Info on "SL" diaphragms needed

[sebackman]

Help on SL diaphragms needed.

JBL lists three different ”SL” diaphragms now, all with different MSRP’s, in the “what-goes-into” list.
http://www.jblproservice.com/pdf/Goes%20Into%20List/Goes%20Into%20List.pdf

D8R2450SL
D8R2450SL $264.00 2450SL (74114X)

D8R2452-SL
D8R2452-SL $234.00 2452H-SL (352328-003X)

D16R2451SL
D16R2450 $216.00 2450J, 2446J, 2447J, 2451J

As all these are completely interchangeable and would work in all drivers I would much appreciate if someone can tell me the difference (except for the obvious impedance difference) between these diaphragms, if any? And why are JBL not listing them with the same list of drivers they fit and perform in all motors?

All help appreciated

Kind regards
//RoB

[grumpy]

There have been several long threads on this topic...

Briefly, my recollection is that the 2452-specific unit has external
terminals that screw into what is essentially the same diaphragm frame as the rest
(vs. the others using screws/wires/lugs to make the internal connection).

If you have extra screws or terminals the distinction is fairly moot
(or I'm remembering it all wrong )... I think they're all smooth (no ribs).

Might be worth finding the thread with pics to verify.

[sebackman]

Hi,

Thank you.

You are off course right, the 2452 has different terminals. I should have spotted that. Sorry.

-So that narrows the comp down to 2450SL and 2451SL.

They are all smooth from the pictures I have seen but is there any sonic difference? Why does JBL not list them as compatible with all drivers and only make the distinction on impedance? Or are they indeed different, giving different sonic results dependant on what motor they go into? They are fairly expensive so a I would like to get some more meat on the bones before taking the plunge. I have the 2451 drivers in a home cinema system.

Any clues?

Best regards
//RoB

[subwoof]

this info is on multiple threads....

2450SL has a smooth dome ( without coating it is a 2445 )
2451SL has a ribbed dome ( without coating it is a 2450 )

of course to make it even MORE confusing, the dia used in the last version of the DMS monitor and HLA systems was the 2450SL-a which has a coated, ribbed diaphram.

There are OTHERS that have different combinations / model numbers ( like the 475Nd ) and are used in the ( not available to us ) high end systems....

in general, ribs make it less resonant for high SPL but ( to some ) color the response a little.

sub

[sebackman]

Hi Sub and others,

Nothing is ever simple, is it?

DMS1 uses the 1,5" 2332 horn (which i'm also using with the 2451) so I figured that the driver could not be the 2450 since that is a 2" driver. When looking at the JBL exploded view it says 2450SL-A and describes it as a 1,5" driver. It also looks like the 2451 not the 2450…
What? The JBL "goes into list" does not list a 2450-A motor at all!

What is the difference between 2450SL-A and 2451, if any?? Is the 2450SL dia for the 2" or the 1.5" driver? Is there any sonic difference? Why have different part no's if the motors are the same.

Has JBL ever made 2” SL drivers or are all 1,5” exit motors?

If they never made a 2” SL driver maybe the only difference between the D8R2450SL and the D16R2451SL is the impedance because the first dia is really made for the 2450-A which is really an early 2451 motor….

I have tried to find pictures of a ribbed SL dia, but cannot find one. Are you sure that the 2451SL dia is ribbed? Can there be more than one dia with the same partnumber? Do you have a picture?


Rgds
//RoB

[subwoof]

There are a few long and exhaustive threads on this that will clear up your questions. good luck finding them with this crude search - use google and make it site-specific.

2450SL and 2451 are the same motor but the diaphrams and the *mounting hole pattern* are different. your 2332 has holes for both patterns - ever notice that? JBL makes a 2 different series of larger 1.5" horns that use the wider pattern.

the 475 is a 2" Nd driver used in first gen K2 ( read: not for sale in US ) systems. it looks like the 2450 but the magnet is shielded.

The 2450SL is the driver used in the ARRAY series - I have many of them. They work anywhere flawlessly.

the 2452SL is the next gen of this with optimized magnet ( lighter ) and the special terminal extensions.

yes there are identical items with different part numbers - pro and consumer. Don't ask for a list - one does not exist. We experts charge a lot ( in strong IPA's ) just to impart our wisdom. And we do fail often trying to remember and JBL, in their infinite wisdom, has laid off anyone at northridge who remembers.

sigh

2450 is a 2" exit
2450SL is a 1.5" exit
JBL did this just to mess with our heads.
And to make it more funny, they use the 2450 number as replacement for the 2446 ferrite.
We aren't laughing.

2451SL isn't a good number - if it were it would be the SAME as the 2450SL-A but then again someone in JBL parts will read this and backdate a list somewhere just to spite us.

(again) sigh

[sebackman]

Thank you sub!

I know there is much info in various threads but not really in detail covering the different SL diaphragms offered by JBL. It also seem like there may have been other SL diaphragms that are no longer manufactured.

I knew about the dual mounting pattern on the horn. It was discussed here. I even posted some pictures there.

I still have one question.
Are the current 2451SL ribbed and the 2450 plain? Or are the currently by JBL offered D8R2450SL & D16R2451SL replacement diaphragms identical except for the impedance, i.e. smooth and coated.
I can’t find any pictures on our forum or on the internet showing a ribbed SL dia. In one of the earlier threads “speakerdave” reports having received two new “sealed box” D162451SL diaphragms and he reports them being “smooth and coated” (link). Maybe the boxes were mixed up but if they were sealed that sounds odd.

