Small Clone Chorus DIY Project with Four-Position Depth Mod

By Guitar Kit Builder
Dec 11, 2010
in Guitar Kit Builder - Pedals & Effects

The Electro-Harmonix Small Clone Chorus is an analog chorus pedal with depth and rate controls and an LED function indicator. To produce the chorus effect, the Small Clone bends the frequency slightly from the input source and mixes this altered signal with some direct unaffected signal. The combination produces a doubling effect. The Depth switch controls the amount of frequency change that occurs in the altered signal. The rate of alteration between raising and lowering the frequency is controlled by the Rate knob. The red LED indicates when the effect is switched on. The Small Clone is known for creating chorus effects ranging from Leslie-speaker type warbles to chiming 12-string tones. It became especially valued when it was used by guitarist Kurt Cobain on Nirvana's second album, Nevermind. You can hear it as the "watery" guitar sound on this track, Come As You Are:

You can create a kit to clone this pedal by visiting TonePad.com. There you will find the circuit, PC board design and sources for a ready-made circuit board and components list. The Small Clone circuit uses a 4558 general-purpose dual op-amp, an LM358 high-gain dual op-amp, an MN3007 low-noise bucket-brigade device and a CD4047 multivibrator. Here's a demonstration video of a do-it-yourself build of the clone.

The project shown above includes a four-position switch on the depth capacitor connected to the CD4007.