> tech specs
• CV-IN The RS90 generates a particularly wide range of frequencies. The minimum - approximately 0.3Hz - is well into the subsonic range, so the RS90 will double as an LFO when required. This architecture emulates that of the Minimoog and larger Moog modular synthesisers such as the IIIC and System 55. At the upper end of the scale, the RS90 will reach frequencies of approximately 17kHz, which is at the top end of hi-fi reproduction, and beyond many peoples' upper limit of hearing. The primary method of controlling the pitch is by applying a suitable CV to the CV IN socket. This respond correctly to the 1V/oct standard adopted by Moog, ARP, Roland and Sequential Circuits (among others). It will not allow you to play conventional melodies if you apply a CV conforming to the Hz/Volt standard used by Yamaha and most Korg monosynths. Before leaving the factory, every RS90 is calibrated to respond linearly to input control voltages ranging from -10V to +10V. This gives the RS90 a theoretical audio range of 20 octaves. In practice, the range is closer to a "mere" 16 octaves - still far exceeding the capabilities of most other manufacturers' devices. FREQUENCY The frequency knob has three ranges:  WIDE Turning the FREQUENCY control from its minimum to its maximum will cause the RS90 to produce its full range of frequencies from 0.3Hz to 17kHz.  "0" The FREQUENCY control allows you to tune the RS90 by approximately a fifth (7 semitones). Slight detuning of one of a pair of RS90s produces a much thicker sound than would be obtained if both oscillators were in tune with each other. More radical tunings - such as fundamental with added third and fifth - offer a range of conventional 'synth' sounds.  "-2 OCT" This reduces the pitch of the RS90 two octaves with respect to "0", but in all other respects the oscillator's operation is identical to the "0" mode.  CV-IN VARY The CV-IN VARY socket and its associated LEVEL control allow you to specify the oscillator's sensitivity to pitch CV within the range ×V/oct to approximately 0.4V/oct. The former of these makes the oscillator invariant to incoming CVs, while the latter makes it over-sensitive compared to CV-IN. This is particularly useful when using an RS90 as a 'sync' oscillator because it then becomes harmonically unrelated to the audio oscillator, thus generating a different timbre on each note that you play.  PULSE WAVE The pulse wave output can be adjusted from 0% (leading pulse) through square wave to 0% (trailing pulse) as you turn the PULSE SHAPE control from its fully anticlockwise position through to its most clockwise position. As factory calibrated, the square wave shape will be obtained when the knob is at "12 o'clock". You can also influence the pulse wave shape by applying a CV to the CV-IN SHAPE socket next to the PULSE SHAPE control, as follows:  A CV of +2.5V will generate a 0% leading pulse wave;  A CV of 0V will generate a square wave;  A CV of -2.5V will generate a 0% trailing pulse wave. The output from the SQR-OUT socket is approximately ±5V.  SAWTOOTH/TRIANGLE The sawtooth wave output can be adjusted from a falling sawtooth through a triangle wave to a rising sawtooth waveform as you turn the SAWTOOTH SHAPE control from its fully anticlockwise position through to its most clockwise position. As factory calibrated, the triangle shape will be obtained when the knob is at "12 o'clock". You can also influence the sawtooth wave shape by applying a CV to the CV-IN SHAPE socket next to the SAWTOOTH SHAPE control, as follows:  A CV of +2.0V will generate a falling sawtooth wave;  A CV of 0V will generate a triangle wave;  A CV of -2.0V will generate a rising sawtooth wave. The output from the SAW-OUT socket is -2V to +8V when a true sawtooth wave is produced, and ±2.5V when a triangle wave is produced.