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[John Roberts {JR}]

mel taylor wrote on Sun, 19 November 2006 12:35

For those of you who are concerned w/ (can hear) sound quality, try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's are reliable and big bang for the buck, but the fidelity is just not there.   you get what you pay for. Mel

Most sound professionals knowledgeable about power amps will not be comfortable with your claim that "sound quality" differences are audible in simple listening tests. When listening to a signal chain composed of multiple blocks some of which exhibit much higher levels of nonlinearity, such tests can be compromised by the other weaker links.

You may be able to hear differences in amplifier design philosophy wrt to how they handle; clipping (limiters, PS capacitance, etc), minimum load impedances (current and VI limiting), and even design/manufacturing flaws (excessive crossover or class G-H transition perturbations).

Sound quality, brings to mind characteristics like linearity (THD and IMD), frequency response, and S/N which will be more similar than different between quality professional amplifiers and difficult to parse out in even double blind listening tests (well maybe not noise floor when the music stops).

Perceived differences will more often be caused by simple things like rated or available power. Some designs (like PFC) will be better at extracting power from a given distro so may sound different when pushed hard. There is a place for listening tests to compare how amplifiers act when pushed beyond their rated capabilities, but lets not confuse that with sound quality unless you consider that normal operation.

FWIW amp designers invest a great deal of effort to overload as benignly as possible. Such attention to detail is an aspect of product quality, but more like air bags in a car than a sport handling package (sorry to revert to yet another automotive analogy).

JR

PS: I'm proud I avoided the obvious jokes (viewing art through sun glasses, tasting fine wine in a dirty glass, or that scatological one about judging a fine restaurant meal by.... I'll let you all digest that last one.
 

[Bob Lee (QSC)]

mel taylor wrote on Sun, 19 November 2006 10:35

For those of you who are concerned w/ (can hear) sound quality, try a blind comparison w/ any qsc (or new generation crown) vs. any professional concert amp... lab g, camco, dynacord, etc. no doubt that qsc's are reliable and big bang for the buck, but the fidelity is just not there.   you get what you pay for. Mel

That's funny … the fidelity was there when they left the factory …

[Marty Bilecki]

 
 Did UPS drop the box and the fidelity was damaged in shipping??



Marty B

[Scott Flaws]

No, QSC uses Fex Ex for shipping but if you combined them with UPs  would you have Fed Up??? They might have stole the "hifiness"

[Marty Bilecki]

 
And also funny that my company owns 21 Plx series amps and 6 Rmx 5050's and not one has ever left the rack it was installed in !!!!1

I just got back from service I tech amp number 7 of the 11 I techs I have owned for the last 2 years..

(Reading from the repair invoice in my pocket
" Filter Cap on Usp3t shorted, damage went back to power supply. Replaced Ups3t and input boards , repaired low voltage power supply. Adjusted and tested amplifier to factory specifications. Restored firmware to version 2.048dsp and 2.031Disp. and reloaded customer preset data..")

I must say the turnaround time has been great on all of the amps that have pooped out.. I sent this amp back to Crown on Nov 13 th and it came back today the 20 th..

7 out of 11 of my Hi Fidelity Amps !!!!!!   Cool Eh?

Marty Bilecki

[Marty Bilecki]

  ps   This was an I tech 8000 ..   I was walking around the stage a few weeks back because I smelled something burning...   I thought maybe a tube guitar amp or something...   But it was the stage left house amp rack that was smoking..    Sure enough  ,   One doa I tech 8000....    !!!!

mb

[Adam Kane]

Mel,

Looks like you've got one great set of ears on ya.  From my experience, the only times I've ever been able to hear differences between amps (even with cheapies) was when they were driven into oblivion...something I try hard to prevent by properly sizing the amp to the application and the system for the job.  I believe JR already mentioned something along these lines so I'll go no further.

To the OP,

I can't remember the last time I've had a QSC product fail.  They sound great (unless the fidelity leaks out of the box during shipping) and seem to be bullet-proof.  We sell, install, and use their amps with confidence.  Every time one leaves the shop, we just know that there won't be problems.  I can't think of many (if any) other brands I can say that about.

[mel taylor]

Adam Kane wrote on Mon, 20 November 2006 22:21

Mel, Looks like you've got one great set of ears on ya.  From my experience, the only times I've ever been able to hear differences between amps (even with cheapies) was when they were driven into oblivion...something I try hard to prevent by properly sizing the amp to the application and the system for the job.  I believe JR already mentioned something along these lines so I'll go no further.

mel taylor wrote on Mon, 20 November 2006 14:43

I'm not throwing any products under the bus.  Their amps are good, reliable, lot's o' watts to $s, etc.  Just like other companies, they have their place.  For me, it's just not when you demand the best.

Again, no doubt that qsc is a leader in value and reliability, no argument.
Of course most don't hear the difference, consider "most" of the concerts, or otherwise amplified audio events all of us have heard over the years.  "Most" come with so much distortion and other influencing factors that the fidelity of an amplifier cannot be distinguished by any human.  OTOH, many ears in the business (several I know in Michigan Adam),are always striving for the next level of fidelity.  To my ears, the perfect sound system would not be heard.  I believe with a professional system that's properly optimized, the nuance of sound quality can be distinguished in amplifiers, as well as consoles, etc. Of course the difference may not be realized if the amplifier is not near the weakest link in the signal chain. However, it makes a difference when you get everything as close to perfect as possible.  This is the dramatic difference in "pristine" vs. "good" sound quality that "most" cannot respect, as they've never experienced it.  This is just my opinion, and isn't meant to change anyones mind, but I am part of the audio engineering community, and I have many peers that think likewise. .02

[Bob Lee (QSC)]

You are not alone, Mel. I've heard the same sentiment expressed by guys at Guitar Center and the now-defunct Mars Music, but OTOH I don't think those guys know how to compare power amps.

Have you ever tried a double-blind test?

And I'm serious about the fidelity being in the amps at the factory; the PLX and PowerLight amps in particular would make great studio reference amps if it weren't for their fans. Do you know what went wrong with the ones you tried?

[mel taylor]

Bob Lee (QSC) wrote on Mon, 20 November 2006 23:05

You are not alone, Mel. I've heard the same sentiment expressed by guys at Guitar Center and the now-defunct Mars Music, but OTOH I don't think those guys know how to compare power amps. Have you ever tried a double-blind test? And I'm serious about the fidelity being in the amps at the factory; the PLX and PowerLight amps in particular would make great studio reference amps if it weren't for their fans. Do you know what went wrong with the ones you tried?

Thanks Bob,
I don't shop @ GC, and I'm serious too.  
I am speaking of double-blind tests, many times and places including, outdoors, in a theatre, and more than once in a recording studio.
The PLX are normally, among others, one of the first to go.  
I've nearly never experienced a qsc failure or fault.  One did smoke quickly during 2 Ohm testing - an infant failure.  Rarely, if ever, during an event or install.

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