Capacitor Upgrade

[jjohnson]

I preface this post by saying that I know very little about the inner workings of electonics. I own a pair of Magnepan SMG-a and would like to replace the capacitors. They are 20 years old and known to be of less than stellar quality in the first place. The question that I have relates to values. The current capacitor is rated for 50mF and 100 volts. I have no difficulty finding 50mF capacitors but most are rated for 250 volts or 500 volts. I can find very few rated for 100 volts. What would be the impact of a cap rated at a higher voltage?
Thanks in advance.
Jeff

 

[udors]

Just recapped my first pair of Large Advents. Same what I thought was a problem. After getting good advice on this board (similar question) I replaced the 50V electrolytes with 400 V Poly caps. The speakers sound great.

 

[Paratima]

udors is correct. As long as the capacitance is close (right on is best), the working voltage of any modern cap should be fine.
For your reading pleasure and further edification, try the Speaker Forum Reference Threads.

 

[ericj]

Going up in voltage, especially with films, isn't a problem.

Going down can be. But it's unlikely that most speakers will ever see more than 50 volts. Not for long enough to hurt the cap anyway.

So the rule is same or higher voltage, and as close as you can get on the capacitance. Paralleling multiple caps to get where you're going is totally acceptable, too, but it helps if you have a capacitance meter for matching purposes.

btw, "as close as you can get" gets subjective sometimes. for example some ADS speakers might have a 6.8uf or 7uf cap, or a 5uf or 4.7uf cap, depending on the year it was made. I suspect that there were no changes in the drivers, and the caps were just close enough.

 

[udors]

Capacitance

Any opinions on whether to go up or down on capacitance? Redoing a pair of Electro-Voice. The original cap is a 4.5mF electrolyte. Want to replace them with Polys, but finding them listed at either 4.3mF or 4.7mF. Up or down? Close enough either way?

 

[Wayne1]

Capacitors do add together very well.

It would do no harm to get a 4.3uF and a 0.22uf and put them together.

Most electrolytics are lucky to hit + - 20% of their spec.

Film caps are 5 % at worst case.

 

[jjohnson]

Is there a readily available brand (say at Madisound or Parts Express) that anyone could recommend for a price/sound quality value?

 

[Zilch]

3.0 + 1.5 in parallel = 4.5 uF

Daytons or Bennics are fine.... :yes:

 

[Harvey/ Ga]

Is there a readily available brand (say at Madisound or Parts Express) that anyone could recommend for a price/sound quality value?

I've used dayton 5% from Parts Express on my Wharfedales and Smaller Advents. The Advent 5012/W's that I bought on E-bay also had them installed, by a latent AKer :thmbsp:

 

[trondareo]

Visit the magnepan users group over at the Planar Speaker Asylum.
http://db.AudioAsylum.com/cgi/search.mpl?forum=MUG&searchtext=SMGa+capacitor