Blown cap in speaker..

tvtech said:

Hi Bounty

The OP is probably looking at a "cheap way" to accomplish a speaker crossover repair. I know there are better more expensive options....let him learn in the meantime

Get him up to speed with the very basics first though..what say you pal

Regards,
tv tech

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Maybe. I like to fix things just once. The cap that blew out failed because it was a cheap component. The nice thing about film type caps is they are "self healing" to an extent. When punched through with overvoltage, a small section area of the cap gets taken out but the cap remains functional. We used metal poly caps by the dozens in high voltage/high current applications in switching power supplies. In 20 years, I can't remember ever seeing one fail. As for how many electrolytics failed: a number too high to even try to count.

bountyhunter said:

Good quality crossovers use poly caps, NP elevtrolytics are crap and have poor frequency response. Poly caps do cost more but you get what you pay for.

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Nice theory - rather falls down when most of the best sounding speakers ever made used NP electrolytics.

However, back to the original reason - it's VERY, VERY rare for NP electrolytics to fail in crossovers, I can only perhaps remember changing one in over 40 years as a professional service engineer?. Far more common problems are the bass units and treble units.

i've replaced tons od electrolytics in crossovers. usually a shorted speaker as well. the problem here being not the design of the crossover or speaker, but sales staff not knowing the power handling capability of the speakers they sell, so they sell 100 watt speakers with a 250W/ch receiver. the first time the customer has a big party, i get what's left of his speakers in for repair, with blown drivers AND fried caps in the crossover.... even had one recently where the ceramic resistors in the crossover caught the speaker stuffing on fire...

Nigel Goodwin said:

Nice theory - rather falls down when most of the best sounding speakers ever made used NP electrolytics.

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Like the way you post unsupported opinions as universal laws.

I have built crossovers and the speakers they go in, and I own some of the "best sounding speakers ever made" (Infinity) and they don't use electrolytics in signal path applications. Neither does anybody else who knows anything about sound.

Electrolytic capacitors for audio purposes

The reputation of the electrolytic capacitors is not flattering.
They are accused to be the worst component causing distortions
in any circuit of a high-end audio network. It doesn't matter if
the good old electrolytic capacitor is sitting as a quick power source
in the power supply or as a coupling capacitor in the pre- or power
amplifier or in the crossover filter of a speaker system, they just
destroy the whole thing.

They have a high dielectric absorption causing serious
phase(frequency) delays. Signals going through electrolytics
are slowed down and suffer severe harmonic distortion.
They have high impedance and ESL value at higher frequencies and
their resonance frequency is too low to be used in a wide band
amplifier. Most of the accusations are true, but then everybody knows that the electrolytics are indispensable because of their unbeatable C/V ratio.

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bountyhunter said:

Like the way you post unsupported opinions as universal laws.

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I like the way you keep posting the same irrelevant clip about electrolytics

Although I'm somewhat bemused why you would disagree that most of the worlds best sounding speakers have used NP electrolytics in them? - as have many of the worlds best sounding amplifiers.

I have built crossovers and the speakers they go in, and I own some of the "best sounding speakers ever made" (Infinity) and they don't use electrolytics in signal path applications. Neither does anybody else who knows anything about sound.

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Obviously you know much more about it than the best manufacturers, we all bow down to your superior knowledge.

All my half-decent speakers have pretty good quality and accurate value poly capacitors in the crossover network.

All 3 of my TVs have "obsolete" CRTs and they work perfectly.

electrolytics, with proper construction and electrolyte formulation, do NOT exhibit the characteristics you are saying they do. yes, there are gazillions of garbage caps on the market, poorly constructed and formulated. but i've seen panasonic , nichicon, and other well made caps, not only work well in audio equipment (onkyo exclusively uses nichicons, in the signal path), but continue working well for many years. they also work well in many crossovers, as long as they are used properly. on the other hand, i HAVE seen poly caps fail miserably in crossovers when their ratings are exceeded (just as an electrolytic would fail, but the poly caps can catch fire when they fail).

if you want my opinion about speaker "brands", i would actually place infinity on the mid-scale of speaker manufacturers. and that's not just cost and materials related, but for audio quality as well. the real difference in the quality of a crossover is not necessarily the caps, but the inductor construction. most pro-audio speakers and well made home audio speakers use air-core coils, because air doesn't saturate, while iron and ferrite do. of course this requires a lot more copper.

This is simple, I would replace it with what ever is in the other speaker. If you up grade one than up grade the other.

Yeah, electrolytics are great. I just wish I had a dollar for every one I have had to replace because it failed.

https://www.electro-tech-online.com/custompdfs/2012/06/reliability_of_capacitors.pdf

Aluminum Electrolytic Capacitors Reliability

In aluminum electrolytic capacitors as they are used the capacitors slowly degrade over time and once a capacitor has degraded beyond a specified amount the capacitor is considered to be a failure. Most capacitors are considered a failure when the capacitance has changed by 20 to 25% of its initial value.

Aluminum electrolytic Capacitors load life’s ratings are generally expressed between 1000 and 10000 hours

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i HAVE seen poly caps fail miserably in crossovers when their ratings are exceeded

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?????

So if you stress the part beyond it's ratings it will fail so that means they are no good?

OK, whatever.

Go ahead and use the ones with the built in failure mode that degrade over time. Technicians have to put their kids through college.

How to do it

The guy got 10 x 10µF 100V electrolytics (polarized) and need to make 1 x 15µF (non polarized), right ?
Then make 3 x 5µ in parallel (each 5µF is 10µF + 10µF in series, joined by the minus pole)
Not very neat but will work with what is available.
Cheers
Benoit

So if you stress the part beyond it's ratings it will fail so that means they are no good?

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i did say "if their ratings were exceeded", meaning that somebody ran the speaker well over full power.... you can try to make things idiot proof, but idiots can be so darned clever....