Crown XLS 1500 vs. QSC RMX 850

[anonymous101511]

Greetings from the back of the bus. I'm on a 22 show run with Keb Mo and I thought I would do an on- stage comparison between 2 popular cheap power amps. I bought both of them @ $399 each from Gtr Ctr.
I used a Trace Eliott GP11 preamp and a new Mesa PH 2x15" cab loaded with the stock speakers and also with EV 15BX's.
I tested with limiters on and off, in stereo mode and bridge mono into 4 ohms.
The Crown had a pretty clear tone and decent amount of volume before crapping out though the limiter let some distortion still come through. The overall sound was a little compressed but not really bad.
The QSC had a fuller tone with distinctly more bottom end.(still not as clear as my Crest amp:-)) Similar level of perceived volume at full- bore even though 830 watts vs. 1500 claimed watts for the Crown.
The QSC limiter sounded more compressed than the Crown's but didn't allow audible distortion. I liked the sound of the QSC best w/o the limiter. The Crown was best with the limiter enabled as it would distort ugly when pushed that hard. My actual show volume was not quite loud enough to bring about clipping in either case. Small rooms at around 2000-2500 seats.
These results were consistent with both the stock mesa speakers and the EV's ( which sounded better with a clearer tone and full range; also they were more efficient, getting louder at the same amp level)
Overall, the QSC sounds more accurate and the Crown will be going back to the store

[JimmyM]

Bob Lee will be happy to hear that

I'm a little surprised to hear there was an audible difference in the power amps. I keep hearing that power amps all sound the same once they get below a certain THD level that becomes inaudible. Even Bob has said that. But there you go, eh?

BTW, that's pretty refreshing that someone who could get pretty much any new rig they wanted for free is opting to buy a rig

[jnewmark]

Another difference between the two : Crown XLS 1500 = 8.6 lb ,
QSC RMX 850 = 35lbs.

[anonymous101511]

Originally Posted by jnewmark

Another difference between the two : Crown XLS 1500 = 8.6 lb ,
QSC RMX 850 = 35lbs.

yep, and the Crown is silver; the QSC is dark grey.
I really think that the Crown would do just fine as an all purpose PA amp running a pair of full range speakers. You also have the option of using the built- in crossover to run a mono bi-amp set-up. Pretty cool features but sound- wise there are better choices for the same money and that was what I wanted to find out. The sound difference between the 3 amps I used for this comparison was pretty distinct. Band and crew all heard it the same way and as for me, I stayed completely stationary while my tech did the re- patching, probably took 4 or 5 seconds to make the switch. Cheers!

[anonymous101511]

Originally Posted by JimmyM

Bob Lee will be happy to hear that

I'm a little surprised to hear there was an audible difference in the power amps. I keep hearing that power amps all sound the same once they get below a certain THD level that becomes inaudible. Even Bob has said that. But there you go, eh?

If that were the case in practice (not theory) my Bryston amps would sure be overpriced!!

[Bob Lee (QSC)]

I doubt that either amp actually had a fuller tone or more bottom end, unless someone were causing it to do that--in which case the amp would only be passing along a fuller tone or more bottom end without being the cause of either.

The clip limiters in the RMX850 only kick in when the amp channels actually clip. If the clip LED doesn't light, then the limiter's not doing anything.

OP: What does "full bore" mean in your test?

[lo-freq]

Originally Posted by Bob Lee (QSC)

I doubt that either amp actually had a fuller tone or more bottom end, unless someone were causing it to do that--in which case the amp would only be passing along a fuller tone or more bottom end without being the cause of either.

The clip limiters in the RMX850 only kick in when the amp channels actually clip. If the clip LED doesn't light, then the limiter's not doing anything.

OP: What does "full bore" mean in your test?

Is there a sensitivity difference between these two amps?

Also, it would be best to use a recording or looper as your input as very small changes in attack and hand position affect the perceived tone.

[svtb15]

We once talked at the Alleva Coppolo booth at NAMM..

Good post.
We always hear on TB how all power amps sound the same .. I disagree with those people.

However i came to the same conclusion as you did long ago. They DO NOT sound the same at all..

While in NY years ago, I used to run a Crown PSA2 on my rig with a Neve Preamp then later with an Old F2B.
I then went to a BGW750 when the crown was stolen.. They did not sound the same. The Crown won in my opinion...
I also find that the old Crown MA1200 sounds nothing like the newer amps, no matter what anyone says. The MA1200 sounds bigger on a gig IMO.

I am not surprised that you find the QSC to be more of what you like over the XLS...
Ill bet it sounds great. Are you still using your factor basses?

Originally Posted by vail_bass

Greetings from the back of the bus. I'm on a 22 show run with Keb Mo and I thought I would do an on- stage comparison between 2 popular cheap power amps. I bought both of them @ $399 each from Gtr Ctr.
I used a Trace Eliott GP11 preamp and a new Mesa PH 2x15" cab loaded with the stock speakers and also with EV 15BX's.
I tested with limiters on and off, in stereo mode and bridge mono into 4 ohms.
The Crown had a pretty clear tone and decent amount of volume before crapping out though the limiter let some distortion still come through. The overall sound was a little compressed but not really bad.
The QSC had a fuller tone with distinctly more bottom end.(still not as clear as my Crest amp:-)) Similar level of perceived volume at full- bore even though 830 watts vs. 1500 claimed watts for the Crown.
The QSC limiter sounded more compressed than the Crown's but didn't allow audible distortion. I liked the sound of the QSC best w/o the limiter. The Crown was best with the limiter enabled as it would distort ugly when pushed that hard. My actual show volume was not quite loud enough to bring about clipping in either case. Small rooms at around 2000-2500 seats.
These results were consistent with both the stock mesa speakers and the EV's ( which sounded better with a clearer tone and full range; also they were more efficient, getting louder at the same amp level)
Overall, the QSC sounds more accurate and the Crown will be going back to the store

[anonymous101511]

Originally Posted by svtb15

We once talked at the Alleva Coppolo booth at NAMM..

