Wednesday, March 4, 2015

What I Have Learned about Live Sound

My first live sound “gig” was as a stage hand in Dodge City, Kansas for the Ventures when they played Dodge’s Civic Auditorium (Remember the days when auditoriums were named after their purpose, not some corporate asshole who bought off the city council?) in 1962. I was 14 and had been playing guitar for a couple of years. The Ventures were my heroes. Bob Bogle, Nokie Edwards, Mel Taylor, and Don Wilson were everything I aspired to be as a rock and roll guitarist (The Band that Launched a Thousand Bands). Their song, Slaughter on 10th Avenue, was my favorite of the time. I had bigger aspirations, at the time, for my trumpet playing, but that wild hope was doomed to disappointment.

1) I conned my way into the good graces of the Catholic High School’s head nun (or whatever she was called) and got myself a job lugging the Ventures’ amplifiers into the auditorium and setting up their one microphone for the house sound system. The first thing I learned about live sound came on that gig: age/senility usually comes before talent or knowledge. Dodge City’s auditorium employed an old guy who doesn’t care never gets replaced. Dozens of times, since then, I’ve run into the established house soundgoof ruling shows like a plague on music. Jump to #9 to see why there is damn little hope of fixing any of these problems.

2) When it comes to sound system design and components, weight and convenience are more important than sound quality. Thirty years ago, Carver came out with a line of bullshit and the PM-1.5 amplifier and the phony specs revolution began in earnest in pro amplification.  This POS claimed to produce 450W/8Ω stereo and 1200/8Ω mono with the more important characteristic being a 21 pound total weight when real amplifiers doing that kind of work were a lot closer to 100 pounds. Sound companies and audiofools went nuts over the PM-1.5 and it’s variations. It turned out that the 1.5 was interesting, but fell way short of the claims. The 4Ω minimum operating impedance should have been a tipoff. The Carver amp not only didn’t do what the company claimed it would do, it also sounded awful; especially when it clipped. It clipped often, in fact. When it did, it made this whacked out “splat” sound that often blew up speakers.

None of that stopped sound companies from filling up their racks with Carver 1.5’s and creating awful noises they passed off as “sound reinforcement.” After a while, it became apparent, even to the deaf dudes who mix live music, that the Carvers were pretty damn awful. However, the “light is right” mantra arrived and sound companies have been worshiping that magical concept ever since. The disease has spread to speaker systems. The “miracle of speaker arrays” has invested almost every sound system on the planet and music suffers because of it.

3) Deafness rules the occupation. Back in the 80’s, an audiologist setup a test booth at an AES convention. The audiologists’ tests found that live sound “engineers,” in particular, were consistently functionally deaf. As long as the people running sound systems are incapable of hearing the difference between music and distortion, live music is hopeless.

4) Nobody remembers anything. Back before we had all of this sophisticated equipment, we did “sound reinforcement.” The sad fact is that we did better before we had infinite equipment. Music sounded more like music without tens of thousands of watts and piles of array speakers. I’m unconvinced that technology is taking us anywhere but in the direction pointed out in #9.

5) Sound guys are notoriously ignorant of room acoustics. For example, the practice of making grunting noises so that the sound doofus can attempt to EQ out the room resonances is depressingly ignorant. There is nothing about the information you can get from snorting into a room that will be corrected in system setup. See #6. Sound system speaker placement is traditionally wrong and has been for decades. Of course, the most important thing in a show is the appearance, not the sound, so justifying putting the speakers on the extreme sides of the stage is all about maintaining a visual line-of-sight of the artists from all seats. That doesn’t have any effect on putting the speakers overhead (and low, for close seats), but it would require an ability to think about how sound is propagated in a room.

The simple fact is, the only way to resolve room resonances is with acoustic treatment. You can cut the resonant frequencies from the system, but any transient information (drums, for example) will stimulate the room regardless of the sound system. You could, however, move the speakers, especially the subs, so that they do not optimally stimulate the room. Better yet, don’t overdrive the room unnecessarily so room resonances are working overtime.

6) Sound guys do not understand speaker or microphone polar patterns or even what those characteristics imply. Currently, there is a45-deg-speaker-with-4m-spacing-and-4-5-deg-splay delusional faith in the “miracle” of loudspeaker arrays, regardless of the well-known limitations (by engineers and physicists) of that system design. A quick look at monitor and FOH speaker placement is a pretty strong argument for proof of that ignorance. Even more, the strange practices FOH guys have regarding the fact that their array systems sound so radically different in fairly similar seating positions.

microphones_supercardioidThe total disregard for hyper and super-cardioid off-axis characteristics creates a terror of these very useful microphones because sound guys do not get where the monitors must be positioned. If you look at the polar pattern at left, is it not clear that the response behind the microphone is damn close to the response in front? 90-120  and 240-270 degrees off-axis is pretty amazing, but the traditional monitor placement is idiotic.

frequency-response_sm587) Repeatedly, sound guys select incompatible-to-the-sound-source microphones (SM58 on all vocals) and try to “fix” that with EQ. There are some applications, I suppose, where the SM58 works pretty well. However, GIGO, especially at the beginning of the signal chain is ultimately true. The 58 has mediocre proximity characteristics (so bad, in fact, Shure does not publish that data). The creepy 5dB bump at 2-6kHz emphasizes sibilance problems so irritatingly that characters like Garrison Keillor sound like a rattlesnake with a lisp using that microphone. The “fix” for those problems usually involves a collection of EQ moves that make all of those problems even worse. The real solution would be to dump this mediocre tool and pick a more suitable microphone.

8) In the worst acoustic environments, sound guys almost always over-mic complicated sound sources. In a situation where reflective surfaces are already creating a disaster zone of phase problems, the attitude is consistently “If one mic will do the job, won’t eight be better?” There are few situations where a collection of microphones will make a phase disaster less of a disaster. Complicate that with the fact that more microphones means more bleed from other instruments (and more phase problems on other instruments in the mix) which is usually “fixed” with crap-loads of gating which only fixes the problems when the gates are closed creating an awful sounding drum kit.

The next goofy move from the live crowd is multiple microphones on guitar cabinets, including distance mics. If we’re talking about stacks of amps, mic’ing the damn things is a waste of time. If we’re talking about a combo amp, the sound quality will not be improved with more mics, since there are pretty extreme limits on quality on a live stage. Isolation or tone, those are the options. Pick one and don’t do anything to delude yourself you can have both.

9) The reason all of these problems are unlikely to be solved is that customers are not that critical: beer over music. 30-some years ago, my partner built a spectacular front-loaded, horn-less FOH system and started doing shows with it all over Lincoln and Omaha, Nebraska. The experiment went poorly. The bands he worked with loved the system, but clubs didn’t. It took a few shows until one of the bartenders asked Dan to crank up the system, dramatically. When Dan explained that the system was operating optimally and much more volume would distort the system, the bartender said something along the lines of, “Music lovers don’t drink, drunks like it loud and distorted. Crank it up.”

Unfortunately, that rule is true in almost all music venues. Drunks spend more than people who are there for the music. The louder it is, the more the drunks drink and the more room there is for more drunks, since the music fans will be driven out.

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Wirebender Audio Rants

Over the dozen years I taught audio engineering at Musictech College and McNally Smith College of Music, I accumulated a lot of material that might be useful to all sorts of budding audio techs and musicians. This site will include comments and questions about professional audio standards, practices, and equipment. I will add occasional product reviews with as many objective and irrational opinions as possible.