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Niklas Nord
12-12-2004, 04:38 AM
Hi

Now we have measured the distorsion on the JBL SUB1500 driver.
It turned out to be low, and thatīs great offcouse. I got help
from a friend here in Sweden, he has the right tools to do this
kind of measurements..

Some notes about the measurements that you should read before
looking at the diagrams below.

"The driver was measured in free air with the microphone in the extreme near field and the capsule almost touching the membrane. The recorded SPL was then recalculated to approximate hemispherical (2 pi) radiation at 1 meter through numerical integration, including diffraction effects. Rigid piston behaviour from the membrane is assumed, which is an oversimplification for higher frequencies. The microphone used was of laboratory grade (type 0) and capable of handling very high SPL:s (< 3 % THD @ 146 dB). The results produced by this method should only be considered approximate, but differences compared to more conventional methods should generally be small."


http://www.pal.pp.se/~nord/projektaurora/distorsion_jblsub1500/sub1500fg.gif

http://www.pal.pp.se/~nord/projektaurora/distorsion_jblsub1500/sub1500dist.gif


If you know how to read this kind of measurements, you can see that
distorsion is very low. We dod an comparison with the Adire Tumilt and Adire maelstrom, and they was booth beaten by SUB1500. The maelstrom seems to be nice, not far away, but the tumult was far from this good. JBL knows their physics well :)

We stopped the test @ the highest SPL couse I could not stand the sound :D Thatīs why it stops just after 100hz.

The third tone distorsion is the only thing that sticks out, it would be nice
to run this sub in push/pull -configuration, though the distorsion is so low,
that would be some overkill maybe.

BUT WE LIKE OVERKILL HERE :D


I hope you all, liked this posting !!

Best regards
Niklas

4313B
12-12-2004, 06:08 AM
"It turned out to be low"

Third party confirmation is often a good thing. :)

Niklas Nord
12-12-2004, 08:16 AM
Yes, and we should all be very very happy, having those
drivers at such a low price.. !!!!

They are really something spectacular !!