Comparisons between Crest and QSC

[fdeck]

You can count me in Camp A.

Regardless of whether the louder amp sounds better or worse than the quieter one, it sounds different. If one amp is louder than the other, volume is likely to be the major audible difference, and even probably the only audible difference.

Occam's Razor says to eliminate obvious major effects before looking for subtle ones. Power amp design has been refined to the point where the two major effects are overall volume and personal bias. Those effects are removed by the double-blind test. If you don't remove those effects, then a listening test is pointless.

Where does this leave the bass player who doesn't want to set up a bunch of double blind tests? My conclusion is that I would simply skip the listening test altogether.

 

[Lowtonejoe]

There have been several threads comparing the performance of the Crest CA9 and the QSC PLX over the past few months. Aside from experience opinions (which matter a lot), it seems difficult to separate the wheat from the chaff.

1st question: is the difference in performance due to differences in the input sensitivty?

If so, shouldn't we be comparing the performance between the CA9 and a PowerLight which includes an Input Sensitivity adjustment capability?

If not, is it just simply the mass of the output transformers.

I can't tell whether everyone is trying to be diplomatic or just don't know the answer. However, given the weight considerations, this seems like a pretty important issue to get square on (if possible).

I am always amazed when people criticize QSC amps as not having oomph, punch or bottom end.

When I need to play my bass loud, I don't boost the lows on the pre I boost the mids.When it needs to be punchy I modify the attack I apply to the strings and turn the bass on the pre up a little.
For warm, pillowy walls of bass I turn up the bass a little, leave the mids at 12 o'clock and turn down the treble.

My QSC amp performs excellently in all these scenarios.

Last week I bought a Korg Electribe R mkII. This thing does everything from sub tones to kick tones to snare to toms to high hats AND can create synth tones in that entire frequency range.

For kicks I ran it through my rack. ER1-mkII --> RBI --> QSC PLX 2402 running paralell in dual mono out --> one side feeding a 200w Bag End S15-CUS and the other side feeding an Eden D210XLT.

This unit comes with pre-programmed demo songs so I lit this sucker up and started listening at low volume. It sounded pretty good! As I kept messing around with it I kept turning up the volume

Guys, I am surprised no one called the cops. I was getting chest thumpin, pants flapping bass out of my rig. I would NEVER need to play that loud. If I did, noone would be able to hear anything else on stage! And this was not even in Bridged Mono!

QSC amps have balls. Don't doubt it. If you prefer another brand, that's cool. QSC is just one of several fine choices out there. I own a PLX 2402 for my bass rig and I own 2 RMX amps for my p.a. I have had nothing but excellent performance out of these babies and thunderous power whenever I need it.

Joe.

 

[jokerjkny]

It's fine to use your amp gain control to adjust volume. It's just that when you compare them, do it at the same gain. Otherwise, the lower gain one will tend to sound thinner with a given input level, even they are exactly the same amp.

This is a psychoacoustic phenomenon that's been known for decades, except in many parts of the music world. See [Invalid or Expired Link Removed]below.

pictures are pretty.

and i'd just go w/ whatever PLX is being price freaked at your local instrument super mall. just got a PLX3002 for about $0.23 / watt!

 

[Horny Toad]

I am always amazed when people criticize QSC amps as not having oomph, punch or bottom end.

Joe, have you ever compared your QSC's to other brands? I owned a 2402 and 3402 and was very happy with their performance. Mostly out of curiousity, I purchased a Crest CA9. I have since sold both PLX's. Don't misunderstand me, this isn't a criticism of QSC amps at all. They are loaded with features, powerful, very lightweight, extremely reliable. I honestly can't say one negative thing about them. Once I tried the Crest, there was no going back for me.

So what's the point of all this? Try different equipment, take into consideration all factors such as features, price, weight, etc. and above all - trust your ears. For me, I don't care "why" something sounds better to me. If something sounds better (to me), then that's what I'm going with.



Link Removed

 

[pickles]

Occam's Razor says to eliminate obvious major effects before looking for subtle ones.

I don't mean to be argumentative, but IMHO that is not a correct use of the principle.

Occam's Razor says:

"one should not increase, beyond what is necessary, the number of entities required to explain anything."

or

"Given two equally predictive theories, choose the simpler, and The simplest answer is usually the correct answer."

Which doesn't really seem to apply here, but if we wanted to apply it in this case I would interpret it to mean that we should not assume any part in the system is "perfect", the simple answer is that each device will change the sound.

What you are describing is the principle of "pick the low hanging fruit".

 

[pickles]

Joe, have you ever compared your QSC's to other brands? I owned a 2402 and 3402 and was very happy with their performance. Mostly out of curiousity, I purchased a Crest CA9. I have since sold both PLX's. Don't misunderstand me, this isn't a criticism of QSC amps at all. They are loaded with features, powerful, very lightweight, extremely reliable. I honestly can't say one negative thing about them. Once I tried the Crest, there was no going back for me.

So what's the point of all this? Try different equipment, take into consideration all factors such as features, price, weight, etc. and above all - trust your ears. For me, I don't care "why" something sounds better to me. If something sounds better (to me), then that's what I'm going with.



Link Removed

+1.

