Time and technology have tempered that with me. That, and taking a lot of hearing damage in the process (although I can probably blame years of radio with blaring headphones on for hours on end for most of that).
The lesson that a lot of people miss out on is that there's a difference between "loud" and "repulsive". It's all about striking a balance in not only the mix, but the spectral content of your system. Oh yeah, having an understanding of how the ear works and how the brain processes sounds (psychoacoustics) will put you in a good position to be able to tweak your system.
First, here's a really quick lesson in psychoacoustics and the mechanical functions of ear. There will not be a quiz afterwards, and I'll spare you a lot of the medical jargon:
The Frequency Response Of Our Ears Is Anything But Flat
Evolution has adapted our hearing to be most sensitive between 300 to about 3000 Hz. Coincidentally, that's about the range of human speech. Pretty cool, huh?
We're especially sensitive between 1000 to 3000 Hz, because that's where the cues our in our speech patterns to discern between "P", "B", "T", and so on. So, if you've got a lot of energy in your mix in this region, you're going to sound louder than you really are. In other words, you could be reading a sound pressure level (SPL) of only about 90dB (which is kind of quiet for a rock band), but still driving people out of the room.
I'll almost always cut 2200 to 2800 Hz by a few dB, even if room analysis says I don't need it. What you're essentially doing is counteracting the ear's response curve, and that allows you to bring everything else up.
One of the funniest statements I've heard was from the sound man for Houston-based rockers King's X. He said something along the lines of "those frequencies should have never been invented".
Convey Power With The Low End
Down below about 150 Hz is where some real magic lives. This is where you can really convey a sense of power without hurting people's ears. But, you've got to have the speakers to support it. Trying to coax 60 Hz out of a 10" speaker is just going to guarantee you that you'll have to recone that sucker sooner than later.
On my big systems, I'll usually run RTA (Real Time Analysis) on the room and get everything fairly flat (with the highs falling off starting at about 8 kHz). Then I'll crank the send to the subs up about 6dB. For most rooms, that seems to be the recipe.
Be Careful In Power Alley
"Power Alley" is what a lot of sound guys affectionately call 200 to 500 Hz. That's where you can deliver a lot of punch in a mix. It's also where you can turn a mix to mud very quickly. Why? If you stop and think about it, every instrument (including the voice) has fundamental frequencies in that band.
See how you can quickly get a build up in that space? On top of that, guess what the average 30' x 15' x 8' room starts resonating at? About 250 Hz depending on who's calculation you're using.
The room resonance will usually show up on RTA, but you have to be aware that it's easy to wind up in a null of the wave...and then the analyzer is going to tell you to add in even more energy. Even if you don't have an RTA, make yourself a CD or MP3 of pink noise and play it back through your system. Then, just walking around the room you can hear where the nulls and peaks are in the response. Unless you're using a multi-zone PA system, the best you can do is compromise here. Just remember if your mix feels like it's starting to get away from you, this is where I usually make a cut to try to clear things up.
Keep this in mind when you're setting up your mix...if you find yourself cutting the same frequency on every channel then you've got a system issue. Fix it with your main EQ and then go back to your individual channels.
The Case For Compression
It used to be that compressors were really luxury items. On my big systems back in the 80's I think I might have had just a couple of channels worth across the mains (it was a Symetrix that set me back several hundred dollars). Flash forward to the late 90's, and you can get 8 channels worth of better compression (along with gating and expansion) for less money (the Presonus ACP-88 is still a favorite). Now, it's pretty easy to find consoles with compression built into at least the sub-groups if not every channel. The Presonus StudioLive console I just deployed has the digital equivalent of 30 some-odd compressors and limiters in it...just amazing.
Adding just a bit of compression (say 1.5:1 or 2:1) across your mains will tighten everything up and add density to the mix. Again, giving the impression of power without actually pummeling your audience. Plus, it makes you sound more "like the record" for those of you interested in such things.
On a very simple level, compression reduces the dynamic range of music (the difference between the softest and loudest sounds). It literally lets you cram more sound into a smaller space. Radio stations have been using it for decades, and then about 10 years ago (when MP3's really started to proliferate) mastering engineers starting using it on recordings. There were repercussions, and we'll delve into that later.
Make The Volume Fit The Room
Just my opinion, but there's some music that demands to be loud (most rock-n-roll), and then there's music that shouldn't be. I remember going to see Willie Nelson back in the late 70's. I wound up leaving after 4 songs....he was louder than Black Sabbath (who I had see a couple of weeks before). That, and the system wasn't tuned very well. Didn't matter...I found out later that's the way Willie wanted it. Sorry, but "Blue Eyes Crying In The Rain" at 112 dB was just silly.
What ever your music and wherever you're playing, watch the audience. If they're retreating, then you probably need to address something.
Don't get me wrong, I'm not against bumping the master up a bit as the night goes on and people's inhibitions get lowered. Just don't go past what the room / music dictate. And definitely don't go beyond what you're system can deliver cleanly.
It Sounded Better At Sound Check Earlier...
As you up the volume, funny things start happening to your hearing. Your middle ear actually has a limiter function engineered into it. And remember how I said your hearing was anything but a flat frequency response? Well, as things get louder that response curve tends to flatten out. That was discovered by a couple of dudes named Fletcher and Munson all the way back in 1933.
I won't repeat their research, but check out the idea behind the Fletcher-Munson curves on Wiki-pedia. This is the reason you need to EQ your system at the level you intend to play out. If you EQ it loud and then turn it down, the lows and highs will be weak. Do the opposite and EQ at a reduced volume (because the bar staff doesn't want you to run their regular afternoon drunks off), when you turn it up it's going to be overly boomy and strident.
Have you ever wondered what that button on your stereo marked "Loudness" or "Loud" was doing? Well, that's it...it's correcting for the change in our hearing when the the volume is turned down. You can scratch "Find out what that freakin' button does" off your bucket list now.
I realize it got a little heady in this article, and I appreciate the folks that made it through!
I've mentioned some things about compression this week, and that's probably one of the most misunderstood aspects of audio processing. Next week, we'll talk about using compression in a live setting. We'll also talk about compression's cousin, limiting.
Until then, keep the meters out of the red.
Ken
Ken Carver has been a musician and performer since the early 70's, and involved with live music production since the mid 70's. He worked for 15 years as a broadcast engineer, building numerous studios and transmitter sites around Texas. He's also worked in Critical Care Communications for the medical industry, R&D for an automated lighting manufacturer, and owned Project Lighting & Sound in the 80's. He currently heads up an R&D Hardware Technician Team at National Instruments in Austin, and still performs on the weekends in the Central Texas area. You can reach Ken at itsjustlogistics@gmail.com
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