Tag Archives: SPL

Hitting The Far Seats

A few solutions to the “even coverage” problem, as it relates to distance.

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.

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This article, like the one before it, isn’t really “small venue” in nature. However, I think it’s good to spend time on audio concepts which small-venue folk might still run across. I’m certainly not “big-time,” but I still do the occasional show that involves more people and space. I (like you) really don’t need to get engaged with a detailed discussion regarding an enormous system that I probably won’t ever get my hands on, but the fundamentals of covering the people sitting in the back are still valuable tools.

This article is also very much a follow up to the piece linked above. Via that lens, you can view it as a discussion of what the viable options are for solving the difficulties I ran into.

So…

The way that you get “throw” to the farthest audience members is dependent upon the overall PA deployment strategy you’re using. Deployment strategies are dependent upon the gear in question being appropriate for that strategy, of course; You can’t choose to deploy a bunch of point-source boxes as a line-array and have it work out very well. (Some have tried. Some have thought it was okay. I don’t feel comfortable recommending it.)

Option 1: Single Arrival, “Point Source” Flavor

You can build a tall stack or hang an array with built-in, non-changeable angles, but both cases use the same idea: Any given audience member should really only hear one box (per side) at a time. Getting the kind of directivity necessary for that to be strictly true is quite a challenge at lower frequencies, so the ideal tends to not be reached. Nevertheless, this method remains viable.

I’ve termed this deployment flavor as “single arrival” because all sound essentially originates at the same distance from any given audience member. In other words, all the PA loudspeakers for each “side” are clustered as closely as is practical. The boxes meant to be heard up close are run at a significantly lower level than the boxes meant to cover the far-field. A person standing 50 feet from the stage might be hearing a loudspeaker making 120 dB SPL at 3 feet, whereas the patrons sitting 150 feet away would be hearing a different box – possibly stacked atop the first speaker – making 130 dB SPL at 3 feet. As such, the close-range listener is getting about 96 dB SPL, and the far-field audience member also hears a show at roughly 96 dB SPL.

This solution is relatively simple in some respects, though it requires the capability of “zone” tuning, as well as loudspeakers capable of high-output and high directivity. (You don’t want the up-close audience to get cooked by the loudspeaker that’s making a ton of noise for the long-distance people.)

Option 2: Single Arrival, Line-Array Flavor

As in the point source flavor, you have one array deployed “per side,” with each individual box as close to the other boxes as is achievable. The difference is that an honest-to-goodness line-array is meant to work by the audible combination of multiple loudspeakers. At very close distances, it may be possible to only truly hear a small part of the line, and this does help in keeping the nearby listeners from having their faces ripped off. However, the overall idea is to create a radiation pattern that resembles a section of a cylinder. (Perfect achievement of such a pattern isn’t really feasible.) This is in contrast to point-source systems, where the pattern tends towards a section of a sphere.

As is the case in many areas of life, everything comes down to surface area. A sphere’s surface area is 4*pi*radius^2, whereas the lateral surface area of a cylinder is 2*pi*radius*height. The perceived intensity of sound is the audible radiation spread across the surface area of the radiation geometry. More surface area means less intensity.

To keep the calculations manageable, I’ll have to simplify from sections of shapes to entire shapes. Even so, some comparisons can be made: At a distance of 150 feet, the sound power radiating in a spherical pattern is spread over a surface area of 282,743 square feet. For a 10-foot high cylinder, the surface area is 9424 square feet.

For the sphere, 4 watts of sound power (NOT electrical power!) means that a listener at the 150 foot radius gets a show that’s about 71 dB. For the cylinder, the listener at 100 feet should be getting about 86 dB. At the close-range distance of 50 feet, the cylindrical radiation pattern results in a sound level of 91 dB, whereas a spherical pattern gets 81 dB.

Putting aside for the moment that I’m assuming ideal and mathematically easy conditions, the line-array has a clear advantage in terms of consistency (level difference in the near and far fields) without a lot of work at tuning individual boxes. At the same time, it might not be quite as easily customizable as some point-source configurations, and a real line-source capable of rock-n-roll volume involves a good number of relatively expensive elements. Plus, a real line has to be flown, and with generous trim height as well.

Option 3: Multiple Arrival, Any Flavor

This is otherwise known as “delays.” At some convenient point away from the main PA system, a supplementary PA is set. The signal to that supplementary PA is made to be late, such that the far system aligns pleasingly with the sound from the main system. The hope is that most people will overwhelmingly hear one system over the other.

The point with this solution is to run everything more quietly and more evenly by making sure that no audience member is truly in the deep distance. If each PA only has to cover a distance of 75 feet, then an SPL of 90 dB at that distance requires 118 dB at 3 feet.

The upside to this approach is that the systems don’t have to individually be as powerful, nor do they strictly need to have high-directivity (although it’s quite helpful in keeping the two PA systems separate for the listeners behind the delays). The downside is that it requires more space and more rigging – whether actual rigging or just loudspeakers raised on poles, stacks, or platforms. Additionally, you have to deal with more signal and/ or power runs, possibly in difficult or high-traffic areas. It also requires careful tuning of the delay time to work properly, and even then, being behind or to the side of the delays causes the solution to be invalid. In such a condition where both systems are quite audible, the coherence of the reproduced audio suffers tremendously.


If I end up trying the Gallivan show again, I think I’ll go with delays. I don’t have the logistical resources to handle big, high-output point-source boxes or a real array. I can, on the other hand, find a way to boxes up on sticks with delay applied. I can’t say that I’m happy about the potential coherence issues, but everything in audio is a compromise in some way.


