Jc-120 Schematic Direct
She started at the input jack—top left. A simple ¼" TS. Then a JFET transistor, 2SK117. She remembered her father’s journals now: “The first gain stage must be silent. No hiss. No prayer. Just the string.” The signal then split. That was the secret of the JC-120. Not one path, but two. The famous stereo chorus was born from a bucket-brigade device (BBD), the MN3002. A chip that literally passed voltage like a line of firefighters passing a bucket of water from input to output. The clock speed of that transfer created the shimmer—the microscopic delay that made the sound wider than a cathedral.
The JC-120 hummed. Then the chorus engaged. Two signals, slightly out of phase. One voice—hers—arriving a fraction of a second after the other. But her father’s modification, the red-ink change to the clock generator, had stretched that delay. Not to a slapback echo. To something else. The second voice arrived 2.7 seconds later. Then a third. Then a fourth. jc-120 schematic
Her father’s voice, buried in the tail of her own sentence, saying: “There. Now you can hear me when I’m not here.” She started at the input jack—top left
The BBD chips, starved of their proper clock voltage and given a new, erratic pulse, didn’t just delay the signal. They stacked it. Every word she spoke was repeated, but each repetition was degraded, filtered, darkened. After twelve repeats, her voice sounded like an old recording. After thirty, like a whisper from a tunnel. After a hundred, like static with a shape. She remembered her father’s journals now: “The first
She sat on the garage floor, listening to her own words decay into noise. And then, between the 127th and 128th repeat, she heard something else.
