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Review: Dave Smith Instruments OB-6

August 3, 2016

At last January’s NAMM show, a major buzz surrounded the OB-6, the product of collaboration between pioneering synth designers Tom Oberheim and Dave Smith. Tom and Dave, friendly rivals in the 1970s at the dawn of polyphonic synthesis, had recently worked on a joint project to produce an instrument combining their considerable talents. Faced with long lines at the NAMM booth where the two men appeared together, I had only a few minutes to don headphones and check out the OB-6, but my first impression was that they had gotten it right. It definitely felt and sounded like an Oberheim, and I’ve owned six different models.

Fig. 1. The OB-6 6-voice, all-analog subtractive synthesizer is a joint project from Dave Smith and Tom Oberheim.
The OB-6 is a 6-voice subtractive synthesizer with a 49-note keyboard that senses velocity and aftertouch. Each voice has two audio oscillators, a suboscillator, a variable-state filter, a white noise generator, two ADSR envelope generators, and an LFO. The entire audio signal path is completely analog. It also has two multi-effects processors, an arpeggiator, and a polyphonic step sequencer. Along with storage for a thousand programs, the OB-6 has a manual mode that lets you switch off preset memory and rely entirely on the front-panel controls to sculpt your sound in real time, just like in the old days.


The OB-6 looks very much like other Dave Smith Instruments products, with real wood side panels and a black-coated steel exterior. At first glace, it would be easy to mistake it for another recent DSI synth, the Sequential Prophet- 6, and the similarities don’t end there. One visual cue sets it apart, however: Blue horizontal pinstripes recall the classic Oberheim OB-8 and OB-Xa. Like the Prophet-6, the OB-6’s only dedicated left-hand controllers are wheels for pitch bend and modulation (LFO depth only), and the front panel contains lots of knobs and buttons organized into functional sections. The largest of five alphanumeric LED readouts displays the current program number in three digits. The OB-6 has no LCD, which means no menus to dive into and no program names displayed.

A class-compliant USB Type-B connector and MIDI In, Out, and Thru on 5-pin DIN connectors handle MIDI data flowing to and from the OB-6. Also on the back are three 1/4-inch audio outputs for unbalanced left and right signals and stereo headphones, as well as four control jacks: one for a sustain footswitch, one for a footswitch to start and stop sequencer playback, another for an expression pedal controlling volume, and a fourth for an expression pedal controlling filter frequency. Although they’re all logical choices, I wish I could assign at least one expression pedal to control a user-defined parameter.


The oscillators, filter, and amplifier for each voice are voltage controlled, just as they were in classic Oberheims such as the TVS-1 and Matrix-12. Each voice has four sound sources labeled VCO 1, VCO 2, Noise, and Sub Octave, which generates a square wave 12 semitones below VCO 1’s pitch. You control their levels with four knobs in the Mixer section. Once you’ve run the calibration procedure a few times, the oscillators stay in tune as long as the ambient temperature doesn’t change drastically—quite impressive for any analog synth.

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