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In the Forum: Melquiades Amplifier
In the Thread: Bias help

Post Subject: The geometryPosted by N-set on: 3/19/2011

This is what I try to stick to:
Try to create closed magnetic (steel) loops around magnetics. Ideally acompany it
with closed electric (copper) loops. This I think Pieter has done that already for you, but,
as Romy impicite suggests, double boxing will not hurt for sure.
The transformer and the rectifiers should be as close as possible: the rectifiers' switching
kaka can (and usually does)
excite the transformer secondary and polutes the area with RF. Keep it as far as possible
from the input stages. Think diagonal. The PS input choke sees a huge voltage swing, so there are strong
electric and magnetic fields around it. Isolate it well too. From both the trafo+rectifier and the signal path.
Distance is our friend, the dipole fileds die out with the distance squared.
Orient the cores of your magnetics 90deg wrt each other, this will supress the magnetic cross-talk.
Caps don't like heat (nor vibrations) and 6c33c is an open oven. Sorbothane O-rings between the input tube
sockets and the chassis and below the caps would not hurt.
The usual things: twisted pairs (keep the low resistance loops as small as possible),
star grounding, voltage regulators as close as doable to the regulated tubes, etc.
The excellent source to understand some of those things
is this:
"Grounding and Shielding Techniques"
Ralph Morrison

Goos meditative mood, a small shot of a prime Polish vodka and ample time to visualize
the things and play like with lego helps!
Bets luck,
N-set

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