Comment by xouse | Hacker News Reader

Comment by xouse | Hacker News Reader

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I've always been surprised some inspired performance artist hasn't done this to the live sound feed at a big music festival like Bonnaroo or Coachella yet. Audio runs from the stage/band to a sound guy in the middle of the field who controls the mix then from there it goes back across the field to the PA system mounted on stage. The audio cables are literally just big snakes that run right through the crowd where anyone could access them. Highjack a post mixer cable and bob's your uncle.

The only hitch would be that afaik at festivals the pa arrays are passive so you'd need to steal power too so you can power an amplifier and send a powered signal, but if you managed that it'd be even worse than the tv broadcast intrusion because there's no easy way to shut it off, the sound guy has no control because you're after him in the signal chain and nobody onstage is set up to handle something like that. It's not like beyonce is gonna climb the scaffolding and start unplugging speakers when the crab rave starts playing inexplicably.

Two problems with that approach at large scale shows:

1) These days the cabling is run inside a run of barricade bisecting the crowd, so it's in a secure area the entire time

2) Modern PA systems at shows of that size have almost exclusively moved to digital snakes / audio networks, not analog

To realistically pull that off you'd need production access to the event to tap into the audio network and re-route things. That said, given the number of people with appropriate access and the fact that InfoSec isn't a high priority, that actually seems pretty doable.

Once they realized what was going on though, a few breakers flipped would drop power to the amps or speakers (depending on whether using powered or passive arrays) and it would be over (which would happen pretty quickly since the power distro is very well organized and labeled since quick troubleshooting is often necessary).

I'm actually surprised this doesn't happen with wireless microphones more often. While the industry is slowly moving towards digital transmitters, many broadway shows still use old body pack analog transmitters on their actors. Since these shows are stationary they are likely using the same frequencies for each transmitter every night.

I can't imagine it would be too hard to figure out some of these frequencies and transmit over them into the PA. There is a pilot tone but I don't think it'd be difficult to spoof.

I used to work in a shop that rented out audio equipment to broadway shows.

Not quite the same thing, but James Randi famously debunked a “faith healer” by listening into to their analogue earpiece: https://www.youtube.com/watch?v=q7BQKu0YP8Y

Maybe more on-topic, an early demonstration of long-distance radio was hijacked: https://www.youtube.com/watch?v=sP2qqMegNKA

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