Crown XLS2502 Stereo Amplifier Review

[jedi5diah]

"Both the ADC and DAC therefore sharply limit the bandwidth to 48 kHz. " is this unique to 1502 or entire XLS series?

 

[Alice of Old Vincennes]

I think the price allows for sins to be forgiven. If this amp cost 4k it would get a beheaded panther I guess.

No sins. Just an affordable pro amp.

 

[turbotuff]

ps. someone told me that this Macrotech line was the best Crown. I wonder how Macrotech would compare to current XLS line tested here. I also know from an owner of Macrotech that the fans on it are pretty loud unfortunately.

I would have to agree. Although the 5000 series have variable speed fans that are quiet under normal operation.

 

[DonH56]

"Both the ADC and DAC therefore sharply limit the bandwidth to 48 kHz. " is this unique to 1502 or entire XLS series?

I would guess they use the same front end for the entire series, and perhaps several series, but you might have to ask them to be sure. My hearing does not reach 48 kHz so a don't-care for me.

 

[Matias]

No sins. Just an affordable pro amp.

For the same price range you can get an Hypex NCore NC502MP based amplifier that also has high power ratings but with a lot less distortion.
https://vtvamplifier.com/product/vtv-amplifier-stereo-hypex-nc502mp-ncore-amplifier-500wx2/

 

[Alice of Old Vincennes]

For the same price range you can get an Hypex NCore NC502MP based amplifier that also has high power ratings but with a lot less distortion.
https://vtvamplifier.com/product/vtv-amplifier-stereo-hypex-nc502mp-ncore-amplifier-500wx2/

I fear small shops. Crown been around long time.

 

[Vear]

Heck, you can't get a square wave out of an amplifier of any bandwidth.

Unless I'm misunderstanding the above comment, I disagree. Maybe you can elaborate.

 

[LTig]

Unless I'm misunderstanding the above comment, I disagree. Maybe you can elaborate.

A square wave has infinite bandwidth.

 

[Vear]

A square wave has infinite bandwidth.

True but some amps can produce a perfect square wave at a specific frequency on an oscilloscope that can easily go into the MHz range. So if you see a perfect square wave on an oscilloscope, isn't the amp reproducing a perfect square wave?

 

[LTig]

True but some amps can produce a perfect square wave at a specific frequency on an oscilloscope that can easily go into the MHz range. So if you see a perfect square wave on an oscilloscope, isn't the amp reproducing a perfect square wave?

Sorry, nitpicking here: You cannot create a perfect square wave in the first place, as its bandwidth is infinite. See the Gibbs phenomenon how a bandwidth limited square wave looks like.

 

[Vear]

Sorry, nitpicking here: You cannot create a perfect square wave in the first place, as its bandwidth is infinite. See the Gibbs phenomenon how a bandwidth limited square wave looks like.

No worries, I shouldn't have said "perfect" but @Francis Vaughan just said "square wave".

Would the below 10kHz Square Wave output from an amplifier reasonably qualify as a "square" wave? It looks pretty good to me. I've seen a lot worse at that same frequency and time base.

 

[gene_stl]

An "apparently perfect" square wave still has it's own rise time. Hopefully the generators rise time is ten or one hundred times faster than needed to see if an amp , preamp or other piece of gear can give a rise time ten or twenty times faster than needed for 24khz audio. Perfect square waves only exist in electronics texts and math books. Electronic circuitry will pass a good lookin square wave if its rise time is fast enough to make a sine wave ten to one hundred times the top frequency it needs to pass.

The combination of oscilloscopes and your eyes don't usually resolve such things unless you turn up sweep speeds and gains.

There is also the issue of the flat top. It isn't really flat but it could be very close. I recently saw some manufacturer (I think) published square waves
of a modern reproduction of the venerable Dyna Stereo 70. It had lots of tilt by which you can deduce the low frequency characteristics. The tilt in this case could have been an output transformer limitation or a power supply limitation or both.

There is also data and knowledge to be extracted from the corners. Are they square? Critically damped? Do they ring? Overshoot? and if so how much. To much bandwidth might make stability issues appear.

I am sure it (the Dyna reproduction) sounded great.

