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dig_dabeat
06-03-2003, 12:36 AM
I recently bought a D123A pair. I was expecting them to be the same as the 123, but discoverd that they were purely a bass driver. Nonethles, when I plugged them in, they sounded great. I am wondering if I can run them "full range" and just add a tweeter.
I have trued them in parrallel with somehigh frequency units, and the results are promising..
steve

Robh3606
06-03-2003, 06:13 AM
Yes you can that is how JBL ran them in the L88 L100 and 4311. Just add the tweeter of choice.

Rob:)

MikeM
06-03-2003, 08:10 AM
They will work pretty good and have great lowend. I bet you can get away with a crossover cap only and be fine. the crossover in the L100 is that simple. Enjoy. Heck I used a 2215 with a 2405 wih a 7k crossover works well

boputnam
06-03-2003, 08:29 AM
I don't have all my files with me, but the 123A was used in the L100, and I think the L88, but not in the 4311.

The L100 is/was a 3-way cabinet with the LE5-x midrange and LE20 (or later the LE25) tweeter.

The L88 is/was a 2-way cabinet that came with optional "M12 expansion kit" for fitting the cabinet with the LE5-x midrange.

The 4311 is/was a 3-way cabinet, and so far as I know used the 2213H woofer, LE5-x mid-range and the LE25 tweeter.

The 2-way configuration will certainly work but you might not have the imagining you want in the mid-bass - low hi-freq crossover range.

Heck - eBay yourself some LE5-x's and a 3-way network and go!

Also, be aware the 123A's are POSITIVE polarity (cone excursion OUT on positive signal) opposite almost every other JBL transducer!

boputnam
06-03-2003, 08:51 AM
Doh! I knew I was getting sucked into a 123A confusion and should trusted my instincts - "WAIT FOR YOUR FILES!"

Thanks, "Dr. Giskard"

4313B
06-03-2003, 08:53 AM
Hi guys,

The D123 is not a 123. It's the same driver as the old 2125 Pro model. You can go retro and pair it up with an LE20 and LX2 or with an 075 and N2400.

Here's the 2125:

http://www.lansingheritage.org/images/jbl/catalogs/1974-pro/page12.jpg

Here's the D123:

http://www.lansingheritage.org/images/jbl/catalogs/1976-comp/page3.jpg

T/S parameters for both are here:

http://www.jblproservice.com/pdf/Small%20Thiele%20Parameters/Thiele.pdf

4313B
06-03-2003, 09:35 AM
Ooops sorry Bo, deleted my post so I could expand on it properly :(

I really need to finish my matrix of home products just like the Pro stuff..... :(

i.e.
http://www.jblproservice.com/pdf/Systems%20Reference%20Charts/Studio%20Monitor%20Series.pdf

boputnam
06-03-2003, 09:44 AM
Funny you should say that - I've been compiling that exact same matrix myself, out of just this type of frustration! But, my resources are much more limited than yours are...

I'll be most interested in your completed product!

John Y.
06-03-2003, 10:45 AM
Hi dig_dabeat,

Giskard, as usual, is right on. The thing that was confusing to me was that you called the driver a D123A. The 123A series was used in the L88, L100, etc. The 123A had the same frame as a D123, but is strictly a LF unit, whereas the D123 (with bright aluminum dust cover) is usable up to above 2500 Hz with a LE20 or 075 (2402H) tweeter. I'm not sure it is adequate up to the 6500 Hz range for use with a 2405H in a two way, but I bet it is with a 2404H "baby cheeks" at 3000 Hz.

So, which is it? 123A or D123? Free air resonant frequency of the 123A is 25 Hz, compared to 45 Hz for the D123. The 123A would make for a better low end.

