Building My Own L100 Cabinets?

[Ralphh]

My thanks to all of you for your response and opinions. I now have all the required components and I'm in the process of creating CAD construction drawings from measurements taken from a friends L100's. Since he doesn't want to remove any of the drivers from his speakers, I have the following additional questions that I hope someone can help me with. 1) Is the front panel (baffle) 3/4" or 1" thick? 2) What is the depth of the enclosure tube that is behind the midrange driver? And 3) Are the wires to the midrange driver sealed where they pass thru the wall of the enclosure tube?

Your response will be greatly appreciated.

[JuniorJBL]

I would think that almost any le5x from a later vintage L100 L250 etc. would have the same depth tube as they usualy use the cutout from the baffle to seal the rear of the tube. If this is the case I can measure my L250's and give the measurement

[pmakres1]

Are the wires to the midrange driver sealed where they pass thru the wall of the enclosure tube?

I can tell you that in my L220's the wires to the midrange driver are sealed where they pass through the wall of the sub-chamber. Some type of grey putty was used, probably silicone.

This is also the case with my 4313B's.

Peter

[Akira]

since i own a touring company MDF is out of the question. we use 13ply russian birtch. very expensive but every bit as good as MDF and quite superior for strength and bracing, especially when constructing a small box...plus it makes a good natural finish...no veneer.
my L100's use 3/4" walls with a 1" baffel...don't know why
p.s. i would use a 2405 slot, the absolute best high end ever. i don't feel the 6K cross over point is bad, even though the recommended point is 7K. the gain is reduced and the rough oscillating sound comes in at 5K.

[Ralphh]

Thanks again for everyone’s input. I now have all the materials and plan to start construction of the cabinets in the next few days. I am using 3/4" MDF for the sides, top, bottom and back, 1" Baltic Birch for the front, and 2-ply walnut veneer for the sides, top & bottom from Rockler Woodworking. I'll post pictures as construction progresses.



Now if “Sonofagun” would start making the foam grilles for the L100’s, I’d be complete.

[Ralphh]

Well, this project has certainly not gone as fast as I would have liked, mostly due to summer family activities. And not having access to a table saw doesn’t help either.
I have cut the top, bottom and side pieces for two cabinets from ¾” MDF. These have been cut to the required depth, but are currently longer than the finish dimensions. I cut these with a circular saw and a metal straight edge with excellent results. I decided to make these cabinets ½” deeper that actual L100’s to further distinguish them from the real thing.
Next, I applied the walnut veneer to one top piece with contact cement. Once the cement had cured for a week, I set up and cut this piece to the finish length with corners cut to a 45 deg. bevel. I first laid out the cut line, and then sliced thru the veneer with a utility knife. I then applied a piece of masking tape along the cut line to hopefully prevent any breakout of the veneer from the upwardly rotating circular saw blade. This worked perfectly and resulted in a very clean cut. I’m also using 60 tooth carbide tipped blade in my circular saw.
Another change I’m making in the construction of these cabinets compared to the original L100’s is cutting a rabbit in the front edge of the top bottom and sides for the front baffle to sit in. I have cut a 3/8” x ½” rabbit into the above described top piece, and a corresponding one will be cut into the edge of the 1” thick front baffle panel. This will allow the front panel to site flush with the side panels and give a stronger joint.
With the success of this test piece, I now plan to veneer and cut the remaining pieces. I will post pictures of the construction when I begin the assembly.

Once again, thanks for all your input.

[Titanium Dome]

...and post those pictures!

[Lancer]

p.s. i would use a 2405 slot, the absolute best high end ever.

If that were true, I'd be using them.

[Zilch]

If that were true, I'd be using them.

Yeah, me too.

I don't even have any.

[Maybe that's the problem.... ]

[Lancer]

I don't even have any.

[Maybe that's the problem.... ]

Well, maybe you should keep a pair around for kicks.

[Akira]

If that were true, I'd be using them.

it's all about the texture that a driver imparts into the mix. the slot sounds like pure air; it opens up the box... no sizzle, spit or sparkle. (but, for best performance they really should be crossed over at 10K) absolute best on hi-hat, 21" rock ride (every drummer, and engineer knows what that sounds like) acoustic guitar harmonics and breathy vocals. for all of these reasons i don't like 044's, but that's just my preference. SO...what do you prefer, and back it up.
new drivers from all high end companies boast 30K plus response...meaningless if the texture isn't there, but maybe they sound great. never heard the new beryllium HF drivers, anyone have any comments.

[Lancer]

but, for best performance they really should be crossed over at 10K

And without any passive components between the driving amp and the 077/2405. Use an electronic crossover in front of a very low power amp such as a chip amp. Amps with turn on transients will damage the ring diaphragm.

SO...what do you prefer, and back it up.

I simply don't have the time and inclination to get into this with you. Pretty much everything JBL makes today beats up the old ring radiator. I will say that I cannot, off the top of my head, think of anything JBL that can beat the 077/2405 from 10k to 20k with maximum SPL as the requirement.

Some will immediately pick up on the old saying - "JBL always had the bass, that wasn't the problem..." For years, the 077/2405, warts and all, was simply the best thing JBL had regardless of intended application. That limitation went away with the introduction of the 066 many, many years ago. The old slot loaded ring radiator is early 70's technology and JBL has come a long way in the high frequency transducer department. Yes, the 077/2405 is neato, groovy, cool, whatever, but it hasn't been the only game in town for a very long time.

[Ralphh]

Finally, here are some pictures of my progress on this project. I haven’t glued the front baffle to the box yet. I plan to install the fiberglass insulation to the box sides and back, and install the port tube and midrange driver enclosure to the baffle before it is installed.

[sonofagun]

Hmmm...interesting. Here's a thought:

With the combined talent and know-how of all here, we should be able to come up with an updated, SOA retromod version of the L100. I can furnish new grilles*. I'm speaking of a redesigned version making construction easier and using new drivers (from any OEM maker) and x-overs to give better performance than the original. Perhaps eliminating the grille frame (with flush mounted drivers no frame is needed) - no diffraction effects.

Whadaya think?


Particle vs. MDF - PB is ok as long as it's high density cabinet grade. Whatever you use here's a tip for stronger joints:

Prime the pieces to join with a slightly thinned down version of the glue first; let soak in 5 - 15 mins; then add full strength clue and clamp - makes for stronger joints. Screws sometime actually weaken joints since they can fracture the wood - modern glue joints are stronger than the wood itself.

*Currently am working with a co. with a CAD/CAM machine to automate the manufacturing process. Can solve L100 grille production problems.

[Ralphh]

Well, the cabinets and grill frames are finally done. Here are some pictures taken before the finishing begins.