Thursday, February 18, 2010

Oberheim Synthesizer Expander Module, Contemporary Keyboard 1976

Oberheim Synthesizer Expander Module (SEM) from page 17 of Contemporary Keyboard Magazine November/December 1976.

This ad ran only a handful of times in CK magazine with the last appearance I could find occurring in September 1977.

As mentioned in my previous blog post, I'm kind of playing catch-up with older Oberheim ads, mostly because of my inexperience with their early polyphonic systems. But this ad strips the system down to the 'basic component' - the Synthesizer Expander Module, aka SEM. And I've always loved the SEM. has an SEM page with a bit of tech info if you want to learn more about the module, but basically the SEM was a keyboard-less monophonic synthesizer module, used to beef up the sound of other manufacturer's synthesizers. I always loved the sound of the SEM - and I can still recall the first time I heard one in my friend's basement. That same basement where I came across many of my first synthesizer catalogues and a certain someone's custom built modular synthesizer.

More importantly though, The SEM was also the building block to begin your journey to creating a polyphonic Two-, Four- and Eight-voice system. And as mentioned in the ad, if you already had one SEM and were ready to take the polyphonic plunge - no problem - you could even buy the entry-level Two-Voice system with only one SEM installed, so you could pop your SEM right in next to it.

According to's Two-Voice page, the original Oberheim Two-Voice started out as an incomplete Four-Voice with two SEM modules missing. The 'fixed-configuration' Two-Voice, as seen in the ad photo, didn't make it into production until 1976.

End note: I know I mentioned it before in a blog post I wrote about Oberheim's Ten Year Anniversary advertisement from 1980, but I thought I would expand a bit on Tom Oberheim's jump back into the synth business by reissuing his SEM module. To quote from his Web site:
"The new SEM is pretty much the same as the original, that is to say 100% analog! True voltage controlled oscillators, the classic SEM multi-mode filter, analog VCA, analog envelope generators and LFO. Did I say it is 100% analog? In fact, I made the circuitry as close to the original as possible."
According to the Web site, a new SEM module, with midi-cv conversion, goes for $899.00 US. This ad tells us that an SEM in 1976 went for $695 - that converts to approximately $2200.00 US today.

Not a bad deal - time to pick one up! :o)

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