Spring Line Hum

eric barbour svetengr at earthlink.com
Sun Jul 16 10:09:54 CEST 2000

> fusion VC Reverb a couple of times before successfully
> but have always encountered the inevitable background
> hum, sadly in the past, this factor has always stopped
> me using springlines in general. Anyone one with any
> experience of this out there?

Three years ago I built an all-tube spring reverb,
used a 6BM8 (the power pentode used as a cathode follower)
to drive it and an EF86 as the recovery amp. No transformers.
The tube heaters are run on DC. All fit (barely) into a
1U rackmount aluminum chassis.

Hum was indeed a problem. The power supply was remoted, but
it still picked up hum. I resorted to gluing heavy steel panels
to the chassis around the pickup end of the spring. That
finally brought the hum to 60 dB below the "wet" reverb output.
Also, mounted the unit at the top of a rack with an empty 
area below it to keep the transformers of other equipment away.

Make no mistake, springs are a pain to apply correctly....

Eric Barbour

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