Emergency/panic mute?

Per Søvik

Per Søvik

Graduate Student
Jan 31, 2012
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Norway
First a confession; I really screwed up the other day, here's what happened:

Setting up a show on my PC for a Behringer X32, I set the monitor sends to unity, making several scenes with different mute patterns and effect settings. I routed the monitors through some matrices, again (foolishly) setting the matrix sends to unity. Then I set the group sends etc. to recall safe modes (but missed the matrix safe). Having everything set up, I loaded the show, pulled the matrix sends down and turned the monitors and amps on. Proceded to set levels, and the monitor sends ended up at around -30dB (referred to unity). First act on stage, quick line check and went to the scene for that act. Instant full blown feedback of course, luckily the monitors were far away from the people on stage, but they probably got 2000Hz at 125dB. Luckily I had the matrixes selected, so a quick sweep with my hand took care of it.

I've been thinking, and except for resolving never to do a stupid thing like that again, I also realize that all this digital stuff with layers, remote controls, etc. is making us quite vulnerable to situations where we might be up shit creek without a paddle in immediate reach. Lasers, light desks, lifts etc. all tend to have big, red, easy to hit emergency buttons or cut-offs. Audio equipment, not so much.
1: Should all (digital) desks have a big, red, mute all outputs button?
2: Should there be a mute all outputs switch input?
3: Should there be network mute switches? I'm thinking something like an extender/repeater box that you can plug into the network that will mute all sound while still maintaining sync so there is no loss of sync noise, maybe too complicated? Maybe something like this with a kill switch on top?

Any thoughts? I know there are implementations of the theme in some theatre installs etc.
 
Re: Emergency/panic mute?

Per Søvik said:
they probably got 2000Hz at 125dB. Luckily I had the matrixes selected, so a quick sweep with my hand took care of it.

1: Should all (digital) desks have a big, red, mute all outputs button?
2: Should there be a mute all outputs switch input?
Click to expand...

There's nothing like 125dB to liven up an event. :D~:-D~:grin:

This would only help in situations of user error where the console remained functional but my first through was just to set up a globally scene scene safed softkey / UDK / whateveryourconsolecallsit as a mute group, with either all inputs, all outputs or both assigned to it.

I've seen footswitches for vocalists that short pins 2 and 3 of the mic line, is it OK to mute outputs like this?

Chris
 
Re: Emergency/panic mute?

If you screwed up the scene build, what's saying you didn't screw up the mute build?

While it would be nice in a case of panic to have a 'mute everything' button available, it would have to really mute everything to be effective. And if that mute switch is activated, you've got NO sound. Now imagine that switch got flakey on you. How wonderful might that be?
 
Re: Emergency/panic mute?

Been there, done that with a famous artist :(

The support act 'restored' some connections on the stage that I wasn't aware of.

Scene was stored with monitors up. Recalling - Painfull feedback in a fully seated venue! I killed the desk and ran down to shut of the amps and fix the cause of the error.

At that moment I really wanted that big red emergency button you can find on machinery.

Lesson learned and it has never happened again......so far.

With the x32 it should be possible to program a controller or device to mute/dim outputs with the touch of one button but for generic solutions a fricking huge red button controlling power to monitors is the way to go in my opinion ;)
 
Re: Emergency/panic mute?

A couple of things.

1. I have a default scene set up that I use, scene number 001 that has all of my default patching, labels, and groups set up. This also contains a couple of mute groups, including a MUTE ALL which has every input and output channel assigned to it. Hitting this mute group kills everything on the console.

2. My default scene set up always has the mix output channel faders set at infinity with the channel on/unmuted. When setting up a show, I want (myself and especially my more novice techs) to make an active decision of where to set the monitor levels, and not just have them up by default.
 
Re: Emergency/panic mute?

Per I have had the same feeling of panic in my case it was a mute/tuner pedal for a guitar that the battery ran out during the spoken word part of an event un mute the band on a per channel basis (hadn't bothered with setting up a mute group), switched layers to fade down presenter fade up video sting and all hell broke loose 'cause the poxy guitar was lying on a wedge worst 3 seconds of my life behind a sound console, now if I'm on more than 1 layer you bet there is a "mute all" button and it mutes everything even if it's not patched anywhere you never know if someone's going to be helpful and repatch something for you.
 
Re: Emergency/panic mute?

