Info on shunt caps for Adcom GFA-545?

nadams

Can I do the shunt cap mod on my GFA-545? If so, what type of caps do I need? I'm very familiar with capacitors on computer motherboards, as I've replaced scores of bad ones. Audio caps, on the other hand, baffle me.

See here for pics of a 555 with shunt caps installed - http://www.polkaudio.com/forums/showthread.php?t=76378

Thanks in advance,

Noah

ben62670

You can easily do the mod. All you need is some 100v or better film caps like you would use in an XO. Now what values you use are controversial. I like either 12uf, or a combo of 20uf, and 1uf paralleled. I will be doing this mod soon. I had a 555 with the mod. I take a look at the schematic to see if there are any input caps that should be replaced. Shoot me a PM if I don't post an answer by this evening.
Ben

nadams

So then, I'm looking for something like this, right? - http://www.parts-express.com/pe/showdetl.cfm?Partnumber=027-430

Would I need 2 or 4?

fredv

4, one by pass per main filer cap.
I did this before I shipped my pair of GFA-555's the new happy owner.
This is a low cost way to give a little more helping zooom to the old caps. If you don't mind to spend a little more, replace the main filter caps with new low ESR caps will give you a better improvement. Of course, you can do both :-)

Have fun!!

nadams

If I could find replacement 10,000uf 100v caps in audio grade, I might entertain the thought of replacement. But I can't find a source for them!

Face

nadams wrote: »

If I could find replacement 10,000uf 100v caps in audio grade, I might entertain the thought of replacement. But I can't find a source for them!

EPCOS

http://www.alliedelec.com/Search/SearchResults.aspx?Ntt=10000uf+100v&Ntk=Primary&sid=11F8E16DDA28&i=9&Pst=10000uf+&N=0&sw=y

nadams

Ooookay... I won't be spending more for the caps than I did for the amp just now. Maybe if it dies

heiney9

If I could find replacement 10,000uf 100v caps in audio grade, I might entertain the thought of replacement. But I can't find a source for them!

Nelson Pass swears by computer grade Panasonic filter caps, have you looked into those? Many DIYer's use his suggestion for their projects.

fredv

heiney9 wrote: »

Nelson Pass swears by computer grade Panasonic filter caps, have you looked into those? Many DIYer's use his suggestion for their projects.

Ditto, I am quite happy with Panny. Digikey:
http://search.digikey.com/scripts/DkSearc/dksus.dll?Detail&name=P10038-ND

nadams

fredv wrote: »

Ditto, I am quite happy with Panny. Digikey:
http://search.digikey.com/scripts/DkSearc/dksus.dll?Detail&name=P10038-ND

Except I need to have screw terminals - http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=338-1265-ND which of course quadrupels the price.

fredv

How about this?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=135652
Pretty good price. Of course, this is still almost 3X of the Dayton .... But imagine you still can hear the music for 1 min after you turn off the power :-)

rabies_70

fredv wrote: »

4, one by pass per main filer cap.
I did this before I shipped my pair of GFA-555's the new happy owner.

That's ME!!!! I have 5 555's in my HT rack now. The two from fredv have the mod. The other 3 soon will have it done. I just added the new cap to my CS350ls, now I'm opening up my Adcoms. Do it. The sound is noticeably improved. Thanks again Fred