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Thread: Replacement diaphragm for 2421A?

  1. #1
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    Replacement diaphragm for 2421A?

    Hello everyone,

    while surfing through the offers of a well known German musical instrument supplier I've found a genuine JBL D8R2425 diaphragm as well as a Radian 1225-8. They call € 189 for the JBL and € 99 for the Radian. Should I ever encounter the need of new daphragms in my 2421A's, would they fit? At a visual inspection the look very similar to the 2421's at least. And what's the difference between the JBL and the Radian diaphragms? Can the Radians compete with the JBL's that almost cost double the money?

    Best regards!

  2. #2
    Senior Member edgewound's Avatar
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    Quote Originally Posted by Kay Pirinha View Post
    Hello everyone,

    while surfing through the offers of a well known German musical instrument supplier I've found a genuine JBL D8R2425 diaphragm as well as a Radian 1225-8. They call € 189 for the JBL and € 99 for the Radian. Should I ever encounter the need of new daphragms in my 2421A's, would they fit? At a visual inspection the look very similar to the 2421's at least. And what's the difference between the JBL and the Radian diaphragms? Can the Radians compete with the JBL's that almost cost double the money?

    Best regards!
    The JBL titanium driver is more durable for live sound, the Radian 1225-8/1225-16 is a drop-in replacement and simply sounds better for playback monitors in the studio of hi-fi.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Thanks a lot, Edgewound!

    Can I derive from your statement that these 2425 replacement diaphragms will both also fit into 2421 cores?

    Best regards!

  4. #4
    Senior Member edgewound's Avatar
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    Quote Originally Posted by Kay Pirinha View Post
    Thanks a lot, Edgewound!

    Can I derive from your statement that these 2425 replacement diaphragms will both also fit into 2421 cores?

    Best regards!
    Yes! and Thank you!

    I just did this for a customer with a pair of 4320 Studio Monitors. Resuspended a pair of 2215B with new spider and surround, Full Service Teardown/Cleaning/Recharge of motors, adjust the moving mass to within 5% of Engineering Spec. Cleaned up a pair of 2420 and recharged the magnets, swapped out the D16R2425 with Radian 1225-16.

    The customer is a husband and wife musician team that said they now hear details and clarity they never heard before with the new Radian diaphragms. She's a violonist and was especially impressed with the fidelity and non fatiguing nature of the Radian diaphragms. Their associates that came into listen noticed the improvements as well.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

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    Thank you, that's amazing! So I tend to give these Radians a try and throw it into my 2421's before installing these in my 4430 projects.

    Best regards!

  6. #6
    Senior Member BMWCCA's Avatar
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    Would the same be true for the 2425J in my 4345 clones? One of my stay-at-home-COVID-19 projects is to remove and examine those drivers in my system—if they ever come to their senses and figure out that car sales shouldn't be essential!

    Thanks!
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Administrator Mr. Widget's Avatar
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    Quote Originally Posted by BMWCCA View Post
    Would the same be true for the 2425J in my 4345 clones? One of my stay-at-home-COVID-19 projects is to remove and examine those drivers in my system—if they ever come to their senses and figure out that car sales shouldn't be essential!
    I can’t speak to the Radian 1225-8, but based on Edgewound’s recommendation, I would give them a go. The JBL 2425/26 titanium drivers are quite harsh in my opinion, especially when the volume is turned up.

    Regarding stay at home and “essential” activities, it will be very interesting to see how this plays out. Here in the SF Bay Area we have been shut down since March 17th. Along with most everyone else, all car dealerships are shut down, but their service departments are open on a limited basis. To make sure people can stay 6’-10’ apart, grocery stores limit the number of people who can enter resulting in long lines of well spaced people in their parking lots. People here are taking this very seriously. When we eventually get the necessary testing capability in place and return to our new normal, we will see if these measures were effective.


    Widget

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    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Mr. Widget View Post
    I can’t speak to the Radian 1225-8, but based on Edgewound’s recommendation, I would give them a go. The JBL 2425/26 titanium drivers are quite harsh in my opinion, especially when the volume is turned up.