Brian jojade said:
If you screwed up the scene build, what's saying you didn't screw up the mute build?
Click to expand...

Yes, that's the thing, I always (except when I screw up) set mute group 1 as mute all, have safe output levels between scenes etc.(again except when I screw up).

Robert Lofgren said:
With the x32 it should be possible to program a controller or device to mute/dim outputs with the touch of one button but for generic solutions a fricking huge red button controlling power to monitors is the way to go in my opinion ;)
Click to expand...

Yeah, that's probably the way to do it. I actually have a four outlet pad with a kill switch in my garage/workshop/(overcrowded junk storage facility useless for all other intended purposes :(~:-(~:sad: )

And I just realized my solution. I'm going to build a patch panel for my rack (X32Rack, S16, IEM transmitters, Rack PC, UPS, Amps), and I'll include an array of output shortening relays that can be operated by a remote kill switch.
 
Re: Emergency/panic mute?

Of course, the next problem will be when I turn up the faders, get no sound, turn them up more and then realize that the kill switch is engaged and yank it up without turning down the faders :lol:
Chris Nixon said:
I've seen footswitches for vocalists that short pins 2 and 3 of the mic line, is it OK to mute outputs like this?
Click to expand...
Yes, no problem, just put a very small cap and a resistor across the switch to prevent any switching noise ( 22uF/100Kohm or thereabouts, need to do the maths for the particular output impedance not to disturb the normal signal). Of course, a foot switch with a long lead could induce some noise, but probably not a problem with line level signals.
 
Re: Emergency/panic mute?

Per Søvik said:
Yes, no problem, just put a very small cap and a resistor across the switch to prevent any switching noise ( 22uF/100Kohm or thereabouts, need to do the maths for the particular output impedance not to disturb the normal signal). Of course, a foot switch with a long lead could induce some noise, but probably not a problem with line level signals.
Click to expand...

Cool, I've been thinking of making a two channel one of these to put between the outputs of the console and the PA, in case I need to reboot or repatch the console and can't easily switch off the PA from FOH.

Were do I need to look to find out about the maths for suitable capacitors and resistors?

Chris
 
Re: Emergency/panic mute?

Justice C. Bigler said:
A couple of things.

1. I have a default scene set up that I use, scene number 001 that has all of my default patching, labels, and groups set up. This also contains a couple of mute groups, including a MUTE ALL which has every input and output channel assigned to it. Hitting this mute group kills everything on the console.

2. My default scene set up always has the mix output channel faders set at infinity with the channel on/unmuted. When setting up a show, I want (myself and especially my more novice techs) to make an active decision of where to set the monitor levels, and not just have them up by default.
Click to expand...


My method as well. The first MUTE group I set up on the Expression was for all channels and all things. Other MUTE groups include all vocals, and all backline. They come in pretty handy at times.
 
Re: Emergency/panic mute?

Chris Nixon said:
Cool, I've been thinking of making a two channel one of these to put between the outputs of the console and the PA, in case I need to reboot or repatch the console and can't easily switch off the PA from FOH.

Were do I need to look to find out about the maths for suitable capacitors and resistors?

Chris
Click to expand...

I wrote uF, it should of course be pF. Basically, the value of the capacitor should be so small that it puts the cutoff frequency in the calculation so high that there is no phase influence at 20 kHz. Using the RC formula Fc=1/2piRC , if the output impedance R and the capacitor value C result in a Fc above 100KHz, the phase influence is minimal. It is further reduced by the shunt resistor, and frankly just having a shunt resistor across the switch is enough in most cases to avoid any switching noise.

However, calculating the influence of the capacitor, assuming 300 ohm output impedance: 1/(2x3.14x300x22E-12)=22MHz. Even with an output impedance of 30 KOhm and a more common 47pF cap, the influence will be negligible, but the shunt resistor will steal a dB at those values.
Of course, any DC offset in the signal will still cause a noise, so then a capacitor in series with the switch need to isolate that, and that design is too complicated for me, but still the same formula using output impedance and capacitor value, just now it is high-pass and the frequency need to end up low enough so that the entire signal is passed trough the switch, 22 or 47 uF is probably fine.
 
Re: Emergency/panic mute?

Thank you Per, that's a much more detailed reply than I expected. :razz:

It'll take me a while to get my head round that, I've only made very simple circuits before but the output shorting mute box has been in the back of my mind for a while so it might be a good motivation to learn more...

