My experiance with a Crown XLS power amp

[PENG]

The "measurers" claim that if you can't put repeatable measurements on something, then it doesn't exist. This is stupidity at its most intransigent.

Who are they? Was that kind of claim taken out of context, did such "measurers" qualify their statements with specifics? If they did, then I wouldn't know if I would agree with your "stupidity...." comment without seeing the whole thing.

The human brain is far more competent and subtle. An example I use is that you're walking down a crowded city street and hear music from a couple of blocks over. Despite the traffic noise and the multiple other noises distracting you, your brain knows instantly whether the music is live or recorded. No question, no hesitation, your brain knows. Measure THAT for me!

I am not sure about the relevance in this. The difference between "live" and especially where no electronic gear is involved, and reproduced music at home is in fact huge, to the point even the half deaf would know the difference without measurements. Also true but to a lesser extent when comparing loudspeakers, say a pair of Revel Salon 2 to a pair of their entry level book shelf monitors under any conditions. In such comparison, no measurements would be needed to support the human brains.

To compare a XLS 2502 to an AVR such as a lowly AVR-X3500H with flimsy heat sinks in pure direct mode, when used well below their limits is a different story. In that case, I would go with measurements and not someone else subjective impressions. Measurements would then tell me at least the following:

At 5 W, the Denon receiver would have significantly lower distortions that the XLS 2502, about 0.0086% vs 0.0323%. At >150 W output (into 4 ohms two channel driven), the XLS 2502 would perform much better as the receiver would begin to clip.

So up to 100 W output level, we know the THD+N of the Crown amp would be almost 4 times higher (at lower levels) than that of the receiver. In terms of the threshold of audibility, it probably won't make a difference to most people, but iirc there were studies that indicated the Crown's THD+N level of 0.0323% may be discernible under some conditions, by some people.

On the subjective side, if someone tells me adding that Crown amp to a receiver such as the measured AVR-X3500H made a night and day difference even at low listening level, I would just say good for him/her and I won't utter the word "Placebo effect".

Again, of course, ymmv.. I am simply trying to understand your points and my observations.

 

[Boomzilla]

I am not sure about the relevance in this...At 5 W, the Denon receiver would have significantly lower distortions that the XLS 2502, about 0.0086% vs 0.0323%. At >150 W output (into 4 ohms two channel driven), the XLS 2502 would perform much better as the receiver would begin to clip.

So up to 100 W output level, we know the THD+N of the Crown amp would be almost 4 times higher (at lower levels) than that of the receiver. In terms of the threshold of audibility, it probably won't make a difference to most people, but iirc there were studies that indicated the Crown's THD+N level of 0.0323% may be discernible under some conditions, by some people...

So let's make it real, @PENG - The average loudspeaker these days has a sensitivity of approximately 90dB / 1w / 1m. The average listener uses less than one watt for the vast majority of their listening.

So let's compare the AVR and the XLS at ONE watt - this is a real-world comparison. ANYONE who listens consistently to home audio using 100 watts (or even 10) is probably so deaf that the distortion of their amp is academic.

There's no doubt that pro amps can put out LOTS of power, but that "virtue" is academic for almost all home listening. How an amplifier sounds in that critical first watt is what defines the sound.

And let's not forget that with the Crown, we aren't just measuring the distortions of the amplifier section, we're also including the distortion of their cheap A-D and D-A converters. Taken as a package, I stand by my statement that Crown XLS amps are not even remotely suitable for home audio.

 

[sterling shoote]

OP, I used to operate (6) Sony TA-N 55ES Power Amps in bridged mode to power my 5.1 system. I was very pleased; however, 300 watts in bridged configuration was not enough power to my JBL B380 subwoofer to preclude clipping on ocassion; so, I hooked the sub up to a Sony TA-N80ES Power Amp in bridged mode, which puts out 560 watts to the 600 watt rated sub, and no more clipping. At any rate, haveI not had any problems with my amps or speakers when operating amps in bridged mode. I think you bought a magnificent amp for stereo or mono pleasure. I've been thinking about buying what you've purchased to replace the TA-N80ES for subwoofer power so I hope to read the rest of your review/thoughts about it all.

