I haven't followed this thread for awhile, so please forgive me if what I say is redundant with what's already been posted.

Among guitar builders, there's the recognition that one can easily overdrive an acoustic guitar made from inferior tone woods.  That is, the guitar's volume will not increase past a certain point as the force of a strum increases.  The resonance of a plywood and/or poorly braced top breaks down at a certain strumming force.  Conversely, a sitka spruce top that has 12 or more quarter-sawn (straight) grain lines per inch that is well-braced (e.g. on a good Martin - even a 000 model, Larrivee, Gibson or Lowden) will project an unbelieveable volume of sound the harder you strum.  This sound has an amazing ability to cut thru the noise of a crowded pub during a performance - think about Robert Johnson playing his acoustic blues in noisy crowded bars and actually being heard: pre-plywood guitar days, probably a handmade instrument.

Here's the connection to this thread (I hope):
Mondrasek notes that:

This is the case with the acoustic guitar as well.  Each note actually builds in volume from the initial pluck as the resonant "echos" reinforce it.

The way I see it, The Observer's "aha" about Lee-Tseung's forced resonance has its important merits that tie in here as well, allowing us to observe the functioning of a guitar to show us the way to what some call overunity.

I'd like to take this a step further in noting Dr. Stiffler's insistence that "pinging" electricial impulses off the spatial energy lattice will allow additional energy to be "cohered" from the energy sea in which we live.  In fact, frequency is key in many inventions drawing on the ambient energy in all things and around us.  Think about Keely vibrating a circle of set frequency tuning forks around a plate of water, which is made to release a tremendous amount of energy as frequencies build thru "resonant echoes," "forced resonance." 

As a related side note, it is interesting that some recording studios like to have an Ovation guitar on hand.  The fiberglass body cuts out a lot of harmonics, producing a more pure tone for the recording engineer who's struggling with too many harmonics in an acoustic signal.  But might the ovation's "purer" sound reduce the energetically exciting quality of a guitar's sound?  This is one reason why altho' digital recording might be more tonally precise, it will never match the warmth of the old analog recording on vinyl and analog tape.  But I digress...

Understanding the mechanics of a well-built guitar can help us better understand the pathway to overunity, I believe.  A high-end guitar will have Sitka Spruce bracing - very light and very strong (strong enough for airplanes - remember Howard Hughes' "spruce goose") to support the top that moves with resonant echoes from the back and sides.  It would be interesting to see whether crystalline resins within the top's wood cell structures release electrical impulses in piezoelectric fashion in an acoustic guitar that has reached the proper frequency for doing so.  Can an acoustic guitar vibrating at the proper frequency release electrity? Does it not just figuratively, but literally electrify the air?  Is it an accident that European violin maker Antonio Stradivari might have ground up obsidian and put it into his varnishes to make his instruments sound better?  Is there a piezoelectric effect in better acoustic instruments that makes their sound richer, fuller and brighter?

Anyway, I leave a few points to ponder, hoping to build on those already posted -

resonant echoes
forced resonance
frequency and pinging
piezoelectricity

Might all these converge to help point us more accurately toward what some would call "overunity?"

I hope that something I've said might help move the ball a few inches down the field.

B

Spoondini,

Thankyou for you interest in this.

If you do amplify the Electric... that sound from the amp cannot reach the string...
           otherwise you will cause a feedback loop which will force the string to ring longer.
           Like when a rock star holds the guitar close to the speaker to make a note ring longer.

My guess is this is the situation you are talking about.
           The electric guitar must be unplugged, or unconnected to an amplified output.

           Now I say the Acoustic Chamber does Amplify the string's wave, hense a feedback loop is created.
           This is why the Acoustic rings longer. ;o)

Seriously.... Haven't you ever picked up an unplugged Electric Guitar at a party and wanted to show off?
                         And found there isn't a chance anyone is going to hear you?

My question to you is How does the Resonant Chamber of an Acoustic Guitar work to produce a louder sound?

Regards,
              The Observer

Observer,
    Of course I recognize that an unplugged electric guitar is quieter than an accoustic guitar.  Where I disagree is that the string vibrates for a shorter amount of time(it's actually much longer, I just compared - but both instruments were plugged in to make a direct comparison).

What you need to recognize about hearing is that it's much like vision.  When you watch tv, you see one continuous moving picture and not the individual frames.  Sounds are also in 'frames' determined by the wavelength (frequency) and the amplitude (height of wave) is volume.  Visualize tha sound as a wave... You only hear anything at the highpoints and there essentially silence at the low points.  You don't perceive the silent moments because middle A is 440 cycles/second, just like you don't see the individual frames when you watch a cartoon. 

If I take wave and bounce it off something which is an even mutiple of it's wavelength (makes the wave come back directly on top of itself) you get resonance.  The amplitude of the wave doubles so you hear it at twice the volume, but remember the periods of silence are identical in each direction, but you only perceive the increased volume.  Another wave bounced off a target which is not an even multiple of the wavelength does not superimpose upon itself does not double in amplitude (or resonate) but it has less silent time (half as much) but this is not perceived by the ear, just quieter.

