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Thread: 12-inch Transducer Thread

  1. #1
    Senior Seņor boputnam's Avatar
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    12-inch Transducer Thread

    Notwithstanding that 12-inch transducers have as many proponents as opponents, I'm looking for some experience here.

    1) Why no LE12?

    2) What are the specs of each the 123A-1 (alnico, positive) and 2213H (ferrite, negative) - and why were the manufactured at around the same time for nearly identical applications?

    3) Is the 2202 the flattest response 12-inch transducer JBL made?

    4) other thoughts/comments?

    Thanks.
    bo

    "Indeed, not!!"

  2. #2
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    "1) Why no LE12?"

    Because JBL twelves suck and there was no way they were going to label any of them "Linear Efficiency".

    JK! The LE12C was a composite transducer consisting of the D123/123A basket and the LE20 HF.

    http://www.lansingheritage.org/html/.../1976-comp.htm


    "2) What are the specs of each the 123A-1 (alnico, positive) and 2213H (ferrite, negative) - and why were the manufactured at around the same time for nearly identical applications?"

    One is for Pro and one is for Home.

    The TS parameters are here

    http://www.jblproservice.com/pdf/Sma...ers/Thiele.pdf

    "3) Is the 2202 the flattest response 12-inch transducer JBL made?"

    Oh no. That distinction would quite likely go to the 128H/128H-1.
    Last edited by 4313B; 04-22-2003 at 08:33 PM.

  3. #3
    Administrator Robh3606's Avatar
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    The 123-a was the original alnico the 2213h was a ferrite replacement when they changed over.

    I have used 123A, 122A and 128h-1. The 128h-1 is really a nice smooth sounding woofer. I like the 122a's too but don't use them above 300hz.

    Hey Giskard you wouldn't have T/S on the 129H??? JBL came up short for help.

    Thanks

  4. #4
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    "Hey Giskard you wouldn't have T/S on the 129H?"

    Nope
    Sorry

  5. #5
    Senior Seņor boputnam's Avatar
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    Thanks, Giskard and Robh.

    I knew about the LE12C but don't favor composite transducers. Maybe I'm wrong there...?

    It's really odd that the 123-A at the time it came out was positive - most else then was negative. It must have been a confusing time aroung the water cooler at LBJ... Whoops - JBL.

    "Negative is Good"
    bo

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  6. #6
    Senior Seņor boputnam's Avatar
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    Another kick at the can...

    The Thiele specs on the 123-A and 2213H are virtually identical (I've looked at this before, equally mystified on distinction). The only significant variance I can see is the Pe - with the 2213H having higher peak power handling.

    Am I overlooking something, or is there a notable difference in their response curves? Is the 123-A noticeably "better" at all?

    Sorry to beat this to death...
    bo

    "Indeed, not!!"

  7. #7
    Administrator Robh3606's Avatar
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    "The Thiele specs on the 123-A and 2213H are virtually identical"

    They are supposed to be the H was the ferrite replacement when Alnico was no longer available.

    Rob

  8. #8
    Senior Seņor boputnam's Avatar
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    I wondered that, thanks.

    So, give me the brief "brief" on the alnico-ferrite argument (which goes on endlessly, I know). Was ferrite phased in because of the demagetization alnico suffered, or is that too another "myth".

    And, having both on the bench, which would you choose?
    bo

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  9. #9
    Administrator Robh3606's Avatar
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    OK

    There was a war in Africa so Cobalt was no longer commercially available which is a major component in the Aluminum Nickel Cobalt/ Alnico magnets. So they had no choice but to convert to ferrite.

    Which one to choose??? I use both and they work great at home. If I was a pro I would go Ferrite because of the demag and power compression issues with alnico.

    Rob

  10. #10
    Senior Seņor boputnam's Avatar
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    Many thanks...

    If true (I trust it is, but wow..), it makes more than perfect sense.

    I'm an economic geologist (metals), and Zaire (now Democratic Republic of Congo) seemingly is god's joke - place enormous mineral riches (diamonds, copper, cobalt, gold and zinc) of unmatched quality and in concentrations nowhere else found on the planet, and serially inhabit the region with genocidal tribes that use the wealth as weapons - to fund their terrorist campaigns. This led to the recent efforts by DeBeers to laser-label their South African, Australian and Canadian stones to distinguish them from blood diamonds from DRC and Sierra Leone.

    Cobalt has limited economic concentrations outside Russia, and Australia. The deposits in Washington and Idaho states (NJ too...) are sub-grade and cannot be sensibly developed.

    As with the beautiful blue, cobalt glass, so went AlNiCo magets...

    Thanks very much for the history, and opinions.

    Still learning,
    bo

    "Indeed, not!!"

  11. #11
    Administrator Mr. Widget's Avatar
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    The war bit is true. At first as the supplies of cobalt started to become scarce all alnico speaker's prices went up, then the various manufacturers that were still using alnico realized they couldn't continue increasing prices endlessly so they began redesigning the driver magnet assemblies.

    On some speakers I feel there is no difference between the alnico and ferrite versions. On others however there are sonic differences. The differences can be both in type and amount of distortion as well as frequency response. One of the considerations is that before JBL changed it's woofer magnet assemblies from alnico to ferrite they had quite a few distinctly different variations. For economic reasons with the early ferrite models there were many compromises made to reduce the number of necessary variations. For this reason I am not as fond of the very first round of ferrites as with the later models. I feel that the first round introduced in 1980 when all of the previous models 2231A, 2215A/B etc. were reintroduced as 2231H, 2215H the designs were not as developed as the later models with their subsequent improvements. I feel that JBL learned their lesson on the woofers and so when they finally realized that they would have to switch out the compression drivers they completely redesigned all of them except the ring radiators. All of the new drivers had completely new designations and were ground up new designs.

    For the most part though the alnico issue is more lore than fact.

  12. #12
    Senior Seņor boputnam's Avatar
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    Beach Chalet for a Heineken, on me...

    Thanks, Mr. Widget (you too, Robh). Filled a gaping area of my knowledge of JBL lore.

    Still learning,
    bo

    "Indeed, not!!"

  13. #13
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    129H follow-up

    "Hey Giskard you wouldn't have T/S on the 129H?"

    Same T/S parameters as for the 122A

  14. #14
    Administrator Robh3606's Avatar
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    Thanks Rob

    I was wondring about that. The L65C is the only place I have ever seen the 129H??? It has to have been used in more places than the Jubal. It shows up in the Pro driver list???? It looks exactly like a 122a, cone the same diameter and lasaplas on the back on the cone, same frame. The 128H-1 is a smaller coned driver in the same frame. The one I have has a name plate and serial number. They ever sell them as a components?? Same label as the 1979 component catalog drivers.

    Rob

  15. #15
    Tom Loizeaux
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    I think one of the reasons the JBL 12s aren't that popular is that the 15" versions have so much more thump to them. When you've heard a 2235 growl at 35Hz it's hard to be satisfied with a 2213. I added a JBL PB12 subwoofer to my pair of 4312As and the low end is now very respectable!
    I always wondered why JBL didn't put out a speaker like the 4312 with dual 2213s in it and make it a tower design.
    I think low end would be improved, SPL ability increased and distortion noticably decreased.

    Tom
    Last edited by Tom Loizeaux; 06-07-2003 at 08:50 AM.

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