Was it Just Fletcher-Munson

[mikekars]

 

I attended a friend's outdoor gig Friday and was wondering about why it  sounded the way it  did at a relatively long distance from the stage.  FOH was about 90dB at 50-60 feet from the stage and it sounded great and well balanced there.  Also sounded good throughout most of the crowd area which was about 200 feet back and about 200 feet wide.  When I went back about 400 feet just about all the low and high frequency material was gone and all I could hear was sort of honky high mids.  Basically the female vocalist was coming through fairly clearly but not in a pleasant manner.

So was this just the way my ears react to  A,B, C type SPL curves?  That is, we are most sensitive a lower  SPL to the vocal range?  Or was there some other  factor at work here?  In any event the sound quality did not hold together much past 200' directly out.

 

This was an L-Acoutics rig with 4 Arcs tight packed per side on a 3' high stage and 2 SB28 dual 18 subs ground stacked each side.  processing was with a Lake controller using L-Acoustics recommended settings and amps were L-Acoustic brand.  This was a wide open grass field.    Sunny with a temp of 78 degrees and stable at 6:00PM with almost no wind. At 400 feet I was listening at standing height about 30 degress off center and it was blues /rock type music.

 

[agedhorse]

I can give a plausable answer based on generalities rather than the specific equipment here...

1. At 200 feet, you would have to factor in the HF attenuation due to accelerating losses of the HF while traveling through the air. Without running the calculations, and not knowing the humidity, it could easily approach >6dB. If the system is not behaving as a line source at this distance (due to whatever aspect), this could be made even worse.

2. At the lower frequencies, the system certainly would behave as a point source with the inverse square law yielding it's full effect.

3. At midrange frequencies (with this length source), it's most likely that the system would appear to operate (at a farther distance) with midrange frequencies, extening the reduced rolloff point by maybe 2d or 3d, making the midrange appear to roll off less relative to the lows and highs.

4. Without the low and high freq's at the same level, the masking effect is diminished and that coupled with the ear's increased relative sensitvity, would compound this effect.

 

[Pro Sound Guy]

http://www.prosoundweb.com/article/print/whats_the_delay_the_effects_of_weather_conditions_on_sound

 

[WynnD]

You really can't expect a perfect mix from every seat in an outdoor setting. Sounds like the sound guy did a decent job. I personally like listening to music 90-95 dbc. (Even indoors. A loud orchestra will get that loud indoors without a PA.) If you get a very good sound for 80% of the audience in that setting, you've done very well. Not everyone wants to hear rock and roll at 120+ dbc. And good music is still good music at 85 dbc. (And at that volume, people can actually hold conversations without shouting at each other. Every venue needs somewhere that people can talk with each other.)

[Dookietwo]

Could it have been much of the sound was coming from the stage/backline? I'm guessing the main speakers were high enough to get over the crowd but the sound from stage was ate up as the distance increased. FOH just 50 feet away the person mixing would have heard plenty of stage sound so maybe just a hint of everything and heavy on the vocals in the main pa would give just vocals 400 feet out.

Dookietwo

[Bobby1Note]

 

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mikekars wrote:

 

 

I attended a friend's outdoor gig Friday and

was wondering about why it  sounded the way it  did at a relatively long distance from the stage.  FOH was about 90dB at 50-60 feet from the stage and it sounded great and well balanced there.  Also sounded good throughout most of the crowd area which was about 200 feet back and about 200 feet wide.  When I went back about 400 feet just about all the low and high frequency material was gone and all I could hear was sort of honky high mids.  Basically the female vocalist was coming through fairly clearly but not in a pleasant manner.

 

So was this just the way my ears react to  A,B, C type SPL curves?  That is, we are most sensitive a lower  SPL to the vocal range?  Or was there some other  factor at work here?  In any event the sound quality did not hold together much past 200' directly out.

 

 

 

This was an L-Acoutics rig with 4 Arcs tight packed per side on a 3' high stage and 2 SB28 dual 18 subs ground stacked each side. 

processing was with a Lake controller using L-Acoustics recommended settings and amps were L-Acoustic brand.  This was a wide open grass field.    Sunny with a temp of 78 degrees and stable at 6:00PM with almost no wind. At 400 feet I was listening at standing height about 30 degress off center and it was blues /rock type music.

 

 

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Those L'Acoustics ARCS were the "wrong" speakers for the job. Those are constant-curvature arrays, and they're designed to be used in front of banked seating, such as bleachers or grandstands,,, not flat ground.

Constant-curvature arrays form an arc rather than a vertical array such as a J-hang array., and in a three-box hang for example,,, with 45-degree boxes, the lowest box in the hang would be aiming almost straight down, while the top box in the hang would be aiming horizontally. The centerline of the middle box, would be firing downward/forward at a 45 degree angle.

These types of arrays would typically be suspended from a roof, forward of and above the first row of banked seats, with the lowest box in the hang firing downward. The top box in the hang, would be aiming at the back rows at the top of the bleachers/grandstand. Those boxes would be hung roughly equidistant from the front and back rows. They don't "combine" like a typical vertical line-array, and that's why you got the volume drop-off at distance.

[mikekars]

Sorry - should have mentioned they were arrayed horizontally in a tight pack.  Not hung or stacked in a vertical manner.  With 4 of them that is supposed to result in a 90 degree wide by 60 degree high pattern.

 

[dboomer]

I think the simple answer is that speakers are not intended to work well at 200 feet let alone 400 feet.  That's what delay towers are for.