ps filter cap bypass question?

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crippledchicken

crippledchicken

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Joined 2003
#1
hi, my power amp has 2 10,000 mfd. and 2 12,000 mfd. caps, one of each per side. i bypassed each cap with a 0.1mfd. metalized polypropylene film not the best i know, but all i had on hand. the sound seems to be alot brighter, with most of the power in the mid to high frequencys. should i try different values of bypass caps, give these caps break in time, or no bypasses at all? thanks for your input crippledchicken 🙂
 
#2
It's well known that using small bypass decoupling caps on the larger caps in the PSU, can give a more well defined sonic reproduction.

with most of the power in the mid to high frequencies.
Click to expand...
Is this to be understood as the whole sonic of the amplifier has changed to the brighter??? It's more likely that the sonic of the mid and top has become more clear and well defined....

Yes. You can try different types and values. A basic rule is that the decoupling caps should be at least 100 times smaller that the big cap it's bypassing.

You should also use small decoupling caps on the PSU rectifiers..
Try some 100 nF across each diode in the rectifier bridge. These can also result in even more well defined sound

What amp is it???
 
#3
hi ACD, the sound of the amp with the bypasses, seems that it is more detailed and refined, at lower volumes say 9:00 but, seems when i turn it up to 10:00 or more the vocals seem to get more harsh, and not as easy to understand as, without the caps and the extra brightness kind of masks the detail. my listening distance is rather close like 8 0r 9 feet tops. if i sit in the other room which is all open area, the sound seems more mellowed out. could i be too close? sort of like being to close to a live band to make a proper judgement? i have replaced the original cheap inline bridge rect. with home made 30 amp stealth diode bridge awhile back which seemed to be a big improvement. also replaced the fixed lm7812 and lm7912s regulators with lm317 and lm337s also awhile back so, i believe those components should of had plenty of burn in time. also, the filter caps i'm bypassing are nichicon gold tunes. thanks very much, crippledchicken 🙂
 
#4
Hi Crippledchicken,
I'm not the greatest speaker expert, however the "correct" listening distance from the speakers depends on many things.... The speakers, the room, the volume etc...
I use High End VIFA and Audax tweeters in my speakers, and if I'm close to the speakers (2 meters=6 feet???)) the tweeters can sound a bit hard, however angeling the speakers just a bit changed that..... Try some different positions for your speakers 😉

I will say that bypass caps in the PSU can only make an amp better... The reason for your sound experience could be, that the amp is now much more clear and defined, and are now showing the some problems in the rest of your system.... Is it the same for both CD and Tuner??? Do you have some kind of reference CD so you could try different speaker angels and amp settings???

Also... What kind of speakers are you using??? Do they match the amp???
 
#5
well ACD, i think you might be right about the speakers. they are just a cheap set of technics with replacement tweeters from radio shack. i bought them used and after you mentioned about the speakers, i decided to check them out real good. for sure, someone has replaced the original tweeters with radio shack brand. of course the originals probably wer'nt worth a crap either hehe. i don't see any possibility of any better speakers in the near future so, maybe i can mount some L pads to help balance them out a little. i think i will check into a good reference cd of known good testing qualities instead of several different cds since there all recorded differently any way good idea! thanks you've been a big help and HAPPY NEW YEAR, crippledchicken 🙂
 
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