[sdiy] lowpass gate etc - the sounds of capacitors

[Roy J. Tellason]

On Monday 27 June 2005 07:03 pm, anthony wrote:

> Before I finish them up and can listen for myself I was wondering just what
> different capacitors can be expected to sound like in different audio
> circuits.

Well,  there was an article in Electronics World about that a while back,  but 
the difference they were talking about were so *miniscule* that I know darn 
well I'll never hear them!  But there are other considerations...

> I think the impact of each different type might be different for the
> different uses for capacitors in audio circuits - like feedback networks or
> coupling caps or caps in a filter.

Yep.

> In my circuits I'm using all polystyrene in one and a combo of polystyrene
> and silver/mica in the other.

Silver-mica tend toward smaller values,  I'd guess.

> I had thought about using NP0's because I had this funny idea that they
> probably sound better than most any other ceramic. But then I decided that
> this was probably silliness and decided to not use any ceramics at all. Do
> ceramics really sound all that bad?

It's not a question of sounding bad,  necessarily.  They seem to find a lot of 
use in RF circuits for some reason.  They're also pretty commonly used as 
bypass caps.  But for filters,  or other applications where exact value is 
important they don't seem to be all that commonly used.  The tolerances on 
some of them are also pretty wide.  I found a chart somewhere that explains 
those cryptic codes you find on some of them,  somewhere out there on the 
'net...

> I've never actually taking the time to compare the sounds of variosu
> capacitors. What would be the best kinds of circuits to use to test how
> capacitors sound? I've been wanting to make a headphone amp out of some
> medium-mu twin-triodes - maybe that'd be good.

A while back I got a hold of a 567 chip and decided to play with it a little 
bit.  So I breadboarded a circuit,  tried it out by setting up a 555 chip to 
supposedly the same frequency,  and it didn't work.  I got no output when the 
signal was fed into the 567.  At some later point I took the ceramic 
capacitors out of the breadboard and tried some other kind,  I think 
polystyrene or similar.  It then worked!  Whether this was an issue to do 
with tolerances or something else I'm not sure.

Anyhow,  regardless of "how they sound",  I'd leave ceramics to RF, bypass, 
and similar uses,  and stick with mylar, polystyrene,  and similar units for 
anything else.

I've certainly got a well-enough stocked junk box to not have to worry about 
it any more...