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-   -   Series capacitors in crossover (http://www.diyaudio.com/forums/multi-way/220014-series-capacitors-crossover.html)

Calamaro 19th September 2012 12:25 PM

Series capacitors in crossover
 
1 Attachment(s)
I want to recap my old Videoton Minimax crossovers.
They have two 10uf polar axial electrolitics in series like in the picture (+--+): can I use either a simple 5uf bipolar (4,7uf is easier to find) or two general polar electrolitics like these??
10 condensateurs 10uF 35V Nichicon VX axial | eBay

Pano 19th September 2012 12:41 PM

Yes, that should work.

wintermute 19th September 2012 12:46 PM

5uF bipolar should be fine. 4.7 would be within 10% of the nominal 5uF so should be ok as well provided they didn't hand pick the caps for tolerance.

You could use two 10uF but the ones you linked to a too low a voltage. I'd not go lower than the original 100V caps.

Tony.

Pano 19th September 2012 12:47 PM

Doesn't that give 200V in series?

Calamaro 19th September 2012 12:50 PM

Yes I think so. Isn't too high for a speaker crossover?
Don't 35v (actually 70v if in series) could be enough?

wintermute 19th September 2012 01:09 PM

yes you are right series electros the voltage doubles... I've always used the rule of thumb that 100V was the minimum rating for crossover caps, mainly because of jaycars site (example http://www.jaycar.com.au/productView.asp?ID=RY6904 ) where they state that their 50V bipolars are not high enough voltage for crossovers and 100V bipolars should be used. So even at 70V they didn't come up to my minimum rule of thumb value ;)

Tony.

Bare 19th September 2012 04:16 PM

Real question is: why are you being so "frugal" that you wouldn't be substituting even a cheap Film 'n Foil cap instead of the Electros??

Calamaro 19th September 2012 04:58 PM

Sorry but dielectric isn't that important at the moment, just trying to understand which capacity I have to use. I have some nice 4,7uf Arcotronic polyprop in my parts bin, but this time I'll probably end with a respectful restoration.

sreten 19th September 2012 11:45 PM

Hi,

the Jaycar statement is pure nonsense, unless your talking PA stuff.

50V is good for up to 100W, 100V is needed for up to 400W.

50V is plenty for Minimax's, and a bipolar is a much better idea than
than two polars back to back usually, as a bipolar must be for audio.

rgds, sreten.

wintermute 20th September 2012 09:12 AM

It could be due to the kit amps that have been sold over the years here in Aus. Generally speaking they have often been over 100W / channel into 8 ohms, with 150W or 200W / channel into 8 ohms not being unusual.

I'm not suggesting that people actually need that amount of power, or that they would be using it, but from a point of view of selling something I guess sizing the product to not fail in worst case scenario makes some degree of sense :)

Thanks for setting me straight on it. As I said I always used it as a rule of thumb, I'd never tried to do any calculations to work out the actual power that a particular cap could withstand.

Tony.


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