 

[Francis Vaughan]

I hope it was clear that by “square wave” I meant a theoretical square wave as I went on to distinguish it from the “as reproduced” signal.
Nothing has zero rise time. Testing amplifiers does require that you are clear about the spectral energy content of your test signals. Whilst it is reasonable to push tests to the design limits and explore behaviour past the limits, there is no value in demanding absurdities. Rather the opposite.

 

[cistercian]

This review is relevant to me since I use a 2502 to drive a pair of JBL SRX835 passive 3 way speakers. (Pro PA speakers)
I wanted to be able to simulate a rock concert at home and I find the pairing up to the task.
The speakers are 95db @ 1watt/meter.
I also found the combo greatly exceeded my expectations...it sounds wonderful to me. I heard new things
in recordings I had listened to for years, which was an unexpected pleasure. I won't claim audiophile nirvana
but my current setup makes me very happy with a wide variety of program material. I think it is excellent!
It also gets ominously loud. The speakers are really nice and I am surprised at how good they are.
Back in the 70's I really liked 3 way speakers...and lots of home set ups used them. Buying these made sense
to me in that regard. Man, they sound great. The 2502 drives them very well indeed.

Modern pro gear is very good...and enough to make me happy. YMMV.

It is worlds better than when I was a teen...amazingly so. Probably good enough and then some for many users.

 

[cistercian]

I should also add that the cost of the amp and speaker combo is excellent compared to "serious"
audiophile equipment. I started down the class D path when my Pioneer SX727 needed caps again
and I decided there was nothing on FM radio anymore that was worth listening to. I bought a XLS 1002
amp to drive my old Bose 301 speakers and was immediately struck by 2 observations.
First, the amp seemed like a wire with gain...it was very neutral. Second, the 301's just could not do the SPL
I wanted.
I could not believe how well the amp performed! Instant conversion for me.
Next I began looking for better speakers. I was disgusted that most makers did not provide response curves
and also did not say much about max SPL. This led me to JBL pro gear and I selected the SRX835 passives and
bought the 2502 to drive them. I am delighted at how my system sounds. Bass notes are ultra controlled and
powerful and mids and highs are fantastic...detailed and transparent.

For full disclosure I attended a concert some time ago and had a chance to listen to the line array in use as
music was played at a normal level before the show. I was amazed at how nice it sounded and noted the array
in use was JBL.

If you want BIG sound, the pro stuff is a bargain. Dynamics at low level listening are exceptional as well.

Class D does not heat the room like class A or AB amps do either and the amps are comically light in weight
for their rated power. The cooling fan is a total non issue. I have only ever heard mine after a non good neighbor
session of extreme SPL when I was finished. At normal listening levels it never turns on. My ears go into compression
long before my system does. As a result I normally listen now at lower volumes and it is fantastic.

Efficient high SPL capable speakers and a powerful amp produces program reproduction so good one is struck
right away by good recordings vs those with poor eq and dynamic range. Mission accomplished and far better
than I thought it would be. No need for a sub either. Room gain is more than enough.

 

[bigx5murf]

I should also add that the cost of the amp and speaker combo is excellent compared to "serious"
audiophile equipment. I started down the class D path when my Pioneer SX727 needed caps again
and I decided there was nothing on FM radio anymore that was worth listening to. I bought a XLS 1002
amp to drive my old Bose 301 speakers and was immediately struck by 2 observations.
First, the amp seemed like a wire with gain...it was very neutral. Second, the 301's just could not do the SPL
I wanted.
I could not believe how well the amp performed! Instant conversion for me.
Next I began looking for better speakers. I was disgusted that most makers did not provide response curves
and also did not say much about max SPL. This led me to JBL pro gear and I selected the SRX835 passives and
bought the 2502 to drive them. I am delighted at how my system sounds. Bass notes are ultra controlled and
powerful and mids and highs are fantastic...detailed and transparent.

For full disclosure I attended a concert some time ago and had a chance to listen to the line array in use as
music was played at a normal level before the show. I was amazed at how nice it sounded and noted the array
in use was JBL.

If you want BIG sound, the pro stuff is a bargain. Dynamics at low level listening are exceptional as well.