What Went Wrong At The Big Gig

Sometimes a show will really kick your butt.

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.

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Do this type of work long enough, and there will come a certain day. On that day, you will think, “If just about half of this audience goes home being totally pissed at me, I’ll call that a win.”

For me, that day came last weekend.

I was handling a show out at the Gallivan Center, a large, outdoor event space in the heart of Salt Lake. The day started well (I didn’t have to fight for parking, and I had both a volunteer crew and my ultra-smart assistant to help me out), and actually ended on a pretty okay note (dancing and cheering), but I would like to have skipped over the middle part.

It all basically boils down to disappointing a large portion of an audience.

I’ve come to terms with the reality that I’m always going to disappoint someone. There will always be “THAT guy” in the crowd who wants the show to have one kind of sound, a sound that you’ve never prioritized (or a sound that you simply don’t want). That person is just going to have to deal – and interestingly, they are often NOT the person writing the checks, so there’s a certain safety in being unruffled by their kerfuffle. However, when a good number of people are in agreement that things just aren’t right, well, that can turn a gig into “40 miles of bad road.”

Disappointment is a case of mismatched expectations. The thing with a show is that a mismatch can happen very early…and then proceed to snowball.

For instance, someone might say to me: “You didn’t seriously expect to do The Gallivan with your mini-concert rig, did you?”

No, I did not expect that, and therein lies a major contributing factor. “Doing The Gallivan” means covering a spread-out crowd of 1500+ people with rock-n-roll volume. I am under no illusions as to my capability in that space (which is no capability at all). What I thought I was going to do was to hit a couple hundred merry-makers with acoustic folk, Bluegrass, and “Newgrass” tunes. I thought they’d be packed pretty closely together near the stage, with maybe the far end of the crowd being up on the second tier of lawn.

I suppose you can guess that’s not what happened.

For most of the night, the area in front of the stage was barely populated at all. I remembered that particular piece of the venue as being turf (back in the day), but now it’s a dancefloor. That meant that the patrons who wanted to sit – and that was the vast majority – basically started where I was at FOH. Effectively, this created a condition like what you would see at a larger festival, where the barricade might be 40 – 50 feet from the stage.

Now add to this that we had a pretty ample crowd, and that they ended about 150 feet away from the deck.

Also add in that a lot of what we were doing was “traditional,” or in other words, acoustic instruments that were miced. Folk and Bluegrass really are not that loud in the final analysis, which means that making them unnaturally loud in order to get “throw” from a single source is a difficult proposition.

Fifty feet out, there were points where I was lucky to make about 85 dB SPL C-weighted. After that, gain-before-feedback started to become a real conundrum. Now, imagine that you’re three times that distance, at where the lawn ends. That meant that all you got was about 75 dB C, which isn’t much to compete against traffic noise and conversations.

Things got louder later. The closing acts were acoustic-electric “Newgrass,” which meant I could make as much noise as the rig would give me. That would have gotten us music lovers to about 94 – 97 dB C at FOH (by my guess). The folks in the back, then, were just starting to hear home-stereo level noise.

In any case, I was complained at quite a bit (by my standards). I think I spent at least 50% of the show wanting to crawl into a hole and hide. That we had some feedback issues didn’t help…when you’re riding the ragged edge trying to make more volume, you sometimes fall off the surfboard. We also had some connectivity problems with the middle act that put us behind, and further aggravated my sense of not delivering a standout performance.

Like I said, there was some good news by the time we shut the power off. Even before then, too. The people who were getting the volume they wanted appeared to be enjoying themselves. Most of the bands seemed happy with how the sound worked out on the stage itself, and the audience as a whole was joyous enough at the end that I no longer felt the oppressive weight of imagining the crowd as a disgruntled gestalt entity. Still, I wasn’t going to win any awards for how everything turned out. I was smarting pretty badly during the strike and van pack.

But, you know, some of the most effective learning in life happens when you fall over and tear up your knees. I can certainly tell you what I think could be done to make the next go-around a bit more comfortable.

That will have to wait for the next installment, though.


How Could 10 Watts Be Too Loud?

We think audiences want volume, but I’m not sure that’s really true.

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.

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I’m not just hammering on players here. The context for this is very much “pro-sound.”

I used to have this regular gig that I loved dearly. Fats Grill is now a hole in the ground, but just a couple of years ago we had live-music every weekend. The PA in the downstairs venue was anything but huge, and yet it was very, very adequate for the space. The mid-highs were mated to an amplifier capable of putting 1000-watt peaks into each box. That works out to a theoretical 127 dB SPL peak for each enclosure – if only at close range (1 meter).

If you were in the middle of the room, you were about 4 meters (or 13-ish feet) away. We’ll say that makes for a practical peak of 115 dB SPL per mid-high, although the room being tightly enclosed would make the real number around 118. Put the two boxes together, and you had a system that could deliver a 121 dB peak in the midrange, plus whatever the subs could do.

Now then.

In pro-audio terms, a 121 dB peak isn’t considered “really loud.” It’s especially not considered loud when you realize that the continuous level, or what humans hear readily, was about 10 dB below that.

But here’s the thing: My experience suggests to me strongly that most folks don’t really want their live-music as loud as “music people” might think. Even for those that love their Rock and/ or Roll, 111 dB continuous can be considered bombardment. This is especially true for the 100 Hz – 15 kHz range. (Subwoofer material is far more easily tolerated, generally speaking.)

