From: Boris Mohar
Subject: Re: Cancel speaker resistance?
X-Newsreader: Forte Agent 1.92/32.572
Date: Sun, 15 Sep 2002 20:58:26 -0400
NNTP-Posting-Date: Sun, 15 Sep 2002 20:58:28 EDT
Organization: Bell Sympatico
On Mon, 16 Sep 2002 00:17:52 GMT, DPierce@TheWorld.com (Richard D Pierce)
>In article ,
>Kevin McMurtrie wrote:
>>Is there any advantage in using current to voltage positive feedback to
>>cancel the coil resistance of a single speaker driver? Would
>>eliminating the 5-something Ohms improve the sound or is it
>>insignificant compared to other factors?
>One can easily construct an amplifier that has a net negative
>output impedance, thus resulting in a net reduction in the
>total loop resistance of the amplifier/speaker circuit.
>Would it IMPROVE the sound? Yes, it would, if the electrical Q
>of the driver was too high, resulting in a total Q that was too
>high. If the electrical and total Q are what they are supposed
>to be, reducing the total loop resistance would result ina
>driver that is too OVERdamped and the resulting system would be
>less than optimum.
>More generally, if a speaker is competently designed to begin
>with, eliminating the DC resistance of the voice coil would NOT
>be a good thing. As a corellary, if you ARE going to go through
>the effort of reduing the effective resistance with something
>like a negative output impedance amplifier, it would most likely
>be for a specific design, i.e., a specific driver used with a
>Why would one want to do that? Well, getting the Q low enough in
>a driver can be expensive, because it means, generally, a bigger
>magnet, and the magnet is the most expensive component in a
>driver, for the most part. Now, if you were designing an
>integrated speaker/amplifier, and were constrained by budget or
>size, then such a scheme might make sense.
How would one separate the dc resistance of the coil from the from the
resistive total component of the speaker impedance. The total resistive
component being the dc resistance of the speaker in parallel with the
resistances due to the actual acoustic power radiated by the speaker?
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