It was probably about 1970 when I had this idea. I'd had the usual problem of getting feedback from a miked acoustic, and explored the whys and wherefores all I could. I also had seen Jimi playing at Woodstock, and got a feel for what could be done with feedback if only one had cpntrol. So in the last couple months, 40 years after thinking about it, I finally did it. Can't say the wait was worth it, but I can say I've got an awesome way to scare the neighbors.

Take one Fender/Squire 3/4 size student hollow body. Get the catalog from Parts Express and start looking for surface drivers (ie. contact speakers). Drop an old Fender single coil pick up min the sound hole. Find the page in P.E. that has these drivers in them. Get a pair of 25mm and a pair of 12 mm drivers. Put one of each size3 on the back from the Squier. Attatch leads to the drivers from the amp's output (aux speaker out, not a headphone out). Now plug that cheap acoustic into the amp, and plug the amp's pre-out into the two drivers. Turns it on and crank it. The pick up gets the signal, passes in the the amp, which drops a copy up a monitor line to a small amp driving only these surface drivers (a computer speaker amp worked perfect. So it's getting pumped into the back of the sounds board just exactly that which is heading for the amp's speaker. Lag time to maximal feedback, close to zero. The onlly problem (if it is one) is that the sound coming out of the PA speakers is exactly the same as what's pouring out of the guitar -- literally. Sure, there's some awesome feedback happening, but there's also what sounds like a radio inside the guitar and you're playing alone.

Anyway,. with a bit of practice I can mute, muffle or make active use of these sounds driving the guitar. I can make it act like a little echo box and play through undistorted, or overdrive and the amp for growl and at the speakers for scream. nd the look on peoples faces when I drag out this old box, but then these sounds come from it.
congrats, you took a technique already in place and essentially taped it to the back of your guitar. sorry if im misunderstanding the importance of this, maybe a sound clip or video would help?
My Gear:
Gibson Faded Flying V
"Dante's Inferno" Iceman
Fender Hot Rod Deluxe 112

Quote by freedoms_stain
I can't imagine anything worse than shagging to Mark Knopfler.

Maybe shagging Mark Knopfler, but that's about it.
Quote by TK1
congrats, you took a technique already in place and essentially taped it to the back of your guitar. sorry if im misunderstanding the importance of this, maybe a sound clip or video would help?

Video wouldn't do much. A sound clip might help, but I'm hoping a description explains enough for understanding. Besides I don't have recording capabilities at the moment that would suffice.

I took a crude approximation of a feedback loop and turned it into a full bandwidth feedback loop, so the instrumentation involved can make full use of it.

In the technique already in place a guitar reverberates to one or at most a few major harmonics of the loudest notes being played. You can get it to switch between different harmonics or ride along on one as you let it build, stretch it or pick some notes that hit in the harmonics window enough to make it change.

With mine I have control over what affects it. I can feed it any or all channels. Rather than reverberating with a few harmonics, the driver on the sound box turns the guitar into a fairly full spectrum speaker -- you actually hear a good representation of what's driving it. I can use the vocals as the driving signal and get feedback from them rather than the guitar's notes. I can use filtering etc. to pick out what notes I want to emphasize. I can play the bass signal into it and finger the matching chords, and have the bass guitar "strum" it for me (and in a favorite variation of this, use a drumstick to pitterpat very fast strum-like stuff on the strings simultaneously -- I now have 3 "hands").

I can tune the guitar to the key chords of the song and have the music drive it and darn near play it as a proxy, in much the same way the sympathetic strings on a sitar react to notes played tuned to or harmonic to them. Or consider the talk-box like Frampton made famous, with a speaker playing the guitar sound into a tube that runs into the mouth and you mouth the words using the guitar for sound. Turn it around, sing into the mike, amp that and play it back into the guitar, the guitar reverberates with your voice (which can be picked up by mike) and resonates the strings which you can then fret to pick out harmony to your own singing while simultaneously strumming the backing chords.

Comparing this to a guitar picking up whatever it's most sensitive to and feeding back the few resulting harmonics is like comparing an electric guitar and amp to a washtub bass. The standard technique adds some noises that a very few can learn to incorporate into the music. Mine starts as music, makes more music in the process, and can serve as additional background sound or another instrument, can be played completely and fully instead of punching out some additional harmonic tones, and can be used in ways that other instruments work but guitars never have.

Try to play it once and you get the difference. With a guitar you make it play notes (and can reinforce them with some feedback if you want). With this, you can play it also, but to play the feedback you have to learn to un-play it. You have to let the stuff you want to come out pass through it and block the rest of the signal. Imagine trying to play a keyboard with the keys all stuck down and you have to lift the ones you don't want to sound, all with one hand, while the other plays the same keyboard acting normally. With the normal arrangement if you dampen the feedback you have to restart it and let it build again. With this, it is constantly driven and you can play it, stop it, play it back and forth rapidly as though switching between instruments or effects,

What good is it? What good is a "bass" that's just a collection of laser beams that if you break the beam by sticking your hand in front of it, it plays that note? Ask Jean-Michel Jarre. This is experimental musical instrumentation. Basic Research need not concern itself with applications. They arise from the development. But if there was ever an instrument that could shock and awe an audience, it's Jarre's laser bass. About this, we'll see. It's only been a month.
I need pics of this soo bad. And a video would be amazing if you could get it. what good is experimentation without documentation?
no sir away a papaya war is on
Quote by the_perdestrian
I need pics of this soo bad. And a video would be amazing if you could get it. what good is experimentation without documentation?

Hey, I'm the scientist here. I can document out the wazoo.

I'll work on pics. Fair warning, it's ugly. But so was the first laser. And the first transistor. Seen them both. When they were new. I'm gonna stop there with that line of discussion.

Here's the 25mm driver:

It's stuck to the back of the box in the middle of the larger part of the body. The 13mm driver (wired series so I don't fry them) is stuck to the back in the middle of the upper 'bulge'. The wiring is 24 g clear insulator speaker wire. Rather than drill a hole in the body, I ran the wire into a pill bottle and put the 3.5mm jack in the bottom of that. It hangs from the strap peg on the bottom. The 1/4" jack for the single coil pickup is in the top of the pill bottle, and it just sits in the sound hole like any drop-in pick up. All the wiring is external, hence the ugly. No volume or tone controls except on the amp (for the pick-up), and the computer speakers amp I use to drive the surface mount drivers (main amp headphone out to computer speakers amp input).