Ghost Guitar

Sometimes you have an idea and you have to go for it, right? Well my moment of madness happened about 9 months ago, when I listen to my oldest and definitely one of my best mate’s latest song. He plays the blues, has played on TV, and is generally a bit brilliant. One thing I noticed was that guitar and voice sometimes misses a bit of Bass, but short of starting a band there is not much you can do. Or is there?

The idea I had was simple. Make the bottom two strings of a guitar into a bass and away you go. Obviously a guitar neck can not handle two bass strings, and obviously you don’t want to miss the versatility of 6 strings, so the idea is to octave the bottom two strings down electronically.

So far so good, So I took this idea to another best mate of mine, Andrew Gibson, and with a name like that he didn’t let me down. We started by building early concepts. No 1 was to see how difficult it was to build a guitar. We found it to be very difficult. So modding was clearly the next step. We took a cheap guitar (£20) and fitted a bass pick-up to it. In principle this works, but two issues became clear. There was a bit of cross talk in that the bass pick-up would have a faint sound from the 3rd and 4th string (but that can be stopped via a smart octaver). The other issue was that it looks ugly and unprofessional (not that we are professional, but the future owner of this guitar plays in public and has standards!).

So after months of research and trials Andrew found the Ghost systems from GraphTech. Calling them in Canada from the UK wasn’t cheap, but I had a ton of questions and I couldn’t translate what was on the web to what I had in mind. 20 Minutes later the guys from Graph Tech understood what I was after (not that they are dense. Lets just say with my ability to describe electronic and guitar issues I will not be writing for magazines any time soon). As my mate the guitar player is not into midi we had do go with an acoustic solution. For this the brilliant people at GraphTech even thought out a clever custom switch that allowed us to short out the signal from 4 of the Ghost pick-ups leaving us with just the two base notes. Brilliant!

To cut a long story short, it works a treat. It now has to be played by my musician buddy and he will have to tell us if we hit the mark. I include a bit of background on the build below with a couple of pictures, but overall it was not too bad. The build time including routing, fitting and understanding the system was under 12 hours, which included us working very slowly, very methodically and discussing every step. Someone who has looked into guitars and understands wiring could have done it in two,  which is pretty cool.

You can listen to the sounds the guitar makes below. The track is stereo and has different sections:

  1. unaltered magnetic sound (Ghost leaves the magnetic pick-ups unaltered) {0:00-0:12} – Stereo R
  2. Ghost pickups only (Ghost gives the guitar an acoustic timbre) {0:13-0:27} – Stereo L
  3. Magnetic and Ghost pick-ups in combo {0:28-0:43} – Magnetic R, Ghost L
  4. Bottom two strings on Ghost and all six on magnetic pickups {0:432-0:53} – Magnetic R, Ghost L
  5. As 4 but with the Ghost run through octaver {0:54-1:23} – Magnetic R, Ghost Bass L

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We can probably agree that I will never be the worlds greatest guitarist. But lets stick to the technical side. The fact that the guitar output jack is stereo does not restrict what you can do with it. On a mono cable you get still the option to select Ghost, Magnetic or combo as well as the 2 or 6 string split, but in order to run the octaver over the bottom strings stereo out makes sense, that way you can also adress a bass amp.

The plan is to do more of these. It is just a great system, and doing these mods will become easier the more we do.  Plans for the future include:

– Using a midi out for acoustic to bring phantom power to the ghost system and ditch the battery

– Making a midi capable instrument (I have my Palmbay in mind for that, but maybe I will buy another guitar for that – any excuse!)

The Build in pictures

Guitar opened for the first timeOpening the guitar for the first time was … how shall I put it… interesting. The guitar is well over 20 years old, is an Ibanez Blazer Custom and had far too many switches, all of witch creaked and didn’t really work very well. So when I opened it for the first time the dirt, dust and other waste materials were just half the story. Someone had obviously bought some cheap parts and replaced the selector switch. Being too large they had gouged out some material from the guitar, which left it looking rather poor. But age in general had also made the wires brittle. At this point Andrew and I decided to rewire the whole guitar from the ground up and replace all the pods, switches and so on. I have also a nice Fender Stratocaster which means I didn’t have to worry too much about this tired old piece. It was a great place to start the final prototype.refitting first before moddingSo this was the state of play after the basic refit has taken place. We will probably continue to work on this guitar for a while until we have gotten everything out of it. Only then will we think about tackling new guitars. You can still see the old tangle on the top right of the picture, while the main plate has the new components fitted. The Ghost system itself is basically a new set of string bridges that fit to the end-plate. Each one contains a build in microphone that picks up the vibration of the string and generates the appropriate note. One side-effect we had not calculated in with this method is that there is (like in acoustic guitars) cross talk between the pick-ups which is great for acoustic sounds, but is not so good if you just want to pick up the bottom two strings for bass.

We only found this out at the end, when the assembly was complete, but fixed it by simply sticking isolating tape between the 2nd and 3rd pick-up. It is of course possible to just fit two pickups, simply use a summoning board and wire it to the volume control, but you forgo the great sound of the acoustic guitar the ghost system generates for you and things become rather flat. The ghost system we ordered was made up of the pick-ups, the volume control, a quick switch (toggling, magnetic, Ghost and both), Two summing boards (one for the top 4 strings and one for the low e and a string ghost pickups) an electric short switch which allows us to drop one summing boards (in our config we are dropping the four) and some very useful instruction manuals.

It turns out that the body mods were more extensive than we had initially thought. The ghost system was not the main issue either, it was more down to the update to the old components that had a negative impact. Almost every component has grown in size since this guitar was made (we thought electrics had shrunk, but we must be mistaken). On the other hand these are nicely insulated, and do not make those horrible crackling noises :)

The largest mod was to find a home for the battery and the Ghost board itself. Now that sounds like a contradiction to what I said earlier, but as mods go it was simple and not a lot of effort. The routing job looks not too neat, but as it is on the back and covered by a plastic cover…. anyway :) What is important is that the front cavity is insulated with black paint, which stops interference. The ghost systems does not require this, and in fact can have issues functioning in that sort of place.

You can see here all the electrical components in place. We had to drill a hole between the main front cavity and and the back to form a channel for the main switch wires. We also drilled the plat with a metal drill to fit the Ghost pick-up leads through. We were very careful to earth everything as described in the instructions (avoiding earthing loops) and and so on. You can also see glue from 1984 here – something any museum would be proud of.

The bass side will need a bit more work as we think it would be great two solve two issues. One is the power supply. No-one like batteries for life performances. Just when things go well the battery will pack up. So we are thinking of a foot pedal arrangement that will allow phantom power to be supplied to the guitar, while the unit will also take stereo in, and offer a top of the range octaver, some reverb and maybe even a way to switch the sounds of the guitar via the pedal.

But that will be another project for another day.

Let me know what you think :)

PS:    Read GraphTechs blog on Frankenstein mods here. We are very pleased to make the grade.