ATI AT2000 amps

[AcuDefTechGuy]

It just doesn't seem fair.

The Crown XLS 1500 is $350 delivered, and it's 300wpc x 2ch 8ohm, 525wpc x 2ch 4ohm, & 775wpc x 2ch 2ohm. And it weighs 8lbs, not 80lbs. And it's silent to my ears. I can't even hear the fan noise. The fan noise was my main concern.

A comparable ATI, Parasound, Sunfire, etc, 300wpc stereo amp would be like $2K.

The Emotiva XPA-2 is $800 for 300wpcx 2ch.

I guess the pro amps just look kind of ugly, as already mentioned.

 

[GranteedEV]

It just doesn't seem fair.

The Crown XLS 1500 is $350 delivered, and it's 300wpc x 2ch 8ohm, 525wpc x 2ch 4ohm, & 775wpc x 2ch 2ohm. And it weighs 8lbs, not 80lbs. And it's silent to my ears. I can't even hear the fan noise. The fan noise was my main concern.

A comparable ATI, Parasound, Sunfire, etc, 300wpc stereo amp would be like $2K.

The Emotiva XPA-2 is $800 for 300wpcx 2ch.

It's totally fair.

People who let their biases (IE Hi-Fi company, built in USA, looks like it weighs 100lbs, weighs 100lbs) dominate their decisions, pay more.

People who buy what I tell them to buy, pay less.

 

[AcuDefTechGuy]

It would be nice if Audioholics, Stereophile, Home Theater Magazine would review/measure these amps, like the Crown XLS amps. Can they truly output 1000-2000wpc RMS?

 

[cpp]

It would be nice if Audioholics, Stereophile, Home Theater Magazine would review/measure these amps

Maybe their not hip enough or have outrageous cost to earn a review. I'm like you maybe it's time for mag's like Stereophile and HTM to do more reviews on equipment be it speakers, amps, etc.. that don't cost as much as a small car. Come down to the working man's (or retired persons) salary.

 

[Irvrobinson]

It would be nice if Audioholics, Stereophile, Home Theater Magazine would review/measure these amps, like the Crown XLS amps. Can they truly output 1000-2000wpc RMS?

I'm actually more interested in what they do when the output level is 1-2 watts.

 

[AcuDefTechGuy]

I'm actually more interested in what they do when the output level is 1-2 watts.

I don't get it.

Most measurements (THD, XT, SNR) are done @ 1watt, right?

Isn't 300wpc/500wpc/1000wpc more important?

 

[Irvrobinson]

I don't get it.

Most measurements (THD, XT, SNR) are done @ 1watt, right?

Isn't 300wpc/500wpc/1000wpc more important?

If you look at some comprehensive test reports you'll see rising distortion proportions at lower power levels. Unless you're listening to highly compressed rock or just using the amp for a subwoofer, a great proportion of home listening is done at 1-2W. For these pro amps, which are often intended to be used for sound reinforcement, I would like to see that they haven't sacrificed any purity at low power levels to stuff as many watts at they can into a small package for a low price. Perhaps great measurements at 1W wasn't a priority because the amp is intended for environments where that isn't important. Maybe they are near-perfect at 1W, but it would just be nice to see it verified. Even your mentor Aczel doesn't dismiss the possibility that two amps can sound different, he just dismisses the possibility that two amps that measure the same can sound different.

 

[GranteedEV]

It would be nice if Audioholics, Stereophile, Home Theater Magazine would review/measure these amps, like the Crown XLS amps. Can they truly output 1000-2000wpc RMS?

Honestly, I have no clue.... but let's say, maybe the XLS2500 is inflated on the spec sheet. Let's say it only does...oh... 80% of what it's rated under "strict Audioholics testing conditions".

... isn't that still better than the alternatives?
... and does actual music content represent those strict testing conditions?

I think the fact that they actually give you stable 4 ohm and 2 ohm ratings, matters more than whether they "meet spec to a tee". 620W instead of 775W watts for example, is still a **** ton of power for $550!

 

[GranteedEV]

If you look at some comprehensive test reports you'll see rising distortion proportions at lower power levels.

Careful with this one. Often this "rising distortion at lower power levels" is simply the noise floor not only of the electronic, but the measurement tool, becoming more obvious on a graph.

For these pro amps, which are often intended to be used for sound reinforcement, I would like to see that they haven't sacrificed any purity at low power levels to stuff as many watts at they can into a small package for a low price.

Class D amps like the crown fundamentally don't have crossover distortion common in class AB designs like the ATI and Emotiva etc.

Perhaps great measurements at 1W wasn't a priority because the amp is intended for environments where that isn't important.

Don't forget also that these amps are made to drive highly sensitive (>95db) speakers. So 1 watt translates to around 80-85db in many PA environments.

Maybe they are near-perfect at 1W, but it would just be nice to see it verified.

I agree. It'd be nice if Gene would measure an XLS1500 for us

 

[Irvrobinson]

Careful with this one. Often this "rising distortion at lower power levels" is simply the noise floor not only of the electronic, but the measurement tool, becoming more obvious on a graph.

