Hum a Telev. tune / RE: (TV) OT: Tech Qs

["Leo Casey" <LeoCasey@comcast.net>]

Thanks Maurice, that was very helpful.  Some answers to your questions below

>Is your house using two-prong wiring only?  

Yes, except for new kitchen (house built in 1900).  

>Or is your stereo two-prong-only? What kind of tuner/amp?  Solid state or
>vacuum tube?  Two or three prong?  How old is it?

Amp is Pioneer 9100 bought in 1973 (unfortunately solid state) has given me
hi quality performance except for rare visit to repair shop---it's a
semi-cult item; its male powercord and all its female plugs are two
prong---(however wherever I can I use a three-prong adaptor(s) for my two
prong power cord(s) I do.  

>I can't see why you'd need to do all this, unless you're getting a lot of
>hum.

I am afflicted with a rare but sometimes fatal disease called audiophilosis.
I read a long time ago in a hi fi mag that for optimum sound quality
(including, but not limited to, the minimization of a music system's hum):

1) You should always try to keep all your stereo's (i.e., music system's
components') power cords separate (and as far away from) all your input and
output (i.e., rec/in and monitor/out) cables---even to the extent of trying
different combos of placements of the components relative to one another.
[My present music setup includes a cd player, DVD player, amp, tuner,
turntable, dbx-117 dynamic range expander/compressor, (and cassette deck and
Reel-To-Reel), so have 8 pairs of L-R cables and 6 powercords. I use very
high quality cables, and yes, I know they're already shielded  :>) ]; 

2) (If you have one) position your turntable as far away from your amp (and
of course, speakers) as possible---albeit you are limited in this by the
relative shortness of hi-end phono cables [turntable is a Thorens-166 Mk-II
with some home modifications (cork on platter; anti-radar paint/'goop' to
damp tonearm) and cartridge is Grado Z1+ ];

3) After you attach all your components' ground wires (if present) to your
amp's 'little grounding screw contact', ground your amp by attaching a
(maybe long) ground wire from amp's 'little grounding screw contact' to a
pipe-plumbing in your home, or optimally run a ground wire from your amp to
a steel stake you have sunk into the earth outside your home;

4) Turn up amp to a high level without playing music and listen to the
resultant level of system's hum; then after shutting off amp, try reversing
the way a component's two-prong male plug go into its corresponding female
outlet; turn amp back on high and listen again to see if hum got better or
worse; continue this procedure one-by-one for each component's powercord
connections until you find the combination that gives the smallest amount of
hum/noise.

Not wanting to drill a hole thru my living room's floor to my cellar and run
a ground wire thru it from my amp to the main water line coming in from
sidewalk [maybe later], I thought an easy substitute to #3 above might be
grounding my amp to the little metal screw that attaches 2the cosmetic,
rectangular-plate to the wall-electrical (two-prong) house outlet(s).

>If you're using just the turntable, 
No lots of other stuff [see above]
>you'd want a phono preamp, and that should have the little grounding screw
>contact on it.

No outboard-preamp for phono, I connect turntable's original ground wire to
the supplied little grounding screw on amp.

>> or should I remove the wall outlet receptacle-box and rewire my ground
>>wire to the ground wire inside the wall-outlet box inside the wall?

>That seems rather extreme.  I have to ask what isn't working when you 
>plug the stereo in the usual way, without all this extra effort?

*Important fact*: in all of the above discussion when I talk about a music
system's 'hum' (or other flaw), I'm talking about a relatively small amount
of hum that the average listener might not even notice or be concerned with.

>Two counterexamples: aluminum foil is non-ferrous, and so 
>non-magnetic, but conducts just fine.  From the other side, if you have 
>a magnet that's powerful enough, it might attract something with a 
>ferrous core, though that core could be surrounded by an insulator of 
>some kind.

Got it. 
It's hard to believe I was an undergraduate in EE many moons ago :>) 

Leo
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