Twin Peaks is a tremolo that consists of two separate analog audio paths whose volume can be modulated.

One is a low-pass and the other a high-pass filter.

When you modulate both in sync it sounds like a regular tremolo where the whole audio spectrum is modulated at once.

When you modulate them out of sync your output signal will pan from the low pass to the high pass signal and you will get interesting phasing effects where the two filter curves meet.
This is what is usually referred to as a harmonic tremolo.

While the Tap tempo and LFO functions are digital, the audio path is 100% analog. The tremolo effect is achieved using optocouplers.

bypass switch: The pedal uses a relay (true) bypass. and soft momentary switches. If
you give it a short tap (<0.3sec) it acts in latching mode. If you press it for more than 0.3sec a you are in momentary mode.

tap tempo switch: Tap in the desired tempo and use the multiplier switch to set its range.
Tip: If you tap the switch just once the LFO will reset to the start of the wave cycle.

rate: Adjusts the rate of the LFO.You can set its range with the multiplier switch.

tap tempo multiplier switch: Allows you to set the range of the manually adjusted rate or multiply the tapped tempo by 1, 2 or 4.

env: Adjusts the sensitivity of the envelope detector that will affect the LFO rate.The higher you set it, the more your playing will vary the LFO rate.

env mode: If set to the middle, it deactivates the envelope detector. If set to up:The rate will increase as the signal incresases. If set to down:The rate will decrease as the signal increases.

sym: The symmetry knob allows you to skew the shape of the LFO to the left or the right.When using the square wave, you can set the length of the “off” in regards to the “on” periods.

depth: Sets the depth of the modulation. Tip: if you turn depth completely down, you can use the pedal as a filter using the tone knob and even have a substancial boost available, adjustable with the gain knob.

tone: Adjusts the balance between the bass and treble signals.

gain: Adjusts the overall volume.