Fancy Audio Capacitors

[Tenson]

Hi,

I have not really been a believer in big sonic differences between capacitors, but I am considering trying a more fancy cap for the one in series with the tweeter in my speaker.

Currently I use a 100Vdc Polyester film.

I am aware that some types of cap are more linear such as polypropylene or paper in oil. However, the majority of 'fancy caps' for audio seem to be rated for at least 400Vdc. MY question is this - is there an advantage to 'over-rated' caps for audio use? In my application I doubt it will get anything more than about +/-40V swing from the amp so 100Vdc seems suitable, but does distortion reduce for an overrated cap?

Please keep your answers to objective comments. Subjective opinions on cap sound quality are not really what I am looking for.

Thanks very much!

[analog_sa]

Originally posted by Tenson
does distortion reduce for an overrated cap?

It doesn't. Most of the companies manufacturing what you call "fancy" capacitors have special low-voltage lines for speakers.

It seems that capacitor "sound" is different between high voltage and crossover applications ie a very well regarded coupling cap may not perform so well in a crossover. One reason may be the lack of (high?) polarising voltage in most crossovers. A capacitor with a higher rating will appear to be at a disadvantage as it has more dielectric to polarise.

[Tenson]

Thanks for the reply. It was my limited understanding that only a limited types of caps require a bias voltage to perform well? I have not heard of polypropolyne needing any bias voltage for example to work well. Tantalum as a coupling cap on the other hand...

So you think a 400Vdc polypropylene caps is likely to not perform so well in a crossover as a 100Vdc cap provided the signal is not over that rating?

[bacon665]

Wouldnt a set up like this allow for proper bias of the cap.


This way the woofer acts as a drain on the cap but not all the signal is FORCED through it. If the cap is just put in parralel the roll off isnt that great because signal can bypass it.

Sorry about the pic i made it in paint in < 1 min

[analog_sa]

Originally posted by Tenson
So you think a 400Vdc polypropylene caps is likely to not perform so well in a crossover as a 100Vdc cap provided the signal is not over that rating?

I don't really know. Assuming that any dielectic, other than vacuum has some non-linearities it makes sense to limit the amount of dielectric to the minimum voltage requirements.

JBL knew about biasing many years ago when they designed the crossovers for K2 with a 9v battery. How tweaky is that for a company like JBL?

[analog_sa]

Pre-bias capacitors in crossover

[theAnonymous1]

Originally posted by analog_sa
....it makes sense to limit the amount of dielectric to the minimum voltage requirements.

Unless of course you like to use SMD X7R ceramics. The higher the voltage rating the less "undesirable" effects they have.

But, what type of madman would do such a thing.



^^^^^^^^^^^^^
1uF 100V X7R (1812)

[bacon665]

i dont even see the leads D;

[Geek]

Reminds me of the blown insulation they used in the 60's

[infinia]

1uF 100V X7R (1812)

Nice chip caps.... those make excellent DC supply filters.
good for SMPS and maybe gainclone pin decoupling... but not for audio signal path blocking and feedback use.

X7R ceramic dielectric is very microphonic in high impedance circuits.