Circuit Overview:
A great source of 70's string sounds the Performer uses the Mostek MK50240N as a top octave synthesizer. 12 TDA1008's are used to create a logical tonal grid according to which keys are being hit on the brass, and 8' and 16' violin mixes. From there on it's a pretty straightforward analog filter/envelope on the brass and EQ and analog delay for the string section. I see there is a performer version 2 which adds an octave switch in the middle. I recently got one and set up the filter with the resonance mod and someone had already run the tuning shaft out the front so you don't have to reach around back to tune it. Serials on my units are B04168 (A version 2), B01868 and A320, the latter of which has a totally different Early Brass Board. As you can see there is a ladder filter on that one rather than the SSM unit. So probably it's a typical Crumar thing where they made an initial run of a small number then made some redesigns and punched out a larger number. I couldn't discern other differences except I think they used Tantalum capacitors for the envelopes in the early one like the ARP Omni, then went with regular electrolytics in the later ones I think. (PS 11/23/07 I worked over a beautiful #A840 which also has the ladder filter so apparently the "A" versions all had this? My numerical estimate of how many were made above is based on a statistical evaluation of the serial's I've observed. I figure maybe a thousand to two of the first version. 5 or 6000 of the second version. )
Service Tips:
No Brass out main mix? Don't forget there's a shorting jack on the brass out. If it's dirty no brass signal gets to main out. The TOS board is under the keyboard, as are the TDA1008's. I had power supply problems with mine when I got it. Bad regulator or like that. Another with
your standard tantalum capacitor shorted before -24V regulator. Also Sliders commonly break off. Using a wire guage bit of appropriate size, I drilled two holes; one near each 'edge' of the plastic face that broke off, and I used JB weld and copper wire to form a 'loop' of metal adhesed into place there. Then I put on a conventional slider cap and it works great!
Parts:
I don't know where to find exact slider caps for these, or pots as noted above. In fact I see that there are two different types of slider shafts and knobs and they are NOT compatible. The fatter ones will fly off and hit you in the eye if you try to put them on the shaft for the slightly skinnier ones. They look very similar but they aren't compatible. Most other parts I have in stock or can be found doing google searches or on ebay. Contact me if you need anything.
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