[sdiy] Mistake in Prophet T8 schematics? CEM3360 with -15V supply?

Tom Wiltshire tom at electricdruid.net
Sun Mar 31 15:48:16 CEST 2019


I’ve just been hunting through a few one schematics to see what supplies people have used with the CEM3360 dual VCA chip. This is a useful chip and not quite as big and complicated as its posher brother the CEM3330. But it’s weakness is that you can’t use it with +/-15V supplies. +/-12V is ok.

Most synths that used it with +15V reduced the negative voltage as suggested in the datasheet. MemoryMoog uses -7.5V, others mostly use -5V.

However, if you believe the Prophet T8 voice schematics, they’ve used -15V. I think this is an error. The main output board. Where another 3360 is used to control the output volume shows the chip running on +15/-5V, so I doubt the voice boards are different.

If anyone has the lid open on a Prophet T8 at some point, I’d appreciate a confirmation that there’s -5V on pin 7 and not -15V as per the schematic, just to know for sure.

Thanks!
Tom

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Synth & Stompbox DIY
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