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rtate 1st August 2009 07:00 PM

Capacitor coupling question...
 
I have a Marantz 2230 receiver that is cap coupled.
I am going to replace the electrolytic coupling caps with new pieces.
The original value is 2200uf 63v.

What are the benefits to be had by increasing or decreasing the value of these caps??

i.e. more bass etc.

Thanks

Conrad Hoffman 2nd August 2009 12:29 AM

Don't know where they are in the circuit, but generally too small and you lose bass, though it may sound tighter. Too large and the charge time might result in thumps, some kind of instability or even circuit damage. IMO, the risks of that are low.

nigelwright7557 2nd August 2009 12:45 AM

The designer will have chosen 2200uF for various reasons.
Cost, performance and size amongst others.

Personally I think I would leave it as it is.
Just replace it with a good quality component.

Cliff45 2nd August 2009 02:10 AM

I'll add just a little bit here, make sure that you get some GOOD quality capacitors for this unit! You don't need to go crazy or anything, audiophile-grade units would cost a fortune here and, IMO, would not add enough perceived difference in sound quality to justify the expense.

If these are in the audio signal path, I would take a look at the Nichicon "Muse" FW line of audio grade electrolytics, they have gotten some praise from folks and won't drain your wallet too much for this size/voltage component. There's a 2200uF/63V component in this series, I think.

This will more than likely have a significant upgrade to the sound quality for this unit anyways, since there were originally made in the 1970's, correct? Any electrolytic that is that old should be replaced anyway, and there's probably a lot of other ones inside that are performing marginally at this point, too.

I found a website that has a lot of documents for this particular unit, plus schematic scans located at: http://www.jmargolin.com/marantz/marantz.htm

I like these old Marantz recievers, very easy to service and built well, too! :D

-HTH

rtate 2nd August 2009 02:42 AM

Cliff45, those are the exact caps that I have on my bench!!
I just thought that if I bumped them up to say 4700uf I might make some SQ improvement as I have lots of room...

Cliff45 2nd August 2009 03:12 AM

Quote:

Originally posted by rtate
Cliff45, those are the exact caps that I have on my bench!!
I just thought that if I bumped them up to say 4700uf I might make some SQ improvement as I have lots of room...

Ahhh, so you already knew about Nichicon.... :D

As far as changing the values of the caps, I would have to agree with what Conrad said in his post. Better to just replace the factory ones with the same value, it's BOUND to improve the bass just having new, high-grade caps in there anyways!

Perhaps there are some dried up, out-of-spec electrolytics in the power supply of this little gem that could use some freshening up, too? Or is this post just related to the last couple of things you have to do before you fire it up after totally going through it? :cool:

I hope it sounds better than you remember it did, that always makes thinks worth the effort in the end!

rtate 2nd August 2009 03:38 PM

I plan on doing a complete refurb, I've already replaced the lamps with Don's leds, new vellum paper and a really good cleaning.

As for the coupling caps the new hi grade caps are alot smaller than the originals and I did kind of want to keep it stock looking..

I will be replacing as many of the electrolytics as I can in the power supply and amps section( I'm not sure about the FM section though??)

and I'm also looking for the wood case for it as well...:D

RocketScientist 2nd August 2009 06:47 PM

Caps of that value would either be the main power supply caps or the output caps to the speakers in an old single rail design. In either case going larger in value is probably safe and may even yield some improvements.

The plus to larger output caps is lower frequency bass cut off and less low frequency distortion. The downside going larger with the output caps is a larger "thump" at turn on (if it doesn't have a delayed speaker relay).

The plus to bigger power supply caps is more power reserve and less ripple at high power levels. The downside with bigger power supply caps is it puts slightly more stress on the bridge rectifier and makes for higher peak currents which increases the EMI (i.e. hum) pickup from the power supply. It will also increase the turn on surge from the AC line.

In either case, I'd suggest bypassing them with some 0.1uf film caps (ideally polypro like an MKP) of sufficient voltage in parallel.

nigelwright7557 2nd August 2009 08:08 PM

Quote:

Originally posted by RocketScientist


The plus to bigger power supply caps is more power reserve and less ripple at high power levels.
It also gives a higher power on surge current which can possibly blow the mains fuse.
I increased the power supply caps on an amp of mine and it immediately blew the 5amp mains fuse.
Clearly you can fit a higher ampage fuse but then you can lose some protection.

RocketScientist 2nd August 2009 08:28 PM

Quote:

Originally posted by nigelwright7557


It also gives a higher power on surge current which can possibly blow the mains fuse.
I increased the power supply caps on an amp of mine and it immediately blew the 5amp mains fuse.
Clearly you can fit a higher ampage fuse but then you can lose some protection.

Yeah, I went on to say just that in that same paragraph. Normally it's not a problem but it depends on how *much* bigger you size the caps. In this case, 2200uf is fairly small to begin with, so even a 4700uf won't present much surge current at turn on. But, from the description, it sounds like the caps being upgraded are for the output. They also have to be charged at power up, but do so more gradually and to only half the supply voltage so the power fuse is in no danger.


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