So, this post may come over a something of a product endorsement, but it actually leads us back to the idea of a guitar having a digital footprint – its own trail of data, gathered over a lifetime of use, that makes it more useful of valuable.

We’ve been playing with an Audio Sprockets ToneDexter pedal. This is a rather clever preamp for acoustic instruments that improves the output of a piezo pickup by processing its signal to sound more like the instrument has been miced up. It does this by comparing the pickup’s DI sound to the guitar’s sound when miced up, and storing the difference as a ‘waveform’ that is unique for this combination of instrument and mic. This waveform can then be added back to the piezo sound to recreate the mic sound.

You can see details of how to train and use the pedal on the website. In short, we plug both the piezo pickup DI output and a decent mic into the pedal (in this case we’re using our trusty Shure SM81), put the pedal into training mode, and start to strum some chords. Over the next minute or so the pedal captures and compares the sounds from both sources and builds up the digital waveform that represents the difference between the two.

Next, we unplug the mic and switch the pedal into its play mode. We’re now just using Carolan’s pickup, but the ToneDexter adds the captured waveform back to this signal to generate a sound that is impressively close to that from the SM81. The net results is Carolan can sound like it’s miced up with a decent mic but without all of the hassles that come with this – feedback and not being able move around on stage or having to lug mics and stands around with you and use headphones when recording.

After experimenting with various mic positions, the best sound for Carolan seems to come from pointing the mic down the fretboard from the headstock towards the body of the guitar (while also rolling off the bass in the SM81 which is a neat feature of this particular mic). Here’s a quick video of four-way comparison test of:

• Carolan played through an AER Compact 60 amp with the pedal in bypass mode (the normal sound of its piezo pickup plugged straight into the amp)
• Carolan played through the AER Compact 60, but with the pedal in now play mode (i.e., with the waveform added)
• Carolan recorded in Apple’s Logic Digital Audio Workstation through the pedal, but in bypass mode (i.e., normal sound you get when you Direct Input – DI – recording)
• Carolan recorded in Logic, but now with the pedal in play mode

You can hear the difference to some extent through the amp (though the phone is also capturing some of the natural guitar sound too). It’s far more noticeable with the recordings in Logic. We think that this ‘Dextered’ sound would be great for running through a PA when playing live and that it is also useful for studio work, certainly when in the mix with other instruments or when recording quickly on the move (high quality solo recoding of just Carolan would still be better with several good mics carefully positioned as we saw back in Post 41).

So we put it into practice with Carolan’s latest recording project, contributing to a new song, Can’t Go Back, from The Phil Langran Band. This is a bit of an unusual outing as it features Carolan being played with a bottleneck (in an open D minor tuning). Thanks as ever to Phil for Song, to Frank McCarthy his electric playing and producing the video, and to Mark Walker and Alistair Bloomfield for their playing too. A pleasure as ever.

Finally, not only is the Tone Dexter a useful tool, but it also gives us a new and compelling example of the idea that a guitar has a digital footprint. Carolan’s wave form is presumably unique, reflecting its distinctive voice as an instrument. it can be backed up and transferred into other Toner Dexter pedals and potentially into other tools that might use the same technique. Back in Post 38, Post 41 and Post 57 we talked about how the details of recording set-ups might feature as part of the digital footprint of a guitar. Well the ToneDexter profile takes this a step further. It’s not impossible to imagine that all guitars might be sampled in this way and that new instruments might be shipped with waveform profiles that might even be periodically updated over their lifetimes as their voices mature.

An intriguing thought. In the meantime it’s back to some more Dextering for Carolan.