 

[PENG]

So let's make it real, @PENG - The average loudspeaker these days has a sensitivity of approximately 90dB / 1w / 1m. The average listener uses less than one watt for the vast majority of their listening.

So let's compare the AVR and the XLS at ONE watt - this is a real-world comparison. ANYONE who listens consistently to home audio using 100 watts (or even 10) is probably so deaf that the distortion of their amp is academic.

There's no doubt that pro amps can put out LOTS of power, but that "virtue" is academic for almost all home listening. How an amplifier sounds in that critical first watt is what defines the sound.

And let's not forget that with the Crown, we aren't just measuring the distortions of the amplifier section, we're also including the distortion of their cheap A-D and D-A converters. Taken as a package, I stand by my statement that Crown XLS amps are not even remotely suitable for home audio.

So I guess we are in agreement then after all.. To HD, I am not saying adding a XLS amp to a mid range AVR such as D+M and Yamaha's will audibly degrade SQ, just that I see no gain if one wants an amp that matches such AVR's audio specs and measurements. The gain will obviously be the raw power output if needed.

 

[Verdinut]

class-A circuitry if you can get it - The XPA-1s do about 60 watts before sliding into class AB.

Where did you get that info about outputting 60 watts before operating in Class AB? Only a few of the expensive Class AB amplifiers operate in Class A for about 10 watts at best. @PENG will be able to give you more precise info on that.

 

[lovinthehd]

So I guess we are in agreement then after all.. To HD, I am not saying adding a XLS amp to a mid range AVR such as D+M and Yamaha's will audibly degrade SQ, just that I see no gain if one wants an amp that matches such AVR's audio specs and measurements. The gain will obviously be the raw power output if needed.

No worries, I don't use my Crowns on any of my avrs at this time anyways, but had no issues when I did. If Boomzilla can hear that miniscule difference in distortion specs, great, but you'd have to prove it to me with a dbx test that the golden ears can actually do it.

ps I'd also like to have Boomzilla prove his hearing on his ability to discern dac quality by how much it cost

 

[Boomzilla]

Any DAC beyond the bottom of the barrel and I'd be unable to hear any difference, I'm sure. But unnecessary A-D / D-A conversions I can hear. Further, even the use of DSP without any additional A-D or D-A conversions messes up the sound. I've noticed it in J-River; I've noticed it Roon; I've noticed it in Auralic's Lightning DS Streamer software. The less one tampers with the signal (in either the digital OR the analog domain), the better the sound.

As to power being needed for subwoofers, YES - I'd agree, AND the quality of the midrange and treble are totally academic for subwoofer use. In fact the amplifier's distortion rating is probably also academic because most subwoofer drivers put out an order of magnitude more distortion than their amplifiers.

The bottom line is I know what I hear - I'm confident that my impressions are accurate - I say what I hear. You're welcome to disagree and to the best of your experience, I'm sure that you're telling the truth. But there IS an objective truth beyond both of our opinions. Regarding the Crown XLS series, even the measurements skew toward my opinion over yours (and Andrew Robinson's).

 

[Boomzilla]

Where did you get that info about outputting 60 watts before operating in Class AB? Only a few of the expensive Class AB amplifiers operate in Class A for about 10 watts at best. @PENG will be able to give you more precise info on that.

That information comes from the Secrets of Home Theater and High Fidelity website where their reviewer (backed up by measurements) says "The updated model improves on this by delivering 600 watts into 8 ohms and 1,000 watts into 4 ohms. It also offers a Class A mode accessible by a switch on the front panel. When engaged, this provides 60 watts of Class A, but retains the ability to provide up to 600 watts in Class A/B mode."

See for yourself here: https://hometheaterhifi.com/reviews/amplifier/power-amplifier/emotiva-xpa-1-gen-2-monoblock-power-amplifier-review/

The Generation 2 Emotiva XPA-1 is NOT a typical "expensive Class AB amplifier operating in Class A for about 10 watts at best." The XPA-1 DOES put out a full 60 watts in Class-A (and sounds NOTHING like a damned Crown XLS series amp while doing it).

