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Tube headphone amp kit for $25!? - Page 2

post #16 of 213
Well, I've finally gone and ordered a kit. Hope to put it together over thanksgiving break, if it gets here in time.
post #17 of 213
Sweet little tube amplifier indeed!
post #18 of 213
Very cool work, especially building a balanced amp. Would make for an interesting transportable amp.
post #19 of 213
wow this looks perfect for a beginner wanting to get their hands dirty...since it is a kit later on do we have the option of running any kinda of tube amp we want?
post #20 of 213
Thread Starter 
I have been enjoying this amp so much. To my ears the magic is in live or acoustic instruments. Classical, jazz and none electric pieces just comes alive. Old recordings 60's, 70's and 80's recordings all of a sudden sounds like it just has been remastered. I am so happy that I took a chance on this kit.

Just in case anyone is worried that this little amp can drive full size cans. It has more gain than any headphone output that I've listen to before.
post #21 of 213
OK you've got me, I've ordered one...
post #22 of 213
Tempting. I'm not clear on how you got balanced drive, though. I see two boards... one driving positive and one driving negative? The price seems right to build a nice little balanced amp.

I should resist!

Edit: I see it uses internal trimmers for the volume adjustment... could those be run to a normal pot? For the balanced, would a four-gang pot work to control the whole thing?
post #23 of 213
In theory could this be used as a unity gain stage (by using two amps for balanced operation) to convert a SE'd analog output stage of a DVD player to balanced output ? All I would have to do is take the +/- gnd feeds off the L/R channel I/V conversion stage to the dual amp boards, set the trimmer gain to 2.0V output and whoila a balanced analog out for a DVDP ? Of course I'd need to install the XLR jacks/ hook up wire, get the boards a steady feed of clean power but that's the easy part....

I'd follow the builders lead and add the second 9V cell Sunneebear Nice work BTW and a really cool find. You should try out the Jaycar SS head amp kit it's equally impressive and just as affordable.

Peete.
post #24 of 213
Thread Starter 
Thanks Peete, the truth is I had to ask around a bit cause this is my first time with balance. I could have used the 9v's but I have a lot of rechargeable AA and a handful of eneloops so I just put it to good use. I'll look into the Jaycar.
post #25 of 213
So I started putting my kit together yesterday, got most of the soldering done. Had to run out and grab some more parts and I finished it an hour or two ago. I couldn't find a suitable case either, but I eventually dug one up and had a load of trouble cutting holes out.

once I had everything set, I plugged it up and I thought "what the hell is this sound? It's all distorted and bad!". Then I realized the gain switches were high and turned them down.
Now my problem is that I have to turn it up almost all the way to get reasonable volume from it. I think it might be from the pot for the volume. It gets loud enough, just a little surprising how much I have to turn it up.

From my brief listening so far, the first thing I noticed was increased bass presence. The sound is warmer and smoother. Hope to get some more listening tonight.

I'll add some pics in a little bit.
post #26 of 213
I just got mine built ( had an friend at work help me with the board layout) and have burned it in for about 30 hours this weekend. Hooked a used battery up to it and it's still going strong. Now that it's working I'm going to mount it in the case I made and use 2 9 volt batteries in series so it should last awhile. I can't beleive the volume it puts out. I have sennheiser cx-300b earbuds and I believe I could blow them if I turned the potentiometers up the whole way! Built this a work so I can't wait to get it home to try it out with my hd265's! It's alot of fun to build and impressive sound for a small package.
post #27 of 213
You would want those batteries in parallel, not series. Series will overvolt the components to 18V, which will blow them up depending on their specs. Parallel wil maintain 9V, but will draw the power from each battery equally, thus doubling run time.

-Nkk
post #28 of 213
Yes, your right Parallel man these 12 hour shifts are starting to burn me out!
post #29 of 213
Lol. No worries. I actually just PMed you to make sure you stayed safe and did not blow a cap in your face or something.

-Nkk
post #30 of 213
Here are some pictures of what I slapped together. I can't figure out why I have to turn the volume knob up so much before it reaches reasonable volumes.

I seriously need to have the knob at 3/4 for quiet listening levels. Anyone have ideas why this may be? If I turn up the gain, the sound gets dirty. I don't think the power switch would affect it. The potentiometer is a Panasonic something something, the same one that is recommended for cmoys on the cmoy website. this is the only thing that I think would be causing problems, but I don't understand why. Any help and ideas would be appreciated.

Otherwise, I'm enjoying this amp quite a bit. It's reasonably small and battery powered so it works well as a transportable amp.
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