Yamaha G50

The so‑called guitarist's dream has failed to deliver on so many occasions that many guitar players now seem sceptical about the whole concept of MIDI guitars. Does the Yamaha G50 give us cause to rethink our prejudices, or does it simply reinforce them? Paul White finds out.

Seductive though the concept of playing MIDI sounds from a guitar is, past attempts have been plagued by delay problems, tracking problems, or a combination of the two. Furthermore, guitarists are used to having very precise control over their sound via their playing technique, yet traditional MIDI sound sources tend to be relatively inexpressive unless you patch in a lot of real‑time controllers. In the light of these historic problems, is it worth pursuing the MIDI guitar dream further, or should we simply conclude that the guitar was never meant to be anything more than a guitar? Yamaha obviously feel they have something new to bring to the party, so perhaps it's best to reserve judgement until after putting their new product, the G50, to the test.

G50 Design

Housed in an innocuous black, 1U‑high rackmounting case, the Yamaha G50 is simply an interface between a guitar fitted with a G1D split pickup system and an external MIDI sound module — there's no on‑board synth here, as there is with Roland's GR1 or GR09. If the split pickup looks familiar, that's because it was designed specifically to be interchangeable with Roland's GK2 pickup unit; presumably the idea is that existing Roland users will find be more tempted to change horses if they don't have to invest in a new pickup. It is possible to use the Yamaha G50 without a split pickup, but in this mode the conversion is purely monophonic and the success (or otherwise) of the process depends to a large extent on how cleanly you can play.

Looked at simply, the G50 receives information from each of the six sections of the split pickup, analyses the pitch, then translates this to MIDI note, velocity and pitch‑bend information. However, analysing the pitch of a guitar string is difficult because of the rich harmonic structure of a plucked guitar note. Furthermore, until the noise of the pick against the string has passed, there is no pitch to track, and even when the note has steadied, the process of extracting the pitch takes a finite amount of time. The usual outcome of this process is inaccurate pitch recognition and a noticeable delay, especially on the lower strings.

Current systems attempt to address these problems by using fast digital analysis algorithms to make a quick guess at the pitch, then as the note stabilises, constantly updating the pitch data. If this is done fast enough, the tracking gives the illusion of being both instantaneous and accurate. Though no specific details on how the Yamaha system works have been released, it has been mentioned that advanced neural net technology (computers that learn) was used at the design stage to help the system differentiate between intentional notes and misinterpreted harmonics or noise.

The G50 provides memory locations for 128 user programs, though as the unit contains no sounds, you might be forgiven for wondering why it needs any at all. The idea is that you can set up different picking sensitivities for different songs, make use of split functions, which place different sounds on different strings, or save custom settings for the new picking position feature, which allows the sound to change depending on how close to the bridge you pick. A program can also contain a MIDI patch change, so that the appropriate sound is called up automatically.

User Interface

Though its primary use will probably be with a 6‑string guitar, the G50 will also work with a 4‑string bass, providing that the bass is fitted with a suitable divided pickup. A switch on the rear panel selects guitar or bass operation. Sharing the rear panel are the MIDI In and Out sockets, a Sustain/Hold pedal socket, a direct output for the regular guitar pickup, and an input for the obligatory (and exceedingly irritating), external power supply. I don't mind separate power supplies too much on dedicated studio gear, but I would hope that Yamaha have enough confidence in the G50 to expect some people to use it live — and flimsy push‑in power connectors are in no way compatible with my experience of the live performance environment!

Aside from the G1D pickup input, and the jack for a regular guitar input, the front panel has only eight buttons, an LED display, and a power switch. There's also a printed parameter crib sheet on the front and top panels, which saves having to constantly refer to the manual. Editing is via the usual menu system, with parameter select and value buttons doing most of the work.

Operationally, the G50 has three distinct MIDI modes:

• Multi‑Channel Mode: in this mode, any six consecutive MIDI channels (excluding channel 10, which is reserved for drums), can be selected, and each guitar string transmits data on its own MIDI channel to an external multitimbral synth set to polyphonic mode. All the strings can thus play different sounds, if required, and because the mode is polyphonic, fretting a new note on a string won't kill off the sustain of the previously‑sounded note on that string. However, because the strings are on different channels, independent pitch‑bending is possible. This mode may also be used with synths that support Mono mode (one voice per MIDI channel), though playing a new note on the same string will obviously cut off the note that was previously playing. The Oberheim Matrix 1000 is a good choice for using in this context, as it has a dedicated guitar mode, which places each of its six voices on consecutive MIDI channels.
• Single‑Channel Mode: in this mode, polyphonic operation is possible, but because MIDI pitch‑bend information affects all notes played on the same channel, the ability to bend individual guitar strings by different amounts is lost. Pitch‑bend data is derived from the last note played, and if the note is bent by more than a semitone, it will jump to the next semitone up. Though this sounds rather restricting, it's a viable way to work if you have a non‑multitimbral sound module that doesn't support Mono mode. It's also useful for monophonic tone generators such as the Yamaha VL series.
• Mono mode: this is selected automatically if the regular guitar input is used instead of the divided pickup. In this mode, all the data is transmitted on one MIDI channel and only one note can be played at a time. In addition to the regular user programs, the G50 contains three further preset programs specifically for use with generic General MIDI devices, Yamaha's own MU50, MU80, VL7m or VL1m (version 2).

