Bypassing a 100uF output electroytic - which value?

[johnm]

I don't like the sound of Black Gates, and having to leave them on all the time is ridiculous, as is the 'burn in' time. I want to listen to - and enjoy - the music ASAP rather than wait 200+ hours for the caps to 'work correctly'. Not a good design IMHO, plus they're difficult and expensive to get hold of now. Not too keen on the sound of Silmics either - way too polite.

I'd heard the Nichicon ES with a small bypass were a good bet, but it seems non-polars should be avoided afterall?

[JC951t]

Hmmm, I never had to wait 200hrs. For me , I prefer the BG standard
over the rest especially for SS stuff. Warmer sounding which is a blessing
for SS stuff.

[johnm]

Plumped for the pair of Nichicon KZ's in the end for C77/C78 output duty, and I'm glad I did the 34 is singing away merrily now

Didn't make any mods, just replaced all the 100uF caps with Panny FMs, and the PSU section with Rubycon ZLs. Bypassed a few caps with wire links (following a session reading Keith Snooks superb website, plus the DADA Quad 34 upgrade instructions) but that's the extent of any changes to the original design.

Quiet surprised how good it sounds actually - certainly better than my 'hot rodded' earlier DIN socketed 34 which had all the op-amps replaced, hand matched resistors etc etc etc. I guess those TL071 aren't QUITE as bad as everyone makes out, and perhaps the circa 1988/89 revision circuit board is better than the earlier DIN versions. At any rate it certainly sounds far from muffled and grainy as many reports would have one believe. Nice and natural, warm midband, but with planty of detail and an unexpected bass punch!

Thanks for all the valuable opinions folks.

- John

[AndrewT]

what does the tl072 do?
Is it only handling infra audio signals?
If so then tl072 should have no effect on the sound quality.

[richie00boy]

Originally Posted by johnm

Quiet surprised how good it sounds actually - certainly better than my 'hot rodded' earlier DIN socketed 34 which had all the op-amps replaced, hand matched resistors etc etc etc.

Just goes to show that messing about with things isn't always better

[johnm]

Without a doubt! Quad obviously knew what they were doing, even if many do consider them 'too polite' and/or unfashionable. I think perhaps Quad did themselves no favors by usually going for the cheapest caps they could get their hands on (which Quad themselves have admitted - just wish I could remember the article). Upgrading these to superior 'industrial grade' caps like the Panny FMs and Rubycon ZLs appears to have realised the full potential of this design.

Heck I was playing some Metallica earlier and the 34 didn't sound in the least bit slow or congested... (it will never be as transparent as a really good modern pre - too many op-amps and CMOS switches for that - but I'd still class it's performance in the 'v.good+' bracket). In short, I'm very happy

My earlier 'super' modded Quad 34 is sitting in the corner looking very sorry for itself

- J