At Fats, I very regularly had the system limited so that the top boxes hit a brick wall at their amplifier’s -10 dB point. That’s a peak output of 111 dB in the middle of the audience area, with only about 101 dB of continuous level. That still felt loud for some people. It felt loud for me at times. I wore my earplugs religiously.

To be fair, the PA wasn’t the only thing making noise in the room. The monitor rig and the band’s instrumentation could easily give the total acoustical output a shove that got you into the upper reaches of the 100 dB decade. But even so, you have to realize that 101 dB of continuous system output at room-center resulted from only about 10 watts of continuous input. Remember that I said the limiter for FOH stopped the peaks at 10 dB down. So, that 1000-peak-watt amp was now really only 100 watts maximum, with the continuous power available being 10 dB down from that.

What I’m NOT saying here is that we should all downsize our audio rigs to run on hamster wheels. Headroom (holistic headroom, that is) continues to be a very good idea. There are situations where very large peak-to-continuous ratios have to be handled. What I am saying on balance, though, is that dumping a ton of resources into system capacity that’s actually excess isn’t something I can advise. I just can’t escape this ever-building perception that what a good number of live-music audiences really want are balanced mixes which stay well under an A-weighted level of 100 dB SPL continuous. Add the subwoofer information and you might get to 100 dB or more on another weighting, but that’s a different story.

(And, of course, we have to do what we have to do. Keeping up with a band that’s running hot is a necessity. There were plenty of Fats gigs where I started opening the limiters a little. There was one night where I had to adjust my threshold up to the point where the main amp would show clipping – and then drive hard into that limiting point.)

But there are plenty of gigs that aren’t a slugging match. In those cases, 10 watts of continuous input power might be all that’s actually used. Maybe even less than that. Ten watts can be “too loud” sometimes. I’ve gotten complained at during acoustic shows that people could easily talk over, for goodness sake. I did a few nights at a place with a very nice install that you could barely use in any meaningful way; You would just start pushing some clarity past the monitor wash, and somebody would comment that the music was too loud.

A lot of us aspire to “the big rig,” and I don’t think there’s anything wrong with that on the surface. I simply urge caution. A huge system can be hard to get people to pay for, requires a lot of logistical work, and may be a tremendous amount of excess capacity that never gets leveraged.


Loud, Low, Little

You may pick two, maximum.

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.

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Most of you have probably heard the old chestnut, “Good, fast, cheap. You may pick two of the three.” The saying is an “iron law” of project management.

There’s a very similar law when it comes to loudspeakers:

A loudspeaker might be inherently efficient (Loud), it might reproduce useful low-frequency information (Low), and it might be compact in size (Little). You can’t get more than two of those things to happen at once.

By way of example, let’s take a gander at the high-frequency horn section in your typical, full-range, live-sound box. In all likelihood, it produces quite a bit of SPL with not very much power – lots of affordable, high-frequency compression drivers won’t handle more than 50 watts of continuous input. Heck, some can barely manage 20! The driver is quite small, especially when compared to a 12″ or 15″ cone.

Loud and little is 100% within that driver’s wheelhouse, but it won’t go low. If it did, there wouldn’t be a low-frequency driver in the cabinet. To prevent that itty-bitty compression driver from being wrecked, a high-pass crossover filter is needed. The corner frequency of that filter might be up at 2.5 kHz or so. There’s nobody on Earth who would confuse the high-midrange/ high-frequency transition zone for “lows.”

The above is fairly intuitive for most, but it can be a bit easier to get bamboozled when you see a big driver. An 18″ driver must be able to make really low-frequency material at high volume, right? Well…maybe. The box that driver is sitting in is a HUGE part of the equation; A large-diameter diaphragm isn’t enough. The smaller the box gets, the more power you have to dump into the driver to get the really deep material to play “loud.” Past a certain point, things get ridiculous in one way or another, which includes the unbridled hilarity of cooking the voice coil or destroying the suspension.

A compact subwoofer is highly unlikely to do a whole lot for you below about 50 Hz. Forty Hz might be doable at “half power” if the manufacturer is using a bandpass design for the box. (A bandpass design is great in a small frequency range, and terrible everywhere else – which is perfectly fine for a subwoofer.)

You have to decide on what you actually need, versus what you think you need.

For rock-band reinforcement, really deep bass actually isn’t a top requirement. Mostly, what we need is high output, though not so high that we run the whole audience out of the room. I haven’t really cared about anything below 50 Hz for a long time, especially because large SPL at low frequency is what annoys the “neighbors” the most easily. “Varsity-Level” EDM, on the other hand, can be HIGHLY dependent on very, very low frequency information (35 Hz or even lower) that has to be at levels exceeding 110 dB SPL C, slow-average. Doing that in a reasonable way demands bigger boxes, or several truckloads of smaller boxes.

So, when you’re out shopping for low-frequency loudspeakers, be wary of anything that claims to be effective for concert sound below 50 Hz, while also fitting easily into the trunk of a compact car. If a single box is going to play low AND loud without a staggering amount of amplifier power, it just can’t be little.


Double Hung Discussion

It’s not magic, and it may not be for you. It works for me, though.

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.

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On the heels of my last article, it came to may attention that some folks were – shall we say – perplexed about my whole “double hung” PA deployment. As can be the case, I didn’t really go into any nuance about why I did it, or what I expected to get out of it. This lead some folks to feel that it was a really bizarre way to go about things, especially when a simpler solution might have been a better option.

The observations I became aware of are appropriate and astute, so I think it’s worth talking about them.

