This last, which gave the White Face its distinctive sound, was a bone of contention & apparently led to legal wrangling. It is a sealed (potted) module, hiding a guilty secret, or so the story goes.

A copy of the Moog ladder filter, also used in early 2600s. After discovery, this was replaced by an exclusive ARP circuit, incorporating a design flaw. It can not cover the entire audio range, with a high of only 12 K/Cs. Thus the later version, identified by a black control panel ( hence 'Black Face'), has a different, less biting, sound.

This is probably just a story, the white faces we have seen have a 4023 filter module. This is a 2 pole OTA type, similiar to that used later by Oberheim. The 4 pole ladder modules are numbered 4012 & later 4034 or 4035. These appeared in early 2600 models & some later 'Black Faces'. These were discontinued for legal reasons.

Both versions have a distinctive black vinyl wrap around base. This extends forwards, offering some protection to the protruding organ style keys. Lack of this feature is a weakness of the Mark 2 model. A steel case with hinged control panel & mock leather sides. Entirely plastic keys extend beyond the front & are often broken. 'Proportional' buttons allow pitch bend.

This neat black face is unusual, a factory hybrid. Innards & contacts are Mark 2.

With 'proportional controllers', seen on the front left & rear CV / Gate jacks.

Case & keyboard are the better Mark 1 type.

The company founded by Alan R. Pearlman produced a number of classics over the years. Also a few that missed the category. Their last design, the Chroma, survived the company's demise & was eventually built by Rhodes under their name.

More will be on this page soon.