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Author Topic: How Hot is Too Hot for Amplifiers? Martin McCaffery Film God Posts: 2481 From: Montgomery, AL Registered: Jun 99 posted 09-06-2019 03:22 PM                        The AC in our 35mm booth where the sound rack resides died. Can't fix it, waiting on a new one. We're scheduled to have close to 100 degree weather for the next week. This is a 1941 building, so the booth is a concrete bunker that the sun beats down on all day. I've got several fans blowing in and through the rack. I've taken the ReadyNas storage down to the digital booth (whose AC is fine) and hooked it to the projector. So that is protected. How much heat can a CP650 and QSC amps put up with? Are there any signs that they are overheating? Do they have safety cut offs? We'll run about 6 hours on Sat and Sun, 4 on Friday and 2 during the week. How worried should I be and is there anything else I should do?  |  IP: Logged Frank Cox Film God Posts: 2234 From: Melville Saskatchewan Canada Registered: Apr 2011 posted 09-06-2019 04:06 PM                        Any way you could use a portable air conditioner like this: Maybe stick the exhaust hose out the door or something? Even if it exhausts into the rest of the building you'll still be cooling the part of it that matters.  |  IP: Logged Jarod Reddig Jedi Master Film Handler Posts: 513 From: Hays, Ks Registered: Jun 2011 posted 09-06-2019 04:58 PM                     The CP650 is rated to operate at a range of an ambient temp of 32* F to 104*F. I think a constant fan on it may get you thru but would be riding the line .  |  IP: Logged Jim Cassedy Phenomenal Film Handler Posts: 1661 From: San Francisco, CA Registered: Dec 2006 posted 09-06-2019 06:48 PM                     I had a similar situation (No AC, old concrete-bunker type booth, hot summer weather, etc) many years ago. I have no idea what the booth temps were, except to say that it was HOT, since we were running change-overs & carbon arcs, which meant I had to stay in there. I got through the weekend by running out & buying two cheap window type "box fans" at a local K-Mart. One was placed so that it was blowing into the amplifier rack, the other was to keep ME from overheating. The fans were 20" box-fans, similar to this:  |  IP: Logged Martin McCaffery Film God Posts: 2481 From: Montgomery, AL Registered: Jun 99 posted 09-06-2019 07:10 PM                        The portable AC is plan B. The Boxfans have been supplemented by a high-powered circulating fan and a window fan hanging from the back of the rack. Kept it down to 98 in the rack, so hope to make it through the next couple of days.  |  IP: Logged Jack Ondracek Film God Posts: 2348 From: Port Orchard, WA, USA Registered: Oct 2002 posted 09-07-2019 02:16 AM                        The QSC amps I have shut down if they get too hot. I don't know what that temp is, but if the internal fans quit they will reach that point and will protect themselves. We found out the hard way that our Barco projectors don't like temps over 104. They'll shut off the lamp if they get to that point.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-07-2019 08:25 AM                     I had a site in Nevada where 100 degree heat is also common where the heat sinks on the DCA amplifiers were completely plugged up with dust and no air was flowing through them at all (See Picture). They still ran fine, but on a service call I noticed that the front of them was rather warm. So I stayed and pulled them out that night one by one and cleaned them out. That they never shut down is very good testament to how well designed those amplifiers actually are. Older QSC amplifiers will simply shut down and the fan will go into high speed mode. So if you hear the fans a roarin, then you know things have gotten too hot. But as far as the rest of the stuff in your booth I can not say. NEC projectors will shut the lamp down if the ambient temp gets too high or you lose your exhaust blower. The ICP module is designed to throw a high temp error if the FPGA over heats. So if you see that on your projector readout, trouble may arise. Can't speak for the CP-650, since the one's I have had fail were due to power supply failure. But a lot of heat is bad for anything electronic...  |  IP: Logged Carsten Kurz Film God Posts: 4340 From: Cologne, NRW, Germany Registered: Aug 2009 posted 09-07-2019 08:42 AM                     I'd be careful about the CP650 - also because a defect will not be easy to compensate. Is there head-room around it in the rack? What type of QSC amps are this? The old USA series are tanks. As a safety measure, check air inlets and outlets and fans for gunk and clean them. I guess you should be fine with additional venting. Maybe you can leave the fans running over night (just make sure it switches off automatically in the morning by using a timer-switch). We blow in cool air during nights in hot summer times. I do know that some nights lack cool air. - Carsten  |  IP: Logged Martin McCaffery Film God Posts: 2481 From: Montgomery, AL Registered: Jun 99 posted 09-07-2019 02:19 PM                        95 today with a 103 heat index. Amps are 3022's. Pretty clean. The internal fans would probably be more efficient with a cleaning, but the vents are all completely clear. Fans galore blowing on the rack. The 650 has plenty of headroom. We have a half an hour between the end of our 5:00 show and the beginning of our 7:30 show, so I'll kill the rack for awhile and let it cool down. I don't know how this theatre survived between 1941 and whenever we put in this AC unit (2009?). Not built for the care and comfort of the projectionists.