# {Wavenumber LLC}

[Dream|Design|Deliver]

$-T\sum_{n=1}^{\infty}\frac{n\pi}{L}a_{n}$

Although the piano/keyboard was my first musical instrument,  the electric guitar has always fascinated me. While the piano is enabler of complex creations, it (to me) is a very "linear" instrument.   The keyboard is easy to teach.   There is one location for each note.   Expression and dynamics are simple.  The guitar on the other hand is a "non-linear" instrument.  There are many places to fret the same note, each with different timbre.  There are many approaches to the dynamics of the attack and fretting style which yield awesome results!

One thing has always bugged my about the guitar is in how it's engineered.  Not so much in the design and build quality of the physical components (neck, body, etc) but in the sensing approach.   Let's face it, electro-magnetic pickups are horrible sensors.   Couple that with the fact that the signal is carried over an 80 year jack design using an unbalanced transmission technique.  It’s 2012 and we can do much better.   I place a lot of the blame on this ridiculous notion that if the guitar technology wasn't design in the 60's it is somehow inferior. Open a recent “Guitar Player” magazine and you will see very little has really changed. I even see “vintage” batteries and cable being sold by online retailers for your “vintage” pedals.   I find it almost comical that 99% of the (digital) electronics technology out there focuses on modeling amplifiers designed in 60's.   If you want a Vox then buy a Vox.   I can certainly understand being pragmatic and wanting all those tones in a single box but once again it's time to rethink what our DSP technology can do. Line 6 has the Vox model figured out. I am done with modeling the past. Let’s think about what a guitar can be. Let's stop recreating what “was”.  It's been figured out many times over.

I have been pondering this general topic for many years now.   Is there a better sensor?   Should signal processing be built into the guitar?   Should we rethink the amplifier?  I.E.  can we go digital right to a switching power stage with I2S? New cabling?   A few years ago I tore the pickguard off a Carvin Bolt-T for the heck of it.   I thought it be cool if the entire body was built up with layers of PCBs! It would look very, very cool.  While that concept may be a little wild and ahead of its time and much tamer version came to mind.   What if the pickguard IS the tone control?

I used this question as a design example in an FPGA course I taught at PSU in 2010.  We looked at how we could design an FPGA on a PCB board for this application.   I did quite a bit of work on it and it eventually sat.   There was the expense of prototyping the design,   I still needed external A/Ds,   BGA assembly......   Then I saw the ad for the Freescale Make It Challenge.  A winning design paper would get me \$1000.   After I saw the capabilities of the Kinetis devices,   I knew that was a great solution.   Built-In ADCs (you certainly DON’T need 24-bit if you can design good measurement circuits),   built-in touch sense inputs, plenty of DSP horsepower,  next to free tools......   I then decided to rework my solution.    At this point you should probably just see what I came up with the contest.   The video demo had to be short for the contest but I created a longer "deep-dive" to get into the technical details.

Having a graduate degree in Acoustics,   I thought some explanation of the theory of the pickups would be big plus!

As you can see the  LEDs, touch sensors and piezos make a cool solution.   I am very happy with using AES3 as a transport format.    Balanced line digital!    I am still undecided on the Ethernet cabling (though Neutrik makes some nice rugged housings ). The piezos are extremely clean and I can apply some DSP theory to get whatever I want.  I didn't have it ready in time for the videos but the guitar now has a nice octave effect patch.  Unfortunately for me I did not win.....   :-(     But I did recieve some decent cash to prototype my concept.  Who knows what other opportunities may pop up.

Although I certainly don't see the Active Pickguard as the end-all be-all all solution, it certainly was a great experiment!  I have figured out in my own mind where I want to go next. The piezo pickups are the way to go (IMHO). Getting rid of 60Hz noise with a sensor that exhibits some “real” SNR is well worth the transition pains to the new technology. AES3 is the way to go for transport but I am still thinking about the best cabling approach. I am now working on Version 2 as well as an amplifier that can receive the digital signals directly. I am even considering a “kit” so one could retrofit their own guitar...... Stay Tuned!

ehughes & wavenumber ->net

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