Cheap Caps?

[marob]

Yo!

How much does the quality of a cap affect sound? For instance, if I bought some caps from Radio Shack, are they decent or crap?

I installed some caps from Radio Shack in a couple of cone tweeters and I am getting some crackle at certain frequencies. The tweeters are putting out lots of highs, just some lower highs crackle a tiny bit.
Is there any chance it's the caps, or is it the speakers?

If I remember right, the cutoff of the caps is 5000hz and the tweeters go down to 4000hz.

Thanks for the help.

~Matt

btw, first post!

[Sch3mat1c]

Well, mentioning "RadioShank" and "caps" in the same sentence is probably going to get your butt flamed (as your butt already deserves from what your sig does with it ), they don't sell any mylar caps that size so it'd have to be electrolytic (nonpolarized). It's bad enough that they're nonlinear, but worse that they are used in a situation where that nonlinearity will actually show itself.

All in all, I doubt that the capacitor is what you're hearing, unless it is indeed very faulty. The most likely distortion product would be odd order, the first being the 3rd harmonic at, at lowest, 15kHz - barely audible. The fifth at 25kHz is inaudible period. I would suspect your speakers, since they can produce much more unusual responses (rubbing, buzzing, resonances and whatnot that may have nothing to do with the tone sent at all, as opposed to electrical harmonics which are always a multiple of the fundamental frequency).

Tim

P.S. Hmm... you anywhere near southern WI like me?

[audiousername]

Welcome

Is this a first order crossover? (If so, it will be a single cap in series with the tweeter of around 4µF assuming tweeter impedance of 8W). If it is, it may be possible, though I'm not sure how likely, that the tweeter is running out of excursion because it's been called on to produce some lower frequencies - you're only 12dB down at 1.25kHz and 18dB down at 625Hz.

Either that, or some other rubbing, buzzing, resonance etc that Tim has already suggested. I wouldn't think it would be the capacitor, but they should be cheap enough that you could change it anyway to see if it was to allay any fears

[marob]

Yes, it is first order. Yes, it is a 4.7µF electrolytic. So I guess thats probably the problem, though I'm still not sure what the frequency response of the tweeter is. Or it could be that I paid $7 for both speakers (did I forget to mention that?).

It's bad enough that they're nonlinear, but worse that they are used in a situation where that nonlinearity will actually show itself.

Should I not use electrolytic caps period, or am I just using them wrong?

Anyway, thanks for the help.

~Matt

PS. La Crosse, originally from East Troy though. Nice sig, btw.

[AndrewT]

Hi,
you need bipolar electrolytic for speaker use.
If you go plastic film the caps will cost more than the speakers.
But then you will get the best out of them. You will probably find that they need some equalising and maybe a 2 pole xover. The costs are mounting.

[DragonMaster]

What are they, CTS piezos? Get older Motorola if so, and try to find app. notes articles for them, they use things like a parallel 100Ohm resistor if I remember correctly.