Nooby has a few ??s

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stoo
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Nooby has a few ??s

Post by stoo »

Hello everyone! This is my first post. Great forum!!
I have a few quick questions.
Firstly I came here looking for info/schematics ect. for the Francesca amp. can someone direct me to a link. I've searched and found some pix but no schematics.
Secondly. Why is everyone using those great masses of filter caps. instead of multi sectioned cans?
Thanxs in advance!
Stew
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Allynmey
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Re: Nooby has a few ??s

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Elcabong
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Re: Nooby has a few ??s

Post by Elcabong »

stoo wrote: Secondly. Why is everyone using those great masses of filter caps. instead of multi sectioned cans?
Thanxs in advance!
Stew
The advantage of separate caps is that it gives you the opportunity to arrange grounding as you wish. You do not have this option with the multi caps common ground.
JimiB
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Re: Nooby has a few ??s

Post by JimiB »

but even thought the grounds are not all attached don't the wires all go to the same grounding terminal?
Moose
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Re: Nooby has a few ??s

Post by Moose »

That's a fussy issue.

First, yes. They do all go to the same terminal. However, the point of good grounding scheme is to keep heavy ground currents from the high power stages away from input signal stages. The higher current grounds can actually modulate the preamp ground and if that causes any noise, it gets amplified in each stage.

Also, there's the issue of ground loops and, theoretically, you want to keep each stage isolated for absolute minimum ground loop hum. If you're using a dual section cap for the PI and the preamp, for example, you're going to have a problem being really strict when doing that.

Personally, I can see no problem using a dual 40uf section can for the first cap, and I've even used the 50-20-20-20 JJ cap in a build that was moderately quiet (though NOT without its problems when I first started it up). However, the system KF used really does lend itself to exacting control of power supply grounding. I'm starting to use a version of it even for more conventional "marshally" style amps.
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