"Arny Krueger" wrote in message
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"Pooh Bear" wrote
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wrote:
"Arny Krueger" wrote in message
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"Pooh Bear"
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So what do you think it is that makes damping factor
*unimportant* ?
It's not that damping factor isn't important, its that
it is an odd way to express the underlying physical
parameter which is amplifier source impedance.
For openers, damping factor isn't an amplifier
parameter, its a parameter that is also strongly
dependent on load impedance. Unfortunately the
underlying physical parameter remains pretty much
unchanged, regardless of load impedance.
With good modern amps, the amplifier's damping factor
is generally so high that it gets swamped by all sorts
of things including voice coil DCR and speaker wire DCR.
It means a lot more with tubed amps.
Which is probably why it was ever expressed as a value
at all. When they came up with it, tubes were dominant,
then came good more accurate, less volatile,
transistors. :-)
Whether tube ( valve ) or transistor - damping factor ( a
reciprocal measure of amplifer output impedance ) is
important.
A low damping factor means that an amplifier cannot
adequately control speaker resonances or the back emf
caused by transients.
This would be a common misconception.
When one designs a speaker system, the source impedance of the amplifier
is simply part of the design of the speaker.
For example, if you *know* that the amp has a source impedance of one ohm,
you simply design for that operational condition. You plug one ohm into
the Thiel/small parameters for the woofer, and you plug one ohm into the
design of the crossovers.
But that's the problem, Arny, you don't know, unless you are
perhaps a broadcast engineer specifying a complete audio chain.
People expect their new amp to work with their existing
speakers, and vice versa. If these speakers present a difficult
load, or do not comply with the recommendations of
IEC/EN/BS EN 60268-5 they may find themselves sadly
disappointed.
SETs can produce the most wonderful small-ensemble music
at lowish levels with full range horns, but try one with an ELS.
Do the designing right, and you end up with a speaker that is no more (or
less) resonant.
Few if any of us design our own speakers.
Iain