Trashed JBL L36 Decade Restoration - I Need Your Help!

Use a good quality oil, Watco is fine. Even with a coat of wax, the wood is going to change color because of any UV (unless they will only be used in a dark room,lol). I've mixed Watco colors to attain a certain result but if you're removing all the finish, the grain and brightness will be best with straight oil. BTW, Ace hardwares sell Lundmark brand waxes. IMO, they're better than Minwax.
 
Use a good quality oil, Watco is fine. Even with a coat of wax, the wood is going to change color because of any UV (unless they will only be used in a dark room,lol). I've mixed Watco colors to attain a certain result but if you're removing all the finish, the grain and brightness will be best with straight oil. BTW, Ace hardwares sell Lundmark brand waxes. IMO, they're better than Minwax.

Thanks for the response. Yes, in my experience oak (and cherry) get fuller/darker over time, where walnut gets lighter with exposure to UV. I'm really leaning to exchanging the Watco Golden Oak for Watco Natural. The Golden Oak adds a yellow tint that makes the finish look lighter to my eye - the opposite of what I want.

Thanks for the tip on the Lundmark waxes, there just happens to be an Ace Hardware store on my way to Rockler. I'll swing by tomorrow on my way to Rockler and see what they have in stock.
 
I second the use of Watco Natural if you're looking for a more oak rather than golden oak finish.
 
I second the use of Watco Natural if you're looking for a more oak rather than golden oak finish.

Watco Natural it is. I hope Rockler will accept the Golden Oak in exchange for the natural since it was opened in the store by an employee and recommended by him.
 
I also used my orbital on the L36s. The oak veneer was so hard that it was hard to even work it down with the sander. I had no fears about burning down the veneer. I used minwax light oak stain with a triple application. After that was thoroughly dry I did about three or four coats of tung oil. It came out looking great. I didn't replace the grill cloth, which is good, because our cats use it as the alarm to wake us up in the morning; so that we can follow them into the laundry and see that their food bowl is full@@@@@.
Every night before I go to bed I have to put up my cardboard shield.

When you get to the crossover, if you have not removed it yet, it just pops off with a putty knife or screwdriver. I tried to remove one of the old caps and it was so difficult that I ended up installing the rest over top of the old ones. Personally, I could not hear any difference. Good luck with your project. You will enjoy it when it is done.
 
Didn't make as much progress as I'd hoped yesterday. After removing the old grill cloth, I sanded off the old adhesive on the back sides of the grill frames. Probably not necessary, but I wanted the new adhesive to have a good, clean surface to bond to. The sanding also took off some of the black paint, so I had to repaint the grill frames. So, I'll let those dry for a couple days before I apply the new grill fabric.

I ordered my replacement crossover caps this morning. After quite a bit of research, here's what I ended up selecting:

Tweeter Series Cap - 3.0 Sonicap Gen 1
Midrange Series Cap - 6.0 ClarityCap PX
Woofer Shunt Cap - 2x - 8.2uF Mundorf ECap AC

My initial plan was to just go with Dayton Audio DMPC 5% caps in all positions. That would have only cost a little over $13 per speaker, but I thought this would be an opportunity to try some more highly regarded, but still affordable, caps - especially in the critical tweeter and midrange series caps. When selecting crossover caps, it's real easy to get tempted to move up the food chain. It's a slippery slope. There are so many options, it can get expensive quickly if you aren't careful The solution I ended up with only costs about $6.50 more per speaker (less than $20 in parts per speaker) than the Dayton 5% caps and is actually less expensive than going with Dayton 1% caps.

The Sonicap is highly regarded by both Polk and Klipsch aficionados (including Bob Crites). It's also highly recommended as a budget cap by Tony Gee on his Humble Homemade Hifi Capacitor Test page. Tony Gee also had good things to say about ClarityCap PX series as a good budget crossover cap. Finally, I decided to spend less and go with a well regarded, but inexpensive, electrolytic in the woofer shunt circuit. I also considered the Axon True Cap film caps in this circuit. Combining 13.0uF and 3.6uF True Caps in this position would have cost less than a dollar more per speaker than the Mundorf ECaps. I'll see how I like the sound with the Mundorfs. If I like it, I'm good. If not, I'll add some Axon True Caps to my next Parts Connexion order and rework one speaker so I can do an A/B comparison between the Mundorfs and Axons. I suspect the Mundorfs will sound fine and this won't be necessary.

