my profile | my password | search | faq & rules | forum home

» Film-Tech Forum ARCHIVE   » Operations   » Film Handlers' Forum   » Sound Rack Power Down Procedure (Page 1)

This topic comprises 2 pages: 1  2

Author Topic: Sound Rack Power Down Procedure Steven Ferguson Film Handler Posts: 9 From: Burnaby, BC, Canada Registered: Oct 2010 posted 02-17-2011 05:01 PM                     I have a QSC MX 2000a Dual Monoaural Amp. When shutting down for the night, do I turn this off with the switch on the amp, or can I power it down with the master switches that power down the sound rack in it's entirety? I've seen it done both ways, but I've got a couple staff who swear adamantly it's way better for the amp to shut it down first. Thanks  |  IP: Logged Joe Redifer You need a beating today Posts: 12859 From: Denver, Colorado Registered: May 99 posted 02-17-2011 05:09 PM                        Doesn't matter. Either way it is cutting power. The caps in the amp may take a while to drain so the lights on the amp may stay on for a bit, but there is no harm in shutting everything down at once from the master breaker.  |  IP: Logged Steven Ferguson Film Handler Posts: 9 From: Burnaby, BC, Canada Registered: Oct 2010 posted 02-17-2011 05:23 PM                     Thanks!  |  IP: Logged Ron Lacheur Jedi Master Film Handler Posts: 650 From: British Columbia, Canada Registered: Feb 2002 posted 02-17-2011 05:29 PM                     Is there a master breaker for the rack there? If there is and everything shuts down at once, I don't think it would be an issue. I think QSC amps mute the output on power down anyways. We shut the amps down first then breakers off, because all the outlets in the sound rack are individual breakers and the processor turns off before all the amps are off.  |  IP: Logged Louis Bornwasser Film God Posts: 4441 From: prospect ky usa Registered: Mar 2005 posted 02-17-2011 06:02 PM                        The amp switch is not designed for daily use. You will be replacing it. That said, there are some inferior systems where the processor "pops" on shut down. (Sounds like a cannon in the auditorium.) Louis  |  IP: Logged Steven Ferguson Film Handler Posts: 9 From: Burnaby, BC, Canada Registered: Oct 2010 posted 02-17-2011 06:04 PM                     Ahhhh that makes sense. Yeah, we have three switches for the rack, and all can be flicked off simultaneously. And there is no 'pop' during power down, so it sounds like I'm all good.  |  IP: Logged Sean McKinnon Phenomenal Film Handler Posts: 1712 From: Peabody Massachusetts Registered: Sep 2000 posted 02-18-2011 12:10 AM                        I always liked the racks (big sky I think) that come with a built in contactorso that the entire rack can be switched on or off from the projection console. Very elegant IMO.  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 02-18-2011 05:56 AM                     We have four Amps in our Rack. When we switch them all on/off with the rack main switch, our fuses blow. We switch them off individually so we need to sequence them manually on power on after the main switch. An automatic power sequencer would be handy, but would also be another possible point of failure. Whenever possible, I would always switch off an amp individually before attached gear is switched off. These amps have huge capacitors and may still deliver bad spikes from the inputs. You may not always hear them, and you may not always have the same situation on attached systems. A blown speaker is a blown speaker. - Carsten  |  IP: Logged Bill Yacey Film Handler Posts: 23 From: St. Albert, Alberta, Canada Registered: Feb 2011 posted 02-18-2011 01:12 PM                     This is good advice. I used to be a partner in a live sound touring production company, the power amps were always the last thing to be powered up, and the first thing to be powered down, with the input gain controls always reduced to minimum. This eliminates any possibility of signal thump from other devices powering up or down while the power amps are still working. Powering up multiple high power amps simultaneously creates a very large initial current draw until the filter caps charge up. Powering down isn't a concern. The filter caps tend to absorb any inductive kick from the power transformers should the line voltage be shut off.  |  IP: Logged Barry Floyd Phenomenal Film Handler Posts: 1079 From: Lebanon, Tennessee, USA Registered: Mar 2000 posted 02-18-2011 02:57 PM                        At our church, we have a automated power sequencer that steps through the "powering on" and "powering off" of the various equipment in the sound, lighting and video booth. The mixing consoles, rack components, etc. are powered on first, the crossovers and equalizers are powered on next, and the amps for the auditorium are powered on last. When "powering off" the system, one push of a button and it automatically does everything above in the reverse order. Our amps are located in a closet upstairs behind the stage, so it's remotely hardwired from the booth. Ours is actually activated with a key lock switch as opposed to a button - mainly to keep "the people who say they know how to run a sound system" from messing with it.  |  IP: Logged Ron Lacheur Jedi Master Film Handler Posts: 650 From: British Columbia, Canada Registered: Feb 2002 posted 02-18-2011 05:20 PM                     quote: Louis Bornwasser That said, there are some inferior systems where the processor "pops" on shut down. (Sounds like a cannon in the auditorium.) Louis CP45 does this and powering the amp off first has put an end to the woofers over excursion and failure.  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 02-19-2011 06:32 AM                     As far as I know it depends on the amp. Some amps charge the capacitors slowly and avoid breakers tripping. Some other don't. DCAs for example should be safely shut down using the main breaker, QSC call the feature "Active Inrush Limiting". Another cinema I used to work for had Crown amps and you couldn't turn them on using the breaker or it would trip (they actually did for years, trying several times every day when the breaker would trip. Eventually the breaker... broke and an amp went up in magic smoke). I have always turned the amps off by their switches though.  |  IP: Logged Bill Yacey Film Handler Posts: 23 From: St. Albert, Alberta, Canada Registered: Feb 2011 posted 02-19-2011 10:28 AM                     Amps that have a switching power supply can have a ramp up time to charge the filters slowly, but more amps are of the older brute force power supplies, and these are the ones we need to be concerned about.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 02-19-2011 11:12 AM                     The charging of capacitors is only part of the problem Many amps use large torroidal power transformers and they have very high inrush currents until the core saturates I do all our soundsystems with all processing equipment left on all the time and just the amps being powered off On the large systems the entire thing is left powered up 24-7  |  IP: Logged Ron Lacheur Jedi Master Film Handler Posts: 650 From: British Columbia, Canada Registered: Feb 2002 posted 02-19-2011 09:14 PM                     That's how it was when I worked for Famous Players. The racks including the amps were left on 24/7. In the day and age of " going green ", doesn't your clients have an issue with the power bill? Or does idling amps draw next to nothing?  |  IP: Logged

All times are Central (GMT -6:00)

This topic comprises 2 pages: 1  2

Printer-friendly view of this topic

Hop To: Select a Forum: Category: Operations -------------------- Digital Cinema Forum Film Handlers' Forum Large Format Forum Ground Level Feature Info, Trailer Attachments & REAL Credit Offsets Category: Community -------------------- Film-Yak Film Handlers' Movie Reviews The Afterlife Bob Maar's Joke-A-Thon Category: Classified -------------------- Equipment and Supplies Wanted/For Sale Help Wanted/Seeking Employment Category: System -------------------- Software Beta Testing Forum

The Film-Tech Forums are designed for various members related to the cinema industry to express their opinions, viewpoints and testimonials on various products, services and events based upon speculation, personal knowledge and factual information through use, therefore all views represented here allow no liability upon the publishers of this web site and the owners of said views assume no liability for any ill will resulting from these postings. The posts made here are for educational as well as entertainment purposes and as such anyone viewing this portion of the website must accept these views as statements of the author of that opinion and agrees to release the authors from any and all liability.