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Thread: JBL 4425 Questions : JBL 2416H vs. RAdian 1225-8

  1. #1
    Junior Member notengewirr's Avatar
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    JBL 4425 Questions : JBL 2416H vs. RAdian 1225-8

    Hi,
    i'm a german newbie here and since last week i own a very nice pair of JBL 4425.
    The speakers are in very good condition and the woofers are refoamed and measured (with data sheet) by a german professional:
    http://behringer-electric.de/
    He didn't recone because of the very good condition of the original Woofers.
    My 4425 came from a studio-basement only stored for custom replacing-requirement,so they are like NOS !

    Now i read about the replacing Radian 1225-8 drivers with aluminium diaphragm and Mylar surrounding.(cost 99€ + Back Plate)
    The original JBL 2416H is titanium dome with diamond surrounding structur...
    Ok there is no need for a replace ,but some people said the Radians are more "refined" sounding and have less distortion because of lower mass.

    Somebody compared ???
    Cheers
    notengewirr

  2. #2
    Senior Member Rudy Kleimann's Avatar
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    Radians are well-made alternatives

    The Radian diaphragms hold the promise of a smoother sound quality with the inherently better resonance-damping qualities of aluminum as compared to Ti, and the Mylar surrounds on the Radian avoids aluminum surrounds' inherent weakness of work-hardening from high-output flexing which led to cracking and diaphragm failure - the reason JBL switched from Al to Ti as a diaphragm material in the '70's.

    I just bought a pair of Radian 1225-8 for use in JBL 2426 drivers. I will be using them on 2344A horns, A/B comparing them directly against another pair of 2426 drivers and 2344A horns in my main home system with 2012H 10" mids in a small box atop JBL 4507 cabinets loaded with JBL 2035H or 2226H 15" woofers.

    The pair of 2426 drivers with Radian diaphragms were recently tested and tweaked at a fellow LHS member's "lab" with his TEF analyzer system and newly-completed Plane Wave Tube. The Radian diaphragm F.R. sweeps compare very favorably to my best performing factory Ti 8 ohm diaphragm on another JBL 2426 (actually a 2425HS on a threaded adaptor for 2426=2426).

    White: JBL Ti D8R2425
    Yellow: Radian 1225-8
    Magenta: Radian 1225-8
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    He did a little tweaking on one of the Radian-equipped drivers and got rid of that dip in the 5.5K to 7KHz area, but he hasn't had time to work on the other one yet.

    One of my JBL drivers came from ebay with an aftermarket Ti diaphragm (probably chinese Mfg.)
    Just to show what "cheap crap" gets you, he swept it on his PWT/TEF setup, and even after tweaking for over an hour, the best FR graph was deplorable!


    White: JBL Ti D8R2425 (same as in above graph)
    Yellow: Aftermaket Ti (likely Chinese knock-off) Positive marked with 1/4" round red sticker marked +
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    I need to come up with one more diaphragm for the project, but can't decide if I should get another JBL Ti diaphragm for stereo comparison listening, or another Radian for a L-C-R Home Theater setup, which is the end goal of the project...


    I will start a thread on the project and the listening tests when I get the drivers back and start on the project after the New Year.



    Quote Originally Posted by notengewirr View Post
    Hi,
    i'm a german newbie here and since last week i own a very nice pair of JBL 4425.
    The speakers are in very good condition and the woofers are refoamed and measured (with data sheet) by a german professional:
    http://behringer-electric.de/
    He didn't recone because of the very good condition of the original Woofers.
    My 4425 came from a studio-basement only stored for custom replacing-requirement,so they are like NOS !

    Now i read about the replacing Radian 1225-8 drivers with aluminium diaphragm and Mylar surrounding.(cost 99€ + Back Plate)
    The original JBL 2416H is titanium dome with diamond surrounding structur...
    Ok there is no need for a replace ,but some people said the Radians are more "refined" sounding and have less distortion because of lower mass.

    Somebody compared ???
    Cheers
    notengewirr

  3. #3
    Administrator Robh3606's Avatar
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    Well do you want 4425's or something else??

    Rob
    "I could be arguing in my spare time"

  4. #4
    Junior Member notengewirr's Avatar
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    today i received my new Radian 1225/8 and installed them with the 1225-C back cap quickly.

    very clean sounding with good transients & resolution
    i think they are a little bit smoother especially in the lower mid-range. Top end is similar the Ti's.

    I noticed there are holes instead of slots in my 2416 phase plugs. I only heard the plugs with slots are cheeper to produce.
    Is there a audible difference ?

    The Mylar surrounding looks like a simple plastic disc with eight holes in it.


    here are some pics.




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  5. #5
    Senior Member Rudy Kleimann's Avatar
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    2416 or 2415?

    As far as I know, that looks like a 2415 phase plug. I wonder, did the early model 4425's have 2415H drivers in them?

    JBL made a 2415H with that phase plug. All 7 of my 2416H drivers have the radial slit phase plugs.

