4311 Restoration

[Mike F]

My vintage JBL journey continues. This time it`s led me to a pair badly abused and neglected pair of WX-As.
These were originally installed in a regional Canadian Broadcasting Corporation studio but likely sustained the damage after being decommissioned.
As you can see, the cabinets were in a sad state.
The drivers didn't fare much better. One 2213 had a large tear in it`s cone accompanied by a footprint and one of the LE25s had the familiar finger modification done to its dome. Thankfully, the LE5-2s were unharmed.
I managed to undo the LE25 finger mod successfully using the water and suction method, but another woofer had to be sourced. The grille frames were in good condition but the cloths were not.

[Mike F]

I`ve restored badly damaged JBL cabinets before, older models used much thicker veneers like back in the L36 era which gave you more to work with, but the veneers used in this vintage were noticeably thinner and therefore, less forgiving.
These cabinets were beyond repair and needed a re veneering. The problem with that was, I`ve never done it before :(
After some research, I thought I`d give it a try, the speakers couldn't possibly end up in worse shape than they re already in.
Before the new veneer could be applied, deep scratches, gouges and bashed corners had to be repaired. What a long and dusty process that was but it needed to be done.
I settled on the wood glue and iron method, bought some Black Walnut veneer and got busy.
That too, proved to be quite the task but the result surpassed my expectations :)

[Mike F]

With the veneering out of the way, I thought to myself:
"I`m going to need some tall stands to get the Mids and Tweeters anywhere near a 37 inch ear level!"
Sure one could always invert the cabinets and call it a day but sadly, my OCD would never allow for that, there was just no way that I could have gotten used to backward and upside down script, despite the sonic benefit.
Since this pair will not be seated on a meter bridge any time soon and after a little brainstorming session I figured that with a slight baffle modification, I could achieve an optimal tweeter height and proper script orientation.

Naturally I was concerned about the consequences of such a modification, particularly those of the Audio Gods and what they would have to say about messing with a classic design but I figured the pro`s outweighed the con`s and to keep the Gods possible wrath at bay, I made the mod completely reversible.

The crossover and L Pad assemblies (3112a)were already removed waiting to be re capped and cleaned so it was a good time to make the move. I decided on separating the caps and L Pads and making new panels in order to avoid
cutting up the original plate to clear the mid range enclosure sub-enclosure.
That also made for more flexibility in terms of component and wiring choices.
The new panels were made from .25" Baltic birch. A thin sheet of foam rubber was glued to the surfaces that contacted the interior baffle to eliminate vibration.
Next up was the tricky part, boring the baffles for the L Pad knobs. I made a cardboard template for the positions of the 4 mounting holes preserving, the original spacings.
The knob holes measured in at around 22mm, a large hole in a .75+ inch baffle. At a friends suggestion, a 7/8" Forstner drill bit was used for the task at hand. A few practice holes were drilled into some scrap wood prior to the real thing just to get a feel for things. That turned out to be time well spent, the holes are clean and straight!

[hjames]

Its looking VERY nice ...
I hope you are planning to saw a round plug from scrap wood or a dowel or something to glue/plug the old pair of holes under the label-plate?




The crossover and L Pad assemblies (3112a)were already removed waiting to be re capped and cleaned so it was a good time to make the move. I decided on separating the caps and L Pads and making new panels in order to avoid
cutting up the original plate to clear the mid range enclosure sub-enclosure.
That also made for more flexibility in terms of component and wiring choices.
The new panels were made from .25" Baltic birch. A thin sheet of foam rubber was glued to the surfaces that contacted the interior baffle to eliminate vibration.
Next up was the tricky part, boring the baffles for the L Pad knobs. I made a cardboard template for the positions of the 4 mounting holes preserving, the original spacings.
The knob holes measured in at around 22mm, a large hole in a .75+ inch baffle. At a friends suggestion, a 7/8" Forstner drill bit was used for the task at hand. A few practice holes were drilled into some scrap wood prior to the real thing just to get a feel for things. That turned out to be time well spent, the holes are clean and straight!

[Mike F]

Its looking VERY nice ...
I hope you are planning to saw a round plug from scrap wood or a dowel or something to glue/plug the old pair of holes under the label-plate?

Oh absolutely, details of which will appear in the upcoming "Crossover" episode.
Stay tuned :)

[Mike F]

The cross over was next in line. While newer cross over designs undoubtedly improve upon the systems response, I chose to stay with the all too simple original layout but with modern components.
After some research, Clarity Caps were found to be considered a smooth sounding upgrade to the 35 year old originals so they were chosen.
The L Pads cleaned up nicely and re used but the original wiring just had to go. It was replaced with 12 AWG twisted pair going from binding posts to cross over input and woofer input, 16 AWG twisted pair everywhere else.
All fast-on connectors were crimped and soldered.
The binding posts too were upgraded to a nice WBT type set that accepts more modern speaker cables.
Some might think the re worked cross over a little over built but I figure that if it`s worth doing ,it`s worth over doing http://www.audiokarma.org/forums/images/smilies/smile.gif
The new cross over and L Pad panels were reinstalled and lined up perfectly.
The original panels L Pad mounting holes were plugged up and reinstalled back into their original locations.

