And not just that, but virtual “Nashville tuning” too…and 18-string guitars…with lots of audio examples!

by Craig Anderton

One of the reasons I got into Gibson’s newer guitars is because of the way they implement hex outputs (i.e., each string has its own audio output). Although Gibson isn’t the only company that makes guitars with hex outs, they’ve taken the concept seriously and keep improving on it.

This all started with the HD.6X-Pro back in 2007 (the guitar that’s been in my avatar all these years!), which used a magnetic pickup; since then, the Dark Fire, Dusk Tiger, Firebird X, and Les Paul X have all had hex outs based on piezo pickup technology. The X-series guitars are my favorites, because they’ve increased the isolation between strings by reducing crosstalk even further.

The obvious use for hex outputs is hex processing, like the kind of super-clean, almost synth-like sound you get from distorting each string individually. But using a piezo pickup means it’s also possible to obtain very convincing acoustic guitar sounds, and with hex outputs, you can apply SONAR’s offline pitch transposition to emulate acoustic 12-string guitars as well as 8-string basses, “Nashville” tunings, and even guitars that don’t exist—like a 12-string where the top two strings aren’t doubled, but also transposed up an octave. Or how about an 18-string guitar, where you add another set of six virtual strings transposed up and an octave, and another set transposed down an octave

With SONAR you could transpose using Acidization or the Pitch Shifter plug-in, but the fidelity is problematic when you’re transposing up or down an octave. However, the offline DSP fidelity is definitely up to the task. The only limitation is that it’s not real time, so you need to apply the transposition to a recorded file, then invoke the DSP and wait for SONAR to crunch some numbers to do the transposition.

I usually use the hex outputs from Gibson’s Firebird X, although any guitar with hex audio outs will work. I record each string in its own track, which results in six tracks of clips, and then clone the lower four strings (low E – G) to create additional tracks for octave-shifting.

Fig. 1: The Transposition dialog box is set up to transpose one octave up, using the Mix-Advanced algorithm.

Click on the cloned clip with the low E, then choose Process > Transpose. When the Transpose dialog box appears, check the Transpose Audio box, enter the transposition Amount (in this case, +12 to generate the octave higher string), then choose the transposition Type.

There are five pitch transposition algorithms: Solo, Solo Bass, Solo ocal, Radius Mix, and Radius Mix-Advanced. Solo, Bass, and Vocal are designed for monophonic lines, while Radius Mix and Radius Mix-Advanced are optimized for polyphonic material. However, I’ve found that even with solo guitar notes from a hex pickup, the Mix algorithms sound the best (the tradeoff is that they take longer to crunch numbers than the Solo algorithms).

Choosing the Mix-Advanced algorithm adds two more parameters—Pitch Coherence and Phase Coherence. The latter is important mostly for surround, so we can safely ignore it. I’ve experimented with Pitch Coherence, and aside from vocals, haven’t yet found source material where it makes a significant difference in sound quality.

We still need to transpose the other “octave” strings. Click on the cloned clips for the A, D, and G strings, and transpose them up an octave. For a standard 12-string sound, insert a chorus for the B and high E to double and detune the string somewhat, which is what happens with a 12-string.

For the final touch, with a real 12-string the pick hits the octave strings a few milliseconds later than the regular strings. It’s easy to emulate this effect by delaying the cloned, octave-higher clips by about 20 milliseconds. For the B and high E tracks, simply adjust the initial delay for the delayed signal.

Check out the audio examples: 6-String.mp3 has the original hex pickup tracks, while 12-String.mp3 includes the electronic trickery…which amazingly, doesn’t sound like trickery at all.

Pseudo-Nashville tuning, too. “Nashville” tuning uses the top two strings of a standard set of strings, but the octave strings from a 12-string set for the bottom four strings. This means the low E, A, D, and G strings are an octave higher than standard (it’s also possible to buy Nashville string sets, like d’Addario’s EJ38H string set for acoustic guitar or EXL150H set for electric guitar).

Nashville tuning is used mostly with rhythm guitar, and gives a bright, present sound that doesn’t get in the way of lower register instruments like bass, or the low notes on a piano. A good example is Fleetwood Mac’s “Never Going Back,” the beginning of the Stones’ “Wild Horses,” Pink Floyd’s “Hey You,” Tom Petty’s “Free Fallin’,” and others.

To do Nashville tuning, select the clips for the low E, A, D, and G strings, then transpose each one up an octave. Imagine…you don’t even need a separate, dedicated guitar, or have to change your strings! This is definitely progress. What’s even better is that I prefer a modification of Nashville tuning where the G string is not tuned up an octave. No problem: I just transpose the bottom three strings up and leave the G alone..

The audio example Nashville.mp3 uses standard Nashville tuning, while for comparison Standard.mp3 is the standard guitar tuning. Nashville Lo G.mp3 is the variation on Nashville tuning mentioned above, with the G string dropped an octave.

Learn more about SONAR X3.