Whats everybody's favorite capacitor for audio filters?

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wkbdgeorge

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Dec 19, 2008
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I'm not sure if this has been a thread of its own yet.  I think it would be interesting.  Whats everybody's favorite capacitor for audio filters?  High pass, low pass, pass pass.  polyester? polypropylene?    What say you?
 
My favorite is polystyrene, but these are not available in large capacitance, and not very robust for commercial manufacturing processes.

Polypropylene is a good more robust alternative.

It depends somewhat on the application but for EQ or poles in the middle of the audio band, capacitor linearity matters.

JR
 
I did search film capacitor, and although different threads may talk about this in slight detail, its not the main focus.  That is why I thought it would be a good thread starter. -g
 
Studying capacitor data sheets will reveal several ways that they vary. How audible these variances are depends on the application.

If serious about understanding how they vary in real use, nulling out two identical circuits with the only difference being the type capacitor used will reveal exactly how they vary. You can measure and/or listen to this null but don't overestimate the significance of any difference if you apply gain to the nulled product to hear it.

JR
 
Is there going to be any sound difference between say, an orange drop and a metallized polyprop by illinois cap? etc...

In all of the threads that you could have read through, here and on the internet in general,  you would see a very distinct consensus on capacitor sound pertaining to their chemical makeup.

And that consensus is that nobody can give you a firm and straight answer.

Yes, I said it, nobody will be able to tell you how anything will sound in any given situation.  Each cap will sound different in different applications, even when the models used are the same.

So I say forget about finding the *perfect* cap because it's a wild goose chase.  You'll have gone off and spent too much time and money chasing something that nets a very small amount of change before you realize that you really can't tell the difference as long as you use something that's decent.

I'd say use non-metalized polypropylene or PPS film for everything and forget about the rest.
 
What Svart said.

If you still want to read more about it, have a look at the Passive EQ META. Other useful search terms include pultec passive eq wima solen film polystyrene polypropylene capacitor cap ; try a few combinations of those. As Samuel indicated, this has been discussed in detail quite a few times.

JDB.
[and don't forget to look at the 'build finished'-threads in the Lab; several EQ builders have talked about their own personal cap preferences]
 
What if it is a metallized cap?  What is negative about that?  For example.... im having a very hard time finding a 1uf non-metallized polypropylene.  They all seem to metallized for 1uf
 
I recently went through a decent amount of caps in 1176. The compressor is so fast, that all audio caps have a distinct effect on transients, and those can be heard easily with listening tests and when null testing between two channels.

http://www.groupdiy.com/index.php?topic=33834.0

I basically found out that polypropylene or polyester film caps nearly always sound best in this circuit, and that the quality electrolytics I had chosen, while colored, could be used instead of those big film caps when "voicing" the circuit. Sometimes they just sound good.

We are still talking about fine tuning the most extreme ways. These are very subtle differences - negligible to most people I think. Get your circuit working first.
 
Thanks Kingston,  I appreciate the direct response.  Its hard to get that sometimes.  That 1176 looks very interesting.  So its another vote for just polyprop.  What is it about metallizing of the caps that isnt desirable?  I thought I read in another posting that someone liked a metallized polystyrene.  Maybe I am mistaken.
 
old wimas

the foils are stacked instead of rolled.
less inductance.
better bass.
more highs.
crispy mids.
delectable decibels

those old nazi's built some mean amplifiers.
 
What is it about metallizing of the caps that isnt desirable?

Film/foil structure will work better in high energy use with steep pulses. But for audio, at least one thing could matter. Metallized foil caps have very thin layer of aluminum and they are self healing, which means that the aluminum will evaporate if the dielectric is locally broken, and thus "self heal". In film/foil caps the foil is thick and self healing doesn't happen. Therefore the dielectric must be much thicker which then means low dielectric losses. I don't know if that matters, but for small values I use those, they are quite inexpensive these days up to 10 nF and basically pretty much comparable to polystyrene in objective performance and they withstand higher voltages which is needed in tube gear.
 
wkbdgeorge said:
I thought I read in another posting that someone liked a metallized polystyrene.  Maybe I am mistaken.

Remember, these are very subtle differences, and in some circuit it is entirely possible metallized polypropylene sounds best. or the cheapest electrolytic you can find.

There is an easy way to solve this. Build a circuit, and start swapping caps. Maybe you won't hear a thing, maybe you'll find some caps work better than others. Caps are cheap enough so you can buy a set for just this purpose.

I have not seen any listening tests on this topic I would consider trustworthy, and I don't think there can be any. Not everyone likes the same things.
 
just grab any old capacitor, solder it in there, and then RECORD SOME ROCK 'N ROLL!!!! and.... if you don't like it, try another one. never take someone's word. sound is subjective. you have to use your ears and trust them.
 
Kingston said:
wkbdgeorge said:
I thought I read in another posting that someone liked a metallized polystyrene.  Maybe I am mistaken.

Remember, these are very subtle differences, and in some circuit it is entirely possible metallized polypropylene sounds best. or the cheapest electrolytic you can find.

There is an easy way to solve this. Build a circuit, and start swapping caps. Maybe you won't hear a thing, maybe you'll find some caps work better than others. Caps are cheap enough so you can buy a set for just this purpose.

I have not seen any listening tests on this topic I would consider trustworthy, and I don't think there can be any. Not everyone likes the same things.
Swapping caps especially old, is a little risky isn't it?

Is there a circuit that one can build that you connect the actual unit to that is the middle man between the interchangeable caps and the actual unit, that way it will blow the circuit first before the equipment.

eg.
cap --> DIY circuit --> actual unit.

Right now, I do the interchangeable caps thing direct on the PCB board, on pic 8.
http://www.groupdiy.com/index.php?topic=34412.0

 

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