1) Guitar -- I have a 2-button (channel, reverb) footswitch for my amp that requires a stereo cable, and the input jack on the amp that runs it is stereo as well. My question: instead of buying a stereo cable, could I just use a mono cable with a mono->stereo adapter on *both* ends? Signal quality, etc. doesn’t seem to matter here since it’s only a footswitch.
2) Keyboard -- Setup is: Keyboard->MIDI->Laptop->Amp/speakers. The input jack on the amp is 1/4" mono. The input jack on my laptop is, of course, 1/8” stereo. What kind of adapter should I use to connect my 1/4 mono instrument cable (one end plugged in the amp) to my laptop? A [Stereo 1/8” male]-to-[Mono 1/4" female] adapter? Or should both be mono?
Thanks for entertaining what are probably simple questions, albeit ones I couldn’t find specific answers to searching. Working on catching up to you guys.
1) No that won't work. One of the switches would work normally (whichever is hooked up to the tip) but the other would act as though it was constantly engaged.
2) Use mono at both ends. A stereo plug in the computer that combines both sides to mono at the amp end may work, but if the keyboard uses polarity inversion to enhance the stereo image, you will get cancellations in the output when they are combined to mono.
Take two 1/4" plugs, one TS and one TRS, and lay them side by side. Now think about the jack that the TRS will plug into-it will have three contacts that match up to the tip, ring and sleeve. Now look at the TS. You'll see that the sleeve is longer, so that it covers the same area as the ring and sleeve combined on the TRS. So on your TRS jack, both the ring and sleeve contacts will be in contact with the sleeve of the TS plug. Just as a side note, if you don't plug the TS all the way in (at both ends), you can get the tip of the TS to contact the sleeve. Then, the switch that was always engaged when the TS is all the way in will work normally, but the other one will be always off. This last bit of course isn't a practical suggestion, just something to help you understand why the TS cord won't work.