Tiptop Audio / Buchla 285t Frequency Shifter

The FREQUENCY SHIFTER MODEL 285t is a module combining two independent functional sets: an upper section with frequency shift capability and a lower section supporting both balanced modulation and ring modulation.

Each function features extensive CV inputs, dedicated output jacks, and individual controls, enabling musical control over all parameters.

Features
Frequency Shifter
This section has two inputs. Typically, an audio signal is fed into the Signal input, and its frequency is compared to the internal reference oscillator. The sum and difference frequencies of these two inputs are then output separately.
Typically, a sine wave without harmonics is used for the reference (ref.) input. Therefore, the 285t includes a built-in reference oscillator that outputs a sine wave. This oscillator can be switched to an external signal input via the ref. switch. The internal oscillator is also CV-modulatable: the Control input accepts exponential FM, while the F.M. input accepts linear FM.
Signals entering the Signal input are output with their frequency either added to or subtracted from the reference oscillator's frequency. The Difference output provides the subtracted signal, while the Sum output provides only the added signal.

Balanced Modulator
This section similarly has two inputs. The Signal input serves as the carrier signal, and the Ref. input serves as the modulator signal.
The Ring output, like a typical ring modulator, outputs the sum and difference of the input signals, completely canceling the carrier signal.
The Variable output provides variable modulation depth. It crossfades between the carrier signal and the ring-modulated signal based on the CV signal input to the Amplitude knob or Control CV input.

Frequency Shift and Pitch Shift Balanced Modulator
While the terms “pitch” and ‘frequency’ share similar definitions, the effect of a frequency shifter resembles that of a ring modulator. A pitch shifter produces a more “musical” effect by preserving the relative harmonic relationships within the input signal. In contrast, frequency shifters like the 285t uniformly add or subtract frequency from all elements of the input signal.
Consequently, the more harmonics present in the input signal, the more the original harmonic relationships are disrupted when frequency shift is applied. This alters the interval relationships of the original input signal, creating distinctive sonic effects unattainable with other effects.

About the Buchla & Tiptop Audio “Eurorack 200 Series”
The “Eurorack 200” series is born from the collaboration between the legendary West Coast synthesizer manufacturer ‘Buchla’ and Tiptop Audio. It reproduces the extremely rare modular synthesizer “200 Series,” developed nearly half a century ago, in Eurorack format. Bringing the essence of West Coast synthesis—Buchla modules—to today's modular players. The Eurorack 200 Series breathes West Coast spirit into your modular system.

Width: 16HP
Depth: 45mm
Current Consumption: +12V: 50mA
-12V: 44mA