Tag Archives: Safety

The Biggest Scares In Audio

Spooky!

Please Remember:

The opinions expressed are mine only. These opinions do not necessarily reflect anybody else’s opinions. I do not own, operate, manage, or represent any band, venue, or company that I talk about, unless explicitly noted.

Want to use this image for something else? Great! Click it for the link to a high-res or resolution-independent version. This CC0 image was found here: https://pixabay.com/en/fantasy-spirit-nightmare-dream-2847724/

The following are very spooky for an audio human (or other show production crew) to hear. In no particular order:

“We brought our own wireless system. It’s super cool, because it has all four mics! Got it for $100 on Amazon.”

“We added a couple of openers.”

“I forgot to tell you that we have a percussion player.”

“We actually have two drumkits.”

“Everybody sings.”

“The drummer needs a mic for vocals.” (Some folks do this really well, but other people…)

“Could I have a mic? I do some screamo stuff on one song.”

“I just joined this loud rock band. I play acoustic guitar. There’s no pickup, so you’ll have to mic it.” Later: “Can you turn up my guitar in my monitor?”

“I just got this vocal processor today!”

“I’m almost done plugging in those big power cables. Haven’t done the green one yet – what’s that for?”

“I left that twist-lock on deck for you.” (While pointing to a power connector that is “hot,” but not connected to a distro box. I was almost guilty of this once, before I caught myself.)

“We can run a couple of circuits from the house.”

“Never worked with a chain hoist before.” (I’ve said this. There’s a first time for everything, you can’t get around that, but the first time a crew member is getting hands-on with flying gear is always a little stressful for everybody.)

“I’m pretty sure I can figure out the flyware for this rig.” (I’ve said this as well, in so many words.)

“Can you run down to [venueName]? Their regular monitor engineer can’t make it tonight.”

“The weather’s always good that weekend.”

“There’s a storm over the mountain, but it’ll miss us.”

“I wonder how far away that lightning strike was.” Alternate form: “I wonder how far away that light- ” *BOOOOM!*

“Can you guys make your setup smaller so we can have more room for dancing?” (To a six-piece band that has already been set up almost on top of one another.)

“Could you guys move your setup back a few feet?” (This is never said when making the move would be easy. Ever.)

“We’ll send out the check on Monday.” (Some folks are good for this. Other folks…)


Thoughts On Earplugs

They’re a good idea, and you don’t have to spend much to get good ones.

Please Remember:

The opinions expressed are mine only. These opinions do not necessarily reflect anybody else’s opinions. I do not own, operate, manage, or represent any band, venue, or company that I talk about, unless explicitly noted.

Want to use this image for something else? Great! Click it for the link to a high-res or resolution-independent version.

The Video

The Summary

You only get one pair of ears, so protect them with plugs. Don’t let anyone tell you not to do so. “Flat response” plugs can be both generic or custom fitted, with custom molds having a large advantage in overall comfort.


For The Love Of Trim Height

Trim height is very helpful if you can get it (and do it safely).

Please Remember:

The opinions expressed are mine only. These opinions do not necessarily reflect anybody else’s opinions. I do not own, operate, manage, or represent any band, venue, or company that I talk about, unless explicitly noted.

hightrimWant to use this image for something else? Great! Click it for the link to a high-res or resolution-independent version.

There are a couple of things I have to say before I dive into this:

1) I’m only going to get into the trim-height factors that, in my view, have a “snowball’s chance” of being helpful in a small-venue setting. Trim heights above 30 ft, with multiple, arrayable boxes in use can be a very handy thing…but they also involve venue size and PA deployment complexity that’s beyond the scope of this site.

2) The higher the trim height, the more dangerous things can be. I don’t say this to frighten anyone, but rather to call to mind the safety issues. Setting a box on a solid deck is very safe. Putting a box on a stand is less safe. Suspending a box is even less safe than putting the box on a stand. Higher trim heights, done with proper attention to weight limits, stability, and appropriate equipment, can be done “safely enough.” Not paying attention to those factors can result in someone being seriously injured or killed. Under NO circumstances should you compromise safety for an acoustical outcome. (I accept ZERO responsibility for anything you try, just to be clear.)

