Hi Oberheim people. Just kidding, I read tons of post about Tom Sawyer OB-X sound. Well, I’m not a fan of Rush, but this is not related with the Big question: Does Obsession’s sound and Arturia OB-Xa sound are the same of the real beast?
Brief answer: NO, but they aren’t so far. The firs thing to understand is the damn difference SEM/OB-X and OB-Xa and its “brother” OB-8 (my favorite one), focusing only the differences in sound.
The classic Oberheim sound is the giant S.E.M. Up to eight voices generated by totally independent modules, one per voice. This huge independence is great for multi timbrical, not for a compact poly-synth. The filter circuit of the S.E.M. is discrete components based, it’s a 12db/oct two poles low pass. So, what is the point? Try play a SEM (or a OB-1 or a OB-X) with very high resonance value: Volume, especially in bass notes will not decreased, still sounding “punchy”. You can’t do the same with a MiniMoog, for example. With high resonance you’ve got a “thin” sound and a high volume decrease. This is behavior of the ladder filter, the 24db/oct installed in the Prophet series, all the Moog production, and partially in the sons of the OB-X. In the OB-Xa, the filter is switchable in two tastes: 12 and 24db/oct. Please note, when you set the OB-Xa to 12db/oct, you have NOT the same circuit configuration of the OB-X, cause the CEM integrated circuit works in another mode. How the filter sounds is the core of the debate.
Brief conclusion: When in real OB-Xa you set the filter to 12, you have a 12db/oct filter, but not the same of the OB-X.
If the Obsession is a OB-X emulation (like most think) well, there is something weird.
Why a 12/24 switch on a OB-X emulation? There is no such switch on real OB-8, it can’t run at 24db/oct. So, is it maybe a both OB-X + OB-Xa emulator? Synapse Audio is unclear about, only saying: “Very deep, realistic emulation of an analog polyphonic synth”. I can think it’s a emulation of the JP-8 or the CS-80? Of course no, but (IMHO):
No one can affirm Obsession is a pure OB-X emulation.
It’s somewhat an emulator of the entire OB series.
At least, Arturia labelled it’s version OB-Xa V, avoiding any mismatch.
I apologize for the messed up post.