Post by SotRPost by Arny KruegerPost by SotRThere is a QSC GX5 power amp for sale near me.
I see they are manufactured in China so that is of concern.
That concern will put you out of much of the pro market these days.
Post by SotRBut I followed a thread between a QSC exec and an inquirer. The exec was
adamant about QSC's close scrutiny of quality control.
Left to their own, Chinese QC can be variable. Under close supervision, it
can be very good.
Post by SotRAny personal thoughts about these amps?
No experience. My old QSC amps soldier on, but they were from a different
time and place.
Post by SotRWill be used for 4 piece '70's to current hard rock bar/club/party band.
Nothing unusual, I see.
Your bigger concern should be the sample of the amp itself, if it is used
equipment.
I've bought used amps that seemed to work fine, but performed well below
specs and new equipment actual performance on the bench, and in real world
use when stressed. Most large power amps use a number of output devices in
parallel, and if some devices or their assoicated components fail to be open
circuits, the symptom is that the seems to work well enough when stressed
lightly, but the amp is down on power, particularly into low impedance
loads.
Post by SotROne other question is the RMS output. I can only find "Program" rating
which I assume means about the same thing as Peak Power.
http://qscaudio.com.s3.amazonaws.com/downloads/specifications/GX_spec...
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Yes I did already see the QSC spec sheet but I can't find where is
specifically states RMS output. I did see a spec 550watts---900watts
it would be fine for us. We are currently using a 300x2 power amp for
rehearsal which we then use for our monitor system at gigs and rent a
main mixer. But we just picked up a nice little Peavey 10 ch. mixer so
another power amp for the main and we're set.
The seller of the QSC says (the proverbial "used once") that it is
like new, in the box. He has a ton of stuff listed seperately. Not
sure why he is selling out but he has a large sound system with a
Mackie mixer, JBL tower mains, rack equipment etc etc. Looks sorta
like he bought this mondo rig thinking he was going to be a soundman
and for whatever reason is bailing out. Have not talked to him yet
because I wanted some expert opinion to go on first.
Thanks for the input everyone
SotR
Look at the second page of the sheet Arny linked to. It states the
power output using a 1kHz sine wave test tone. That is the continuous
power output capability before clip. "rms" and continuous power rating
are often used interchangeably with power amp output specs. It might
be a bit less using 20-20kHz sweeps, but not too far off. Most amps
can't put out their 1kHz rating at very low frequencies into reactive
speaker loads. Depending on the amp, it may be a fraction of the rated
power into dummy load due to the output voltage vs. current phase
alignment.
Very generally speaking, the program rating of the speakers being used
should be somewhere around that continuous (rms) amp power output
rating. If you play heavily compressed music or music with a lot of
high energy sine wave content at full power, it's recommended that you
size the amp closer to the rms rating of the speakers rather than the
program rating to avoid exceeding the rms specs on the speakers and
cooking the drivers. If you clip and amp, it can put out up to 2x it's
continuous/rms rating. So you have to be careful to never clip the
amps when you're pushing them with highly compressed sources. For most
live sound applications, matching continuous output of the amp to the
program rating of the speakers works fine - even more so if you have a
good processor with both rms and peak power limiting capability.