Why do I not get stereo output of my drums through the mixer?

Question

I am trying to mix my electronic drum kit with music from my iPhone so I can play along with tracks on my drum kit.

Here is my drum kit controller with outputs.

And here is my mixer:

I am connecting things as follows:

drums iphone
  |     |
  -------
     |
   mixer
     |
 headphones

The drums I connect via the 'phones' output (as I presumed this would be stereo) and I use this cable:

I connect my iPhone with a similar cable.

I connect to my headphones with this adaptor:

However, when I listen the sound in the headphones is only in one ear!

I suspect the problem is something to do with these cables I am using, but I wanted to be sure before I purchased any more gear.

Thanks in advance for the help!

Answer 1

The problem is that the mixer is fully monaural (mono) and your headphones are stereo. Your mixer’s output is not designed to work with headphones. A TRS cable connecting the drum module to the mixer will not help because the mixer will only see mono.

The quickest, easiest way to play along to music on your iPhone is to plug the iPhone into the drum module's AUX IN jack (using whatever adapter you're currently using to plug it into the mixer) and plug your headphones into the drum module's PHONES jack. Then you'll hear everything in both ears and in stereo. This use case is what the AUX IN jack is for. You don't need the mixer at all.

In comments, you asked if you’d be better off using the MIDI OUT. The answer is no. MIDI is a digital interface that carries performance and configuration data, not audio. (It allows electronic instruments and computers to control one another.)

If you were dead set on using the mixer, you'd need to buy a headphone amplifier that accepts mono input and is capable of sending the mono signal to both ears. And, even then, you'd only hear one side of the iPhone's stereo. On some familiar recordings, you'd definitely hear things missing.

There are a few other points to make that don’t apply to what you’re trying to accomplish, but may help you understand your gear more fully.

• To connect your drum module to a mono system, you would ideally use the L/MONO output, not the PHONES output, which is designed for headphones.

• An additional problem with using the PHONES output to feed a mono system is that the individual pieces of your kit will have uneven volume. In the stereo field that you hear from the drum module’s PHONES output (when you plug headphones into it), you’ll hear hi-hats more strongly on one side and ride on the other. Same with the toms. If you connect this stereo output to a mono input, you’ll only hear one side of the stereo field, causing one side of the kit to sound weaker than the other.

• To connect your drum module to a stereo system, you would want to use both the R and L/MONO outputs, not the PHONES output.

Answer 2

That cable you use to connect the drums to the headphone out is not stereo. You need a TRS cable (Tip Ring Sleeve). It will look like your other cable which has one more line around it on the sleeve.

The first pic shows a TRS (Stereo) 1/4" plug.

The next one shows a TS (mono) 1/4" plug.

Also the headphone Jack on the mixer might not be the best level coming into your mixer. Ideally you want to use both jacks in the output section into two channels. Or into one stereo channel.