Replacing electrolytic caps in crossovers - what voltage rating to use?

[Ruach]

Hi guys,

I am replacing the 17-year old electrolytic capacitors in the crossovers of my Infinity Kappa 7 speakers.

These capacitors are rated at 100V.

Will it be ok if I were to use 63V or 50V capacitors as their replacement?

I am thinking of using Elna Silmics as replacements. 100uF Solens are too big and too expensive for me right now.

Appreciate your help. Thanks.

 

[simon5]

What's the impedance of the speakers and what's the power level you're playing with?

It would be way better to use 100V caps. You can make a 100V cap by using 4 of the 50V caps in series-parallel.

 

[Ruach]

Thanks.

The impedence is between 4 to 6 ohms.

How do you go about getting a 100V out of 50V caps?

Do you connect - + + - ?

 

[simon5]

Let say you have a 100uf 100V cap.

With two 100uf 50V caps, - + + - will give you a 50uf 100V cap.
Then you parallel that with another pair to get back at 100uf.

What is the maximum power you plan to use with these speakers?

 

[alfa147]

you can use 63v 100mf capasitors.it is not problem with hi-fi amplifiers.But be careful about polarity.

 

[rabbitz]

You are better off giving the eletrolytics the flick and using metallised polypopylene and even the ones cheaper than the Solens would be better than the original.

 

[d'yermak'er]

caps value

So an 18uf + another 18uf dosn't =36uf unless you double that again?

 

[Tom4s]

Sorry to resurrect a thread from the mummies, but Google led me here... I have a pair of Infinity Q3 with dual voice coil Watkins. I am therefore thinking of replacing four 600uF caps that are connected in series with chokes and the woofer coils. I like to play loud, and I now have the Hypex nc500 amp from diyaudio user Boggit. It can peak at about half a kilowatt. These speakers can dip to 2 Ohms, as the voice coils are paralleled. I can see no voltage rating on the old caps. They are original (circa 1978).... What do I replace them with?

 

[Tom4s]

I see 600uF caps intended for microwave ovens that are cheap...

 

[eriksquires]

If you must go with electrolytic stick with bipolar. Bypass with 1-5% in a film cap. Bennix, Axon or cornel dubilier are good low cost bypass caps for this. Axon is low cost Solen rebrand

 

[Tom4s]

At 600uF times four, yes anything but electrolytics will be excessively expensive, and I anyway gather that the quality of woofer caps isn't all that critical. Would you agree?

The bypass is interesting. Do you mean to parallel the bipolar electrolytic cap with a film cap of something like 10 or 22 uF? And why is that good?

 

[Tom4s]

Main question is: what voltage rating do I need?

 

[Lojzek]

No, the real question that matters is how much voltage can you send
to speakers without destroying these?

You think bypassing with smaller caps makes sense? Can you bypass
a VW Beetle with a Porsche sticker and say that it's now a sports car?

 

[woody]

You may look at this article it has a little bit about why a bypass cap is sometimes a good idea. http://waltjung.org/PDFs/Picking_Capacitors_1.pdf

 

[woody]

Just for the heck of it I looked at Walmart online. I know NOTHING about these but they do look interesting and rather cheap !


Metallized Polypropylene Film 600uF AC 250V Motor Starting Capacitor - Walmart.com

 

[SY]

You might consider that if you use a high voltage cap, the most likely failure point is then the driver. Caps are cheap, drivers are not.

Bypassing a woofer cap is harmless but doesn't have much actual function.

 

[system7]

Amazing how people don't do simple homework.

Infinity Quantum Serie

I'd lose the 600uF in the Infinity QLS 3 altogether. They hardly do anything. Kappa 7 schematic follows.

Quite alarming 2 ohm impedance from the dual-voicecoil woofer. You wonder why separate filters were used on each voice-coil, which must sum to something simpler. Who designs this stuff? LOL

 

[AndrewT]

Sorry to resurrect a thread from the mummies, but Google led me here... I have a pair of Infinity Q3 with dual voice coil Watkins. I am therefore thinking of replacing four 600uF caps that are connected in series with chokes and the woofer coils. I like to play loud, and I now have the Hypex nc500 amp from diyaudio user Boggit. It can peak at about half a kilowatt. These speakers can dip to 2 Ohms, as the voice coils are paralleled. I can see no voltage rating on the old caps. They are original (circa 1978).... What do I replace them with?

half a kilowatt into 4ohms is roughly 63Vpk. Allowing for a worst case output voltage peak of 70Vpk then I'd suggest the absolute lowest voltage bi-polar or non polar capacitor you can use is 80V. But I suspect you can more easily source 100V bi-polars, if you need them at all !

 

[system7]

It's gotta be 100V Non-polars in a speaker that goes so loud.

I usually go by the power rails on the amp. A 20W pc amp has a +/- 30V power supply. Assuming you don't have high-Q resonant LCR circuits which multiply voltage.

A more powerful amp can output much higher voltages.

 

[AndrewT]

It's gotta be 100V Non-polars in a speaker that goes so loud................

100V, 600uF plastic film (MKT) will be mighty big and mighty expensive if one cannot locate a special offer.