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Civilian 6n2+fu32 tube headphone amp - Page 2

post #16 of 55
Very nice work.

I'd replace the headphone jack with a black 1/4" panel jack, like the locking Neutrik ones.

www.neutrik.com/en/audio/plugs-and-jacks/locking-1/4-chassis-jacks/nj3fp6c-b

Would match those excellent knobs, just sayin. biggrin.gif

Sent from my HTC Desire HD A9191 using Tapatalk 2
Edited by TrollDragon - 7/24/13 at 8:24pm
post #17 of 55
Quote:
Originally Posted by TrollDragon View Post

Very nice work.

I'd replace the headphone jack with a black 1/4" panel jack, like the locking Neutrik ones.

www.neutrik.com/en/audio/plugs-and-jacks/locking-1/4-chassis-jacks/nj3fp6c-b

Would match those excellent knobs, just sayin. biggrin.gif

Sent from my HTC Desire HD A9191 using Tapatalk 2

ummmm.. that neutrik headphone jack is nice...might consider that.

post #18 of 55
Let us know what it sounds like when you've received the tubes.

I would stay away from locking jacks for one important reason: should you, your wife, friends or children trip on the cord, the whole thing could crash. And it's akward always having to use two hands swapping headphones. I know, I have an amp with those jacks and I tend to use it less than the others because of that.

I'm sure Neutrik and other manufacturers have regular jacks that looks good as well. It' a kind of safety release.

Nice work, by the way!
Edited by MDR30 - 7/31/13 at 10:09am
post #19 of 55

Mine's arrived and although I haven't had a chance to listen to it yet, the build quality looks very good - a very pleasant surprise and far better than I expected. 

 

I have some NOS RCA 832As and a 6DT8 in transit too - really looking forward to playing around with this great little amp.

 

Regards.

 

Jon'. 

post #20 of 55
Thread Starter 

Been burning in my new Fostex T50RP ortho headphones with this amp & it seems to be a match made in heaven. This amp has plenty of power to drive these low impedence headphones, effortlessly. A 12o'clock setting is the max you need with these headphones & blows the AKG's away. No more very annoying sibilance, a ton of bass, excellent mids & a slightly rolled off treble which to me is perfectly balanced. Especially good for modern rock/pop recordings that all have way too much treble to start with. One ends up just listening to the music for long sessions as the balance is just right. Anyone who thinks these headphones do not have enough bass are using the wrong amp, no modifications necessary IMO, just partner them with the right amp, like this one. For $350 approx for amp + NOS + h/phones, this has to be one of the most outstanding bargains in head-fi.

post #21 of 55
Thread Starter 

Does anyone know what/where to purchase a rotary on/off switch to replace the existing power switch? Needs to have a 6mm shaft so I can match the new volume knob I installed. TIA.

post #22 of 55

Any more impressions of how this sounds?

post #23 of 55

I also got one just for kicks, since it is really not expensive...

As is unmodified, it is a bit on the clouded/muddy sort of sound, not very clear/sharp.  It does have good punch, but it really need to work on the detail side of things.

 

I've so far modded the input tube to take 12AX7 instead of 6N2P (I don't plan to tube roll through all of Russia/Eastern Bloc have to offer, so 12AX7 it is), and swapped the Chinese FU-32 for a pair of RCA 832A.  One interesting thing I found between the Chinese FU-32 and RCA 832A is that RCA's plate is like what you'd expect, uniform color, no scratch or other marks.  While the plate on Chinese FU-32 was really scratched up, not that it scratched through the plate coating, but it was quite visible.

 

 

Other than the tube swap, I've also replaced the pair of coupling cap in between input and power tube.  These cap is interested, as it uses ceramic housing, instead of the normal epoxy dip/plastic wrap.  Perhaps it was some kind of surplus high voltage cap re-purposed as audio coupling.  Since I have no idea how these if those cap are good or not, I swapped them for a pair of Bennic FPP 0.33uF/400V caps (It was 0.1uF, unknown voltage).

 

the amp is just back in one piece about 30 minutes ago, and I'm letting it warm up before listening to it seriously.  By warming up, that include the irons on this amp, as they tend to get pretty warm after a while.  Which does take a while. :P

 

 

 

Seriously, these tubes really light up pretty, especially if you dim the room a bit.  That alone might be enough for quite a few people to get them.

post #24 of 55

Follow up on the previous post, the amp with the following modification:

Tube:
Chinese Beijing FU-32 -> RCA 832A
Chinese Beijing 6N2 -> JJ 12AX7 (including Filament connection mod on the amp)

Cap:
Replace the unmarked ceramic 0.1uF cap with Bennic 0.33/400V FPP cap

 

A bit of tidying up of the connections, such as the cap is now wired directly across the input and power tube, instead of going back to the bus, routed round and round and then to the power tube.


After about 16 hours of continuous operation, the thing cleared up quite a bit, it is much better than what it was without modification.   I will swap in the Chinese FU-32 tube in a moment and see how much difference did that tube make.

 

====Edit====

Swapped the original FU-32 for about an hour, and couldn't stand the muddy sound.  Swapped back RCA 832A, and it already sounds better within a minute of powering up. :)


Edited by Maniac - 9/13/13 at 5:45am
post #25 of 55
FYI Neutrik locking jacks clamp hard on Viablue plugs, very very hard to remove. As stated previously I would avoid locking jacks.
post #26 of 55
Quote:
Originally Posted by Argybargy View Post

FYI Neutrik locking jacks clamp hard on Viablue plugs, very very hard to remove. As stated previously I would avoid locking jacks.


Or just remove the locking bit's... :D

http://www.head-fi.org/t/86990/guide-to-modifying-a-neutrik-locking-jack#post_1002790

post #27 of 55
Thanks, didn't see that thread. I'll give it a try. I have 2 of those buggers in my parts bin.
post #28 of 55

You can get one of those non-locking Neutrik sockets that is the same shape as the one in there, which will allow you to swap it in without any additional metal work.


Edited by Maniac - 10/9/13 at 11:40pm
post #29 of 55

Just received mine after waiting awhile. around $200 shipped from http://cart100.com/Product/23718020085/Fever_6n2_fu32_tube_amp_vacuum_tube_head/ca.

 

One of the FU32s didn't work out of the box. Replaced the tubes with NOS tung-sol 6ax7 and haltron 832As, sounds very nice!

 

Thanks for the review DavidK35.

post #30 of 55
Thread Starter 

Glad you like it, enjoying mine also, best value around for a modest $200 or so, very undervalued. Replaced the volume knob with a big

solid shiny bronze one, looks retro cool to me.

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