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Review and Measurements of Crown XLS 1502 Amp

sac

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If that's the case, something is wrong. Take it to be repaired.
lol, now how will this go "whats wrong with the amp sir" ....." a guy on the internet says my fan ought to be absolutely silent, but I can hear it metres away"..........you gotta be kidding.
 
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My XLS is 8 ft from my chair, and I only know the fan is running b/c I can (sometimes) see it start to spin up through the front panel grill!
It's also sitting on top of almost all my other amps & processors....so it does get warmish...still can't hear it, but I assume it's a variable speed fan controlled by a temp sensor circuit, so could have a 'hurricane' mode if really needed.
I wouldn't put one of those on top of a high powered receiver, more out of concern for the receiver than the amp, though.
 
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I have two XLS 2502's on top of five Behringer amps in a closed rack that gets over 125ºf and when I open the rack door I still can't hear the fans. Before the 2502's I had a pair of 1002's in the same spot. I've also used the XLS amps a lot in actual pro environments and have yet to hear the fans.

sac, something is abnormal about your setup, or amps.
 

sac

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"I wouldn't put one of those on top of a high powered receiver, more out of concern for the receiver than the amp, though."

Neither would I, did I mention it was a few centimetres away? Ive since added 4 cm spacers which seems to keep the xls cool enough. to stop the fans triggering Not all of us have unlimited real estate to lay these things out vertically independent from each other and due to its size, the receiver has to go at the bottom of my stack. And yes its a high power receiver, but only providing line level signals , as I mentioned just the idle heat( 35 C on top panel) that rises that is enough to trigger the xls. Infrared measurements of the front panel of the xls, where it seems to get hottest, have the fans triggering in the region of 40 C, what temp on the critical parts inside, no idea.

My equipment is in an open rack, so any noise is not contained by walls of a cabinet etc.

Just putting this out there for folks, its highly unlikely Ive got the only xls that was supplied without the "silent fan", my hearing also is limited now to below 12 kHz , so not superhuman. The noise doesn't concern me enough to think there is something wrong with the unit, just letting people know that claims of it being silent are fanciful and perhaps more indicative of purchaser rose coloured glasses phenomenon.
 
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Sorry, I meant that literally (to myself), not as a put-down to you - I had a high power receiver with a small amp stacked 2" on pads above it, also running as a preamp only, and it still died of heat exhaustion...should have worded that better.

However, my hearing is a bit better than you say of yours (15khz), and the XLS is less than a foot away from the 'front' wall, also open backed, and I cannot hear it at all; but I can hear the fan in the dBX Venu 360, which is tiny, and whines like heck....so not rose colored glasses.
Before I purchased it, I called Crown tech support, and he specifically recommended this over their other Pro amps, partly b/c the fan in this was designed to be quiet enough for home use.
Wonder if the xls fan could be replaced with a Noctua equivalent - I use those elsewhere when I want super-quiet air movement.
I've also had good luck 'quieting' noisy fans simply by blowing/sucking the dust off them....
 

BYRTT

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1) ...I'm using mine only currently to biamp the low end on my speakers, so not going to hear any real effects from higher end harmonic distortion or noise issues...

2) ...I like the ability to able to use the band/crossovers and only send the signal to the drivers that they need, whether this enhances the life of the actual speaker crossovers, don't know.
Its not my business what users like of settings but hope you aware doing 2) in combination with 1) then new EQ filter will cascade to speakers original XO slope and change how intended XO summing region works, so in principle say speakers XO region was optionally voiced ab fabric then any new EQ filtering needs to be global else that optionally engineering work on XO region is detuned.
 

sac

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I
Its not my business what users like of settings but hope you aware doing 2) in combination with 1) then new EQ filter will cascade to speakers original XO slope and change how intended XO summing region works, so in principle say speakers XO region was optionally voiced ab fabric then any new EQ filtering needs to be global else that optionally engineering work on XO region is detuned.
Yes, I sort of understand what you are saying, but if I overlap the crossovers by at least half an octave will it matter?, given that the xls lowpass/high pass rolls off per octave as well? In my case the speaker crossover is at 500 Hz in my two way system, if I set the filter on the xls to 750 Hz to power the low end there will be plenty of overlap there? The top end at present is getting the full range sent to the tweeter..
 

BYRTT

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Yes, I sort of understand what you are saying, but if I overlap the crossovers by at least half an octave will it matter?, given that the xls lowpass/high pass rolls off per octave as well? In my case the speaker crossover is at 500 Hz in my two way system, if I set the filter on the xls to 750 Hz to power the low end there will be plenty of overlap there? The top end at present is getting the full range sent to the tweeter..
: ) as said its not my business if you like 750Hz as what you call plenty of overlap, what i know is if as said XO region was optionally voiced ab fabric that optionally engineering work for XO region will now be assymetric detuned relative to mid/tweeter bandpass and example of visual consequence is plottet below.