Tony Gee also specifically recommends using 0.01uF Vishay MPK1837 as bypass caps for the Sonicaps:

"Putting a 0,01uF Vishay MKP1837 parallel to them (a good tweak for nearly any capacitor) can create even more detail and separation!"

The 0.01uF Vishay MKP1837s are currently on sale for $0.80 at Parts Connection. So, I'll probably pick some of those up to try as bypass caps on the 3.0uF Sonicaps and perhaps the 6.0uF ClarityCaps.
 
thanks for posting back.. looks like a little swapping and testing caps values. post back when you can. :D
 
Leave the stock caps alone, they don't age, and are better than the audiophool junk you've been tricked into buying.
 
I beg to differ on the caps logic.

It doesn't matter, the audiophool (TM) junk caps were already ordered and have arrived. It may (or may not) be a waste of my time and money, but it's my time and money. The caps have arrived and I will proceed with the recap. It's not like I spent $200 per speaker on boutique caps. The caps I selected ranged in price for $0.80 to $9.76 each. The total came to just under $20/speaker.
 
After much searching and testing of various finishes, I have decided to go a completely different direction with the finish and grill cloth for my L36 Decades. After hours of sanding, the natural oak veneer was just so beautiful, I wanted to preserve, or even enhance, that look. When searching for grill cloth, I found a thread on the Lansing Heritage forum that included photos of some stunning L300 Summit speakers that have served as my inspiration:

attachment.php

attachment.php
attachment.php


The owner of those gorgeous L300 Summits mentioned he ordered the beige grill cloth from speakerworks.com. They happen to be located right here in Oregon. So, I placed an order for one yard (more than enough for 4 - L36 grills) for $11.95. That thread was almost 6 years old, but I registered at Lansing Heritage and sent the owner of those Summits a PM asking about the specific finish he used on his cabinets. He replied in less than 24 hours with the details - WOCA Worktop Oil - White. I ordered a can this morning. It should be here in about a week. I read the instructions and watched the video and it looks very easy to apply. Since it's an oil finish, it's a one step process.

Of course, my L36 Decades are a more modest design than the legendary L300 Summits, and this finish and grill cloth were not factory original options for the L36, but I really like the look, and while not historically accurate, it will make my L36 Decades unique. Some purists may scoff, but it's not like the L36 Decades are rare, and again they are my speakers to do with as I please.
 
More updates...

Progress continues to be slow, but steady. The most significant progress since my last post is the crossover networks have been recapped and the L-pads cleaned. Here's some photos:

Replacement Caps (to tp bottom) 3uF Sonicap Gen1 Tweeter Series Cap, 6uF ClarityCap PX Midrange Series Cap, 8.2uF Mundorf E-Cap (2 per speaker = 16.4uF) Woofer Shunt Cap:

JBL_Decade_Caps.jpg

Original Crossover - a bit of a rat's nest on the wiring:

JBL_Decade_Crossover_1.jpg

Close Up of Original Caps (with the rat's nest pushed out of the way):

JBL_Decade_Crossover_2.jpg

L-Pads after Cleaning with Deoxit D5:

JBL_Decade_Crossover_3.jpg

Complete Recapped and Reassembled Crossover:


JBL_Decade_Crossover_4.jpg

As you can see from the last photo, I used both hot glue and zip ties to hold the new parts in place. I also changed the positions of some of the parts to clean up the wiring. I have not installed the 0.01 Vishay MKP1837 bypass caps on the tweeter and midrange caps. They haven't arrived, yet. I may try them with and without the bypass caps, or just add them when they arrive and button everything up.

The L-pads were in surprisingly good shape. In my research, I've seen many horrible photos of filthy, corroded and even burnt out JBL L-pads, and I also read much advice to simply not bother cleaning them and just replace them with equivalent new L-pads from Parts Express. All four were surprisingly clean inside, and after cleaning them thoroughly with a couple rounds of Deoxit D5, a small brush and some compressed air, they sparkle like new.

Since the speakers were not in usable condition when I got them, I have never heard them with the original caps and uncleaned L-pads. Perhaps none of this was even necessary, but in the end, I'm spending a lot of time and a bit of money on these and I figure worst case, I did no harm and may be able to keep them going another 40 years before opening them up again. At that point, they will likely be someone else's concern.
 
Last edited:
An update on the drivers...

As mentioned previously, I won a replacement LE5-6 midrange on eBay. It arrived on Saturday. In the process of searching for a replacement LE5-6, I came to be in contact with a professional JBL repairman in the Bay area, and after a few text messages and phone calls, we stuck a deal. I traded him a 044 tweeter from an orphan JBL 4411 in exchange for parts, labor and shipping on refoaming the surrounds on the 125A woofers and replacing the dented dust caps on the LE25-4 tweeters.

