-Led Zeppelin - No Quarter - Uses what type of keyboard synth to get that sound?
"Jones used the VCS3 to create the underwater "wobble" effect on "No Quarter." He ran the audio signal of the Hohner piano through the filter, and modulated the filter with a sine-wave LFO. This made the filter rise and fall rapidly, creating a shifting tone not unlike a phaser, or Leslie speaker."
(source: John-Paul Jones keyboards site)
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