Mixers And Interfaces

Mixer boxes can be very useful in connecting multiple KeyMusician Keyboards to the same amplifier. I use them both in my home studio for practicing with more than one musician, and also in recording multi-player pieces.

Also, in performing, I have found the use of a mixer box, together with a MIDI interface, to give the two of us tremendous flexibility, where we can at-will play each others' synthesizers, with one or more different synthesizers on each laptop. This lets us use combinations of our favorite synthesizers on Windows, Mac, and Linux.

Before I dive into explaining the use of mixer-boxes and MIDI interfaces, I will first show you various audio cables (purchased at places like Guitar Center, or RadioShack), which are useful in connecting your laptop to mixer-boxes and amplifiers:


Audio cables and plugs (left to right, A to H)

A. Microphone, with 1/8” (3 mm) mono plug (male) – microphones can also have 1/4” (male) plugs, or XLR plugs

B. 1/8” (3 mm) stereo (male) plug, to dual XLR connectors, for connecting to house/hall/church sound system

C. 1/8” (3 mm) stereo (male) plug, to 1/8” (3 mm) stereo (female) plug-in

D. 1/8” (3 mm) stereo (male) plug, to dual RCA plugs (male), for connecting to a home stereo system

E. 1/8” (3 mm) stereo (male) plug to 1/8” (3 mm) stereo (male) plug, the most commonly used cable

F. Dual 1/8” (3 mm) stereo (male) plugs to single 1/8” (3 mm) stereo (female) plug Y-cable

G. 1/8” (3 mm) stereo (female) plug-in, to 1/4” mono adapter plug, used for plugging into a guitar amplifier (silver color)

H. 1/8” (3 mm) stereo (female) plug-in, to 1/4” stereo adapter plug (gold color)

I reference these cables or adapters later in the article by the letters in the list above.

And here is another adapter cable, and a USB MIDI interface:


(Audio Cable “I”, and MIDI Interface “J”)

I. 1/8” (3 mm) stereo (male) to dual 1/4” mono (male) adapter cable

J. USB to dual MIDI plugs MIDI Interface

I reference these cables or adapters later in the article by the letters in the list above.

Mixer-boxes Used In Performing

When we started out performing, we used a simple “Y” cable (item “F” in the first picture above) to connect the audio plugs of our two laptops to our amplifier.

To do this, one of the Y-cable's 1/8” (3 MM) male plugs was plugged directly into the first laptop, and cable “C” was used to connect the other laptop to the other 1/8” male stereo plug of the Y-cable. We used cable “E” to connect the female plug of the Y-cable to our amplifier's “AUX IN” plug (on the right), or to its “INPUT” plug (on the left - using adapter plug “G”), of the amplifier's panel shown below:


The Plug-In & Control Panel Of Our Amplifier

We used this arrangement for performing with “The Big Easy” country-western band for more than a year, and it was sufficient for what we were doing there.

Unlike the other performers who did the vocals (and thus needed microphones), we positioned our amplifier behind us so that we could hear the music we were improvising. Where we used no microphones, the amplifier being behind us would not cause a feed-back loop screech.

To avoid such a feed-back loop screech, the other performers positioned their amplifiers in front of them (and in front of their microphones).

If it had been necessary to position our amplifier in front of us, we would have needed either earphones from our amp, or a stage-monitor speaker.

Now that we are performing on our own, as a band called “The KeyMusicians”, we need more flexibility and variety.

We use different synthesizers on our two laptops, and are able to play any of those synthesizers depending on the KMK configuration files we select.

To allow us this flexibility, we make use of the following mixer box:


Alesis iO2 Mixer Box and Audio & MIDI Interface

This mixer is also a high-quality audio interface, connected via a USB cable, and it has a MIDI interface. Another nice thing about this mixer-box is that it is powered by the USB cable, and thus doesn't need a separate power-supply.

There are XLR plug-ins for two microphones, but to use them, the amplifier would have to be positioned in front of our microphones (and we would need a stage-monitor speaker or earphones). Also, the gain level would have to be adjusted differently for using a microphone as opposed to the line-level input from the laptop. We've found it easier to use the house sound-system microphone instead for announcing the musical numbers.

