G UITAR TRACKS
DAVID KLAUSNER
MIDI Guitar
their sonic palette, and they have always
been a little envious of the broad range of
sounds that keyboard players can conjure
up with the touch of a button. But envy no
more, because by using a MIDI-compatible
guitar as a controller, we can access the same
synthesizers, samplers, and other gear that
keyboard players use. While there are some
limitations using the guitar as a MIDI controller, it does allow access to all those great
sounds. With the right gear and a little effort,
guitarists can play any of the broad range of
sounds available to keyboard players.
MIDI Guitar Basics
If you’re not familiar with MIDI, it stands for
Musical Instrument Digital Interface, and is a
digital protocol that is used to transmit performance and control data, in this case allowing you to play the guitar, but trigger sounds
from a sound module, keyboard, or software
instrument. There have been several different
systems over the years for getting MIDI signals
from a guitar, but the major hurdle in using an
actual guitar (as opposed to a guitar-shaped
Z-Tar) is that you need some sort of pitch-to-MIDI converter. Roland Corporation’s hex
pickup system is the longest lasting and most
popular type of interface.
strings’ signals and converts them to pitch
and velocity (volume) information. There have
been internal converters using hex pickups,
such as the now defunct MIDI Axe system,
but most systems have used external boxes
that are connected to the output of the hex
pickup via a special 13-pin cable. Hex pickups
can be either magnetic designs or under-the-saddle piezo elements. They are available as
optional add-ons for your guitar from compa-
Tech, and guitars factory-outfitted with hex
pickups can be had from the likes of Fender,
-
panies currently making pitch-to-MIDI converter boxes include Roland and Axon, and
they both offer units that are just converter
boxes, as well as units with built-in sounds.
The system consists of a special hex pickup,
where each string has its own output, and
a converter box that takes those individual
Getting Started
equipped guitar and your pitch-to-MIDI
converter, plus a sound module if your converter doesn’t include one. You’ve still got
to do a little setup work before you’re ready
to play. Each string has its own output, and
you have to set the sensitivity of the converter to match your playing style. Too much
sensitivity and you’ll get false triggering and
doubled or ghost notes. Too little sensitivity, and you may not trigger the note when
you want to. Most systems will let you save
presets, so that you can have one setup for
fingerstyle, for example, and another for
when you play with a pick.
You also have to define pitch bend ranges.
and using a wheel or lever to alter pitch.
With a guitar, it’s obviously a little different,
and you have to tell the converter box when
to bend a note, and when to create a new
“note on” message. Too wide a range can
make hammer-ons sound like bends, and too
narrow a range will trigger a new note when
you bend. In addition, some systems will
operate in strict mono and poly modes, so
that you can either play chords (poly mode),
or bend notes (mono mode), but not both. I
generally prefer to have a blended system,
but strict poly mode can be useful when playing sounds like a piano, where any bends will
sound really unnatural, and the strict mono
mode lets you bend notes for a solo, but
keeps false triggering down since the converter sees only one string at a time. I also
use fixed poly mode when playing percussion
parts, since if I set a small interval for a new
note on message, I can do rolls simply by
using a very wide and fast vibrato.
Getting There On Time
The last subject we’ll tackle today is latency.
There is a small gap of time between when
you hit the note on the guitar, and when
the synth actually generates the sound. In
the early days of guitar synths, this time
gap, or latency, was pretty big—often up
to a quarter second—and required quite an
adjustment to your playing style to stay on
the beat. Modern systems are much faster,
but you should be aware that the lower the
pitch, the longer the latency, so the guitar
will track better in the upper register. I’ve
yet to play a system that doesn’t require
some kind of compensation in order to play
in time and to cleanly play each note with
the proper attack and without false triggering, but if you can make those small adjustments, MIDI guitar can open up a whole
new world of possibilities.
This photo shows a guitar with a 13-pin output, and two of the converter boxes that accept a 13-pin signal and convert it to
MIDI, the Roland GI20 and the Axon AX100. The Yamaha VL70M is a popular monophonic sound module for guitar synth.
David Klausner
David Klausner has been playing guitar and bass
professionally for over 25 years. He has owned his
own commercial studio, and worked at major studios in
New York and Philadelphia. He is a Sales Manager at
Sweetwater, and can be reached at david_klausner@
sweetwater.com or at (800) 222-4700 ext. 1314.
