Crown XLS2502 Stereo Amplifier Review

[audioBliss]

Basically the only reason to used sealed subs is because you want to reach as low as the room allows. In my current room it's 7Hz before drop off. But as you might know sealed subs naturally roll off at 40Hz or whatever so they need to be boosted below that. Typically you might need to boost about 10dB to get it to above a flat line. Every 3dB costs twice the power. So if I have to boost 1.5dB just to get flat response from the amp it's pretty significant imo. But sure the subs probably don't need that much power for really low frequencies or they would break But still I like to remove as many variables as possible in the chain so that I know what is happening when calibrating or whatever. To me at least it seems that it would not be too hard for them to make the amps so good that you can just take them out of the equation so to say. It's hard enough getting excellent sound.

 

[Balle Clorin]

I would recommend everybody listening to a system with high efficiency (90+ dB/watt, ideally 95+) speakers and/or a high-output amp like this, if you ever get the chance.

Once you have heard a system that achieves that, it will change the way you look at audio.

It's not about hitting massive SPL output levels. (Although that's obviously fun too, for brief periods of time)

It's about sounding "effortless" - handling every dynamic peak in your music without audible distortion. Even at moderate listening levels, this is very pleasing to the ear.
...

Yes I agree, I have got 95-96 dB/2.83V speakers, and it has some good benefits, One is that I only need my 30Watt class A to drive my neighbors out of the building, listening is done at 0.1-1watt, And distortion is naturally low. No need for high power amplifier . The problem with high efficiency speakers is they often have a poor(uneven) frequency response even if mine are not bad at all ( http://www.troelsgravesen.dk/JA8008.htm ) I tune the errors mine have + room effects with DSP with success. An example below, I use to slope the frequency response q bit more than shown below....

 

[NTomokawa]

big Cerwin Vega

Would love myself some big CV speakers for surround sound.

 

[Doodski]

Would love myself some big CV speakers for surround sound.

Yeah Those big 18"-21" Cerwin Vega woofers are thumpers. I sold the Cerwin Vega for years and it was reliable, loud and proud >@^_*@< A easy sell it was and a no brainer for parties and rock and roll(pre rap days).

 

[JohnBooty]

Would love myself some big CV speakers for surround sound.

I have their spiritual cousins, the BIC RTR EV-15s. Compression horn, midrange radiator, and 15" woofer. 95dB @ 2.83V/1 watt, 1 meter, 24Hz-20kHz +/- 3dB and by my quick and dirty measurements that seems legit. They look like ghetto blasters, but they don't sound like it... no exaggerated bass, it's a pretty flat response. MSRP is $800/pair but street price is usually more like $400/pair with free shipping to store.

With the grilles on, you don't even have to look at the fugly red woofers. Not my photo... mine are stashed in the garage so the wife doesn't murder me. But they can look somewhat respectable: https://www.dropbox.com/s/e82oejiyerw1zk0/BIC-Eviction-Living-Room.jpg?dl=0

The tweeter is not the last word in surgical audiophile detail, but it is not harsh either. They are pretty tonally correct out of the box and obviously there is an abundance of headroom to play with if one wants to shape the response with EQ/DSP. They easily play louder than needed with my pedestrian HK 3390 amp, and really shine with a high-output amp like the Crown XLS.

Check Google, these things have the beginnings of a small cult following. At $400/pair they are a strong contender for the best bargain in our hobby. 99.9% of audiophiles will turn their noses up at these without a second thought based on price and appearance, but throw in a $100 MiniDSP and some modest amplification and you've got a system with flat smooth response and effectively unlimited headroom down to the 20hz range for maybe $800 all told, perhaps even less. What a time to be alive.

 

[NTomokawa]

fugly red woofers

I love meself come coloured woofer cones. Too many black out there!

Cerwins don't really have a reputation for sound accuracy, though if I build a home theatre setup, accuracy wouldn't be on top of my list... Loudness without distortion would be.

 

[restorer-john]

I'm sorry, this amplifier does nothing to advance the state of the art in high fidelity or for that matter, sound reinforcement. It is just a cheap (and very good value) PA amplifier that delivers a lot of power. Hardly the basis for an audiophile or even an HT system with aspirations to be anything other than just bloody loud (JBL). Basically, the amplifier would be a good choice for a mobile DJ or a backyard barbecue party.

The THD at 5W/4R is dreadful, as is the THD at any power level from mW to full power.
The bandwidth is a joke, surely there's something in the DSP set incorrectly.
The S/N is poor.

