075 Diaphragm replacement & Gap

[Jimbo]

My father-in law's 075 tweeters need the diaphragms replaced. I contacted JBL and was told that he could use the 2405 diaphragm if the phase plug was milled down to create the proper air gap. My question is what is the proper air gap? And where can I have these phase plugs sent to be milled to the proper size? Or can they be replaced by another properly sized phase plug? JBL wont help with this repair nor would they recommend anyone to help us. Any idea's forum members?

[clubman]

I know a guy in the kansas city area that might be able to help. If you run out of options I could give you his number. He handles all of my recones and speaker repairs.

[rs237]

My father-in law's 075 tweeters need the diaphragms replaced. I contacted JBL and was told that he could use the 2405 diaphragm if the phase plug was milled down to create the proper air gap. My question is what is the proper air gap? And where can I have these phase plugs sent to be milled to the proper size? Or can they be replaced by another properly sized phase plug? JBL wont help with this repair nor would they recommend anyone to help us. Any idea's forum members?

hello Jimbo,

I think this is a false information. Read this tread (Particularly post 122)

http://www.audioheritage.org/vbullet...ead.php?t=6368

All ring radiator (075,076,077, 2402,2403,2405) dias are interchangeable without mechanical modification.

regards
juergen

[Zilch]

I think this is a false information.

Indeterminate. The proper diaphgram for 075 is D8R075.

Why are we putting D16R2405 in 075? We KNOW they are different diaphragms.

Trying to get extended UHF response out of 075? Willing to give up power handling and/or frequency response at the low end?

Look at 2403, 2404 and 2404H-1; there are two different conical phase plugs.

The info may be accurate, based upon different diaphragm excursions....

[rs237]

Thanks Zilch,
you are right. My englich is very bad, that's why I yes to the post by Rudy Kleimann noted.

Regards
Juergen

[Jimbo]

JBL does not make the proper diaphragms for the 075, You have to use the 2405 and make modifications to achieve the proper air gap. At least this is what I was told my a tech at JBL.

[subwoof]

It sounds like you took 30 minutes of questions / answers / information and condensed it into a single sentence and misunderstood him.

Many of us here know these "techs" personally, what is his name?? And how about posting a picture of this special model that needs this kind of work done to it?

sub

[rlh100]

[quote=Jimbo;200330]My father-in law's 075 tweeters need the diaphragms replaced. I contacted JBL and was told that he could use the 2405 diaphragm if the phase plug was milled down to create the proper air gap.

I am having the same issues and I believe the thread is wrong about the 075/2402 and 2404/2405 diaphragms being interchangeable. I am building some floor monitor speakers modeled after the Cabaret 4602A but in a smaller cabinet. I have a bunch of 2402's that need new diaphragms and am looking into aftermarket diaphragms They are 1/4 the price and I need 6, besides these are floor monitors and it is rock'n'roll. I exchanged email with Eric Sunda at Orange County Speaker about their aftermarket diaphragms and was told they were not interchangeable because of some dimension mis-matches. Being brave and having experience as a machinist, I went ahead and ordered one to check it out. And you know what, Eric was right. The problem is with the back profile of the bullet itself. It has a slight angle to match the profile of the diaphragm and the lip of that angle touches the diaphragm.

The first two photos are the back profile of the bullet.

The second two photos are a real 2402 diaphragm. I believe it is out of a 2402, not a 2402H. Note how there are 3 rings in the diaphragm profile.

The last photo is the after-market 2405 diaphragm. Note how it does not have the inner ring in the diaphragm profile. If you look closely you will see a whitish ring just inside the bottom of the profile where the voice coil attaches. This is where the edge of the bullet rubbed against the diaphragm itself.

As to whether or not this can be worked around, I am still trying. First off, milling the bullet would not make sense because you would loose the slight angle to match the profile. You could turn it on a lathe, but it would be tricky to get the same angle. What I am going to try is a shim between the front of the inner ring of the diaphragm and bullet to push it away from the diaphragm. This is the simplest solution and would not modify the driver. This would allow me to go back and use the 075 diaphragm if I want to.

Stay tuned for further results. It will be interesting testing this because the 2402 is crossed over at 3 K or so and my hearing dumps at about 12 K on a good day (:-), so I will be listening in the upper 2 - 2 1/2 octaves of my hearing.

I hope this helps

RLH

[4343]

I've seen this before with a 2405 from epay. It was barely putting out any sound until I loosened the phase plug mounting screw. I cut a shim out of masking tape to see if it would help, and it did. Full volume took several layers. Non-scientific, YMMV...

I figured it must have had a diaphragm swapped at some point, but have not investigated further. (It did appear to be a genuine JBL part though.)