Re: let me restate that...

Thanks, Pat.
I had read that article and that's why I changed my grounding system to star grounding (from having lots of wires soldered to the chassis at various locations). It is confusing because the article describes star grounding as generally the way to go yet Stephen is saying that is far far from the truth. I'm not sure what to believe.

Pat wrote:
On Sat, 24 Jun 2006 01:49:57 GMT, "Stephen Cowell"
<scowell@xxxxxxxxxxxxx> wrote:


"guitarPsych" <none@xxxxxxxx> wrote in message
news:5JudnTgSyJ045AHZnZ2dnUVZ_sSdnZ2d@xxxxxxxxxxxxxx

I think you're right, it is related to grounding. I notice now that
there is a strong hum that goes away if I touch the strings or the amp
chassis. But everything that's supposed to go to ground is going to
ground, using a 2 point star system. It seems somehow the whole thing
is not grounded. I tried another amp in the same electric socket and
get the same problem, but at about half the level (loud hum but only
half as loud as the hum in the amp I built). I'm believe I have
eliminated any ground loop using the star system, but somehow I'm just
not getting the whole thing grounded enough... how does one ground it
more? It's like Spinal Tap... I need it ground to eleven... but this
one only goes to ten.

Star ground is poo.. buss grounding has more of a hope
of grounding things near where they need to be. You
want to avoid impressing signals from different parts of
the amp into each other... grounding all the preamp
stuff in one place does not do that.

Examine an old point-to-point RCA pa head and
check out the long buss-wire grounding scheme.
Out at the end, the input circuits are grounded.
The filter for each section is grounded *at* the
section, just like it looks on the schematic.
The bigger the signals get, the closer the ground
gets to the big PS ground, where the chassis and
buss grounds meet.


To follow up on Steve's last sentence, here is more on grounding and
star grounding. It matters what component is grounded to which grounding
point.

http://www.aikenamps.com/StarGround.html

.

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