In this simplistic example, both waves can carry the same amount of energy, one is just perceived as louder but with non perceivable longer periods of silence.

This is what the body of an accoustic guitar does for the exact same strings. The sound bounces around inside the body to resonate but if you could perceive it, there are longer periods of silence, no additional energy is created.  The sound is just organized differently.  And this effect does 'suck' the vibration out of the strings and into the body of the guitar making the string stop vibration much quicker.

Does this help?

it "sucks" it out... LOL
how do you plug in an acoustic guitar? if you plug it in, it is not acoustic anymore, but electric...
to make a direct comparision of what? apples to oranges?

All of my accoustic guitars have pickups in the bridge and mics in the body. For plugging into a pa system.  The reason for comparing both amplified is because you simply can't hear how long the electric guitar string vibrates without amplification.  Figured I'd make an even comparison of sustain. The 'sucking' effect is because the body of an accoustic will rapidly absorb the sound(vibration) of the string.  It's not a hard experiment to replicate.

so you are suggesting an amplified hollow body resonator to amplified solid body resonator comparision is apples to apples? and you are comparing sustain by how long you can hear with your ear?

The proper way to experimentally test this is to amplify both instruments, but monitor (if desired) via headphones.

Then set a VU meter (monitoring the input level on a mixer for eg.) such that an open-stringed strum hits 0dB peak and time how long it takes the VU level to decay down to -60dBu or -40dBu or so. Compare the two times.

You will most likely see that the electric solid-body guitar sustain is much longer than the acoustic's.

.99

that is not a proper test. how does turning an acoustic guitar into an electric one make for an apples to apples comparision? by amping an acoustic it becomes electric and therefore no longer acoustic... this is obvious. furthermore, you need a picking method that inputs a precise and repeatable amount of energy, as well as a listening method that involves more than a VU meter and your eyes or headphones and your ears.

spondini,

That may not be a valid test if the distortion was placed before the mixer input.

Both should be clean with no compression or any processing at all.

Also, monitoring over speakers will still impart some feedback (adding sustain) to the acoustic, so it's best to use headphones. In fact, monitoring the audio is not even necessary for this test, because we are relying on the VU meter to indicate the sustain to -60dB. We simply time this and compare.

.99

DrunkCaptain,

You're obviously out of your element here, and because of your brazen attitude towards folks, I'm not even sure why I read and am responding to your post, but alas, I'll answer your questions in good faith.

This particular test as I understand by the last few posts, is to determine which guitar has the longest sustain, the acoustic, or the solid-body electric. Are we in agreement?

Now, amplifying the acoustic's piezo pickup or mic signal does not alter the guitar's ability to sustain it's sound, provided an acoustic feedback loop is not present, and we eliminate this by either not acoustically monitoring at all, or by doing so only over headphones.

The same goes for the solid-body electric guitar.

So we are using a visual instrument that measures "volume units" to indicate when the level has dropped from 0dB down to some chosen level such as -60dBu (almost dead quiet).

A precise picking method would be ideal, but with a few practice tries, for an experienced guitarist it would not be difficult to consistently achieve a 0dB peak strum for each test. However, as a way to increase the likely-hood of accurate readings, 3 or 4 strums/timings could be tried then averaged out to minimize this error.

The precision will only be a factor if after a few tests it is obvious that the two guitars have a very close sustain time to -60dB. Chances are however the two will be quite different, and if demonstrated consistently as such, the small error in strum energy differences can be ignored.

.99

it is 'wilby', that is future tense. it is not 'is' nor 'was'...

to suggest you know what my 'element' is is asinine. because of your presumptuous attitude you are the only expert in your little mind. it's not as complicated as it may seem, and from your proposed test it would seem science is not your element.

yes.

amping an acoustic makes it electric, i assume you will agree with that? i hope this isn't similar to our previous discussion where it took you several posts to agree that a sim is incomplete...
if sustain is sustain then why amp the acoustic? simply put, you are not comparing apples to apples regardless of whatever semantic game you wish to play again. find a more precise method or accept the fact that your proposed test is sloppy. as proposed, your test would be fitting for the mythbusters, but far from precise science.

same goes for the solid body electric.

i am aware what a VU meter is captain obvious. how are you timing it? with a hand held stopwatch?
in your apples to oranges 'test' are you using identical pickups on both guitars? or are you suggesting that all pickups are the same

a precise picking method is required. no ifs ands or buts.

you seem to like to ignore what doesn't agree with your opinion quite often...

Pointy,
   Will rerun test with both through di box, no power to speaker, just using visual meter.

Wilby,
      Blah blah blah.  Makes about as much sense as your posts.

which word did you have trouble understanding?