A Super-Simple 6DJ8 Headphone Amp - Page 31

 

I have a few NOS 7DJ8, they are practically identical to the 6DJ8 and sound great in this amp. But it would be uneconomical to ship them to the US... Check on ebay, a single tube won't cost much.

Yeah, not too expensive, I just wanted to show off my rig to the only other audiophile in my family (my dad) when I drive 11 hours tomorrow to go see him. It's just bad luck.

Would this pair (so I have a spare) be a good value?
http://www.ebay.com/itm/2-Vintage-JAN-Sylvania-6DJ8-ECC88-Stereo-Tubes-/181023926212?_trksid=p3284.m263&_trkparms=algo%3DSIC%26its%3DI%26itu%3DUCI%252BIA%252BUA%252BFICS%252BUFI%26otn%3D21%26pmod%3D400340551355%26ps%3D54

How about this one?
http://www.ebay.com/itm/1956-FOIL-RCA-5963-12AU7-12AU7A-BLACK-PLATE-Vintage-Amp-Audio-Radio-Tube-Valve-/160926216892?pt=Vintage_Electronics_R2&hash=item2577f332bc

Woah!
http://www.ebay.com/itm/12AU7A-Sylvania-vacuum-tubes-38-tested-strong-made-in-the-USA-/190754532129?pt=Vintage_Electronics_R2&hash=item2c69db2b21
Edited by Evshrug - 11/20/12 at 6:33pm

Are you certain the 12AU7 can be used as a replacement for the 6DJ8? Retailers seem to sort these as two different types of tubes. I'd verify this amp can use a 12AU7 before buying a new tube.

You know, I think you're right. I must've gotten the tube families mixed up from researching the bravo/indeed amps. After my last post, I found this resource... A good one?

http://www.audiotubes.com/6dj8.htm

Zigis' amp has been maintaining itself as my favorite, really enjoying it with my Sylvania and Bugle Boy tubes; I have some Vokshods now too, but I haven't had the time or compulsion to roll them in yet, the ones I have tried sound so good! Stuck on the Bugle Boy right now. Zigis sent me some new side plates, but I'm trying to find the right kind of screwdriver head to put them on.

Evshrug, you need Hex key or hexagon L key, something like this

 

 

They are available in any hardware or building material store. 

For screws in amp you need only 2 mm bit, buy smallest and cheapest set. I hope metric hex keys are available in US.

 

Something like this:  http://www.harborfreight.com/fold-up-hex-key-set-94589.html

 

I'd be surprised if you could find cheaper than Harbor Freight (though it's definitely possible).

 

I find cheaper in the same place :)

 

http://www.harborfreight.com/10-piece-hex-key-set-94597.html

Zigis, did you by any chance manage to alter the design of your board so that larger capacitors like the Elna Silmic II can be used? If so I'd be interested in getting a board...

I finally located my tool case, has a bunch of sprockets and tools, including a large variety of drivers, but no allen wrench small enough for the 2mm screws. There's a local hardware store... I probably would not be able to find a set for $2, but it might be cheaper after the $9 total price from harborfreight if you consider shipping. And maybe, I could just take the amp with me and I could borrow one for 5 minutes, they let people borrow tools at the auto parts stores.

 

Can't help but notice the irony... the set you found, called the Pittsburgh... I live in the city of Pittsburgh. LOL.

 

Ludoo, It's up to you, but I am already very impressed with the amp built to it's current spec. What do you expect the larger caps to do, increase bass extension? The bass extension already matches (mostly) my FiiO solid state amp (without boost), with my Amperex 6DJ8 "Bugle Boy" and Vokshod 6N23P tubes I don't feel like anything is being "held back" on this amp. Maybe you know something I don't, but the sound is already "enthusiast grade."
Edited by Evshrug - 3/28/13 at 7:37pm

I already built one with the original board and "audiophile-grade" components, look at the start of this thread. :) I simply want to make another with the same components, and Ziggy's board design would allow me to use a smaller enclosure.

 

Excellent caps cost only a few euros/dollars more than good ones, I think in this case it's a good investment. The difference is slight but audible, it makes no sense to skimp on five capacitors when the difference is maybe 5% of the total cost of the build. The problem though is that audiophile grade caps are much larger than regular ones, they fit on the original Chinese board but not on the redesigned one.

Edited by ludoo - 3/29/13 at 1:20am

Oh, I read through the whole thread before I first posted last year. But what, exactly, do the larger capacitors do?

 

They are larger only in the physical sense. The difference is in the capacitor quality, and the fact they are made specifically for audio (eg Elna Silmic II).

I did not notice Pittsburgh name before :)

 

If I had known that it is so complicated, I would have added to package one 2mm hex.

ludoo, sorry, only old good design PCBs available :) 

New design cost much and I myself don't need larger caps so much.

 

If I where you, I make it creative way. With little legs bending 16mm caps (470uf Elna) will fit, I think. You may change C2 output caps and maybe C3 second stage power caps too.

C4, first stage power cap is not so sensitive.

 

Output caps you can solder slightly above surrounding small resistors, or solder resistors on boards other side. I am sure, similar creative way you can push in C too.

Edited by Zigis - 3/29/13 at 2:37pm