MOTM

Try not to laugh too hard, I know these questions reveal a lot of
ignorance :)

Why is star grounding better than a D*****r style ground bus?  The circuit
topologies are equivalent, it seems to me (the MOTM power distribution
board being analogous to the ground bus).

Also, why doesn't every patch cord you plug in turn into a hum inducing
ground loop?

thanks,
Chris Jeris (dismembering damaged pots with cutting pliers)

I have no idea about the pros and cons of star grounding vs. others, but
I'll take a stab at the second question:  everything shares a common ground!
:)  "Ground loops" can happen when two items don't shre the same ground...
but in a MOTM system, everything shares a common ground.

Now, if you patch your MOTM into another item, which has a *different*
ground (i.e., different wall outlet, possible), you may get hum.  This is
why power strips are a good idea.

Searching the A6 archives (www.midiwall.com/archives/a6) will turn up a
small set of posts, which may be informative.  I'm sure there are also
plenty of posts on the matter in the archives for AH and this list.

--PBr

-----Original Message-----
From: Christopher Jeris [mailto:cjeris@...]
Sent: Thursday, June 28, 2001 12:39 PM
To: motm@yahoogroups.com
Subject: [motm] Dumb ? on grounding


Try not to laugh too hard, I know these questions reveal a lot of
ignorance :)

Why is star grounding better than a D*****r style ground bus?  The circuit
topologies are equivalent, it seems to me (the MOTM power distribution
board being analogous to the ground bus).

Also, why doesn't every patch cord you plug in turn into a hum inducing
ground loop?

>>>>
Why is star grounding better than a D*****r style ground bus?  The 
circuit
topologies are equivalent, it seems to me (the MOTM power distribution
board being analogous to the ground bus).
<<<<

I'm sure Paul can and will answer this, but as I understand it:

Equal length paths from termination points to the power supply =
 
Equal resistance from power termination points to the power supply =

Equal voltage drop at each termination ground (assuming roughly equal 
current return on each ground) =

No voltage difference between ground points =

Lowest hum and noise.

Or something like that.

Moe

Moe get a 94 on the quiz.

<Paul S>

----- Original Message -----

From: <mate_stubb@...>
To: <motm@yahoogroups.com>
Sent: Thursday, June 28, 2001 7:30 PM
Subject: RE: [motm] Dumb ? on grounding


> >>>>
> Why is star grounding better than a D*****r style ground bus?  The
> circuit
> topologies are equivalent, it seems to me (the MOTM power distribution
> board being analogous to the ground bus).
> <<<<
>
> I'm sure Paul can and will answer this, but as I understand it:
>
> Equal length paths from termination points to the power supply =
>
> Equal resistance from power termination points to the power supply =
>
> Equal voltage drop at each termination ground (assuming roughly equal
> current return on each ground) =
>
> No voltage difference between ground points =
>
> Lowest hum and noise.
>
> Or something like that.
>
> Moe
>
>
>
>
>
>
> Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
>
>

Download the grounding paper on the following webpage for a good overview of 
audio signal shielding and grounding:

http://prosoundweb.com/studyhall/studyindex.shtml

For THE definitive information on shielding, grounding, and power 
distribution, get the following $45 book:

http://www.amazon.com/exec/obidos/ASIN/0240802861/prosoundweb/107-7208361-3495

729

Ivan