The MEMX-REVX mod for the Lexicon PCM42 extends the maximum delay of the machine to 19.2 seconds, and provides reverse playback in either a ‘one-shot’ or ‘continuous’ mode. This modification was designed and implemented by Gary Hall, the original designer of the PCM42.
This package consists of one MEMX-REVX PC board (with included 256k x 1 bit DRAM), 6 additional DRAM ICs (to replace stock memory), a three position switch, male headers, and an instruction set for specific modifications which will need to be performed on the PCM42. Technical experience necessary for this project include: soldering/desoldering, removal and installation of ICs, cutting traces, jumpering wires to re-route signal and drilling into the chassis for installation of a reverse mode switch.
After the modification, the PCM42 will be able to hold nearly 20 seconds of delay. Because of the limit of digits, the display will show ¼ of the actual time of delay. The reverse delay feature allows the user to reverse content in two different modes. The ‘one-shot’ features one period of delay played backwards, with standard delay continued. With feedback control turned up, the result is the delayed content being continued throughout the decay time. The ‘continuous’ mode continuously reverses the incoming signal. With the feedback turned up, this results in the user’s original content being reversed and fed back into the delay to get flipped again. Hence, the original content will play back normally every other time - depending upon long the feedback decay is set.