sylvania-12AU7-Tubes-Test-NOS-/250774809879?pt=Vintage_Electronics_R2&hash=item3a6357ed17
   
  Plenty of those on ebay. Just an example from what "seems" a reliable seller (in other words, no personnal experience with him).


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## Danthrax

Um, I need the 19j6 tubes for the starving student from the site?


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## 00940

See post #11. The change from 19V heaters to 12.6V heaters means that you will drop more voltage over the mosfet, so you need a tad bigger heatsink.
   
  You have some 19J6 on ebay but they're like 20$ each. There's also tubedepot at 15$ each  but you'll have to check for actual availability: http://www.tubedepot.com/nos-19j6.html


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## Danthrax

Yeah I just read that so what exactly will I need different from this parts list for this to work? http://www.pmillett.com/file_downloads/starving_bom.pdf
   
  Sorry I'm not exactly a master of circuitry so a new schematic and parts list would be great.


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## holland

There's a starving student build thread.  Your questions are answered in there.


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## nikongod

And in the schematic linked to on the previous page. 
   
  Reading through these things slowly and painfully is a great way to learn about them.


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## Danthrax

I just got 2 from ebay they were like $30 shipped.


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## Danthrax

So one more question can I output via my Asus Xonar dx to a 1/4 inch jack on the amp or would that be bad? Basically do I need a dac  with right and left out or will the headphone out be ok? How would this effect the sound if at all?


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## 00940

Just take the signal from the mini jack on your sonar dx which is marqued "front". The choice of connector on your amp is yours, just get the adequate cable (mini to rca if you install rca, mini to mini if you install a mini jack).
   
  A headphones output obviously has left and right signal, hasn't it ?


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## Danthrax

Quote: 





00940 said:


> Just take the signal from the mini jack on your sonar dx which is marqued "front". The choice of connector on your amp is yours, just get the adequate cable (mini to rca if you install rca, mini to mini if you install a mini jack).
> 
> A headphones output obviously has left and right signal, hasn't it ?


 


  Yeah but I thought I read somewhere that it's bad to double amp or something?  That makes sense though since I've seen zunes go to amps before, I guess I was looking at the wrong thing...


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## holland

Quote: 





danthrax said:


> Yeah but I thought I read somewhere that it's bad to double amp or something?  That makes sense though since I've seen zunes go to amps before, I guess I was looking at the wrong thing...


 
   
  It's not ideal because a headphone amp doesn't really need a preamp, but then again a DAC amplifies to line level, which is then attenuated by the amp's volume control.
   
  One tip, for the SSMH, get a good pot.  The BOM pot is horrible, and the gain is rather high, and the pot tracking will be of large importance.  I have to rebuild mine someday, but right now it is just gathering dust.
   
  As for needing a DAC, no you don't need one.  You may want one sooner than later, but that's different than needing it.


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## nikongod

Quote: 





holland said:


> One tip, for the SSMH, get a good pot.  The BOM pot is horrible, and the gain is rather high, and the pot tracking will be of large importance.  I have to rebuild mine someday, but right now it is just gathering dust.


 

 Shunt it.
   
  Poosticks. My best link is dead
   
  Its basically what is shown in figure 2 except that the LDR is replaced with a conventional pot wired from the wiper to one end, with the other end floating.
kind of sort of explains it with a little imagineering


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## Danthrax

What is a pot?


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## holland

Quote: 





nikongod said:


> Shunt it.
> 
> Poosticks. My best link is dead
> 
> ...


 

 I did shunt it, and it still sucks....it's the worst pot ever and has been permanently crossed off my list of pots to use!  I had to add an input resistor too.  I probably should have shunted with a larger ratio, but I wanted to use my 600-ohm headphones along with my 32-ohm things.  An input resistor on a switch helped there.  The stock pot tracks *really* bad before 9 o'clock, really bad.
   
  YMMV.
   
  @ Danthrax, A pot is potentiometer, your volume control.


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## Danthrax

Ok well I have decided to go with the 12au7 version and I used the parts that monkeyevil listed n this post http://www.head-fi.org/forum/thread/319231/millett-starving-student-hybrid-amp/5640#post_7253142 am I missing anything else? (I ordered the tubes and the sockets already) And if that pot isn't good what is a good one?


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