Mic goes down?

[Les]

I recently saw a touring production of The Wizard of Oz at the Bass Performance Hall in Ft. Worth, where they had a sound meltdown. About half of their wireless mics were having severe issues including interference and deafening static feedback noises. The thing that got me was that I could tell when the board op finally muted the mic, but then you'd hear them sneaking the level back in, as if it had magically fixed itself. Not long after that --- PSSSSHT! PSHHHFT!

Funny thing was that I, as a paying audience member ($35 per ticket for 3rd balcony nosebleed seats!) would have preferred the offending mics be muted for the rest of the show! The Bass Hall's acoustics are good enough that I could actually hear them when the mic was off. Not so much when it was feeding back. That sound guy kept sneaking those mics back in all night. And they kept feeding back. All night.

Just got an email from the company today offering to credit our tickets to an upcoming show. I didn't complain or anything (I wouldn't -- I know how live theatre is!), so I assume everyone got these offers.

 

[FACTplayers]

I recently saw a touring production of The Wizard of Oz at the Bass Performance Hall in Ft. Worth, where they had a sound meltdown. About half of their wireless mics were having severe issues including interference and deafening static feedback noises. The thing that got me was that I could tell when the board op finally muted the mic, but then you'd hear them sneaking the level back in, as if it had magically fixed itself. Not long after that --- PSSSSHT! PSHHHFT!

Funny thing was that I, as a paying audience member ($35 per ticket for 3rd balcony nosebleed seats!) would have preferred the offending mics be muted for the rest of the show! The Bass Hall's acoustics are good enough that I could actually hear them when the mic was off. Not so much when it was feeding back. That sound guy kept sneaking those mics back in all night. And they kept feeding back. All night.

Just got an email from the company today offering to credit our tickets to an upcoming show. I didn't complain or anything (I wouldn't -- I know how live theatre is!), so I assume everyone got these offers.

I wonder if the OP was listening to the individual levels of the receivers and not the output on the board. I would have my monitor headphones changing from one output to the next before I tried the house speakers again... This almost makes me wonder if his board wasn't going bad. One of the sound boards I use has 2 channels that intermittently work. When they don't work I get a static sound. I haven't been able to find a repair guy who knows why I am getting the static. I was actually told that the reason the channels keep dying are because the board isn't used daily. I proceeded to ask why our 20 year old spare is in perfect working condition and that gets used (maybe) once a year. He didn't like that question.

 

[waynehoskins]

This was definitely an RF problem, and at a major metro venue on a national tour at that. The venue was quick to point out in interviews that it was the tour's problem, not the venue's.

Presuming it wasn't RF hardware failure, which of course we can't entirely rule out from the outside, it sounds like lack of coordination. How could a tour come through Dallas and not work out the coordination?

Learning point for students: coordinate your RF. Your life will be so much easier after you do. In small towns you can often get away without it, but in big cities there are no vacant TV channels, not one, so you have to do your homework.

 

[FACTplayers]

This was definitely an RF problem, and at a major metro venue on a national tour at that. The venue was quick to point out in interviews that it was the tour's problem, not the venue's.

Presuming it wasn't RF hardware failure, which of course we can't entirely rule out from the outside, it sounds like lack of coordination. How could a tour come through Dallas and not work out the coordination?

Learning point for students: coordinate your RF. Your life will be so much easier after you do. In small towns you can often get away without it, but in big cities there are no vacant TV channels, not one, so you have to do your homework.

I don't doubt you, but it's so hard to believe they would over look something so important as RF coordination. This is a huge learning experience, not only for students, but even those OPs who think they have it all figured out.

 

[Tex]

I don't doubt you, but it's so hard to believe they would over look something so important as RF coordination. This is a huge learning experience, not only for students, but even those OPs who think they have it all figured out.

Our district fine arts programs did a show at this venue last May. 24 wireless mics and no feedback or interference in a three hour show. The tour didn't coordinate the mics. Maybe they thought that in lil' ol' Fort Worth they would be the only RF in town. You'd be surprised how many people think this is a small town and not part of one of the largest metropolitan areas in the country.

