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[Art Hays]

Working with a rather old installed system (circa 2012).  Martin DX2 processor and labgruppen C28:4 amps.  Don't know who makes the line array or subs.  Mono hang in the middle probably intended more for theater.  Four fills hanging in ceiling- two at front sides and two more 3/4 way back.   Probably intended to fill gaps from mono hang.  Auditorium seats around 1100.  Two amp channels for highs and two for mids (don't know if the top array speakers and bottoms are on separate channels but would assume).  One larger amp for hanging subs.

With all EQ flat measured this response at FOH, which is 2/3 the way back in center.  One curve is just the mids and one the highs.  Subs and fills not on.

I can change the levels on the amps to make the high bump to be same height as the mid bump.  But I'm curious why the response doesn't go up to 18 or 20k?

Please forgive not using SMAART yet :-).

[Ivan Beaver]

I can change the levels on the amps to make the high bump to be same height as the mid bump.  But I'm curious why the response doesn't go up to 18 or 20k?

Please forgive not using SMAART yet :-).

How many systems (of any type) have you measured at FOH that go up to 20K?  Without a crapload of boosting

[brian maddox]

How many systems (of any type) have you measured at FOH that go up to 20K?  Without a crapload of boosting

And the loaded followup question, why would you need/want it to?

[flamesuit on]

[Jim McKeveny]

Paul Klipsch: "We live in the midrange".

[Art Hays]

I don't have experience with installed sound in this size auditorium so I was wondering if something was blown or not working.  The highs in the array are 3db down at 12.5k.  Even the four fill speakers, way off axis at FOH, are 3db down at 18k.

[Art Welter]

I don't have experience with installed sound in this size auditorium so I was wondering if something was blown or not working. 

Art,

In addition to the usual 6dB loss per doubling of distance, high frequencies are absorbed depending on the damping as a function of frequency, temperature, and humidity.
The mono hang's further distance compared to the fills may account for the HF loss.

http://www.sengpielaudio.com/calculator-air.htm

The attached chart with temperature at 75F and  35%RH shows 20kHz reduced by 18dB at 100 ft (around 31 meters) compared to 8.5dB at 12.5kHz, 5.7dB at 10Khz, and only 1.6dB loss at 5kHz.

Art

[Riley Casey]

It helps to remember that all those pretty frequency response graphs on the speaker makers product sheets are measured at one meter, with the measurement position tweaked for best possible measurement 'beauty'. After all that the curves are smoothed to third octave for public consumption.  Don't take any published specs as representative of real world performance.

[Art Hays]

Thanks so much I'm learning a lot.  I've seen the prediction software plots from the line array companies showing sound levels at every seat.  I just assumed the frequency response was flat at every seat too. 

In a 1000 seat auditorium what is a good target goal for frequency response- flat up to what frequency?

[Adam Kane]

Working with a rather old installed system (circa 2012).  Martin DX2 processor and labgruppen C28:4 amps.  Don't know who makes the line array or subs.  Mono hang in the middle probably intended more for theater.  Four fills hanging in ceiling- two at front sides and two more 3/4 way back.   Probably intended to fill gaps from mono hang.  Auditorium seats around 1100.  Two amp channels for highs and two for mids (don't know if the top array speakers and bottoms are on separate channels but would assume).  One larger amp for hanging subs.

With all EQ flat measured this response at FOH, which is 2/3 the way back in center.  One curve is just the mids and one the highs.  Subs and fills not on.

I can change the levels on the amps to make the high bump to be same height as the mid bump.  But I'm curious why the response doesn't go up to 18 or 20k?

Please forgive not using SMAART yet :-).

My first question would be: How does it sound?

Between air absorption, and other interplay with surfaces in the room and seating, it would be pretty tough to get a ruler flat measurement to 20K with nearly any system without a massive amount of EQ...and I'm not sure it would sound so fantastic.

[Jim McKeveny]

- flat up to what frequency?

You're really poking the bear here, Art. What is "flat"? And from what frequency? And what SPL? Etc, etc,...

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