Can I Wire two cables together to get two inputs into one output

Question

My question is simple: If I open up a guitar cable, or use the jacks from a guitar/pedal (I have a few lying around) and connect the hot outputs and grounds together, could I connect that to another cable, therefore get a 2 inputs connected to one output? I have a loop pedal that does this, but I want 3 inputs to one output in total.

My idea is this:

=======cable 1 hot====(to hot output) == == == cable 2 hot == == ==
-------cable 1 gnd----(to gnd output) -- -- -- cable 2 gnd -- -- --

(sorry for bad diagram; markdown is mean >:0 )

Answer 1

Edit: there seems to be some confusion here.

Based on the description in the question, I'm assuming you have two devices that output a line-level signal, and you want to connect those to a device that only has one input available.

If this is the case: don't wire the cables together directly. This may damage your devices: the output voltage from one device ends up in the output stage of the other device, which isn't designed to handle that.

There are several ways to do this safely:

1. use a switch, to connect one output at a time to the input. Simple, but requires you to turn down the output volume because a simple switch isn't guaranteed to make the switch silently.
2. use a mixer.
3. use a passive summing mixer. In its simplest form, this is just two resistors wired into the cable. This will result in a 6 dB signal loss.

  INPUT 1 -------\/\/\/\---+
            ---+   R1  10K   +------------ OUTPUT
               |             |       +----
    INPUT 2 -------\/\/\/\---+       |
            ---+   R2  10K           |
               |           (shields) |
               +---------------------+

The other way round: splitting the output of one device to feed 2 devices, is described in danmcb's answer.

Answer 2

It absolutely depends on the type of output.

What you want to do is called "distributing" the output to a number of inputs. Some types of output are actually designed to be distributed, some are not. Some can, but only with a bit of care and technical consideration.

(To know how and how many you need to know a bit of electronics, there is something called "impedance matching". I am going to try to not get into that.)

Some examples:

1. A "line level output" from a mixer (like the MIX outputs or an insert send point) can be distributed to a reasonable number of outputs in parallel (i.e. hot to hot, gnd to gnd ...) - how many is "reasonable" depends on impedances but 3 or 4 should be no problem.

2. A microphone or guitar output generally cannot be distributed - they are not designed to be. You should first amplify the signal through an appropriate pre-amp which has a line level output, and distribute that instead.

3. The speaker out from an amplifier is not line level - it is "hotter" (i.e. more volts and also ability to supply current). You can connect an amp to more than one speaker - but with care. Consideration must be given to the impedances of the speaker, the rating of the amp, and parallel/series configuration.

4. A headphone output can sometimes drive more than one pair of headphones - but again with some care about impedances, and the results may be unsatisfactory as the headphones may differ a lot in volume, and there would usually be no means of adjusting them individually.

So - the answer to your question is - "it depends". Your case sounds like case 2, so what you propose is not recommended.

Answer 3

You can use a passive "AB Y" pedal to accomplish this. It's probably more common to want to split one source to two destinations, but you can also operate them in the opposite way.

Overall though, a (small) mixer is probably a better solution in that it will give you the ability to control the sources independently.