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A Question That Has Burned In My Mind For Years...
- Thread starter laatsch55
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Dayam Lee...
The sound of multiple instruments and voices superimpose themselves in the air to produce a live sound. That superimposed set of sounds produces a complex waveform in the air pressure representing all of them simultaneously. The microphone picks this complex air pressure waveform and transforms it from a mechanical to electrical complex waveform which is then stored in various media forms. Upon playback, the amplifiers reproduce that complex waveform and send it to your woofer, mid and tweeter which reverse what the microphone did. Converting electrical to mechanical air pressure for you to hear.
The human body and ear are much more complex than that, so don't go there...
The sound of multiple instruments and voices superimpose themselves in the air to produce a live sound. That superimposed set of sounds produces a complex waveform in the air pressure representing all of them simultaneously. The microphone picks this complex air pressure waveform and transforms it from a mechanical to electrical complex waveform which is then stored in various media forms. Upon playback, the amplifiers reproduce that complex waveform and send it to your woofer, mid and tweeter which reverse what the microphone did. Converting electrical to mechanical air pressure for you to hear.
The human body and ear are much more complex than that, so don't go there...
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Celestion (and apparently Wharfedale too) used High Speed Laser Interferometry to create 3D "topographical maps" of driver surfaces in operation.
In 1982 Celestion launched an innovative hi‑fi speaker called the SL6. It deployed one of the first 'modern' metal-dome tweeters — one that employed copper pressed (literally) into service as both diaphragm and voice-coil former — and a thermoplastic-coned bass/mid driver with an unusual dust cap and surround design. Both drivers had been developed using laser interferometry. Laser interferometry employs a laser to scan across a moving surface, with analysis of the Doppler effect changes in frequency of the reflected light used to derive the detail of the movement. Using laser interferometry, Celestion could create slow-motion 3D animations of the movement of driver diaphragms and so optimise their mechanical design. It was a brilliant application of technology and Celestion's marketing department understandably made a big fuss about it. However, it wasn't entirely new: Peter Fryer at Wharfedale in 1971 had used the same technique to help inform the design of a new thermoplastic‑coned mid-range driver.
In 1982 Celestion launched an innovative hi‑fi speaker called the SL6. It deployed one of the first 'modern' metal-dome tweeters — one that employed copper pressed (literally) into service as both diaphragm and voice-coil former — and a thermoplastic-coned bass/mid driver with an unusual dust cap and surround design. Both drivers had been developed using laser interferometry. Laser interferometry employs a laser to scan across a moving surface, with analysis of the Doppler effect changes in frequency of the reflected light used to derive the detail of the movement. Using laser interferometry, Celestion could create slow-motion 3D animations of the movement of driver diaphragms and so optimise their mechanical design. It was a brilliant application of technology and Celestion's marketing department understandably made a big fuss about it. However, it wasn't entirely new: Peter Fryer at Wharfedale in 1971 had used the same technique to help inform the design of a new thermoplastic‑coned mid-range driver.
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Possibly a simpler way to look at this would be octaves or evenly divisible frequencies? I often wondered how this worked electrically and that mystified me more than the physical woofer reproducing that signal... play a song that’s in a minor key or with heavy dissonance, I think these are the hardest for a speaker to physically reproduce and some fall on their face...
Always amazed me too Lee as well that a driver could do all that simultaneously. The ear part, nah, our best engineer on that one so I never wondered there. But the little cone doing all those frequencies and responses so accurately, made out of paper, all at the same time is a tough one it would seem. That Celestion scan showing what parts move in relation to the input would be interesting thing to see, might help wrap our minds around it better. The voice coil must do all within the required freq range, for sure, the cone, might see some differences in relation to distance from the VC, esp on the bigger cones.
And dual voice coils in same driver, one responsible for different frequencies than the other, more wizardry. Joe's explanation was like the sex explanation to a young child,, missing some important details I think! Maybe he is protecting our fragile minds.......
And dual voice coils in same driver, one responsible for different frequencies than the other, more wizardry. Joe's explanation was like the sex explanation to a young child,, missing some important details I think! Maybe he is protecting our fragile minds.......
If you had a driver with zero mass and no reactance (inductance or capacitance) in the voice coil, you would eliminate the mechanical time constant and electrical time constant associated with real world woofers and tweeters. If those zero time constant drivers were operated in a perfect vacuum, you would approach an ideal driver situation. Unfortunately they have to move air to be effective and let you hear anything 
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Okay, dogs- looks like I have to git my crayons 'n' draw pictures for ya's...
Top wave: 60Hz sine wave
Middle wave: 45Hz sine wave
Bottom wave: Both sine waves combined, now is no longer a sine wave, but a simplified "complex" wave.
Neither of those frequencies are compromised but interact with each other, a vertical line drawn from either the 60Hz or 45Hz wave will show a corresponding peak on the combined wave. Simplified to its most elemental form, but this is how vocal waves combine with guitar waves with violin waves with (ad nauseum...).
Further thought: consider how audio frequencies are modulated with radio carrier waves...
Top wave: 60Hz sine wave
Middle wave: 45Hz sine wave
Bottom wave: Both sine waves combined, now is no longer a sine wave, but a simplified "complex" wave.
Neither of those frequencies are compromised but interact with each other, a vertical line drawn from either the 60Hz or 45Hz wave will show a corresponding peak on the combined wave. Simplified to its most elemental form, but this is how vocal waves combine with guitar waves with violin waves with (ad nauseum...).
Further thought: consider how audio frequencies are modulated with radio carrier waves...
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