[tomee]

The veneering looks excellent! Where did you buy your veneer? Also, how did you repair the bad corner before veneering? (I'm working on a pair of L100T that could use new veneer but I've been patching the bad corners with epoxy wood filler with plans to stain or paint them.)

[Mike F]

The veneering looks excellent! Where did you buy your veneer? Also, how did you repair the bad corner before veneering? (I'm working on a pair of L100T that could use new veneer but I've been patching the bad corners with epoxy wood filler with plans to stain or paint them.)

I bought the veneer from a local lumber yard that carries a more exotic variety of wood than your average big box renovation center.
http://www.langevinforest.com/en

The veneer I used was Black Walnut. It is quite light and relatively featureless in raw form but apply some Watco oil and the transformation is stunning as you will see shortly.
Even though the cabinets were re veneered, light to moderate scratches were treated to some LePage`s wood filler.
Gouges and corners were repaired with believe it or not, Bondo
automotive putty.
In most cases, several thin layers were applied and shaped, lots `o dust.

[SEAWOLF97]

I love seeing the vintage speakers regain their former beauty. :applaud: JBL's of that era were very nicely crafted , hence their retention of value.

(can't even see black)

[georgebrooke]

Congratulations on a great job. The original mistreatment was extreme and it is great to see those classic speakers back in operation and looking like they should

[Mike F]

The original grilles were in a sad state. The cloth had begun to separate from the frames and there were several tears and holes in them. Luckily, the frames were solid.
I had on hand some Navy and Electric Blue cloth from a previous project that never materialized but couldn't decide which to use, so I made another pair of frames and used both :)
They turned out better than anticipated so I`m temped now to build a Black pair and a Tan pair, grilles for all seasons.

[Mike F]

Even with the new midrange and tweeter arrangement, it was difficult to find a pair of suitable, off the shelf stands. Most models are geared toward modern bookshelves that are all but useless for vintage JBLs, being too tall with too small a footprint. The closest to ideal that I came across were from Target Stands.
They have some very nice, sturdy metal post models but at close to $500 a pair..........it was time for some more DIY.

Aside from the substantial cost savings, building your own stands gives you the option of customizing critical dimensions to suit your requirements exactly.
Due to my limited woodworking skills, tools and working environment (my kitchen), the design needed to be kept simple.
I went with two 1/2" pieces of 12"x12" Baltic Birch panels sandwiched together to form the bottom plate, a single length of 3.25" square solid Cherry post supporting a 12" x 12", 3/8" thick top plate.
The center post was offset a little towards the back just to give it a less boring appearance.
Stabilization is accomplished with four, 1 and 5/8" long chromed large headed 1/4-20 threaded bolts mated to T nuts on all four corners.
I also found a use for some JBL badges too. The stand height minus the spikes is 16" which bring the mids and tweeters to 36". Perfect!

[Mike F]

So this is what they look like now :)

[Mike F]

A couple more

[Mike F]

:)

[high sky]

The look very good, hope the sound as good as they look.

Best regards

[macaroonie]

Very nice indeed :applaud:

[Mike F]

Thanks guys. I haven't had the chance to do much critical listening but from what I have done, I`m quite pleased with the results thus far.
After ensuring the polarities were correct, I ran some pink noise and took some near field measurements.
I was surprised to see how smooth and how high the 2213 went. I sacrificed a little in the 4-6K region to avoid the LE5-2s 6.3K nasties by running the LE25 at an equal level to the 2213 and just sneaking the LE5-2 in afterwards, it`s a good starting point.
Didn't take much in terms of L Pad rotation either as can be witnessed by their positions in the photo`s.
The ClarityCaps do seem to sound smoother than the Solen caps I used in another pair of 4311s and L36s before that.
The "right side up" mod too was worth the effort as it is critical to get the mid and hi drivers at a good level. Its surprising what a difference a couple of inches in altitude can make.

[Mattv228]

A couple more

I have to ask. I just saved some JBL 4311 from going to trash at work and was wondering how well they paired with the 700B. I seem to have the exact same set up but haven't tested them on my 700B. I think my 4311s need to be recapped but that's the only flaw.

[Mike F]

I have to ask. I just saved some JBL 4311 from going to trash at work and was wondering how well they paired with the 700B. I seem to have the exact same set up but haven't tested them on my 700B. I think my 4311s need to be recapped but that's the only flaw.

I briefly drove the 4311s with the 700B with very good results but then again, this is not your fathers Phase Linear. I installed a White Oak driver board, new output transistors, input coupling caps, reworked grounding scheme etc etc which transformed the amp significantly from stock form. A BGW 750B ran them for a while too but a Yamaha PC2002M was paired for the most part.

That said, I cant imagine a bone stock Phase Linear not being up for the job, but do your self a favor and load protect the amp in the event it decides to go supernova.