A little knowledge is a dangerous thing… Especially in my case!
I keep reading about people using TRS (stereo) jacks with their CP-251 and other MFs, rather than TS (mono). I’ve searched this forum and other places, but haven’t found an explanation.
Is there a reason why some people use TRS rather than TS?
Something to do with +5V ranging to -5V?
Where should I use TRS rather than TS? The red coloured sockets?
What differences will I notice?
Also, where can I find some example patches for LP + CP + MF-102?
First, let me try to answer your question about TRS cables with the limited knowledge that I have. The first part of the answer is simple and it has to do with the number of wires going through the cable. Cables usually either have two or three wires that are wrapped together and then soldered to some type of connector.
TRS means “tip”,“ring”,“sleeve” which correspond to the three segmented part of the connector. You can easily identify a TRS from a TS cable by the number of segments separated by a non conductor you will see as a ring going the connector. TRS has two and TS one. Two are conductors and one is groud.
TRS cables are also balanced and TS is not. In general, the term balanced has to do with sending out mirror images of a single, one with negative polarity and the other with positive which is used to reduced noise with longer cables. Another type olf connector that you will see on balanced cable is an XLR connector you will see on mics.
Now here is the part that I am a bit unsure on and I will leave some of the more technically estute people here to answer it but here is a first shot. Foogers use voltages from -5 to +5 for CV so yes, I suspect the reason is do to the use of jacks for CV. Also, cables going to expression pedals are TRS and are connected to all three contacts on the potentiometer inside the expression pedals.
See the information here on potentiometers and “voltage dividers” which is what they are doing:
The red colored sockets on the CP 251 are those that can be used with an expression pedal or other resistance source (which is what I like to use them for).
In most cases everyone is talking about using TRS cables vs TS cables for connecting CV signals, and not audio signals.
The reason, which is in every manual, is because of the way that the CV jacks are all wired. The ground is connected between each jack. When you plug an expression pedal into the CV you do require all three wires to communicate the pot position via a TRS cable. When you use a TS cable on any other CV specific to the unit you work with, you end up shorting one of the signals to ground, thus making your expression pedal in-expressive.
So, if you use an expression pedal anywhere in your MOOG rig it’s a good idea to use TRS cables. If you don’t use expression pedals, TS for CV are fine.
I’d just like to add something, in case it gets brought up…again. When putting a voltage to a jack, up to 5VDC, a TS cable is fine to use. The internal voltage on a 'Fooger will be grounded out, and will not interfere with the incoming voltage, so no need to worry about frying gear as long as the incoming voltage is 5VDC or less.
The wording in the manuals can be a touch confusing on this subject, so I thought I’d mention it.
Also, as far as CP and 102 patches, search on YouTube for examples. My videos include the 103, but my very first video series, part two in particular, explains a very basic setup.
When putting a voltage to a jack, up to 5VDC, a TS cable is fine to use. The internal voltage on a 'Fooger will be grounded out, and will not interfere with the incoming voltage, so no need to worry about frying gear as long as the incoming voltage is 5VDC or less.