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I have this way of thinking about two different kinds of guitar feedback:

-Gain based feedback
-Volume based feedback

Gain based feedback can happen at any volume, and requires distortion, adds sustain to notes/harmonics, etc.

Volume based feedback happens at high volumes, doesn't require distortion and is much more sensitive to physical motion (motion of the instrument changes the pitch of the feedback very easily). There is a greater variety of the actual tones that feed back, more tones than the guitar itself can make via notes and harmonics. Microphones feedback in this way.

I'm hoping to have my guitarist use a very low-gain / clear distortion, but I still want lots of feedback. Are there any tips for getting more of this "volume based feedback" that I'm describing, besides the obvious "use more cabinets and turn up louder"?

Here's some examples that feature this sort of harsh feedback I'm trying to achieve:

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I have this way of thinking about two different kinds of guitar feedback:

-Gain based feedback

-Volume based feedback

I don't believe that's correct. When a positive feedback occurs the output signal of the system (guitar string → pickup → amplifier → speaker → air) comes back to the input of the system (guitar) and it is amplified again even more. This process would repeat infinitely, resulting in an infinitely loud sound, but in practice one or some of the elements (commonly: some amplifier circuit in an amp, preamp, effect pefal) will soon saturate resulting in sound distortion and also steady volume.

In the recordings you linked I can hear a fair amount of distortion, it doesn't really sound unusual to me. You achieve such sound by tweaking settings of the amplifier, maybe distortion pedals and eq, maybe choosing one amp or can over another. It also matters what notes you play. With guitar distortion most intervals will produce very "dirty" sound.

To achieve feedback that doesn't involve distortion, possible options are:

  • use strong compression or limiting effect
  • use sustain device like ebow, or sustain pickups (e.g. Fernandes, Moog guitar...)
  • send guitar sound to two amps (preferable in separate rooms). Let the guitarist stand next to an amp with high distortion, while recording the amp with clean sound.

but from what I understand from your post, this is not the sound you're looking for.

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    Ahh you just helped me clarify something: The feedback I'm looking for is the kind where the strings DO NOT vibrate at all. I will mix in the strings vibrating with notes, etc, but I really want that direct "pickup to speaker" hissing shriek .
    – JacobIRR
    Apr 15, 2021 at 20:34
  • @JacobIRR Indeed, you can get feedback from the pickups, especially bad quality pickups (pickups that can move, or that have coils that can move)... This is not something I ever explored much. Apr 15, 2021 at 21:06
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The terminology in your question has nothing whatsoever to do with what you are looking for, judging from your additional comments.

There is acoustic feedback for electric guitars (involving the strings) and magnetic feedback (feeding directly from the speaker into the pickup). It would appear you are looking for the latter.

For magnetic feedback to work, you should not be using humbuckers since they are, by design, insensitive against somewhat homogeneous external magnetic fields. Single-coil pickups are better for that. Use a single pickup with full tone, at least until you manage getting first results.

Dampen the strings and hold the relevant pickup really close to the speaker.

You stand better chances with older speakers that may have less elaborate magnetic shielding. Basically magnetic interference is not an overly desirable trait (you want to be able to put an amp near a speaker without howling as a result) so technology tries to avoid it to various success.

Cabinets with a single large speaker may be the most likely candidates for smooth howling.

Of course, piezo tweeters (which work with electric rather than magnetic fields for activation) are completely useless for that feat.

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  • That’s a great point about single coils
    – JacobIRR
    Apr 16, 2021 at 1:00

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