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Author Topic: Ever been surprised by your rig?  (Read 2101 times)

Chris Grimshaw

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Ever been surprised by your rig?
« on: July 05, 2017, 08:27:23 am »

I agreed to do an event without fully realising the size of the venue. A clever move on my part, to be sure.

The PA system I run is pretty reasonable, with 4x 15" ported subs loaded with Faital Pro 15HP1060 drivers, and 2x 2x10" tops with FP 10FH520 and 18Sound ND1460 drivers on a 90x40 horn. Tri-amped with Behringer iNukes, around 1KW for each 15" and 10" driver, and 300w for the HF. A fairly solid small-format setup.

You can imagine what went through my mind, then, when the venue was a rugby stadium. For those of you based in the Land of the Free, rugby is like your football, but with less padding and more blood.

Anyway, I was told by email we were firing along the length of the pitch, so I was planning delay lines (some 12" coaxial monitors), which would go nicely where the covered seating is, about half-way down the pitch. On the day, I was told it would be across the pitch, and they wanted the setup arranged in a way that it would've been awkward to deploy any delays.

I was worried while I was cabling everything. Pushed the fader, and this happened:

https://www.youtube.com/watch?v=ZXuV-Cl0hmI

At that position, the SPL meter was reading 85dB, C-weighted, slow response, at somewhere around 250' from the speakers.
The PA is just about visible, and this was just about tickling the limiters.

I was grinning for the rest of the day.

Chris
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Steve Alves

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Re: Ever been surprised by your rig?
« Reply #1 on: July 05, 2017, 09:42:37 am »

It is always amazing what getting them up in the air does.
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Steven Alves
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Art Welter

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Re: Ever been surprised by your rig?
« Reply #2 on: July 05, 2017, 12:27:20 pm »


At that position, the SPL meter was reading 85dB, C-weighted, slow response, at somewhere around 250' from the speakers.
The PA is just about visible, and this was just about tickling the limiters.

I was grinning for the rest of the day.

Chris
Chris,

Now you appreciate the inverse distance law works, it is also easy to work out each stack only had to do around 117 dBC slow at one meter to achieve that level down "power alley".

Physics is Phun!

Cheers,

Art
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David Buckley

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Re: Ever been surprised by your rig?
« Reply #3 on: July 05, 2017, 05:23:17 pm »

... the venue was a rugby stadium. For those of you based in the Land of the Free, rugby is like your football, but with less padding and more blood.

You are aware that The Yanks are the current rugby Olympic champions...?
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Chris Grimshaw

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Re: Ever been surprised by your rig?
« Reply #4 on: July 06, 2017, 04:30:52 am »

You are aware that The Yanks are the current rugby Olympic champions...?

Not at all. I don't follow sports much, just thought some clarification might be needed.


Art, 117dB C-slow doesn't sound like much!
Analysing the track, though, and it looks like the RMS level (according to Audacity) is around 18dB down from the peaks. If the meter set to "slow" tracks Audacity's RMS level reasonably closely, then it's possible the stacks were touching the limiters at about 135dB peaks, give-or-take a few dB to account for C-weighting and the fact that the last dB or two was lost by going into the limiters.

That'll do for me, anyway.

I did take the MF-HF crossover up from 800Hz to 1.2kHz for that particular event. 800Hz gives nicer polars, but I'd much prefer it if the HF drivers survived the gig.

Chris
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Ivan Beaver

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Re: Ever been surprised by your rig?
« Reply #5 on: July 06, 2017, 08:03:18 am »



Now you appreciate the inverse distance law works,
Physics is Phun!

Cheers,

Art
Inverse square law can be your friend or foe-depending on how it is looked at and from what perspective.
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Ivan Beaver
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g'bye, Dick Rees

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Re: Ever been surprised by your rig?
« Reply #6 on: July 06, 2017, 01:54:42 pm »

It's not the rig that is surprising so much as what you can hear when the ambient noise level goes down below 40dB.

On 9/12 when the local airport (MSP) was shut down and the freeways were almost deserted, it was like being back on the farm in Iowa in the 1950's.  The loudest thing was the birds sining...
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Don T. Williams

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Re: Ever been surprised by your rig?
« Reply #7 on: July 06, 2017, 02:11:35 pm »

It's not the rig that is surprising so much as what you can hear when the ambient noise level goes down below 40dB.

On 9/12 when the local airport (MSP) was shut down and the freeways were almost deserted, it was like being back on the farm in Iowa in the 1950's.  The loudest thing was the birds sining...

The birds were sining rather loudly I assume!
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g'bye, Dick Rees

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Re: Ever been surprised by your rig?
« Reply #8 on: July 06, 2017, 06:56:00 pm »

The birds were sining rather loudly I assume!

Sorry.  Right letters, wrong order.

Singin'...

I had the "g" in the wrong spot.  Typical male...
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Chris Hindle

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Re: Ever been surprised by your rig?
« Reply #9 on: July 07, 2017, 11:47:04 am »

It's not the rig that is surprising so much as what you can hear when the ambient noise level goes down below 40dB.