If this was being used with varying consoles with differing output impedances, how much of a problem would that be? Is there much variation in output impedance?

I'd like a 2 in 2 out box, maybe 3/3, a bit like a comms box or a DI, with toggle switches that have covers over them.

Sorry for sort of stealing your thread. :D~:-D~:grin: On that topic though, would it be relatively simple to make one switch control multiple channels?

I think I found the button... 95 mm should be enough...

Large Palm/Foot Operated Switch : Control Stations : Maplin Electronics

Chris
 
Re: Emergency/panic mute?

Chris Nixon said:
If this was being used with varying consoles with differing output impedances, how much of a problem would that be? Is there much variation in output impedance?
Click to expand...

Cutoff frequency is inversely proportional to output impedance but I wouldn't expect output impedances to typically be more than a few hundred ohms. A reasonably sized capacitor will get the cutoff frequency well into the MHz so even a factor of ten change in output impedance would still have the cutoff frequency well above the audio range.

In short, nothing to worry about.
 
Re: Emergency/panic mute?

Chris Nixon said:
On that topic though, would it be relatively simple to make one switch control multiple channels?
Click to expand...

You just need a bunch of relays, operated from the same control signal. I'm sure someone that actually know about these things could point out a relay chip suitable for the purpose. There must be a suitable audio relay chip that is made specifically for the purpose, that will probably be the simplest.
 
Re: Emergency/panic mute?

Per Søvik said:
You just need a bunch of relays, operated from the same control signal. I'm sure someone that actually know about these things could point out a relay chip suitable for the purpose. There must be a suitable audio relay chip that is made specifically for the purpose, that will probably be the simplest.
Click to expand...
An active DI running on mains power should do the trick. No power - No sound.
 
Re: Emergency/panic mute?

Chris Nixon said:
Cool, I've been thinking of making a two channel one of these to put between the outputs of the console and the PA, in case I need to reboot or repatch the console and can't easily switch off the PA from FOH.

Were do I need to look to find out about the maths for suitable capacitors and resistors?

Chris
Click to expand...

One thing I really liked during the analog days was KT, and certain other graphics, that had either a mute switch or a volume control that went all the way down to zero, as it allowed me to listen to the actual outputs of a console on headphones during changeover, making patching or routing goofs a lot less likely.

This is something I sometimes miss when using digital consoles, and makes a great case for having remote control of the main DSP or matrix from FOH.
 
kristianjohnsen said:
One thing I really liked during the analog days was KT, and certain other graphics, that had either a mute switch or a volume control that went all the way down to zero, as it allowed me to listen to the actual outputs of a console on headphones during changeover, making patching or routing goofs a lot less likely.

This is something I sometimes miss when using digital consoles, and makes a great case for having remote control of the main DSP or matrix from FOH.
Click to expand...

Or route your mains through a matrix and mute the matrix. ...

Sent from my SCH-I545 4
 
Re: Emergency/panic mute?

Silas Pradetto said:
Or route your mains through a matrix and mute the matrix. ...

Sent from my SCH-I545 4
Click to expand...

I mentioned this in my post, snarkypants.

The dream of the "one device mixing system" that was hoped for when digital consoles showed up seems ever-elusive, always another piece of gear that would be cool to have!

With analog, FOH was a bunch of racks anyways, and the ability to mute the various outputs from outside the console was a nice feature to have. Edit: Silas, I see now you meant a mixbus matrix, not a hardware matrix unit. I almost always use a mix matrix as my final output bus, but it quickly eats up matrices if one is to dedicate one to each aux monitor send, also. Besides, one can still screw up the matrix routing. I think it's nice to be able to AFL the very final output of the mixer during changeover. Those old graphics made that easy.




Silas: I tried to edit my post yesterday, but it didn't "stick". This forum as some serious Internet Explorer-issues...

Anyway, sorry for my snarkiness. I see now that you meant a matrixmixbus, not a hardware matrix unit. I usually use a matrix bus as my final output stage from the mixer. However, matrix routing and inserts can still be screwed up, so for a absolutely foolproof check that everything is good to go during changeover, it was a nice feature of the analog graphics to be able to mute all the mains and monitors really quickly, and just AFL the outputs in headphones.
 
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