Gunbei: Most car stereo woofers have a high Qms, which results in a big impedance peak at resonance. This is what causes the bloated, indistinct bass that you hear from the "boom / tizz" vehicles. Lower impedances aren't a problem for a good amp, but as you mentioned, damping factor is reduced.
As a side note, damping factor is NOT the ability of the amplifier to control or load into the driver so much as it is the ratio of how much potential there is for the reflected EMF from the driver to modulate / distort the output of the amplifier. This is a very commonly misunderstood spec with even EE's, designers and manufacturers not knowing how to interpret it or what it really means.
The higher the damping factor, the less susceptable the amp is to being affected by the reactance of the speaker. The ability of the amp to efficiently transfer power into the driver / speaker system ( including cabling ) is what will determine how much "control" the amp has. Unfortunately, there is no spec for this that i'm aware of.
Take a look at this link pertaining to impedances, reactance, loading characteristics and power transfer in the AA Speaker Asylum archives. Pay special attention to the exchanges between myself and that of Dan Wiggins of Adire Audio and to a lesser extent the few responses between myself and Bobby Palkovic of Merlin. One of these two guys is a LOT smarter / more experienced than the other, but i'll leave that up to you to figure out which one it is after reading the exchanges there. While punching in T/S parameters into a computer program and then interpreting the data can provide a lot of useful information, it does not make one a knowledgable speaker designer. Sean
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As a side note, damping factor is NOT the ability of the amplifier to control or load into the driver so much as it is the ratio of how much potential there is for the reflected EMF from the driver to modulate / distort the output of the amplifier. This is a very commonly misunderstood spec with even EE's, designers and manufacturers not knowing how to interpret it or what it really means.
The higher the damping factor, the less susceptable the amp is to being affected by the reactance of the speaker. The ability of the amp to efficiently transfer power into the driver / speaker system ( including cabling ) is what will determine how much "control" the amp has. Unfortunately, there is no spec for this that i'm aware of.
Take a look at this link pertaining to impedances, reactance, loading characteristics and power transfer in the AA Speaker Asylum archives. Pay special attention to the exchanges between myself and that of Dan Wiggins of Adire Audio and to a lesser extent the few responses between myself and Bobby Palkovic of Merlin. One of these two guys is a LOT smarter / more experienced than the other, but i'll leave that up to you to figure out which one it is after reading the exchanges there. While punching in T/S parameters into a computer program and then interpreting the data can provide a lot of useful information, it does not make one a knowledgable speaker designer. Sean
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