On 9/12 when the local airport (MSP) was shut down and the freeways were almost deserted, it was like being back on the farm in Iowa in the 1950's.  The loudest thing was the birds sining...
My office is beside Montreal's international airport. Both main runways were in use that day.
At one point I looked up, and i could see a string of 20 sets of landing lights for each runway. No idea on how many were circling out of my sight.
Don't know where they all got parked, but it was a busy day at the old airport. At least up here, no one had the bad manners to park a plane in a building.
Chris.
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Luke Geis

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Re: Ever been surprised by your rig?
« Reply #10 on: July 07, 2017, 01:21:20 pm »

Less is truly more.

It is not the size of the dog in the fight, but more the size of the fight in the dog.

If there was a such thing as a 3" speaker that could produce linear output at 130db from 50hz to 20khz. it would be every bit as good as a 12" or bigger counterpart that produced the same output. Many forget that it the size of the system has nothing to do with its coverage and output.

In a perfect world if you had two speakers that coupled together entirely, you would only gain 3db. This is such a small gain that it will not make or break your day. If you need the coverage, that is one thing, but if you only need to acquire X SPL level at X distance over X area, then any single speaker that can meet those needs will do just fine.
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Ivan Beaver

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Re: Ever been surprised by your rig?
« Reply #11 on: July 07, 2017, 04:54:22 pm »



In a perfect world if you had two speakers that coupled together entirely, you would only gain 3db.
Actually the gain is 6dB.  You get 3dB from double the power capacity, and another 3dB from the coupling to the air.

This happens with subs that are close together all the time.
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Art Welter

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Re: Ever been surprised by your rig?
« Reply #12 on: July 07, 2017, 05:33:51 pm »

Art, 117dB C-slow doesn't sound like much!
Analysing the track, though, and it looks like the RMS level (according to Audacity) is around 18dB down from the peaks. If the meter set to "slow" tracks Audacity's RMS level reasonably closely, then it's possible the stacks were touching the limiters at about 135dB peaks, give-or-take a few dB to account for C-weighting and the fact that the last dB or two was lost by going into the limiters.

That'll do for me, anyway.

I did take the MF-HF crossover up from 800Hz to 1.2kHz for that particular event. 800Hz gives nicer polars, but I'd much prefer it if the HF drivers survived the gig.

Chris
Chris,
The "slow" rating really ignores the peaks, 117 dBC slow as you find probably is 135 dB peak. "Sultans of Swing" was one of the first CD releases, back when recordings were made with lots of dynamic range, taking advantage of the much wider range compared to vinyl or cassette tape. Funny how with over 100 dB dynamic range available, so many releases now use only 6-10 dB.

Using a short selection of music for a portion of my epic HF driver evaluation, I used Smaart's impulse response to test the driver's peak output - but found I had to video tape the screen to find the peak value, as it would go by too fast for my eye to register it. Without reviewing the video, I would have reported the output around 6 dB less. Sure wished the impulse response had a "peak hold" function...

Art
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Russ Davis

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Re: Ever been surprised by your rig?
« Reply #13 on: July 07, 2017, 05:58:17 pm »

I had the "g" in the wrong spot.  Typical male...

The "G spot" can be found easily enough.  It's worth the search.
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Stu McDoniel

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Re: Ever been surprised by your rig?
« Reply #14 on: July 09, 2017, 08:44:25 am »

I agreed to do an event without fully realising the size of the venue. A clever move on my part, to be sure.

The PA system I run is pretty reasonable, with 4x 15" ported subs loaded with Faital Pro 15HP1060 drivers, and 2x 2x10" tops with FP 10FH520 and 18Sound ND1460 drivers on a 90x40 horn. Tri-amped with Behringer iNukes, around 1KW for each 15" and 10" driver, and 300w for the HF. A fairly solid small-format setup.

You can imagine what went through my mind, then, when the venue was a rugby stadium. For those of you based in the Land of the Free, rugby is like your football, but with less padding and more blood.

Anyway, I was told by email we were firing along the length of the pitch, so I was planning delay lines (some 12" coaxial monitors), which would go nicely where the covered seating is, about half-way down the pitch. On the day, I was told it would be across the pitch, and they wanted the setup arranged in a way that it would've been awkward to deploy any delays.

I was worried while I was cabling everything. Pushed the fader, and this happened:

https://www.youtube.com/watch?v=ZXuV-Cl0hmI

At that position, the SPL meter was reading 85dB, C-weighted, slow response, at somewhere around 250' from the speakers.
The PA is just about visible, and this was just about tickling the limiters.

I was grinning for the rest of the day.

Chris
Those are all some really sweet components you have in those boxes ;)
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Chris Grimshaw

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Re: Ever been surprised by your rig?
« Reply #15 on: July 13, 2017, 03:41:18 am »

Those are all some really sweet components you have in those boxes ;)

Speakers are the weak link in the chain, so I try to give them as much advantage as I can. After all, we're still waving bits of cardboard (or titanium) around with magnets.

I'd really like to try a pair of those BMS coaxial compression drivers, but the 18Sound ones do the job for now.

Chris
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Steve M Smith

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Re: Ever been surprised by your rig?
« Reply #16 on: July 13, 2017, 07:02:31 am »

Speakers are the weak link in the chain, so I try to give them as much advantage as I can. After all, we're still waving bits of cardboard (or titanium) around with magnets.

I like things like this.  It doesn't matter how far technology has progressed, there are some things we are still doing the same way after 100 years.

Another one is the fact that you can access access all the information on the internet and contact anyone in the world using a pair of wires from your house to the exchange, initially designed for telegraphy along railway lines.


Steve.
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