Help with caps for API 550A Eq.

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API

Well-known member
Joined
Nov 25, 2005
Messages
869
Location
Sweden
Hi.
I am currently recapping my API 550A eq´s and have a few questions.
In the original schematic the filtering caps for the power rails (+ - 16v) are 10/25v, but in a later schematic i have wich is dated ca 1980 these have been upgraded to 100/35v.
Is it just a question of size/value (caps getting smaller/ratings higher), that they would have used 100/35v from the beginning if they could have fitted them?
Also, in the later 554 eq schematic they also have the 100/35v caps in this place.
Should i use the higher value here??

Then there is a small 0,47 electrolytic in there.
Could not find that value in the Panasonic caps i use, but found another one that was non-polarized.
Would this be ok as a substitute?
Any advantages/disadvantages to use non-polarized caps??

And last the output cap (500/6,3v vs 470/16v).
Again this have different power ratings in the different schematics.
6,3v in the early and 16v in the later.
Would there be any audible difference??
I guess not, but i thought i would ask.

Regards,
Dennis
 
[quote author="API"]would have used 100/35v from the beginning if they could have fitted them?[/quote]

maybe. I dont think it matters either way. The ESR makes more difference than the value. Id use a panasonic FC 100u, because I have them on hand.

[quote author="API"]
Any advantages/disadvantages to use non-polarized caps??
[/quote]
maybe. A nonpolar cap might last longer if it has alot of AC current flowing thru it. it will likely be twice as big as a polarized cap, and probably only available in a radial package. probably no detectable difference in sound. maybe if you recapped a big console with 100s of them in series, but I wouldn't personally say either is better.

[quote author="API"]
And last the output cap (500/6,3v vs 470/16v).
Again this have different power ratings in the different schematics.
6,3v in the early and 16v in the later.
Would there be any audible difference??
[/quote]

audible? nah. but all other things being equal, the higher voltage cap will probably last a little longer in this position. especially if the output is always patched into a low-z input and passing high levels. or maybe put a nonpolar cap here if you want to get fancy. personally I wouldnt bother. 470/16 or 470/25 if it will fit.

mike
 
Hi.

Thanks for the input.
I have now ordered the parts and will start to recap soon!

Regards,
Dennis
 
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