Acoustic 150B caps

[sturoc]

I recently purchased this much adored 1970 Acoustic bass amp.
There are few caps that actually have separated ends, seepage etc.

Being electrolytics at 100uf 50v & 10uf 50v so on and so on.
of course in this modern time i cannot find the exact replacement style
The uf and voltage I can find, but they are are smaller, some alot smaller

Will these exact match value/voltage new replacements be good to use even though they smaller ?

[leydenjar]

Yes. They're the same ratings.

You may want to go a little higher on the voltage rating. For safety.

[sturoc]

Yes. They're the same ratings.

You may want to go a little higher on the voltage rating. For safety.

SO I can fudge the voltage higher with no affect on sound quality, etc ?

I know that the guys at the old Acoustic knew what they were doing when they designed these circuits.
But if there's a valid modern reason to increase volt rating, bring it on.

thanks

[Enzo]

In the last 40 years, cap technology has advanced along with everything else. Materials are better, so caps no longer NEED to be the size of beercans. Smaller is just fine - it is the specs that matter, not the dimensions.

There is no reason in the world why 63v caps won;t sound exactly the same as 50v caps, all else being equal. If the 50v cap is in a 12v circuit, then sure, the extra voltage probably won't make anything safer. On the other hand of teh circuit is running at 48v, then maybe some extra room is advisable. 40 years ago, caps were a much larger portion of the cost of something than they are now. So keeping them as minimal as possible saved the factory money.

[sturoc]

Excellent observation / explanation
Thanks very much !

[Rick Erickson]

[I know that the guys at the old Acoustic knew what they were doing when they designed these circuits.]

You are giving them a lot of credit. They made engineering & production mistakes just like most every other manufacturer. As one of their warranty techs in the mid '70's I got to deal with most of them. The 150 series was a pretty good design. The had some issues with pc board connectors - the cure was to remove them and solder the wires direct to the boards. They also had a problem with the power resistors on the power amp board overheating and melting their solder. Years later their chief engineer would develop a line of amps under his own name that were famous for the low voltage supply resistors running so hot that they melted their solder connections...

RE