L65 cab resto

[lodoc]

This JBL disease is taking time away from the car hobby...

I took a pair of L65's out to the shop to troubleshoot a component problem.
The odds-on favorite is a tube in the MC240.

The particleboard on the bottom of the L65's is showing some serious deterioration problems after 30+ yrs in challenging environments - inside, outside, damp, smoke-filled, etc. Though I have some experience with wooden boats, pinball machine cabinets and car bodies speaker cabs are not my strong suit.

Do I use a 2 part epoxy thinned 10-20% with xylene as a 'penetrating epoxy' for the first coat? Then follow up with 2 part body filler or thickened epoxy for the gaps / imperfections? Or just replace with real wood? And the paint?... it looks like low gloss enamel so I'm in my realm with finish coat.

The bottoms have been problematic since birth. The particleboard edge sits about 1 1/2 inches back. So the cabs have been front / top heavy forever. They are prone to falling fwd on irreg surfaces. What have others done to solve this problem. There may be some welding in this yet... a handle and front edge foot would be nice.

[johnaec]

Personally, if the bases are in pretty bad shape, I'd consider making new ones. And if you're not overly concerned with matching original specs, you could even make them with a little slope built in. I just checked mine, and it looks like making the front of the bases 1" - 1.5" higher than the rear would angle them up just about right. Of course, to do this correctly, it'd mean the bottom edges of the front and rear portions of the bases would also have to have a matcing angle on them. If you don't have the tools to do this correctly, I'd stick with the stock design. You could still make them longer, so the fronts would be closer to help with the balance problem.

As far as material, I'd just pick up some plain 1x4 pine. At least you wouldn't have a crumbling problem.

Good luck!

John

[edgewound]

lodoc...

I'm assuming you're talking about the riser base that the L65 enclosure sits on, and not the bottom panel of the cabinet itself? Yes they tend to weeble and fall on their face if bumped too hard or rumble through an earthquake. I've had several in my shop for broken grills and woofers after falling over like a drunken sailor in an earthquake here in CA.

Just replace the particle board with something more durable....maybe you could find a remnant of 13 ply baltic birch plywood and paint it with black epoxy paint.The L65 was designed to be like an end table....ya know glass top and all. I'd maintain the look as close as possible...maybe widen the base a bit for stability...just my preference...what ever works for you.

Thanks,
Edgewound

[johnaec]

The L65 was designed to be like an end table....ya know glass top and all.

I forgot about that - tilting them back would definitely be a problem, seeing as there's no lip in the back!

John

[lodoc]

I took off the grills on my L65's. I knew one of them was tired but was surprised at the extent of the deterioration. The grill was in 5 or 6 pieces. There was a pile of sawdust when I removed the fabric. The majority of the 'bottom' was melting away particle board. Now someone will probably make my day and tell me I could get new frames for about $10 each including shipping but I'm thinking there's probably no way I'm going to find replacements so I decided to fix them. I'm regretting not getting 'before' pics but wanted to share a repair that has developed in multiple stages.

I called on my old friend the WEST SYSTEM of epoxy. I lined up the chunks of grill as best as I could so they were somewhat flat and square with multiple layers of newspaper underneath. Soaked them down with epoxy thinned 10% with xylene to make a 'penetrating epoxy'. It really soaked into those pieces and the flaking off sawdust. I packed the gaps with fiberglass cloth. I Laid a layer or two of 'tongue depressors' on top to clamp them down tightly and allowed it to dry. Any major sins were corrected on subsequent line-ups, clamping , reinforcement and epoxy sessions. I repeated this several times to make the frame flat, square and uniform. The gaps and broken corners were repaired with epoxy mixed with filler. Then I took them to the belt sander and cleaned up the overflow epoxy and adhered newspaper and tongue depressors. After that step I used a DA sander with 120 paper to sand them until they were pretty. Here is the final product. I put tape strips to show the fault lines. Now they are ready for epoxy black paint. I plan to use a 3M spray adhesive to reattach the cloth. If it works for sail panels on headliners I suspect it will hold up on speaker grill. I'll use fresh velcro and staples. On the road again...`

[lodoc]

one more showing the location of the breaks before repair.