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Hackernap C3, alternative to tantalum,

I get the impression C3 isn't super critical to sound
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Actually the feed back cap has a significant effect on the sound, a mil spec wet tantalum is the best I have heard so far.

Reason I mentioned the Nichicon ES is because I restore Reel 2 Reel tape machines for a hobby and all the Revox ones have all Solid tantalum beads in the signal path so I have tried a few different caps to replace them but the BP ES is the best I have tried so far

Alan
 
Pete I don't think they are wet tants they look like solid tantalums to me as the wet types have a crimped end on the case like this
138D826X9050F2 Vishay / Tansitor | Mouser United Kingdom
When I have tried the axial solid tants, not saying they are all like this but the two I tried had a very detailed but bright treble which I found fatiguing ultimately, wet tants different animal neutral, transparent, great imaging, just sound right to me, I bought 4 of them for £15 each years ago and I am still using 2 of them now in my NCC300 amps.

Alan
 
337alant said:
Actually the feed back cap has a significant effect on the sound, a mil spec wet tantalum is the best I have heard so far.

Reason I mentioned the Nichicon ES is because I restore Reel 2 Reel tape machines for a hobby and all the Revox ones have all Solid tantalum beads in the signal path so I have tried a few different caps to replace them but the BP ES is the best I have tried so far

Alan
Click to expand...

Im planning film/wet-tant for C2 feedback cap.
I was wondering if C3 (across tr5) would benefit from something other than a regular tantalum.
I'm not a huge fan due to reliability uncertainties.
As the voltage is low niobium becomes an option.
Not sure if this would be better than an electrolytic or if I'm just obsessing
 
C3 bypasses the Vbe multiplier transistor (which sets output stage bias)
I'd just use one good cap there, and actually, the total capacitance isn't critical at all - while even 1uF of compact film cap is enough (my choice in own non-Naim-based amps) - there's also no penalty for going much larger.

Nb realise the transistor presents a pretty-low impedance path in parallel with the cap, so actually there's not much to worry about here; not even leakage currents in the cap. Tant types are just fine; 10uf or rather more, likewise. esp since actually, the quasi-comp architecture cannot be perfectly bias-compensated for temperature - go find other things to worry about.
 
Thanks Martin.
I might go for a film cap which fits the space then.
I do worry about the life span of tants.
I'd go bc128 if I had one, but I'm sure I have a film something in 'stock'
 
Grog said:
I do worry about the life span of tants.
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No need to worry about c3 position though -it 'sees' a constant, very low-voltage application, and no large dv/dt changes (there's a constant-current through the VAS). A very low-stress application!
 
Thanks guys.
I ordered some of bc128s just to be obsessive!

Quick question.
R36, R14.
Board has them labeled wrong way round with 10k to 0v and 12k to D1/TR3/R17.
Assume it makes little difference, as C25 optional..
Just debating if it's worth pulling the resistors and swapping or to leave it be.
 
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