Hi all,
New to the forum. I’m primarily a guitar player. I own an mf-101, mf-102, and cp-251.
I’m looking for something that allows me to change what cv is being fed to an input on my fooger with a footswitch. So I would have an LFO and a Noise signal going into two separate inputs of a router with a switch that would allow me to choose which signal I output to the fooger.
Basically it would be a line selector but all the pedal ones out there just have TS in/outs.
T-Rex sells a stereo AB box that would work if you used “insert” cables (one end TRS, other end two TS one to tip and one to sleeve).
Otherwise DIY will be much cheaper.
Using what you have, the CP-251 has a mixer that can be controlled with an Expression pedal, and many other possibilities.
You don’t need TRS unless you’re switching an expression pedal. You can always use a “blind” T_S cable (ring not connected) to avoid the +5 V short on the 'fooger end, with a normal TS plug on the other. You might have to build it yourself though.
So -looking to avoid shorting so i can still control mf-102 frequency I could run a trs (or ts) from the cp-251 noise out to an input on the a/b, a trs (or ts) from the sample hold out to an input on the a/b and then a “blind” trs out of the ab into the carrier in?
Sorry for being obtuse. 
I’ll play with the mixer too.
No worries, welcome to the forum btw!
If you’re using the carrier in then there’s no need for any TRS cables, everything TS is fine. You should avoid plugging TS cables into the sockets marked as black on a white background, but only if you’re using expression pedals too.
Best of luck!
Really! Awesome. I thought any any ts would result in a short. Alright! I’ll just pick up a cheap line selector and start experimenting then.
I share your confusion. It is one of the obscure points when getting a CP-251 (which I just did). The official answer is in the ballpark of “TS is ok, TRS is a bit better, but not needed”. I don’t understand why they don’t just recommend TRS cables (and then in an appendix note what you can do with just TS cables). After all, people are purchasing a rather expensive item, so the slightly higher price in cables should not matter too much. But I am now stuck with a bunch of TS patch cables, which I might as well upgrade. There will come a time where I just don’t want to short.
But I am so stoked about the CP-251. I am going completely “Mad Scientist” now 
The only time you need a TRS connection is when using a passive device to attenuate the CV. Like an expression pedal or anything that’s just using a pot. The CP-251 generates its own CV, so you don’t really need TRS while interfacing it with your Moogerfoogers.
CP-251 manual, p 26 explains all!
https://www.moogmusic.com/sites/default/files/cp-251.pdf
Funnily enough, I think the +5V supplies on newer MFs are buffered in a way that using TS plugs has no short circuit consequences.
Thanks! I’ll play it safe and use TRS cables - after all, as a guitarist, I will have use for the expression pedals.