 

[lovinthehd]

Any DAC beyond the bottom of the barrel and I'd be unable to hear any difference, I'm sure. But unnecessary A-D / D-A conversions I can hear. Further, even the use of DSP without any additional A-D or D-A conversions messes up the sound. I've noticed it in J-River; I've noticed it Roon; I've noticed it in Auralic's Lightning DS Streamer software. The less one tampers with the signal (in either the digital OR the analog domain), the better the sound.

As to power being needed for subwoofers, YES - I'd agree, AND the quality of the midrange and treble are totally academic for subwoofer use. In fact the amplifier's distortion rating is probably also academic because most subwoofer drivers put out an order of magnitude more distortion than their amplifiers.

If I took your dbx test, @lovinthehd, and scored perfectly on a hundred sequential tests, you'd still find some nit to pick. So I don't have to "prove" anything to you. You don't want proof - you seem to want to be a horse's back end. And you're succeeding.

I had an audiogram this year and the audiologist praised my lack of presbyacusis and the sensitivity of my ears. When was the last time that YOU had an audiogram?

The bottom line is I know what I hear - I'm confident that my impressions are accurate - I say what I hear. You're welcome to disagree and to the best of your experience, I'm sure that you're telling the truth. But there IS an objective truth beyond both of our opinions. Regarding the Crown XLS series, even the measurements skew toward my opinion over yours (and Andrew Robinson's).

You're the one with the claims. No, if you could pass a proper double blinded test I'd be happy, but I doubt you could and seems you rely heavily on sighted comparisons. I just don't see the value in your anecdotal determination, particularly the fine level of distortion you claim to be able to discern. You could take the test where a track is looped thru a ADC/DAC loop several times, see if you can pass that one first. Maybe you do have golden ears, the odds aren't with you on that, though. Good luck with your continued limited presbyacusis, but mostly its about what goes on in the brain, rather than the self-determined audiophile hearing capabilities.

 

[Verdinut]

That information comes from the Secrets of Home Theater and High Fidelity website where their reviewer (backed up by measurements) says "The updated model improves on this by delivering 600 watts into 8 ohms and 1,000 watts into 4 ohms. It also offers a Class A mode accessible by a switch on the front panel. When engaged, this provides 60 watts of Class A, but retains the ability to provide up to 600 watts in Class A/B mode."

See for yourself here: https://hometheaterhifi.com/reviews/amplifier/power-amplifier/emotiva-xpa-1-gen-2-monoblock-power-amplifier-review/

The Generation 2 Emotiva XPA-1 is NOT a typical "expensive Class AB amplifier operating in Class A for about 10 watts at best." The XPA-1 DOES put out a full 60 watts in Class-A (and sounds NOTHING like a damned Crown XLS series amp while doing it).

That's different than what you were implying. When the XPA-1 is switched to the Class A position, it's no longer operating as a true Class AB amplifier. It would then be a pure Class A amplifier.

 

[Boomzilla]

That's different than what you were implying. When the XPA-1 is switched to the Class A position, it's no longer operating as a true Class AB amplifier. It would then be a pure Class A amplifier.

Actually, no. Even in "Class-A" mode, the Emotiva XPA-1 amp transitions automatically to Class AB beyond its first 60 watts. So the amp does have two modes:

"Normal mode," where the bias is sufficient to provide the usual first 10 watts or so of Class A beyond which it transitions automatically to Class AB, and

"Class-A mode," where the increased bias is sufficient to provide 60 watts of Class A beyond which it transitions automatically to Class AB.

A "real" Class A mode amp would just clip if its input signal demanded more output than what its Class-A output capabilities could deliver. So in both modes, the Emotiva amp is still a "sliding Class-A / Class-AB" amplifier - not a true Class-A one.