Red trace example show a often used 500Hz LR 4th order low pass, looking up manual for XLS amp it say filter is another 4th order LR so blue trace show what you get cascade two LR 4th order filters at 500Hz and 750Hz:
1000.png


In amplitude domain say system was 2 way 4th LR at 500Hz that summed flat on some unknown design axis as blue trace example below then the cascaded 750Hz filter will add the pink trace amplitude difference on same design axis:
1001.png


In time domain on some unknown design axis say filter is textbook for a LR 4th order filter at 500Hz seen in left wavelet graph, then right wavelet show the difference cascade 750Hz filter (dotted line can be read as a group delay graph).
1004.png
 

sac

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: ) as said its not my business if you like 750Hz as what you call plenty of overlap, what i know is if as said XO region was optionally voiced ab fabric that optionally engineering work for XO region will now be assymetric detuned relative to mid/tweeter bandpass and example of visual consequence is plottet below.

Red trace example show a often used 500Hz LR 4th order low pass, looking up manual for XLS amp it say filter is another 4th order LR so blue trace show what you get cascade two LR 4th order filters at 500Hz and 750Hz:
View attachment 26083

In amplitude domain say system was 2 way 4th LR at 500Hz that summed flat on some unknown design axis as blue trace example below then the cascaded 750Hz filter will add the pink trace amplitude difference on same design axis:
View attachment 26084

In time domain on some unknown design axis say filter is textbook for a LR 4th order filter at 500Hz seen in left wavelet graph, then right wavelet show the difference cascade 750Hz filter (dotted line can be read as a group delay graph).
View attachment 26085
Thankyou for taking the trouble to reply and improve my understanding of this issue, yet I don't understand most of what you have posted:

1. XO region was optionally voiced ab fabric ?

2. Bottom graphs, what are they and what do they show?

3. Are you claiming my system would have a 5 dB dip in response at 500 Hz with the xls filter set at 750 Hz?

4. What frequency would the xls setting need to be above 500 Hz to avoid this? or is it impossible.

I do run audyssey on my system, and it returns the same equalisation settings regardless of whether the xls filter is used or not, is that telling me the overlap is enough?
 

BYRTT

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Thankyou for taking the trouble to reply and improve my understanding of this issue, yet I don't understand most of what you have posted:...
Welcome, try understand in examples i use a textbook perfect figure of a 20Hz-20kHz audio domain with a 4th order LR XO point at 500Hz and maybe your speaker ab fabric is not setup to same textbook perfect figure for many reasons, but the value of the difference/distortion graphs that show up as consequence of cascade single filter to only the lowest frq bandpass (assymetric) should be same numbers for actual speaker whatever its XO region looks like in reality.

... 1. XO region was optionally voiced ab fabric ? ...
One can't really know how state of the target/quality/precision was of a probably mass produced speaker build before shipped to customers.

... 2. Bottom graphs, what are they and what do they show? ...
Its time domain graphed as a wavelet in free REW, for info a perfect graph of a 20Hz-20kHz audio band in electric domain will be nearly perfect symetric before and after time zero line but for speaker systems use of filters to sum varius band passes will add phase differences/distortion.

... 3. Are you claiming my system would have a 5 dB dip in response at 500 Hz with the xls filter set at 750 Hz? ...
Yes that's what simulation suggest.

... 4. What frequency would the xls setting need to be above 500 Hz to avoid this? or is it impossible. ...
Sorry as close as possible to same bandwidth as for mid/tweeter bandpass, setting a new filter one should then measure system and and take care implement right filter slopes to the two band passes so they will sum as perfect as possible in amplitude and time domain on acoustic design axis.

... I do run audyssey on my system, and it returns the same equalisation settings regardless of whether the xls filter is used or not, is that telling me the overlap is enough?
Will be guessing here but in consequence of that in real world rooms its very difficult get any meaning full precise acoustic numbers say 500Hz and below, that could be the answer here, that said i have no clue how Audyssey works.
 

EX511

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What would you recommend to power my KEF Q750's using a Denon avr-x3400h or avr-x4400h as a preamp?

All the reviews i've read seem to be powering them with amps in the 250w @ 8 ohms per channel range to get the most out of the Q750's.

I was thinking about going with a 2002 unless you guy's think the 1502 would be plenty

thank you
 
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