Pinholes in Ti Domes

[2pair]

...I was just sitting here examining my tweeters with a flashlight (I have nothing better to do..) :o: and I noticed a tiny pinhole in one. I of course had to look at the other and saw exactly the same hole.

They are 035tia's in 4408. Is this normal? Some part of the manufacturing process? They don't look damaged at all...just have a tiny hole. It wouldn't be to balance pressure on both sides, or something, would it? :blink:

Thanks
Dave

[johnaec]

Where exactly are the pinholes located? I've got a bunch of 035Ti/A's I can look at later.

John

[2pair]

...Right on the dome, about a quarter inch from the center,about the same to the edge of the dome. 1 o'clock on one, 11 o'clock on the other...

[edgewound]

...Right on the dome, about a quarter inch from the center,about the same to the edge of the dome. 1 o'clock on one, 11 o'clock on the other...

Believe it or not, that's normal. I'ts said to release pressure under the dome.

[2pair]

That was the only thing I could think of, that or maybe a remnant of the molding/stamping process. I needed to know or I wouldn't have got any sleep...:nutz:
Thanks...:snore:

[Titanium Dome]

if it weren't there as the thing heated up under extreme use.

Go ahead, imagine.

Now, what would the result be? ;)

[2pair]

Well....Don't leave me hanging....!
What would happen?
:dont-know

[Zilch]

A compression driver? :p

[soundmotor]

Believe it or not, that's normal. I'ts said to release pressure under the dome.

I'd bet the tweeters you are referring to have ferrofluid in the voice-coil gap too. The pressure release is typically not needed on non-ferrofluid cooled ones IME.

[edgewound]

I'd bet the tweeters you are referring to have ferrofluid in the voice-coil gap too. The pressure release is typically not needed on non-ferrofluid cooled ones IME.

Neither the 035tTi nor the 035TiA has ferrofluid. I was informed by the factory several years ago that the pinhole was put in the dome to release any built up pressure or rarefaction under the dome that could lead to any deformation of the titanium dome and accomapanying distortions. Later production models and repair kits were fitted with a higher stack of foam buttons that exerts a small amount of support and damping to the backside of the dome. I hope this lays to rest any thoughts of the possiblilty of the tweeter bursting into flames or total melt down due to extreme amounts of input power.

[soundmotor]

Neither the 035tTi nor the 035TiA has ferrofluid. I was informed by the factory several years ago that the pinhole was put in the dome to release any built up pressure or rarefaction under the dome that could lead to any deformation of the titanium dome and accomapanying distortions. Later production models and repair kits were fitted with a higher stack of foam buttons that exerts a small amount of support and damping to the backside of the dome.

I've worked for 3 driver manufacturers over the years but on the consumer side (& still do). Your description vs. the following illustrates the broad differences in design technique that arrive at the same point.

The pinhole at one company was to release pressure as the voice-coil was seated down into the magnetic gap as the ferrofluid (FF) made an effective gasket. That is what made me think FF. You got a pressure build-up behind the dome that affected performance. On non-FF tweeters made by them, there was enough air space down in the gap, that the pressure build-up was neglible. After the tweeter was fully assembled, the pinhole was sealed with essentially glue. In this case, it was a doped cloth or plastic dome. A domed, felt plug was also used behind the dome but it did not touch as the JBL one evidently does. (The JBL one might have a secondary function to damp dome resonance at some HF.)

At another manufacturer, FF was used but no hole in their titanium dome. On the larger drivers, a small piece of fiberglass bat was placed behind it. On the smaller ones, nothing was used. In this case, the slightly compressed air behind the dome was used as the back support & all else be damned! At their limit, one could say these drivers were a tad.....hot! Maybe two tads.

On the metal dome drivers we make at my current employment, the surrounds on the drivers are porous thus providing the pressure release. These too are FF filled and have an open-cell foam dome plug. The plugs used behind the domes in the 1st & 3rd examples attenuate/control acoustic reflections off the back of the dome into the cavity.

All neat stuff!

[2pair]

..Thanks for the info guys. I dont understand a lot of it, but I appreiciate knowing the holes should be there.:)

Dave

[2pair]

I'm finally comfortable with holes in my domes and the reasons for them, so when I got ANOTHER pair of speakers today (L20t) I looked at the tweeters. And guess what? NO holes! :banghead: Now I'm concerned because of this. Should I be? Is it because these don't have as high a power handling? :dont-know

[edgewound]

I'm finally comfortable with holes in my domes and the reasons for them, so when I got ANOTHER pair of speakers today (L20t) I looked at the tweeters. And guess what? NO holes! :banghead: Now I'm concerned because of this. Should I be? Is it because these don't have as high a power handling? :dont-know

Don't worry about it....different theories and different remedies at different production times. Get some sleep...:)

[soundmotor]

I'm finally comfortable with holes in my domes and the reasons for them, so when I got ANOTHER pair of speakers today (L20t) I looked at the tweeters. And guess what? NO holes! http://audioheritage.org/vbulletin/images/smilies/banghead.gif Now I'm concerned because of this. Should I be? Is it because these don't have as high a power handling? http://audioheritage.org/vbulletin/images/smilies/dont-know.gif

http://www.discountknivesonline.com/images/30483.jpg

[2pair]

...that might work! :hmm:

:rotfl: