Jbl L100 Crossover

As mentioned, the L-100 has a few weak spots, some of which decreased over the years with new versions of the L-100, other models and other drivers. Commonly claimed weak spots of the L-100 are: The JBL. Speaker Crossovers, Parts, L-Pads, Repair Accessories - We stock high quality 2 Way Crossovers, 3 Way Crossovers, L-Pads, and Protection Fuse Bulbs fo. JBL Factory Replacement Crossover, Control 28T, 338146-001 (1) In Stock: $55.00. JBL Factory Replacement Crossover. JBL Century L100 Restoration. 4.2015 - By Greg Roberts Page Two. The first thing I did was to remove the drivers and store them away. Here's a picture of one of the beautifully made woofers. Tweeters and mid drivers Crossovers, if you can call them crossovers. Details about JBL L100 Century Crossovers See original listing. JBL L100 Century Crossovers: Condition: Used. Ended: Oct 25, 2020. Winning bid: US $72.11 9 bids Shipping: $14.00 Expedited Shipping See. JBL now has a perfect answer, the JBL L82′. Honey, I shrunk the JBL L100’s. Today’s JBL L100 is in fact a reissue of the L100 Century of the 70’s where the drivers and crossover have been completely redesigned. The L100 of those days was in turn a consumer-version of the legendary 4310 studio monitor.

JBL Century L100 Restoration

4.2015 - By Greg Roberts

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The first thing I did was to remove the drivers and store them away. Here's a picture of one of the beautifully made woofers.

Tweeters and mid drivers

Crossovers, if you can call them crossovers. Two caps, one for the mid and one for the tweeter. Two potentiometers for controlling the output level of the tweeter and mid. No components on the woofers - they run full range. I think there's room for improvement here.

Crossover and plate from the front of the speaker

The thin alumimium plates came off easily with a heat gun and putty knife

One hour to remove components.

Next up - cabinet repairs. The cabinets are sanded with a random orbit sander using 80 and 120 grit discs. This 'cleans up' the surface of the cabinets and gives me a chance to inspect and find all the trouble spots. I remove any loose veneer or crumbling MDF with a putty knife, exposing holes and raw spots that will need to be filled and sanded. I use epoxy filler like this for the holes

I use a lower viscosity epoxy glue for loose pieces that I want to glue in place before filling. On the backs of these speakers, there's a recessed area that leaves a lip, or reveal all around the back. Damage to this inside lip area can be very time consuming to fix, so I prefer to keep that lip intact and repair with glue, rather than digging it out and filling with epoxy. This saves a lot of time and money. In this picture you'll see where I've used the epoxy glue in a piece of the lip that had cracked and was loose, clamping it in place to set up before filling with the heavier epoxy filler.

I also use the lower viscosity epoxy to fill in loose seams at the corners of the speakers. Note in this picture how the joinery at the seams is not simply a 45 bevel, but there is a tongue and groove part as well.

If I can get the putty knife more than 1/4' into the seam, I use the lighter epoxy and push it down into the seam to re-glue it

Here's a bad spot on the inside of the lip on the back

Another long crack on the lip - lighter epoxy, clamp to hold, then fill with epoxy filler

The repairs look scary sometimes, but in the end, these will sand up nicely and provide a flat, solid area for the veneer to hold to

Here they are, initial sanding done, initial repairs done - 2 hours 15 minutes for this work

I waited a few days before sanding the epoxy, to let it cure really good. Normally you can sand this stuff in 24 hours, but since I put such a thick layer on, and because I had other projects to work on anyway, I figured I'd give it some extra time.

These images show the first coat repairs sanded. Note the voids and rounded corners which will need an additional coat of epoxy to bring perfectly flat and sharp.

On the back edges, I tried to make repairs to the broken areas that would NOT interfere with the inside revealed edge of the back. Once that inside edge is damaged, it takes a lot more time to repair. Here's that really bad back edge damage that was repaired without getting into the inside reveal. Had I broken that piece out, this five minute repair would have turned into a half hour repair.

