High Efficiency Speaker Asylum

Posted by Paul Joppa (P) on February 12, 2007 at 21:17:55

In Reply to: Re: Looking for some JBL help/suggestions posted by noroom4squares on February 12, 2007 at 13:16:46:

The whole thing is fairly arcane, so you're going to have to do some studying I'm afraid.

I assume when you say you have the "throat and lens" you are referring to the very short horn, about 4" long, throat 2" diameter, mouth 4" diameter. It was used with a slant-plate lens about 10" wide. This is pretty classic, and was often used with the 075 "bullet" tweeter and the N8000 crossover. I think you have the makings of a really classic vintage system and it would be a pity to muck with it.

Note that this is old enough that the "16 ohm" speakers may actually be 8 ohms. Check the voice coil DC resistances to be sure. The N500 crossover may also be labelled 16 ohms but otherwise identical to the later 8 ohm version. Like I said, all this can get pretty arcane.

The woofers are something special, one of very very few underhung designs with reasonable excursion. There were quite a variety of surrounds at various times (one oddball "plastic" that hardened up as it aged, and supposedly can be rescued with automotive brake fluid ...) so a little research may be needed to make sure it's in good shape.

The 375, if it has the original diaphragm, will go up to 8 or 10kHz. But many later diaphragms will fit (not all, of course - arcane, remember?). The aluminum ones are said to sound better, but they are subject to fatigue cracks if over-stressed.