 

[DrPinto]

This is my most spectacular sound meltdown:

I was running lights and sound for a show in a high school auditorium. The amps were behind stage, the mixers were at the rear of the house. We ran 2 mixers. My mixer connected to the house amps and all the stage mics via a snake. The other mixer was connected to mine via a 10 foot 1/4" snake. I sent all my inputs to the other mixer using split outs. The 2nd mixer was being used by the video people (they needed a different mix to go to tape). Before I plugged anything in, I checked each outlet with a circuit tester. Everything tested OK. I had a UPS on my board and my computer. What could possible go wrong? (Famous last words).

We were about 10 minutes into the dress rehearsal when suddenly a horribly loud BUZZ came over the house speakers. I immediately brought my master fader down, but it didn't make any difference. I had no idea at all what was happening.

This buzz lasted all of about 5 LONG seconds, then it just stopped. I immediately noticed 2 things. My ups was beeping, indicating the power died, and there was smoke pouring out of the rear of the video crews mixer. A LOT of smoke.

Due to the lack of space where we were working, I was unable to roll up into a ball and cry, so I decided I might as well try to figure out what just happened.

One of the students who was helping out with the production then told me that sometimes when someone steps on the metal plate that runs across the carpet to the outlets at the rear of the house, the circuit breaker trips. This has been going on like this for years! He tells me this now???

The best I can tell, someone stepped on the wire-way, the hot wire made contact with the ground, and 120 volts flowed through the ground wire going to the video sound mixer, melting the mixer's power cable, thus causing the smoke. From there the power came to my mixer via the 1/4" snake. From there it blew out the sound card in my computer, continued down the house snake, and took out one of the inputs into the house amp I was using.

I tried to learn from this experience, but I can't figure out what I could have done differently to have avoided this meltdown and the damage to my computer and the house sound system. Any ideas?

 

[Lambda]

I tried to learn from this experience, but I can't figure out what I could have done differently to have avoided this meltdown and the damage to my computer and the house sound system. Any ideas?

Yikes, what a story. A GFCI outlet or power strip would have prevented the whole fiasco. It would have tripped the instant that any current started to flow to ground.
But you have deeper problems, it seems. You guys ought to start by figuring out why the circuit shorts when somebody steps on that wire way.

 

[DrPinto]

Yikes, what a story. A GFCI outlet or power strip would have prevented the whole fiasco. It would have tripped the instant that any current started to flow to ground.
But you have deeper problems, it seems. You guys ought to start by figuring out why the circuit shorts when somebody steps on that wire way.

I'm not sure if a GFCI strip would have made any difference. When a GFCI trips, it would break the hot (black) wire, not the ground wire. There would still be 120 volts flowing into the mixer via the ground wire in the mixer's power cable. Am I wrong?

 

[Lambda]

I'm not sure if a GFCI strip would have made any difference. When a GFCI trips, it would break the hot (black) wire, not the ground wire. There would still be 120 volts flowing into the mixer via the ground wire in the mixer's power cable. Am I wrong?

It was my understanding that the hot shorted to the ground, and that's why there was 120v flowing through the ground wire. That short causes the GFCI to cut the hot. If you break the hot, then there's no more current on that ground wire.
Unless stepping on the cable-way actually breaks the ground first and then connects it to the hot. That would be one impressive failure.

 

[DuckJordan]

In response to the people who claimed that the tour hadn't done their frequency co-ordination, They did. they are in our venue right now. In their rider they requested a frequency check for open channels that the venue was required to perform and get back to the company about. Fort worth did not do what the rider requested. Not to mention how much crap we had to fix when they pulled in to our venue straight from fort worth. I don't know about their crew but feeding camlock connections in one strand at a time (after cutting the e-tape that was holding it together as a snake is B.S.) not to mention running the first electric soco in to the bottom of the box instead of starting with the 5th electric was a bunch of crap.

This is a huge rant type issue, but It would be wise for people who don't know about a specific event or venue to not stick their noses in. (people like me who work in venues that touring shows come in may end up correcting you).

As far as mic issues go, everything has been working fine except for some minor issues tying their com system in to ours (our building is working with original old system clear com with no preamp for their newer setup).

My thing with mics is if they sound bad mic'ed but sound good without it, no mic. Granted everyone from my high school was required to project into a 400 seat venue with not so great acoustics.

 

[themuzicman]

I want to second most of what DuckJordan said...

Wizard of Oz has had some issues this latest tour out - being bumped down to one overstuffed truck and not travelling their own PA is the least of their problems. I got to see some of their rig when I was in prep for my show and am not surprised that they are having some issues. Changes were made, not enough tech time was given and they are having to make changes on the fly and on the road with a schedule almost entirely of one-nighters. It's a rough time for them.

