Film-Tech Forum ARCHIVE: JBL 2447H

This is topic JBL 2447H in forum Film Handlers' Forum at Film-Tech Forum ARCHIVE.

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Posted by Marco Giustini (Member # 4544) on 06-25-2015, 02:58 PM:

Hi there,

I found some old JBL speakers with 2447H compression drivers. I am not familiar with those drivers, I understand the throat exit is smaller than the more common 2446's.
Any opinions on the driver? Is that good for cinema use?

Thanks

Posted by Mark Gulbrandsen (Member # 72) on 06-25-2015, 04:03 PM:

That may be a driver that's used in some of the Studio Monitors....

Mark

Posted by Marco Giustini (Member # 4544) on 06-25-2015, 04:47 PM:

is it? It's still a 38mm throat exit 100mm titanium diaphragm, what kind of 'monitor' are you thinking about?

Posted by Steve Guttag (Member # 268) on 06-25-2015, 08:27 PM:

It is for JBL's "optimized aperture" line of horns. The idea being to reduce the turbulence of a longish throat.

http://www.jblpro.com/pages/components/23525354.htm

I've known people to use them for cinema and those that did said they much preferred them over the likes of the 2380 series (which definitely had its issues near crossover).

Posted by Marco Giustini (Member # 4544) on 06-26-2015, 02:27 PM:

Thanks Steve

Posted by Louis Bornwasser (Member # 3063) on 07-03-2015, 11:21 PM:

Harmonic distortion is reduced below the theoretical with the 2447. Sounds great. Does have a need for a higher (750-800Hz) crossover. Does not work well for long throws. Usually I only used them up to 600 seats.

Posted by Steve Guttag (Member # 268) on 07-04-2015, 08:00 AM:

The horns are rated down to 500Hz and actually do MUCH better than the dreaded 2380 horn...which effectively is omni-directional at 500Hz. For cinema use, 500Hz is the preferred crossover point for 2-ways though your power handling will go down a bit at the lower frequencies so a slight upping to 630Hz but no higher than 750Hz can be used for better power handling.

As to longer throws...there are three horn types to control the pattern though yes, the results of short horns on long throws are never going to be as good as their larger counterparts. It is like going hunting with a pistol versus a shotgun.

Posted by Marco Giustini (Member # 4544) on 07-04-2015, 09:14 AM:

This is very informative, thanks both!