One of the most recent additions to the field is the Axon AX100 pitch‑to‑MIDI guitar system from Blue Chip.
All fingers and thumbs in front of a keyboard? John Walden provides a few pointers to make sequencing using a MIDI guitar controller a less fretful experience.
There is no doubt that the vast majority of people turn to a keyboard to get musical ideas into their sequencer. The ease with which the physical action of a keyboard can be designed to generate note‑on, pitch, velocity and note‑off information has made it a reliable and versatile controller for the MIDI musician. That is, of course, unless you're a guitarist (or a drummer, saxophonist, violinist...), when that row of black and white keys sitting between you and your extremely sophisticated sequencer can seem more difficult to master than a circuit diagram for the Space Shuttle.
Enter the 'alternative' MIDI controllers which allow you to beat, blow or strum your way to a MIDI‑based masterpiece. Guitar‑based MIDI controllers have been around for a good number of years and various designs have appeared during this time. The most common form consists of a pickup that provides a means of converting the pitch of a plucked string into a particular voltage and, from this, generation of a MIDI note. The advantages of this approach are that it is relatively inexpensive and can be mounted onto a standard guitar (or bass — see page 218).
There are, however, a number of catches (or design flaws, depending upon your point of view!) with this type of system. The basic process of 'pitch‑to‑voltage' conversion is not as reliable as the 'note‑on, note‑off' mechanism of a keyboard. As well as the notes you do want, therefore, any unintended vibrations (commonly caused by fretting or pick‑hand movements) will also be translated into some sort of MIDI information. The result can often be somewhat less than musical, as the pickup struggles to convert every buzz and rattle into a specific note. In addition, because the pickup will, by design, take longer to convert the pitch of notes at the bottom of the guitar's range, there can often be a noticeable delay between hitting the string and hearing the generated MIDI note.
Both of these problems have resulted in many guitarists giving MIDI controllers a wide berth. However, with a little care and perseverance, it is possible for even a humble guitar player to exercise some control over his or her MIDI sound module. For those brave enough to try, this list of ideas and tips is intended to get you off to a good start.
1. If you are new to MIDI guitar controllers, perhaps the first thing to consider has nothing to do with the gear, but a lot to do with attitude. Asking a simple question can help at this point. Why do you want to use your guitar rather than a keyboard to generate MIDI data? If the answer is that (like me) you know far more about a fretboard than a keyboard, then ponder the following. Getting a good performance out of a MIDI guitar controller requires a considerable adaptation in playing technique, and many guitarists find this both limiting and frustrating. So which it is to be — spend some time adjusting what you do know to get the best you can out of your guitar, or start with Grade 1 piano lessons? Guitar controllers are not perfect, but with a little effort and a positive attitude, they can provide a viable alternative to a keyboard for communicating with your sequencer.
2. If you have the choice, do not fix your MIDI pickup onto your favourite Fender, Gibson or PRS, particularly if it has a low action to cope with the occasional manic solo. A low action will mean a certain amount of fret noise, and while this is fine for normal use, it can play havoc with the pitch‑to‑voltage conversion process of the MIDI pickup. If you can afford a second guitar for the MIDI pickup, then experiment with the action to achieve a suitable balance between playability and reliable tracking by the pickup. For example, the slightly higher action often used for slide playing might allow you to combine slide and MIDI use on one instrument.
3. Most MIDI pickups allow the sensitivity of each string to be adjusted individually. When installing a pickup, take your time getting an even response. This will help produce a smoother performance with any synth patch that is velocity‑sensitive.
4. If you can possibly forgo your 'extra slinky' light‑gauge strings, do use something a little heavier (an 11 or 12 gauge set should do the trick) as this can result in more reliable pitch‑to‑voltage conversion by the pickup.
5. To keep false MIDI triggers to a minimum, a really clean playing technique is needed. Unfortunately, this means that many of the techniques used in rock guitar to add expression (tapping, rapid hammer on/off, and digging in with a pick to produce various harmonic effects) are not suitable for use with a MIDI pickup, and will result in unwanted notes being produced by your synth. Keep your playing clean and simple.
...with a little care and perseverance, it is possible for even a humble guitar player to exercise some control over his or her MIDI sound module.