Real class A amplifiers are rare due to the amount of heat that must be dissipated. I've always wondered why liquid cooling hasn't been employed for class A amplifiers. Computer CPUs can be liquid cooled, and at the low temperatures which they operate, they can be "overclocked" to provide significantly higher clock speeds. With "sandwich" cooler plates on both sides of audio-output transistors, both plates being cooled with refrigerated liquid, it would seem that truly high-powered, fully class-A amplifiers would be feasible. I wonder why nobody's ever tried that...

Boomzilla

 

[Boomzilla]

You're the one with the claims. No, if you could pass a proper double blinded test I'd be happy, but I doubt you could and seems you rely heavily on sighted comparisons. I just don't see the value in your anecdotal determination, particularly the fine level of distortion you claim to be able to discern. You could take the test where a track is looped thru a ADC/DAC loop several times, see if you can pass that one first. Maybe you do have golden ears, the odds aren't with you on that, though. Good luck with your continued limited presbyacusis, but mostly its about what goes on in the brain, rather than the self-determined audiophile hearing capabilities.

You don't see the value because, apparently, you're not basing what you believe on what you hear. Instead, you're convinced that if there isn't written "scientific proof," then it doesn't exist. I think that this is a fallacy.

And it may not be simple distortion that I'm hearing. All of the AD and DA converters on the market change the actual frequency response of the signal passing through them - not just the distortion characteristics. There's also the ever-present and measurable phase shift that occurs every time that steep, digital low-pass filtering is applied (and it is, both in AD and DA converters). Such phase shift is cumulative, from the original recording, through mastering and equalization, to the consumer, and through the playback chain.

I don't have golden ears (or presbyacusis), although you keep trying to imply that I have both. I just don't see the value in your insistence that blind testing is the gold standard for discerning differences in audio. Published studies have debunked the notion. Short-term clips in rapid-fire A/B presentation are insufficient for difference determination. But why confuse you with facts? Your mind's made up.

Believe what you want - The differences I'm hearing are there because I (and others) can hear them. If you trusted your own ears instead of pseudo-data, then you might hear them as well - or not. But my point is that just because you can't hear something doesn't prove that it isn't real.

 

[Verdinut]

"Class-A mode," where the increased bias is sufficient to provide 60 watts of Class A beyond which it transitions automatically to Class AB.

A "real" Class A mode amp would just clip if its input signal demanded more output than what its Class-A output capabilities could deliver. So in both modes, the Emotiva amp is still a "sliding Class-A / Class-AB" amplifier - not a true Class-A one.

And the output stage of the amplifier operating in Class AB is also biased to annul the crossover distortion that would occur if it just operated in Class B. Actually, some Class AB amplifiers continually operate in Class AB and that's OK too.

Unless someone has golden ears, there's no audible difference between Class A and a well designed Class AB output stage.

 

[Out-Of-Phase]

"With "sandwich" cooler plates on both sides of audio-output transistors, both plates being cooled with refrigerated liquid, it would seem that truly high-powered, fully class-A amplifiers would be feasible. I wonder why nobody's ever tried that..."

Why don't you try it and stop your trolling.

 

[PENG]

Instead, you're convinced that if there isn't written "scientific proof," then it doesn't exist. I think that this is a fallacy.

I agreed with you on a few things so far but not this one. Your argument may apply to things like climate change, other environmental concerns/claims etc., but for audio power amplifiers that is in fact a science/engineer based products designed and built by humans, then of course if a claim such as one amp is more transparent/accurate than another under a specified conditions cannot be proved scientifically (example: by measuring parameters that support transparency/accuracy), then the claimed benefits (example: audible differences) does not exist. So I guess we can at least agree to disagree on this one, assuming I understood what you were saying.

 

[PENG]

And the output stage of the amplifier operating in Class AB is also biased to annul the crossover distortion that would occur if it just operated in Class B. Actually, some Class AB amplifiers continually operate in Class AB and that's OK too.

Unless someone has golden ears, there's no audible difference between Class A and a well designed Class AB output stage.

