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Topic: The Amplifier You Install the Most

James Westbrook
Phenomenal Film Handler

Posts: 1133
From: Lubbock, Texas, Usa
Registered: Mar 2006

posted 06-04-2010 10:58 PM

The key word here is "months."

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Demetris Thoupis
Phenomenal Film Handler

Posts: 1240
From: Aradippou, Larnaca, Cyprus
Registered: Apr 2001

posted 06-05-2010 03:58 AM

I have also two cinemas with Peavey amps that were originaly installed from a foreign dealer. Only had one failure and that was excessive dry joins.
Dem

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Stephen Furley
Film God

Posts: 3059
From: Coulsdon, Croydon, England
Registered: May 2002

posted 06-05-2010 04:42 AM

During the time that I was projecting at Croydon the original amps, I can't remember what they were now, were replaced by Crown; it's the only place I've actually seen them. This was around the time when digital went in, and various other upgrades were made.

Didn't really have enough experience of them to form an opinion, good or bad. I turned them on at the start of the day, and they worked. Didn't sound better or worse than similar amps, at least not to my ear.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 06-05-2010 10:54 PM

Back when I entered this biz in the Chicago area it was McGhoan Electronics. I mainly found McGhoan PA amplifiers... even in stereo systems. Now McGhoan had a ong history of building record players for Montgomery Wards and branded amplifiers for the Chicago area Hi-Fi chain Musicraft. I'm sure that Sam has run into these in past years when he was installing Dolby gear around the Chicago area. I always figured they had some union connection of some sort and I can vouch that these amps were taken right out of the pages of the RCA Semiconductor book! Reliable they were... cheaply built they were but they did work. Hopefully most have been retired by now however I can imagine that a few have survived.

Oh, and today I install only QSC amplifiers... model dependent on the jobs budget r the existing equipment at the site. I also rebuild gobs of series 1 amplifiers

Mark

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Marco Giustini
Film God

Posts: 2713
From: Reading, UK
Registered: Nov 2007

posted 06-06-2010 12:51 PM

I have experience with Crowns amps dying in a smoky cloud passing DC to the speakers...

One of the QSC's that failed did so in a smoky cloud, though, but no DC to the speaker.

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Martin Brooks
Jedi Master Film Handler

Posts: 900
From: Forest Hills, NY, USA
Registered: May 2002

posted 06-06-2010 10:44 PM

quote: Steve Guttag
Crown burned their bridges with NUMEROUS failures. Having built-in crossovers and other "features" in the amplifier also means those functions fail when the amp fails or have to be replaced when the amp is replaced...etc.

That's too bad. I have a Crown D75 that's been in operation in my system at home for something like 33 years with absolutely not a single problem.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 06-07-2010 08:13 AM

Martin... If you replace it you will finally hear the music! It's an ancient design with many audible issues including very high transient intermod distortion. There were even better sounding amps in those days. Basically the same circuit as the D-150 and DC-300 just scaled down. Very slow high distortion input I.C. And Quasi complementary output stage with all the inherent problems of old school semiconductors.

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Joe Elliott
Master Film Handler

Posts: 497
From: Port Orange, Fl USA
Registered: Oct 2006

posted 06-07-2010 10:10 AM

We have about 70 Crown amps in the building with a fail rate of about 6 in the past two years. Now granted these amps are only 8 years old, but that doesn't seam too bad. However, I have experienced the DC hum to the speakers, and it generally travels through all the channels, and you have to disconnect the offending amp. That has happened twice out of the 6 amps that failed.

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Steve Guttag
We forgot the crackers Gromit!!!

Posts: 12814
From: Annapolis, MD
Registered: Dec 1999

posted 06-07-2010 11:56 AM

6 in the past two years? That is about 8.5%. Care to know how many DCAs I've sent back in the past decade out of the hundreds we've sold? Of those that got into service...I think it is either zero or 1. I've had one or two DOAs (needing just a quick fix...still frustrating though).

Steve

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Martin Brooks
Jedi Master Film Handler

Posts: 900
From: Forest Hills, NY, USA
Registered: May 2002

posted 06-07-2010 04:21 PM

quote: Mark Gulbrandsen
Martin... If you replace it you will finally hear the music! It's an ancient design with many audible issues including very high transient intermod distortion. There were even better sounding amps in those days. Basically the same circuit as the D-150 and DC-300 just scaled down. Very slow high distortion input I.C. And Quasi complementary output stage with all the inherent problems of old school semiconductors.

