Infinite Improbability

This is the story of two men's quest for infinity. Or rather, infinite sustain to a Fender Stratocaster Electric Guitar (copy). It was a bright July day, with swarms of hoverflies descending on the South Suffolk/ North Essex area. Sunny Brightlingsea was about to embrace infinity.

The Theory.

The theory behind the experiment goes something like this:  The electric guitar uses the Piezo-electric principle to generate sound - the disruption caused by metal strings moving within the magnetic field of the guitar pickups (essentially wire coils), induces a flow of electrons which is normally amplified by standard amps and stuff. 

But what if you were to take that signal and feed it back into a separate piezo-electric generator in close proximity to the sensor? The sensor would then detect the signal in the generator, which originally came from the sensor. Also, the strings themselves should be moved by the magnetic field.Uroboros for guitar!  There are several companies that offer this effect, but they are all pretty pricy.

Mr Jo Searles, aka Calaco wanted to give the homemade method a try.  I was along for the ride, as I've had plenty of experience of wiring up weird things.

The total component cost was about £2 plus whatever Jo had lying about in terms of spares.

That was the theory, the practice went a little like this.

The Donor

A Fender Stratocaster Guitar (copy).  A bargain at £80, and quite a nice instrument that Jo bought specifically for the experiment.

I had already done some experiments with a Dimarzio Hotrail pickup, and I could get the pickup to make strange noises when placed in close proximity to sources of electromagnetic noise (an electric fan, my PC's CRT). It also seemed to be a fantastic metal detector!

The Practice

Now was the time to combine theory with the practice of the preliminary experiments.

The strat was quickly stripped down.

The scratchplate where all the electronics are mounted was disconnected.

The hotrail with a small op-amp was screwed into place.

The hotrail fed its signal back into itself and remained a fantastic metal detector.

This sucked.

 

After much discussion we disconnected the hotrail as an input and wired the other pickups into it. It should now only act as a generator and not feed back horrendously.

It fed back.

We tried something else, I can't remember what exactly.  But with the guitar lying on Jo's kitchen work surface it sustained beautifully, a rich warm sound. Unfortunately this was not electronic but from the kitchen cabinet itself.  Damn!

It was time to do some thinking.  The best thinking is always done on a trip to the shop (works for me all the while).  Perhaps its that whole daylight and fresh air thing that I really ought to get more of.

We began to suspect that the signal was too weak, so an additional amplifier (the smokey fag packet amp) got hooked into the circuit (yellow cable top right).

It fed back again! We even tried fitting the pickup upside down, to no avail.

Again this really sucked.  We looked a load of stuff up, but got nowhere fast.  It seems that the infinite sustainer still remains in the hands of the professionals.  It is my suspicion that the sustain was working - but it was working as feedback because the signal was not shielded, and the electro-magnetic balance was impossible to achieve.  We either had something too quiet to be heard, or so loud it fed back as really nasty noise instantly.

I think this expression says it all. We no understandy.

The Change of Plan.

Jo fortunately had a schematic for a strat wiring alteration known as the "super seven".  This variation increased the number of pickup selections from five to seven.

It worked! We now had a strat which we could turn on all three pickups at once, or could turn on the two at opposite ends for a telecaster effect. You can see an additional switch on the strat next to the volume and tone controls. It was quite cool!

And it worked!

Watch this space for further projects.

---