This next series of photos shows that one back edge reveal damage that needed repair. Very light filler to start, so the sanding is easier. Using a hand sanding block with 80 grit paper. Sanding very carefully up to the edge of the tape. Another light coat of filler. I'm hoping just one more coat after this will do it.

I got to talk to my customer on the phone today, and we made some decisions about this project. He really liked how the Sapele/cane grill cloth looked on the JBL restoration that I did many years ago. In fact he watched that restoration back when I did it, and has kept track of my work ever since, just waiting for the right time to have his speakers done. We've decided on Rosewood veneer with cane cloth for his speakers. I will be adding trim to the front of these cabinets and in-setting the grills as I did with the older restoration.

By the way, my customer mentioned that he was reading the comments on the Lansing Heritage Forum thread about this project, and he told me that this was definitely a labor of love for him. He's had these speakers for many years, through college and everywhere in between, and so he's very happy to finally be able to bring these speakers back to new, or even better than new condition. He'll be enjoying these for many years to come. He knows he could buy L100 speakers in decent condition and for a lot less money than this restoration is going to cost, but they wouldn't be 'his' speakers, and they wouldn't have Rosewood veneer, cane grills, wood trim on the fronts, upgraded crossovers, and be in perfect condition. He feels the money spent for these things will be money well spent. This is exactly why I'm in this business, and I'm happy to be offering this level of service to my customers.

So, since we're adding trim and using different grills, and we're not going to be using the potentiometers on the crossovers anymore, many of the holes in the fronts of the speakers need to be filled in.

One hour for sanding and second coat epoxy

Corners are sharpening up nicely

Small third coat of epoxy is on

I cut the trim pieces for the fronts out of MDF.

One hour for sanding, third coat epoxy and cutting trim for fronts

I know this project so far is a bit tedious, but it will start to get more exciting very soon as we get into the veneering process. So just hold on, more to come!

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Manual Library / JBL

Loudspeaker System (1970-73)

Description

When it was found that musicians, engineers and other discriminating professionals in increasing numbers were purchasing the JBL studio monitor for home use, JBL introduced the L100 - acoustically identical to the studio monitor, yet offering provocative styling appropriate to the home environment.

Truncated pyramids of the Quadrex 2 grille dramatize unique lineage and advanced engineering of the L100.

New methods of sculpting semi-rigid foam material gave JBL the freedom to explore texture, color and shape. This reticulated (open-pore) foam - substantially the same material used for quality microphone windscreens - has been proven to transmit sound as well as even the most acoustically transparent grille cloths.

The grille frame and loudspeaker system enclosure are finished in hand rubbed oiled walnut on all four sides and can be placed horizontally or vertically.

Specifications

Type: 3 way, 3 driver loudspeaker system
Power Handling: 50W
Crossover Frequency: 1500, 6000Hz
Impedance: 8Ω
Sensitivity: 78dB
Bass: 1 x 300mm
Midrange: 1 x 130mm
Tweeter: 1 x 36mm
Grille: blue, brown, orange
Finish: oiled walnut
Dimensions: 362 x 597 x 346mm
Weight: 25kg

Type: 3 way, 3 driver loudspeaker system
Power Handling: 50W
Crossover Frequency: 1500, 6000Hz
Impedance: 8Ω
Sensitivity: 78dB
Bass: 1 x 123A-1 Aquaplas
Midrange: 1 x LE5-2
Tweeter: 1 x LE25
Grille: G100 cloth
Dimensions: 362 x 597 x 346mm
Weight: 25kg

Type: 3 way, 3 driver loudspeaker system
Power Handling: 50W
Crossover Frequency: 1500, 6000Hz
Impedance: 8Ω
Sensitivity: 78dB
Bass: 1 x 123A-3 Aquaplas
Midrange: 1 x LE5-2
Tweeter: 1 x LE25
Grille: G100 cloth
Dimensions: 362 x 597 x 346mm
Weight: 25kg

Downloads

instruction/owners manual - rcalvill

technical manual - The SuperStorm

100A technical manual - The SuperStorm

100A (late) technical manual - The SuperStorm

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