Class D does not heat the room like class A or AB amps do either and the amps are comically light in weight
for their rated power. The cooling fan is a total non issue. I have only ever heard mine after a non good neighbor
session of extreme SPL when I was finished. At normal listening levels it never turns on. My ears go into compression
long before my system does. As a result I normally listen now at lower volumes and it is fantastic.

Efficient high SPL capable speakers and a powerful amp produces program reproduction so good one is struck
right away by good recordings vs those with poor eq and dynamic range. Mission accomplished and far better
than I thought it would be. No need for a sub either. Room gain is more than enough.

I'm surprised you found the bose 301 lacking in SPL. I own the 901 from that series, and IME, they've got nearly unlimited power handling, could easily be used as pro speakers.

 

[cistercian]

I'm surprised you found the bose 301 lacking in SPL. I own the 901 from that series, and IME, they've got nearly unlimited power handling, could easily be used as pro speakers.

I found bass extension and HF extension poor. It was easy to drive them into distortion. They are ok as far as it goes
but the small cabinet and bass driver size is a big limitation. They are great for limited space and don't suck at all.
But the titanium dome compression horn in the JBL is far better and the giant cabinet, porting, and 15" LF driver satisfy
bass extension. The mid range in the JBL is based on line array driver technique as well. The JBL speaker is in a very different
category with peak SPL listed in the spec sheet as 137db and elsewhere as 130db.
And 124db continuous. Much louder than the bose 301. And it can do it all day long.
JBL says 800 watts continuous, 1600 watts program, and 3200watts peak. Ominous for home use.
The Bose are good from 10 to 150 watts...and without horns for HF and MF just cannot get as loud.
I almost destroyed the 301's with the 1002 amp. I think they are rated at a peak of 150 watts based on how they
folded under high power. It certainly is not a judgement against them...they are for home use, not sound reinforcement
or PA duty.

I just wanted more.

 

[GeorgeBynum]

Nothing has zero rise time.

Nothing REAL has zero rise time. Back in university days (50 years ago), we used the unit step function for analysis ... zero width, infinite height, area of 1 "time-level".

I cannot even say Laplace any more.

 

[cistercian]

This is a review and detailed measurements of the Crown XLS2502 DriveCore (switching) 2-channel amplifier. It is on kind loan from a member. The XLS 2502 cost US $645 including free shipping from Amazon. It has DSP functionality which I did not test. And is specified to drive 2 ohm load.

From the outside, the XLS2502 is built like a tank:

View attachment 44008​

It is very light of course due to switching topology for the amplifier and power supply. But also very sturdy with plenty of steel to keep its shape.

The two gain controls are notched which gives them a nice feeling but the gain is not matched and is hard to get there using those notches.

Here is the back connectivity:
View attachment 44009

There is a fan as you see but in normal testing it never came up. During stress testing, it did come on but was pretty quiet compared to what I expected. Mind you, I don't think you want it close to you if it is going to be running.

Alas, the fan was insufficient to keep the unit cool under full power. The red thermal indicators came up even though the fan was running. The amp seemed to be functioning still but to be on the safe side, I terminated my testing there. In typical home use, even for subwoofer duty, I doubt that this is a concern as you will see later as far as what wattage we are talking about.

Overall, the impression of the amplifier is positive, making you think you have something made to be run over by a car and still function reliably.

Amplifier Audio Measurements
As usual we start with our dashboard of 1 kHz tone into 4 ohm load at 5 watts:
View attachment 44010

I set the gain to 29 dB for consistency. I also tested it at 19 dB gain and it only made 1 to 2 dB improvement. The reason is that SINAD (signal relative to noise+distortion) is dominated by harmonic distortion. Here, those harmonics are very high order which perceptually is not very good as they are not masked as easily. Anyway, with a SINAD of 71 dB, we have below average performance:

View attachment 44011

The XLS1502 did a bit better in this regard, garnering a SINAD of 77 dB.

Frequency response shows the same sharp cut off:
View attachment 44012

I don't know if this can be changed using DSP programming or not.

Above is with resistive load. Switching to a simulation of a 2-way speaker gets us little difference:
View attachment 44014

So there is some speaker dependency but I would not lose sleep over it.

Crosstalk is OK but could be better:
View attachment 44015

The red line is a $30 amplifier by the way.