Agreed, and I would think that crossover distortion should no longer considered a bottleneck for modern well designed class AB amps. Recent models of some relatively expensive amps such as Bryston's apparently are no longer biased to operate in "A" for more than a watt, or even less. I bet even Nelson Pass would agree with us on this.

 

[M Code]

Regarding the sonics of various amplifiers & topologies... This Stereophile article with Carver has some interesting observations..

Carver Challenge Responses

Responses to the 1985 "Carver Challenge" (from February 1986, Vol.9 No.1):

www.stereophile.com

Just my $0.02...

 

[lovinthehd]

You don't see the value because, apparently, you're not basing what you believe on what you hear. Instead, you're convinced that if there isn't written "scientific proof," then it doesn't exist. I think that this is a fallacy.

And it may not be simple distortion that I'm hearing. All of the AD and DA converters on the market change the actual frequency response of the signal passing through them - not just the distortion characteristics. There's also the ever-present and measurable phase shift that occurs every time that steep, digital low-pass filtering is applied (and it is, both in AD and DA converters). Such phase shift is cumulative, from the original recording, through mastering and equalization, to the consumer, and through the playback chain.

I don't have golden ears (or presbyacusis), although you keep trying to imply that I have both. I just don't see the value in your insistence that blind testing is the gold standard for discerning differences in audio. Published studies have debunked the notion. Short-term clips in rapid-fire A/B presentation are insufficient for difference determination. But why confuse you with facts? Your mind's made up.

Believe what you want - The differences I'm hearing are there because I (and others) can hear them. If you trusted your own ears instead of pseudo-data, then you might hear them as well - or not. But my point is that just because you can't hear something doesn't prove that it isn't real.

Well that's a stretch. I don't particularly base "belief" on what I hear. I hear what I hear. I just say I don't find your particular description/conclusion particularly interesting as it is simply your belief.

I have no idea what you're hearing and my bet is either do you. You latch on to so many reasons, amp class, handling of digital data that you've "seen" personally it seems to color your experience. My point is I don't think you can hear what you think you can hear in a fair comparison rather than the ones loaded with bias expectation you seemingly prefer. Old audiophile nonsense, may as well talk about how you hear cabling.

No one has debunked any such thing....and your argument is like that of a salesman/shill to my reading. You can believe/hear what you want, but I don't have to give it any credibility unless you could prove your "abilities".....which I doubt you can.

 

[Boomzilla]

...Unless someone has golden ears, there's no audible difference between Class A and a well designed Class AB output stage.

My friend, who has the Generation 2 Emotiva XPA-1 power amplifiers, and who is able to swap between Class A and Class AB at the flip of a switch, disagrees with you. Unless you're claiming that Emotiva does NOT have a "well designed Class AB output stage?" I've listened to his system, and to my ears, you're right - I hear no difference (at the levels that I listen at) between the Class A and Class AB modes. But he (and his wife) do. They leave the amps on idle in Class AB, but always swap to Class A before listening.

Maybe if I spent a LOT of time listening to his system, I could teach myself to pick out the tiny differences between the two output modes of the amplifiers, but as of now, I couldn't do it in any double-blind test.

My conclusion from the above? Maybe I don't need to spend any money on Class A topography...

 

[Verdinut]

My friend, who has the Generation 2 Emotiva XPA-1 power amplifiers, and who is able to swap between Class A and Class AB at the flip of a switch, disagrees with you. Unless you're claiming that Emotiva does NOT have a "well designed Class AB output stage?" I've listened to his system, and to my ears, you're right - I hear no difference (at the levels that I listen at) between the Class A and Class AB modes. But he (and his wife) do. They leave the amps on idle in Class AB, but always swap to Class A before listening.

Maybe if I spent a LOT of time listening to his system, I could teach myself to pick out the tiny differences between the two output modes of the amplifiers, but as of now, I couldn't do it in any double-blind test.

My conclusion from the above? Maybe I don't need to spend any money on Class A topography...

As a matter of fact, you should not hear a difference between Class A and Class AB if both amplifiers operate within their rated output limits. Only people who claim to hear a difference might have "golden ears" and are unable to prove it with double blind tests.