Looking for ID of JBLs I just bought

[Lucas Membrane]

Posted this to vintage asylum with no response:

No visible model numbers. They stand 19 3/4 inches tall plus about 3 3/8 for the stand-up base on the bottom. They are 27 3/4 inches wide and not too lightweight, maybe 60 pounds or so each. The drivers are a 15-inch LE-15A, a 4-inch cone mid with 58G stamped on the back and the aluminum foil dustcap on the front, and some little (direct radiating?) tweeter that is a black plastic circle a little smaller than the mid with a slit down the middle that reveals a corner of what looks like clear plastic or plexiglass. As the woofer foam is kerblooie, I have not tried to hook the speakers up to see what or who comes out.

When I looked at the front of the baffles, I thought that maybe the boxes were home made, as they came out of a place with lots of shop equipment and the fronts of the baffles around the drivers look to be covered of wallpaper displaying line drawings of naked people. Then I see that JBL used to make things called Olympus and Apollo and such, so maybe not, I don't know.

There are two different JBL crossover-type inputs on the back of each box, like they are set up for bi-wiring, bi-amping, or by, by, birdie. These look to be the standard crossovers from JBL from around 1970 for the LE15A and their mids and tweeters.

The grill situation is also unusual. They have a burgundy cloth that is attached on only the top and dangles in front of the drivers and illustrated baffles.

These are JBLs with no port. IIRC, JBL used to said that all JBLs are ported. I can't find one.

Very luckily for me, the standard questions to ask in a situation like this are exactly the ones that I want to ask: (1) What model, if any, are these? (2) Any good? (3) Should I plan on recapping all those crossovers? (4) Any reason not to use generic surrounds to replace the foam? (5) Anything to do to make them better than whatever they already are?

TIA for any info

[oldsoundz]

http://www.lansingheritage.org/

Check out the library at this site. Tons of info and probably what your looking for.




You might also post pictures.

[grumpy]

heh.... I was hesitating to ask for pictures. :eek:

Nothing I can come up with from memory would have a LE15A, LE5-?
and an 077 tweeter in box of those dimensions (guessing on parts from
description).

[4343]

Very luckily for me, the standard questions to ask in a situation like this are exactly the ones that I want to ask: (1) What model, if any, are these? (2) Any good? (3) Should I plan on recapping all those crossovers? (4) Any reason not to use generic surrounds to replace the foam? (5) Anything to do to make them better than whatever they already are?

TIA for any info

...
3.) What crossovers are in there?

4.) Go here: http://www.audioheritage.org/vbulletin/showthread.php?t=469
The best don't cost more.

5.) Port 'em?

[Lucas Membrane]

heh.... I was hesitating to ask for pictures. :eek:

Nothing I can come up with from memory would have a LE15A, LE5-? and an 077 tweeter in box of those dimensions (guessing on parts from description).

I think I have read that JBLs all had ports if made by JBL. If that is true, I must have a home-made set of boxes. I believe the dimensions work out to 5 cu ft sealed. The mid and tweeter look just like those in Jubals, which I think are what you said.

Is the LE15A a good choice for such an enclosure? If not, is there another vintage JBL woofer that would do better?

Refoaming the woofers should not be a big problem for me, as I have done about 20 or so pairs before.

My biggest worry and unknown is the crossovers. I'm guessing that my best guess is that the crossovers are roughly 30-40 years old. Does that make it dead certain that the capacitors need renewing? Can I hope to find an easily accessible 2-dimensional layout with capacitors labeled clearly as to capacitance when I open up the crossovers? I've done a fair amount of tinkering with electronics over the past 50 years, but I'm fairly low on manual dexterity and visual acuity, so I surely don't need to be messing around in a complicated knot of parts if I cannot even tell for sure what is what. As these are split into two crossovers for bi-amping, bi-wiring, or whatever, I can hope that there are not too many parts in too small a space.

If the crossovers look like too much trouble for me to repair, I would think that my best choice if it is worth it would be to try to salvage the coils and rebuild the rest from new parts on bigger circuit boards. Are there schematics for these crossovers in the library on this site?

My other biggest worry is how these things are going to sound. Worth the trouble?

