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reVintage
05-05-2011, 12:51 AM
Anyone who have tried or measured the JBL2407H/BMS4540ND without horn? The driver actually has a short horn integrated with the phaseplug. The intention is to find out if it will work as a supertweeter from 12kHz and up.

pos
05-05-2011, 02:51 AM
I have measurements at home, with and without the small 6" PT waveguide, in 11 increments. I will post them tonight (GMT+1...).
As a supertweeter it is less efficient than a 2405 (more than 6dB less efficient around 10kHz if I remember correctly), but goes higher (the 2405 falls like a rock before 20khz)

reVintage
05-05-2011, 08:35 AM
Great Pos, looking forward to your measurements. A little confused though, as I thought 2407 should have the higher sensitivity.

John W
05-05-2011, 10:49 AM
I haven't had much luck with the 2407H as a supertweeter.

Attached is a curve measured with mine on a shallow oblate spheroid horn. This is measured straight forward.
The sensitivity isn't calibrated, just for reference... Not too great.

Currently they are just plugging the holes. The larger horns in the background are using 2450SL drivers which extend nicely past 15khz, which is fine for my use.

pos
05-05-2011, 01:31 PM
Here are my measurements of the 2407 used as a supertweeter (filtred and EQued), in ~11.25 increments.

with the PT 6" horn found in the AC16 (90x90)
51257

without horn and unbaffled
51258

reVintage
05-05-2011, 02:09 PM
Hey Pos,
Thanks a lot, just what I needed! Did you save any sensitivity-figures w/o horns?

pos
05-05-2011, 02:53 PM
you're welcome!

These two measurements are made with the same power and distance.

Regarding the 2407 on PT vs 2405 comparison I have no clean measurement to show, but from the data I have it seems that their sensitivity is similar around 8khz, then the 2407 drops (but it is predictable and easy to eq) and is around 10dB less sensitive by 15khz. Above 15khz the 2405 starts to fall rapidly whereas the 2407 stays constant so they meet again around 20khz...

Robh3606
05-05-2011, 05:28 PM
The problem you will have with them is the directivity up top will collapse just like a 1" dome. You really need a driver with a smaller throat if you don't want them to beam above 20K. Would be nice to see a driver available with a smaller throat and a horn to match.

Rob:)