Yes, the acoustical impedance match will determine how good it works. A direct analog of tuning out a mismatch in a transmission line for maximum power transfer at ONE frequency. Well sort of, their optical analogy is better since it is a plane wave on a surface, I'll bet getting it to work at lower frequencies is problematic.
Last edited:
Just ran into this: The magic of negative feedback | EDN
Of course, Sergio Franco is well known in the analog world.
The article discovers nothing really new, but gives a nice alternative insight and shows some nice class B xover waveforms.
Jan
Of course, Sergio Franco is well known in the analog world.
The article discovers nothing really new, but gives a nice alternative insight and shows some nice class B xover waveforms.
Jan
It is not per se a resonator. Think more of a horn compressing the sound to fit in a small hole and another on the other side allowing it to expand again. increase the horn coverage angle until it is very wide. (Or even flat.)
Given an input wave of sin(w) +/- jsin(w), the plastic sheets will have a given thickness and mass allowing a resonance hopefully of the same (w). The j component will multiply along with the original sin(w) and add to zero with two coupled sheets.
I have tried to explain issues like this before and folks usually don't understand my approach but then re-express it in a math form they find comfortable.
ES
They do say the membranes are tuned to resonate at the incident frequency, a stretched membrane is a resonator by itself, the coupling to the air to get the desired effect is the issue.
I think the issue is; does the air in a pinhole act as a rigid or elastic media? If you have two matching membranes on each side, the issue is the coupling mechanism.
If the air in the pinholes acts as a rigid but movable mass, the coupling seems clear. Now if the air gets compressed and rarefacted then the issue of transfer efficiency enters. Now as is I presume well known is PV=NRT. So what in that equation is non-constant and what is the modulation function? What is the realstionship between velocity and acceleration?
If the air in the pinholes acts as a rigid but movable mass, the coupling seems clear. Now if the air gets compressed and rarefacted then the issue of transfer efficiency enters. Now as is I presume well known is PV=NRT. So what in that equation is non-constant and what is the modulation function? What is the realstionship between velocity and acceleration?
I think the issue is; does the air in a pinhole act as a rigid or elastic media? If you have two matching membranes on each side, the issue is the coupling mechanism.
If the air in the pinholes acts as a rigid but movable mass, the coupling seems clear. Now if the air gets compressed and rarefacted then the issue of transfer efficiency enters. Now as is I presume well known is PV=NRT. So what in that equation is non-constant and what is the modulation function? What is the realstionship between velocity and acceleration?
You're overthinking the problem.
They setup a resonance. The resonance creates much higher pressures, as energy is stored in the resonant mechanism. That gets it through.
It's a single frequency mechanism. Look up quarter wave transformers. That's the idea, but this is a mechanical analogue.
jn
Scott, The membrane is the only element I see resonating. What is the efficiency of a membrane resonator (drums and the like)? Does it compare to the figures in the article?
Ed, me too need a link for the j component adding to zero with the two coupled sheets (and it’s not clear that they used two sheets)
Interesting line of thinking but we will be led astray. There is no mass transfer through the membrane, only energy transfer .Now as is I presume well known is PV=NRT. So what in that equation is non-constant and what is the modulation function? What is the realstionship between velocity and acceleration?
I would visualise the case as an array of ferroresonant transformers. Energy-in, energy-out, some losses but no current flow from in to out. I guess also: Zin=Zout
Please have a look here.
“Extraordinary optical transmission through sub-wavelength hole arrays”:
http://arep.med.harvard.edu/pdf/Ebbsen98.pdf
I am puzzled as to why the did not replicate the measurements and diagrams for the case of non-metalized diaphragms. This way they would have a clear picture as to what geometry contributes and what the assumed plasmon-photon interaction contributes to the extraordinary results, independently and quantatively .
They only make a remark:
George
These units are the very conventional Dell plastic satellites, designed by Brad (bcarso). They perform admirably well, all things considered, they are what I use for distinguishing the different music track versions - and they make the exercise quite straighforward, their 'clarity' is perfectly adequate. Their weakness is the bottom of their range - sharp cutoff at 100Hz - for the left speaker, almost at the limit of audibility of sound the harmonic distortion is very apparent, whereas the right unit can go up to about 1/3 volume before the harmonics start to intrude to the same degree - all obviously well before the amplifiers start to overload. At close to maximum volume, when feeding pure 100Hz tone, an electronic type buzzing kicks in, this is where the electronics are clearly no longer functioning normally.
I've done various sweep and other tests to check various behaviours, but nothing systematic so far. But, looking to organise something in the next couple of months, to be able to do far more precise recording of what the speakers are producing.
Acoustics is a nightmare, at best. When you combine it with mechanical systems, it gets far far worse. thiele-small is a lumped parameter approximation, that was seemingly formulated with with a blindfolded dart shot, on a wing and a prayer. It falls apart at almost every stage, all it can do is keep the wheels between some imaginary guardrails (that reality constantly breaks through)(like a car going off a cliff).
We are a giant ball of learned, blinkered and polarized editorializing systems, in touch, eyesight and hearing. All of it is based on instinct, how we were raised (emotional learning and casting) and our given fundamental genetic gifts or weaknesses.
A recent study (IIRC found at physorg) illustrated that we do indeed see 'all', but we filter. We filter based on the above conditions, which are unique to us, as an individual.
No-one hears, sees (visualizes), or feels (touch) the same way. All we have is shared generalizations.
Moving past the systems of editorialization, requires a fundamental shift in the base psychology of the self, and the elastic brain can then work on the physiology. To start, it is at the least, emotionally/instictually painful (chemical neural breakage), as old castles of the mind need be shorn and removed, so the new can move in (euphoria, chemical creation of new neural paths). (the old sages were exactly correct)
Only then, can one say there is potential to have experienced something new.
Last edited:
David is back, and he names names.
David Hudson | ORMUS Conference Enota 2011 [FULL VIDEO] - YouTube
- Status
- Not open for further replies.