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Old 14th February 2013, 02:11 PM   #1
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Default Reflections and Tapped Horns

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

Last edited by 4pyros; 14th February 2013 at 08:00 PM.
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Old 14th February 2013, 02:30 PM   #2
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I wouldn't worry too much about it. As a truck passes by, the pressure wave you feel is such a low frequency that the TH would act as a short-circuit: it'd push on both sides of the cone at pretty much the same time, so the forces would pretty much cancel.
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Old 14th February 2013, 04:15 PM   #3
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Quote:
the pressure wave you feel is such a low frequency that the TH would act as a short-circuit
Sorry Chris I do not under stand what you mean by "such a low frequency" would that not make the sound wave longer and more susceptible to reflections?
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Old 14th February 2013, 05:29 PM   #4
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When driven below the lowest tuning, tapped horns provide almost no resistance to airflow, right?

It makes sense (to me, at least) that, if it was to be excited externally, it would have similar tuning properties. ie, if the TH has a lowest tuning at 30Hz, an external source of 20Hz would excite both sides of the cone pretty much at the same time, in much the same way as the driver itself would run out of excursion at 20Hz pretty quick: at those wavelengths, the cabinet disappears.

HTH

Chris

PS - I may have it completely wrong, and would happily admit that if anyone comes along with a better answer.
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Old 14th February 2013, 05:40 PM   #5
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Quote:
Originally Posted by 4pyros View Post
Can sound wave reflections off nearby solid objects 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 of the subs?

Andy
Andy,

Passing vehicles create a temporary boundary that can increase level, but will not cause any damage.
If you park a bus alongside your stack, it will increase forward output more than 3 dB.
Did you ever determine what voltage to limit your amplifiers to prevent overexcursion of your 3015LFs?

Art
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Old 14th February 2013, 08:07 PM   #6
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OK I rephrased my question. To say the vehicles are passing right in front of the speakers not passing along side them.
Meaning the sound wave is coming back to the cab from the front.
Does that make a differance?

Last edited by 4pyros; 14th February 2013 at 08:14 PM.
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Old 14th February 2013, 08:14 PM   #7
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Originally Posted by weltersys View Post
Andy,

Passing vehicles create a temporary boundary that can increase level, but will not cause any damage.
If you park a bus alongside your stack, it will increase forward output more than 3 dB.
Did you ever determine what voltage to limit your amplifiers to prevent overexcursion of your 3015LFs?

Art
Walt;
I started out the year with the limiter set to -8db and low end set to 40hz.
Unfortunately sometime during the year the settings ended up back at default. 0db limit and 20hz low pass.
The cones are damaged again but not as bad as last time.
I still need to physically check excursion. I may be able to do that tomorrow.
Andy
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Old 14th February 2013, 08:15 PM   #8
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Originally Posted by 4pyros View Post
OK I rephrased my question. It say the vehicles are passing right in front of the speakers not passing along side them.
Meaning the sound wave is coming back to the cab from the front.
Does that make a differance?
No.
Neither will people standing in front of the cabinets.
To much excursion from driving the speakers too hard will damage cones, as you have already found.

Explosives in close proximity to horn loaded speakers can damage cones, but it has to be really loud, like 180 dB, and really close, like a flash pot on top of the cabinet.

Art
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Old 15th February 2013, 07:42 AM   #9
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Pyro is more likely to blow HF drivers.
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Old 15th February 2013, 01:15 PM   #10
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i think the pressure of a passing truck is negligible,compared to the pressure inside the th @ full power.
a formula 1 car or nascar,dragster ect, maybe,if they get close enough.
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Last edited by epa; 15th February 2013 at 01:17 PM.
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