A bit off topic, but: before that Crown, I had a Fisher 500c receiver. It was definitely warmer but had more limited frequency response and a bit of hum on the bottom. I'm actually in the market for new equipment, but I have to say that I have been notoriously unimpressed by anything I've heard at retail that's reasonably priced. I actually hope that whatever I get to replace the Crown does sound a lot better so I won't regret the investment.

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Louis Bornwasser
Film God

Posts: 4441
From: prospect ky usa
Registered: Mar 2005

posted 06-07-2010 09:58 PM

We once sold an Ashly to a guy for home use. He tried 3 units in a row, complaining that they weren't loud enough. At 300 watts/channel, I rejected that as just wrong.

We sold him a D75 Crown. He was very happy. He asociated distortion with loudness.At full output distortion was over 40%. Louis

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Mark Gulbrandsen
Resident Trollmaster

Posts: 16657
From: Music City
Registered: Jun 99

posted 06-07-2010 10:31 PM

Louis,
I completely believe that!

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Tony Bandiera Jr
Film God

Posts: 3067
From: Moreland Idaho
Registered: Apr 2004

posted 06-08-2010 02:01 PM

quote: Demetris Thoupis
PS. And I don't compare testing an amp in the rain a test which validates which amp is best or not! They are not supposed to get wet. (although definately not saying that Yamaha amps are worth installing in cinema applications)

LOL I do. I have tested various amps by heat, cold, water and dropping from a height of three feet onto a carpeted concrete floor. So far only QSC's have survived the worst I could throw at them. Another good torture test is to feed it a square wave signal at about 4khz at full rated power. A lot of amps don't survive that test. [evil]

Bobby/Jonathan: I installed a pair of Peavey CS400's for two center/surround setups for Laemmle Theatres way back in the late 80's. One amp finally quit after about ten years and as far as I know the other one is still there. Small rooms so they don't have to work very hard. One thing I did notice and did not like about the Peaveys is how hot the transformer got even at idle. Since the houses used Cervin-Vega disco speakers behind the screen I have no opinion on how good/bad those amps sounded.

quote: Louis Bornwasser
We sold him a D75 Crown. He was very happy. He asociated distortion with loudness.At full output distortion was over 40%. Louis

I'll bet he's the same guy who equates the numbers on the fader with watts output too. [Roll Eyes]

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Jonathan Althaus
Master Film Handler

Posts: 435
From: Bedford, TX
Registered: Dec 2008

posted 06-30-2010 01:41 PM

Replaced a Peavey 800 last week, probably the first time in over a year.

About 2 years ago, we had 12 crowns installed, and other than the one we were trying to push double the load of what it could handle, did not have any go out. We get a premade rack last week (all Crown) for a digital install, and 2 have gone out in a 5 day span. Turns out these amps were made in China, whereas all our others were American made. After talking to Crown, they admitted they had a huge batch of amps with bad transducers.

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Jeremy Weigel
Phenomenal Film Handler

Posts: 1062
From: Edmond, OK, USA
Registered: Mar 2007

posted 12-27-2010 10:35 PM

quote: Jeremy Weigel
I still have one of them and have been debating whether it is worth trying to fix it.

quote: Tony Bandiera Jr
Jeremy, there was a bad run of MXa's that had a problem with the power switch and associated wiring. When it let go the forced air from the fan in concert with the natural dust build-up made for quite a show.

Contact QSC's service department with the amp's serial number, it is quite possible they will fix it at no charge if it was one of the affected lot. Even if not a warranty issue, their repair rates are very reasonable and I doubt the repair cost would exceed $300. A great deal for a fresh amp. (They check EVERYTHING when doing a repair and reset bias, etc. and replace any questionable parts.)

I finally dug this amp out of the storage corner and opened it up. One of the large caps blew its top. You can see where flame shot out of it. The remaining large caps on that particular board are all slightly bulging. I see no other visibly burnt components.

I sent QSC an email last week asking if they still repair these units since they don't list any parts available for them. Still haven't heard back. If they don't, does any else here repair these or know someone who does?

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