[sdiy] OT: scratch filter for vinyl

[KA4HJH]

>I've heard about static on records before, is there a way to tell static
>noise from scratch noise on a record?  How does one go about discharging the
>static from a record?

Ah, the sound of static discharge from a turntable.

How to describe it? It doesn't sound quite like anything else I've ever
heard--except maybe a percussion patch on a modular with the VCF set to
"high and thin". It's a noise with lots of high frequency content--probably
goes well out of the audible range. There may be a sort of "click" or
"snap" at the very beginning, followed by a very "thin" noise that slowly
dissipates. Almost like air leaking, but more of a narrow band noise.

Some LP's are better about static buildup than others--it depends on what
they add to the vinyl. I once bought a UK pressing of Jean-Michel Jarre's
"Equinoxe" that sounded much better than the US pressing but had a static
discharge about once a minute, making it unlistenable. It's quieter than
most clicks and pops you hear on LP's but REALLY ANNOYING since a big one
can last several seconds.

Simply cleaning the record with a Discwasher brush actually made the
problem worse (yes, I used the accompanying cleaning fluid). The solution
to the problem was to acquire a Discwasher Zerostat 3 "pistol" which worked
like a charm. Discharged all the static long enough to play the entire side
without a single "pfizzz".

I have no idea if these things are even for sale anymore. It's actually
nothing more than a piezoelectric crystal (like the one in a barbecue grill
igniter) mounted inside a pistol-shaped housing. When you squeeze the
"trigger" the crystal is compressed producing a very high voltage potential
which is applied to an electrode in the "muzzle". There's a technique to
how you use the device on an LP but it's very simple.

These days I mainly use mine to test neon lamps, gas-filled tubes, etc.
-- 

Terry Bowman, KA4HJH
"The Mac Doctor"

"It gets calls when nothing else works"--W. Eugene Scott, PhD, explaining
somewhat facetiously why a "TV preacher" was smoking a cigar.