075/2402, 076/2403, 2404, 077/2405

[Techbot]

All three diaphragm kits D8R075, D8R076, and D16R2405 use the same voice coil part number.


(All three diaphragms have the same DCR specification regardless of any D8R versus D16R assembly number prefix. Actual transducer impedance will vary depending on diaphragm loading.)


Both D16R2405 and D8R075 use the same diaphragm part number. D8R076 uses a different diaphragm (dimensions).


All three kits use the same raw diaphragm material (.002 inch thick Aluminum).


There are also some differences on the diaphragm spacer rings used in each kit,


Information courtesy of JBL


Note that the D8R076 diaphragm assembly has also been labelled D16R076 in past years.

[Techbot]

Since the late 50’s there have been many variations.

Basically there is only one diaphragm (2 mil aluminum), one coil impedance, and a variety of clamp ring diameters.

For a while, we did have a 1.6 mil diaphragm but I think those are long gone.

There is a clamping ring on the interior and exterior of the diaphragm. This ring comes in silver and blue. The blue ones have different ID’s and OD’s than the silver ones.

The differences in the diaphragm assemblies come from whether the assembly has two silver, or two blue or a mix of silver and blue rings. This changes the clamping diameters and thus the stiffness of the diaphragm.

Over the years, things have changed with the aluminum and the way the diaphragms are creased at their outer edge. This led to the different rings.

To my knowledge, all of the motor assemblies are interchangeable from a mechanical standpoint. The ferrites probably have a little more flux level than the alnico’s but that is all. The main difference in them is the horn or bullet or whatever is mounted on the front side. Any diaphragm can go in any body. Results will vary.


Information courtesy of JBL

[Techbot]

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