Pearl CH-02 Chorus schematic

The Pearl CH-02 Chorus is a long discontinued pedal with a superb sound. It has 4 knobs: DEPTH, SPEED, TONE and MIX BALANCE. The TONE knob only adjusts the tone of the effect sound and The MIX BALANCE adjusts the mix ratio between the direct and effect signal.

Schematic diagram of Pearl CH-02 Chorus
Fig. 1: Pearl CH-02 Chorus guitar pedal schematic diagram

Operating instructions from the user manual:

Control Knobs:

Mix Balance: Used to adjust the mix ratio between the direct sound and effect sound. When control is set at middle position, the mix ratio is 1:1. Turning clockwise increases the mix of effect sound and counterclockwise the mix of direct sound. Turning all the way clockwise gives effect sound only and vibrato may then be conveniently added. Turning all the way counterclockwise gives direct sound only.

Tone: Controls the tone of the effect sound. Turning clockwise gives brighter tones. Since this control neither influences direct sound nor the overall tone, extremely sharp chorus effects can be achieved.

Depth: Adjusts the depth of chorus effect. Turning clockwise increases depth.

Speed: Adjusts the speed of chorus effect. Turning clockwise increases speed.

Typical settings:

1. A setting for a natural chorus effect (effective for arpeggio or chord backing):
Mix Bal: 0, Tone: 5, Depth: 3, Speed: 2.

2. A setting for emphasizing the vibrato effect for mild tones:
Mix Bal: Eff(max), Tone: 0, Depth: 3, Speed: 6.

3. A setting for phaser type use:
Mix Bal: 1 (Eff side), Tone: 5, Depth: 3, Speed: 5.

4. A setting for the sound of a 12 string guitar:
Mix Bal: 2 (Eff side), Tone: 8, Depth: 4, Speed: Slow (min).

Pearl CH-02 Chorus picture


  • 4 Control Knobs: Speed, Depth, Tone, Mix Balance
  • Connectors: Input, Output, AC Adaptor
  • Input Impedance: 1MΩ
  • Output Impedance: 10kΩ
  • Maximum Input Level: -4dB (0dB=775mV) at 440Hz
  • Input Switching Noise: -100dB (IHF-A)
  • Delay Time: 1.8ms-11.5ms
  • Modulation Speed: 0.3Hz-7Hz
  • AC Adaptor: AC-90, VR-5
  • Current Draw: 10mA (DC 9V)
  • Weight: 490g (including battery)
  • Dimensions(mm): 79(W) x 57(H) x 136(D)

ICs, transistors and diodes used in the Pearl CH-02 Chorus:

CH-2 main circuit board:

  • IC1: JRC4558DD (dual operational amplifier)
  • IC2: MN3207 (1024 stage BBD)
  • IC3: MN3102 (BBD driver)
  • IC4: TL022CP (dual low-power general-purpose operational amplifier)
  • Q1,Q2,Q3: 2SC2240GR (NPN silicon transistors)
  • Q4,Q5: 2SC1815Y (NPN silicon transistors)
  • D1: 1S1588 (switching diode)
  • D2: UZ-5.1B (5.1V Zener diode)

SW-1 switching board:

  • IC1: MC14007UB (Three N-Channel and P-Channel complementary pair and inverter)
  • Q1,Q2: 2SC1815Y (NPN silicon transistors)
  • D1,D2: 1S1588 (switching diodes)
  • D3: Red LED
  • D4: MA522 (Lambda diode)

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