QSC MX3000a question

AngrySailor

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#1
Hey guys, Sorry it’s not Phase Lineral related but I have a question regarding these amps. I have two powering my low frequency cabinets, both are operating bridged @ 4 ohm for 3200w each. Sound is ok, but channel 2’s clip light comes on both amplifiers seemingly before max output? I have momentarily driven them hard enough that channel 2’s clip light is solid then channel 1’s Clip light will light. Channel 2’s gains are down, both amps fed signal to channel 1 from my active crossover. Only channel 1’s signal light is lit as would seem normal. (Actually channel 2’s occasionally light real dim) This seems wrong but I can’t find any information. Any ideas?
 

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WOPL Sniffer

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#2
So what kind of speakers can handle 3200 Watts and not explode from a clipped (read distorted) signal??? I want a pair. Maybe it's time for a recap and some fresh outputs if it's "Running Out Of Gas" How old is the amps(s)?
 

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Also, in bridged mode you have to follow how the manual tells you to set it up. CH2 all the way UP. Then to set the level using CH1. Does that sound about right?? Is that how you are set up? How is your preamp? Is it possible IT may have noise issues? How old it it? It would seem that by the time you get to 3 or 3 thousand watts your windows should have already blown out.... Hell, my windows rattle at a couple hundred with my WOPL and Cornscalas.
 

AngrySailor

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Also, in bridged mode you have to follow how the manual tells you to set it up. CH2 all the way UP. Then to set the level using CH1. Does that sound about right?? Is that how you are set up? How is your preamp? Is it possible IT may have noise issues? How old it it? It would seem that by the time you get to 3 or 3 thousand watts your windows should have already blown out.... Hell, my windows rattle at a couple hundred with my WOPL and Cornscalas.
Darn it! You got it. I grabbed the wrong manual. MXa series DO operate as you describe with channel 2 gain all the way up which is different from my other QSC amps. I’ll try that this afternoon.

For speakers I’m driving 4 Eminence Definimax 4015LF drivers,1200w RMS, 2400w program each with Two per cabinet one amp per cabinet. System operates well with very little noise with no input. I’m using QSC USA 900 for high frequency right now (in stereo) but plan to bridge this and add a QSC 1400 series one also bridged so one amp will drive the left and one will drive the right. There’s an active crossover sending 120hz and below to the big amps, 120hz and up to the stereo cabinets. I’m using a Rotel RA-1412 for its preamp section only.
 
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WOPL Sniffer

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When all else fails, RTFD.... I never heard of QSC before so I went and read the manual. Glad we got you going. :)
 

AngrySailor

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HAHAHA! “Issues” is one way to describe it! It’s a fairly large space this system is in, it also got waaayyyy out of hand... I started with a PL 400 and my dads Sansui AU-7900. Then moved away from home. He kept the Sansui and I didn’t want to keep using the PL in the shop so I scored a couple QSC’s from bars that shut down. The PL is waiting to be hooked up in the house to a pair of vintage Sansui speakers I pulled from a dumpster in near mint condition. Then just recently I found the other MX3000 pretty cheap and bought it mostly for headroom. I could light the clip lights on one pretty easy and still under the speakers powerhandling capabilities. (One mx3000 could put 1200w to each cabinet)

So now with both amps working normally, you may ask “how much louder is 6400 Watts compared to 2400?” Simple. NOT MUCH but I can play at the same max level with no clip lights blinking! There is maybe a tad more available but so far the windows stayed in!
 

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Bradrock

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#11
Wow, what a cool shop! That's a pretty big hit & miss engine in front of the sofa. 15-20hp?
 

AngrySailor

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Wow, what a cool shop! That's a pretty big hit & miss engine in front of the sofa. 15-20hp?
That is a 4hp International Harvester “Famous” model. Roughly 1911 production, big for its power isn’t it! It was seized up bad, I’ve just got the piston removed and looking into installing a liner to repair the bore.

Lee! It’s good to be back! I’ve been in the shadows here and there but been super busy with the mechanical projects and the stereo has been humming along! Only had to recone a few speakers:oops:
 

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Actually mr sailor...... Nothing here on this site is Phase Lineral related


Hey guys, Sorry it’s not Phase Lineral related but I have a question regarding these amps.


:D hahhahahahahahah I made a funny
 

AngrySailor

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New problem that will probably be more electronically in-depth. The USA 900 is running hot even at idle. This started recently and while the amp was in stereo mode driving left and right high frequency. Possibly a bias issue? Think we can walk through a repair or should I send it to my “guy”?

Other high frequency amp arrived today, now have potentially 7400w available into current loadso_O

I am going to hook the series one up stereo and remove the USA 900 until repaired. It’s not right...
 

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