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View Full Version : Crossover for LE 15A and 15B



banker80
05-03-2004, 09:03 AM
Could some one explain the characterisics of the jbl crossovers for the LE 15A and LE 15B. Early literature looks like the LE15A was a 16 ohm LF woofer and was coupled with an 8ohm LE 85.

The LE 15B is an 8 ohm LF woofer. Which one compliments the LE 85 8 ohm driver. Then, what vintage jbl crossover do I use with it?

boputnam
05-03-2004, 09:13 AM
You might start, here...

http://www.lansingheritage.org/images/jbl/catalogs/1976-comp/page7.jpg

and the following page show the LE15A is 8ohm.
http://www.lansingheritage.org/images/jbl/catalogs/1976-comp/page8.jpg

I don't know anything about the LE15B (maybe Giskard, or others, do...).

4313B
05-03-2004, 09:39 AM
Originally posted by boputnam
I don't know anything about the LE15B (maybe Giskard, or others, do...). From one of my previous posts -

Here are the various impedance specs for the various transducers:

LE15B "8 ohms" with DCR range of 3.1 to 3.9 ohms (C8RLE15B)
2215 "8 ohms" with DCR range of 5.2 to 6.2 ohms (C8R2215)
2215A "8 ohms" with DCR range of 5.2 to 6.2 ohms (C8R2215)
LE15 "16 ohms" with DCR range of 7.6 to 9.2 ohms C16R2215)
LE15A "16 ohms" with DCR range of 7.6 to 9.2 ohms (C16R2215)
2215B "16 ohms" with DCR range of 7.6 to 9.2 ohms (C16R2215)
LE15H "8 ohms" with DCR range of 8.0 to 9.6 ohms (C8RLE15H)
2215H "8 ohms" with DCR range of 8.0 to 9.6 ohms (C8RLE15H)

This is what it is, regardless of what is stamped on the basket. JBL could technically get away with stamping the "16 ohm" LE15A as "8 ohms" because Zmin occurs at roughly 10 ohms. That's why you will notice many of the LE15A networks use 10 ohm conjugates. Like the "12 ohm" 077/2405 that turns up stamped as "8 ohm" or "16 ohm", the LE15A is really a "10 ohm" transducer. Bottom line is, it all depends on where in it's range you're going to employ it and whether or not you use a conjugate or if you are going to pop a 20 ohm resistor across it like is so often done with the 077/2405.

4313B
05-03-2004, 09:46 AM
Ooops, missed this - " Which one compliments the LE 85 8 ohm driver."

The LE85 is a "16 ohm" driver regardless of what is stamped on the back. (Rumor has it that it was considered "12 ohms" for load purposes but whatever...)

Anyway, from a previous post -

Re: 2420 voice coil DC resistance?
Here it is again:

D16R2420 5.9 - 7.0 ohms

D8R2421 2.9 - 3.5 ohms
D16R2421 5.9 - 7.0 ohms

D8R2425 2.9 - 3.5 ohms
D16R2425 5.9 - 7.0 ohms


The LE85 used the D16R2420 diaphragm. A 2420 is an LE85 in Pro attire.

It should be noted that I can no longer remember whether it was the 077/2405 that was considered a "10 ohm load" or the LE85/2420. One was a "10 ohm load" and one was a "12 ohm load". Anyway, who cares at this point. That was over 30 years ago... just measure them to figure it out again. :p

Guenter
05-03-2004, 06:23 PM
Giskard, intersting post re the woofers and their impedances.

Well, I just don't know what to say re the woofers except that I just went into the closet and checked my LE15B - labeled as such on the aluminum foil on the back of the magnet. Again, I have the 'B' version of the LE15. It is stamped '16' ohm and when I measured the DC resistance just now it is 14.2 ohm with a few tenths of an ohm variation between each of the four LE15B's that I have.

- can you suggest an explanation??

4313B
05-03-2004, 06:55 PM
"- can you suggest an explanation??"

Yeah, they don't have LE15B cone assemblies in them.

OR

JBL documentation is notoriously erroneous.

JBL 15" drivers that could have that high of a DCR:
D130F-6
D140F-6
D140R-18
K140-16
K145-16
E130-16
E140-16
E145-16
130B
2205B
2205J
2220B
2220J
2225J
2230B

I guess banker80 will just have to measure the DCR's on his drivers.