@amirm This is an amplifier you're testing, not a DAC. It's up to you to determine if the bandwidth does indeed drop like a stone at 20KHz, not just say:

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

But this statement is the real worry:

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.

If you want your reviews to have any credibility whatsoever when it comes to amplifiers, you must measure the maximum power delivered across the 20Hz-20KHz bandwidth at the manufacturer rated distortion or less. That is the absolute minimum standard.

A 6KHz upper frequency limit for the fundamental just so you can squeeze in a few harmonics before 20KHz to get a number? Another helping hand delivered for Class D I guess.

What happened to the square wave BTW? We were just getting used to it.

 

[JohnBooty]

I love meself come coloured woofer cones. Too many black out there!

Cerwins don't really have a reputation for sound accuracy, though if I build a home theatre setup, accuracy wouldn't be on top of my list... Loudness without distortion would be.

Yeah, I always heard over the years that CVs had a majorly V-shaped response. I wonder if that's still the case. The BICs mostly avoid that, which is why they caught my eye... was shocked to see a mfr claim of +/- 3dB on such an odd specimen.

Although, that's the beauty of these high-output beast speakers in our glorious modern age, even moreso than in the heyday of these monkey coffins 30-40 years. Assuming there's nothing really egregiously wrong (big cancellation nulls at the crossover point, etc) there's a ton of headroom to play around with for DSP corrections. As opposed to running major DSP corrections to a typical bookshelf speaker, where you can wind up with something tonally correct but about as efficient as a soggy potato.

 

[amirm]

If you want your reviews to have any credibility whatsoever when it comes to amplifiers, you must measure the maximum power delivered across the 20Hz-20KHz bandwidth at the manufacturer rated distortion or less. That is the absolute minimum standard.

Why? What is the basis for validity of such a standard? We stick our head in the sand and pretend those guys knew something about real world and see if we can pump 800 watts into a tweeter?

 

[amirm]

What happened to the square wave BTW? We were just getting used to it.

You can't get a 10 kHz square wave with a 20 kHz bandwidth amplifier.

 

[JohnBooty]

Hardly the basis for an audiophile or even an HT system with aspirations to be anything other than just bloody loud (JBL). Basically, the amplifier would be a good choice for a mobile DJ or a backyard barbecue party.

Based on your posts, from which I have learned much in my time on ASR, I think you have more audio wisdom in one of your fingernail clippings than I do in my entire body.

However, I hope perhaps you can hear one of these someday. I think that in real-world usage it would be more enjoyable than what you describe. Again, please understand I am not claiming they obsolete any high-end gear.

(FWIW, I actually did literally buy my Crown XLS for backyard BBQ parties. Were you reading my mind? If so, I'm afraid it was a short read...)

 

[restorer-john]

You can't get a 10 kHz square wave with a 20 kHz bandwidth amplifier.

I know that and you know that. So we give bandwidth limited amplifiers a free disability support exemption pass for square waves do we?

 

[amirm]

I know that and you know that. So we give bandwidth limited amplifiers a free disability support exemption pass for square waves do we?

What would you learn from a sine wave result? That Fourier was right?

 

[Francis Vaughan]

Heck, you can't get a square wave out of an amplifier of any bandwidth. Square waves can be used to elicit bad behaviour out of amplifiers with specific design issues, but they are otherwise useless as a metric of quality.
The square wave as reproduced by the amplifier is exactly defined by the frequency response of that amplifier, and indeed one can be trivially derived from the other. It is a matter of convenience in representation. You would be very hard pressed to visually glean the aurally important information presented in the frequency response from a square wave reproduction, so it makes sense to use the frequency response representation.

 

[March Audio]

I know that and you know that. So we give bandwidth limited amplifiers a free disability support exemption pass for square waves do we?

John, whilst I might agree this amp is not a hifi amp, we have discussed this to death elsewhere.

Square wave reproduction does not equal audible fidelity. With respect you seem a little obsessed by this. It's just a representation of bandwidth.

CD does not not reproduce square waves due to limited bandwidth. Any square wave above 7.4kHz will come out as a sine wave! Its just not relevant.

 

[restorer-john]

Why? What is the basis for validity of such a standard? We stick our head in the sand and pretend those guys knew something about real world and see if we can pump 800 watts into a tweeter?

