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BiAge · 3rd July 2009

Hello,
this is my first post here and after reading this many posts about some OBs I have to comment:

OB-X voice-structure:
VCO: discrete
ENV: CEM3310
VCF: discrete (OTAs and OPs)
VCA: discrete (some OTAs and OPs)
VCA for Voice summery : discrete (OTas OPs), this VCA is for volume and
not on the voice-boards

OB-SX (all versions):
VCO: CEM3340
ENV: CEM3310
VCF: CEM3320 (2-pole)
VCA: discrete (CA 3080 OTA)
VCA for voice summery: discrete (OTA OPs)

OB-Xa (all versions):
VCO: CEM3340
ENV: CEM3310
VCF: CEM3320 (2x, one 2-pole, one 4-pole)
VCA: discrete (CA3080 OTA)
Summery-VCA: CEM3360

Additional information:
All versions of the OB-SX have the same voice-cards. There are only
differences in frontpanel, housing and presets. First units like OB-X, later like Xa and up to 56 presets.
The VCF-layout (OB-SX and OB-Xa 2-pole) is exactly the same.
In all OBs are some technical changes over the time. I have seen diff. colours and versions of PCBs with minor changes and there are some firmware-versions on the Xa.
So much confusion ? No !
The technical layout of the voice-cards in SX and Xa are very very near. The main difference is the second 4-pole-VCF of the Xa. The OB-X is much more different !

I hope this information is usefull for you. I collected the details after repairing (and using !!) many Oberheim-synths in good old germany.

BTW:
Some of the pictures here are made by myself and showing parts of my personal gear. It is no problem to take it from my website but it would be nice to mark them with the original source.

Thank you.

3rd July 2009	#35
BiAge Gear interested Joined: Jul 2009 Location: Germany Posts: 1	OB-X, OB-SX, OB-Xa Hello, this is my first post here and after reading this many posts about some OBs I have to comment: OB-X voice-structure: VCO: discrete ENV: CEM3310 VCF: discrete (OTAs and OPs) VCA: discrete (some OTAs and OPs) VCA for Voice summery : discrete (OTas OPs), this VCA is for volume and not on the voice-boards OB-SX (all versions): VCO: CEM3340 ENV: CEM3310 VCF: CEM3320 (2-pole) VCA: discrete (CA 3080 OTA) VCA for voice summery: discrete (OTA OPs) OB-Xa (all versions): VCO: CEM3340 ENV: CEM3310 VCF: CEM3320 (2x, one 2-pole, one 4-pole) VCA: discrete (CA3080 OTA) Summery-VCA: CEM3360 Additional information: All versions of the OB-SX have the same voice-cards. There are only differences in frontpanel, housing and presets. First units like OB-X, later like Xa and up to 56 presets. The VCF-layout (OB-SX and OB-Xa 2-pole) is exactly the same. In all OBs are some technical changes over the time. I have seen diff. colours and versions of PCBs with minor changes and there are some firmware-versions on the Xa. So much confusion ? No ! The technical layout of the voice-cards in SX and Xa are very very near. The main difference is the second 4-pole-VCF of the Xa. The OB-X is much more different ! I hope this information is usefull for you. I collected the details after repairing (and using !!) many Oberheim-synths in good old germany. BTW: Some of the pictures here are made by myself and showing parts of my personal gear. It is no problem to take it from my website but it would be nice to mark them with the original source. Thank you.