Originally posted by Hilmar-at-Bose:
"... most instruments have comparatively little energy at the "fundamental" or nominal frequency. In fact very low frequencies don't contribute to "punch" or the perception of powerful bass, but they tend to add an indistinct rumble. That's the reason why most (famous) bass cabinets go only down to about 55Hz or so.
I haven't heard (or measured) the poarchboard yet, but I would assume that it has also considerable energy at higher harmonics and apparently is sounds good as it is"
I am very interested in this statement Hilmar. The bit about the fundamental frequency having comparativiely little energy. I am trying to understand how an acoustic guitar gives a much more pleasing sound than a solid body instrument. Surely the hollow body does much more than just amplify the strings' vibration, the energy flow is not just one way. We have a dialogue going on here, the string makes a statement to which the wooden body responds and feeds back a subtle reverberant answer coloured with its' own personality. Listen to the sound of a double bass being plucked, the initial impulse creates a tone that aquires colour and warmth as it decays, the resonance of that beautifully designed wooden body transmits counter vibrations back into the string which modify its movements, adding overtones and muting some others. That is a poetic kind of description, I'm sure you could give me a more scientific one which I would appreciate if you have the time.
I wonder if anyone has studied this interaction between string and resonator. I have toyed with designs for a solid body instrument with a bridge which is not solid metal but a spring-steel comb arrangement designed for maximum resonant response, I am forever dissatisfied with the solid body tones, the waveform if I could see it I'm sure would contain a very prominant fundamental frequency which when amplified electronically gives out a tone which is painfully lacking in colouration for my taste. Why else would we need all these effect pedal gysmos?
Here is an idea for an insrtument amplifier, I'm sure Bose would do a great job of producing it. Companies like Korg and Line 6 put a lot of research into analysing the colouration added by various classic guitar amplifiers and simulating the tones with a digital effects unit. All well and good but why not design an amplifier that sets out to colour the sound by constructing it with resonant tone woods just like an acoustic guitar body. Why not have the speaker direct its vibrations into an array of metal springs or other responsive materials, even tuned strings? then sense the reverberant overtones and feed them back into the amplifier so that the original guitar tone is modulated by these secondary sounds. Isn't this the basis of FM synthesis?
I feel sure that when more attention is given to the quality of the source tone the desire for extreme loudness becomes less. Natural acoustic tone has some very subtle qualities I think. It is such a shame to have to endure live music which is so loud that it causes physical pain. We feel the sound but the ears simply cannot discern subtlety because the delicate inner mechanism is locked up in self defense. I forget who told me this, a medical student who was studying hearing loss I think, explained to me the mechanism the human ear uses to protect itself from damage. By locking its delcate moving parts loud noise can be endured for a while. but if exposure is prolonged the ear sustains irreversible physical damage and the range and quality of hearing is impared.
You can verify this for yourself at the next loud concert, press fingers firmly into the ears, you will notice that the pitch of the sound apparently drops about a quarter tone and although treble frequencies are muted, magically what seemed like a turbulent whirlpool of muddy sound becomes clearer. without earplugs the sound is confusing, but with the attenuation the stereo image is restored and some of the subtleties of musical expression become discernable.
It may seem an irony to say this in a forum concerned with amplification but I believe that our ability to hear a sound as beautiful depends more on how carefully we are listening than on how pure the sound source is. How on earth did performers manage to get the attention of an audience before amplification was available? There are ways of bolstering the power of the human voice, many singing in unison, a soloist must train to master voice projection by using the breath economically for maximum volume with minimum expenditure of energy. The clever ones also used charm to draw the attention of the listener to a very receptive level of awareness.
The introcucion of electronic amplification has given us power which anyone can easily use. But power must be used wisely or it will intoxicate the unwary user. The same laws of nature still apply, brute force unguided by sensitivity is an ugly thing.