The audio landscape was, and is again in danger of returning to, a wild west of deceptive practices, specifications and misleading claims. You can choose to either be a shining light for truth or water down hard won standards and lose credibility. Your choice, your site.

You know full well the audible bandwidth (20-20K) is a bare minimum and an amplifier must behave in a linear fashion across that bare minimum bandwidth. And yet you propose to cut it at 6KHz for power testing?

 

[restorer-john]

John, whilst I might agree this amp is not a hifi amp, we have discussed this to death elsewhere.

Square wave reproduction does not equal audible fidelity. With respect you seem a little obsessed by this.

CD does not not reproduce square waves due to limited bandwidth. Its not relevant.

Alan, it's the proposal to do power vs THD testing and stop it at 6KHz. which I find dreadful. Read my entire post, not just the last throwaway line.

The square wave mentioning was merely illustrative of Amir's narrative changing depending on the topology of the amplifier he tests. Consistency is key.

 

[March Audio]

Alan, it's the proposal to do power vs THD testing and stop it at 6KHz. which I find dreadful. Read my post.

The square wave mentioning was merely illustrative of Amir's narrative changing depending on the topology of the amplifier he tests. Consistency is key.

Well it is necessary to state why the narrative changes, but testing should be relevant to the device. This amp has an A to D on the front end which is steeply filtered.

I'm interested in distortion you can hear, not low level harmonics at 40, 60, 80kHz etc which are not audible, or reproduced by your speaker even if they were.

Can you explain to me what's the point of testing (in this publication - consider the wider audience) for a condition that will never exist in the real world? You will never see full power at 20kHz, not even vaguely close to it, so can you explain to me why you consider it so important?

In my opinion a 19 + 20kHz IMD is way more interesting and relevant, but still there is no need to test at full power. And no I don't use that as an excuse for class d as I showed you running my amps at full power at 20kHz.

 

[DonH56]

Heck, you can't get a square wave out of an amplifier of any bandwidth. Square waves can be used to elicit bad behaviour out of amplifiers with specific design issues, but they are otherwise useless as a metric of quality.
The square wave as reproduced by the amplifier is exactly defined by the frequency response of that amplifier, and indeed one can be trivially derived from the other. It is a matter of convenience in representation. You would be very hard pressed to visually glean the aurally important information presented in the frequency response from a square wave reproduction, so it makes sense to use the frequency response representation.

Not an ideal square wave, but pretty close... Stability (in bold) is the main reason we (I, anyway, though I suspect others like @restorer-john have the same reasons) advocate for square-wave testing. And input to output bandwidth is not always indicative of stability there may be problems with internal stages and the feedback loop(s) that an output bandwidth measurement does not show. I just want to hit it with a wideband input to check it doesn't do anything weird; a 1 kHz square wave with a fast edge (1 us or so) is what I have used in the past. And not necessarily full-scale since frequency response tends to be wider at lower power.

I think @amirm argues similarly with respect to frequency response providing the same information, and additionally in his experience (pretty extensive at this point) modern amplifiers do not (or rarely) exhibit stability problems so it is a waste of his time to run the test. Especially since it requires a different setup than his standard tests. It is his time and equipment, so I do not fault him for that at all, but personally would like to see some sort of square-wave or similar test "just for grins".

I would not degrade the power bandwidth vs. THD test myself. I agree with John that it is a standard, and is another thing that can distinguish among amplifiers' performance.

FWIWFM - Don

 

[March Audio]

Not an ideal square wave, but pretty close... Stability (in bold) is the main reason we (I, anyway, though I suspect others like @restorer-john have the same reasons) advocate for square-wave testing. And input to output bandwidth is not always indicative of stability there may be problems with internal stages and the feedback loop(s) that an output bandwidth measurement does not show. I just want to hit it with a wideband input to check it doesn't do anything weird; a 1 kHz square wave with a fast edge (1 us or so) is what I have used in the past. And not necessarily full-scale since frequency response tends to be wider at lower power.

I think @amirm argues similarly with respect to frequency response providing the same information, and additionally in his experience (pretty extensive at this point) modern amplifiers do not (or rarely) exhibit stability problems so it is a waste of his time to run the test. Especially since it requires a different setup than his standard tests. It is his time and equipment, so I do not fault him for that at all, but personally would like to see some sort of square-wave or similar test "just for grins".

I would not degrade the power bandwidth vs. THD test myself. I agree with John that it is a standard, and is another thing that can distinguish among amplifiers' performance.

FWIWFM - Don

Shouldn't standards evolve?