DSP tuning not only lets you play in tune, it provides you with alternate tunings

by Jon Chappell

The Antares Auto-Tune circuitry (inset photo) fits on a board no larger than a business card and comes installed on the new Peavey AT-200.

Antares is the leader in the technology referred to as auto-tuning, also known as pitch-correction, and famously abused in T-Pain and Cher songs, but which is an indispensable production tool when used sparingly, to correct the intonation of a slightly out-of-tune note in an otherwise perfect take.

Recently, Antares introduced Auto-Tune for Guitar, which promised to do for six-stringers what their vocal version had done for singers. Antares’ technology manifested itself at the 2012 Winter NAMM Show in two different configurations: the high-end Parker Auto-Tune MaxxFly and the affordable Peavey AT-200 (under-$400).

Using a different system, but still applying DSP to tuning is Roland, who, also at the show, introduced the latest in their guitar synth line, the G5. In fact, at the demo, Skunk Baxter played A/B’d the straight guitar against the DSP-modeled version, and no one in the audience could tell the difference. To be fair, that was much the same reaction at the Peavey booth: the DSP guitar sounds a whole lot like the passive (unprocessed) guitar signal.

And not new for the show, but only about a year old are the new James Tyler Variax guitars from Line 6. One of the upgrades of this line is that the a dedicated knob has been added for alternate tunings. (Previously you had to access this functionality through software.)

This embarrassment of guitar DSP riches means it’s time to start examining the whole notion of DSP-based tuning and how it differs from the physical retuning of the guitar, as we’ve seen in the Gibson Robot Tuners and Trev Wilkinson’s ATD bridge. We'll highlight the two newest guitars on this front, the Peavey AT-200 and the Parker MaxxFly.

NO STRINGS WERE HARMED IN THIS DSP TUNING

First things first: In a DSP-based system, the strings don’t actually change tension. If the strings are out of tune, they stay that way. The sound coming out of the pickups, however, will be perfectly in tune. So a DSP-tuned guitar relies on the electronic output to be “heard” in tune. This means that if you can hear the strings acoustically (say, if the amp volume is way down), you’ll hear that the vibrating strings and the output pitch are not in tune with each other. This is ignorable if your strings are only a little out of tune, but it’s more distracting in the distance is pronounced, and certainly if you’re in an alternate tuning (more on that later). The cure is to turn up the volume or wear headphones to mask the acoustic sound of the strings. Obviously, on a solidbody the acoustic sound is not as significant as it would be on a guitar that projects more acoustically, like a semi-hollowbody.

What’s true for an open string also goes for the intonation—the ability for an in-tune string to say exactly on pitch as it’s fretted up the neck. For example, let’s say you have a G string that frets sharp at the 12th fret (when compared to the open-string harmonic). No matter how perfectly in-tune the open string is, it will go out of tune as you fret up the neck, getting worse as go along.

Well, Auto-Tune will fix that phenomenon, on the fly, meaning you can put off having that setup job by your guitar tech. This opens up the possibilities for slide guitar, where raising the action of your strings messes with your physical intonation. If the intonation (as well as the open-string tuning) is corrected (as Auto-Tune does), then it mitigates that setup issue, and allows you to go back and forth between a slide setup and a regular, fretted one without also having to adjust the physical intonation. That’s pretty cool.

The basic version of Auto-Tune, as found on the Peavey AT-200 will both tune your strings and keep them intonated (or staying in tune as they’re fretted). It does this by putting an individual sensor under each string and giving it its own discrete signal path. If you’re worried about the constant tuning-monitoring interfering with subtle variations of pitch, like vibrato or quarter-string bends, well Auto-Tune has thought of that. According to Antares: “The Antares Solid-Tune™ intonation system constantly monitors the precise pitch of each individual string and electronically makes any corrections necessary to ensure that every note of every chord and riff is always in tune, regardless of variables like finger position or pressure. The technology is even smart enough to know when players intend to manipulate pitch, so bends and vibrato sound as natural as they always have.”

ALTERNATIVE LIFETUNINGS

That’s very impressive stuff for an eminently playable guitar for under $400. But Auto-Tune provides one more function: you can get alternate tunings out of it, in a sort of work-around way. For example, if you fret the 6th string at the 2nd fret, put the guitar in tuning mode and then strum, the guitar tunes itself to standard tuning, based on your fretting the 6th string. That means once you release your finger, the 6th string now sounds as a low D—voilà—instant Drop-D Tuning.

If you take this a step further, you realize that you can create other alternate tunings. To create Double-Drop D (the outside strings are both tuned down a step to D, two octaves apart), simply fret the outside strings at the 2nd fret and tune up. To get open D—the tuning you need to play The Allman Bros.’ “Little Martha” and the Black Crowes’ “She Talks to Angels”— fret the guitar this way, from low to high: 2-0-0-0-2-2. See Figure 1 for a chord diagram showing how you’d finger this.

Fig. 1. How to finger notes on the neck to get alternate tunings with Auto-Tune.

You can create any alternate tuning this way, as long as the pitches are lower than the ones found in standard. To play DADGAD and open G (D, G, D, G, B, D, low to high), finger the left-hand (low to high) this way: 2-0-0-0-2-2 and 2-0-0-0-2-2, respectively (see Fig. 2).

Fig. 2. Fingering DADGAD and Open-G tunings.

The only drawback to this is that you can’t create any tunings where the strings are higher. For example, to get open E (E, B, E, G#, B, E), where the 5th, 4th, and 3rd strings are raised, you’d have to tune down to open D and use a physical capo. And that’s the other thing the basic version of Auto-Tune can’t do: act as a virtual capo. So to get mandolin- and ukulele-like qualities, you need an actual capo.

ON THE HIGH END

If you opt for Antares’ Auto-Tune as found in the Parker MaxxFly (Fig. 3), however, you get the full treatment of tuning features, including storable alternate tunings where the strings can be retuned either higher or lower. Here’s a list of tunings you can get with the press of a button:

Drop D
DADGAD
Open G
Open D
Open E
Seven string (low B doubled on lowest string)
Twelve string
Bass guitar
Octaver
User-created tunings

Fig. 3. The Parker MaxxFly has a high-end version of Antares' Auto-Tune.

As well, the MaxxFly’s version of Auto-Tune includes a virtual capo where you can go up (not possible on the Peavey) or down (available only through a work-around) easily, up to a full octave in either direction. Virtual capos have an advantage over their physical counterparts in that the entire full range of the neck is preserved. A real capo narrows the available playing range.

The Parker MaxxFly also boasts pickup modeling and digital tone control for an unlimited variety of tonal shadings. You can select a specific guitar with a certain pickup configuration, and then switch among those pickup combinations, just as you would on the real thing. In addition to the modeling components the MaxxFly’s Auto-Tune’s function includes a tone control that boosts or cuts the frequency response of the modeled pickups for more organic control, once you’ve dialed in your sound.

AUTO-TUNE FOR EITHER BUDGET

Antares Auto-Tune for Guitar is built in to both Peavey and Parker guitars. Because the systems are software based, upgrades are easy to implement, and they can be controlled by any MIDI source—from a footswitch controller to iPad and iPhone devices running Auto-Tune control software. Whichever guitar and Auto-Tune version you choose, you get perfect tuning, Antares’ Solid-Tune intonation system to ensure every note of every melody and chord is in tune.