Tube headphone amp kit for $25!?
May 4, 2010 at 8:11 AM Post #181 of 216
Quote:

Originally Posted by netsky3 /img/forum/go_quote.gif
Now my amp is running with two 9V batteries (18V) and seems to be better...
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Have you seen this product based on the K272 amp?
DIY Audio Projects - Hi-Fi Blog for Audiophiles: DIY Tube RIAA Phono Preamplifier Kit



Just checked that little sucker out and I love it! That's the next kit for me, I reckon
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I like the circuit that allows one to match the valves - very loosely, by the sound of it, but a lot better than nothing.
I need to get a stock of those JAN valves though, especially if I get any more of the "ring-meister" jobs that is in the left channel of my second amp! Once that thing starts ringing, the only way to stop it is turn it off. The first little kit is just the best fun and sounds terrific!
 
May 4, 2010 at 8:57 AM Post #182 of 216
Quote:

Originally Posted by studeb /img/forum/go_quote.gif
They also have an amp with a 6418 driving a LM1875 chipamp


They sure have some interesting kits on that website, eh? Like the sound of that one too.
 
May 11, 2010 at 4:42 PM Post #184 of 216
 
Quote:

Originally Posted by sennsay /img/forum/go_quote.gif



 I need to get a stock of those JAN valves though...

 

Feast your eyes on this:

 


I wanted a few spare tubes for when it's time to change worn tubes. At 1 euro a piece they're a bargain IMO.


 


My take on tube dampers:


That's approx. 32mm of silicone tubing with the side cut open. Works OK.


 


Here's mine:



The blue 0.1uF caps are Vishay-Roederstein MKP1837's. The two big-a$$ caps are Elna Silmics, they barely fit the space. Both Elna's are bypassed with MKP1837's on the reverse side of the PCB. Opamp socket upgraded to a better one, additional decoupling (rail to rail and rails to ground with 0.1uF ceramics on the reverse side of the PCB). All resistors are metal film types. Trimpots are Piher's. The tube sockets are my "invention", they're cut up IC sockets. Makes replacing the tubes a doddle. Currently sporting a OPA2134. The sound? Lush, warm, musical

Still needs to be boxed up though... 
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May 13, 2010 at 2:00 AM Post #187 of 216
The blue 0.1uF caps are Vishay-Roederstein MKP1837's. The two big-a$$ caps are Elna Silmics, they barely fit the space. Both Elna's are bypassed with MKP1837's on the reverse side of the PCB. Opamp socket upgraded to a better one, additional decoupling (rail to rail and rails to ground with 0.1uF ceramics on the reverse side of the PCB). All resistors are metal film types. Trimpots are Piher's. The tube sockets are my "invention", they're cut up IC sockets. Makes replacing the tubes a doddle. Currently sporting a OPA2134. The sound? Lush, warm, musical

Still needs to be boxed up though... 
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Well done, beftus, like your thinking there! In my experience the Silmics will certainly "lush" things up a bit in themselves :)  Love the tube sockets, now that's creative thinking! In my 'upgrade' amp, the left channel tube just about permanently rings like a tuning fork, dammit, so I've got basically the whole kit to desolder to remove the flamin' thing ...... muttermuttergrumble ...
 My Denon 1000s don't need lushing up and the AD825 board is remaining my favourite opamp in the first amp which is still running like a champion, bless it's little cotton socks .... or iddybiddy tubes :)
 Did you buy the spare tubes directly from Oatley Electronics?
 
May 13, 2010 at 2:07 AM Post #188 of 216
"IMO this is not suitable for use as a portable as the tubes are very microphonic. The tubes ring like "pitchforks from hell" someone once remarked..."
 
 
I agree for the most part, listening while moving would be like walking to the sound of tuning forks ........... yeah nah! Even plugging the headphones in sets 'em off, though they settle fairly quickly.
 
Building the phono stage version and adding this little amp into the same box for a total phono headphone amplifier might be a nice idea, it's on my list in the near future.
 
May 13, 2010 at 5:50 AM Post #190 of 216


Quote:
I didn't buy the tubes at Oatley. I found a surplus store in the Netherlands that has them. They also sell JAN6088's.
 
AD825 you say? Hmmm, must try that one too... 

Yup, absolutely my fave opamp board with the Denon cans, which totally love 'em
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Bass is better with these (dual single channels on the one board) than anything else I've put in there, even the excellent OPA627s. Depends too on what my source is, but with the iPod Classic sending signals from the dock port, AD825s sing.
 What cans are you using with the 2134, Beftus? Easy or hard to drive?
Be interested to hear your thoughts on the AD825s should you get a board or two, I have a good ebay seller that has them if you need to.
 
 
May 14, 2010 at 1:36 AM Post #192 of 216
Hm ... quite possible the AD825's will go well with these little cans, Beftus, shame I don't have any around to try out for you. Be interesting to hear of your findings.
 
May 15, 2010 at 10:17 PM Post #194 of 216


Quote:
 
Oh boy, I'm distracted by the Starving Student... If I can get the 19J6 tubes for it I might make that one before looking into the AD825.

Yep, that's a distraction all right
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Jun 6, 2010 at 3:13 PM Post #195 of 216
I followed sunneebear's example and made a balanced amp out of these little guys. Probably for the same reason-- I have a Matrix mini i DAC, and wanted to see what a balanced amp was like, without shelling out hundreds for amp and cables. And it does sound great-- at the moment I'm just listening to it for fun but eventually I'll be curious to compare it to other amps.
 
I was trying to keep the cost, cable included, to about 100 bucks, but I'm guessing it was about 150 in the end. I bought two stock boards on Head-Fi, one working, one with a few solder bridges I was able to fix, so that meant the amps themselves cost even less than the kits. The enclosure was free; a few years back I bought a TDQ-150 tuner on eBay. It didn't work so the seller sent me a second one. (He was dismantling a station and had a bunch.) The quarters were extremely cramped, and that slowed me down a great deal; I'd get a certain amount done one weekend, then spend a week or two trying to figure out the next step. The Neutrik jacks on the front were the hardest to deal with. I had a stepped drill bit that was just the right radius-- if you didn't count the little nubs and ridges all over the Neutrik jacks-- and filing the basic holes down to match the jacks was the most time-consuming operation, as I tried a few approaches that didn't work very well first.
 
I broke apart a 9V Sony power source for the main source, to avoid swapping batteries much. The 3V batts I left in place as they don't need swapped often anyway.
 
So, for now, I'm just psyched that it works. It was way too loud so turned the on-board pots down a little. I didn't add a four-gang pot up front; I'll control the volume on my computer. Sounds like people were having uneven success adding pots and it would have been tricky squeezing one in, so I let that slide. Anyway, here it is:
 

 

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