Hey all,
I've got an old ~50s era Presto Recording (so I believe) tape machine amplifier that somebody wired up as a preamp. If I have the output sent directly to a record-enabled track in Pro Tools and I then power the preamp off, the unit begin to generate a very loud hum on the output signal. If I pull AC power the sound is gone, only to return when I plug it back in. When I shut the preamp off, it can take a few second for the noise to generate, as if there's a feedback loop of some sort growing after power off.
Is this a sign of anything in particular?
The unit has been in storage for a few years. It passes a microphone signal but that is riding on a lot of noise now.
On an aside, I just moved to the Portland, OR area. Do you all know any locals that specialize in maintaining or rebuilding vintage equipment?
Thanks!
Preamp Hum: Plugged into power but powered off
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- steve albini likes it
- Posts: 361
- Joined: Sun Sep 26, 2004 8:57 pm
- Location: Portland, OR
Re: Preamp Hum: Plugged into power but powered off
You could try a different outlet?
As a quick fix, maybe plug it into a power strip and turn off the power strip when not in use?
As a quick fix, maybe plug it into a power strip and turn off the power strip when not in use?
-
- steve albini likes it
- Posts: 361
- Joined: Sun Sep 26, 2004 8:57 pm
- Location: Portland, OR
Re: Preamp Hum: Plugged into power but powered off
The unit is on a surge protector and none of the other rackmount units on the same surge protector exhibit the issue. I'm certain that there is a problem with the preamp and was just wondering if that specific symptom would mean something in particular to more experienced tinkerers.
Re: Preamp Hum: Plugged into power but powered off
Many systems do this, it's simply that the one is powered off.
Doug Williams
ElectroMagnetic Radiation Recorders
Tape Op issue 73
ElectroMagnetic Radiation Recorders
Tape Op issue 73
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