Why did JBL choose aquaplased Ti-diaphragms over the good old AL-diaphragms...?

Hey folks,

the old Alnico drivers with ALuminum diaphragm such as the 2440 and 2441 are still sought after because of their great sound.
JBL changed these to Titanium diaphragms in their ferrite successors like the 2445 because of their greater resistance....
The 2450sl is the newest of the mentioned drivers and was used in hifi and studio-monitors, but not in pro audio if I remember correctly!?
The 2450sl uses an aquaplased Titanium diaphragm and it´s primarily purpose is to sound good, not resistance!

Why does JBL use aquaplased Ti dia´s instead of AL dia´s in a sound quality speaker :confused:

I know the aquaplas coating reduces resonances and the "ringing" of the Ti dia´s.... But why wouldn´t JBL use a less "ringing" material such as Aluminum right away, instead of using a material of less audio quality and correcting it´s "faults" afterwards by coating it with damping material?
If these drivers where used in pro audio at concert levels all day, I would understand choosing the more resistant Titanium.
But isn´t the Aluminium resistant enough for quality sound applications at studio environments?

Or did the guys at JBL believe the aquaplas coated Ti diaphragms do even sound better than the Al diaphragms?

JBL found Ti to have vastly superior in-field endurance, but discovered that they were a bit harsh so they used the coating to mitigate this in more critical applications. In recent years for home use they have gone back to AL in the more "affordable" high end offerings and Mg or Be in the higher end models.


Widget

Isn't the 435AL-1 aquaplased aluminum?

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Originally Posted by JeffW

Isn't the 435AL-1 aquaplased aluminum?

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Yep.


Widget

Thanks a lot for your short summary! :)

Besides the better endurance of Ti, how do aquaplased Ti and Al compare soundwise?
So far I have tried used D16R2441 Al, used D16R2445 Ti and new Radian 1245 AL.
But I have not listened to D16R2450sl aquapl. Ti yet....
So far I prefered the JBL Al, the Ti was to harsh and the Radian a little too soft.

Does the aquaplas coating of the Ti diaphragm veil or curtain the audio-microdetails of a recording or does it sound as transparent as an Al diaphragm ?

Are there any drawbacks compared to the Al dia´s ?

I believe there are many facets to this question which many have been touched on already but here is a little food for thought:

A manufacturer can make what they need as product and demands change. One examble, a 2311/2308 will go straight out to 16kHz driven by a 2441 with nearly no signal shaping. Put that driver on a 2360 and not only is it done before 12kHz but will sound close to terrible if you try to EQ it anywhere near what a 2450 will do with no EQ. Put a 2450 on a 2311 and get ready to run!

JBL doesn't use large format drivers in domestic speaker systems often. For high end domestic use, consider this: What did JBL use in the K9500? Aquaplassed smooth Ti in a 2450. It wasn't their only option. The D8R475Nd and D16R475Nd diaphragms are a performance bargain. They extend better than the D8R2450Sl or the D16R2451Sl's but you can't play them at PA levels like you can the Sl's. In my opinion, only the 476Mg and 476Be outperform the 475Nd and a big part of that is an improved motor and phase plug.

2440 and 2441 diaphragms are still available from JBL.

There really is much to consider.

Barry.

Quote:

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Originally Posted by Dr.db

...Does the aquaplas coating of the Ti diaphragm veil or curtain the audio-microdetails of a recording or does it sound as transparent as an Al diaphragm ?

Are there any drawbacks compared to the Al dia´s ?

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The micro detail question is tuff. I like D16R24441's a lot for that reason but usually use a tweeter with them. D8 or 16475Nd generally with no tweeter.

The real issue with aluminum verses Ti, there is a fairly large range of bending where there is virtually zero fatique with Ti ie if you aren't killing it, you can repeat it forever. With aluminum, the clock ticks with every cycle, slower with small deflections and much faster with large deflection but ticking with every cycle.

Barry.

Hi Barry,


thanks a lot for all that input! :)

You have exceeded your stored private messages quota and cannot accept further messages until you clear some space. So I´m answering you here...

I had some worn out 2441 drivers with original diaphragms and sold them due to bad rusty cosmetic conditions. The sound was great though!
Now I got a brand new pair of 2446 drivers. I listened to the non coated Ti diaphragms and didn´t like em. Swapped in some new Radians and they are ok, but not the real deal.
Now I´m thinking about purchasing either the D16R2451sl or the D16R2441 diaphragm in new condition. Unfortunatelly I havn´t the money to purchase both and compare, so I´m hopping to benefit from your and other forum members experience.

The midrange will be used with crossovers at 1,2khz and 10khz with a 2405 on top.
The horns I´m using these with are the 2397 e.g. westlake copies, you can watch my DIY-build here:
http://www.audioheritage.org/vbulletin/showthread.php?38804-Tribute-to-Lansing-Heritage-Forum-and-new-DIY-build!!&p=397414#post397414

Would you say microdetail is better with 2441?
Do the aquaplased Ti only have their advantage in the extended range above 10khz?
Which one does sound more dynamic in your ears ?

Comparing the D8R475nd and D16R2451sl....
I thought these were identical besides the impedance!?
Both are aquaplased coated Ti, one is commercial and one is pro equipment...
I thought these would sound the same.
And I need 16ohm and cannot find any D16R475nd, just the D8R475nd seems to be available...


Thanks a lot,
Olaf

Hi,

Indeed they are the same. I new have D8R2450SL, D16R2450SL and D8R475Nd. They are the same and they measure the same.

Now the 2450SL come in both 8 and 16 ohms. I have both, one set has red dots and the other green dots. The D8R475Nd seem to be only 16 ohms. I ordered D8R475Nd and got just that, at least that is what the box said. However they were all 16 ohms....

So SL's exist in 16 and 8 ohms. 475Nd's appears to be only 16 ohms.

Sound wise I like the SL' better than any Ti or Al diaphragm. I even prefer the SL's in my system over the Be's. I don't have any Mg's but pretty much all of the other diaphragms and motors. :-)

kind regards
//RoB