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Author Topic: Sound Rack Power Down Procedure Bill Yacey Film Handler Posts: 23 From: St. Albert, Alberta, Canada Registered: Feb 2011 posted 02-20-2011 02:20 PM                     Pretty much all commercial amplifiers nowadays are class AB2 or some variation of it. They draw very little current on idle. Even a 2000 watt amp doesn't draw more than around 1 amp @120V at idle. This amounts to about 120watts of power dissipation at idle, which could add up to quite a bit of power if there are multiple amps per theater in a multiple theater establishment.  |  IP: Logged Jonathan Seaman Film Handler Posts: 13 From: Norwich, Norfolk, UK Registered: Mar 2011 posted 03-06-2011 04:49 PM                     The theatre I work at has QSC amps in one of the screens and we switch them off using the switch on the front of the amp, then the main breaker for the sound cabinet. We have been doing this for around 10 years+ and the switches have never been replaced. On another note, it is probably best that you switch the amps off using the switches on the front as if you were to leave the amps switches to on, when you come to power the rack up the following morning if you switch the breaker on there is going to be a large in rush of power as everything powers up it could blow fuses, breakers or even damage equipment.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-06-2011 07:47 PM                        That will not happen if the system is properly engineered. I do agree it happens; just that it is a sign of a "work-around." Louis  |  IP: Logged Mike Blakesley Film God Posts: 12767 From: Forsyth, Montana Registered: Jun 99 posted 03-06-2011 11:29 PM                        We have all the amps plugged into a power strip and we use the switch on that to turn them all on at once. (QSC amps)  |  IP: Logged Jake Spell Master Film Handler Posts: 294 From: Johns Island SC Registered: May 2009 posted 03-07-2011 12:49 AM                     Ours is super easy, turn on QSC DCM, JSD-80, XD-10 and reverse to power down.  |  IP: Logged Brad Miller Administrator Posts: 17775 From: Plano, TX (36.2 miles NW of Rockwall) Registered: May 99 posted 03-07-2011 01:03 AM                     quote: Mike Blakesley We have all the amps plugged into a power strip and we use the switch on that to turn them all on at once. (QSC amps) A power strip??? How many amps do you have and what model?  |  IP: Logged James Wallor Film Handler Posts: 26 From: Houghton, MI, United States Registered: Mar 2011 posted 03-07-2011 02:14 AM                     I could kind of see it working on a power strip. Ours are power by a 2-pole...30 or 40 amp breaker, and we have six amps. So, essentially three amps on a single 40 amp breaker. So if they had three amps setup like L/R, C/S, RL/RR for a 5.1 setup, then perhaps.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 03-07-2011 06:47 AM                        Not to be nasty. . but. . if an amp has a failure in its power cord, it will take a 40 amp load to kick the breaker?? Louis  |  IP: Logged Scott Norwood Film God Posts: 8146 From: Boston, MA. USA (1774.21 miles northeast of Dallas) Registered: Jun 99 posted 03-07-2011 07:57 AM                        I'm with Barry: just get the power sequencer (or, more likely, two or more, depending on the power of your sound system) and be done with it. I have no idea why these are not popular with cinema systems. Most recent installed sound systems in non-cinema venues use them. And add the CP50 and CP200 to the list of processors that make a nasty and potentially speaker-blowing "pop" when powered on.  |  IP: Logged Mike Blakesley Film God Posts: 12767 From: Forsyth, Montana Registered: Jun 99 posted 03-07-2011 08:29 AM                        quote: Brad Miller A power strip??? How many amps do you have and what model? Brad - I was half asleep when I made that post, apparently. They are NOT plugged into a power strip, but there IS one wall switch that turns them all on at once.  |  IP: Logged Jonathan Seaman Film Handler Posts: 13 From: Norwich, Norfolk, UK Registered: Mar 2011 posted 03-07-2011 09:40 AM                     I have to say that I do partially agree with you Louis but I would have put our comment slightly differently. I would have put 'This should not happen if properly engineered.' Electricity is a dangerous and mysterious thing. Law in the UK requires us to have a system in place where if the fire alarm sounds then film sound is cut. This is done by a remote relay which is set to trip and cut power to the whole rack not just the amps. This is why we turn the amps off individually as when we switch it on in the morning we have to throw the breaker for the sound rack to on and then reset the relay. If we left amps on then when we fire the sound rack up the following would all come on at once. Dolby CP65 Dolby Digital Processor 5 QSC amps Hairing Aid Loop Amp. CD Player It is not a great idea to fire this all up at once. But each cinema has it's own start up and shut down sequence.  |  IP: Logged James Wallor Film Handler Posts: 26 From: Houghton, MI, United States Registered: Mar 2011 posted 03-07-2011 12:32 PM                     quote: Louis Bornwasser Not to be nasty. . but. . if an amp has a failure in its power cord, it will take a 40 amp load to kick the breaker?? Louis I don't remember the breaker size off the top of my head. it could only be 20amp. I was just using a value to explain the setup.  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 03-07-2011 03:50 PM                        Barry's setup sounds really great, but seriously, people. Don't you think just about everything out there is built with the reality that the building might suffer a simple power outage? Nobody would buy your stuff if it couldn't handle that. At most, I could maybe see turning stuff on in a particular order. Not everything is quiet on startup. For off... kill the breaker & go home. Oh... hopefully, your place was built with switch rated breakers, or you'll eventually have the same problem Louis was talking about with front panel stuff.  |  IP: Logged

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