: Unlike most amps that sum stereo signals to mono at the speaker, the JC-120 sends the dry signal to one 12-inch speaker and the pitch-modulated signal to the other. This creates a "spatial" chorus effect that mixes in the air, not in the wires. Bucket Brigade Devices (BBD)
A spring reverb tank typically driven by BJT (Bipolar Junction Transistor) drivers with current feedback. 4. Historical Revisions The schematic has evolved through several "editions": Key Changes Early (1970s) Discrete components, heavy chassis, toggle power switch. Mid (1980s) Introduction of the (head version) with revised OpAmp circuitry. Modern (UT/JT) jc-120 schematic
Print it out. Keep a highlighter nearby. Trace the audio path from the input jack to the speaker terminals. Once you understand why Roland placed a 330pF cap across the feedback loop of IC1B, you will understand why no modeler has fully captured the 3D depth of a real Jazz Chorus. : Unlike most amps that sum stereo signals
Understanding the schematic of a Roland JC-120 Jazz Chorus is like studying a map of modern guitar history Modern (UT/JT) Print it out
Roland JC-120 Jazz Chorus Go to product viewer dialog for this item.
When looking at the schematic, pay close attention to the in the power supply section, as these are the most common failure points in older units, leading to excessive hum. Additionally, the Chorus/Vibrato selector switch often requires cleaning or replacement if the effect fails to engage.