JBL L96 Tune-Up

[Zekeman]

I have three sets of L96’s and have determined that I am not getting all the tweet and or midrange, as designed, out of a couple of them. I, therefore, have decided to do sometuning-up/ restoration but am not sure about exactly what to do. First, should I recap part of the networks? If so, what are the recommended components: all or some of the caps?

Secondly, I think a couple of my LE5’s are suspect…what is the best source for recone kits?

Thanks.

[rdgrimes]

LE5-12s are pretty easy to come by, I'd replace them rather than mess with a re-cone. To each his own. You can also use LE5-10 or LE5-8, the only differences being cosmetic. Start by checking them for proper DC ohms across the connectors, (4.9-6.1) and silent easy movement of the voice coil. (they don't move much). You can also feed them a sweep tone and listen for issues like buzzing or an uneven response. recommended sweep tone is 75-3000Hz, but I would use something closer to 500-4000Hz. Feeding the complete system some sweep tones will also reveal any holes in the response curve and other issues.

The L-pads are by far the most common source of issues and should be cleaned and verified to be working well. Rebuilding the XO can't hurt either, but the improvement will be subtle unless one of the caps is really bad.

As often as not, an ear to the driver in question can answer a lot of questions, especially when comparing several speakers.

[Ralph856]

Didn't you also mention that tubes at the back of the mid-drivers can come dislodged?

I am also in a similar boat to the OP in that my L96's don't sound quite correct from the mid upwards (possibly only the mid though). The sound in that area lacks body and sweetness, sounding tonally grey and a smidgeon harsh instead.

Instead of merely recapping my networks, I've gone the whole hog and bought a pair of biased 4313b networks with L-pads from a forum member. If the OP's got 3 pairs of L96's, he might want to try that route with one of them.

[rdgrimes]

Didn't you also mention that tubes at the back of the mid-drivers can come dislodged?

If they do, they should pull the wires off the LE5 as they go and the absence of a mid is pretty obvious. The L96 uses the heavy plastic tube that's not likely to just be loose, but if it were you'd see or feel the mid driver cone flopping with the bass.