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Author Topic: shattered titanium diaphragm on ETX but coil fine?  (Read 2266 times)

Seth Albaum

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shattered titanium diaphragm on ETX but coil fine?
« on: June 22, 2018, 10:58:40 AM »

Well, this weird.

High freq driver in an ETX 15SP sounded dead. Brought it to my authorized repair place - people I know, actually.

Electronics replaced, but HF sounded muted/soft. I brought my other ETX in for A/B. Confirmed.

Turns out the titanium diaphragm shattered, and perhaps was partially able to still reproduce sound. Everything else measured fine. Coil measures fine.

HOW? WHY? WHAT?

I don't know, so I'm posting here to seek input on how it may have happened and how to prevent it from happening again. I'd like my ETX's to last through a rather grueling summer season before needing even more repairs, at least. can't afford to shop around for something else right now.

Thanks
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Tim McCulloch

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #1 on: June 22, 2018, 11:23:01 AM »

HF diaphragms shatter due to repeatedly striking the phase plug of the driver.  Either the crossover failed in a manner that allowed too-low frequency signals to the HF or the phase plug has shifted due to adhesive failure or the speaker being dropped.

Ivan B may know of other failure modes but those are the most common.
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Seth Albaum

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #2 on: June 22, 2018, 11:29:43 AM »

HF diaphragms shatter due to repeatedly striking the phase plug of the driver.  Either the crossover failed in a manner that allowed too-low frequency signals to the HF or the phase plug has shifted due to adhesive failure or the speaker being dropped.

Ivan B may know of other failure modes but those are the most common.

Hm.. well, they're used in all manner of outdoor gigs, so perhaps adhesive? Shouldn't something really durable be used? I will mention the phase plug when I pick them up today. Last thing I need is for it to happen again..

Thanks
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Tim McCulloch

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #3 on: June 22, 2018, 11:33:20 AM »

Hm.. well, they're used in all manner of outdoor gigs, so perhaps adhesive? Shouldn't something really durable be used? I will mention the phase plug when I pick them up today. Last thing I need is for it to happen again..

Thanks

The tech can compare it to a known-good unit, measuring the height of the phase plug above the driver top plate and checking for looseness.  If the phase plug is loose or if it's firmly attached but sitting proud, this should be a warranty claim... but my bet is on crossover failure.
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Mike Caldwell

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #4 on: June 22, 2018, 11:35:49 AM »

If the coil is still intact a shattered diaphragm will still make
sound/noise of some sort depending on how bad it’s cracked or
shattered.

If the voice coil is not burnt or looking overheated I would say it was a combination of metal fatigue and getting hit with a few sudden burst of high sound level.

Join the club, anyone who says they have never had a blown or shattered a diaphragm is lying!

A tone sweep test makes it pretty obvious when you have even
a cracked diaphragm let alone shattered, kind of surprised they did
not test the speaker with a tone sweep.

If they are going to replace just the diaphragm make sure they clean the driver gap really well and then when they think they have gotten all the bits of shattered diaphragm out it they need to clean it again.

I'm guessing you posted the wrong model number of speaker, the model you posted is a subwoofer.
« Last Edit: June 22, 2018, 11:55:23 AM by Mike Caldwell »
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Seth Albaum

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #5 on: June 22, 2018, 11:39:43 AM »

If the coil is still intact a shattered diaphragm will still make
sound/noise of some sort depending on how bad it’s cracked or
shattered.

If the voice coil is not burnt or looking overheated I would say it was
a combination of metal fatigue and getting hit with a few sudden burst
of high sound level.

Join the club anyone who says they have never had a blown or shattered a diaphragm
is lying!

A tone sweep test makes it pretty obvious when you have even
a cracked diaphragm let alone shattered, kind of surprised they did
not test the speaker with a tone sweep.

If they are going to replace just the diaphragm make sure they clean the
driver gap really well and then when they think they have gotten all the
bits of shattered diaphragm out it they need to clean it again.

I'm guessing you posted the wrong model number of speaker, the model you posted is a subwoofer.

You're right - I'm talking about the two-ways..

I'll bring these things up. Don't know why they didnt' tone sweep. I have an HP oscillator in my home office, even..
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Mike Caldwell

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #6 on: June 22, 2018, 11:54:38 AM »

The tech can compare it to a known-good unit, measuring the height of the phase plug above the driver top plate and checking for looseness.  If the phase plug is loose or if it's firmly attached but sitting proud, this should be a warranty claim... but my bet is on crossover failure.



I'm going to with pushing the system to the limits with a few high level signal spikes thrown in, just more than the internal limiting could handle.
That is not the most high power driver used in those cabinets.

It would be an easy test to check the amp modules either with something like SMARRT or a low tech test of hooking the high frequency output to the woofer and with pink noise to see if you can hear more low frequency from one amp or the other.

What kind of shows do you use the system for.

Seth Albaum

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #7 on: June 22, 2018, 12:41:50 PM »



I'm going to with pushing the system to the limits with a few high level signal spikes thrown in, just more than the internal limiting could handle.
That is not the most high power driver used in those cabinets.

It would be an easy test to check the amp modules either with something like SMARRT or a low tech test of hooking the high frequency output to the woofer and with pink noise to see if you can hear more low frequency from one amp or the other.

What kind of shows do you use the system for.

System gets used for everything from talks in museums to outdoor "pop-up" drive ins near the ocean, rock bands, DJ's.. I'm always watching levels, but basically, they're used for everything.
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Ivan Beaver

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #8 on: June 22, 2018, 12:57:19 PM »

HF diaphragms shatter due to repeatedly striking the phase plug of the driver.  Either the crossover failed in a manner that allowed too-low frequency signals to the HF or the phase plug has shifted due to adhesive failure or the speaker being dropped.

Ivan B may know of other failure modes but those are the most common.
That is pretty much it.  Sometimes the glue will fail that holds the diaphragm to the surround, VC former, or it will tear.

I have seen some in which a high level oscillation at a particular freq will cause them to "warp out of control" and shatter.

Sometimes it is just a piece of defective material.  A small problem in one place will "expand" and tear it up.
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Dave Pluke

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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #9 on: June 22, 2018, 07:29:22 PM »

I have seen some in which a high level oscillation at a particular freq will cause them to "warp out of control" and shatter.

Yeah, in addition to the over-excursion theory, I was wondering if simply pumping too much ultra-high EQ could also fracture the diaphragm.

Years ago, I fractured the aluminum dust covers on some Altec 417-8H speakers in my Twin Reverb.  Can't blame the phase plug on that one...

Dave
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Re: shattered titanium diaphragm on ETX but coil fine?
« Reply #9 on: June 22, 2018, 07:29:22 PM »


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