Using The G50

Before using the G50 for the first time, the divided pickup must be fitted to the guitar, either using the sticky pads and shims provided or, more permanently, with a screw and spring arrangement which provides conventional pickup height adjustment. Once the pickup is in place, the string sensitivity needs to be adjusted so that all the strings are equally responsive — a special Input Level mode button is provided for this purpose. Activating the G50's inbuilt guitar tuner is also a one‑button operation, after which you need to pick the appropriate MIDI mode to suite your synth and, most importantly, ensure that the pitch‑bend range of the G50 is set to the same value as your synth. A range of 12 semitones is probably best for most guitar styles, in order to accommodate string bends and hammer‑ons. Unlike most other guitar synths I've used, the G50 has separate parameters for string level, note trigger‑on intensity and note trigger‑off intensity, the latter two being a part of the program information. This is a great help in preventing false triggering. There are also several different velocity curve options.

The various parameters are set via the display, where the four LED characters do their best to convey both letters and numeric data information. After setting the guitar sensitivity characteristics, there's a chromatic mode which can be set on or off, transpose, and numerous parameters relating to whatever tone module you're using. These latter include program number, bank change information, volume, pan, and four assignable controllers.

Real‑time controls include string split and playing position split, both of which require that a second program number be specified for the second sound, and the guitar loudness envelope itself may also be converted to MIDI controller data.

Once set up, the G50's tracking is surprisingly good, but it isn't totally foolproof.

Accessing and setting up the various parameters is quick and reasonably intuitive, but I was rather confused by the program change section, which can be set to 'off' to mute the MIDI output completely, but can't be set so as to send no patch change data at all, unless the MIDI note data is also muted. In practice, this means you either have to play by the G50's own rules and program your synth patch numbers into the G50 programs, or you have to disable program change on your synth. If you don't do this, every time you pick a new program on the G50, a MIDI program change will be sent and your synth will change patches.

The split and picking position features work well, but the success of the 'position' split depends on your synth. Whenever you move across the section of string that decides the positional split, the G50 sends out a patch change (which you have to specify as part of setting up the split), but as the note and patch change data are sent at effectively the same time, if you have one of those synths that takes a finite time to change patches, you could lose a note every time you switch sounds.

The positional split‑point itself can be varied, via the setup menu, from very close to the bridge to a few inches away from it, and though no mention is made of how this works, I can only assume that it is related to the harmonic content of the string.

On The Right Track?

Now to the serious stuff — the tracking. Getting any MIDI guitar to track half decently is firstly a matter of getting the divided pickup mounted securely and at the right distance from the strings. I found that, with my Strat Plus, there was no spare room for sticky pads between the pickup and the scratch‑plate at the top string position, and only a little spare under the bottom string, so I stuck the pickup down with double‑sided tape for test purposes, which left it about the right distance from the strings. To make a permanent fixing, it would have been necessary to counter‑bore the scratchplate under the mounting screws to accommodate the strings.

Once set up, the G50's tracking is surprisingly good, but it isn't totally foolproof. As with other MIDI guitars, errors are more likely to occur when several strings are being played at the same time, or when the tremolo arm is being used — presumably because of the amount of controller data flying around. Indeed, performance is really only acceptable in the one‑string‑per‑channel mode — working in single‑channel, poly mode precludes hammer‑ons, and notes in scales occasionally play a semitone flat. You also have to be quite careful not to strike harmonics with the side of your picking thumb, something that guitarists tend to do without even thinking about it. Failure to observe this can lead to false note detection, whatever mode you're in.

However, apart from these potential pitfalls, the tracking is quick and generally accurate, and the positional cross‑switching works like magic. There's no obvious delay, though if you try to play notes too close together by trilling on the same string, some notes invariably fail to register.

Summary

Given the extraordinary technical problems of converting a guitar's output into MIDI data, Yamaha have succeeded in building an effective, sensibly‑priced guitar‑to‑MIDI interface with some nice controller functions thrown in. It isn't perfect, but providing you play reasonably cleanly, and take the time to set the system up properly in the first place, the results are pretty good.

We're often asked about whether MIDI guitar systems can be used for sequencer programming, and yes, it is possible, but there are several factors you need to be aware of. One is that the notes you see in the edit pages may not always be the notes you played. For example, a hammer‑on is recorded as a single note followed by lots of pitch‑bend information, not two discrete notes. For parts that don't require pitch‑bend, Chromatic mode produces sequences that are generally easier to edit, in that you don't have endless streams of bend data surrounding each note — but then you lose the ability to perform bends. Hammer‑ons, however, work fine in Chromatic mode. When limited pitch‑bend is required, Auto mode is sometimes more satisfactory than simply leaving Chromatic mode switched off, as the G50 will switch from Chromatic mode when you're playing chords to non‑Chromatic mode when single notes are being played.

Another factor to consider when recording data in the 'one‑channel‑per‑string' format is that you have to find some way to record on six channels at the same time, and while some sequencers do this easily, others require more fiddling about. Personally, I think all sequencer packages should have a dedicated MIDI guitar recording mode, but until their designers feel the same, we'll have to do it the hard way.

People will inevitably ask if there's any real difference between the Roland GR1 and GR09 and the Yamaha G50. Roland's system has the advantage of internal sounds, and tracking when using the internal sounds is exceptionally fast and surprisingly positive. When you try to access external MIDI sounds, however, the performance of the Roland systems falls off quite noticeably, so I feel Yamaha may have a slight edge if you need to work with a sequencer or external MIDI modules.

Somehow, I don't think we've heard the last word yet when it comes to MIDI guitar systems, and though the G50 is impressive, it still doesn't feel or respond quite like a guitar — you have to discipline yourself to meeting it halfway. If you're prepared to spend a little time getting to know it, you can achieve spectacular results — it's good, but it's not quite magic!