32-tone test signal simulating "music" gives a more hopeful picture of distortion:

View attachment 44016

The spray of harmonics is high in frequency where our hearing threshold is higher.

Signal to noise ratio is poor at 5 watts but gets better at full power:

View attachment 44017

Lower gain settings may improve this a few dBs.

Amplifier Power Measurements
You don't buy this amplifier to listen at 5 watts so let's see what it can do when its wings are given enough room to fly:

View attachment 44018

Wow! Nearly 500 watts of power is delivered into both channels simultaneously. The good news doesn't end there. Check out these ratings when distortion is relaxed to 1%:
View attachment 44019

1600 watts of peak power is delivered out of standard 120 volt outlet! These thing is a powerful beast.

Noise level is decent but I wanted to make sure the high gain was not impacting it. So I reduced gain to 19 dB which required some 6 volts of input to drive to clipping:
View attachment 44021

There is no difference at all.

For the rest of these tests I stayed at 19 dB gain. Here is the power output with 8 ohm:

View attachment 44020

Over 300 watts at what should be inaudible distortion for most people.

Finally we get to my stress test. I played with the settings because the high frequency noise shaping would not let me perform the sweep. So I decided to change this test and set the limit to 22.4 kHz (instead of usual 90 kHz) and limit the sweep to 6 kHz. That way, the third harmonic of 6 kHz (18 kHz) is still included in the computation. No music has full power at high frequencies anyway so I don't think we need to keep measuring to 20 kHz with respect to power. Here is the output:

View attachment 44023

As noted, the red warning lights came on as the sweep was going from right to left so I terminated the test. Delivered output was about 520 watts which is still plenty but is naturally lower than 1 kHz which was in high 600s.

Conclusions
These pro amps have mastered the technique of delivering tons of power with distortion and noise kept under control. Lack of power is the #1 reason an amplifier can sound bad. Don't care how good the SINAD is at 5 watt. If you run out of power, you will hear distortion, lack of dynamics, etc. So if you need the power, it is best to get it than to have less of it. And on that front, the Crown XLS 2502 delivers tons of it, breaking all previous records for any amplifier I have tested. The price is ridiculously low for the amount of power you get as well.

Ideally, you would use more finessed amplifiers above bass frequencies and use the XLS 2502 to drive the subs. But if not, the XLS2502 can deliver good performance.

Overall, I am going to recommend the XLS 2502.

------------
As always, questions, comments, recommendations, etc. are welcome.

It is two minutes to midnight. Getting my panthers to model this late at night is costing me overtime pay at 2X their normal hourly rate. So while my time is free, theirs is not. So please donating generously using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

Thank you Amirm for this review very much. Considering the rather pedestrian S/N I am a bit amazed I enjoy mine so much!
I saw the Purifi D class amp review as well...wow that sucker knocks it out of the park!!!

Maybe Crown will come back in a redesign to make this amp even better. But considering how many like it warts and all,
I doubt it. Dollars/watt ratio is epic with the XLS series. I won't be upgrading.

Thanks again!!!

 

[Tucker26]

Big sound-reinforcement subwoofers used for big venues or outdoor concerts certainly can absorb this power- AND MORE. With the long wavelengths of bass frequencies, the speakers typically are omnidirectional, so perceived loudness will fall off as the SQUARE of the distance. Of course there's also room gain... so many factors....

And pro midbass arrays can handle some big watts, too, as well as some midrange arrays. Big venues / outdoor events need LOADS of power. And you don't want the amps even coming NEAR clipping on peaks,

With the mids and treble, the speaker arrays are typically designed to be directional and so often have distance-loudness relationships that better the inverse-square law.

Remember loudness and power have a logarithmic relationship- to produce DOUBLE the perceived loudness you need TEN TIMES THE POWER, regardless of distance.

Minor quibble. Although the average person does indeed perceive that double loudness requires 10 times the power , this varies considerably from person to person. I have conducted carefully controlled laboratory tests using orchestral music as a source and was surprised by how much. I was also surprised to find that some people are able to judge loudness very accurately on the same orchestral material presented on different days, others not so much. The subjects were mostly acoustical consultants, some with years of experience working with noise control and/or building acoustics.