Redmere Soloist Footswitch Mystery

[Sowhat]

Does anyone know what these are?



I can see 180 ohms and 70J which I imagine is the datecode but I can find nothing on that part number. These are at the end of an 8 meter long 8 conductor shielded cable coming from the Redmere Soloist amplifier head to a hand cobbled prototype programmable footswitch. There are 7 signal lines so there are 7 of these supported by a PNP transistor and a resistor each. I'm trying to back engineer a schematic for this footswitch but these gadgets make that a bit hard.

By signal lines I mean unclocked digital signal level lines like TTL.

[tedmich]

how many leads to them? I'm thinking some kind of ancient optoisolator/SS relay

8m cable? The Redmere wasn't THAT loud!

Footswitch isn't from Redmere eh? They were plenty complex without it, maybe it never did (or will) work?

[Sowhat]

The footswitch is made by Redmere, it's just that it was constructed with prototype mechanics... perf board, hardwire traces, tack soldering. It must be some prototype rushed out of the factory for a trade show maybe.

Yeah the cable is pretty long as you can see from these shots I took after rebuilding the footswitch and salvaging the cable. The only deal I can get around here is something like $1.58 per foot, the only catch is that I would need to buy a 1000 foot spool... glad the existing cable cleaned up nice and is in good shape.



I don't want to lift the devices and seeing that they are on breadboard the leads go every which way but as far as I can see it's got 3 pins on each end, but then again I'm not completely sure... it's hard to get a good view.

I was thinking about maybe some sort of digital line filter because these are digital signals controlling their capacitive touch switches FET's and NOR gate latches. Inside the Redmere amp itself these lines attach directly to the signal busses hooking all the preamp and effects pwb's together. Those are bare wire busses so it looks like they were not very concerned about shielding there. Maybe that long cable run overwhelmed the under protected and shielded digital circuits contained inside the amp head and the signals needed a boost or a filter or something.

One other little thing, the shield of the cable is not ground, it's -15VDC or VSS on the 4001 NOR gates. +15VDC or VDD is the red wire inside the shield. They are using the shield as the 9th wire.

[tedmich]

wow, good luck, it looks nothing like the Soloist footswitch at backfromthesixties.co.uk !


waiting for the digital age in an analog world...

[Sowhat]

I've been in correspondence with Christopher Devine of backfromthesixties.co.uk fame and we are having a little voyage of discovery over this. Now with these few puzzle pieces I can begin to see the evolution of this thing.

The one I have is the earliest incarnation of this footswitch, literally hot off the tech bench. As I surmise, some last minute idea or detail before the big Redmere unveiling back in the late 70's. This one has some drawbacks for sure the main one is that the dip switches can't be set unless you disassemble the footswitch. That kind of thing happens with prototypes and this brings us to the one on the backfromthesixties.co.uk site. This is a more polished version putting the switches accessible on the bottom of the footswitch. This worked I guess until they internalized this switch panel inside the amplifier head itself in what appears to be the last revisions of this amp.

Then again... maybe the switches were inside the head at first and then they externalized them to the footswitch for easier access but could not make the big unveiling with anything but a prototype (the one I got). Finally they made the footswitch with the switches on the bottom and the only known version to actually be user programmable. mmmm... this is all highly speculative.

I understand that the production run of these amps was extremely low maybe a dozen or two over it's entire life. It's interesting that this aspect of the amplifier system changed that much in such a short time, I don't think they ever got it exactly right or easy to use but they certainly tried.