Recreating the OB-X "Tom Sawyer" Filter Sweep on a Dave Smith OB-6

Rush "Tom Sawyer" Oberheim Intro Recreated on Dave Smith OB-6 Synth

Published on Apr 18, 2016 infindebula

"Dave Smith did a respectable job making the OB-6. It's pretty versatile and it's got that Oberheim sound - mostly. Read the full description about why this video exists, or just sit back and watch while we recreate an iconic synth sound from scratch!

The opening sound in Rush's "Tom Sawyer" is created using a 1979 Oberheim OB-X in Unison mode. Unison means it's not just one voice going "PEEEOOOWWWWW", but all eight, which makes a really huge sound. The OB-X's analog filter envelopes have slightly different timing characteristics and decay curves on each voice, so the filter sweep happens at 8 subtly different rates. This imperfection creates a really huge, drippy sound, which is partly what's great about vintage Oberheim synths.

The OB-6 was unleashed in early 2016 by Dave Smith Instruments. It uses modern software-generated envelopes with identical timing for each voice. You can turn on Unison and detune the voices to thicken things up, but it won't have the timing slop needed to make this sound. In this video we make the patch using a single oscillator, set to produce the same pitch on all keys. Play six notes just sloppily enough to simulate the envelope timing variances, and people might think you're Geddy Lee! I think I got pretty close to the original sound. What do you think?

(I made this video to demonstrate that the OB-6 filter really can sound like an OB-X, and to share a creative workaround to imitate envelope timing slop. I did not buy the OB-6 with any desire to cover Rush tunes with it.)"