Tube headphone amp kit for $25!? - Page 7

Do you know something about Jamicon caps?
I've found 4 caps on a old Creative soundcard, if they are good i can use them in the amp

are very similar to this:
http://img90.imageshack.us/img90/393...tal1ty3xt6.jpg

In a word, no, the Jamicons are dead stock items, as far as I'm aware. You really need to buy Nichicon Muse or decent Elna caps (Silmics or Cerafines) to name just two brands if you really want an upgrade.
I got my new amp up and running properly last night, with the stock opamps, and it was a hoot to listen to music through! Plenty of pace and very good clarity, great with the 32 ohm Denon AH-D1000's and not so with the Sennheiser 650's, which need more grunt to run well. As much fun as that was, I just had to pop in a really great opamp into the output amp position, having readily on hand a good selection I chose my current opamp fave, the plug in dual AD825 board ie, two single channel opamps on the one board. Within one second I knew it was a sensational choice! Gobsmackingly bigger, quieter, faster, punchier and all round superior, I was still listening hours later until well after midnight, wanting to find more and more tracks to listen too. Entrancingly communicative, this is a really terrific preamp/amp, while great fun as a stock unit, it really responds to upgraded parts remarkably.
Sure, the AD825 board doubles the overall price ..... and that makes it still only about $75NZ! Add the caps upgrade and a case etc, and you're at $100NZ for a wicked little amp that can truly sing, has loads of clarity and fine detail without sounding either soft or edgy. Brilliant!
Despite other saying how microphonic these little tubes are, I am still amazed at how much so that is true, I've never heard anything that rings at a level these little suckers do! It takes nothing to set them going into an extremely high pitched tone that must annoy the hell out of any dogs nearby.
Blutak works to a degree, but they will still ring with little provocation, so I went out and bought some tight fitting grommets, loosening them up by opening up a set of long-nosed pliers inside the grommet for a minute or so and they went on somewhat easier after that.
The amp sounds fabulous connected to the dock output of an iPod Classic, playing Apple Lossless files.
Here's a couple more pics from the testbench, pre casework.

wow really nice!
I've received my kit today and I have finished to solder everything five minutes ago, it seems works.
I think to buy some elna caps on ebay soon and change the C1, C2, C5 and C6.
I have also a potentiometer but it's of dubios quality, I don't know if mount it...
I cannot wait to try it with my akg 240
Why do you changed also the C4? I think to mount the IC directly on the board and avoid the sockey
Work in progress..and news incoming
Bye!

Ground problem?

I've try to use the amp but i think to have a ground problem, infact i can hear something only if a put the fingers on the pins on the base of the tubes, without fingers comes only noise from my headphones.
Can be fault of the supply or somethin with a bad soldering?
If the trimmers are on the default position the volume is very low and bad
Thanks in advance

Mmm, have you checked to make sure that both opamps are in exactly the right way? The little notch in BOTH of the opamps must be at the headphone end of the socket. If you've got the socket round the wrong way, it's ok, but you MUST have the opamp facing the right way. BTW, I don't recommend soldering the opamp directly to the board for three reasons; 1) The just mentioned reason in the previous sentence! 2)unless you are really good with a soldering iron, don't. 2) you're going to make it very difficult to pop in other and superior opamps!
Another thing, have you made sure that the valves are in the right way? Sounds silly and I hate to think that I'm insulting your intelligence in any way, netsky3, but it can be done. I'm going to assume that you've soldered the side of the valve (tube) with the red dot to the square pad on the board?
Also, are all the caps in the correct way? The long lead of each cap goes into the positive (+) pads on the board. The negative side is marked on the caps. The only exceptions are the 0.1uF poly box caps.
These valves ring like I've never heard before! They simply must have tube dampers on them and grommets really do work very well. A BIG however here, put them on BEFORE soldering in the tubes! I damaged one of the little suckers trying to get a grommet on like that and had to remove the whole thing - not fun with through-soldered boards - and start again with pre-grommeted tubes I'd done for the second kit. Seriously, you could send the local canines wild with the high pitched ringing from these things!
I've been experimenting this morning with another fine opamp, the OPA627, also on a little board like the AD825, and it's a stunner! Both of them are, just a little different in presentation, I'm going to write more on this in a new thread. The best reason NOT to solder in the opamps!
Cheers and happy soldering, S-man

P.S. Send me a good pic of your board if you're still not sure.

OK, news:
- caps are soldered correctly
- opamp idem but one doesn't have a good contact with the socket
- tubes are installed correctly and now have a rubber around them, no strange noise on my headphones
- resistors are ok
The volume is not so good, i must turn completly the trimmer to the max gain, I don't know if this is normal but I hope no.
Soon I think to change the opamps and the the caps, I cannot wait!
Sorry for your pics and your help
Cheers!