One of our laptops is connected to this interface via a USB cable, and the other laptop's audio output plug is connected to the mixer box using adapter cable “I”, connecting to the left and right “Line Input” plugs-ins.

The interface is connected to our amplifier using the “PHONES” plug (at the lower left of the picture above). To do this, we use adapter plug “H”, and audio cable “E”.

To allow us to play each others' synthesizers, we use the MIDI interface included in the mixer-box (accessed via USB on the first laptop), and another USB MIDI interface (“J”, in the second picture of interface cables), connected to the mixer-box and the other laptop via its USB cable.

The “MIDI-In” (white) plug of the second laptop's MIDI interface is connected to the “MIDI-Out” plug of the mixer-box, and the “MIDI-Out” plug of the other laptop's MIDI interface is connected to the “MIDI-In” plug of the mixer-box.

The KMK configuration file uses different entries in the “MIDI Output To” drop-box, to select the different synthesizers, as shown in the screen-shot below:


The Help/Setup Pane, Showing Selection Of The M-Track MIDI interface (similar to the Alesis iO2)

Here is a picture of two computers connected together (a desktop, not shown), and a laptop. We use this combination for practicing playing music together. In this case, an M-Audio M-Track mixer-box is used, which is similar to the Alesis iO2:


Components Connected Together For Music Practice, With An M-Audio M-Track Mixer-Box

The mini MIDI keyboard in the picture is occasionally used for testing, but could be used for playing if a need existed.

In this setup, the “Phones” plug is used for the sound-system (amplifier), and the output plugs of the mixer-box go to the audio input plug of the laptop (for recording).

Here is a picture (enlarged from the above) of the M-Audio M-Track mixer-box. As you can see, it is functionally the same as the newer Alesis iO2:


M-Audio M-Track Audio And MIDI Interface Mixer-Box

You can watch a video of us performing together using this setup below:

Mixer-box Used In Our Home Studio

Here is a picture of the mixer-box we use in our home studio:


Alto ZMX52 Mixer-Box Used In Our Home Studio

Unlike the mixer-boxes described earlier, this one is not USB powered. It has a separate power-supply plugged into the top of it.

This mixer-box has a single microphone (or mono line-level input) channel, with a separate gain (amplification) control. It also has two additional stereo (left/right) channels, each with both a balance and level control. In addition to those, it has a stereo AUX IN channel, which can be sent either to the mix (which is what we need) or to the headphones.

If needed, the stereo channels could connect to their left and right sides separately (as a monophonic connection), which would let you connect four different computers (six if you used the AUX IN channels). These are in addition to single microphone (or line in) channel. So this can allow you to connect as many as seven audio sources.

Since we use our home studio for recording, we use the stereo channels (2/3, 4/5, and AUX IN) for stereo input.

So we connect the output of the Alesis iO2 mixer-box (already connecting two computers - stereo) to channels 2/3, the recording computer (stereo) to channels 4/5, and a Yamaha S90-ES synthesizer (stereo) to the AUX IN. An additional computer (having a MIDI keyboard) is connected (mono) to channel 1, using cable “E” and adapter plug (mono) “G”.

The headphones jack (stereo) is connected to the home stereo AUX IN connectors, using using adapter plug “H”, and audio cable “D”.

When we record, we connect the “Main Mix L/R” plug-ins to the recording computer's line level audio input plug (blue), using cable “I” (from the list of interface cables at the beginning of the article), as shown in the picture below, plugging into the blue plug-in:


Audio Plug-Ins Of Desktop Computer – The Blue Plug-In For Line-Level Aux Input

If you don't have the line-level aux input plug on your computer (as would be the case with a laptop), you plug it into the microphone plug (the pink plug-in in the picture above).

The end result of all of this, is that we can connect a lot of different musical instruments together, all playing at once, as a single stereo input to a quality amplifier (our home stereo system in this case), and also to the audio input of a computer doing a recording of the music of all those musical instruments playing together, without the need of any microphones. Directly-connected audio yields better audio quality than microphones.

I hope this article gives you a lot of new possibilities and flexibility in performing, and also in recording your music!

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