Hey PA gang!

[Dissident Sound]

Before IPods

i had a Sony MiniDisc 🙂

 

[ThatSoundsGood]

The article ended saying: "The future will bring improved transducer technology to provide the output we need to provide a full, high-level, very-high-frequency listening experience out to a distance of 200 to 250 feet, with an acceptable, although lower, experience to 300 feet. Beyond that distance, air propagation losses are very significant, and additional delay clusters will continue to be required for full fidelity."

I've heard some good PA's throw high end about 500' pretty well. There's always a little bit of high end loss but on a good day I've heard some things that seem to defy physics. But yeah, we like to keep it under 300'. But that's really far if you think about it. There are often many other problems when you're dealing with 300'.

There has been no improvement evident in over 100 years of transducer technology advancement that could compensate for air absorption VHF losses.
I don't expect any breakthroughs until teleportation becomes commonplace.

We certainly have much better drivers now and having amplifiers and software that compensates for these problems along with drivers that can handle the compensation, we have much better technology so I don't really agree with this.

As far as delay systems, they can only be aligned to a single position, under a specific environmental condition which is subject to constant change, and are too expensive to deploy for around an octave that most of the audience won't miss.

We deploy successful delay systems in stadiums al of the time. Yes, they can only be set to one delay time, but properly placed towers with delays and proper use of EQ can get them to sound really good in most spots. It's usually not a total disaster unless there isn't enough time to get it all done properly.

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They will continue to used, but won't solve the VHF problem.

The delay towers don't solve the problem but they make it a lot better. We have more problems with reflections off of roofs and other structures than we do with high frequency loss.

 

[ThatSoundsGood]

The VHF is always a limiting factor at distance due to atmospheric losses in addition to inverse distance losses. At a football field distance, the SPL delivered above 10kHz may drop between 10 and 60dB compared to frequencies below 1200Hz, the typical lower range of a high frequency driver in a line array.

10Khz and above are not very important in the grand scheme of the frequency response. But again, we have ways to deal with it.

Obviously, the high frequency system transducers can't handle several orders of magnitude more power, so we live with the losses.
https://sengpielaudio.com/calculator-air.htm
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As evident in the above calculations, humidity and temperature make huge variations in losses.
When I first moved to the high, dry desert conditions of New Mexico from the humid summers in Minnesota, thought I'd lost my hearing when I started mixing again, the VHF was literally less than half as loud at 100 feet than I was used to.

Yeah man. It's pretty wild what temperature and humidity can do. But really, the wind is the worst factor. Have you ever mixed a show in the wind? It's a nightmare for obvious reasons.

I remember the first time I'd actually seen dozens of 2x18" subs used in end-fire arrays was at Tingley Coliseum, in Albuquerque on 3/11/2006 when an old friend invited me to see KoRn, who he was production managing at the time.
Shortly in to their set, the FOH sound power died.
We first ran to the sound power distribution expecting to find a tripped breaker, but Wally found an entire phase dead. He checked the 4/0 power cables back to the disconnect and found one of the 400 amp 3 phase mains fuses had blown.
Had to track down the house electrician to get a replacement fuse, seemed like forever, though probably around 15 minutes. Definite vibe kill...

In the interim, the sound guys blamed the light guys (who had a separate 600 amp 120/208 three phase service) for the power outage because a 30 amp projector had been plugged into the sound power distribution.

Always blame the lighting guys. Unless there are video guys around. Blame them.
But really, if a lighting guy plugged a 30 amp projector into my distro on the road, he would regret it and never make the same mistake twice. But that generally doesn't happen as we all know that we use our own power.

 

[wg_ski]

Before IPods, I used to set up the big gear next to the lake so I could enjoy Jimmy Buffett while water skiing.

Back when I used to ski, I brought out my medium format PA (full stack of original lab horns on the bottom) to do ski shows and tournaments. Set it up close to the highway facing the lake, put everyone in the far field. Beat the pants off setting up cute little 12 or 15” 2 ways on sticks every hundred feet for a quarter mile. Clear sound with actual bass the skiers could hear.

 

[weltersys]

Yeah man. It's pretty wild what temperature and humidity can do. But really, the wind is the worst factor. Have you ever mixed a show in the wind? It's a nightmare for obvious reasons.

One high desert blues fest the wind was blowing so hard towards the stage that the PA sounded like it went through the classic Roland "Jet Phaser" stomp box.
Knowing the winds would be blowing dirt like crazy, had made clear Plexiglass covers to keep it out of the new Midas console faders, the covers blew off several times before I gave up on that idea.

The promoter came up and asked if he thought we should call the show off before the final band due to the wind, I replied "if any mic stands blow over, lets pack it in".
Half of the audience had already left by then, tired of the sandstorm and chasing down shade umbrellas.

A few minutes after the last act went on, the PA sound improved after a particularly strong gust.
I looked up from the board and saw the stage right stack had been blown off the sound wing- less phase problems from a single source..

After the show I blew all the mic wind screens out with an air compressor, each one created a mini dust storm.

Art

 

[ThatSoundsGood]

Yeah, I've seen 5000 pound PA systems swinging and twisting in the wind. It sounds like there's a chorus pedal on everything. It's one thing for the motors to hold static weight but dynamic weight is a different beast. There are a lot more safety protocols these days after we've had some stage collapses.

 

[weltersys]

In 2019, Dave Rat introduced his wind clamps on the delay towers at Cochella to reduce the swinging and twisting:

Nice feature, but the wind gradients still do plenty of "chorusing" whenever there are multiple high frequency sources.

Doesn't look as disturbing...

 

[ThatSoundsGood]

Those clamps look really cool and could definitely help it from swinging around. The wind still causes a lot of problems but it is nice to not have the PA also swinging around.....for obvious reasons. I will be at Coachella in a few weeks so I will check to see if they're still using them.