"dangling entity" wrote in message
om
"Arny Krueger" wrote in message
...
"dangling entity" wrote in message
om

Some
are better at minimizing the effect than others, of course.
Naturally, there are few, if any, loudspeaker manufacturers that
care to expose that sort of information about their product (if
they have even bothered to discern it). I don't believe Clark's
Duomax measurements would necessarily reveal its effects, either,
unless studies are expanded to study (very) large signal inputs,
rather than just standard small signal inputs to determine motor
strength.

The Dumax can fully stroke large woofers such as the JL Audio unit
above, which means that it can and does apply relatively large
currents to the UUTs.

It does so [the cone displacement] by air pressure (applied by another
woofer), no? Hence, there is no requirement to use large input
currents to get a motor reading. More likely, a very small signal is
used to get motor readings at the various displacements so as to give
the most stable results, unperturbed from unnecessary ohmic heating of
the VC. They *could* do high signal tests (with additional
limitations), but this is not a requirement, nor a default step in the
standard test, AFAIK.

Dumax uses two vastly different means, both air pressure and current through
the voice coil, to displace the cone. BTW, the air pressure does not come
from another woofer. It comes from an air pump.

http://www.dlcdesignaudio.com/dumax.htm shows the Dumax machine. The air
pressure source is connected to the test chamber via the black hose running
behind the left vertical test chamber support. The current source is inside
the interface unit which has two meters, and is sitting on the right half of
the table under the test chamber.