RF Coordination for tours is a beast, especially when you're a one man audio department. For my show I ran an IAS report that would give me RF that would work in 80% of my venues with no changes, had no intermods, and had enough space that I could use spare channels on the report to counter any issues in the remaining 20% of venues. If I was put into the position Wiz was put in to, I could say that it would probably be a little rough...just trying to defend the position they were put in to a little.

 

[DuckJordan]

I want to second most of what DuckJordan said...

Wizard of Oz has had some issues this latest tour out - being bumped down to one overstuffed truck...

Correction 2 overstuffed trucks (almost lost munchkin land)

 

[themuzicman]

Oh wow! Two trucks is pretty cool then. The pack I saw looked tiny - though once you add in lighting and audio two seems more reasonable.

 

[Les]

Yeah, me and the twin girls I was with (Yep!) felt very sorry for the sound guy/crew, regardless of what the issue was.

I, being experienced with tech, didn't place blame on the venue or anyone for that matter. I just personally wished they had been turned off and left off. The girls (being non-technical) thought it was kinda funny. I, on the other hand could cut the tension with a knife.

One thing that was purposeful that bugged me, though unrelated to sound, was their use of followspots. Every principle was followed, always. On top of that, the venue was hazed for some reason, so the beams from the spots were continually within my peripheral vision. That's more of a personal thing, but an interesting design choice none-the-less.

To end on a lighter note, the cast didn't miss a beat during any of the sound problems, and their use of projections and scrim during the tornado scene was pretty awesome. The sound guy also apparently didn't leave the console to bang his head against a wall. I can't say that I have that much grace.

 

[DuckJordan]

Forgot to mention he is no longer working with that company...(the sound guy that is)

Sent from my ADR6300 using Tapatalk

 

[DrPinto]

It was my understanding that the hot shorted to the ground, and that's why there was 120v flowing through the ground wire. That short causes the GFCI to cut the hot. If you break the hot, then there's no more current on that ground wire.
Unless stepping on the cable-way actually breaks the ground first and then connects it to the hot. That would be one impressive failure.

The power came from the wall, through a trough, and to a couple of outlet boxes. I was plugged into the outlet boxes. If the hot wire shorted to ground in the trough, even if I was using a GFCI and it tripped, the power would have kept flowing through the ground wire until the breaker in the house tripped. The trough looked like something in the picture only I think it was metal - it was hard to tell because it was covered with tape.

 

[Lambda]

The power came from the wall, through a trough, and to a couple of outlet boxes. I was plugged into the outlet boxes. If the hot wire shorted to ground in the trough, even if I was using a GCIF and it tripped, the power would have kept flowing through the ground wire until the breaker in the house tripped. The trough looked like something in the picture only I think it was metal - it was hard to tell because it was covered with tape.

Ah, so the short was before the outlet. You're absolutely right, I think in that scenario the GFCI would have done nothing. The only thing that would have saved your mixer there would have been a crowbar circuit, a device that can detect faults like this and hard shorts the power until the breaker blows, ensuring the safety of equipment on the circuit. They're designed to protect against overvoltage, but one could be built to trigger on practically any condition, including a ground fault. But with the ground actually hot, and therefore no ground reference, I wonder if such a circuit would even work.
A interesting failure indeed.

 

[Chris15]

This situation really does demonstrate why the best place for an RCD / GFCI is on the switchboard...

In that instance it would have tripped because there would have been a current flowing out the active that was not returning via the neutral...

 

[Lambda]

This situation really does demonstrate why the best place for an RCD / GFCI is on the switchboard...

In that instance it would have tripped because there would have been a current flowing out the active that was not returning via the neutral...

It may have tripped, but it would have disconnected the hot, right? Or does it disconnect the hot, neutral, and ground? With the current flowing through ground, then disconnecting only the hot wouldn't have done much.

 

[DrPinto]

Ah, so the short was before the outlet.

Exactly.

I was wondering if there was anything I could do to protect my system if this happened in the future. I could use a power strip with a diode in the ground line (if they even make something like this). That would have worked.

Those 5 seconds it took for the breaker to trip could have been much messier. All my microphones were wired. I was also using a direct box on a guitar. I hate to think what could have happened if someone was holding a microphone or playing the guitar at the time.