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toddalin
12-09-2008, 02:39 PM
Has anyone put an 077 diaphram into an 075 that can tell of their results? Disregarding dispersion, what were the resultant frequency response and smoothness like?

Thanks

scott fitlin
12-09-2008, 04:28 PM
Has anyone put an 077 diaphram into an 075 that can tell of their results? Disregarding dispersion, what were the resultant frequency response and smoothness like?

ThanksSomeone I know did this, he says it sounds better. Goes up higher, and sounds more hi fi, less raspy, to quote this person. And as the 077 diaphragm is lighter it should, I guess.

I don't think it will affect the bullets dispersion, the phase plug, and horn type have more to do with that.

Of course, never having done this myself, I have no idea what it will sound like or not.

robertbartsch
12-10-2008, 04:08 AM
There are several threads here that discuss this topic.

grumpy
12-10-2008, 07:43 AM
http://www.audioheritage.org/vbulletin/showthread.php?t=7265&highlight=2405+diaphragm+2402

http://www.audioheritage.org/vbulletin/showthread.php?t=19986&highlight=2405+diaphragm+2402

with a few links embedded.

Not clear to me that what you are proposing to put together
would work in a pre-defined way... sweeping statements aside.

toddalin
12-10-2008, 11:16 AM
http://www.audioheritage.org/vbulletin/showthread.php?t=7265&highlight=2405+diaphragm+2402

http://www.audioheritage.org/vbulletin/showthread.php?t=19986&highlight=2405+diaphragm+2402

with a few links embedded.

Not clear to me that what you are proposing to put together
would work in a pre-defined way... sweeping statements aside.

Trying to get rid of the dip between 8-10K. When I swept a 2404, the dip wasn't there. The dip has the effect of dulling the highs and in my testing this range is what gives the 2404 the clarity and sizzle over the 2402.

Dispersion characterics are not really an issue as I sit in the "sweet spot" 100% of the time.

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=8612&stc=1&d=1119510864[/img]

Thanks for the link. Couldn't this interference with the diaphram have been solved sinply using a thin washer between screw-pad to push the nose-cone out a little more?

http://www.audioheritage.org/vbulletin/attachment.php?attachmentid=32326&stc=1&d=1209445100

grumpy
12-10-2008, 12:55 PM
Unless I completely don't understand how these are assembled (a distinct
possibility), the inner portion of the diaphragm is clamped in place by a portion
of the "ring" at the base of the 'bullet'/wedge/cone, and is simply pulled in
(the clamping force) by tightening the screw into the center shaft of the phase plug.

That there may need to be some clearance added with some mix of phase plugs
and diaphragms is more than I know, but would seem to be in the form of an added
thickness at the inner portion of the "clamping ring" surface... or milled away from the
outer portion of same ring.

:dont-know Someone box my ears if I'm wrong. :)

toddalin
12-10-2008, 01:13 PM
Unless I completely don't understand how these are assembled (a distinct
possibility), the inner portion of the diaphragm is clamped in place by a portion
of the "ring" at the base of the 'bullet'/wedge/cone, and is simply pulled in
(the clamping force) by tightening the screw into the center shaft of the phase plug.

That there may need to be some clearance added with some mix of phase plugs
and diaphragms is more than I know, but would seem to be in the form of an added
thickness at the inner portion of the "clamping ring" surface... or milled away from the
outer portion of same ring.

:dont-know Someone box my ears if I'm wrong. :)

It looks to me that the machined portion fits within the central hole of the diaphram and the machined "lip" would be what holds the the central ring of the diaphram inplace.

Upon further examination, putting a washer or shim at the screw pad would also lift the lip from the cental ring of the diaphram. (This is why machining the nose cone for tolerance would be the preferred method so that everything is held in-place as normal.) If the washer were added under the screw pad, a ring of equal thickness would need to be to be placed on the machined shaft at the machined lip to take up the slack.

But, that's just the way it looks to me and I could also be wrong. Needless to say, it is not a simple drop in, at least with a factory-correct replacement diaphram.

grumpy
12-10-2008, 02:00 PM
...putting a washer or shim at the screw pad would also lift the lip from the cental ring of the diaphram.That was my concern. I don't -think- it would be necessary to shim the screw pad,
other than to make it more difficult to over tighten the screw.

...I should probably find a dead unit to disassemble.

Jakob
12-11-2008, 02:39 AM
Help me out here. I thought 2402 and 2404 and 2405 dias all were the same and that it was the horn assembly that decide what response You get?

grumpy
12-11-2008, 07:56 AM
If I've got this right...

There are at least three ring radiator diaphragms in this general form factor:

D16R2405 - for 2404H, 2404H-1, 2405, 2405H, 077

D8R075 - for 075R, 2402, 2402H, 075-022, 075-105,
075-105B, 075-105C, 075-105CH, 075-105D

D8R076 - for 076, 2403, 2403H

toddalin
12-13-2008, 02:36 PM
I had a thought. If it is the matter of adding a proper diameter shim, the central ring from the old diaphram could be used.

When I removed a diaphram from a blown 2404 (which had a 2402 diaphram, as do the other two 2404s), I found that the "cone" is an aluminum foil sandwiched between two brass rings along the inner and outter diameter.

A "thick" shim would be to leave both pieces of brass sandwiched while a "thin" shim would use just one, assuming it could be pryed apart without damage.

But I think it may go beyond that and the surface of the phase plug as well as that of the top plate are mated to the proper diaphram contour.

Still, it would be interesting to try to shim a 2405 diaphram (if I had one) into a 2402 for sonic testing.