    I have only seen pictures or heard about the 2415H phase plug with the holes. I posted the pics (from an ebay auction) here on another thread a few years ago, asking what they were. Some of the veterans here ID'd them as 2415 drivers with 2416H diaphragms installed.

    I recently received a NOS JBL D8R2415 diaphragm that appears to have a copper voice coil wire. JBL supersedes to the D8R2416 when ordering diaphragms for a 2415H. D8R2416 diaphragms use aluminum voice coil wire.

    JBL also made a 2416H AND a 2416H-1, but I am not certain of the differences. I once heard that the 2416H-1 had ferrofluid, but that is wrong AFAIK. I have never seen ferrofluid in any JBL drivers, including the ones I have that the diaphragms are labelled 2416H-1.

    I also own 4 2417H drivers, and it's phase plug has radial slits. However, the dome of the phase plug is not as high as the previous models, and the 2417 diaphragm is built to match- it will not fit on 2416H drivers because the phase plug of the 2416 sits too high.

    I once mounted a bad 2425 diaphragm on top of a 2416 and pushed down on the dome to see how close it is to the phase plug, and it is very close (as it should be).

    When I mounted the bad 2425 diaphragm to the 2417H and pushed on it, the space between the diaphragm and phase plug was MUCH greater, perhaps 3-4 times as much as on the 2416 (definitely not right).

    Those "aftermarket" diaphragms that claim to fit 2415, 2416, and 2417 drivers, are correct only in that they don't hit the phase plug, but that is it. Besides, the 2417 diaphragm is thinner than the 2416 and the surround is different too. I can't imagine an aftermarket diaphragm sounding anywhere near right in a 2417 -but they "fit".

  6. #6
    Junior Member notengewirr's Avatar
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    Hi Rudy,

    interesting !

    Speak of the devil and the devil shows up!
    Do we all have 2415s


    My 4425 are from 1988 and really originally fitted ,nothing was changed.
    Only a few weeks ago,my best friend bought another pair of 4425.He screwed open his 4425 with same result.
    Phaseplug with holes ,like mine.Exactly the same.His 4425 are stamped 1989.
    Both have the same original titanium D8R2416 fitted.I'm not 100% sure but the coils looks like alu.
    One of his diaphragms doesn't fit exactly on the driver-plate.There was a little space and he had problems to center the diaphragm exactly.
    We noticed this before,because the Horn produced a "farting" sound by playing Bass-Sinus signals.These farting sounds comes out of the Horn-Front.So he covered the little hole on the back site of the diaphragm.The noise has gone.
    In two days he will receive his Radians,then i will check his Drivers again...

    Edit: The difference between 2415H & 2416H is =The 2415 have a higher DCR (4.5 vs 3.2) and the holes.
    Ok, then JBL must have matched the crossovers for these (early 4425) Versions
    here is a pic from my crossover:

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    Last edited by notengewirr; 01-05-2012 at 12:33 PM. Reason: Edit

  7. #7
    Senior Member Rudy Kleimann's Avatar
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    Good question

    Speak of the devil? Me?


    The 4425 was last produced in 2000 and used a 2416H-1 according to JBL service documentation. Perhaps the early production models used a 2416H (before the -1 variant). The 4425 Brochure posted on jblpro.com is copyyrighted 7/93.

    That being said, I suppose it is possible that the model progression could be as follows:

    2415H: round holes through phase plug, copper coil on diaphragm

    2416H: round holes through phase plug, aluminum coil on diaphragm

    2416H-1: annular slits into exponential flare phase plug a la 242x drivers, aluminum coil on diaphragm.

    This is only my educated guess and not to be construed as fact.

    Considering that your 4425's (and your friends'?) are equipped with the round hole phase plug, who knows?


    I can't speak for the dates or original diaphragms on my drivers, as all of mine were bought used. But I know all 7 drivers have the phase plug with annular slits. 4 of them came in MR8xx cabinets. JBL Pro Service docs list 2416H-1 used in all MR8xx models and last produced in 1996. The MR800 Brochure is copyright date 5/91.

    Thinking about it, I need to clarify that the drivers I saw on ebay a few years ago were listed as 2416H, but as we all know, the driver itself isn't marked -only the diaphragm. in fact, the only way I was sure about the 2417 vs. 2416 drivers was via the diaphragm fit/phase plug clearance test method I used with old diaphragms.
    Last edited by Rudy Kleimann; 01-05-2012 at 01:24 PM. Reason: Restructured post for clarity

  8. #8
    Senior Member Rudy Kleimann's Avatar
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    I recall noticing the different DCR on my 2415 diaphragm compared to 2416. What the actual impedance is over the frequency range is another matter.

    You are referring to the tiny vent hole on the diaphragm assembly/cover, correct? I too have wondered about that. I suppose that the LF driver could pressure up the cabinet high enough and long enough at very low frequencies to modulate the HF diaphragm through that vent hole. the 4425 cabinet is tuned to 34HZ.

    Quote Originally Posted by notengewirr View Post
    Hi Rudy,

    interesting !

