Monday, October 1, 2012

Live Sound 101 and 102

Took an all day class on live sound at the Frequency. It was really well done. It was taught by Dustin and Jourdan Hines (who is worth checking out for touch up private lessons in future). Only complaint is that it was too short.

Where to begin? They told us to buy this book: Modern Recording Techniques, by David Miles Huber and Robert E. Runstein and I will plan to do so.  I was also referred here: http://www.bcae1.com/spkrmlti.htm

101 went through signal chain.

102 went mostly through micing instruments.

There was a lot of information and if I wasn't already knee deep in it I might have felt lost. But I felt about right on. I think I talked too much and asked too many questions...but you snooze you lose. So suck it classmates.

The next day I went out to the storage space and tested all of the GRC pas. I feel like I understand the basics of what is going on with them. I'm still not super clear on sending out fx loops...but this won't be an issue really for GRC or even in running sound for a band at a club usually. It is a bigger deal at a venue. There's lot of stuff in the signal chain that I don't really understand...effects, compressors, gates/limiters...etc. But I get that stuff goes out and comes back and where you place it in the chain matters.

I also learned that high, mid, low eq starts from 0 at 12 o'clock...to the left removes...to the right adds. That's important. Never knew that before.


Most of what I'd already figured out about the GRC pas...matching speakers to amps...hooking up speakers...was confirmed though it was sort of outside the class topics.

By the way...
1. Best...amp watts matches speaker watts
2. Ok but not great...amp watts higher than speaker watts (but hopefully not too much higher or you may blow speaker)
3. Bad...amp watts lower than speaker watts (amp can overheat and melt down, literally).

And in all cases gotta match the ohms from amp to speaker (amp usually says how). Daisy-chaining speakers puts them in parallel...which halves the ohms (8 ohm + 8 ohm in a daisy chain puts out 4 ohm). I still haven't really figured out how one puts speakers in series...I think you might have to hard wire them. But in series the ohms add (8 ohm + 8 ohm = 16 ohm). If you do a combo (some parallel and some series)...get out your calculator.

Other things I learned in class:
  • kissing the mic is good. too far away and you lose something and it is harder to adjust sound
  • place mic in center and close to guitar amp. If two speakers in amp cabinet, only mic one to avoid canceling out phases
  • place bass drum mic in center and just barely inside drum. Off to side is ok...but center likely better.
  • Ok to plug keyboard straight into PA, but you'll get a cleaner and stronger signal using a DI box.
  • Mic signal is very low...mixer gain brings it up to "line level". Dynamic mics have low signal, but condessor are even lower...that's why they need phantom power to boost. Turn off phantom power when up plugging to avoid "pop"
  • Feedback is from pointing mic at speaker. Whether you are pointing mic at speaker depends on the pickup pattern of the mic. Cardiod mostly picks up in front and blocks in back. Omni picks up all around. There are variations on these patterns too...so think about where your monitor speakers point related to pattern of the mic.  So this is why you stand behind main speakers but ok to stand with monitor speakers facing you. With a cardiod mic the pickup is pointed at your head...so that's away from mains and also away from monitors. If you pointed mic at floor it would probably feed back through the monitors...same if you stand in front of mains.
  • There's really no reason to bring a bass amp to a quality venue like Freq or HNS. I should consider not doing it.
  • Live sound is alot about isolating each mic as much as possible.
More as I remember it.


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