Sunday, March 22, 2009

standingWaves

Sitting here in the surprisingly nice Richmond VA airport, so I thought I'd check in. Cool cabby on the ride here. He saw my big PHP book and started asking me about what I was doing, so that pretty much filled up the 20 minute cab ride.

Last night's show was kinda just alright for me, personally. It's funny because Phil and Stacy both thought it was the best show of the weekend. It's just goes to show, you never know. I've learned through the years (you never let me down..) that I have absolutely the most subjective opinion about the quality of any given show of anyone in the listening world. It's the double edge sword that keeps us from putting out more LiveDownloads. Typically for me, the quality of the experience that I have on any given night is directly proportional to the frequency distribution between 40 and 150 Hz in the location on the stage at which I'm standing. That's a pretty specific requirement, but last night it just wasn't that happening. The theater we were playing in last night was Very Big. Very Big means a lot of air that you have to get moving before the entire room starts to feel right, which is what makes it sound good between 40-150 Hz wherever I am on stage.

I suppose that we probably wouldn't be as subject to the peculiarities of a given rooms acoustics if we were a more electric band. Let's just take my bass for example. My bass is a giant wood box that's designed to resonate. I stand next to a drum set. If you were to solo up the signal from my DI during a show and listen to what is making my bass resonate, you'd hear the notes I'm playing, but also the kick drum loud and clear. You hear a good bit of fiddle, or God forbid the electric guitar, and the rest of the stage, muffled. This makes my bass essentially the biggest microphone on the stage, with a frequency response that tapers off at about 100 Hz.

What this means to me is that if the room is shaped just so, and you never know until you start playing, there's the possibility of a 'standing wave' on certain notes. A standing wave is one that has a wavelength that's some multiple of the dimensions of the stage we're playing. Suppose I play an open D. Suppose that D vibrates at a frequency of 65 Hz. That means that 65 times every second that string is going to return to more or less the same place in space on my bass (nice). While that string is vibrating it's sending a signal to my amp and to Mikey out in front. That string is going to cause air to be pushed out of the speakers 65 times a second. The air being pushed out of those speakers is going to travel at the speed of sound and bounce off of hard surfaces and dancing bodies alike. The hard surfaces reflect the sound much better, and those soundwaves bounce off and travel back toward me. Meanwhile, other soundwaves have been continuing to come out of my amp and the PA. If the note that I'm playing at the time lines up in a certain reinforcing way with the note that's bouncing back toward me from the wall and the PA, you get a standing wave. That's when feedback begins, and my night starts to go downhill.

Other nights it's the exact opposite, and the note that's bouncing off the wall is totally out of sync with the note that I'm playing at the time. That's when you get 'phase cancellation', which means that the soundwaves are canceling each other out. That's even worse than a standing wave for me, because then there's really no balls to the sound. Phase cancellation is what makes outdoor concerts sound weird when the wind is blowing and you're about 100 yards away from the stage and the sound kinda shifts around and sounds, well, phasey..

And then some nights, the PA and the amp and my bass are all playing nice with each other and you get that nice even low end. A nice even low end means ceasing to consider the sound and actually listening to what my bandmates are playing. That's a good night.

And then some nights, the PA and the amp and my bass are all playing nice with each other, but we still can't get it sounding right. That was last night. It usually happens in a Big Room because the Big Room swallows sound waves and doesn't let them come back to you in time to be useful. It sends them back to you much later so that it sounds like a delay on your entire band being blasted back at you.

And then some nights the sound is so God awful that you just say fuck it, and those are usually really great nights. Blacksburg was one of those. It was in a tiny little basement of a club, my bass was acting up all night, but the crowd was blazing. You can't possibly have a bad time in that situation.

Now boarding. Later...

5 comments:

  1. John, unlike you who lives this stuff, I have been going to shows for many years, and never a any clue as to what makes a show sound good, and others, not so. You articulated this subject very well, and I now feel enlightened about it. It's all very interesting, and I appreciate the effort you took to put it out there.

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  2. Interesting stuff, John...thanks for the insights! What would you consider some of the best venues you've played at with regards to your sound?

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  3. Ahhhhhhhhh the 'ol standing wave, THAT is the story of my life ;-)

    I will say that from my taper's experience that your giant wood box is one of the most difficult instruments to capture to my specific tastes in an "electric" setting. I won't even comment on venue acoustics, mic config, location, my frame of mind, etc, BUT when I do grab that wood box just right, all I can say is nicey, nice ...

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  4. Fillmore, HOB Chicago, come immediately to mind as good sounding venues.

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  5. i enjoyed reading that. thanks!

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