I recently purchased a nice pair of L-300s from an owner of the last 22 years; they are in nice shape. I promptly sent the 136 woofs off to Orange County Speaker Repair for new surrounds and a regauss.

Now that I have the system put back together, for some reason they just don’t sound as good as I remember them sounding when I was a retail JBL sales person in the 70’s. The bass is every bit as good, but the mids and highs seem a bit veiled, and not open sounding. The HF extension seems okay, and you can tell they are capable of great dynamic range. As it stands now, they do not sound as good as my 4425’s, and I know they should/could sound even better. What to do? I can think of at least 3 solutions.

1. Replace the caps in the crossover. From the threads, it sounds like polystyrene is the way to go. I dropped some Solen polypropylene into my Altec n-800 crossovers and it really brightened things up on my Valencias, too bright actually. What voltage rating on the caps should I get? They’re not listed on the attached schematic. Any recommendations on brands?

2. Replace the diaphragms in the 077 and LE85 and regauss? Ouch! $225 each for JBL ‘phrams ($75 for Radians), plus $25 X 4 for re-gauss. Is all this really necessary? There is no aural indication of a ruptured diaphram.

3. Bi-amp? I did this with great success on my Altecs. Turned out much better than my recapped N-800 crossovers. I have a 2 way dbx unit laying around; I could cross at 800hz, drive the 136 directly and the 077 and LE85 via the crossover. From the looks of the 3133A schematic, the switch merely takes the woofer out of the circuit. Is that correct?

4. I could also take the crossover out entirely, biamp at 800 hz, and use a cap on the 077 at a strategic point. But where? Would the LE85 roll off gracefully?

So what is the best solution? I’d really prefer to upgrade the crossovers and call it good if that will produce good results. I don’t understand this "Bypass Caps" deal, but will read the thread one more time.

Comments would be greatly appreciated.

Bryan

L300 schematic below