Why Do It At All?

First, we can start with that logistics thing again.

When I put my current system together, I had to consider what I was wanting to do. My desire was to have a compact, modular, and flexible rig that could “degrade gracefully” in the event of a problem. I also had no desire to compete with the varsity-level concert systems around town. To do so would have required an enormous investment in both gear and transport, one that I was unwilling (and unable) to make.

What I’ve ended up with, then, is a number of smaller boxes. If I need more raw output, I can arrange them so that they’re all hitting the same general area. I also have the option of deploying for a much wider area, but with reduced total output capability. I wouldn’t have that same set of options with a small number of larger, louder enclosures.

That’s the basic force behind why I have the rig that I have. Next come the more direct and immediate issues.

The first thing is just a practical consideration: Because my transport vehicle isn’t particularly large, I don’t really have the necessary packing options required to “leave gear on the truck.” If I’m getting the rig out, I might as well get all of it out. This leads to a situation where I figure that I might as well find a way to deploy everything all the time. The gear is meant to make noise, not sit around. “Double hung” lets me do that in a way that makes theoretical sense (I’ll say more on why in a bit).

The second reason is less practical. I have a bit of a penchant for the unconventional and off-the-wall. I sometimes enjoy experiments for the sake of doing them, and running a double hung system is just that kind of thing. I like doing it to find out what it’s like to do it.

Running double hung is NOT, by any means, more practical than other deployments. Especially if you’re new to this whole noise-louderization job, going with this setup is NOT some sort of magical band-aid that is going to fix your sound problems. Also, if you’re getting good results with a much simpler way of doing things, going to the extra trouble very well may not be worth it.

At the same time, though, the reality of making this kind of deployment happen is not really all that complicated. You can do it very easily by connecting one pair to the left side of your main mix, and the other pair to the right side. Then, you just pan to one side or the other as you desire.

System Output And Response

Up above, I mentioned that running my system as a double hung made sense in terms of audio theory. Here’s the explanation as to why. It’s a bit involved, but stick with me.

I haven’t actually measured the maximum output of my FOH mid-highs, but Turbosound claims that they’ll each make a 128 dB SPL peak. I’m assuming that’s at 1 meter, and an instantaneous value. As such, my best guess at their maximum continuous performance, run hard into their limiters, would be 118 dB SPL at 1 meter.

If I run them all together as one large rig, most people will probably NOT hear the various boxes sum coherently. So, the incoherent SPL addition formula is what’s necessary: 10 Log10[10^(dB SPL/ 10) + 10^(dB SPL/ 10)…]. What I put into Wolfram Alpha is 10 Log10[10^11.8 + 10^11.8 + 10^11.8 + 10^11.8].

What I get out is a theoretical, total continuous system output of 124 dB SPL at 1 meter, ignoring any contribution from the subwoofers.

At this point, you would be quite right to say that I can supposedly get to that number in one of two ways. The first, simple way, is to just put everything into all four boxes. The second, not simple way is to put some things in some boxes and not in others. Either way, the total summed sound pressure should be basically the same. The math doesn’t care about the per-box content. So, why not just do it simply?

Because there’s more to life than just simply getting to the maximum system output level.

By necessity of there being physical space required for the speakers to occupy, the outer pair of enclosures simply can’t create a signal that arrives at precisely the same moment as the signal from the inner pair, as far as the majority of the audience can perceive. Placed close together, the path-length differential between an inner box and an outer box is about 0.0762 meters, or 3 inches.

That doesn’t seem so bad. The speed of sound is about 343 meters/ second in air, so 0.0762 meters is 0.22 ms of delay. That also doesn’t seem so bad…

…until you realize that 0.22 ms is the 1/2 cycle time of 2272 Hz. With the outer boxes being 1/2 cycle late, 2272 Hz would null (as would other frequencies with the same phase relationship). If everything started as measuring perfectly flat, introducing that timing difference into a rig with multiple boxes producing the same material would result in this transfer function:

combfiltering0.22ms

Of course, everything does NOT start out as being perfectly flat, so that craziness is added onto whatever other craziness is already occurring. For most of the audience, plenty of phase weirdness is going on from any PA deployed as two, spaced “stacks” anyway. To put it succinctly, running everything everywhere results in even more giant holes being dug into the critical-for-intelligibility range than were there before.

Running double hung, where the different pairs of boxes produce different sounds, prevents the above problem from happening.

So, when I said that I was running double hung for “clarity,” I was not doing it to fix an existing clarity problem. I was preventing a clarity problem from manifesting itself.

Running absolutely everything into every mid-high, and then having all those mid-highs combine is a simple way to make a system’s mid-highs louder. It’s also a recipe for all kinds of weird phase interactions. These interactions can be used intelligently (in an honest-to-goodness line-array, for instance), but for most of us, they actually make life more difficult. Louder is not necessarily better.

More On Output – Enough Rig For The Gig?

For some folks reading my previous installment, there was real concern that I hadn’t brought enough PA. They took a gander at the compactness of the rig, and said, “There’s no way that’s going to get big-time sound throughout that entire park.”

The people with that concern are entirely correct.

But “rock and roll level everywhere” was not at all what I was trying to do.

The Raw Numbers

What I’ve found is that many people do NOT actually want everything to be “rock and roll” loud over every square inch of an event area. What a good number of events actually want is a comfortable volume up close, with an ability to get away from the noise for the folks who aren’t 100% interested. With this being the case, investing in a system that can be clearly heard at a distance of one mile really isn’t worthwhile for me. (Like I said, I’m not trying to compete with a varsity-level sound company.)

