CapacitorsReplacing the old with the new. What is acceptable?

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I am faced with replacing some old power smoothing capacitors in a Marantz Model 15 power amplifier, the problem is that the caps are 5450uf@ 50v. The vendor I have contacted has stated that using a 7200uf cap@50v is ok, is this true? safe? as I am doubtful. Also I am looking for two values in axial format 350uf@50v, and 250uf @80v, are there any audiophile grade caps out there? Thanks everyone for your views and help/opinions. Jeff
 
I'm not so knowledgeable about the Marantz model, but the specs you quote for the replacement part seem ok. As for the "audiophile" grade, I would not worry too much about it, these values are big so they are EDIT: NOT likely to be in the signal path. You can go for above regular brands and will probably get good results.

Sébastien
 
Small difference in uF (capacitance) is not a problem (in this situation), just keep 50V as the minimum.

Audiophile caps, why it has to be axial? Black Gate is considered audiphile caps IMHO and the standard version has 220uF/50v and 330/50v (the difference must be ok). AFAIK they don't produce the standard version anymore, so you may get them at cheap, or you can hardly find them.
 
capacitors.............

I thank everyone who has taken the time to read and also reply to my post; I have in fact taken into consideration the use of a 63v cap as a replacement however the question remains-when going up in uf what is considered safe/wise given the existing equipment(stock). The Marantz equipment is very high performance ( model 15-/model 7t ) and the cap therefore has to be audiophile grade. No matter where inside the amplifier a change of any kind is audible given the euipment. I am primarily concerned that going to a 7200uf cap@50v is perhaps dangerous to the rest of the amp given the original being 5450uf@50v. How high can you go witht he solid stae? Thank You! Jeff
 
If I am not mistaken, Marantz's Model 15 was an amazing design for its day - particularly the output stage. I haven't tried to tweak one, but analyzing the design concepts, I suspect that with some judicious component replacements and alterations of operating points, it could be made to sound quite nice indeed. An underrated design that is well worth taking care of, IMHO.

hth, jonathan carr
 
My version of it all:

A capacitor sitting in a power supply - as in your situation - can be looked at from two "directions": one looking toward the amplifier itself and the other looking toward diode bridge and
transformer.

Toward the amplifier: There is only one rule: The max. voltage for the capacitor must be higher than the voltage needed for the amplifier. The amplifier does not care about the amount of farads in any way.

Toward the diode bridge and transformer: This is more tricky because of the amount of current there will rush in when turned on. Once it's turned on everything will "quiet down" and there will only run a small amount of current.

Therefore the size of the bridge and the transformer is more important than the electronics of your amplifier.

So I conclude, that you have no reason to be scared of anything, as long you don't overdo it. Going from 5000 to 7000 is not that much of an issue. And I believe that you will get better sound out of it. Simply there will be more current available when needed.

And go for the capacitors with low ESR.
 
Toward the diode bridge and transformer: This is more tricky because of the amount of current there will rush in when turned on. Once it's turned on everything will "quiet down" and there will only run a small amount of current.

Half true. Inrush current is indeed a big consideration, in fact, normally the biggest. But once everything has settled down, you still have to consider max charging current. Ultra-big caps with low DCR transformers can spell death to rectifiers. I learned this the hard way.

That said, going up 50-60% in capacitance won't hurt anything and, as John said, can only be a benefit.
 
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