Author Topic: PA tuning  (Read 8669 times)

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freddypc

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PA tuning
« on: March 02, 2012, 10:57 »
Hi, in your opinion, how is the best signal (sweep tone or pink noise) to eq PA system parts?
I generally capture many impulse response (and relative FFT curve) in different place (on axys, out of axys, near, far), then I create an average curve and work with the eq to adjust the sound. The same for every part of the system (main, front, infill, side, delay). Then I align in phase the different system and capture again different curve in different place for the final optimization.
I've seen many people do the same work, someone with pink noise, other with sweep test sound.
In many articles and book I can't find a suggestion about this.

Please, write your opinions!!

Thanks

TomyN

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Re: PA tuning
« Reply #1 on: April 27, 2012, 23:40 »
Hi,

for the standard tasks in the MAT module I prefer pink noise, because its easy to use. In the most current version I use bandpass noise when I adjust subwoofers.

When doing room-acoustic measurements, I use a sweep, because it creates a real fine impulse-response.

Once I had to tune the PA while the band was playing, using their music. I was pleased by the result, because it contains also some of the 'stage noise'. But I prefer haven the system ready when the musicans arrive.

Tomy
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Jeffsco

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Re: PA tuning
« Reply #2 on: April 30, 2012, 16:31 »
TomyN: Could you differentiate between Roon/Acoustic measurements and "standard Tasks"? Does standard tasks include the basic alignment between tops and bottoms? Does Room-acoustic measurments include the PA in the room? or are you talking about more of an installed system type of use where you are determining the reverb decay time and speech intelligibility ratings and such?

TomyN

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Re: PA tuning
« Reply #3 on: April 30, 2012, 19:34 »
Well, there are two approaches to acoustic measurement.

The first is the more scientific, which is based on the impulse-response. This developed for a long time, because the measurement of impuse-responses has been possible long before computers occured.
So (nearly) all scientific work related to room-acoustics is somewhat based on the impulse-response. Some of the room acoustic parameters are RT60, STI, clarity and so on.
The 'traditonal' workflow is to capture some impulse-responses and to perform the post-processing afterwards, often even not at the same location.
All of this targets to a room-acoustic description of the room. The description can focus on the pure room or on the room 'triggered' by the build in loudspeaker-system. The frequency - response is not of primary interest in this measurements, and there is not much which you can do immediately to alter/improve the behavior of the room. The only thing you can try is to change the 'triggering' of the room by using high directional speakers (and to aim them correctly).

On the other hand there is the Dual-FFT measurement, which is (in the scientific point of view) a young methode.
This is a more practical approach, because it targets mainly towards the frequency response, both in amplitude and in phase (which is important, because the phase tells us about the behavior in time), the results are shown immediately and the measurement runs continously. This makes the Dual-FFT (which is the MAT-module in SATlive) the prefered measurement for the setup of portable sound systems, where you need the information right now.

In my opinion the 'standard tasks' in the acoustic measurement related to the use of a PA system are:

A) Time alignment between different speakers which arrive at the same point in the audience with nearly the same level.

B) Measurement of the frequency response and display of a 'quality criteria' to decide where and how to use an equalizer.

Setting a delay-line is part of A, also is adjusting the arrival time of High/mid and subwoofer. Setup of directional bass-arrays involves both tasks, as you need to adapt the frequency-response and the delay.

Tomy
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Jeffsco

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Re: PA tuning
« Reply #4 on: April 30, 2012, 20:25 »
Thanks Tomy. Good to know. I like the way it is broken down.