MATRIXSYNTH: JCS BN-1 "Bakery of Noise" Digital PCM Synthesizer – One of a Kind

Saturday, April 06, 2024

JCS BN-1 "Bakery of Noise" Digital PCM Synthesizer – One of a Kind

Note: Auction links are affiliate links for which the site may be compensated. "JCS BN-1" 4-Bit Linear PCM Synthesizer - Part 1 (Prototype)

video upload by blarrer20

"JCS BN-1" 4-Bit Linear PCM Synthesizer - Part 2 (Finished)

video upload by blarrer20

"This video demonstrates the final version of a 4-bit Linear PCM synthesizer that I have designed and built over about two months. It makes use of mostly Soviet clones of 7400 and 74LS series TTL chips, with no microcontrollers involved. It has a 256 x 4 SRAM chip that allows the user to program whatever waveforms may be desired, with looping capability, and starting at whatever point desired. Most importantly, it is able to be controlled by an external source, for example a keyboard instrument. It also has a frequency doubler circuit. This video is part 2 of 2, showing the finished product.

If you want to skip right to the sounds, go to 27:08"

via this listing

Pics of the inside below.

Details from the listing:

"For sale is a one-of-a-kind rudimentary digital synthesizer that I designed and built in 2015 at age 18. This "Bakery of Noise" uses linear PCM sound generation with 4-bit sample width and the unusual feature of allowing the sampling clock to be derived from an external frequency source, such as an arbitrary musical instrument (so long as its output is at least ~0.12V RMS). It contains memory for 512 samples, half of which are stored in SRAM (which is programmed in binary using the front panel switches, much like early computers such as the Altair 8800), and the other half in ROM. The number zero, when written as a sample value, can be used to set a loop point, allowing periodic sample patterns of arbitrary length up to 256 samples.

Note that, when used with external input, the output's fundamental frequency is a sub-harmonic of the input frequency or its double, making possible some very interesting combined tones similar to the Maestro W-1. In run mode, the address switches determine where the sample count begins, allowing the ratio of the output and input frequencies to be changed on the fly; this can produce really complex and interesting effects. There is also an interesting (unintentional) feature to mention: the external input signal slightly affects the internal clock, giving complex patterns of interference.

The BN-1's sound depends significantly on the programmed series of samples being used and the clock source selected. No matter what, the sound tends to be "raw" and "digital" (like early sound chips), because the design incorporates no subtractive filtering and no automatic amplitude control, and the 4-bit sample width makes for large steps between adjacent amplitude levels. It is thus an instrument best suited to lo-fi / noise / experimental music, though it can be used for beautiful and mellow things with care and tone shaping.

Note that the SRAM is volatile, meaning it loses its memory when power is turned off. The unit could be modified to have battery backup rather easily, but I hate batteries, so I haven't done it.

This unit was designed repairability in mind. All components are through-hole, and all ICs are socketed for easy replacement. The design most closely resembles IC-based digital circuitry of the late '60s through early '80s.


1/4" jacks for input and output
Level controls for input and output
3 clock sources: internal oscillator, external input, and frequency-doubled external input (minimum input level for both external options is approximately 0.12V RMS)
Internal clock frequency control
8 Address Entry switches for selecting the current programming address (in Program mode) or the address that the counter starts at (in Run mode)
4 Data Entry switches for entering data to be written to RAM in Program mode
Count / address reset button
RAM write button
ROM / RAM memory switch
Program / Run mode switch
Loop Enable switch
Input voltage: 9 to 12 V DC, tip positive
More information about the BN-1, including full schematics and circuit descriptions, can be found on my website.

The physical device itself is in excellent cosmetic condition, having been handled with care and stored in clean and dry conditions throughout its existence. It is functioning perfectly, and has plenty of life ahead of it.

You may wonder why I am selling this unique and personal piece. As much as I've enjoyed using it over the years, my tastes and interests have shifted, and I am saving up for a house (and, of course, other projects). Thus, I've decided it would be best to sell it to someone who will really enjoy and appreciate it.

Thanks for looking, and feel free to ask questions or make an offer!"

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