Using a Guitar with MIDI to Drive a Synthesizer

Voodoo Shilton and I talk about musical geek stuff every so often because, much as everyone hates hardware, it can do some amazing things.  One of the reasons I love my Godin xtSA guitar is that it has a built-in synth access and the action is quite fast ... but it's not the only way to do it.

Before getting supremely geeky with this, here are the basics:  a normal guitar output is a 1/4-inch plug and it carries an analog waveform of the total guitar sound.  It was good enough for Charlie Christian, it was good enough for Hendrix.  The extension on this comes via MIDI which goes from a 13-pin port on the guitar to a port on a guitar synthesizer such as a Roland GR-20.  There are multiple guitar synthesizers available but all, to my knowledge, use a 13-pin cable to connect.  NOTE:  This is not a standard MIDI cable and is significantly expensive at about $80 US for a twenty-foot cable.

The conversation with Voodoo part was about another way to do it.  Rather than having a MIDI 'interpreter' on the guitar that sends MIDI code out on an expensive cable, how about using the standard 1/4-inch cable and making MIDI from that.  A device that can do this is a SONUUS I2M and here's a video demo:

This gives a taste of MIDI from the guitar as you can hear sounds a guitar just doesn't make.  However, getting into what's beyond it is the supremely geeky part.


The SONUUS I2M has some huge advantages:

• You don't have to replace your guitar with one that's got MIDI built-in
• It's a very inexpensive device
• No expensive cables
• Convenient software to make it easier to use
• No need to get a dedicated guitar synthesizer as you can use an inexpensive MIDI sound module to do the same thing for less  (a MIDI sound module is a synthesizer without a keyboard)

These are all very cool things but it's more complicated and saving a few dollars might not be your best move.

The more expensive solution goes two ways as you can get one of quite a few models of Godin guitars with built-in synth access.  With this solution, MIDI interpreting is fully-integrated into the design of the guitar.  A somewhat less-expensive solution is to get a MIDI 'pickup' that can be attached to an existing guitar near the bridge.  It's not a very elegant solution but it works and you get to keep your Stratocaster.


So what comes is that you need to decide on whether it's better to do the MIDI interpretation on the guitar or on the SONUUS gadget that's plugged into a USB port on your computer.  One of the most crucial points is the way the MIDI signal is created.  When it's on the guitar, a MIDI command will be generated for the activity on each string.  However, when it's done in the SONUUS gadget, the MIDI commands will be created based on a single waveform.  It's more complex than that but it's generally true and this means there will be more 'granularity' and consequently higher resolution and accuracy in the signal from the guitar.

Another key aspect to this is whether the 1/4-inch signal is lost at the point of the MIDI converter.  If that's true then you would have the sound of the synthesizer but you wouldn't have the native sound of the guitar.  That won't satisfy you for long as you will want to mix the sound of both, even if it's only to experiment to hear what it sounds like.  (There are multiple SONUUS units and likely at least one of them has a THRU that lets you send the 1/4-inch signal on to amplifiers, etc.)

Guitars with built-in MIDI have multiple ports so it's no problem to play normal guitar and MIDI at the same time.  The effect can be stunning as you might use a bright, clean sound on the guitar and just strum a guitar on one and then leave it to hold for the rest of the bar.  You'll get that bright, clean sound right away as it will have a nice attack and will present quickly.  If behind that you have a synthesizer voice doing a fat sweep, that will fill in as the bright, clear sound decays.  There's a glorious richness that comes from it so I'm quite sure you will not be satisfied unless you can play the native guitar sound and the MIDI sounds together.

Some of this stuff may be so esoteric and nitpicky that many people would never even hear the difference ... but some would.