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Author Topic: Epected life of a QSC DCA1644 Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-07-2015 01:26 PM                     I have never retired ANY QSC amplifier for that matter. Not even a USA Series amp. I just rebuild them to like new again. Cost to rebuild one is about 1/4 the price of a new amplifier. I have had theaters remove them and install newer QSC amplifiers. The old ones eventually find new homes. At some point even in the DCA you are going to have to replace power supply capacitors. This is true of just about all amplifiers out there. IMHO... if an amplifier hits the 20 year old mark then think about recapping it to maintain best performance. Caps age and they dry out and become leaky and so on. Also, caps age faster in hot running amplifiers, so keep that in mind. Mark  |  IP: Logged Steven Smith Film Handler Posts: 35 From: Boyce, La/ USA Registered: Jul 2014 posted 01-07-2015 02:30 PM                     Thanks for the input. Mine won't get driven very hard at all and I'm even thinking of running a small air supply into the AVR closet to spoil the equipment, but I guess nothing can fight age and like you mentioned caps drying out. Are there any references on how to troubleshoot these amps? I know basic electronics like testing caps, resistors, diodes, inductors and have the test equipment (LCR meter etc) but usually I know it's highly recommended to take the component out of the system to test it. The only reason I ask is sometimes I see some "not working" DCA amps for sale. Wouldn't mind having another one of these to run some surrounds and rears.  |  IP: Logged Bob Healey Film Handler Posts: 93 From: Milford, CT Registered: Sep 2001 posted 01-07-2015 06:32 PM                     If you do play with forced air ventilation, the QSC amps take in from the rear and exhaust via the front, while the Crowns take in via the front and exhaust via the rear. I'm not a fan of the new Crown amps myself, but I've never had one of their old Macro-techs fail on me. Just swapped a set of MA-1200s in for a set of failing 20 year old Ashly FTX units. They're on semi-permanent loan until something gets done about the Ashlys. The Crowns survived 20 years of concert/event duty. A thing to remember with Crown is they were originally signal, not audio amplifiers, so they had none of the protections you would want for speakers, such as DC filters on the outputs. A story I've been told is back in the '80s, the power supply for a mixing console failed. It wanted +/- 15VDC, so the audio crew took a Crown D-150, hooked a D Cell battery to its inputs, bridged it so it made +/- 15V and they ran the show off of that for the night, with minor tweaks to the attenuators as the D cell started to drain.  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-07-2015 07:02 PM                     Crown amps suck and have always sucked. I have a Macrotech 600 with blown outputs on the bench as I type this. I will post pictures tomorrow and explain why Crown amps suck. Mark  |  IP: Logged Dave Macaulay Film God Posts: 2321 From: Toronto, Canada Registered: Apr 2001 posted 01-07-2015 09:12 PM                     Crown amps have been good and bad for me. If they get past the first few weeks without blowing out, they seem to last a good long time. I have lots of older QSC amps with issues, the early MX series had insufficient airflow (later ones had more powerful fans) and cooked their boards when worked hard for example. No affordable amp will deliver rated power output indefinitely but the MX and USA series come up seriously short for sustained output power capability (in my opinion): yes, they do deliver rated output but shut down for overtemp within a minute or two at max thermal load. The DCA class D amps are much better at this. The big problems come when bargain hunting owners install impressive looking amps with a big chassis full of nothing but air - hello Pyramid - that crap out when asked to deliver some reasonable fraction of their "rated" power output. Nice meters, though!  |  IP: Logged Mark Gulbrandsen Resident Trollmaster Posts: 16657 From: Music City Registered: Jun 99 posted 01-08-2015 01:06 PM                     I also hate using amplifiers that blow their hot air into the rack!! The racks need to stay as cool as possible for long equipment life. Mark  |  IP: Logged Stephan Shelley Jedi Master Film Handler Posts: 854 From: castro valley, CA, usa Registered: Nov 2014 posted 01-08-2015 01:31 PM                     Ashly can repair FET and FXT series 3 no problem and at a reasonable cost. You can remove the amp model for each channel separately. They just plug in. That way you do not have to ship the very heavy amp. Just the much lighter module. FXT series 2 can be much more of a problem. If the PC board is burned it is toast as Ashly does not have any more boards. If it is components they can fix. I have had them rebuild 2 FET modules and recondition an input board for around $180.00 that included return shipping. I agree with others on here that the QSC DCA amps are rock solid. Older QSC can also be repaired at reasonable cost but they do go out from time to time.  |  IP: Logged

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