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.
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.
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).
Then, the signal goes back into the . This is the expander . Remember how we compressed the signal earlier? The expander does the opposite. It turns quiet signals down and loud signals up to restore your original dynamics.
On the schematic, trace the signal from the pre-emphasis filter. It goes into pin 1 or 16 of the NE570. This chip is brilliant because it contains both a rectifier (to measure the volume) and a gain cell (to turn it down). Here is the star of the show. The V3205SD is a 4096-stage BBD. The number "4096" matters. It means the maximum delay time is roughly half that of the old 1024-stage chips (like the MN3005), but it’s much quieter and easier to power.
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.
Mxr Carbon Copy Schematic Instant
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.
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
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). A BBD chip has a limited headroom
Then, the signal goes back into the . This is the expander . Remember how we compressed the signal earlier? The expander does the opposite. It turns quiet signals down and loud signals up to restore your original dynamics. Unlike digital delays (which use AD/DA converters), BBDs
On the schematic, trace the signal from the pre-emphasis filter. It goes into pin 1 or 16 of the NE570. This chip is brilliant because it contains both a rectifier (to measure the volume) and a gain cell (to turn it down). Here is the star of the show. The V3205SD is a 4096-stage BBD. The number "4096" matters. It means the maximum delay time is roughly half that of the old 1024-stage chips (like the MN3005), but it’s much quieter and easier to power.
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.