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[Michael Lawrence]

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?

For speech reinforcement / musical theater vocal systems / corporate the tonal response of the system tends to be rather flat. For music, overwhelmingly, the system response tends to have a significant amount of LF tilt. The two variables tend to be 1) how much (how many dB is 63 Hz above 1 kHz) and what is the "knee" behavior.

In the attached file, the purple trace is the "target" trace of one of the "big three" large format loudspeaker manufacturers. The white, pink and green are target traces I use for various A-level acts in large venues, and reflect the tonal preferences of those artists' mix engineers. The white curve is the preference of Volbeat FOH engineer Dennie Miller, and we also use it for Ghost, Miguel, Elfman, and a variety of other acts. When I use it at festivals I don't tend to get asked for changes.

Most medium and large format systems will exhibit a similar sort of tilt "out of the box", the exact specifics of how much are FOH preference more than anything. There are objective reasons to use more or less which I covered in my book and don't need to rehash here. Similarly, most large format systems aren't doing much if anything above 16 kHz, and realistically don't need to as the atmosphere is quite hostile to those frequencies at long distances so it's not typically considered a good use of your available headroom.

If you are interested in studying crossover behavior, that is best observed by measuring a single element in a controlled environment. Once the element response has been verified, you can deal with the combined response of the entire array to accomplish your desired tonality. I would certainly advise against tinkering with crossover filtering while measuring from the far field of an entire array, as you are changing the power sharing between the ways which should never be done in that context, and arguably not be done by the end user. If you wish to change the overall tonality of the source, use EQ, which avoids the issue.

[Art Hays]

This is great info and helps me understand what would be measured in terms of frequency in a good installed system.  Michael your book seems perfect to address this.  Thanks to everyone who posted!

[Brian Jojade]

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?

Prediction software is just that.  A prediction. It's never perfect. SO many things in a room will change the true result.  The prediction software just helps you get a fighting chance of getting it close.

There's no way to make a speaker system sound exactly the same in every seat.  As long as you're close enough to keep the meatbag in the seat happy, that's what matters.

People tend to fixate over high frequency response. Reality is, most adults have very little hearing above 15kHz. And in fact, hearing extreme high frequencies is only possible in more controlled environments.

In most scenarios, you could lowpass everything above 10kHz and most adult listeners would not notice the difference whatsoever.

[Bob Taylor]

For speech reinforcement / musical theater vocal systems / corporate the tonal response of the system tends to be rather flat. For music, overwhelmingly, the system response tends to have a significant amount of LF tilt. The two variables tend to be 1) how much (how many dB is 63 Hz above 1 kHz) and what is the "knee" behavior.

In the attached file, the purple trace is the "target" trace of one of the "big three" large format loudspeaker manufacturers. The white, pink and green are target traces I use for various A-level acts in large venues, and reflect the tonal preferences of those artists' mix engineers. The white curve is the preference of Volbeat FOH engineer Dennie Miller, and we also use it for Ghost, Miguel, Elfman, and a variety of other acts. When I use it at festivals I don't tend to get asked for changes.

Most medium and large format systems will exhibit a similar sort of tilt "out of the box", the exact specifics of how much are FOH preference more than anything. There are objective reasons to use more or less which I covered in my book and don't need to rehash here. Similarly, most large format systems aren't doing much if anything above 16 kHz, and realistically don't need to as the atmosphere is quite hostile to those frequencies at long distances so it's not typically considered a good use of your available headroom.

If you are interested in studying crossover behavior, that is best observed by measuring a single element in a controlled environment. Once the element response has been verified, you can deal with the combined response of the entire array to accomplish your desired tonality. I would certainly advise against tinkering with crossover filtering while measuring from the far field of an entire array, as you are changing the power sharing between the ways which should never be done in that context, and arguably not be done by the end user. If you wish to change the overall tonality of the source, use EQ, which avoids the issue.

So that Purple Trace explains a lot about why it seems I need to pull so much Low Mid out of the Mics when I mix at my new church. They have a VRX A8 rig hung in the Worship Centre.

Question I have, Are all these brands of Line Arrays using the same kind of 3dB per octave boost below 1kHz?

I have always set up my portable PA that uses Point Source speakers as Flat to about 1.5kHz and then let it fall off at about 2 dB per octave above that. I do boost the gain on the Sub channel using an asymmetrical crossover so I can get +8 dB at about 80Hz and down without affecting above 100 Hz. (using Aux Fed Subs on my mixer) Seems doing it this way I don't need to do a lot of channel EQ. On this Line Array stuff I need more channel EQ than I'm used to doing and always feel I'm doing something wrong. Trying to learn and understand what these Manufacturers are doing to me that I have no control over.

Bob T

[Tim McCulloch]

So that Purple Trace explains a lot about why it seems I need to pull so much Low Mid out of the Mics when I mix at my new church. They have a VRX A8 rig hung in the Worship Centre.

Question I have, Are all these brands of Line Arrays using the same kind of 3dB per octave boost below 1kHz?

I have always set up my portable PA that uses Point Source speakers as Flat to about 1.5kHz and then let it fall off at about 2 dB per octave above that. I do boost the gain on the Sub channel using an asymmetrical crossover so I can get +8 dB at about 80Hz and down without affecting above 100 Hz. (using Aux Fed Subs on my mixer) Seems doing it this way I don't need to do a lot of channel EQ. On this Line Array stuff I need more channel EQ than I'm used to doing and always feel I'm doing something wrong. Trying to learn and understand what these Manufacturers are doing to me that I have no control over.

Bob T

The longer the line the more LF coupling.  This is a known physics thing, Bob, and current manufacturer software includes tools to compensate for this in current products.  Before, we "Smaarty-pants" folks would use filters in the system DSP.  Today we can apply the EQ tool in prediction software and see an estimation of the likely result, make whatever tweaks, and then "push" those settings to the DSP (stand alone or internal to amplifiers) and then measure/audition the results.

Regarding the system you are now operating... feed it some pink noise (not airplane level) and walk the coverage area, left to right, upstage/downstage, FOH and where the $$ donors are at services, etc.  You'll hear lots of things, trust me! 

The repeat with some recorded program.  You'll find other things... but all of them will be better revealed with pink (unless it's Barbie Movie pink, which is a whole 'nuther thing).

Have fun, good luck.

Tim Mc

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