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-07-2019 03:08 PM                     quote: Martin McCaffery I don't know how this theatre survived between 1941 and whenever we put in this AC unit (2009?). Not built for the care and comfort of the projectionists. Everything in the booth back then was a heat generator. All the tube audio equipment and carbon arc lamps. Not to mention the motor-generator or big sil tube rectifiers...Often, the only cooling coming into the booth was if the operator left the port windiws open between shows. But then he'd be violating the fire codes back then... BTW: Here in Belle Meade, TN it's only 84 out. You aren't that much further south from us... Mark  |  IP: Logged Martin McCaffery Film God Posts: 2481 From: Montgomery, AL Registered: Jun 99 posted 09-07-2019 04:03 PM                        Mark: I worked in lots of those booths in DC before I came here. By the time I was working (70's-80's) they all had AC, except, if I recall correctly, a couple of porno theatres and a drive-in or two.  |  IP: Logged Marcel Birgelen Film God Posts: 3357 From: Maastricht, Limburg, Netherlands Registered: Feb 2012 posted 09-08-2019 02:57 AM                     In a modern booth, that looks more like a room full of IT equipment rather than a traditional projection booth, an AC is almost mandatory. This IT equipment is simply a lot more picky than most of the professional AV equipment. I remember plenty of booths in the 35mm age, that didn't really have any AC, if you were lucky, there was a steady supply of fresh air from the outside... It was more important to keep it free from dust and oil fumes than to keep it cool. I think for most of those amps, it's more important to have a good airflow than the lowest inlet temperature. They need to get rid of their heat, so if there is no airflow possible, due to dust and gunk covered heat sinks and/or ventilation holes, the inlet temperature doesn't matter much. You could operate those in the open air on the North Pole and still face potential overheating...  |  IP: Logged Marco Giustini Film God Posts: 2713 From: Reading, UK Registered: Nov 2007 posted 09-08-2019 07:22 AM                     I have always liked the DCA airflow design. No filters, no fine grilles that can clog. Once a year I would blow compressed air from the back (manually holding the fan from spinning) while a colleague would hold a funnel attached to a vacuum cleaner which would cover the whole front grille.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 09-08-2019 11:48 AM                     quote: Marco Giustini I have always liked the DCA airflow design. No filters, no fine grilles that can clog. It depends on the type of dirt thats in the air and where you are located as to weather your amplifiers will clog with dirt or not. My picture above is proof that DCA's will OBVIOUSLY clog. The location was north central Nevada. And the building had well filtered HVAC system with a service contract. So those filters got changed quarterly. And it's difficult to tell if they are clogged without removing the amp and opening it up because of a cardboard divider in there. The clue in my case is they were quite warm when they normally are not. Four of the booths were ten years old and two booths were two years old. The sharp edges of the heat sinks are good catch point for dust bunnies which turn into what you see above. quote: Martin McCaffery Mark: I worked in lots of those booths in DC before I came here. By the time I was working (70's-80's) they all had AC, except, if I recall correctly, a couple of porno theatres and a drive-in or two. Martin, I believe a lot fo the theaters back then had water chillers instead of air conditioning. At least in the Chicago area there were. Chillers were quite common until water became expensive and they installed air conditioning... Mark  |  IP: Logged Steve Guttag We forgot the crackers Gromit!!! Posts: 12814 From: Annapolis, MD Registered: Dec 1999 posted 09-08-2019 01:32 PM                     What QSC "gets" that most other amplifier and equipment manufacturers, in general, do not is that their amps vent from rear to front! Conventional equipment takes cool, unfiltered air, blows it into the rack where it heats and pollutes other equipment with the dirt. With QSC, it takes air out of the rack and pumps it into the booth, where the heat can be better dealt with. I, typically, take it a step further by putting filtered air blowers in the bottom of the rack so clean cool air goes into the rack so the amps (and other equipment) can draw it back out. Also, by pumping more air in than the amps pull out, you pressurize the rack slightly so dust doesn't come in and settle. The only real downside is that most operators/managers don't clean the filters so they will eventually clog. The filters I'm now using, Middle Atlantic "FILTER" is external and a large sponge like filter that is easily seen and draws attention to itself as it clogs (you can count the number of fans that reside behind it...typically 2 or 3).  |  IP: Logged

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