alnico/ferrite drivers

[Don McRitchie]

The aquaplas coating is intended to damp resonances within the titanium diaphragm. I'm guessing that the ribs, while stengthening the diaphragm at high output, create phase anomalies of their own due to the ridges in the otherwise spherical surface. It was probably not felt to be an issue in pro applications, but became a concern in hi-fi use. FYI, JBL was using the aquaplas coating on their ribbed pro titanium diaphragms for a time, but I don't think they are now. I'm not sure why they stopped.

[Robh3606]

Not sure about those ribs being a concern or not. Figure the 044,035,046 all have them to stiffen the diaphram. So does the very large 093ti dome.

[4313B]

Oops, it appears there are a few pages missing from this:

http://lansingheritage.org/html/jbl/...rs/1984-ti.htm

[Don McRitchie]

Personally, I remain to be convinced that they make an audible difference. Nonetheless, JBL went out of their way to develop a specialized diaphragm for the 475ND that removed the ribs from its pro counterpart.

[scott fitlin]

Originally posted by Don McRitchie
Personally, I remain to be convinced that they make an audible difference. Nonetheless, JBL went out of their way to develop a specialized diaphragm for the 475ND that removed the ribs from its pro counterpart.

But that JBL did take the time, and invest the money, into making a differing diaphragm says to me JBL felt it made an audible difference, and did what they may have felt was more suitable for each diaphragms intended application.

I am of the opinion that minute design changes in both driver assemblies, and diaphragms and materials and shapes and ribs, etc, do make audible differences.

[Maron Horonzakz]

Yes and now try to get a 475nd diaphram.

[scott fitlin]

Are the 475nd diaphragms hard to get?

[4313B]

No, they are in stock.

[Maron Horonzakz]

HMMMMM....So now here is the punch line question... What is the difference between the diaphrams of the 475nd coated units and the 2450SL coated aquaplaz diaphrams ???? IS one smooth faced? Is the other embossed ribbed? Or are both smooth faced and coated. We do need a JBL engineer here to give us the details. A chart would help. AS you have figured out I love to swap diaphrams & tweek for any sonic improvements . (if any) Too bad TAD diaphrams won,t fit large JBL drivers. But with a little machineing they might fit. (probably waste of time)

[Robh3606]

Heres a 475nd

[Robh3606]

Here's a ribbed

[4313B]

Originally posted by Maron Horonzakz
We do need a JBL engineer here to give us the details. A chart would help.

The chart is in the works with input from at least four people from JBL but it will be awhile. Everyone is very busy.

[spkrman57]

Reading older threads and trying to learn(old dog-new tricks). Thought this thread needed to be brought back to the present.
Ron

[tomt]

any chart yet?

or is this a dud deal?

[Maron Horonzakz]

I,m still holding my breath, but I,m turning blue.