Instead, what I do is to deploy a rig that’s in close proximity to the folks who do want to listen, while less interested people are at a distance. Because the folks who want more volume are closer to the PA, the PA doesn’t have to have crushing output overall. For me, the 110 dB SPL neighborhood is plenty loud, and I can do that for the folks nearby – by virtue of them being nearby.

Big systems that have to cover large areas often have the opposite situation to deal with: The distance differential between the front row and the back row can actually be smaller, although the front row is farther away from the stacks in an absolute sense. With my rig, the people up close are probably about three meters from the PA. The folks far away (who, again, aren’t really interested) might be 50 meters away. That’s more than a 16-fold difference. At a bigger show, there might be a barricade that’s 10 meters from the PA, with the main audience extending out to 100 meters. That’s a much bigger potential audience, but the difference in path lengths to the PA is only 10-fold.

Assuming that the apparent level of the show drops 6 dB for every doubling of distance, my small show loses about 24 decibels from the front row to the folks milling around at 50 meters. The big show, on the other hand, loses about 20 dB. (But they have to “start” much louder.)

That is, where the rubber hits the road is how much output each rig needs at 1 meter. At the big show, they might want to put 120 dB SPL into the front seats. To do that, the level at 1 meter has to be 140 dB. That takes a big, powerful PA. The folks in the back are getting 100 dB, assuming that delays aren’t coming into the picture.

For me to do a show that’s 110 dB for the front row, my PA has to produce about 119 dB at 1 meter. That’s right about what I would expect my compact setup to be able to do, with a small sliver of headroom. At 50 meters, my show has decayed to a still audible (but not “rock show loud”) 86 dB SPL.

That’s what I can do, and I’ve decided to be happy with it – because the folks I work with are likely to be just as happy with that as I am. People don’t hire me to cover stadiums or have chest-collapsing bass. They hire me because they know I’ll do everything in my power to get a balanced mix at “just enough” volume.

The Specifics Of The Show

Ultimately, the real brass tacks are to be found in what the show actually needed.

The show did not need 110 dB SPL anywhere. It needed a PA that sounded decent at a moderate volume.

The genre was folksy, indie material. A 110 dB level would have been thoroughly inappropriate overkill. At FOH control, the show was about 80 – 90 dB, and that was plenty. There were a few times where I was concerned that I might have been a touch too loud for what was going on. In that sense, I had far more than enough PA for raw output. I could have run a single pair of boxes and been just fine, but I didn’t want to get all the speakers out of the van and not use them. As I said before, I chose “double hung” to use all my boxes, and to use them in the way that would be nicest for people’s ears.


If you’re curious about running a double hung setup, I do encourage you to experiment with it. Curiosity is what keeps this industry moving. At the same time, you shouldn’t expect it to completely knock you off your feet. If you have a good-sounding system that runs everything through one pair of mains, adding another pair just to split out some sources is unlikely to cause a cloud-parting, ligh-ray-beaming experience of religious proportions. Somewhat like aux-fed subwoofers, going double hung is a taste-dependent route to accomplishing reinforcement for a live event. For me, it solves a particular problem that is mostly logistical in nature, and it sounds decent doing it.


Does It Have To Be This Loud?

A love-letter to patrons of live music.

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.

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Dear Live-Music Patron,

Occasionally, you have a question to ask an audio human. That question isn’t often posed to me personally, although, in aggregate, the query is probably made multiple times in every city on every night. The question isn’t always direct, and it can morph into different forms – some of which are statements:

“I can’t hear anything except the drums.”

“The guitar on the right is hurting my ears.”

“It’s hard to talk to my girlfriend/ boyfriend in here.”

“Can you keep everything the same, but turn the mains down?”

“Can you make it so the mic doesn’t make that screech again?”

And so on.

Whenever the conversation goes this way, there’s a singular question lying at the heart of the matter:

“Does it have to be this loud?”

There are a number of things I want to say to you regarding that question, but the most important bit has to come first. It’s the one thing that I want you to realize above everything else.

You’re asking a question that is 100% legitimate.

You may have asked it in one way or another, only to be brushed off. You may have had an exasperated expression pointed your way. You may have been given a brusque “Yes” in response. You may have encountered shrugging, swearing, eye-rolling, sneering, or any number of other responses that were rude, unhelpful, or downright mean.

But that doesn’t mean that your question is wrong or stupid. You’re right to ask it. It’s one of the minor tragedies in this business that production people and music players talk amongst themselves so much, and yet almost never have a real conversation with you. Another minor tragedy is that us folks who run the shows are usually not in a position to have a nuanced discussion with you when it would actually be helpful.

It’s hard to explain why it’s so loud when it’s so loud that you have to ask if “it has to be this loud.”

So, I want to try to answer your question. I can’t speak to every individual circumstance, but I can talk about some general cases.

Sometimes No

I am convinced that, at some time in their career, every audio tech has made a show unnecessarily loud. I’ve certainly done it.

As “music people,” we get excited about sonic experiences as an end in themselves. We’re known for endlessly chasing after tiny improvements in some miniscule slice of the audible spectrum. We can spend hours debating the best way to make the bass (“kick”) drum sound like a device capable of extinguishing all multicellular life on the planet. The sheer number of words dedicated to the construction of “massive” rock and roll guitar noises is stunning. The amount of equipment and trickery that can be dedicated to, say, getting a bass guitar to sound “just so” might boggle your mind.