Something is definitely wrong somewhere. Can you send me a pic of the board? What's the problem with the opamp? IS it in the right place? Sorry to ask that question, but hey, it's been done! ) Are any of the opamp legs bent? What are you using for a source? Before connecting anything else, netsky3, do reduce the volume to a low setting! Did you damage a tube in any way putting the grommet on? Are any of the legs touching each other? Lots of little things that can cause BIG problems. If there is a basic problem here, adding better parts will not work unless the circuit is working properly in the first place. Let's get the basics right first, eh?

AHHH!! Netsky3, the LEDS,

I'll send you a pic tomorrow or in the next days
opamp are placed correctly, the source i've used are: the headphone out of my notebook and the line out of a portable cd player.
On my tubes i've put a sort of gum like the first u have used on your pics and they are still working, nothing damaged.
I think i've done a pair of bad soldering in the rush and my solderin is presently broken. :/
I'll re-check the soldering as soon possible.
The led L1 flash for a second when i connect the amp to the supply.
Thanks for all
Cheers

AHH! Netsky3, the LEDs! Are they in the right way round? These are tricky little suckers, as they don't have a flat on one side to mark the cathode as many do. Diodes the right way? I have a pic here, as close as I can get to the diodes and LEDs in question. See how the diodes are facing with the little black bar on the LEFT HAND end of them here? Ok, you may have done that just fine, however, the LEDs must be facing the right way too, not just either/or. BOTH of them and they both face the same way.
You may have missed the fact that one of the legs of the leds is longer than the other, the long leg is the anode (positive leg) and must face to the right side of the pic. Normally, there is a 'flat' bit on the base of the led to show you the cathode side (negative), but it seems to be non-existent in these ones.
Tricky, it is, now that they're soldered in. Have a close look at an led, you'll see two little metal electrodes inside, the anode (longer leg) has a smaller bit inside the plastic bulb, this should be on the right hand side of the board as I've photographed it. Desolder them and switch them around if you need to, as long as both leds are the same way, you should be right. At least you will have eliminated a suspect if they're ok. Sorry it's a bit long-winded, S-man

P.S. I have added this little bit 'cos I've been doing some experimenting and discovered that the amp will work even if the LEDs are round the wrong way, at least if both of them are ie facing the same 'wrong' way
So, now I can ask, does the LED nearest the 3V battery pack - the one below the opamp socket in the above pic - light up constantly with a little red glow? Does the other one give a red flash just for a second when the 9V battery is connected? It's supposed to stay off after the one second flash.

Nice work Sennsay old buddy !!!

Are there any tube equivalents to the stock ones supplied that could be swapped into this little bugger ? I've dealt with only one miniature triode before (the 6112's in the MF X10 V3 buffer I sold recently) so my knowledge of them is very limited.

Peete.

Oh Netsky3 I know all about Jamicon caps...stay as far away from them as you can. They are cheap cheap cheap like Teapo and some other dirt cheap rock bottom priced parts. It's better to stick with known quality brands like Panasonic, Nichicon, Elna, Rubycon, BC Components, Vishay,Rifa,Eros,Aerovox BHC, WIMA,NoVer, Sanyo now Vishay-OS CON, Black Gate, etc....

Many of the quality parts aren't much more expensive (except for Black Gate which ARE expensive) than the cheap stuff so it makes little sense to use any suspect parts anyway. IMO at least.

Peete.

HIYA BUDDY! Great to hear from you! Haven't done any research on finding equivalent tubes, I'm just enjoying this fine little gem too much at the moment I'm already building the 'upgraded' model, just waiting on some more of the Nichi FA's to arrive. Haven't tried Silmics or Nichi Muse KZs yet. This little darling of an amp is soooo addictive to listen to! I've been up until after midnight for the last two nights with the Denon AH-D1000s on, finding track after track to absorb myself in. The Denons match this amp so perfectly, forget the 650s ..... though, rigged as a preamp (just by changing the output opamp to something decent like a OPA2134 or similar) and then running it into a KHA will be my next venture, then I can really use the 650s. Heck, the OPA627s might make a fine preamp output too. An HDAM is useless with a 9V battery supply, haven't tried it with two 9V batts in series to make 18V .... yet. I reckon an HDAM would need paralleled pairs of 18V to do it justice.
This amp majors on communication in a way nothing else in my inventory does (other than the Trevor Lees preamp) and it's sounds simply wonderful with Frankie ahead of it! Fed from an iPod, I find the AD825 board suits best, terrific focus and openness, whereas the 627s are just a little more laid back and just as wonderful, a touch softer with the 'Pod. Didn't like the 1364 here, dry and a bit uninteresting, though certainly very clean - probably needs more grunt, like 18V.
Cheers to you buddy

Found one, the CK512AX. Raytheon also make this tube, here's the pdf wot I found:
www.shinjo.info/frank/sheets/138/c/CK512AX.pdf
From what I've found out so far, there is little around with the in-line pin set-up of the JAN6418 and very little in an actual socket. At least you can gently bend the tube over to fit in a lowish case when a socket isn't involved

Actually, PP, I have Frankie, the TL preamp, KHA II and the Senns on right now and it's just like big daddy version of the little bub. Wow, like father like ..... son? Hee hee