# DIY portable tube headphone amp?



## Nixon

Just finished building the Raytheon JAN6418 tube amp kit and fell in love with the tube-y sound. Would just shrink this amp down to make it portable, but the tubes ring like a bell if you knock it. 

 Does anyone know if there's a scematic for a amp based around something like a 6111, such as the ALO Audio "The Continental" or a Go-Vibe Porta-tube?


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## tomb

Don't know, but I was hoping that at some point, Pete Millett would share his portable Millett Hybrid design with us at some point.  Last time I checked, it was no longer on the market, but I could be wrong about that.  It was most definitely a FOTM for quite some time a couple of years ago.


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## Nixon

If he did that, the 6111's would become extinct as fast as the 19J6's did when he published the schematic for the starving student


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## Nixon

Might buy a Muse portable tube amp and mod the heck out of it. Worst case it's only £60 wasted, and even then I should be able to salvage some parts out of it and a nice case.

http://www.head-fi.org/t/567872/muse-portable-tube-amplifier/15#post_7742310


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## bengoshi2000

nixon said:


> Just finished building the Raytheon JAN6418 tube amp kit and fell in love with the tube-y sound. Would just shrink this amp down to make it portable, but the tubes ring like a bell if you knock it.
> 
> Does anyone know if there's a scematic for a amp based around something like a 6111, such as the ALO Audio "The Continental" or a Go-Vibe Porta-tube?




I've spent a week or so researching the same question and I haven't found anything that beats the Oatley kit in the coveted "affordability & size" categories. I'm giving serious thought to taking the schematic and trying to work a p2p build on a strip board or perfboard. The Oatley PCB seems to have alot of open space. I'm thinking that a closer/tighter layout might get it small enough to make it portable. 

That would be considerably cheaper than the Chinese made Muse (which may be of questionable build/component quality).

Would a perfboard Oatley be Cmoy small? Nope, but I think I can get closer...


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## Nixon

http://www.head-fi.org/t/453425/tube-headphone-amp-kit-for-25/135#post_6565173

You can get it small enough for a portable amp. Might have issues with microphonics with the tubes unless you damp them really well.


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## bengoshi2000

Agreed.  I've got some ideas on "heavy duty damping" that I think will work.  I think that part of the microphonics problem may be coming from the PCB to the tube via the tube wires.  I'm considering some sort of workaround...  I'm also considering photo/camera batteries that would take up less space.


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## nikongod

You should look up siljosae's (spell check, I cant spell) older work. 
  He had a few neat layouts for smallish tube amps.


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## nikongod

I think I may have spelled it right! 
  Found his gallery:
http://www.headphoneamp.co.kr/ftp/sijosae/Gallery/
   
  Nope, I always add an L
  Facepalm


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## bengoshi2000

Quote: 





nikongod said:


> I think I may have spelled it right!
> Found his gallery:
> http://www.headphoneamp.co.kr/ftp/sijosae/Gallery/
> 
> ...


 

 I ran across those last week when researching... I'd give my left leg for a schematic of some of the 6111 tube based amps!!!  His 6922 designs look like they might have some heat dissipation issues...


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## Nixon

Sijosae's amps look amazing. He's posted up some circuits but none of his portable hybrid amps


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## Nixon

Found one that might interest you guys 

http://audiotronics.xanga.com/550800314/item/

 He was designing one with a 6111 too but the last post was back in 2007.

http://audiotronics.xanga.com/555817524/item/


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## Nixon

Sijosae had posted his schematic over at Headwize but the image link is dead.

http://gilmore2.chem.northwestern.edu/ubb/showpage.php?fnum=3&tid=5878
   
  Another Hybrid amp running from 12V
   
http://www.fa-schmidt.de/YAHA/index.htm and the thread over at headwize http://gilmore2.chem.northwestern.edu/ubb/showpage.php?fnum=3&tid=5637 and http://gilmore2.chem.northwestern.edu/ubb/showpage.php?fnum=3&tid=5771&fpage=1
   
  Same amp (YAHA) using a 6111
   
  http://headwize.com/ubb/showpost.php?fnum=3&tid=5771&pid=65257&fpage=25
   
  And a review of small amps
   
http://gilmore2.chem.northwestern.edu/ubb/showpage.php?fnum=3&tid=7447&fpage=1
   
  And another one
  http://headwize.com/ubb/showpost.php?fnum=3&tid=5771&pid=68791&fpage=27


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## Fred_fred2004

I've been messing about with the fa shmidt version, the aim being to get it into an altoids tin this is what I have so far
   

   
  Obviously toner transfer
   

   

   
  Notice the heatsink has changed orientation in the final version, it is just warm to the touch using 12volts so I think it will be fine in a tin
   
  I used a 12AU7 and a JRC4556
   
  sounds very nice for a simple project
   
  If anyone wants the layout to try their own just drop me a PM I use pcbartist (cos its free)
   
  cheers
  FRED


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## Nixon

Just ordered a ecc88, a 6111 and 6021 to have a mess around with. Hopefully should be able to knock together the basic YAHA with the ecc88, then shrink it down a bit with the 6111 or 6021 (depending on which sounds nicer). Might replace the LM317 with a more efficient switching regulator to decrease the power draw and hopefully increase the battery life, possible http://www.active-robots.com/anyvolt-dc-dc-converter.html . I'm assuming as the LM317 is used as a tube heater, the noise from it shouldn't be too noticeable.


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## bengoshi2000

Nixon,
  I definitely want to see pics of your project!!
   
