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MEGA_amp 4th November 2003 01:18 AM

replacement caps - newbie question
 
I have an old pioneer sx-1280 with 4 100V 15000uf Elna caps. I would like to replace them with Vishay's 100V 22000uf caps. Could I go as high as 250V 47000 uf caps without system degradation? Is this neccesary? Or just staying with the 100V with any capacitace value I choose be ok?

JH

djmiddelkoop 4th November 2003 10:13 PM

JH,

I would stick to the original values.
If you go much higher like the 47k uF, you can destroy your rectifiers when switching on the power.
Usually 15k uF is more than enough, and from my experience the quality is more important than the value, soundwise speaking.
I have no experience with the Vishays, but the Elna's are fine.

Hope this helps,
Dick.

EE_Mark 5th November 2003 05:42 AM

Replacing Caps
 
No need to go above 100 volts; it will only add to cost and size. The more capacitance the better (more storage and filtering); you'll get tighter bass and less distortion but, like Dick pointed out, if there is no power-on inrush current limiting circuitry and they use borderline cheap diodes in the bridge rectifier it may stress them. You can pick up a beefy bridge rectifier for less than $10; if you decide to get some big caps you might want to beef up the bridge rectifier at the same time.

li_gangyi 5th November 2003 12:38 PM

yeah...I can get 100V 35A rectifiers for SGD$5 here...or you might wanna go the HEXFred way...faster switching diodes...haven tried them...got no reviews on them...but some people have been singing about them...search this forum for them.

EE_Mark 5th November 2003 02:45 PM

HexFreds
 
I've seen some audio guys talk about how great HexFreds are but there's no reason they would sound better. I'd just find a 25 or 35 Amp bridge rectifier and you'll be fine. You don't need fast switching whrn you're dealing with 50 or 60 Hz. Put a 0.1 uF cap across each diode for noise suppresssion.

li_gangyi 5th November 2003 03:00 PM

I'll be inclined to say yes..but what about soft switching diodes...or even worse tube rectifiers?? which have no switching noise whatsoever...

EE_Mark 5th November 2003 03:30 PM

Rectifiers
 
Personally I'd go with a ~ 35 amp bridge rectifier but if you have the time and money experiment and see if you hear a difference.

li_gangyi 5th November 2003 03:33 PM

haha...yeah...anyways...the HEXFreds can be order in small quantities as samples...and try to get a rectifier...if you want to use it...that is rated at least 35A...and then upgrade your caps.


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