Guenter
05-05-2004, 05:22 PM
many thanks. Yes, it likely was reconed somewhat differently in the factory. I looked at the drivers again and I was somewhat wrong. On the foil back it has in black 'LE15A' and then after the 'A' it has a 'B' apperently 'punched' on giving an indentation of the foil. On the back of the cone there is has a '2153' along
with a hand written ibn white, 'B Special'.

So, apperently something 'one of' by the JBL factory. Care to guess exactly what I've got? Is it a LE15A reconed differently? or is it a LE15B??

- thanks and best regards, Guenter

4313B
05-05-2004, 05:30 PM
Sounds like B stock LE15A's reconed special for someone.

Guenter
05-07-2004, 05:04 AM
Giskard, thanks again for your comments. However, I admit I don't understand what you mean. Are you saying that the drivers are genuine LE15A's with different cones? the drivers were initially used 2 in parallel per speaker. I imagine the 'true' 16 ohm impedance allowed for the continued use of the LX5 xover network when paralleling two drivers.

Seems old age is really setting in with me. Can't even remember #'s on the way from the basement to the computer.
The Number on the cone is actually '21513' does it have any obvious relevance at all?

- thanks, regards

4313B
05-07-2004, 05:43 AM
"Are you saying that the drivers are genuine LE15A's with different cones?"

It sounds like your four LE15A baskets have a different cone assembly in them. Where did they come from? You say they were wired in parallel and hooked up to an LX5?

"I imagine the 'true' 16 ohm impedance allowed for the continued use of the LX5 xover network when paralleling two drivers."

Maybe. The LX5 low pass is "looking" for a 10 ohm load at crossover.

Guenter
05-08-2004, 05:54 PM
Originally posted by Giskard


It sounds like your four LE15A baskets have a different cone assembly in them. Where did they come from? You say they were wired in parallel and hooked up to an LX5?

Some fellow in the late 60's or early 70's lost his Sovereign system in a divorce and decided to have one a bit better by implementing 2 woofers and 2 passives per side, all else being just like the Sovereign (S8R) He sourced these LE15A-'B' drivers
from a local dealer who presumable ordered them directly from JBL. So, yes, these drivers were connected in parallel to an LX5 network, it used two pleated surround passives (I always thought that passives should be at least as if not more flexible than the active driver). As well, interestingly, the builder of these cabinets put a circular diffraction lens (as in 175 'potato masher') in front of the 075 tweeter.....didn't think that would do all that much, but one never knows.

Maybe. The LX5 low pass is "looking" for a 10 ohm load at crossover. [/B] Sure, the LX5 xover network is expecting a single LE15A type speaker so they doubled the impedence of the driver coil. Confusing to me is if they used an LE15B basket and then reconed with the Lansalloy type cone (I believe the LE15B's used a pleated surround) with a 16 ohm coil, OR if the baskets are from an LE15A. any further ideas??

best regards

Guenter
05-08-2004, 05:59 PM
Originally posted by Giskard


It sounds like your four LE15A baskets have a different cone assembly in them. Where did they come from? You say they were wired in parallel and hooked up to an LX5?


Some fellow in the late 60's or early 70's lost his Sovereign system in a divorce and decided to have one a bit better by implementing 2 woofers and 2 passives per side, all else being just like the Sovereign (S8R) He sourced these LE15A-'B' drivers
from a local dealer who presumable ordered them directly from JBL. So, yes, these drivers were connected in parallel to an LX5 network, it used two pleated surround passives (I always thought that passives should be at least as if not more flexible than the active driver). As well, interestingly, the builder of these cabinets put a circular diffraction lens (as in 175 'potato masher') in front of the 075 tweeter.....didn't think that would do all that much, but one never knows.


Maybe. The LX5 low pass is "looking" for a 10 ohm load at crossover. [/B] Sure, the LX5 xover network is expecting a single LE15A type speaker so they doubled the impedence of the driver coil. Confusing to me is if they used an LE15B basket and then reconed with the Lansalloy type cone (I believe the LE15B's used a pleated surround) with a 16 ohm coil, OR if the baskets are from an LE15A. any further ideas??

best regards