Running Line Out back to input

[Feloniuspunk]

Clumsy thread title but I wasn’t sure how to word it. Many amps have dual input jacks, a High Gain input and a Low Gain input. Many amps also provide a Line Out jack on the back panel for feeding the output signal directly into the board at a recording studio for example. Has anyone ever tried running that line out signal back into one of the inputs of your amp?

Theoretically it shouldn’t hurt anything since the signal is already millivolts. I’m trying to see if doing that would in affect be akin to creating a positive feedback loop to provide more or even infinite sustain.

The only thing I can think of that might be necessary for it to work safely is adding a resistor of some kind to control the level.

[6v6ster]

I like the experimental attitude, I tired this myself about a year ago. It results in massive squealing.

if you don’t kill it quick enough you do risk overheating your speaker since it’ll be pushed forward for the duration of the chaos.

[Feloniuspunk]

Interesting. I presume you went direct from line out to input with just a cable, no potentiometer to ground in between. Also, it just occurred to me, the two signals might be out of phase. It might be wise to add a capacitor in addition to a potentiometer, as a crude buffer. I wish I had an oscilloscope. Then I could determine signal level, phase, all kinds of info, before damaging anything. Thx for the reply. Thinking it through, I suspected squealing was one thing it might cause.

[sgosnell]

This is not a good idea. If it was, it would be common. You should know that you're not the first person to ever think about this.