It’s entirely possible for us to become so enraptured in making a show – or even just a small portion of a show – sound a certain way that we don’t realize how much level we’re shoveling into the equation. We get the drums cookin’, and then we realize that the guitars are a little low, and then the bass comes up to balance that out, and then the vocals are buried, so we crank up the vocals and WHAT? I CAN’T HEAR YOU!

It does happen. Sometimes it’s accidental, and sometimes it’s deliberate. Some techs just don’t feel like a rock show is a rock show until they “feel” a certain amount of sound pressure level.

In these cases, when the audio human’s mix choices are the overwhelming factor in a show being too loud, the PA really should be pulled back. It doesn’t have to be that loud. The problem and the solution are simple creatures.

But Sometimes Yes

The thing with live audio is that the problems and the solutions are often not so simple as what I just got into. It’s very possible, especially in a small room, for the sound craftsperson’s decisions to NOT be the overwhelming factor in determining the volume of a gig. I – and others like me – have spent lots of time in situations where we’ve had to deal with an unfortunate consequence of the laws of physics:

The loudest thing in the room is as quiet as we can possibly be, and quite often, a balanced mix requires something else to be much louder than that thing.

If the instrumentalists (drums, bass, guitars, etc) are blasting away at 110 dB without any help from the sound system, then the vocals will have to be in that same neighborhood in order to compete. It’s a conundrum of either being too loud with a flat-out awful mix, or too loud with a mix that’s basically okay. In a case like that, an audio human just has to get on the gas and wait to go home. Someone’s going to be mad at us, and it might as well not be the folks who are into the music.

There’s another overarching situation, though, and that’s the toughest one to talk about. It’s a difficult subject because it has to do with subjectivity and incompatible expectations. What I’m getting at is when some folks want background music, and the show is not…can not be presented as such.

There ARE bands that specialize in playing “dinner” music. They’re great at performing inoffensive selections that provide a bed for conversation at a comfortable volume. What I hope can be understood is that this is indeed a specialization. It’s a carefully cultivated, specific skill that is not universally pursued by musicians. It’s not universally pursued because it’s not universally applicable.

Throughout human history, a great many musical events, musical instruments, and musical artisans have had a singular purpose: To be noticed, front and center. For thousands of years, humans have used instruments like drums and horns as acoustic “force multipliers” – sonic levers, if you will. We have used them to call to each other over long distances, or send signals in the midst of battle. Fanfares have been sounded at the arrivals of kings. On a parallel track, most musicians that I know do not simply play to be involved in the activity of playing. They play so as to be listened to.

Put all that together, and what you have is a presentation of art that simply is not meant to be talked over. In the cases where it’s meant to coexist with a rambunctious audience, it’s even more meant to not be talked over. From the mindset of the players to the technology in use, the experience is designed specifically to stand out from the background. It can’t be reduced to a low rumble. That isn’t what it is. There’s no reason that it has to be painfully loud, but there are many good reasons why a conversation in close proximity might not be practical.

So.

Does it have to be this loud?

Maybe.


Danny’s Unofficial Sound System Taxonomy

Actual “concert rigs” are capable of being really loud. They’re also really expensive.

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.

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

There’s a question in this business that’s rather like the quandary of what someone means when they say “twice as loud.” It’s the question of how a PA system “classes.”

To a certain degree, the query is unanswerable. What might be a perfectly acceptable rock-band PA for one group might not be adequate for a different band. Even so, if you ask the first group whether or not they play through a “rock-band” system, they will probably say yes. In the end, it all comes down to whether a rig satisfies people’s needs or not. The systems I work on are just fine for what I need them to do (most of the time). If you gave them to Dave Rat, however, they wouldn’t fit the bill.

Even if the question can’t be definitively put to rest, it can still be talked about. In my mind, it’s possible to classify FOH PA systems and monitor rigs by means of acoustical output.

Right away, I do have to acknowledge that acoustical output is a sloppy metric. It doesn’t tell you if a rig sounds nice, or is user-friendly, or if it’s likely to survive through the entire show. Reducing the measure of a system to one number involves a LOT of other assumptions being made, and being made “invisibly.” It’s sort of like the whole problem of simple, passive loudspeakers. The manufacturer suggests a certain, broadband wattage number to use, all while assuming that major “edge cases” will be avoided by the end user.

But one-number metrics sure do make things simple…

Anyway.

My Proposed “Rule Of Quarters”

So, as I present my personal taxonomy of audio rigs, let me also mention some of my other assumptions for a “pro” PA system:

1) I assume that a system can be tuned such that any particular half-octave range of frequencies will have an average level of no more than +/- 6 dB from an arbitrary reference point. Whether the system is actually tuned that way is a whole other matter. (My assumption might also be too lenient. I would certainly prefer for a rig’s third-octave averages to be no more than +/- 3 dB from the reference, to be perfectly frank. I’d also like a $10 million estate where I can hold concerts.)

2) I assume that the system can provide its stated output from 50 Hz to 15000 Hz. Yes, some shows require “very deep” low-frequency reproduction, but it seems that 50 Hz is low enough to cover the majority of shows being done, especially in a small-venue context. On the HF side, it seems to me that very few people can actually hear above 16 kHz, so there’s no point in putting superhuman effort into reproducing the last half-octave of theoretical audio bandwidth. Don’t get me wrong – it’s great if the rig can actually go all the way out to 20 kHz, but it’s not really a critical thing for me.

3) I assume that the system has only a 1:100 chance (or less) of developing a major problem during the show. To me, a major problem is one that is actually a PA equipment failure, is noticeable to over 50% of the audience, and requires the space of more than 5 minutes to get fixed.

