Fire Alarm Cut Off

Re: Fire Alarm Cut Off

John Roberts said:
This concept has been around for a while and there are commercial solutions available when designing new systems.

I am not enthusiastic about McGyvering a bunch or relays to amps without knowing that his particular regulations call for.

We're not talking about Kansas anymore (UAE).
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Agreed, there are power switching/sequencing devices and audio processing devices commonly used in commercial/professional audio systems that incorporate the ability to take a dry contact closure, GPIO input, TTL logic or similar from a life safety system and either turn off the power to the related audio devices and/or mute the audio. In fact some devices have connections intended specifically for this purpose and some can provide a form of confirmation via dry contact closures, logic grounds or low voltage DC outputs. But you have to know what is actually required before you can determine what may or may not be a viable solution.
 
Re: Fire Alarm Cut Off

mike bogdanski said:
Gentlemen...............As the OP stated,he needs to disable the venue audible...........is that correct ?
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Thanks for your concern. I think I could have been much clearer with the situation, my apologies. The request to link the PA system to the fire alarm comes from the building the venue is based in, and these people comply fully with local codes. My involvement with the Alarm is strictly limited to automatically muting the system. A local fire alarm contractor is involved and I have spoken to them.

The contractor was happy to give me on of a number of different signals (I cannot remember all types) and were most enthusiastic about a 24v Normally On signal. They were happy to have this signal triggering the desk muting via a GPI, however this functionality does not work on our desk and if it did I don't think it's a great idea as it could be disabled by accident relatively easily.

I don't like the idea of a system to power off amps or processors as the wiring for this would require modifying a hired power distro or building something non-standard. I also retain some superstition about powering off amps /processors without muting the amps. The simplest option to implement would be a box that sat between the line level outputs of the stage rack and the inputs of the processors, doing nothing but muting. I have been unable to find such a box, and was hoping someone would know of one.
 
Re: Fire Alarm Cut Off

Jon Pusey said:
Thanks for your concern. I think I could have been much clearer with the situation, my apologies. The request to link the PA system to the fire alarm comes from the building the venue is based in, and these people comply fully with local codes. My involvement with the Alarm is strictly limited to automatically muting the system. A local fire alarm contractor is involved and I have spoken to them.

The contractor was happy to give me on of a number of different signals (I cannot remember all types) and were most enthusiastic about a 24v Normally On signal. They were happy to have this signal triggering the desk muting via a GPI, however this functionality does not work on our desk and if it did I don't think it's a great idea as it could be disabled by accident relatively easily.

I don't like the idea of a system to power off amps or processors as the wiring for this would require modifying a hired power distro or building something non-standard. I also retain some superstition about powering off amps /processors without muting the amps. The simplest option to implement would be a box that sat between the line level outputs of the stage rack and the inputs of the processors, doing nothing but muting. I have been unable to find such a box, and was hoping someone would know of one.
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you need a few (one for every audio line that you want to mute) of these ST-RX2 ‐ Audio Routing Switcher ‐ 1x2
and then ask the fire alarm contractor for a "dry contact" (very standard) and you're good to go.
these act as a relay but are designed to switch the audio between sources without a pop. of course in your case you're switching from DSP to nothing...
if you can insert it between the console and the DSP you're good to go.. if you can't then you should think about hiring someone who knows what's going on.

Jason
 
Re: Fire Alarm Cut Off

Jon Pusey said:
The contractor was happy to give me on of a number of different signals (I cannot remember all types) and were most enthusiastic about a 24v Normally On signal. They were happy to have this signal triggering the desk muting via a GPI, however this functionality does not work on our desk and if it did I don't think it's a great idea as it could be disabled by accident relatively easily.
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You might have to consider that the normally on/normally closed condition means that it will be the loss of the 24VDC rather than the application of it that should cause the system to mute. If you use a device that relies on the application of DC voltage or a contact closure to mute the audio then that may require an intermediate device to modify the control signal type and/or action. That is why you want to be sure to coordinate the control form being provided.

