L-300 Bypass Capacitor Experiment

[Regis]

It turned out really well. My belief with bypass caps is that it should be icing on the cake. Here are my thoughts on the result. I noticed better detail, with less blending of the mid and mid-bass on some of the instrumentals. Imaging was improved somewhat. Most noticable on both the L-300 and the L-150 is that they both lost some of the 'boominess' in the bass. The Summit responded especially well, with the bass tightening up really well. I'm happy with the results. Don't expect a huge difference, remember, these are very small values and as I said it's icing on the cake, though the speakers are noticably more pleasing to the ear. I found it hard to believe you could improve on the sound of an L-300, but this works nicely. The caps were of good quality, typical of what I believe JBL would've supplied OEM (the bypass caps I pulled off the L-150's "L-112" crossovers were .068 uf, 20% tolerance caps, nothing super fancy here) so that's the route I took. By the way, even empty JBL L-112 cabs can have some use besides looking ugly with big holes. They make nice stereo equipment tables (saved on an entertainment center).

Again, if you like to play with cap combinations, my hat's off to you (Earl K!). Have fun and I do respect those like Ian McKenzie and Zilch who put together some pretty exotic X-overs. My whole mission here was to show a modification at minimun expense and trouble for L-300, 4333 owners. Thanks for reading.

[Earl K]

Nice Pictorial Regis !

Thanks for the testamonial .

[Earl K]

For those interested in persuing bypass mods like this , here's the link to Mousers' Xicon "MPP" type caps .

And heres the link, to Mousers' Polystyrene caps .

[johnaec]

Nice mods! I'm thinking of doing the same to the crossovers in my 4315's. It's got the same kind of crossover can, and I've already determined, (by comparing the schematics with the crossover), that I can do it like you did, using the point-to-point connections in the top. 'Just have to get around to it...

John

[Regis]

Thanks Earl for the linkee's to Mouser's PDF files, that was a big help. I shoulda thoughta that! For the .01uf metallized polypropylene, I used Xicon (Mouser PN 1429-6103), they're way over-rated at 630 WVDC, but that was the only MPP cap at that value, .01uf didn't exist for the the lower wattage ones (though, I overlooked the 400 WVDC as I look at the PDF... Doh! I could've saved 11 cents apeice darn it!). Finally, these were radial leads (side-by-side) and it would've been better to find an axial lead, but Xicon doesn't make a metallized Polypropylene in that value/voltage. They worked just fine anyway...

The polystyrenes film caps were Xicon (Mouser PN 23PS250). What's nice about dealing with Mouser vs. Digi-Key (although Digi-key has great people and does have almost everything you need, they didn't have these caps, believe it or not), there is no minimum order (Digi-Key charges an extra $5 or so).

John, good luck with the 4315's! It's not that hard to do. The first one is pretty tough, as you want to be careful, but the second one is a breeze. You'll be happy with the results and it does make a difference (not a huge diff, but a diff nonetheless). Don't forget to pre-tin the empty terminal tabs on both sides of each tab (it makes the soldering of the jumper wires and caps much easier).

[rek50]

Good Show!