Capacitor audibility: fact or fiction?

[jcandy]

In the last few days I have been trying to sort out the issue of capacitor choice for use in passive crossovers. There seems to be an inordinate number of people (both seasoned designers and technically incompetent "audiophiles" alike) who express strong opinions and actual preferences for certain capacitors. For example, bizarre claims like "Xcap really opens up the speaker while Ycap sounds gritty" are not uncommon. Yet, I can find ZERO objective testing data. Not a single SPL trace.

Does anybody have some objective data on this issue. I've heard all the opinion, now I'd love to hear some facts.

[dantheman]

There is some evidence that caps can have an audible effect:

AES E-Library: Audio Capacitors. Myth or Reality?
and this discussion on it makes it seem more dubious:
Need impressions of capacitors
Then there is this:
ABX Double Blind Test Results: Capacitors

Don't set fire to your caps!

Dan

[badman]

Note that the listener environment was critical in the results... I've always said that listening in a home system at your leisure makes differences much easier to hear and interpret.

[jcandy]

No doubt a poorly-made capacitor will exhibit non-capacitive artifacts (that is, it will behave in a non-ideal way). I'm surprised we haven't seen anyone do some SPL and distortion sweeps using a selection of audiophile-grade polypropylene capacitors using a simple, say, high-pass filter. When corrected for differences in capacitance (there will be small variances in overall capacitance which could bias some tests), it seems very unlikely to me that differences are audible. But who can say without the data?

[pedroskova]

Steve Bench showed electrical differences between different cap constructions on an O-scope -- his site is archived somewhere on the web.

[Jonathan Bright]

Many years ago when "AudioXpress" was just a monochrome "Audio Amateur" there were CRO results published. Cyril Bateman in "Electronics and Wireless World" UK did harmonic distortion measurements a few years ago. (Magazine now may be called by another name.....) The same mag published work on the effects of the mechanical changes in the dialectric and how that might change the results. That was more recent. "Audio" also published distortion results for ceramic caps, I think. That would be 30 yrs old now.
But what is more interesting is the dynamic effects that are harder (or impossible) to see in steady state results.
There is a decisive result in this country (Australia) of how a large polyester cap had a quite distinct "memory" of a previous charge appear after the operators had assumed it had been fully discharged. Can't quote chapter and verse off hand. But it is that sort of quality that makes some of us suspect that we are hearing a "smearing" or other change when comparing caps of different types.
I know some of the terminology is a bit vague but I am committed to serious hard science and that when we know what to look for and how to measure it appropriately then things will appear more rigorous.

[dantheman]

Check this out as well:
http://www.classicspeakerpages.net/I...e=post&id=5415

Badman, have you read the AES article? If so, could you summarize it a bit?

Thanks,

Dan

[Curmudgeon]

The classics:
http://waltjung.org/PDFs/A_RealTime_...or_Quality.pdf

http://waltjung.org/PDFs/Picking_Capacitors_1.pdf

http://waltjung.org/PDFs/Picking_Capacitors_2.pdf

I realize with surprise that I am very weary of such posts and discussions. I guess I'm coming to feel:
Try it yourself, with some moderately highly recommended types, and some with bad reviews, in the crossover prototype. Use good assembly practice, good solder joints, star ground, etc., installing all the "good" and then all the "bad" caps; or just build two prototypes. If you hear a difference, it exists, if not it doesn't. If you're not willing to try it yourself, then the (no doubt unworthy) suspicion of trolling is raised.

[PeteMcK]

buy a couple of pairs of caps and a switch.....

[Pano]

There was a rather good article with great measurements of caps posted on here a little while ago. Will see if I can find it.

Also check out the polypro vs ceramic files in the demo downloads of Audio DiffMaker. Both are compared to a piece of wire.
Audio DiffMaker