For example, the Radio Design Lab devices that Jason noted appear to require a TTL logic input to mute, thus with a 24VDC normally on control signal you may require something like a 24VDC operated, nomally closed relay wired between Trigger and Ground on the RDL devices. That realy would then be held open by the alram system control signal until an alarm, at which time the 24VDC control signal would stop and the added relay would provide a dry contact closure to trigger the audio mute.


Jon Pusey said:
I don't like the idea of a system to power off amps or processors as the wiring for this would require modifying a hired power distro or building something non-standard. I also retain some superstition about powering off amps /processors without muting the amps. The simplest option to implement would be a box that sat between the line level outputs of the stage rack and the inputs of the processors, doing nothing but muting. I have been unable to find such a box, and was hoping someone would know of one.
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Do the processors have external control inputs? If they do that would seem likely to avoid having to externally mute 21 audio lines.
 
Re: Fire Alarm Cut Off

In the US here in Cali, we would design and use Listed 24V relays, that would either open the line level circuits or short them. Find out if they can give you an alarm dry contact out of the FACP and use what is called a PAM-1 relay, available via most fire mfr. including Siemens and all the major players. This dry contact would then be circuited thru a listed 24VDC power supply and cause the PAM-1 relays to close on alarm shunting or opening the line level circuits. Notifier, Simplex, Honeywell and Siemens all have something similar in their product line up that will accomplish what you are wanting to do...you can also use those to trip a larger contactor if needed to shut down larger loads, however following the Codes we always use a listed relay assembly as the initial interface to the fire alarm system and adjunct contactors, relays, etc. for things down stream. If the local authority wants that circuit "supervised" there is a bit more interface needed to the fire alarm system and a relay with an end of line resistor need so that if power failed the fire alarm system would send out a supervisory signal to alert staff that , that particular function, auxiliary action has failed.
 
Re: Fire Alarm Cut Off

Daniel Levi said:
If you can get it in America this would probably be perfect Formula Sound - Guardian MK2 , Specifically designed for what you want to do.
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You can duck the audio like that device does using just about any DSP with control inputs or even with a few Radio Design Lab devices, but the elephant in the room is still what code and the AHJ actually require as that is what defines what you want to do. For example, that would not suffice for the one AHJ I encountered that insisted we power off the amps, that's a job for a power contactor, sequencer or controller.
 
Re: Fire Alarm Cut Off

It's taken me this long to realize (after much googling) that "AHJ" isn't "Alternative Health Journal" :)

I've dealt with the "Fire Marshall", Department of Building and Safety (DBS), The Electrical Inspector, etc..

Anyways, a few jobs ago the electrical contractor just provided us outlets that were on fire-panel actuated contactors. We just did a normal rack install and never had to worry about dealing with any of it as the moment the alarm sounded the entire rack was powered off. (I eventually moved the system processor to a UPS because they kept testing it while I was trying to program, but all six outlets and the amps plugged into them lost power instantly.

Worked better than some sequencer rigs I've done before as fire-marshals would get antsy at the delay while it cycled down the steps.

-I had them add a couple more to dump the two 20A circuits on stage so backline and monitors would die too. The effect was quite good as emergency lights would kick on as well as the strobes and buzzers at the same time as all sound stopped cold. (you really need to grab drunk-people's attention sometimes)

-now if only you could get something to stop a drummer suddenly, -a trapdoor wouldn't work as I would have been tempted to use it way too often :)
 
Re: Fire Alarm Cut Off

Craig Hauber said:
-now if only you could get something to stop a drummer suddenly, -a trapdoor wouldn't work as I would have been tempted to use it way too often :)
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I think a nice sharp "swinging blade" of some sort-right about neck height would be a good idea.

Let's see how fast the drummer can react when the rest of the band stops playing---------------------

OOPS-to slow-any drummers int he house?
 
Re: Fire Alarm Cut Off

David Sturzenbecher said:
Killing power on vintage tube amps will surly make the talent happy!
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It's no different than the main power toggle switch on those vintage amps. Schematically it's usually between the power cord and the power transformer, using the switch is no different than killing an upstream breaker.

-Also it still has neutral and ground connection so all the electrons can still drain out properly :)
 
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