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Re: USB sound cards
Dick, the loss you are looking for is in the resistive component of the
transducer impedance. For example, in a moving coil loudspeaker this
might be on the order of .5 to .8 x the nominal impedance.
In order to provide maximum damping from the source amplifier, zero
output impedance is a step in the right direction but negative output
impedance can considerably improve on that (with the risk of instability
if taken too far).
From long ago memory one UK Hi-Fi amplifier back in tube days had a
variable damping control which enabled output impedance to be varied from
plus several ohms to minus several ohms (was that amplifier the Pye
'Mozart'?).
NeilA
At 01:30 PM 12/16/2014, Richard F. Lyon wrote:
On Sun, Dec 14, 2014 at 6:15 AM,
Bob Masta
<audio@xxxxxxxxxxx>
wrote:
- However, if instead of disconnection the leads were
- *shorted* after the pulse, the generator would be driving
- all its current into the zero-ohm load, giving a maximum
- damping effect.
I'm not buying that. A zero-ohm load is lossless, just like an
open circuit. Damping requires loss. Whether higher or
lower resistance makes more damping depends on the nature of the
resonance.
Dick
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