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The email blast from the head of my son and daughter's theater group relayed a frantic plea: "We need to raise $16,000 before the upcoming spring performances," Anya Wallach, the executive director of Random Farms Kids' Theater, in Westchester, New York, wrote in late May. If the money didn't materialize in time, she warned, there could be a serious problem with the shows: nobody would hear the actors.
Random Farms, and tens of thousands of other theater companies, schools, churches, broadcasters, and myriad other interests across the country, need to buy new wireless microphones. The majority of professional wireless audio gear in America is about to become obsolete, and illegal to operate. The story of how we got to this strange point involves politics, business, science, and, of course, money.
Story: https://www.wired.com/story/wireless-mics-radio-frequencies-fcc-saga/
(Score: 0) by Anonymous Coward on Monday August 13 2018, @01:27PM (3 children)
And, somewhat after the age of actors that could project their voices to a large theater, there was *wired* sound reinforcement that used a few microphones arranged in front of the stage. Not as clear as individual wireless mics, but with feedback notching for the room, a reasonable job was possible. I did it in high school in the early 1970s, should be much easier now with low cost filtering and processing.
(Score: 2) by RS3 on Monday August 13 2018, @02:36PM (2 children)
Yes, in fact you can buy, and I have a Feedback Eliminator that does DSP and notches out frequencies that it determines are feedbacks. It's cool to watch it work and grab stuff before I can hear it. Sometimes they're false positives, but the notches are pretty narrow, so not much damage to sound quality, but you might waste a notch filter.
Most rooms I've worked in, esp. school auditoriums, have absolutely horrific sound systems- terrible speakers placed badly, so it's an uphill fight from the start. Lots of system tuning / manual EQ notching (which I hate doing but I'm a tuning freak).
Pressure-zone / boundary microphones are pretty cool: PZM, PCC, etc. You place some on the front of the stage, use them carefully, but they can be amazing. You pick up some foot sounds, but it's not as bad as you'd expect. They're amazing for outdoor work where if you can place the speakers yourself (hang or on stands) you can get stunning results. I use them indoors too. Chop off most of the lower frequencies- you only need the clarity, and you'll get very little feedback above 2K or so with the PCCs, for example, unless the main speakers are stupidly behind the front edge of the stage, or are wide-dispersion (not line-array) and are aimed down too much and "hit" the stage.
(Score: 1, Interesting) by Anonymous Coward on Monday August 13 2018, @10:10PM (1 child)
Interesting, I imagined there might be something like the Feedback Eliminator you mention, but never looked. Back in the 70s, we felt we were special with a borrowed third-octave graphic equalizer, and a parametric equalizer that we could use to make a couple of notches (all analog). Luckily, our speakers in the high school auditorium were off to the side of the stage and slightly closer to the audience than the actors & mics, so we did OK.
I've often wondered how much delay is added by all this digital filtering (all the notch filters for example). The delay doesn't have to be very long before something starts to sound "off" -- maybe 0.1 second or even less? (just guessing).
(Score: 3, Informative) by RS3 on Tuesday August 14 2018, @12:07AM
I have one of these: https://www.ebay.com/itm/SABINE-ADAPTIVE-AUDIO-FBX-SOLO-SM820-FEEDBACK-ELIMINATOR-XLR-PHANTOM-MIC-FILTER/273384191478 [ebay.com] Haven't used it in a few years (that's a good thing). They and others make bigger better ones.
Yes, I have, and have recently used 1/3 octave (31-band) and parametric EQ.
Most digital mixers have very fast internal digital sample / processing rate. You can sample at 48KHz, then "upsample" to whatever your DSP / processing can handle, then downsample and D/A, so latency is truly minimal- microseconds. I frequently use a SoundCraft Vi3000 and I think the overall latency is specified at 2mS or so. I forget where you start to hear, and it depends on what you're doing, maybe 15 mS? It has 4 fully parametric EQs per channel and 4 on each output / bus, plus full graphic on outputs and mix busses, but I forget- I think it's more than 31 bands, and you can set the "Q" on those.
Interestingly there's a philosophy I only recently (a few years ago) learned that it's desirable to use some overall delay in an audio system- that it reduces feedback. I've messed with it and it certainly greatly lowers the frequency of feedback. Like 12 mS will pretty much stop anything above 2K or so, depending on all factors such as room, speaker placement, type, mics, etc.
And we use delay to get the "kick" drum's acoustic wave to line up with the subwoofers. Roughly 1 mS per foot of distance. So much fun to be had...