I was originally planning to do all this work myself, but after reading about the tighter than typical tolerances on the 125A woofer voice coils, I decided to have this work done by someone with a lot more skill and experience. Turns out he's a great guy and a very knowledgeable and experienced JBL repairman. I haven't received my drivers back yet, they should be here around the end of the week, but have been in daily contact with him. He also checked the spiders on the 125A woofers for any signs of sagging or other problems and he reported that the spiders are in remarkably great condition.

So that, combined with the condition of the L-pads, makes me reconsider the use of the word "trashed" in my thread title. In spite of the completely deteriorated woofer surrounds, the torn midrange and the dented dust caps on the tweeters, the insides of the speakers were in remarkable condition - certainly worthy of this restoration effort.
 
It's been cool and damp here for the last couple days. So, I haven't attempted any finish work on the cabinets. I don't like to paint, stain or varnish under less than ideal conditions. Besides, the new WOCA Worktop Oil won't be here for several more days, so I still have time for the final cabinet prep. I'm trying to decide if I want to completely repaint the baffles, or just touch up the edges. We'll see.

The beige grill cloth from speakerworks.com arrived today. It is definitely thinner and more transparent than the burnt orange fabric I received from Huntley, but I like them both. The look and heft of the burnt orange fabric is a great match for the retro, very 1970s look of the original fabric, while the beige fabric definitely has more of a sleek, modern look and feel. I'll post some photos of the grills when I get the new fabric installed.
 
We await with 'bait breath'.. :D Might ask your better half.. if it doesn't match the decor? your up shi* creek and cost. :D Just speaking color decor wise.

no telling how many a man purchased the 'leg lamp' only to bury it... living room is usually her end zone. :D
 
I am skeptical of proclamations about what works and what doesn't without much of (or any) explanation as to why. I'm not sure what caps are in these originally, but I've never recapped an old speaker that didn't sound better afterwords.

I'm glad you went with the recone kit on GordonW's recommendation, too. There's a guy who has repaired a lot of speakers. Aftermarket is not necessarily inferior, especially when you have a broken thing you want to fix. Now, I would never pull all the drivers out of a cabinet thinking I could improve on things, but sometimes repairs are necessary.

I bought aftermarket titanium diaphragms for my Klipsch tweeter horns and they sound better than I remember the originals ever sounding. :dunno:
 
The grills are done, but I have not reinstalled the badges. It probably sounds blasphemous to JBL aficionados, but I think I actually like the clean badgeless look.

I haven't made any progress on the cabinets. It's been cold and raining here and I don't like to apply paint or finish when there is excessive humidity. It's supposed to be warmer and dryer tomorrow and Monday. So, hopefully I can make some progress there.

But, the big news is the mailman just dropped of the repaired woofers (new foam surrounds) and tweeters (new dustcaps). They look great. Picks to follow.
 
I haven't applied the WOCA white Worktop Oil yet, but here's a couple sneak peaks at what the beige grills look like on the sanded cabinets:

JBL_L36_Decade_Beige_Grills_1.jpg

JBL_L36_Decade_Beige_Grills_2.jpg

I need to get some better photos. The first one has a green cast and the second one has shadows and moire patterns on the grills that aren't present in real life.

The cabinets should be a little lighter after applying the WOCA Worktop Oil. So, to badge, or not to badge, that is the question? I haven't installed the JBL badges on the recovered grills. They would go in the upper right corners if I did. Opinions?
 
Last edited:
Ohhhhhhhh! those are awesome!!!. Make the badges removable!. A thin steel plate siliconed behind the badge and a small magnet
on the other side of the fabric!.
 
Finished these early this morning and have been listening to them non-stop since. Here's a photo of how they turned out:

JBL_L36_Decade_After_1.jpg

I liked turboyam's idea of removable badges, but once the grill cloth was installed, I didn't want to risk snagging the cloth to drill a hole in the frame to mount a magnet. So, althout the finish and grill cloth cover isn't original for this particular model, I still decided to honor their heritage and install the JBL logo grill badges:

JBL_L36_Decade_After_2.jpg

I put a lot of hours and sweat into these, but am very pleased with the way they turned out, both in how they look and how they sound. I'll post some more photos and a description of the process I followed in the next day or two.

Thanks to all who participated in this thread. Your guidance and suggestions were appreciated. I am now enjoying my first ever pair of JBL speakers.
 
Last edited:
Back
Top Bottom