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gavthirdphase 24th March 2011 12:43 PM

Sound characteristics of caps
While trying to research the difference in caps I found the following information. I have a few questions that I will list at the bottom;

Capacitors DO make an audible difference !

Electolytic and tantalum capacitors have very poor audio characteristics and should not be used in the audio signal path. Replacing electrolytic capacitors in the audio signal path of your amplifier or preamp with film capacitors will improve sound quality. Polyester (Mylar) capacitors make a significant sound improvement and are the minimum quality audio capacitors that should be used in the audio signal path. Better are polypropylene capacitors, and even better are polycarbonate capacitors when available. Polycarbonate film used to make polycarbonate film capacitors has been discontinued for several years, only a few companies have remaining stocks of polycarbonate film which is expected to be exhausted in the next year or two. Polycarbonate film capacitors are preferred to polypropylene capacitors when available because they have a very balanced, musical sound with very little coloration. Polystyrene (also called styrene, styroflex, or styrol) are in many areas superior to polycarbonate, and are mostly new old stock as are our polystyrene, the polystyrene film has needed for manufacture of Polystyrene capacitors has not been made for years. The very best audio capacitors are polytetrafluorethylene (Teflon) capacitors, but they are generally very, very expensive and available in only a relatively few sizes.

Firstly If I am making studio filters (ie efx) distortions and clones of old studio equipment would a musically better cap be too clean for my purposes as I am trying to add character to sounds? Do vintage pieces of kit owe there sound to less than perfect components. If so can anyone give me any information on the different characters of the different cap types.

Also if Electrolytic caps are not so great for audio could I just replace them in a design with a film caps with out any problems?

Any information or links to learning resources would be most appreciated



FurryAudio 24th March 2011 07:15 PM

There was a good study done in the 80s as I remember in one of the UK mags on capacitor sounds, I think its covered in Douglas selfs small signal audio design & self on audio books.

Yes vintage kit owes its sound to its components but the caps would be a minor component of that IMHO, however regarding whether you'd want 'clean' caps surely you only want the distortion that you're trying to add. I certainly wouldn't choose a 'dirty' cap to add a sound, but neither would I get a super audio oxygen free solid gold cap, something middle of the road should be fine.

DF96 24th March 2011 08:31 PM

How they are used can be as great an issue as capacitor type. Electrolytics are fine when used in the right place, in the right way.

wintermute 25th March 2011 12:59 PM

The first thing I would say about that text is that it appears to have come from someone selling capacitors. This bit

Polystyrene (also called styrene, styroflex, or styrol) are in many areas superior to polycarbonate, and are mostly new old stock as are our polystyrene
Is what makes me think it is an excerpt from a marketing blurb.

The cap sound articles mentioned are available - Home

The effects of DC bias on electrolytics distortion in the cap falicies article there was an eye opener! Especially considering I'm sure I've seen claims that biasing electros with a certain amount of DC improves the sound...... I'm still yet to read the capsound articles.

The main benefit of polycarbonate (from memory) was its temperature stability, in other respects polypropylene has better specifications (though they tend to be bigger). The generally accepted substitute for polycarbonate is PPS (Polyphenylene Sulphide) which I first used in bypassing applications around 7 years ago. Don't ask me if they sound better because I couldn't tell you ;)

I've also yet to read the Understanding capacitors articles available here TechDoc But I think that they will also be worthwhile reading.


gavthirdphase 31st March 2011 06:12 PM

Great Stuff
Thanks for the replys guys I will have a study of the articles and come back if there is anything i cant get my head around.


indianajo 31st March 2011 08:58 PM

Yeah, blanket condemnation is great for sales but not for science. At one point I had the Dynakit St120 working with ceramic cap in with signal 4% of voltage rating, electrolytic cap out with 50% of v rating DC bias. I also had the Peavey CS800s working with no caps in , out or through (without using the mike input). On my current speakers SP2-XT at 1Vpp out, the ST120 had a bit more hiss and a lot more gain, but exactly the same sound on top octave solo piano as the CS800s. Putting 3300 uf back to back electrolytics on the output of the CS800s made a shaky pitch sound, probably because they have a chemical event as they cross 0 V. Split supply transistor amps can't do DC bias on output caps. Film caps of 3300 uf are about the size of car batteries and over $100 each.
It's all the details. The reviled CPO ceramic caps sound better, actually, than the tantalums I replaced, which made frying pan noise from the day I installed them "new".
You can see the distortion specs of the SP2-XT at 1 W on the Peavey website support button user manuals button. Not "PA" levels until you approach the rated 128 DB.

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