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Tweeter Dome Damage Effect

Any physics text will tell you that, unless you are very close, the size of the sound source affects dispersion more than shape. So it is more likely that the dent affects the frequency response than the dispersion. If they sound wrong, the exact cause is of little concern, but if you don't hear any problem, it may be because there isn't any. Seeing - that's different.
 
Nat said:
Any physics text will tell you that, unless you are very close, the size of the sound source affects dispersion more than shape. So it is more likely that the dent affects the frequency response than the dispersion. If they sound wrong, the exact cause is of little concern, but if you don't hear any problem, it may be because there isn't any. Seeing - that's different.
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I'm dying for someone to REW chart "before and after" dome straightening, on axis and off axis. That picture will be worth a thousand words :).

My experience with my Allison roughly mirrors what you are saying, but I couldn't have been less scientific in evaluating before and after (I guess because I didn't think about doing a formal comparison, and also because I didn't really believe I would be able to fix the dome until it was done).
 
I've made measurements and the pushed domes cause problems when the dome itself makes contact with the magnet. Small dents don't have measurable effects (at least with my standard electret mic). But smashed domes do distort the sound.

I've fixed some titanium domes from the outside (sealed units where you can't remove the dome easily), using contact cement and a tooth pick. The glue doesn't adhere too much to the titanium, so you apply a bit on the dome and after some seconds you can stick the toothpick to it and pull. Or apply some glue to the toothpick too. With some practice the results are very good. I can upload picts tomorrow
 
If not seeking perfection you will be ok but most audiophiles couldn't live with the thought of a crushed in dome....
 
I'd like to see a before and after polar dispersion graph of a tweeter with a partially dented dome. A graph something like this

fourthdrawing.jpg
 
botrytis said:
That is why I want my speakers to have a mesh, etc. over the domes so little fingers can't push them in.
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The one in my reply above has a screen over the dome. Unless that screen is quite strong, it won't help prevent damage from curious children. Or movers! I left out the part of the repair that involved straightening the screen.
 
BMWCCA said:
The one in my reply above has a screen over the dome. Unless that screen is quite strong, it won't help prevent damage from curious children. Or movers! I left out the part of the repair that involved straightening the screen.
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True dat. I got a pair of Minimus 7 for free 'cuz the seller said they made a terrible noise when played. Turns out the metal grill was pushed against the dome, on both speakers. The domes were undamaged - not even dented. I straightened the metal grills and they sound great.
 
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this is how a creased KEF t33 measures. No fixing this one.
 

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Hi I have the same tweeters that need this repair. How did you get the front screen off of the tweeter and get it back on again?
Thanks!



BMWCCA said:
I did a titanium JBL tweeter a friend gave me. Turned out pretty well but it was easy to disassemble to get behind the dome.
Here is before, during the repair, and all back together:

51644998843_8f1fd1a4d7_b.jpg


51645626520_d94b32a29e_b.jpg


51644771731_8176bc0825_b.jpg


To be honest, the titanium felt a bit brittle but I figured with the foam damper to support the dome, it was pretty functionally as-new.[/QUOTE
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Riccardo77 said:
Hi I have the same tweeters that need this repair. How did you get the front screen off of the tweeter and get it back on again?
Thanks!
Click to expand...

You'll need a pin, needle, or small pick to carefully remove the O-ring that goes around the screen's perimeter. Once you've removed the O-ring the screen should easily lift off. Sometimes the magnetic attraction is all that's holding the screen in place.

Just had to do one again last night. Bought a pair of JBL 240ti and one tweeter was bad. No DCR. Took it apart to see if there was a physical problem with a connection rather than a fried VC. No luck. Anyone have a spare 044ti they'd be willing to part with?
 
Thanks very much !
What did you use to push out the dent?


BMWCCA said:
You'll need a pin, needle, or small pick to carefully remove the O-ring that goes around the screen's perimeter. Once you've removed the O-ring the screen should easily lift off. Sometimes the magnetic attraction is all that's holding the screen in place.

Just had to do one again last night. Bought a pair of JBL 240ti and one tweeter was bad. No DCR. Took it apart to see if there was a physical problem with a connection rather than a fried VC. No luck. Anyone have a spare 044ti they'd be willing to part with?
Click to expand...
!
 
BMWCCA said:
Mostly my finger with a little burnishing with my fingernail from inside the dome. Light touch, the titanium is very thin and brittle, but still malleable, to a degree.
Click to expand...

Thanks very much! I assume everything went back together ok and working again. That is great!
 
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