    Regarding stay at home and “essential” activities, it will be very interesting to see how this plays out. Here in the SF Bay Area we have been shut down since March 17th. Along with most everyone else, all car dealerships are shut down, but their service departments are open on a limited basis. To make sure people can stay 6’-10’ apart, grocery stores limit the number of people who can enter resulting in long lines of well spaced people in their parking lots. People here are taking this very seriously. When we eventually get the necessary testing capability in place and return to our new normal, we will see if these measures were effective.
    Thanks for the reply. One of my daughters lives in LA and the other in NJ but worked in NYC. Here in Central Virginia I don't think the general public is taking the "suggested" order seriously enough. And the car dealers are a powerful lobby nationwide as they assume that their sales departments are somehow "essential". My pet rant is that unless the law shuts us down, they don't have to pay us anything for endangering ourselves by coming to work unless we earn commission on a sale, which is a bit problematic since the Governor says "stay at home". And yet people still go car shopping!

    Rant off!

    I may give the Radians a try but first I'll swap or disassemble the drivers to see why one isn't as strong as the other.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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    Quote Originally Posted by BMWCCA View Post
    I may give the Radians a try but first I'll swap or disassemble the drivers to see why one isn't as strong as the other.
    Try swapping the drivers between speakers and see if the problem stays with the driver.

    See what the DCR measures.
    How old are the drivers, the foam may have rotted and is stuck all over the diaphragm.
    Do you have a way to directly tone sweep the drivers as a test.

    The Nomex voice formers have been known to bubble/disform even if the driver was never driven hard, I had one do that and it was almost stuck in the gap. That was in a stage monitor but the voice coil and diaphragm showed no signs at all of any damage.

  10. #10
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by Mike Caldwell View Post
    Try swapping the drivers between speakers and see if the problem stays with the driver.

    See what the DCR measures.
    How old are the drivers, the foam may have rotted and is stuck all over the diaphragm.
    Do you have a way to directly tone sweep the drivers as a test.

    The Nomex voice formers have been known to bubble/disform even if the driver was never driven hard, I had one do that and it was almost stuck in the gap. That was in a stage monitor but the voice coil and diaphragm showed no signs at all of any damage.
    Thanks, that is part of the plan. Right now I'm being called back to work as "essential" so no telling when I'll have the time again. Perhaps from my hospital bed? Something to do while I'm on a ventilator? Y'all be safe out there.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  11. #11
    Senior Member edgewound's Avatar
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    Quote Originally Posted by BMWCCA View Post
    I may give the Radians a try but first I'll swap or disassemble the drivers to see why one isn't as strong as the other.
    First of all....stay safe.

    Have you checked the L-pads for wear on the element?

    Mike Caldwell has a point about the foam pads falling apart inside and the condition of the voice coils.

    And...depending on how old the drivers are, a thorough cleaning and magnet recharge does wonders for AlNiCo drivers.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

  12. #12
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by edgewound View Post
    First of all....stay safe.

    Have you checked the L-pads for wear on the element?

    Mike Caldwell has a point about the foam pads falling apart inside and the condition of the voice coils.

    And...depending on how old the drivers are, a thorough cleaning and magnet recharge does wonders for AlNiCo drivers.
    Thanks. I thought these were all ferrite drivers. I intend to swap L—R first but no indication that the L-pad is at fault. If tests still point to just one driver, I'll disassemble it to see if it's a mechanical issue like foam plug or other contamination. If not, I'll probably do Radians in both.
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

  13. #13
    Senior Member edgewound's Avatar
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    Quote Originally Posted by BMWCCA View Post
    Thanks. I thought these were all ferrite drivers. I intend to swap L—R first but no indication that the L-pad is at fault. If tests still point to just one driver, I'll disassemble it to see if it's a mechanical issue like foam plug or other contamination. If not, I'll probably do Radians in both.
    Ah yes. Your 2425 ferrite. My bad. 2420/21 AlNiCo.
    Edgewound...JBL Pro Authorized...since 1988
    Upland Loudspeaker Service, Upland, CA

  14. #14
    Senior Member BMWCCA's Avatar
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    Quote Originally Posted by edgewound View Post
    Ah yes. Your 2425 ferrite. My bad. 2420/21 AlNiCo.
    We still love you!
    ". . . as you have no doubt noticed, no one told the 4345 that it can't work correctly so it does anyway."—Greg Timbers

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