I have measured Fs over a range of constant currents (1mA to 50mA). Driver is an 18" with thick, half-roll rubber surround.

Fs trends with current, low current, higher Fs (22Hz), high current lower Fs (18Hz).

Is DUMAX the only correct way to measure Qs and Vas?

"Audio" wrote in message
news:BYjod.445157$D%.259580@attbi_s51...
I have measured Fs over a range of constant currents (1mA to 50mA). Driver
is an 18" with thick, half-roll rubber surround.

Fs trends with current, low current, higher Fs (22Hz), high current lower
Fs (18Hz).

Is DUMAX the only correct way to measure Qs and Vas?

No. But it is one of several possible ways to do so.

"Arny Krueger" wrote in message
...

No. But it is one of several possible ways to do so.



I understand how to measure the impedance modulus. The only way I see to do
it using a constant current method is to measure Fs as a function of drive
current until the drive level is sufficiently high such that the suspension
effects are secondary, i.e. Fs doesn't change as a function of drive
current. Then, a that level, the necesary measurements be taken to
determine Qms, Qes and so on. My bench amp doesn't have the "stones" to
take this driver to the levels it needs to go for accurate readings (20W
tube amp).

I was interested in hearing if others have measured this sort of thing. I
suspect that drivers with thick, rubber surrounds would be prone to these
observed "stiction" effects.