Motional and inductance mpedance correction of loudspeaker

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#61
Kindhornman said:
I am interested in the inverse conjugate circuit design correcting the impedance rise and also the minimization of the back emf output of the voice-coil. How I understand this from my long conversations about this with my friend this circuit should be intimately mounted as close to the terminals as possible, no cabling between it and the driver.
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Technically, this close mounting is a good procedure but in reality it may not be necessary. If there was a run of cable between them and it displayed measureable resistance this would be relatively insignificant to the damping of the conjugate. Both the driver and the conjugate (both peak and inductive rise) have a similar resistance which is large compared to the cable.

This may sound dismissive but if it's the loop area you're thinking about then I'd also be thinking of twisting the speaker cable, even shielding it. An amp should be compensated for this anyway, and will normally have series inductance and shunt damping for HF(RF).
 
#62
Esperado said:
Hi, Andrej. Thanks for you input. I agree on most of it.
On point 1, i don't fully agree. First, The serial resistance of the serial coil are high, compared to the amplifier one. second, considering the high impedance of the load at the two picks of impedance around the resonance in bass reflex, there is nothing witch can explain this ~2db of change in levels due to the Motional impedance compensation where we don't see the two peaks and the resonator's charge.
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The serial resistance of the coil is a red herring here. The bass alignment of the driver/ box can be designed assuming certain values for the source impedance, ie the amplifier, cable and coil resistance. It's just a matter of choosing the correct Bl/Re factor for the driver. Also, if you are driving from a typical tube amp, then the coil resistance is insignificant compared to the amplifier source resistance. Too much is made of damping factor. All it does is very slightly alter the Qe of the system, but since this is dictated by the total series resistance, including the voice coil, then the change due to the series inductor can be kept very small.
 
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