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Originally Posted by gsferrari
I am no layman. I am an engineer with quite a bit of experience in these matters.
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(I know!) So it won't be hard for you to justify your scenario:
«You ABSOLUTELY need an amp with a lot of headroom to overcome the extremely high elasticity of the driver.» What is «elasticity»? Compliance? Or rather stiffness? Let's assume it's the latter... It would cause an awfully high resonance frequency coupled with the low moving mass you would expect from a membrane running up to 100 kHz and beyond. But then again: low compliance and high resonance frequency mean high resonance Q factor, thus low mechanical damping. That's not what you wanted, obviously. So let's assume the membrane has a high inner damping. It's possible, but again stands somewhat in the way of the high bandwidth, as high inner damping means slow speed of sound.
The other questionable thing is the requirement of an amp with «a lot of headroom», which I guess stands for power. Now what sort of power is needed to drive the membrane to a travel of 0.05 mm at 500 Hz? Maybe 1 mW. Now, what does it change when the one milliwatt is coming from a muscle amp instead of a smaller one? It's the same power, causing the same displacement. Let's assume a similar output impedance, since that's not a feature of an über amp. So even the electrical damping of the membrane at the resonance frequency will be identical.
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| As far as your idea of damping - I am NOT talking about the chamber or driver housing. I dont think the SA5000 has a bathroom sound either. I am talking about the control over the driver when I say "damping". |
Actually I've realized that, but couldn't resist to throw in the SA5000's most obvious design flaw. Your high (mechanical?) damping theory is mere assumption, right?
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| What this means is that, the driver doesnt FLOP about in response to a signal - it is taut and harder to move. |
No, I'm not buying this scenario -- see above! And BTW a stiff membrane (or suspension) isn't even harder to move than a more compliant one
above the resonance frequency!
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| Extension just isn't there without a more powerful amp. A weak amplifier will be unable to control the movement of the driver. |
You forget that there's no headphone amp with integrated motional feedback, active movement control. Amps just deliver their current, at best around the bass resonance there may happen some back EMF effects -- according to the output impedance (= damping factor) --, but that's not dependent on the amp's power reserve. In any event: 1 mW will cause the same membrane displacement and the same sound pressure from both a weak and a strong amp; and a «high elasticity» doesn't change a bit.
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| There will be a delay between the signal, and the driver responding to that signal in either direction, when the amplifier is not up to the task. |
You're talking Spanish to me... The speed of electricity isn't dependent of the amp's (--> unused!) power reserve.
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| A strong amplifier will be able to move the driver with the speed that is necessary to keep up with the audio signal. |
A weak amplifier with higher bandwidth will drive the driver with even higher speed than the stronger one (given a signal with extreme HF extension!), as long as it's not driven close to or above its power limits. Remember: 1 mW is 1 mW, it's not a stronger milliwatt when it's from the stronger amp. The only concession I'm ready to make is that a stronger power supply may be able to convey more authority and dynamics to the sound -- but that doesn't have anything to do with elasticity and motion control.
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