How to Emulate Feedback Guitar with Synthesizers

Posted on by craiganderton

Believe it or not, synthesizers can emulate expressive, guitar-style feedback

I’ve used this “feedback synth” technique on quite a few songs, and people often wonder how the heck I did it. Well…it wasn’t feedback guitar, it was synthesizer—and you can get the same kind of effect. It’s really quite simple.

THE THREE ELEMENTS YOU NEED

  • Use unprocessed guitar samples. The base program I used was a sampled Gibson Midtown guitar, with no effects or other goodies.
  • Process the guitar through an amp sim. I used the custom CA-X “Hard Rock” amp sim I designed back in the day for Sonar, but any amp that floats your boat all work. Distortion, baby!
  • Add artificial feedback.

HOW TO CREATE ARTIFICIAL FEEDBACK

Simply layer two sine wave to produce the “faux feedback.” I transpose one 19 semitones (octave+fifth) above the fundamental, and the other 31 semitones (2 octaves+fifth). The low-pitched one has an envelope that builds up to a peak in about two seconds (see the screen shot above), and then decays while the higher-pitched feedback appears over about 3 seconds. It’s important to set these envelopes for a believable attack time—long enough to that the feedback shows up with a long, sustained note; not so long that it never shows up; and not so short that it shows up all the time. Having done a lot feedback guitar in my time (ahem), it doesn’t happen instantly—you have to coax it into happening. The attack time represents the time needed to coax it into happening, and to jump from one harmonic to a higher-pitched one.

If you used Cakewalk Sonar back in the day, the Midtown guitar patches for Rapture Pro/Rapture Session in the 2017.08 update included artificial feedback, so just follow your Rapture variant with the CA-X “Hard Rock” amp, or use something like a Marshall emulation from the Line 6 Helix, Native Instruments Guitar Rig, IK AmpliTube, etc. But also remember that you need to think like a guitar player—the pitch wheel becomes your virtual whammy bar, and use the pitch wheel for vibrato—not the mechanical mod wheel vibrato. After all, that’s not how guitars roll.

Happy feedback…and don’t forget the ’60s light show!