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uncommon cap value

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5/20/2000 3:12 AM
JC	uncommon cap value I need a 32+32uF 450/500V electrolytic cap, but it has been impossible o find one. So I think I could "reproduce" it with two separate caps, but I can't find that value neigther. Closest thing I found was two 22uF 450V. They are for filtering the current. Are they allright, or should I go for 47uF 450V ? Thanks. JC

5/20/2000 11:39 AM
Brad	JC, Safer to go higher (as close as possible) in capacitance and voltage, than lower. If you're SURE the circuit with the 500V cap can run with 450V cap, that should be OK. Brad

5/20/2000 1:17 PM

You could use an LCR can cap 50 + 50 @ 500 volts. My buddy uses them in his Marshalls. I put them in my Traynor YABA1 Bassmaster, which originally I believe had 40 uf's. Might give you more bottom and more punch to the sound. You can get them from New Sensor, maybe Antique Electronics? Otherwise you can get a couple of 80 uf @ 350 volts and put them in series, but they'll take more room to install. Antique should have those as well as Angela Instruments and other places.

Good luck, T.B.

5/20/2000 3:03 PM
JC	Thanks, Brad, thanks, T.B. It's working apparently well with those 22uF which were what I had on hand. (Everything closed on saturday, BTW, so they "had" to go in there.) JC nb: I've seen an amp (mine) with them in series and in the middle, a resistor connected to ground. Don't know why, do you know? More bottom?

5/20/2000 6:03 PM

quote:
"nb: I've seen an amp (mine) with them in series and in the middle, a resistor connected to ground. Don't know why, do you know?
More bottom?
"

usually there is a resistor (both having the same value) in parallel with each of the two series caps to equalize or balance the voltage evenly across the two seriesed caps. Nothing to do with increasing bottom.
jason

5/20/2000 10:09 PM
JC	===usually there is a resistor (both having the same value) in parallel with each of the two series caps to equalize or balance the voltage evenly across the two seriesed caps. That's exactly my case. Thank you for the explanation, it seams obvious, but I didn't realize which was the purpose for those resistors. JC

5/23/2000 7:02 PM
J Epstein	Also the two resistors taken together act as a "bleeder" for the B+, keeping the caps from maintaining their charge when the amp is powered down, a little free safety benefit. But primarily they are there to maintain an equal voltage across each cap even if the caps are somewhat mismatched in capacitance. -j

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