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Audio Buzz prob.

Since this is my area of expertise, I guess I should comment on the problem
that Ted, Howie, and many other installers run into with telephones and neon. 
Obviously, since they make neon telephones the two can co-exist.  You will
find that if there is an audio problem with neon you will have it in an
unbalanced line first.  These are usually lines from guitars and keyboards
that have a 1/4 in. jack.  Even though they may be shielded (and usually are)
the shield may "sink" the stray interference but since the other lead is
relative to the shield it will now pick up the differential voltage as noise.
The best noisless cables have a shield and 2 wires that reference to each
other and not the shield. These wires are twisted so that if one picks up an
induced field the other will pick up the same field in the opposite direction
and therefore cancel. The other problem is that unbalanced systems are higher
impedance which makes the inputs more sensitive to smaller voltage changes
like induced hum. Telephones are pretty bad as far as neon problems are
concerned.  The technology is rather old and is not up to today's audio
standards like they would have you think.  While the new stuff has digital
processing and fiber optics, ANY part of a serial system that is deficient
will cause a problem.  Most phone systems are not shielded so are ripe for
induced and EMF problems.  I use the phone to check for problems with audio
and neon just because it is so bad. Makes a great detector<g.>.

 I know, yea, yea, yea, how do I fix it?  You have two choices. Fix the neon
or fix the phones.  It reminds me of the typical computer problem.  You
install a sound card and your machine crashes. You call Win95 tech support and
they say it's the sound card prob. You call the sound card people and they say
it's the computer manufacturer's problem, etc, etc.  The customer doesn't want
to hear about how if the neon lights, well, that's what it's supposed to do
and tell the phone co. to fix THEIR problem.  So now you have to fix the neon.
With traditional transformers (iron core jobs) it is relatively simple as long
as EVERY bit of high voltage is kept FAR from ANYTHING ground or the other HV
lead. Also, for stage work where audio is crucial, I never go down to less
than 26 ma. unless the sound system and cameras, etc. are bullet proof.  It
only takes 1 or 2 bad audio/video cables or weak shields from something
running over them to cause problems.  Back to that term "headroom" again. 
Places to check for problems are the first legs out of the transformer HV. 
That is where the voltage is the highest and most apt to micro-arc. I also use
the solid states (although as Kenny says they are not as bright) in situations
where audio is a problem and dimming is not required.  I've used TFT's and
Neonix although I've had a problem with the Neonix field detection circuit
shutting of other Neonix units in proximity. definitely dead quiet as far as
audio, though.  I just made a neon wave for the Beach Boy's monitor engineer
and used the Tech 2000 for it.  If you put the wireless pacs (for in-ear
monitors)  within a foot of it there was a very slight high freq. squeal. I've
used those right next to guitar pick-ups with no problems.

 Getting back to Ted's problem.  It does sound like you may have found what it
is.  If you have an insulating coating as you suggest that would certainly
make a nice capacitor that would cause noise problems as it broke threshold.
Guess you could say you created a high impedance neon circuit.  Usually,  it
is hard to isolate one thing without looking at the neon.  There are so many
things that can cause interference and usually only a few right ways to avoid
it.  Just the nature of high voltage circuits.  I usually ask is it a MMMM or
a ZZZZ?  It helps to establish the source. Even the sputtering of the
electrons hitting the trode creates an electro-magnetic noise floor.  Usually
more prominent with neon tubes than merc.  The radio ranch boys (in charge of
all the wireless stuff for a show) have some great and expensive equipment for
finding what is interfering with them. Particularly bad are CAT scanners and
MNR machines.  They HATE when the show is across the street from the
hospitals. SOMETIMES you can get them to not use the machine for the 1-1/2 to
2 hours the show is on.  WHO'S problem did you say it was?<g.>

 Keep us informed on how you make out.

  E-mail from: Tom Biebel, 10-Dec-1995
 

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