Epiphone SG - First attempt at fitting a Roland GT3 Kit

BACKGROUND

I'd been toying with the idea of getting a guitar synthesiser for a few years and finally decided to take the plunge to give myself something to do whilst recuperating from an operation. I found a Roland GR33 at a reasonable price on eBay but it didn't have the pickup with it. The choice was then to look out for a GK2 or GK3 removable pickup and fit it to one of my existing guitars or to buy a GT3 permanent installation kit and have a go at fitting it.

I decided that rather than fit a semi-permanent pickup I would go the whole hog and dedicate a guitar for use with the synthesiser so started looking around to see what might be suitable for a fairly simple installation that didn't involve the use of a router. I've got one but my skills using it are limited.

The pickup and the 13 way cable were ordered from DV247.com and arrived the next day. (I've bought a number of bits and pieces from them and have been very pleased with the value for money and the speedy delivery).

I found a couple of pages on the web showing how the installation is done professionally on a Strat and it looked a bit scary. I decided that I would look around for a fairly cheap second hand guitar which I could modify accordingly and if I did make any mistakes, slip with the drill etc then nothing expensive would be lost.

I settled on a basic guitar that didn't have a high gloss lacquer finish (which would be very easy to damage), had a simple pickup layout, no tremolo unit and a plain front ie. no scratchplate.  Two guitars that matched these criteria were the Epiphone Custom SG Special and the Epiphone Les Paul Special. I had another look on eBay and found an Epiphone Custom Shop SG. I'm not a guitar connoisseur but I've very pleased with the guitar that I've ended up with. The action is not bad, it is not too heavy, balances well, and sounds good.

THE ORIGINAL GUITAR

Epiphone SG - before the  modifications

Epiphone SG - Original wiring

THE MODIFICATIONS

I started by removing the strings, the neck and all the hardware, having first taken a picture of the original wiring. You'll need to be confident using a soldering iron for this bit and the reconnection later.

My biggest concern, before I started, was how to get the cable from the hex pickup into the controls cavity. From the picture below you will see that the pickup cable has a pre-wired multiway connector fitted. I was toying with the idea of removing the connector and then refitting once the cable was in position. As luck would have it the hole that Epiphone had drilled between the pickup cavity and the control cavity is just big enough for the cable, with its connector, to pass through. That was a major headache out of the way. I had to nibble a small indent at the back of the pickup cavity so the hex lead could pass under the humbucker surround but that was all.

Roland GT3 Kit

The contents of the Roland GK3 internal installation kit are shown above. Most components are connected using pre-wired multiway connectors. The only soldering that is required is an earth wire which connects to the common terminals of the switches and the guitar output from the original jack socket.

The next big decision was the exact layout for each of the controls and the placement of the 13 pin socket.  The original guitar had one volume and one tone control working across the pickups. I decided to dispense with the tone control and use the redundant hole to take the synthesiser volume control. I then marked out the remaining 3 switches and the LED accordingly, using masking tape, and drilled the correct size holes. The patch change buttons are both push fit, the toggle and LED are held in place with nuts and washers.

Probably the most daunting task was marking out and then cutting the hole for 13 pin socket. At this point one slip with the drill could do serious damage so it's worth taking your time. I decided to "stitch" drill a series of small holes around the edge of the hole and then join them up to give me the large, rectangular hole finally required.

Marking out for the new 13 pin socket

Socket hole drilled out

I used a file to finish off the hole but it doesn't need to be too tidy as the socket mounting plate hides it.  The mounting plate has plain holes drilled in it which means that the fixing screws would stand proud from the surface. I very carefully countersunk each of them and then fitted the plate with the smallest crosshead screws that I could find.

New socket installed

New control layout

I was now ready to mount the hex pickup which is supported by two wood screws and springs. You adjust the pickup by screwing them in to the right height. The Roland instructions show you what tolerance you need between the pickup and the strings to get the optimum performance. There a small grub screw in the middle of the pickup so that a degree of curve can be introduced to match the guitar stringing.

The final task is the internal wiring. There are a number of soldered connections which need to be made first and then the motherboard can be plugged in using the multi-way connectors. The circuit board is very small and insulated by a plastic wraparound. Once plugged in it can be turned over, laid into the cavity and the backplate fitted.

New wiring with multiway connections to PCB

The pcb fits nicely on top of the controls

It's then time to see if you've managed to install it correctly. I'd had my GR33 for 3 weeks before I modified the guitar and had been unable to try it out so it was double anticipation. It was with a certain amount of trepidation that I plugged in the guitar and switched on the synth. It worked first time and I was playing a Hammond, from the guitar. Amazing!

THE FINAL RESULT

Epiphone SG - Original

Epiphone SG - Modified

As a finishing touch I added a couple of new speed knobs. I'm really pleased with the final result as the guitar still retains it's classic, uncluttered appearance.

If I was a better guitarist I would also include a sound file but I wouldn't inflict that on anyone. Suffice to say that the in-built Roland sounds are pretty decent. Bearing in mind the GR33 unit is some 10 years old then the sounds can be described as "classic".

Using a midi-to-USB cable the GR-33 can be plugged into a Mac and used to drive software instruments. This opens up all sorts of possibilities. I've been using it with Garageband to drive G-Force's M-Tron Pro software which gives me all the classic Mellotron sounds from my guitar fretboard. The only thing to watch out for here is latency, ie the time it takes for the computer to process the incoming signal and send it to the soft instrument. So far it's not been too bad but I wonder if rather than using a cheap midi-to-USB cable a more expensive unit would give better performance.

Some guitar synthesiser users seem to suffer from tracking problems and unwanted notes. I think if you start with the attitude that whilst this is pretty amazing technology it isn't perfect then you will not be disappointed. By setting the tracking parameter in the voices to match the instrument being played ie. if you are playing a keyboard voice then set the tracking to semitones to match the keys, then this will help produce a realistic sound.

I hope this information has been useful. Any questions then please contact me.