Jan Hammer

For more movement in the sound, Hammer used a slight bit of flanging, coming from an MXR black-face pedal (now reissued by Dunlop).

Mentioned by former Systech president Greg Hochman in Analog Man's Guide To Vintage Effects, as transcribed by Joe Gore in this December 12, 2012 tonefiend.com article.

We did a custom preamp for a guitar that Greg Lake had. We were in Kalamazoo, where Gibson was….Ritchie Walborn had designed it; others asked us to build one for them. It eventually became what we called the Harmonic Energizer. It was a variable-state filter, which was kind of high-tech at the time, and it got a pretty good following from Joe Walsh to Jan Hammer….It allowed you to dial in up the Q of the filter, and by changing the frequency of the filter, you actually had the ability to choose what key you were going to have sustain and feed back. The thing actually had 55dB of gain when you got it up to a high-Q filter, so it didn’t allow you to be subtle onstage. It was dangerous, but it had a unique sound to it.