If all the above is in the right place, then I personally class PA systems into four basic categories. The categories follow a “rule of quarters,” where each PA class is capable of four times the output of its predecessor. Please note that I merely said “capable.” I’m not saying that a PA system SHOULD be producing the stated output, I’m only saying that it should be ABLE to produce it.

Also, as a note about the math I’m using for these numbers, I do make it a point to use “worst case” models for things. That is, I knock 12 dB off the peak output of a loudspeaker just to start, and I also treat every doubling of distance from a box to result in a 6 dB loss of apparent SPL. I also neglect to account for the use of subwoofers, and assume that full-range boxes are doing all the work. I prefer to underestimate PA performance, because it’s better to have deployed a Full-Concert rig and wish you’d brought a Foreground Music system than to be in the opposite situation.

Spoken Word

Minimum potential SPL at audience center, continuous: 97 dB

This isn’t too tough to achieve, especially in a small space. If the audience center is 25 feet (7.62 meters) from the PA, and they can hear two boxes firing together, then each box has to produce about 112 dB at one meter. A relatively inexpensive loudspeaker (like a Peavey PVx12) with an amp rated for 400 watts continuous power should be able to do that with a little bit of room left over – but not much room, to be brutally honest.

Also, it’s important to note that 97 dB SPL, continuous, is REALLY LOUD for speech. Something like 75 – 85 dB is much more natural.

Background Music

Minimum potential SPL at audience center, continuous: 103 dB

This is rather more demanding. For a 25-foot audience centerpoint being covered by two boxes, each box has to produce about 118 dB continuous at close range. This means that you would already be in the territory of something like a JBL PRX425, powered by an amp rated for 1200 watts continuous output. (It’s a bit sobering to realize that what looks like a pretty beefy rig might only qualify as a “background” system.)

Foreground Music

Minimum potential SPL at audience center, continuous: 109 dB

Doing this at 25 feet with two boxes requires something like a Peavey QW4F…and a lot of amplifier power.

Full Concert

Minimum potential SPL at audience center, continuous: 115 dB

If you want to know why live-sound is so expensive, especially at larger scales, this is an excellent example. With $4800 worth of loudspeakers (not to mention the cost of the amps, cabling, processing, subwoofer setup, and so on), it’s actually possible to, er, actually, NOT QUITE make the necessary output. Even in a small venue.

Also, there’s the whole issue that just building a big pile of PA doesn’t always sound so great. Boxes combining incoherently cause all kinds of coverage hotspots and comb filtering. It’s up to you to figure out what you can tolerate, of course.

And, of course, just because a system can make 115 dB continuous doesn’t mean that you actually have to hit that mark.

Don’t Be Depressed

Honest-to-goodness, varsity-level audio requires a lot of gear. It requires a lot of gear because varsity-level audio means having a ton of output available, even if you don’t use it.

In the small-venue world, the chances of us truly doing varsity-level audio are pretty small, and that’s okay. That doesn’t mean we can’t have a varsity-level attitude about what we’re doing, and that doesn’t mean that our shows have to be disappointing. We just have to realize where we stack up, and take pride in our work regardless.

As an example, at my regular gig, “full-throttle” for an FOH loudspeaker is 117 dB SPL at one meter. “Crowd center” is only about 12 feet from the boxes, so their worst-case output is 106 dB continuous individually, or 109 dB continuous as a pair. According to my own classification methods, the system just barely qualifies as a “foreground music” rig.

But I rarely run it at full tilt.

In fact, I often limit the PA to 10 dB below its full output capability.

“Full Concert” capability is nice, but it’s a difficult bar to reach – and you may not actually need it.


Loud Doesn’t Create Excitement

A guest post for Schwilly Family Musicians.

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.

amped

The folks in the audience have to be “amped up” about your songs before the privilege of volume is granted.

The full article is here.


How Much Output Should I Expect?

A calculator for figuring out how much SPL a reasonably-powered rig can develop.

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.

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

As a follow-on to my article about buying amplifiers, I thought it would be helpful to supply an extra tool. The purpose of this calculator is to give you an idea of the SPL delivered by a “sanely” powered audio rig.

A common mistake made when estimating output is to assume that the continuous power the amp is rated for will be easily applied to a loudspeaker. This leads to inflated estimations of PA performance, because, in reality, actually applying the rated continuous power of the amp is relatively difficult. It’s possible with a signal of narrow bandwidth and narrow dynamic range – like feedback, or sine-wave synth sounds, but most music doesn’t behave that way. Most of the time, the signal peaks are far above the continuous level…

…and, to be brutally honest, continuous output is what really counts.


This Calculator Requires Javascript

This calculator is an “aid” only. You should not rely upon it solely, especially if you are using it to help make decisions that have legal implications or involve large amounts of money. (I’ve checked it for glaring errors, but other bugs may remain.) The calculator assumes that you have the knowledge necessary to connect loudspeakers to amplifiers in such a way that the recommended power is applied.


Enter the sensitivity (SPL @ 1 watt @ 1 meter) of the loudspeakers you wish to use:

Enter the peak power rating of your speakers, if you want slightly higher performance at the expense of some safety. If you prefer greater safety, enter half the peak rating:

Enter the number of loudspeakers you intend to use:

Enter the distance from the loudspeakers to where you will be listening. Indicate whether the measurement is in feet or meters. (Measurements working out to be less than 1 meter will be clamped to 1 meter.)

