Oberheim • OB-Xa
The OB-Xa is a massive analog synthesizer with a very familiar and classic Oberheim sound. Its sound, size and power are very similar to the Prophet 5 from Sequential. However this one has up to 8 voices which can be split, layered and stored!
The OB-Xa was available in four, six or eight voice polyphonic models. They all featured patch memories, also in varying degrees. A minimum of 32 patches were available on early models (4 banks of 8). The maximum amount of patch memory storage found on many OB-Xa's is 120 patch memories. All models of OB-Xa, however, featured the new Curtis chips which offered great stability for an analog synth and they are attributed to its great filters and sounds.
The OB-X was very similar to the OB-Xa except that its voices could not be split or layered and it only had a 2-pole VCF filter. The OB-Xa features a better 4-pole filter with switchable 12 or 24dB/oct slopes thanks to the new Curtis chips. Splitting the keyboard mode separates the OB-Xa into two 4-voice synths with two available patches. The Layer mode plays the two patches simultaneously. There are also some added effect sources, perfect for any analog polysynth, including portamento, unison, sample & hold, chord memory and three LFO's!
However none of the original OB-Xa's have MIDI, unless otherwise having been modified. The OB-Xa is a classic and fat analog machine. It will give you thick analog pads and drones, punchy bass and cyclic analog effects. It's been used in the past by Depeche Mode, Van Halen (Jump!), Gary Numan, Jean Michel Jarre, New Order, Paul Sheafer, Prince, Queen, Jethro Tull, Stevie Nicks, Sneaker Pimps, Rush, Mike Oldfield, Richard Barbieri, the Thompson Twins and Bon Jovi.
played the OB-8 many times, and indeed XA is rawer/angry sounding. organic. don't mistake a synth in bad shape that drifts all over the place, with OBXA in full force.. 8 is slightly more polite and uniform. like a missing link btwn XA and XPander.
OBXA is the the only machine ever to feature a LP circuit based on SEM 12dB, yet built round CEM3320. once they got to OB-8 the circuit has changed from SVF - resonance doesnt "sing" or sting that way anymore. XA's 24dB filter is a separate circuit and not as good as 8's.
i use it for hi-reso, lo-cutoff voxy pads drones.. easy to get the VCAs to saturate/break... phenomenal sound. also i use it for vibrato brite strings w trademark "Curtis" sizzle
as w OBX, its not a bad idea to replace vco tune trimmers with multi-turns.
cheers
clusterchord
on van halens jump , not a obxa as in the video, definately superior to
any oberheim released after
Compared to OB8, oscilators drift alot and that make illusion that synth is rawer, but that 'gift' is not something I very much appreciated by OBXa.
Replacing it by OB8 resolved several key issues incl. important one reliability.
OBXa also lacks some important functions of OB8, so if choice is there opting for OB8 seems as clear choice.
I'm a little hesitant to just start jamming away at the trim pots because my OBXa is sweet as is...