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Old 15th February 2013, 05:43 PM   #11
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Quote:
Originally Posted by djk View Post
Pyro is more likely to blow HF drivers.
Back in the day, Reo Speedwagon toured with DB sound.
One of their pyro guys had the idea of mixing two different brands of powder together at a large stadium show, as it turned out the sum was greater than the parts.

The concussion mortar had an iron base about 6" x 6", the downward thrust from the explosion was enough to drive it through 3/4" of fiberglass coated Baltic Birch on the cabinet it sat on.

Although the FOH and monitor engineer had muted all the open microphones, around sixteen 15" drivers loaded in FLH horns in close proximity to the "event" suffered ripped cones and/or smashed voice coil formers, but no HF drivers were blown, and they were as close to ground zero as the LF drivers that blew.

At any rate, with "normal" pyrotechnics, DB sound had not had any problems with driver loss (as long as they muted the PA before the big bombs), the one described was a doozy, and not repeated.
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Old 15th February 2013, 08:04 PM   #12
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I had problems with Pyro tearing the Nomex voice-coil formers on Altec 288s right where they attach to the dome. The LF drivers never failed, but I never saw a situation as what you described (insanity).

I'll have to ask Bruce Knight from DB about that era, he lives locally.
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Old 15th February 2013, 08:14 PM   #13
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Alright guys my system is set up outdoors hundreds of feet from the pyro and facing away from the launch site, so I dont think thats it.
I made a little power meter and hooked up the subs.
It seems they could could have been inadvertently over powerd.
I was seeing over 500 watts depending on how much bass was in the songs.
I must have done something wroung calculating the attenuation needed to keep the power under the speakers rating.
I think it was because the calculations assumed the 28db input setting was being used on the amps, but I have been using the 1.2 volt setting assuming that matched the output of the Xover.
Is anyone willing to double cheak all the calculations for me?
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Old 15th February 2013, 08:22 PM   #14
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because you post good info, but of more value to other PA guys, I moved you to PA systems

hope you are ok with that


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Old 15th February 2013, 08:44 PM   #15
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Originally Posted by tinitus View Post
because you post good info, but of more value to other PA guys, I moved you to PA systems

hope you are ok with that


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Thats fine
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Old 15th February 2013, 08:54 PM   #16
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Originally Posted by 4pyros View Post
I think it was because the calculations assumed the 28db input setting was being used on the amps, but I have been using the 1.2 volt setting assuming that matched the output of the Xover.
Is anyone willing to double cheak all the calculations for me?
Andy,

Why do you keep looking for numerical calculations that won't address your loudspeaker problem?
As I wrote you the last time you "tenderized" your cones, simply run pink noise, back down your limiters until you see the cones don't exceed Xmax, done.

Well, "done" as long as the limiters are not set to "0" and LP to 20 Hz again .
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Old 15th February 2013, 09:07 PM   #17
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Quote:
Originally Posted by djk View Post
I had problems with Pyro tearing the Nomex voice-coil formers on Altec 288s right where they attach to the dome. The LF drivers never failed, but I never saw a situation as what you described (insanity).

I'll have to ask Bruce Knight from DB about that era, he lives locally.
DJK,

That might have been a glue problem aggravated by the pyro.

If you were like most of us at the time, you may have been using "protection" series capacitors, which removes the amplifier damping, allowing the diaphragm to move more freely when subjected to high SPL coming in from the outside.

Dave Rat was breaking TAD diaphragms just from the SPL of the adjacent woofers (while testing with the HF unpowered) until he removed the caps.
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Old 15th February 2013, 10:08 PM   #18
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"That might have been a glue problem aggravated by the pyro."

No, the Nomex tore, not the adhesive. The problem seemed to be the amplifier driving the diaphragm forward while the overpressure from the pyro drove the dome backwards, the dome seemed stretched as well. No cap in that setup, direct connected to a Crest 3501 IIRC. Switched to JBL 2441 after that, they didn't sound as good, but they held up better (under pyro). The former Nomex former is much heavier on the JBL than the Altec, but the HF on the large Altec is more like a good 1" driver.
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Old 16th February 2013, 04:16 PM   #19
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Quote:
Why do you keep looking for numerical calculations that won't address your loudspeaker problem?
Out of curiosity.

Quote:
simply run pink noise, back down your limiters until you see the cones don't exceed Xmax
I did not have the time or place to do that before. I will do it now.
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Old 12th March 2013, 02:47 PM   #20
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Originally Posted by 4pyros View Post
Can sound wave reflections from solid objects in frount of a set of subs, damage the speaker cones in tapped horns?


In other words, Should I worry about setting up tapped horn subs along the main road leading into a major casino with cars, trucks, and buses passing within feet in frount of the subs?

Andy
As long as you are not using delicate speakers such as ribbon tweeters you should be fine !
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