• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Carlson Super Probe

Has anybody else had fun poking around a tube amp with a "Mr. Carlson Super Probe"? (an extremely sensitive non-contact signal tracer and noise finder that uses a small speaker to create an audio output.) I picked one up to troubleshoot noise issues. Maybe I'm misunderstanding its utility, but for devices prone to intermittent noise--like DIY tube amps--it could be an awfully easy way to differentiate between a troublesome resistor, dirty tube pins, a bad solder joint, etc.

I see folks have recommended cheap sniffers in other threads in the past, but the "noise" feature here seems pretty clever. If this is a terrible idea, I'll be curious to hear how!

My first impression is that it works like magic. I assume that because of its sensitivity, what it picks up may or may not make a difference in the actual amplifier performance. But it is fascinating to hear the noise generated in a power supply or even just near AC input wires. Amusing that different devices in my house seem to pick up different radio stations. Even if you are slick with a 'scope (I'm not) hearing can be more fun than seeing.

I had already found the problem I bought this to trace by just continuing to throw parts at it (bad pot in a bias circuit, ultimately). But if what it picks up means anything, my Coleman regulator board is just far enough away from the HV rectifiers on this amp on one side, while the twisted pair of AC running to the switch is probably too close on another. And either way, what a difference a bit of aluminum tape makes, at least for goofing around purposes.

I thought this would just be for when I have problems. But the next time I build, I might use this to play with chassis layout for noise purposes before I start cutting holes. And now, I feel compelled to line these wood chassis with the aluminum tape like the tin foil hat crowd. But I'll try to not get carried away.

Paul
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