  I broke down and bought one of the 6418 lots from eBay:  
   
http://www.ebay.com/itm/ws/eBayISAPI.dll?ViewItem&item=200736121697&ssPageName=ADME:L:OC:US:3160
   
  Yesterday I pieced together a BOM from Mouser:
   
http://home.earthlink.net/~morgan.whitney/images/K272A.pdf
   
  I'm interested in opinions on the upgrades, and I'd be grateful if y'all would double-check my components.  
   
  I decided to go with Nichicon Muse Gold for all caps.  Output caps upgraded to 1000uf and input caps to 1.0uf WIMAs (an idea from Fred_fred2004 in this thread: http://www.head-fi.org/t/522639/oatley-k272a-build).  I also added another pair of 1.0uf WIMAs to use in parallel with the output caps.  
   
  I'm a bit frustrated with the L4949 IC, it appears that no one (Mouser, DigiKey, Newark) has it in a dip-8, only in surface mount.  I know how to solder and have a good iron, but soldering smd seems to be another level of skill (that I'm not sure I've attained yet).  
   
  I'm also unsure what to do about the trim pots since I'm looking to make this a portable amp.  Can I eliminate the pots entirely and go with the stereo pot I have in the cart, or do I use the trims AND the stereo pot together?  If so, how do I wire them in?


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## Nixon

Quote: 





bengoshi2000 said:


> I'm also unsure what to do about the trim pots since I'm looking to make this a portable amp.  Can I eliminate the pots entirely and go with the stereo pot I have in the cart, or do I use the trims AND the stereo pot together?  If so, how do I wire them in?


 

 As far as I can can tell you should be able to bypass the trim pots and use a stereo pot instead. 
   
   
  As you're trying to make it as small as possible, you might want to hunt down the schematic for the first version of this amp that didn't have the 2 AA batteries and used the 9V battery for the tube heater. Battery life takes a knock but should make the amp smaller.


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## bengoshi2000

Quote: 





nixon said:


> As you're trying to make it as small as possible, you might want to hunt down the schematic for the first version of this amp that didn't have the 2 AA batteries and used the 9V battery for the tube heater. Battery life takes a knock but should make the amp smaller.


 
   
  I did take a look at that, but IIRC, it used 2 9volts in parallel... not much difference in size/weight.  :/
   
  Right now I'm thinking of going with a pair of AAAs (LR03) for the heater circuit and a 12v keyless entry battery (http://www.amazon.com/Energizer-A23-Battery-12-Volt/dp/B00004YK10) for the main.  Seems like there was some discussion in the main K272A thread that moderately higher voltages could work.  Now whether these A23 (or similar) batteries could drive the amp remains to be seen.  I imagine that battery life will take a hit.  Perhaps a pair of A23s in parallel... hmmm...


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## Nixon

Or you could use a voltage regulator to bring the 9 or 12v supply down to the 3v needed for the heaters.


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## pmillett

Welllll...
   
  I could put the design of the hybrid portable out there, as there are no plans to do anything similar.  At least for now.  However, since it uses all SMT components and a fairly complex power supply (buck regulator to get the filament voltage and a flyback to get +/-24V from a single Li+ battery), not sure it would be a practical DIY project.
   
  But at least I can offer up my experience:
   
  I tried almost every battery tube out there.  Almost all of them (well, the ones that have directly-heated filaments of less than 3V) sing like mad.  The 6418 is one of them; works great other than the singing.  BTW, if anybody needs some, I have 20 that I have no use for... send me a message, maybe $5 each?
   
  The best tube I found as far as being quiet and still having low filament power was the CK534AX, which was used in the hybrid.  I bought up all I could find, and there are very few around now.  Though you never know what might pop up out of some warehouse someday.
   
  Though a tube is certainly a novelty, maybe a single-ended JFET stage is more practical.  You can get a JFET circuit to sound and measure an awful lot like a SE tube.
   
  Hmmm, maybe THAT should be a new project.  Like I NEED another project.
   
  Pete


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## Nixon

Thanks for the input Pete.
   
  Mainly making it tube powered so I can get use to working with tubes, will have a crack at a Starving Student after this one.


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## dsavitsk

pmillett said:


> Though a tube is certainly a novelty, maybe a single-ended JFET stage is more practical.  You can get a JFET circuit to sound and measure an awful lot like a SE tube.




Might be useful: http://www.radiomuseum.org/forum/the_trioderizer_a_solid_state_triode.html


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## nikongod

Quote: 





nixon said:


> Mainly making it tube powered so I can get use to working with tubes, will have a crack at a Starving Student after this one.


 

 Just build the starving student. Its fun, easy, relatively safe, and well documented. 
   
  Building a portable tube amp combines all the challenges in building a tube amp with all the challenges of building a portable amp WITH challenges that are unique to a portable tube amp.
   
  The problems & solutions in portable amps and stationary tube amps are well documented all over the place. People have been thinking about & solving these problems pretty much forever.
  The problems & solutions in a portable tube amp are not so well documented. If your comfy figuring out how to solve a problem you may encounter on your own, go for it. If not stick to well documented projects where you are less likely to have problems.


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## bengoshi2000

"Portable" probably means different things to different people. For me, I want an amp that's easily moved, but I don't plan on using it while in motion. I love my Starving Student, but I do get tired of lugging it from room to room. And clearly I couldn't use it in the vanpool on the way to work. . 

I'm also keeping my expectations in check... this project won't rival the sound of my Starving Student, I'm sure. 

At the end of the day, I just want to see if (considering my minimal skills) I can build something that works!


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## mfm123

hmm i went around looking but never found anything about using the 6111. Is it possible to recreate the oakley k272a circuit for the 6111. Also what's the diff between the 5pin of the 6814 and the 7 or 8 (not sure) of the 6111?


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