[BMWCCA]

Somebody had to say it: :useless:

[Lucas Membrane]

...
3.) What crossovers are in there?

4.) Go here: http://www.audioheritage.org/vbulletin/showthread.php?t=469
The best don't cost more.

5.) Port 'em?


I do not see model numbers on the crossovers, but they look pretty much like LX5 and N7000 in the catalogs. There is a small 2-position toggle switch to the left of the HF control knob on the back of the low-frequency crossover. What does that do? What is signified by the B and R markings next to the phone jack inputs to the LF crossover?

One of the catalogs shows a cross-section cutaway of the crossover. I don't think that I'll like working in that space. What are the chances that the L-pads or pots are in usable condition? They do seem to crank smoothly.

The drivers are LE15A (for sure), and probably 2105 and 077.

So, what are good port dimensions for an LE15A in a 5 cu ft enclosure? If I port it, I should pull out all the stuffing and cover 3 of the walls with some kind of other deadening material, right?

When I look at the price lists, I see that LE15A was the most expensive woofer, so I'll guess that there is not much reason to look to replace it.


Thanks

[Feroce]

I do not see model numbers on the crossovers, but they look pretty much like LX5 and N7000 in the catalogs. There is a small 2-position toggle switch to the left of the HF control knob on the back of the low-frequency crossover. What does that do? What is signified by the B and R markings next to the phone jack inputs to the LF crossover?

One of the catalogs shows a cross-section cutaway of the crossover. I don't think that I'll like working in that space. What are the chances that the L-pads or pots are in usable condition? They do seem to crank smoothly.

The drivers are LE15A (for sure), and probably 2105 and 077.

So, what are good port dimensions for an LE15A in a 5 cu ft enclosure? If I port it, I should pull out all the stuffing and cover 3 of the walls with some kind of other deadening material, right?

When I look at the price lists, I see that LE15A was the most expensive woofer, so I'll guess that there is not much reason to look to replace it.


Thanks

There are a lot of people that know a lot more than I do here but, I did find that the LE-15A can be used in a closed cabinet. You only gave two dimensions for your speaker 19 3/4" H and 27 3/4" wide ?" deep

http://www.lansingheritage.org/images/jbl/specs/home-comp/le-bass/page1.jpg

The LE stands for linear efficiency. Designed for closed cabinets of 6 - 8 cubic feet internal volume.

http://www.lansingheritage.org/images/jbl/specs/home-comp/le-bass/page2.jpg

The LE15A delivers optimum results installed in a sealed cabinet of 6 - 8 cubic feet internal volume. No two dimensions may exceed a ratio of 3:1.

A photo would help a lot! When you post a question, page down to "additional Options" you will find "Attach Files". This way you can take a photo from your computer and include it in your post.:)

Ed

[Lucas Membrane]

There are a lot of people that know a lot more than I do here but, I did find that the LE-15A can be used in a closed cabinet. You only gave two dimensions for your speaker 19 3/4" H and 27 3/4" wide ?" deep

http://www.lansingheritage.org/images/jbl/specs/home-comp/le-bass/page1.jpg

The LE stands for linear efficiency. Designed for closed cabinets of 6 - 8 cubic feet internal volume.

http://www.lansingheritage.org/images/jbl/specs/home-comp/le-bass/page2.jpg

The LE15A delivers optimum results installed in a sealed cabinet of 6 - 8 cubic feet internal volume. No two dimensions may exceed a ratio of 3:1.
Ed

I'll see if I can get my wife to help with the photo when she has time. She is the only one about with a camera.

External dimensions are roughly 27.75 x 19.375 * 17.25. Allowing for 3/4-inch thickness, that gives a little under 5 cu ft (4.57?). I surely have no interest in making bigger cabinets for these, as they are already as large and heavy as I can possibly move about.

Anyone ever try an aperiodic vent with these woofers?

[grumpy]

if the front baffle is 3/4" thick, a 3.5" diameter hole might do the job
(yellow, closed 5ft3 box, white, ported 5ft3 box) ... I'd leave the stuffing
and look more closely at your crossovers (which may be entirely adequate).