Rotary Speaker Rewiring Question

[awgearhart]

I know this doesn't really have to do with stomp boxes (although there is a Footswitch involved to maybe it's relevant) but here we go.

I have a rotary speaker horn called the MTI Rotophaser (I'll provide a couple links below to give an idea). All of the researching I've done online does not show the exact model that I have. Some of the models have different footswitch configurations, connection types, etc.

My model has a hardwired connection from the speed selector switch on the Footswitch to the actual speaker cabinet while the bypass selector is hardwired to the Footswitch, but it has a quarter (¼) inch end that can be plugged/unplugged from the speaker cab itself.

I want to be able to "rewire" the Footswitch and speaker cab so that instead of being hardwired, I can plug and unplug both connections from the pedal and speaker cab. This gives me much more freedom with changing cable length and much more efficient storage options (so that a Footswitch isn't "permanently" connected to the cab). One thing that may be an issue is that apparently there is ~110-120 VDC being supplied directly from the cabinet to the Footswitch.

One of the links provided below has a hand drawn schematic although I'm not sure how accurate it is. I don't have my hands on my MTI Rotophaser at the moment so I can't post pictures of my specific one either (I will as soon as I get the chance).

Does anyone know of any type of multi-pin-like connectors I can use to wire the speed selector and bypass pigtails to? I would assume since the cab already has a quarter (¼) inch female connector for the bypass selection that the footswitch could get away with a quarter (¼) inch female connector as well rather than a multi-pin connector. I was looking into MIDI cables but I guess they can't carry high voltages across (since the MTI Rotophaser supposedly carries ~110-120 VDC directly to the Footswitch).

Any help would be greatly appreciated!

MTI Rotophaser: https://reverb.com/item/459969-mti-rotophaser-rotary-horn-vintage-1970-s-model-rm-80

Hand drawn schematics: https://noisemikers.com/mti-rotophaser-with-footswitch-schematics-and-images/

**Keep in mind both links do not represent my exact model since they both do not have hardwired cables from Footswitch to cabinet directly**

[PRR]

You are in the USA/Canada part of the world of electricity? (The available plugs differ.)

Yes, there seems to be 120V AC to switch and motor. So it is same as wiring wall lamps. The connector has to be heavy enough, not just to carry the load, but to blow the cellar fuse when things go short. So basically lamp-plugs. However few are more than two "live" pins. (Do NOT re-assign a ground-pin as current carrying.) Also you may not have live voltage on an exposed (male) pin.

I am VERY surprised there is no safety ground to the metal switch box!! Fashion in safety has changed but I doubt this was ever fully legal. (I wonder if the connector was.)



Today I have used the big NEMA many-pin plugs for trivial 120/240V metering. They are not cheap. (They seem to be cheaper than when I bought some.) Beware of panel/cord and gender variations. The male panel mount is popular for generator inlets but LETHAL coming out of a source (the speaker/motor unit).
https://www.amazon.com/NEMA-L15-20-Plug-Receptacle-Set/dp/B01AMTW8WQ

BUT these plugs are sometimes found on/near stages wired for VERY different purposes. If you are cleverly unlucky you could switch-short somebody else's 20A 240V circuit and burst a switch.

[PRR]

https://www.amazon.com/dp/B06ZZ6HXQM/ref=sspa_dk_detail_5

This is rated 30A AC 500V and is far more waterproof than your organ. Not likely to find a "same" connector at a gig (unless playing the airport). Cable-end may be awkward for you; there may be a chassis-mount of the same type. Or it may be possible to mount the sockets-carrier in a precision chassis hole, held with its "cable body" screwed on the back.

Another: https://www.amazon.com/Waterproof-Connector-Connect-Aviation-Industrial/dp/B07B7H6L7Q?th=1

[awgearhart]

Thank you for providing these, they are very useful.

When it comes to cables, how do I ensure I have the right cables for these? Or will I need to create custom cables for each switch?

[pinkjimiphoton]

i had one of these, it used a modular plug for the footswitching. i will see if the guy that ended up with it can get me some pics for ya. the plug was rectangular with a bunch of pins,  and let you engage/bypass the effect and change the speed.

[anotherjim]

For my (ex organ) 2-speed Cheesewheel Leslie I included a 5v PSU and got a dual SPDT relay maker module. The relays were 250v contact rated and wired to duplicate the original organ console switching. I copied the original RC "snubber" networks across the switch contacts. There were only 2 networks each from the common live input to the start/stop relay across to each motor coil live-side feed after the slow/fast relay contacts. A panel switch (2 pole rotary limited to 3 positions) was fitted to control the relays wired via a switched TRS jack so that a standard dual latching footswitch can be plugged in that overrides (disconnects) the panel switch.
The Leslie already had a safety ground wire fitted to the motor frame to go direct to the IEC cable inlet. The relay module I used has optoisolated relay coil drivers so with a transformer 5v supply (or other isolated types) there are x2 levels of isolation from the AC mains input to the control inputs.
I did include the original round Leslie multipin motor connector, but that's internal and left connected.

[pinkjimiphoton]

these are the exact connectors that were on my mti rotophaser.
i contacted the guy who "borrowed" it 20 years ago claiming it was stolen and said i don't want it back, but need to see it so i can get some pics. still waiting.

anyways..

https://www.ebay.com/itm/CINCH-JONES-S321-P321-21-CONDUCTOR-CONNECTOR-PAIR-NOS-MULTI-PIN-MALE-FEMALE/192885688075?hash=item2ce8e2070b:g:LyYAAOSwOA1Z86hS