I'll post my whole GAS story on another thread after a couple more field tests, but it sure looks like a blew a couple thousand bucks on cabs and preamps when what I really needed was a CA9.

 

[bugbass]

One man's thin is another man's tight.

Very true

 

[Bob Lee (QSC)]

Which doesn't really seem to apply here, but if we wanted to apply it in this case I would interpret it to mean that we should not assume any part in the system is "perfect", the simple answer is that each device will change the sound.

No, you are incorrectly applying the principle by making an a priori assumption. fdeck applies it correctly. In a race to determine whether A or B was faster, you would have a start line and a finish line and either have both start at the same time or clock them. This may seem more complex--less simple--than to just let A or B start and arrive randomly, but for the purposes of determining which is faster, it is simpler because it reduces--shaves away--the unnecessary variables. Structure does not necessarily mean less simple.

 

[Bob Lee (QSC)]

trust your ears

Here are your ears:

Know what they're doing, then trust them. That's why there are double-blind tests.

 

[Horny Toad]

Here are your ears:

Know what they're doing, then trust them. That's why there are double-blind tests.

No thanks. I'll trust them without the chart.



As a matter of fact, I'll take the advice found in your signature...

"If it sounds good, it is good."
-Duke Ellington



Link Removed

 

[Bob Lee (QSC)]

No thanks. I'll trust them without the chart.

Is the chart wrong?

 

[Mark Reccord]

I don't have an iron in this fire, but how many of you have actually made the effort to properly match gains when auditioning power amplifiers?

If you still hear a difference with gains matched, fair enough, but without doing that in an audition, there's absolutely no grounds to say amp X sounds better than amp Y, because the playing field is not level. Anyone who makes a choice between power amps without matching gains is not making an informed decision.

I do hear differences in power amps with gains matched, BTW, but they're pretty subtle until you get towards the linear limits of the amps.

EDIT: Trusting your ears is all well and good, but it's useless if the other variables aren't fixed.

 

[Horny Toad]

Is the chart wrong?

I don't question the chart, but it is meaningless to me. You're the engineer, so I trust your facts and figures. It's just that they don't mesh with what I've experienced. The reasons for that are irrelevant to me. Might matter to some, but not me. Different strokes, that's all......



Link Removed

 

[Horny Toad]

Trusting your ears is all well and good, but it's useless if the other variables aren't fixed.

Useless to who? You, I'm assuming. I've owned and used both brands. I liked one brand more than the other. No need for me to match gains, conduct double-blind tests, etc. I simply tried different equipment and made a choice based on what pleased me more. Pretty simple stuff. Not useless to me.

But hey, it's what makes the world go around. It's all good.




Link Removed

 

[WovenGraphite]

IMO the PLX sounds rather thin comparing to the CA9. The CA9 is a monster with headroom to spare

Come on... once the drummer starts to bang and the guitarist starts to rattle does it really make a difference?
I am using a PLX and did so for the weight (old age)

 

[WovenGraphite]

Link Removed

Man THAT is disturbing... could you just add a tad bit more to that video... I want to see her face

 

[bucephylus]

Perhaps, I understand just enough of this to post something stupid and confuse things, but here goes:

Bob's plot shows the intrinsic bias of an average human ear. That's fine, but it does not indicate how we perceive tone.

In practice, the output of the amplifier is measured as a function of frequency. This makes the various amplifiers all look pretty similar presuming they are properly engineered.

However, I don't have a good feel for how transients get measured and characterized. Showing two different frequency response spectrums that look simliar does not tell the whole story. We experience tone as a dynamic response. I can easily see how different output devices interacting with different dynamic loads could produce distinctly different experiences. And, just setting gain level to be equal could still lead to different perceptions.

All this said, I don't have any problem with the tone out of the QSC I've been using for a bunch of years now. I think it's a pretty great unit. OTOH, if some have different opinions based on experience, that is also interesting. And isn't that one of the points of this forum?

 

[Bob Lee (QSC)]

I don't question the chart, but it is meaningless to me. You're the engineer, so I trust your facts and figures. It's just that they don't mesh with what I've experienced. The reasons for that are irrelevant to me. Might matter to some, but not me. Different strokes, that's all......

I'm not saying you need to do anything. You can choose an amp based on its color, its knob feel, the sound of its name, whatever, and attribute the choice to its sound, because even amps that perform identically will sound different at different volumes. That's the fudge factor in sighted tests.

I'm not saying the CA9 isn't a great amp. It's very good and accurate at putting out just a bigger version what you put into it, without altering the signal in any more-than-infinitesimal way. The PLX amps are also, as are good, competently designed amps of other brands.

That's why people who actually take double-blind listening tests with gains matched are often astounded to find that they have real difficulty telling one good power amp from another based on sound alone, especially when they start out thinking one will sound noticeably different from the other.

 

[Horny Toad]

Man THAT is disturbing... could you just add a tad bit more to that video... I want to see her face

Alizee's lovely face....


Link Removed

 

[Horny Toad]

......people who actually take double-blind listening tests with gains matched are often astounded to find that they have real difficulty telling one good power amp from another based on sound alone, especially when they start out thinking one will sound noticeably different from the other.

Bob, I don't doubt you for a second. Just not interested in taking a double-blind test to help me figure out what it is that I like, or why I like it.



Link Removed