Most seem to agree that the currently offered JBL diaphragm D8R2451SL is smooth and coated. Now, is the currently offered D16R2451 replacement diaphragm identical to the D8R2450but except being 16ohms? If anyone does have a picture of an original SL coated (Aquaplas) JBL diaphragm with ribbs, please post it here.

D8R2450SL $264.00 2450SL (74114X)
D16R2451SL $234.00 2451SLJ

Regards
//RoB

[subwoof]

if the part number doesn't say "SL" on it, it's not coated. period.

2450 / 2451 / 2452 / 2446 / 2447 all use the 2450 ( ribbed ) dia. The available impedance's will vary with phases of the moon, length of a woodpeckers beak and air pressure in your spare tire.

The 16ohm coated models were only available then for the "con$umer" models - I see on the nov 2011 list that they are now available.

http://www.jblproservice.com/pdf/Tra...rts%20List.pdf

so the 2451SLJ *is* a coated, ribbed, 16 ohm dia.

It's when using the coated versions that the (old) numbering makes you crazy. Back when the DMS-1 , HLA and array monitors got their first dia change the 2451 wasn't a OTC item so the -a was used to show that the 2450SL dia is now ribbed. For no ones pleasure.

*skol*

[edgewound]

if the part number doesn't say "SL" on it, it's not coated. period.

2450 / 2451 / 2452 / 2446 / 2447 all use the 2450 ( ribbed ) dia. The available impedance's will vary with phases of the moon, length of a woodpeckers beak and air pressure in your spare tire.

The 16ohm coated models were only available then for the "con$umer" models - I see on the nov 2011 list that they are now available.

http://www.jblproservice.com/pdf/Tra...Parts List.pdf

so the 2451SLJ *is* a coated, ribbed, 16 ohm dia.

It's when using the coated versions that the (old) numbering makes you crazy. Back when the DMS-1 , HLA and array monitors got their first dia change the 2451 wasn't a OTC item so the -a was used to show that the 2450SL dia is now ribbed. For no ones pleasure.

*skol*

To the best of my knowledge...and it might be lacking...

All of the coated "SL" diaphragms are smooth....basically a 2445 with Aquaplas.

The 2450, 2451, both use the ribbed non-coated 2450 diaphragm.

The 2452 uses a ribbed non-coated diaphragm with screws removed for the pass through terminals and includes an orange O-ring seal.

All of these diaphragms are interchangeable. Choose your weapon based on impedance and coating if desired. SL diaphragms are smooth and coated...and are the best sounding for hi-fi application and about 1dB lower output from the added mass. I haven't seen a ribbed, coated diaphragm...yet.

[Mannermusic]

To the best of my knowledge...and it might be lacking...

All of the coated "SL" diaphragms are smooth....basically a 2445 with Aquaplas.

The 2450, 2451, both use the ribbed non-coated 2450 diaphragm.

The 2452 uses a ribbed non-coated diaphragm with screws removed for the pass through terminals and includes an orange O-ring seal.

All of these diaphragms are interchangeable. Choose your weapon based on impedance and coating if desired. SL diaphragms are smooth and coated...and are the best sounding for hi-fi application and about 1dB lower output from the added mass. I haven't seen a ribbed, coated diaphragm...yet.

And, as best I have been able to surmise, there are no coated aluminum, 16 ohm diaphragms (2440 or 41) as would be used in the old alnico drivers (2445 is titanium). Right?

[HCSGuy]

And, as best I have been able to surmise, there are no coated aluminum, 16 ohm diaphragms (2440 or 41) as would be used in the old alnico drivers (2445 is titanium). Right?

The idea of coating the titanium diaphragm with aquaplas came with the development of the 475ND in 1989, well after the change from aluminum diaphragms, which happened around 1984, with the 2441 out of program by 1986. Therefore, there are no factory coated aluminum diaphragms.

I have D8R2450SL, D8R2451SL, D8R2452SL, which are all smooth, coated domes. I also have one smooth coated 16ohm, though I'm not sure which series it is from - I'll check next time I'm digging around the shelves.

[sebackman]

Brilliant.

Thank you.

First of all, I'm only referring to SL diaphragms even if I may have missed the “SL” acronym in the text above in a few places this is the only topic.

The posts above indicate that the only difference between the various current SL diaphragms is the impedance and they are all smooth, titanium, similarly coated and fully interchangeable. Sonic differences, if any, should be minimal.

Now I only need three 8ohms SL diaphragms. -Anyone having some on the shelf for sale?

Best Regards
//RoB

[Mannermusic]

The idea of coating the titanium diaphragm with aquaplas came with the development of the 475ND in 1989, well after the change from aluminum diaphragms, which happened around 1984, with the 2441 out of program by 1986. Therefore, there are no factory coated aluminum diaphragms.

I have D8R2450SL, D8R2451SL, D8R2452SL, which are all smooth, coated domes. I also have one smooth coated 16ohm, though I'm not sure which series it is from - I'll check next time I'm digging around the shelves.

OK, got it, many thanks. Print and file! You had a good English Comp prof - a pleasure.