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Author Topic: Amp situation critical Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 08-11-2005 02:56 PM                     Phil, 4670D I would not use in an "Iwerks" project but a 175 seat shoebox cinema they bi-amp nice at 630 or 800 HZ crossover point ....they where usually an improvement from a home made speaker or Music store unit with a 180 degree horn found in some international locations Crown CE amplifiers need to stay clean, and do not tolerate low voltage on power. How about Ashley amplifiers  |  IP: Logged Heath Dutton Film Handler Posts: 37 From: Montgomery, Alabama / United States of America Registered: Jul 2005 posted 08-11-2005 03:01 PM                     Hey Wolff, Unfortunately we have ultra-stereo analog processors, I have a feeling you fellas lucked out and got the digital package we are so jealous of. These processors use a pink-noise generator card, that we unfortunately do not have. I requested one once, but never received it. I do however try to use non-sync to achieve the same end, and it does work to a certain extent. But, some of these amps are a little too far gone, and others will have to have this process repeated a couple times a day to keep them "warm". Alternatively I have an old mini-disc player with pink noise on it, but it's a pain to wire it to an input every time I need pink noise. I may be wrong but I have the feeling that our humidity situation may be causing the excessive amp failures. Our AC ducts over the booth were removed a while back and since then I've noticed condensation on everything from port-hole windows to projectors. It could also have to do with the AC turning the booth sub-zero at night, and the fact that our exit doors no longer have weather stripping to speak of. The last two hurricanes both left the booth with rust on every projector (mostly on the dowser and gate pins). Needless to say we use alot of liquid wd-40. Everyone has been very helpful, and I will be checking the blueprints and looking into what QSC has to offer.  |  IP: Logged Gordon McLeod Film God Posts: 9532 From: Toronto Ontario Canada Registered: Jun 99 posted 08-11-2005 03:17 PM                     Many amps use ribbon cables or cables with amp/molex headers and if humidity is an issue then they can get corroded and make intermitent or poor contact  |  IP: Logged Richard May Phenomenal Film Handler Posts: 1057 From: Floral Park, NY USA Registered: Aug 2004 posted 08-11-2005 03:19 PM                     I have been installing the Crown CE series for about 6 or 7 years now. They did have a problem early with some of the amps pretty much exploding into flames. Since they fixed that though, I have had no problems with them. I do like the QSC amps, but for the price I will continue to stay with the Crowns. They have been extremely reliable. Out of the 400-600 that I have installed, I can remember about 10 or so that failed.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-12-2005 01:12 AM                     I like the 4670D's for smaller theatres not over 175 seats or there abouts and they sound even better bi-amped. In reality I've had about the same lick with all the power amos in this area if you take the number of amps out there VS the number that have failed. The amps in this area with the least problems seem to be the Ashleys. I think if you were to take a poll from each manufacturer you'd find the same failure rate with each company that you would with a ordinary light bulb. Mark  |  IP: Logged Wolff King Morrow Master Film Handler Posts: 490 From: Denton, TX, USA Registered: Feb 2004 posted 08-12-2005 04:21 AM                        Heath, we have the DSP 60S sound processors, so I think you're right on that. Bummer... I thought I had it rough with a few grumpy amps and a couple of bad spares, but y'all have a serious headache to contend with. BTW, I do have a very nice set of crown royals and a Dolby Digital setup on one of my screens, which has never even hinted at giving me any amp problems. I'm quite pleased with their performance and reliability in comparison.  |  IP: Logged Frank Angel Film God Posts: 5305 From: Brooklyn NY USA Registered: Dec 1999 posted 08-12-2005 05:39 AM                        Talk about reliabilty, we had four 70w Norleco Philips rack mounted tube amps in our small theatre. They were never turned off since 1970. They were only turned off recently because they had to be physically moved, but they still work. Norelco also made a sound mixing console and, believe it or not, an theatre electronic organ (four registers) that we had in our big house for a few decades. BGWs burst into flames. Regularly. So do the older Crowns. Anyone ever hear of Phase Linear amps? It was a company made up of a bunch of MIT guys. It was the first amp I ever bought and it has been in use for like 30 years. One channel died only a month ago. You would think they could make components more reliable today than they were able to back then, but I guess that is just not the case.