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ATHENA TECH 1" TEXTILE DOME SHEILDED 4 OHM TWEETER
This tweeter looks pretty
nice.
Keep in mind that the input is equivalent to 1/2 watt at 1/4 meter
(which
will measure at virtually the same level as two watts at 1 meter) due
to
the
4 ohm impedance. So, burn off 3 dB if you want to know what is
happening
at one watt @ one meter (into the 4 ohm load.)
I find that an average of the on axis and 30off axis curves usually
corresponds
pretty well to what I hear, and, in this case, that would be good.
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Note that duals I run with the coils in series. For
operation in parallel,* the inductance and resistance are divided by 4 -- the
latter will make voltage sensitivity go up by 6 dB, but actual efficiency is the
same.
*That will mirror dual coil operation off 2 channels of a stereo amp -- you
just have to figure the signal (power) from both channels if looking at what
the speaker will do at any particular power level. (You probably already
know all this, but I run into a lot of questions about dual coil performance
and the data as taken with the coils in series or in parallel.)
Other notes:
The woofer was broken in 10 hours, then allowed to rest a little over 10 hours
for the suspension to recover / stabilize.
Operation starts getting noisy around X = 0.75", so you could probably
figure Xmech (maximum useable excursion) as being about 10 mm peak.
This models nicely in a 0.75 cubic ft. ported enclosure tuned to 45 Hz --
just a little off an ideal 4th order Butterworth system, with response -3dB
at 46 Hz, maybe a 1/2 dB bump centered around 70 Hz. Going to 1 cu. ft.
with eq. would get you down under 40 Hz, but without eq. it would have a
little mid-bass suck-out due to overdamping. Going smaller (0.5 cu. ft. and 46 Hz tuning)
it's still ok, but the port gets a little out of hand -- ok with a passive radiator,
though. There is no good sealed box configuration -- too much motor for
that to work out and have any bass at all. (This thing looks like it was
designed -- fairly well -- for ported box all the way.)
Shielding is not the absolute best I have ever seen, but, it is pretty darn good.
I'd say somebody knew what they were doing, and better shielding probably
would have driven up the cost significantly.
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