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Replacement capacitors exploding

I replaced the capacitors in the crossovers in my Klipsch KSM-1 stage monitors.
There is a capacitor that runs parallel to the woofer which had blown in a couple of my dozen stage monitors. They are from the 90s, which is not ancient, but I figured maybe that age is a factor so I swapped them all out.

The replacement capacitors have all of the same numbers printed on them but are a fraction of the physical size, and in just one season almost all of them have blown. I don’t think they were being pushed harder.

Is there a way for me to order capacitors with the same specs printed on them that are also heavier duty in some other way?
jamesheyser

Showing 3 responses by cakyol

cakyol's avatar
cakyol
940 posts
 

For best performance and long term reliability, crossover caps MUST be NON polar FILM capacitors PERIOD.

You should NEVER use electrolytic capacitors for that purpose (well, they may be kludged back to back but forget it). Furthermore, you should pick ones with the highest voltage rating that you can find, since they are subject to AC voltages in the crossover. You can NEVER go wrong with higher voltage ratings. Buy the HIGHEST voltage rated version that you can find. They will be more expensive, but you will sleep better.

If you have accidentally used electrolytics, they will blow almost immediately.

Here are some excellent examples:

https://www.partsconnexion.com/Jantzen-film-caps.html

The silver ones are rated up to 1200 VDC, which is probably ok for about  up to 300VAC, which is more than any power amplifier can ever put out and they will outlast your house.


cakyol's avatar
cakyol
940 posts
 
@imhififan

Although what you say works, the electrolytics will not have the lifetime of film capacitors. Their lifetime is in the 5-10,000 hours range at best, whereas the film capacitors' lifetimes are typically in the 50,000 hours range.

Please get film capacitors :-)

Also note that if the capacitors you buy are rated at a specific DC voltage, they will only be able to withstand about a third (theoretically about half (square root of 2) but I am being conservative) when exposed to AC voltage, which is what is inside the speaker.  So, get a film capacitor with highest possible voltage you can find.

If you have a 500 watt 8 ohm amp, the peak voltage across the capacitor may be up to 65 volts AC and may shoot up to 100 volts (approx power supply rail) during very heavy transients.  So, you would need a MINIMUM 300 V DC capacitor.  The higher the voltage rating, the less stressed it will be, which all adds up to longevity & reliability.

If you want to sleep better and not worry, pls do the above :-)



cakyol's avatar
cakyol
940 posts
 
@fiesta75

Here are some EXCELLENT high end film capacitors. There are PLENTY of them:

https://www.partsconnexion.com/film-capacitors.html

Some are RIDICULOUSLY priced but some categories of Mundorf, Solen and Jantzen are of excellent quality and very affordable.

Remember... get the HIGHEST voltage rated ones that you can find for the same capacitance value.

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