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Sunday, August 7th, 2022 09:39 am

Synth Glossary

A low-pass filter filters out higher frequencies from the sound....


"The OB-1 was the first programmable monophonic synth, blessed with eight patch memories. For that alone, the little Obie deserves its place, but in fact this is also an unusual, interesting-sounding instrument, smartly turned out and very easy to use. "In both audio and features, the OB-1 is not a million miles away from Oberheim's SEM design, used on the company's modular 2-Voice, 4-Voice and 8-Voice instruments. Not in any way as gob-smackingly powerful as a Moog, the instrument was designed more as an add-to, like something you'd play alongside a Moog or an ARP. In fact, one of the OB-1's original purposes was as a sound source for 30 Systems' Slavedriver guitar interface. (In the 1970's, Oberheim thought of itself as more of an accessories company that an instrument builder.)

"Two VCOs can play through a five-octave range, callibrated in semitones. A fine-tune control is continually variable through an octave. Alongside these on the VCO panel is Oberheim's curious but effective method of waveform selection, comprising a "pulse type/saw type" switch and rotary-controlled waveform shaper that ranges either from square to narrow pulse or from triangle to sawtooth. Both VCOs have this facility, and in the middle of their respective panels, is a sync switch for lashing the oscillators together. The VCO panel wraps up with a sub-oscillator option that can add in a subharmonic square wave to the signal flowing out to the filter. There is no oscillator balance control as such, just a -3 dB (one-half volume_ cut option on each oscillator. Cross-mod, for frequency modulation by VCO2, is available as a simple switch on VCO1.

"Filtering is switchable two-pole or four-pole, with frequency cutoff and resonance controls, and the filter cutoff can be driven by either the LFO or the ADSR envelope generator. Keyboard tracking is available, though it's simply on or off. The VCF has its own dedicated ADSR envelope generator. A separate set of controls services the VCA. "At the top left-hand side of the control panel are eight program memory buttons, plus a manual mode button. Typically large, Oberheim control knobs govern an LFO delay factor and LFO rate. A three-position switch gives you the choice of square, sine or sample-and-hold LFO waveforms.

"Under the panel heading of "keyboard," com a portamento knob (governing amount), and octave transpose switch and a VCF control that lets you manually vary the VCF cutoff point. A flipper-type pitch bend control can bend VCO2 or both oscillators up or down in narrow or broad ranges. The same flipper activates LFO modulation and, curiously enough, noise.

"Without going overboard, you should be able to drum up most of the classic analog synth sounds or sound effects. The sync option gives you plenty of intensity, rather than in-your-face power, and cross-mod introduces nice, unpredictable, metallic or "belly" overtones. Good filter options plus noise and portamento complete what can only be described as a full package of programming parameters. And here's the killer punch of the OB-1: You can set up and store your creations -- something that very few genuine vintage monophonics allow you to do."

The OB-1 also features cv/gate in and out, good lefthand controller lever, 2 oscillators plus a noise generator, an ADSR envelope generator (as opposed to the SEM's ADS).

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