    Speak of the devil and the devil shows up!
    Do we all have 2415s


    My 4425 are from 1988 and really originally fitted ,nothing was changed.
    Only a few weeks ago,my best friend bought another pair of 4425.He screwed open his 4425 with same result.
    Phaseplug with holes ,like mine.Exactly the same.His 4425 are stamped 1989.
    Both have the same original titanium D8R2416 fitted.I'm not 100% sure but the coils looks like alu.
    One of his diaphragms doesn't fit exactly on the driver-plate.There was a little space and he had problems to center the diaphragm exactly.
    We noticed this before,because the Horn produced a "farting" sound by playing Bass-Sinus signals.These farting sounds comes out of the Horn-Front.So he covered the little hole on the back site of the diaphragm.The noise has gone.
    In two days he will receive his Radians,then i will check his Drivers again...

    Edit: The difference between 2415H & 2416H is =The 2415 have a higher DCR (4.5 vs 3.2) and the holes.
    Ok, then JBL must have matched the crossovers for these (early 4425) Versions
    here is a pic from my crossover:

    Attachment 54337

  9. #9
    Junior Member notengewirr's Avatar
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    Ok, thank you Rudy ,

    i think you're right.I measured my original JBL Ti 2416H diaphragm with 3,2 DC. The radian 1225/8 is the same,so the replacement on my 2416H/2415H will be right.It fits perfectly,so i don't worry about.
    This weekend i will measure the DC of my friend Driver too.

    ...now i have to listen my new Radians.... ...the three-dimensionality ...sounds...WOW.....

    cheers

    Andreas

  10. #10
    Junior Member notengewirr's Avatar
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    Vent Hole

    Quote Originally Posted by Rudy Kleimann View Post

    You are referring to the tiny vent hole on the diaphragm assembly/cover, correct?
    correct!

    i guess the little vent hole prevent a vacuum behind the diaphragms , or perhaps compensate atmospheric pressure...

    The Radian diaphragms don't need this hole ,because the Mylar surround is perforated.So the Air can flow behind the diaphragms.

  11. #11
    Senior Member Guido's Avatar
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    2415

    Those drivers with holes are 2415 drivers. A bit less top end than the later 2416 drivers with slit phase plug.
    I saw a lot of 2415 coming out of 4425 cabinets. Seems that they where used by JBL in earlier 4435 models.

    I frequently recommend the alumnium replacements from Radian. They really sound smoother than the Ti's. Well someday we will have Beryllium replacements....

    Notengewirr, are you satisfied with the refoam

    Happy new year to all,
    Guido
    BLS Reference on Passlabs XA 30.5 + Everest DD66000 clone on Pass XA 100.5

  12. #12
    Obviously... not a golfer grumpy's Avatar
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    Seems that they where used by JBL in earlier 4435 models
    ...and by 4435 (early versions of 4430/5 used a 2421A), you mean 4425?
    It's uh... uh... it's down there somewhere, let me take another look...

  13. #13
    Junior Member notengewirr's Avatar
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    Hi, today i swapped back to my original titanium D8R2416... Hm...with some music (i prefer electronic music) they sound more forward, more "aggressive"( i think it's this unique JBL Professional Sound)
    With pop music & voices the Radians are slight better...more HiFi-like...
    puh ...critical decision...and i simply can't decide which of them sounds better...

    @ Guido

    yes! the refoaming (http://behringer-electric.de) is commendable ! Neat Work !

    here are pics of my refoamed 2214H


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  14. #14
    Senior Member Guido's Avatar
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    Quote Originally Posted by grumpy View Post
    ...and by 4435 (early versions of 4430/5 used a 2421A), you mean 4425?
    Ummm... You're right

    It's because I always dream of my 4435
    BLS Reference on Passlabs XA 30.5 + Everest DD66000 clone on Pass XA 100.5

  15. #15
    Senior Member Rudy Kleimann's Avatar
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    Vented surround?

    I didn't know the Radian 1225's had holes in the surround! Perhaps it is for equalizing pressure, as you guessed. Makes sense. Would also prevent the woofer and cabinet from modulating the diaphragm like it was doing in your case. That farting sound you heard was probably the diaphragm crashing into the phase plug. Not good...

    I haven't actually seen my pair of Radians 1225's yet, as they are with a fellow LHS member who received, installed, and ran F.R. sweeps on them for me (many thanks, B!) I'll have to take a look for myself when they come home.

    My LHS friend and I have been discussing the 4" diaphragm ferrite drivers having reliefs cut into the top plate that allow air to travel from one side of the diaphragm to the other. We were a bit puzzled by its' purpose... I joked about it being a tuned port for the rear chamber .

    Can you post a front, side, and rear view pic of the Radian covers you bought for use on the 2415/16? Does it have a breather hole in it?

    Quote Originally Posted by notengewirr View Post
    correct!

    i guess the little vent hole prevent a vacuum behind the diaphragms , or perhaps compensate atmospheric pressure...

    The Radian diaphragms don't need this hole ,because the Mylar surround is perforated.So the Air can flow behind the diaphragms.

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