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-12-2005 08:05 AM                     quote: Frank Angel Anyone ever hear of Phase Linear amps? It was a company made up of a bunch of MIT guys. It was the first amp I ever bought and it has been in use for like 30 years. One channel died only a month ago. You would think they could make components more reliable today than they were able to back then, but I guess that is just not the case. Actually I know the person behind the original Phase Linear amps, Bob Carver. It wasn't a "bunch" of MIT guys it was all him and just some assistants working for him. I worked in a Hi-Fi repair shop in the Chicago burbs for several years right after getting out of High School in the early 70's and repaired scads of them along with scads of Crown D-series amps. Phase Limears, mainly the 400 also took out many drivers in speakers when they blew. +/- 75 volts in the 400 and +/- 100 volys DC in the 700 and the fuses couldn't always act fast ehough to protect the speakers. I haven't seen a BGW flame out yet but I have seen a QSC shoot flames out its front! Phase Linears were not very reliable or very good sounding amps but they were among the first affordable high power home audio amps made. Actually semiconductors ARE more reliable today but manufacturers skimp and sometimes don't use enough of them for maintaining a decent SOA, or enough heat sinking to peoperly dissipate the heat generated. The Phase Linear amps are a prime example of an amplifier thats drastically under heat sinked. Some QSC's are also among the best examples of amplifiers without enough sinking in the 1200,1400 series and the USA series. Try running one though the standard FTC conditioning tests sometime......PHEW! Also keep in mind that the heatsinks can be and typically ARE the most expensive mechanical part of an amplifier that is properly designed, Krell amps are a good exapmple of amplifiers with alot of $$ tied up in just the heat sinks, but these amps also allow proper dissipation of the OP drvices without the use of any fan. BTW: Bob Carver sold the Phase Linear name and later went on to found Carver Corporation..... Mark  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 08-12-2005 09:46 AM                     I remember installing phase linear amplifiers in clubs and theme parks in the early 70's....my boss at the time, who is now retired on his patent royalties, designed cooling kits and low pass filters for the units....nothing was a problem for him, he would design some widget as a fix  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 08-12-2005 11:18 AM                     Its funny that you mention that Richard because any DC on the input of a Phase Linear usually mest instant destruction for both amp and speakers!! The low pass filter was definatly a needed thing.... Mark  |  IP: Logged Sam D. Chavez Film God Posts: 2153 From: Martinez, CA USA Registered: Aug 2003 posted 08-12-2005 01:22 PM                       Phase Linear = Flame Linear in this area.  |  IP: Logged Richard Fowler Film God Posts: 2392 From: Ft. Lauderdale, FL, USA Registered: Jun 2001 posted 08-12-2005 02:56 PM                     Smoke residue was easy to clean off the satin aluminum finish of the amplifiers  |  IP: Logged Heath Dutton Film Handler Posts: 37 From: Montgomery, Alabama / United States of America Registered: Jul 2005 posted 08-12-2005 04:56 PM                     Wolff, How did you get crowns on your Dolby Digital house? About a year ago I was told that they were considering replacing one of our large house racks with all crown amps and using those as spares. Perhaps this is what happened at your theater? We have never (as long as I've been here) had more than one spare. Of course it's gone now, lost to shipping or theft (which I will never know). The one good thing about our setup is that we have 2 Dolby Digital houses, one medium sized (2) and one large (16). This makes 2 my favorite house of course But unfortunately we have changed general managers twice since I heard last about the crowns, and apparently it never made it into the budget.  |  IP: Logged Wolff King Morrow Master Film Handler Posts: 490 From: Denton, TX, USA Registered: Feb 2004 posted 08-13-2005 02:10 AM                        The crowns were "donated". In other words, the company gave a demo and never bothered to pick them back up. This was 3 years ago I believe. BTW we also have 2 DD houses, both our largest screens.  |  IP: Logged Andrew Duggan Expert Film Handler Posts: 127 From: Albany, NY, USA Registered: Jun 2002 posted 08-15-2005 11:28 PM                        I've never had the chance to use any Crown amps in a projection situation, but I had the luck of having a CE1000 go up in smoke a few months ago at a club I work at, in mid show. It was awesome, and by "awesome", I of course mean "a complete nightmare". It's biased me more than a little bit towards the whole brand. Still waiting for my QSCs to die on me though.  |  IP: Logged

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