Mxr Carbon Copy Schematic Apr 2026

The Carbon Copy’s modulation comes from a Low Frequency Oscillator (LFO) —usually a dual op-amp configured as a triangle wave generator. This LFO voltage is summed (added) to the "Delay" knob voltage. So, even if you don't touch the knob, the clock speed is subtly wobbling up and down. That wobble creates the pitch warble we call modulation. Section 4: The Output Stage & De-Emphasis After the BBD, the signal is a mess. It contains your delayed audio, but it’s a "staircase" waveform full of high-frequency clock noise (usually around 10kHz–30kHz). The first thing after the BBD is a low-pass filter (the reconstruction filter). This smooths the steps back into a sine wave and kills the clock whine.

Unlike digital delays (which use AD/DA converters), BBDs sample the audio voltage and pass it down a chain of "buckets" (capacitors) at a specific clock rate. The faster the clock, the shorter the delay. The slower the clock, the longer (but dirtier) the delay. Mxr Carbon Copy Schematic

However, the magic happens right after the buffer. You will see a network of capacitors and resistors that form a (a high-pass shelf). The Carbon Copy deliberately cuts bass and boosts treble before the delay chip. The Carbon Copy’s modulation comes from a Low

The delayed (and compressed/expanded/filtered) signal goes through the . This is a simple voltage divider. When the Mix is at noon, you have equal parts dry and wet. When it’s maxed, you have only the wet signal (great for using the pedal as a weird vibrato unit). That wobble creates the pitch warble we call modulation

A BBD chip has a limited headroom. If you hit it with a hard pick attack, it will clip into ugly, splatty distortion. The compressor gently squashes your dynamics so the BBD sees a consistently strong, but not too strong, signal.