John

Mr. Widget
06-03-2003, 10:45 AM
Originally posted by dig_dabeat
I recently bought a D123A pair. I was expecting them to be the same as the 123, but discoverd that they were purely a bass driver. Nonethles, when I plugged them in, they sounded great. I am wondering if I can run them "full range" and just add a tweeter.
I have trued them in parrallel with somehigh frequency units, and the results are promising..
steve

The D123 was the woofer that JBL modified to create the 123A for the L100, 4310 etc., etc. It does not have the added aquaplas and therefore has a lighter cone that will be rather bass shy. As I recall it does produce fairly high frequencies that will allow you to create a two way, however it is very beamy and not real clean sounding in the upper midrange. For an inexpensive two way I agree with Giskard. Take a look in the library at the 60's era catalogs and see how JBL used the D123.

Have fun!

http://www.lansingheritage.org/html/jbl/catalogs/jbl-catl.htm

Robh3606
06-03-2003, 07:05 PM
To end all confusion is the cone white on the face?? Or dark??

Boputnam You have the watch those lists. The 4311 predates the ferrite conversion so the original driver was a 2213A not the H Take a look at the 4311 brochure in the library.

Rob:)

boputnam
06-03-2003, 08:26 PM
Ha! And, a great question!

At least in being wrong, I got the 2213 bit right :D

And I did, when getting home to my files, get my brain sorted out and noted the error. Doh!

Lesson #4311: when at work, keep the mind at work and await the more learned answers of those not distanced from their lists, or who just basically KNOW MORE than I do!

It's just SO DANG HARD when the day is wearing on to not at least take a little peak into The Forum.

Addiction takes on many forms (as do mid life crises!!!)...

Robh3606
06-03-2003, 08:40 PM
"It's just SO DANG HARD when the day is wearing on to not at least take a little peak into The Forum."

Yeah it sure is!!

Rob:)

GordonW
06-09-2003, 09:18 PM
Hey, this may be a "doh, everybody knows this already but me" thing...

... but does the 'D' in "D123", "D130", etc, stand for "Duralumin", as in the dustcap composition (ie aluminum)?

Regards,
Gordon.

Steve Schell
06-09-2003, 11:53 PM
Hi Gordon,

A perfectly good question. Duralumin is a good guess, as that is what the shiny dust domes are made from. My guess, though, is that the D just stands for "driver". In Jim Lansing's 1948 catalog, he used the D designation for every driver, including the D175 compression driver and the D130A woofer that used a paper dustcap.

Mr. Widget
06-10-2003, 12:08 AM
[i]My guess, though, is that the D just stands for "driver". In Jim Lansing's 1948 catalog, he used the D designation for every driver, including the D175 compression driver and the D130A woofer that used a paper dustcap. [/B]

Ok, but what about the 150-4C and the 375... well they did come along later, but then so did the D123 and the D208...

I'll put my money on D for driver and the the Lansing lack of consistency. Ask Bo about JBL's polarity conventions.:D :D

4313B
06-10-2003, 06:37 AM
"Ask Bo about JBL's polarity conventions."

The only errant driver I know of is the 123A-1 and that driver can be either. One thing is for sure, it's probably a good idea to run the battery test on any 123A's one comes across and intends to use.

Steve Schell
06-10-2003, 10:53 AM
Mr. Widget, you are correct that the 375 and 150-4C came along later, and the use of the "D" was inconsistent from then on. The D208, however, was an original Jim Lansing design and was being produced by 1948 or so. Hal Cox has told me that Jim Lansing designed the D208 to compete with the Altec 400 Dia-cone eight inch driver. Hal says that there was a lot of "buzz" at the AES meetings about the 400 being a very good driver for its size.

Jim Lansing may have had a hand in designing and tooling up to produce the 400 before he left Altec. The 400, 600 and 603 Dia-cone models all appeared about the same time, late 1945 or early 1946- about the time Lansing left Altec. The very idea of using an aluminum dustcap to extend highs may have been Lansing's. The term "Dia-cone" refers to the combination of a diaphragm and cone being used together in one unit.

I have an early Dia-cone in my collection; 603 serial #15. It has a red, white and blue label. It is still mounted to its original black 15" square baffle board, and the initials "JBL" are written on it in pencil. I have compared them to other examples we have of Jim Lansing's initials, and they appear to be genuine.