703e VCF with LM13700s

Someone asked on electro-music about subbing a LM13700 for a couple of CA3080s in a Roland-style filter, so I thought I’d have a go. I levered out the 3080s in my 703e clone and wired up three LM13700s (two for the four poles, one-half for the resonance control) and to no-one’s great surprise, it works.

Here is some quick fiddling with an out-of-tune clone 700 oscillator into the 703e VCF.

It sounds a bit overdriven to me – I was trying to avoid any red lights, but being in a hurry to get something down it’s possible I got something wrong along the way.

Now I think about it, it could be that I didn’t recalibrate the DC offset trimmers from when it was set up with the 3080s.

The wires strewn all over the board probably aren’t helping either, so I’m tempted to build up another 703e and make some LM13700-to-CA3080 adaptors to test this further.

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i’d rather multiple jack

710 multiple clone

OK I know, but it’s a start.

3mm acrylic is bendy, so I reinforced the back with 1.5mm aluminium to make it much stiffer, but it’s still not as solid as I’d like it.

Clone System 700 multiple from the back, showing the metal reinforcement

I should have really made the metal plate wider than I needed on one side, and bent it up to form an L-shape to totally stop the bending.

No chance for recessed jack sockets like on the original, my metal working just isn’t that good. 4.5mm panel depth is really the limit for these jack sockets, and it’s borderline for rotary pots.

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rainbow wiring

Roland 702A VCF wiring fun

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