Do I want a QSC MX1500a Power Amp?

[tlite]

I have the chance to get one or two of these for free from an old movie theater.

https://www.qsc.com/resource-files/...nued/mxa/mx_1500a/q_amp_mxa_mx1500a_sepcs.pdf

Just looking to add some dynamic range to my current setup. I currently have two integrated AVR's. A vintage Marantz 2235 (35 WPC), and a ten year old Onkyo TX-NR808 (135W RMS).

My mains are Triangle BR08 floorstanders (92dB sensitivity, 8 ohm but dips as low as 3 ohms), with a BRC1 center channel (90 dB sensitivity, 8 ohms, dips to 5.3 ohms). When using for 5.1 home theater setup through the Onkyo).

Would the driving the left and right mains with the QSC sound better here or just add clutter to my AV cabinet?

 

[stillspin'n]

I think the QSC's sound great, really come to life with a good preamp and more than enough power. If there free, I say try them out, what do you have to loose.

 

[tlite]

I think the QSC's sound great, really come to life with a good preamp and more than enough power. If there free, I say try them out, what do you have to loose.

Cool. Thanks. Yeah just didn’t know anything about these and if it was worth messing with. Only thing I have to lose is an afternoon with my family annoyed that I have the home theater torn apart. Again.

 

[coonmanx]

Go get some Cerwin Vegas, hook it all up outside and throw a block party. Or maybe use some Klipsch. LOL. Looks like plenty of power.

 

[vinyldavid]

They sound pretty good for big pro power, but the fans are real loud. Best used if you have an amp rack located in a separate room. I have an MX2000A I got from my high school a decade ago that I'm still deciding on.

 

[bowtie427ss]

Best used if you have an amp rack located in a separate room.

This would be true of any 30 year old power amp with fans that were clapped out 20 years ago. They(fans) all make noise a decade or two past worn out and stuck in high speed, Marantz and McIntosh included. The informed will replace them with ball bearing units that won't make noise again in their lifetime

QSC made a lot of amplifiers that sound worse than the MX series, most in fact.

 

[cmjohnson]

I know this is a 3+ year old dead thread but I know these amps quite well.. They MUST be recapped every decade or so or they'll die and burn the PC board. Less often if you don't use them much, definitely every 10 years if they're in heavy usage. That is the preventative maintenance they need, plus occcasional cleaning and checking the condition of the cooling fans every so often. At this point assume they can use new fans.

When they fail, the failures are caps, power transistors, (easy ohmmeter checks for shorted ones is all you need), and the bilevel hybrids are what generally needs changing out. The hybrids are no longer available from QSC so you have to salvage them from donor amps. Unless you WANT to troubleshoot surface mounted devices on the hybrids.

They don't give up much sound quality at all even when compared to some very high end, ultra expensive amps. I run them in my own music system, and my system is definitely well into serious audiophile territory. I use a pair of MX1500As to drive a biamped pair of Aerial Acoustics 10Ts, four channels of amplification to drive the 10Ts in biamp mode.
This gives me a legit 1000 watts RMS into 4 ohms. And I've heard EVERY watt. Driven them until clipping LEDs began to flash a little. Sounds HUGE.

I keep at least one spare MX1500A ready to go not because I expect mine to fail, but because I want a spare to test other speakers with.

I mod all of mine. I get WBT RCA binding posts, XLR jacks, and Speakon connectors and add all these input and output options to the back panel. Fortunately the chassis already has conveniently placed holes for adding Speakons for both channels AND a center Speakon for bridged mono mode.

 

[GordonW]

I can't definitively remember the differences- but IME, the original MX1500 seemed to be quite a bit more long-lived and reliable than the MX1500A. I do have a vague recollection, though, that the original MX1500 did not have the problematic surface-mount components.

I've seen quite a few MX1500As that were burnt beyond reasonable repair- but that almost never seems to happen to the original MX1500.

IMHO, if I was going to use a vintage pro amp of this kind of power for home use- I'd probably go looking for something like a Urei/JBL 6290, instead. To my ears, it sounds even better, and it's pretty much bulletproof. Yes, it is huge and titanically heavy (63lbs!), but if you're just hooking it up in a home and never moving it- that's not too much of a problem...

Regards,
Gordon.

 

[cmjohnson]

As I remember, the 1500 has separate but identical circuit boards for each channel. The A model uses one board for both.

So arguably, the 1500 is more serviceable, and repairable to this day. But I have only dealt with the newer A models.

 

[soundmig]

Love the MX-1500 & Mx-1500a amps. If they are working properly, they sound fantastic!!! But they are now getting to be pretty old, so even if you find one, its likely due for some bench time. Worth the effort though