Oberheim SEM

Oberheim SEM Image

The SEM was Oberheim's first official analog synthesizer. SEM stands for Synthesizer Expander Module. It was conceived with the notion of being used as a backup synth connected to a sequencer for layering or beefing up your existing monophonic analog synths. The SEM itself was a keyboard-less module with two analog oscillators, a 2-pole multimode filter, ADR envelopes, and an LFO. Each of the two oscillators offer triangle or rectangular waveforms. But unlike the Moog and ARP counterparts of the time, the SEM's 2-pole (12dB/oct) filter was a little thin. The others used a 4-pole (24dB/oct) filter which has a steeper roll-off and so it sounds much better. But the SEM's filter offered many modes in addition to low-pass, including high-pass, band-pass and band-reject.

Although SEM modules and other external controllers could be inter-connected, the SEM is not a patchable synth module like other modular type synths of the time. Its signal routing was more or less, hard-wired. The SEM was for all purposes, an accessory. But Oberheim jumped into the synth market by coupling SEMs with a keyboard and an analog sequencer into a compact, white, little performance synth. That led to the Two Voice, Four Voice and Eight Voice models. And from there, came the rest of Oberheim's history of instruments. Some earlier SEMs have several differences in their circuit design that affects the envelopes, filter, etc. If your SEM has "1080" written inside, it's an early one. If you see "1180", it's the "normal" one that most people know and love.

Oberheim SEM Image

Pictured just above is the Polyphonic Synthesizer Programmer, introduced in 1976. It could be used with the SEM and the Two-, Four-, and Eight-Voice models. The unique feature this programmer had (for its time) was the ability to store the knob settings of a SEM modules parameters. Neither Moog nor ARP could offer memory/patch storage like this at the time. The PSP could accommodate up to 8 SEMs or, in other words, the Eight Voice. SEMs have been used by Jan Hammer, Josef Zawinul, and filmaker/composer John Carpenter.

Lookup Oberheim SEM Prices

The link above will take you to an eBay search for this synth to see active listings with more images, specs and information. If you don't find it there, try looking in our forum marketplace. Our marketplace gets thousands of visits every week so make sure to check back often if you want to buy or sell a synth.

Related forum topics

Comments

Are you looking to buy or sell a Oberheim SEM? Post an ad in Gear For Sale or a request in Gear Wanted. For spare parts and repair services check out Gear Services & Other Goods. Our forums also has a Buyer’s Guide section where you can ask for advice on buying synthesizers.

17 Visitor comments
Reivaj
December 2, 2013 @ 3:12 pm
The filter is really unique, doesn't thin out the bass freqs when you increase the rez the way Moog and SCI (CEM) filters do, the SEM is way less dramatic and more gradual at this.
Oh! And the LFO is SineWave, wich I love and quite nice for processing external sounds with the UniVibe-esque fx you can get with the Notch Filter. It goes into low freq audio rate.
I'm rediscovering synths with the SEM Pro, in these instruments subtle pot editing is very rewarding, you don't need a dozen of elements to make a gorgeous and lively dinamic sound.
Add a touch of verb/delay and you're golden.
8-)
Reivaj
December 2, 2013 @ 2:56 pm
I've had a new SEM Pro for about a year and I love it.
It sounds the way I believe an analog synth should: Vangelis, Giorgio Moroder, Depeche Mode, Portishead/Drokk... From Tangerin Dream to Faithless' trance (these 2 VCOs don't need to be multiplicated/supersaw style, no way as much as VAs do).
Always with buttery smoothness, subtetly and sheer power.
The VCOs, PWM & Sync sounds are to die for.
Lasse
August 13, 2013 @ 9:31 am
"The others used a 4-pole (24dB/oct) filter which has a steeper roll-off and so it sounds much better."

That's a ridiculous statement. Yes, many of the most famous filter designs are 4-pole, but saying that they sound "much better" is just silly. A 2-pole filter can sound amazing in its own right and may very well be the better choice for certain sounds. It all depends on what sound you're after. It's like saying apples taste better than oranges.
Reivaj
August 10, 2013 @ 8:52 pm
Saying that 4Pole LPF sound so much better than SEM's filter is plain ridiculous.
The filter on the SEM is magical and perfect in its own right.
MangoCherry
July 12, 2013 @ 10:44 am
If you want to know how this sounds, listen to the Drokk LP. Almost entirely created on various SEM setups.
 
Post Comment!
VSE Rating

It’s Good

User Rating

Rated 4.28 (258 Votes)

  • Check Price
  • The link above will take you to an eBay search for this synth to see active listings. If you don't find it there, try looking in our forum marketplace or post a wanted classified.
  • Specifications
  • Polyphony - Monophonic
  • Oscillators - 2 VCO's (each with sawtooth or variable-pulse waveforms)
  • LFO - LFO is triangle wave only
  • Filter - 2-pole multimode (low-, band-, hi-pass, band-reject) VCF with ASR (Attack, Decay and Sustain) generator
  • VCA - 2 ADR (Attack, Decay and Sustain) Envelope Generators
  • Keyboard - None
  • Effects - None
  • Memory - Not on-board. External Polyphonic Synthesizer Programmer module stores control voltage settings for up to 8 SEM modules each.
  • Arpeg/Seq - Not on-board. External DS-2 Digital Sequencer option.
  • Control - CV / Gate
  • Date Produced - 1974 - 1979

Errors or Corrections? Send them here.