3) I’m using simplified drawings to make my points. They don’t exactly represent what sound does with real loudspeakers, real people, and a real room. However, the approximations are close enough to talk intelligently about what’s going on. (Just for a start, a box that claims 40-degree vertical coverage actually has a great deal of output beyond 40 degrees – as you have no doubt observed in real life.)

Anyway…

Trim height – that is, “gettin’ speakers in the air” – has real advantages. Done correctly, it lets you maximize the use of your loudspeaker’s output, minimize the amount that the PA “excites” the room’s acoustics, and use the acoustical impedance of your audience to an advantage.

Low Trim

lowtrim

We’ve all seen this at some point. An audio rig gets set up so that it’s sitting directly on the stage. It’s easy, cheap, and very safe. The loudspeakers are highly stable, and if one does get knocked over, it will probably hit someone’s foot or leg at low speed.

There are real problems, though. The biggest one is that the acoustical impedance of the audience is working against you. Electrical impedance is opposition to current flow. Acoustical impedance is the opposition to sound-pressure flow. Humans are pretty decent at absorbing sound, which means that firing a speaker directly into the front row is a waste of power. For all intents and purposes, the humans in the way of that audio are acoustical resistors, all lined up in series. A sonic “shadow” is cast by the people blocking the direct path of the loudspeaker’s output.

The upshot is that you can use up a ton of available output on trying to “push across” that absorption. Also, the front row gets a very different show than the listeners at the back. The folks in front are getting an experience with lots of direct sound, whereas pretty much everyone else is getting very different volume and a high proportion of indirect sound. The fictional venue I’ve constructed has a 20 ft ceiling, but it’s easy to imagine one with a much lower roof. Cut the ceiling height in half, and the direct sound that doesn’t hit the front row just hits the ceiling and starts bouncing around.

The thing is, we want to use our output to hit listeners, not boundaries.

Speakers On Sticks

The next step is to do what’s practical for most of us: We put boxes on tripods.

highertrim

This takes a little bit of doing, costs extra, and also requires some thought to safety. If a tripod falls over, someone could get hit in the head with a heavy piece of equipment; Due diligence is required.

Even so…immediately, you can see that the consistency of experience from audience-member to audience-member is greatly improved. Yes, the people in front do still generate acoustical shadowing, but the obstruction is far less pronounced. Pretty much everybody has a good chance at hearing the direct sound from the loudspeakers.

There is an acoustical downside, though. Getting the speakers in the air has increased the amount of output which is hitting the room’s boundaries. The reverberation we’ve introduced into our mix is rather greater, and we’re also firing output into a lot of nothing (before the output arrives at a wall or the ceiling, of course). If the ceiling is low, a lot of the loudspeakers’ energy is splattering against it. The situation is a waste of power, but at least it’s not as big a waste as trying to “blow through” the front row of spectators.

Just Hanging Around

What if we could get our boxes about 12 ft in the air, and angle them downwards?

hightrim

This is spendy and risky. You’ve got to have the proper rigging hardware, and whatever you rig to must be durable enough to handle the load. If the suspension system fails, a very heavy object could be moving very fast, and on a path towards somebody’s skull. The consequences for getting this wrong are high, so it shouldn’t be attempted without careful thought and professional help.

If the logistics are handled properly, then major advantages are conferred. Pretty much all of your output is being directed towards actual people. The audience obstruction of direct sound has been further reduced, meaning that there’s an even higher chance for everybody to be getting the same show. Our output is largely directed away from room boundaries, which means less indirect audio to reduce mix intelligibility.

This is also the configuration where the audience’s acoustical impedance works in our favor the most. A lot of the room reflections are likely to encounter a human’s absorption at an earlier time, further reducing reverberation intensity and the accompanying loss of intelligibility. Using our audience to soak up what we DON’T want, while letting them listen to what we want them to hear is a win-win.

A box that’s safely in the air and pointed in the right direction does more work that’s actually effective.