DeserTBoB wrote:

Harvey Gerst wrote:

The JBL 075 (don't know what it's called these days) went out to 40 KHz with
very high efficiency. snip

Not true. 075 = consumer version, 8 ohms 2403 = pro version 16 ohms
-3 dB down at 15 KHz on axis.

Not from what I remember. We use to sell them to the Army (for God knows what
purpose), and to the Highway department (to use as vehicle counters at 25kHz).
There WAS NO off-axis response; at JBL, we called it affectionately "The
Acoustic Laser".

The "slot" was 077 = consumer version, 8 ohms 2405 = pro version 16
ohms -3 dB down at 25 KHz on axis.

That was Ed May's slot-loading modification to Bill Burton's original 075
design. The only difference between the two was the dispersion, IIRC - same
diaphragm and magnet assembly.

40 KHz? It might be there, but way, WAY down in the mud.

I don't think so.

Harvey Gerst
Indian Trail Recording Studio
http://www.ITRstudio.com/