Thanks again guys!

The reason I'm chasing the Power sensitivity rather than the voltage sensitivity is that I want to model the drivers using WinISD and it likes the former measure

RonE, I'm almost there; at the risk of incurring mathematics burnout, let me follow your equations longhand:

for Power sensitivity:

dB=112.2+10*log(9.614e-10*fs^3*Vas/Qes)

For both series and parallel conections Qes is half that of a single coil connection (or so I have been led to believe)

so the equation becomes:

dB=112.2+10*log((9.614e-10*fs^3*Vas/Qes)*2)

which simplies to:

dB=112.2+10*log((9.614e-10*fs^3*Vas/Qes)*2)+ 10*log(2)

thence to

dB=value for single coil connection + 3 dB

------------------------------------------

as a check, do the conversion to 2.83v spec using a pair of 4ohm coils

add 10*log(8/Re) to the Power sensitivity figures

series case (total Re 8ohms)

-----------

dB = (value for single coil connection + 3 dB ) + 10*log(8/Re)

dB = (value for single coil connection + 3 dB ) + 10*log(8/8)

dB = value for single coil connection + 3 dB

Parallel case (total Re 2ohms)

-------------

dB = (value for single coil connection + 3 dB ) + 10*log(8/Re)

dB = (value for single coil connection + 3 dB ) + 10*log(8/2)

dB = (value for single coil connection + 3 dB ) + 6

dB = value for single coil connection + 9 dB

To summarise

------------

"Power" sensitivity SPL

[email protected]
series sensitivity = single coil sensitivity + 3dB

parallel sensitivity = single coil sensitivity + 3dB

Voltage sensitivity

[email protected]@1m

series sensitivity = single coil sensitivity + 3dB

parallel sensitivity = single coil sensitivity + 9dB

which contradicts your earlier figures for voltage sensitivity of

series equal to single and

parallel 6dB more than single

I seem to have picked up 3dB too much somewhere. Is it related to the "half space"?

although my head is spinning, I do appreciate the help!

regards, Collo