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Old 14th August 2008, 02:36 AM   #11
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Joka22, those 10uf 50v caps are for the bridge rectifier.I was "experimenting" and I replaced those 10uf 50v caps with 10000uf per channel.and the bass got a lot stronger and tight.
Get some "alligator clips" and just try more capacitance per channel.that way it is easy to change and compare sound with different capacitors (capacitance).some people say the sound is faster with small caps(10uf 50v) but,I like the sound better with more capacitance 10000uf per channel.Good luck.
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Old 14th August 2008, 03:38 AM   #12
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Default Re: my gainclone in build proccess need some help

Quote:
Originally posted by joka22
I want to use the amp in the stereo mode with one rectfier, do i solder on all 8 mur860 diodes and caps 50v 10uf and i would like to use the amp with out vol pot.
If it says 2 x 22V on a transformer, chances are it's dual secondaries. In that case use one rectifier board with 8 diodes.


Quote:
Originally posted by joka22
I noticed that certain people have used the 50v 10uf caps in rectifers and some have not which one should i choose for best performnace.
The small caps are optional, you can use them, but don't have to. It's best to evaluate both options and choose the one that sounds better
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Old 14th August 2008, 03:54 AM   #13
lineup is offline lineup  Sweden
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Default Small 50 Volt 10 uF capactitors.

Quote:
Originally posted by Peter Daniel

The small caps are optional, you can use them, but don't have to.
I would use them!
It is good to have some caps right after diodes.
This improves filtering considerably. In my experience.
Even if the main electrolytic capacitors are on amplifier board.


It has nothing with sound to do. Even if some say so
It is only to give those LM3875 clean as possible power supply.
And so make the chip work as optimally as can be, electrically.

Evaluate chip amps by sound after some minute power supply detail changes
is nothing I would recommend.
Not even as a Blind ABX and more valid listening test.
Would not give any valid differences in sound. If anyone still like to think so.

But I guess Peter does not mind doing it in his more subjective way.
And who can stop him. Not me, for sure


Lineup - regards to old audio friend peter doing his great service for chip builders
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Old 14th August 2008, 10:19 AM   #14
joka22 is offline joka22  United Kingdom
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i try the 50v 10uf caps first then i will try 80vdc 6800uf as i only have these caps as spare.
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Old 14th August 2008, 10:32 AM   #15
lineup is offline lineup  Sweden
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10 uF or 6800 uF makes no difference
6800 uF is even better.

The important, in my opinion,
is that you use some electrolytic right after the rectifier diodes.

This will make a 2 capacitance filter: ( C-LR-C )
instead of only one electrolytic capacitor at mains pcb ( LR-C ).

LR stands for Inductance+Resistance of the wiring from the rectifier pcb.
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Old 14th August 2008, 10:39 AM   #16
joka22 is offline joka22  United Kingdom
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okay i kinda half way understand that - what i have read on g.randy slone book is that caps help smooth the powersupply and smoother sound as the amp requests more power at high bass sounds so the caps help it by discharging the current to the amp without effecting the power supply. 50 watts per channel 6800uf is about right based on g randy slones thoery on caps for number of watts of per channel amps.
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Old 14th August 2008, 10:45 AM   #17
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joka22

Could you mount the chips on the other (flat) side of the heatsink?

I would be a bit concerned about the "T" nut slot running down the chip allowing hotspots to form where the chip isn't touching anything.

John
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Old 14th August 2008, 10:47 AM   #18
joka22 is offline joka22  United Kingdom
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yeah i tried to but the chip amp circuit board comes in the way and the chip itself cant reach the flat side of the heatsink. trust me dremeling is alot of work honestly the bloody disc break pure solid heatsinks.
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Old 14th August 2008, 11:05 AM   #19
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joka22

Could you lay your hands on some thickish alloy offcuts? You could mount the chip to an aluminium block to act as a spacer with thermal paste between it and the heatsink.

It would also put the heatsink between the chips and your transformer to give some screening, and keep the signal wires shorter.

John
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Old 14th August 2008, 11:08 AM   #20
joka22 is offline joka22  United Kingdom
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I have thought of that but i dont have any of these parts i wonder if someone sells heatsink at a reasonable price.
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