[sdiy] spring reverb & hum

[Magnus Danielson]

From: "mdimmm at hotmail.com" <mdimmm at hotmail.com>
Subject: [sdiy] spring reverb & hum
Date: Wed, 13 Nov 2002 23:54:50 +0100

> Hello

Hi!

> My Doepfer A-100 Modular's spring reverb picks up a terrible amount of hum
> from the transformer. Doepfer's only suggestion was to move the unit further
> away from the rack with the transformer in it.
> 
> Any suggestions on how to make a spring reverb less hum-sensitive?

Well, an old trick from the tube-days where (where the tubes where fed with
6.3V AC in many cases) to actually insert a little of the power-feed into the
signal change, and trim it to maximum cancelation. Propper choice of polarity
is naturally an important aspect.

Naturally, things like keeping distance and magnetic sheilding can be used.
Another trick is to have an additional receiver coil and use it as a pickup for
"stray magnetic" in an attempt to make the compound magnetic assembly more
distance sensitive. There are many variants to it. I've seen it used in HPs
near-field probes for instance. Lovely stuff to work with.

That's just a few that popped up in my mind.

Cheers,
Magnus