Mxr Carbon Copy Schematic __hot__ Jun 2026

BBDs are noisy. They introduce clock noise and hiss. Also, they have a limited bandwidth. By boosting the highs going into the delay, the signal-to-noise ratio improves. When we later cut those highs on the output (de-emphasis), we also cut the hiss. This is the same trick used in analog tape noise reduction (Dolby).

Static buildup from plugging/unplugging cables can destroy the surface-mount (SMD) FETs responsible for switching. Affected Components: In Revision C boards, transistors Q10, Q11, Q12, and Q13 Mxr Carbon Copy Schematic

Crucially , this stage also contains the (the opposite of the input pre-emphasis). It cuts the highs back down to normal, simultaneously removing the hiss we were worried about earlier. BBDs are noisy