Hi Ron,
I have the Mini amp Gizmo & the Mk V cable which both work great with my G system but I want to also occasionally use my Carvin Amps with my Amp Gizmo instead of the Mk V.
These have a very simple single TRS switching interface where the ring toggles the 2 channels & the tip toggles the reverb on & off.

Clearly I don't really need the 4Qtrs cable so I wanted to make up a cable for this myself just using a single TRS jack & a butchered old midi cable as I would only need to use 2 pins on the amp gizmo plug?

Is this do-able?

Cheers
Ian

Sure, that's no problem. Connect the cable's shield to the sleeve of the TRS connector, and connect two of the wires from the cable to the tip and ring of the TRS connector. Which wires you use will determine which switch on the Gizmo controls the amp.

Excellent!

Prob use Pins 1 & 2 as that will then mean that my existing patches should work on my G system without changing anything.

Have a look at how the footswitch works. I assume that it's a two button footswitch, and you get the third channel when both switches are off. You want to connect the pins that correspond to the switches.

So if the footswitch selects channel 2 and 3 (channel 1 selected when both switches are off), connect the tip and ring of the connector to pins 2 and 3 respectively. If the footswitch selects channels 1 and 3 (channel 2 selected when both switches are off), connect the tip and ring to pins 1 and 3.

This will make buttons 1 through 3 select channels 1 through 3. This makes things consistent from amp to amp, and is normally how we build our cables.

The footswitch is a 2 button latching footswitch but one button connected to tip toggles the amp rev on & off.
The other button connected to the ring toggles between the amp clean & lead channels.

Ah, okay, my mistake - I had just talked to someone with a Matchless Independence which got me all confused!!

So I guess I will only need one switch to toggle the channel & a 2nd to toggle the Rev then?

Yes, that's correct.

For the info of any other Carvin owners with a TRS jack to switch channels & Reverb (X100B, Legacy, MTS, Nomad, Belair) I have now done this & it works a treat!

I wired the tip of a TRS plug plugged into the FS22 Jack on my Carvin amp to pin 8 on an 8 pin Din plug & the ring to pin 2 & sleeve to the Din plug shield.
I had to change switch 2 on the Amp Gizmo to Invert mode but it now switches fine & I can use the same patches on my G system as I use with my Mark V.

Switch 8 also needs to be in invert mode but it is already set this way for the Mark V so I did not need to change this.

Also Switch 1&2 must be grouped but I already have 1-3 grouped for my Mark V anyway.