Good post.
We always hear on TB how all power amps sound the same .. I disagree with those people.

However i came to the same conclusion as you did long ago. They DO NOT sound the same at all..

While in NY years ago, I used to run a Crown PSA2 on my rig with a Neve Preamp then later with an Old F2B.
I then went to a BGW750 when the crown was stolen.. They did not sound the same. The Crown won in my opinion...
I also find that the old Crown MA1200 sounds nothing like the newer amps, no matter what anyone says. The MA1200 sounds bigger on a gig IMO.

I am not surprised that you find the QSC to be more of what you like over the XLS...
Ill bet it sounds great. Are you still using your factor basses?

yes, I just brought out the old redburst one for this tour.
Anybody wants to come out and hear for themselves, I'm all for it! I'll even give you passes to the show. :-)

[anonymous101511]

Originally Posted by Bob Lee (QSC)

I doubt that either amp actually had a fuller tone or more bottom end, unless someone were causing it to do that--in which case the amp would only be passing along a fuller tone or more bottom end without being the cause of either.

The clip limiters in the RMX850 only kick in when the amp channels actually clip. If the clip LED doesn't light, then the limiter's not doing anything.

OP: What does "full bore" mean in your test?

Hey Bob, full bore for me means into clipping, clip lights flashing and the sound either being limited or completely distorting.
No variables except for the amp changes, then my tech would vary the volume level accordingly, checking softer settings all the way to completely clipping/ distorting and everything in- between. If someone missed the info, I sat in front of the amp/ speaker combination about 12 feet away and didn't move so comb filtering and such wouldn't be an issue. I played the same bass, the same notes in the same fashion and I can duplicate exactly so that didn't change either. There's a noticeable difference in the sound of the amps at all settings I could hear from 12 feet away, all the way up to how they distort/ clip/ limit. This is intended for people curious about these amps and how they perform in the real world and not the least bit intended as a scientific contention, so please don't feel defensive from an engineering viewpoint.

[svtb15]

Vail. If you get to the DFW Dallas area. Im down with it... if im not out on the road on that day...

Originally Posted by vail_bass

yes, I just brought out the old redburst one for this tour.
Anybody wants to come out and hear for themselves, I'm all for it! I'll even give you passes to the show. :-)

[anonymous101511]

Originally Posted by svtb15

Vail. If you get to the DFW Dallas area. Im down with it... if im not out on the road on that day...

after the first of the year, I think, PM and we'll stay in touch

[svtb15]

Looks like your PM is turned off right now... I will send you my phone number once it s on.. Or if you call Jimmy at Alleva Coppolo ( I think you are friends with him ) he can send it to you too.. if your PM does not work

Originally Posted by vail_bass

after the first of the year, I think, PM and we'll stay in touch

[Bob Lee (QSC)]

Originally Posted by svtb15

We always hear on TB how all power amps sound the same .. I disagree with those people.

However i came to the same conclusion as you did long ago. They DO NOT sound the same at all..

I've not heard anyone claim that all power amps sound the same.

Most power amps don't sound the same. It's not because they're inherently different, but because they're almost always set differently unless someone actually makes the effort to dial them in to match up.

Even two amps of the same model and production run, will sound different if they're just set haphazardly unless by some small chance they happen to get set the same.

Poor-quality power amps will sound different even if their gains are matched because they bend or modify the signal in ways other than simple amplification. OTOH better-quality amps, set up so that they do the same thing, will sound alike.

[JimmyM]

Still nothing booked in Central Fla...GRRRR!!!

[JimmyM]

BTW, sorry if I misquoted you about power amps sounding the same, Bob, but that was the gist I've gotten from you that they would if they were rated for super low THD.

[Bob Lee (QSC)]

Originally Posted by JimmyM

BTW, sorry if I misquoted you about power amps sounding the same, Bob, but that was the gist I've gotten from you that they would if they were rated for super low THD.

If they're good, accurate amps they'll sound alike if you have them do the same thing. If you have them do two different things they'll sound different because they're doing different stuff. Just like if you compare two cameras by shooting, say, a mountain landscape with one and a portrait of a female glamor model with the other, you won't have a good basis for comparison; the results will be vastly different even if the cameras themselves are identical.

[svtb15]

Not you Bob.. But there is an old thread from around here from years ago.. Where folks were saying exactly that (paraphrase) just that... It involved class types etc... IIRC

Originally Posted by Bob Lee (QSC)

I've not heard anyone claim that all power amps sound the same.

Most power amps don't sound the same. It's not because they're inherently different, but because they're almost always set differently unless someone actually makes the effort to dial them in to match up.

Even two amps of the same model and production run, will sound different if they're just set haphazardly unless by some small chance they happen to get set the same.

Poor-quality power amps will sound different even if their gains are matched because they bend or modify the signal in ways other than simple amplification. OTOH better-quality amps, set up so that they do the same thing, will sound alike.

[rpsands]

They all sound pretty much the same to me, unless you're engaging limiting or high pass filters or similar. I've owned a lot and they all feel and sound very similar to the same. PLX, RMX, Drivecore, XTI, DCM. No significant difference. This is assuming the same gain staging and all that.

[svtb15]

ehhh.. The scientists will say one thing. .the weekend warriors that read others opinions on TB say another, then the guys that use them in touring pro rigs and bass rigs will say another. ...
I prefer pay attention to what i experience...