Welcome to the Buchla & Tiptop Audio 200 series project. In this project Buchla has teamed up with Tiptop Audio to resume the production of Don Buchla’s 200 series and convert it to Eurorack standards. These extremely rare pieces of equipment made almost half a century ago will once again be available, and this time to a wide audience. Each module will be produced separately as production schedules and component availability allows.
The TipTop Audio Buchla 285t Frequency Shifter is an interesting module for processing audio samples or live voice input via a microphone through the 207t Mixer/Preamplifier module. The "sum" and "difference" outputs from the 285t can then be routed to the 292t Quad Lopass Gate, creating dynamic tone shaping. By further splitting the processed signals into the left and right channels, this setup allows for a rich stereophonic effect.
FREQUENCY SHIFTER
The Frequency Shifter receives and external audio at its "signal" input then shifts it with either its internal oscillator "INT" or with an external oscillator at the "ref." input. There is a switch to choose either INT or ref. The INT oscillator frequency goes from 0 to 1kc. The CV input is sent to the INT oscillator only and can be varied with its attenuverter. FM receives an audio input and can be applied to INT. The amount of modulation is determined by the attenuator knob. The resulting shifts are present at the "difference" and "sums" outputs. There are two identical outputs for each of these.
BALANCED MODULATOR
The Balanced Modulator receives an audio signal at the "signal" input. This can be thought of as the carrier while the "ref." input receives a different audio signal (the modulator). The CV input and its attenuverter modulates the sweep from "zero-amplitude-ring." The "ring" double output is a pure ring modulation determined by the incoming signal and ref. The bottom MODULATION section applies to the "variable" double output. The amplitude knob manually sweeps from zero (the pure incoming "signal") through amplitude modulation ending in pure ring modulation. When this knob is set fully CW to "ring" it is the same signal as the "ring" outputs.