6. A common cause of false notes is re‑triggering of a note as the string is released. This can be kept to a minimum by not releasing the string entirely (mute the string with your fretting hand) when you end each note.
7. Experiment with different types of pick to see if you can reduce those unwanted 'glitches'. Using your fingers rather than a pick, or using a felt covered pick intended for bass guitar can help.
8. Consider the sound you are playing and don't overplay. For example, pad sounds are often very full with a wide frequency response, and only a few notes are needed to produce a big sound.
9. Trigger delays can become noticeable at lower pitches on the guitar neck and this can be disconcerting while playing, particularly with sounds that have a fast attack. Use the transpose function in your sequencer (or on the pickup if it has this facility) so you can play bass notes at a higher position on the fretboard.
10. Somewhat unpredictable velocity sensitivity can be caused by poor playing technique. If the pickup allows, reduce the dynamics while recording the part and then edit the velocity data within your sequencer (or copy dynamics from another part in the sequence) to put a little life back into the performance.
11. Take care to consider the chord voicings that you use and attempt to match the instrument your synth is trying to emulate. For guitar parts this will not be an issue, but if you are trying to create a piano part then consider how a pianist would put each chord together. Users of Emagic's Logic sequencer could put the Chord Memoriser function from the Environment to good use here.
12. If your synth allows, and where appropriate to the sound, edit the decay portion of the patch's envelope so that it has a short fade once the 'note off' message has been received (that is, when the string has stopped vibrating). This can result in a much smoother performance and compensate for an uneven decay across different strings.
13. Most MIDI pickups can be used in different modes. In 'poly' mode, MIDI data from all six strings is sent out on a single MIDI channel. In 'mono' mode, by contrast, data from each string is sent on a different MIDI channel. One use of this is that it allows the MIDI data from each string to be recorded on a separate sequencer track. This can make editing easier (and each channel can be combined once the part is in a finished form) and allows experimentation with pre‑delays on lower strings to bring them into time a little more tightly.
14. Even after you have done all you can to minimise false triggers by setting up the pickup and adapting your playing technique, a few unwanted notes may still appear. These notes are often of a very short duration and/or low velocity. Use your sequencer's editing functions to select short and low velocity notes, which can then be deleted (or, more safely, copied to a separate track). This can clean up a part considerably. Experiment with different values of note duration (eg. 64th notes) and velocities (eg. less than 10) until you find something appropriate.
15. If, following on from the above tip, you still have a few unwanted notes, then look for and edit 'double notes' in your sequence (where a note has been triggered twice at the same pitch in rapid succession).
16. Some false triggers caused by the occasional finger, pick or fret noise are often translated as unusually low or high pitches. If you know a part should only contain notes within a certain pitch range then delete notes outside this range. Some sequencers provide a 'pitch limiter' function that can be used while recording and will ignore notes outside a set range.
17. Solo instruments (including many wind instruments) should only generate one note at a time, and you should try to emulate this via MIDI to add a certain realism to the part. As a MIDI guitar controller can generate six notes at once, use of the 'voice limiter' function built into most modern sequencers will help here.
18. If your sequence is MIDI‑only, or you can mute any audio parts and still play along to the piece, then try slowing down the tempo of the track by a small amount (eg. 10 percent). This can make getting a clean performance on a difficult part a little easier. Extreme changes in tempo will not work so well with sounds that have a filter effect, as the speed at which the filter is operating will obviously influence how you play.
19. Take care with the quantise functions on your sequencer. While quantising can help overcome trigger delays on lower notes, if you are trying to emulate an instrument being strummed, it can also remove the slight delays between notes within a chord that create the impression of strumming. By contrast, keyboard sounds (like pianos) are generally not strummed(!) and quantising can help improve timing of chords.
20. If the part does not require pitch‑bend, then set up either your sequencer so that it filters pitch‑bend data out, or your pickup so that it doesn't transmit it. If you do need pitch‑bend then experiment with the pitch‑bend range of your MIDI sound so that you achieve the most effective control from your guitar. In most cases, the pitch‑bend range of the synth sound should match that of the pickup, but it is worth trying a few other settings to see what sort of effects can be produced.
Roland have a long history of making guitar synthesizers.