Click the button to process the above information:

Recommended amplifier continuous power rating at loudspeaker impedance:
0 Watts

Calculated actual continuous power easily deliverable to each loudspeaker:
0 Watts

Calculated maximum continuous output for one loudspeaker at 1 meter:
0 dB SPL

Calculated maximum continuous output for one loudspeaker at the given listening position:
0 dB SPL

Calculated maximum continous output for entire system at the given listening position:
0 dB SPL

How The Calculator Works

First, if you want to examine the calculator’s code, you can get it here: Maxoutput.js

This calculator is intentionally designed to give a “lowball” estimate of your total output.

First, the calculator divides your given amplifier rating in half, operating on the assumption that an amp rated with sine-wave input will have a continuous power of roughly half its peak capability. An amp driven into distortion or limiting will have a higher continuous output capability, although the peak output will remain fixed.

The calculator then assumes that it will only be easy for you to drive the amp to a continuous output of -12 dB referenced to the peak output. Driving the amp into distortion or limiting, or driving the amp with heavily compressed material can cause the achievable continuous output to rise.

The calculator takes the above two assumptions and figures the continuous acoustic output of one loudspeaker with a continuous input of -12 dB referenced to the peak wattage available.

The next step is to figure the apparent level drop due to distance. The calculator uses the “worst case scenario” of inverse square, or 6 dB of SPL lost for every doubling of distance. This essentially presumes that the system is being run in an anechoic environment, where sound pressure waves traveling away from the listener are lost forever. This is rarely true, especially indoors, but it’s better to return a more conservative answer than an “overhyped” number.

The final bit is to sum the SPLs of all the loudspeakers specified to be in the system. This is tricky, because the exact deployment of the rig has a large effect – and the calculator can’t know what you’re going to do. The assumption is that all the loudspeakers are audible to the listener, but that half of them appear to be half as loud.


Loud Thoughts

“Loud” is a subjective sort of business.

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.

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

The concept of “loud” is really amorphous, especially when you consider just how important it is to live shows. A show that’s too loud for a given situation will quickly turn into a mess, in one way or another. Getting a desired signal “loud enough” in a certain monitor mix may be key to a great performance.

And yet…”loud” is subjective. Perceived changes in level are highly personalized. People tolerate quite a bit of level when listening to music they like, and tolerate almost no volume at all when hearing something that they hate. One hundred decibels SPL might be a lot of fun when it’s thumping bass, but it can also be downright abrasive when it’s happening at 2500 Hz.

Twice As Loud

Take a look at that heading. Do you realize that nobody actually, truly knows what “twice as loud” means?

People might think they know. You’ll hear statements like “people generally think 6 dB is about twice as loud,” but then later someone else will say, “people perceive a 10 dB difference to be twice as loud.” There’s a range of perception, and it’s pretty sloppy when you actually do the math involved.

What I mean is this. The decibel is a measure of power. (You can convert other things, like voltage and pressure, into power equivalents.) Twice the power is 3 dB, period. It’s a mathematical definition that the industry has embraced for decades. It’s an objective, quantitative measurement of a ratio. Now, think about the range of perception that I presented just now. It’s a little eyebrow raising when you realize that the range for perceiving “twice as loud” is anywhere from 4X to 10X the power of the original signal. If a 1000 watt PA system at full tilt is the baseline, then there are listeners who would consider the output to be doubled at 4000 watts…and other folks who wouldn’t say it was twice as loud until a 10kW system was tickling its clip lights!

It’s because of this uncertainty that I try (and encourage others to seriously consider) communicating in terms of decibels. Especially in the context of dialing up a PA or monitor rig to everybody’s satisfaction, it helps greatly if some sort of quantitative and objective reference point is used. Yes, statements like “I need the guitar to be twice as loud,” or “I think the mix needs 10% more of the backup singers” ARE quantitative – but they aren’t objective. Do you need 3dB more guitar? Six decibels? Ten? Do you want only 0.4 dB more of the backup singers? (Because that’s what [10 log 1.1] works out to.) Communicating in decibels is far less arbitrary.

(The irony of using a qualitative phrase like “far less” in the context of advocating for objective quantification is not lost on me, by the way.)

The Meter Is Only Partially Valid As An Argument

Even if nobody actually knows what “twice as loud” means, one thing that people do know is when they feel a show is too loud.

For those of use who embrace measurement and objectivity, there’s a tendency that we have. When we hear a subjective statement, we get this urge to fire up a meter and figure out if that statement is true. I’m all for this behavior in many scenarios. Challenging unsubstantiated hoo-ha is, I think, one of the areas of pro-audio that still has some “frontier” left in it. My opinion is that more claims need to be challenged with the question, “Where’s your data?”

But when it comes to the topic of “loud,” especially the problem of “too loud,” whipping out an SPL meter and trying to argue on the basis of objectivity is of only narrow appropriateness. In the case of a show that feels too loud for someone, the meter can help you calibrate their perception of loud to an actual number that you can use. You can then decide if trying to achieve a substantially lower reading is feasible or desirable. If a full-on rock band is playing in a room, making 100 dBC at FOH without the PA even contributing, and one person thinks they only ought to be 85 dB C…that one person is probably out of luck. The laws of physics are really unlikely to let you fulfill that expectation. At the same time, you have to realize that your meter reading (which might suggest that the PA is only contributing three more decibels to the show) is irrelevant to that person’s perception.

If something is too loud for someone, the numbers from your meter have limited value. They can help you form a justifying argument for why the show level is where it is, but they’re not a valid argument all by themselves.