Sometimes, but with the latest AP analyzers?

Class D amps like the crown fundamentally don't have crossover distortion common in class AB designs like the ATI and Emotiva etc.

They have other challenges...

Don't forget also that these amps are made to drive highly sensitive (>95db) speakers. So 1 watt translates to around 80-85db in many PA environments.

People don't build or buy 1000W compact amplifiers to put out 85db, they're buying them for high volume levels in large spaces. I agree that many PA and sound reinforcement speakers are horn-loaded and quite efficient, and maybe the designers are ensuring the amps are pure at 1W, but this is easy to verify.

I agree. It'd be nice if Gene would measure an XLS1500 for us

Exactly!

 

[DS-21]

It just doesn't seem fair.

The Crown XLS 1500 is $350 delivered, and it's 300wpc x 2ch 8ohm, 525wpc x 2ch 4ohm, & 775wpc x 2ch 2ohm. And it weighs 8lbs, not 80lbs. And it's silent to my ears. I can't even hear the fan noise. The fan noise was my main concern.

A comparable ATI, Parasound, Sunfire, etc, 300wpc stereo amp would be like $2K.

The Emotiva XPA-2 is $800 for 300wpcx 2ch.

I guess the pro amps just look kind of ugly, as already mentioned.

Price/performance-wise the only place "home" amps are remotely competitive to the newest generation of "pro" amps is in multichannel formats. And that simply because the pro market doesn't demand 5+ channels in a single chassis.

Yes, there are some more expensive 5+ channel pro models, such as the 1 RU (!) LexiCrown* at 125Wx8 (into 4Ω or 8Ω), the Ashly amps with or without DSP, the Powersoft Ottocanalis, and of course my new favorite amp, the ElectroVoice CPS 8.5. But most of them don't have 12V triggers (the LexiCrown and EV ones do) and also there's the fan issue. But still, it'll generally either cost more or take more real estate (or both) to match a decent entry-level NRTL-certified home multichannel amp, such as an Anthem PVA7. (Nobody, of course, should be considering non-NRTL certified amp. The pro amps are all as a rule NRTL certified, because their market isn't filled with as many ignorant soothsayers as the home audio market. Well, maybe Behringer's aren't. I've never been interested in buying one, so I've never looked...)

But for people who can hide their amps and have enough space for a tall rack, the only thing one loses by going pro is...well, nothing.


*I use "LexiCrown" as a shorthand for the Lexicon DD-8 and Crown CT8150 twins. It's also worth noting that, unlike Lexicon's naked attempt at rent-seeking with the LexOppo BDP-83, the LexiCrown is more befitting of a company like Harman: same basic part, but with I/O and front panel tailored to it brand's market, and sold for about the same price through both sales channels.

It would be nice if Audioholics, Stereophile, Home Theater Magazine would review/measure these amps, like the Crown XLS amps. Can they truly output 1000-2000wpc RMS?

I wish Azcel would. Anyone know his e-mail address? I'd like to write him about them. I'd like to see a Crown XLS Drivecore and a Peavey IPR on his Powercube.

Azcel did review a QSC amp a while back. He and Dr. Rich disagreed as to its merits in a home audio system.

I'm actually more interested in what they do when the output level is 1-2 watts.

There's really no rational reason to expect a modern amp to be less linear at low power levels than a 1970s-era circuit...

Even your mentor Aczel doesn't dismiss the possibility that two amps can sound different, he just dismisses the possibility that two amps that measure the same can sound different.

Of course they can sound different. But they usually don't.

Honestly, I have no clue.... but let's say, maybe the XLS2500 is inflated on the spec sheet. Let's say it only does...oh... 80% of what it's rated under "strict Audioholics testing conditions".

It is Crown, so I'd expect the ratings to be honest.

The Peavey IPR 1600 has been tested, here and in Germany, and are rated honestly. The Berry NU3000 has been tested in Germany, and measured like the IPR 1600 knockoff it is.

They have other challenges...

Only the output filter issue. One reason why, perhaps many Class D amps are best used either for subs, in multiamped speakers with active crossovers designed based on measurements while the tweeters are powered by those amps, or in concert with room correction systems that work over the full bandwidth.

People don't build or buy 1000W compact amplifiers to put out 85db, they're buying them for high volume levels in large spaces.

Nobody I know who owns the McIntosh 1kW monoblocs really rocks out with them... (And I've been in several homes with those, or the slightly smaller ones.)

 

[Irvrobinson]

Nobody I know who owns the McIntosh 1kW monoblocs really rocks out with them... (And I've been in several homes with those, or the slightly smaller ones.)

I said compact 1000W amps. The McIntosh is hardly compact.

Only the output filter issue. One reason why, perhaps many Class D amps are best used either for subs, in multiamped speakers with active crossovers designed based on measurements while the tweeters are powered by those amps, or in concert with room correction systems that work over the full bandwidth.

Exactly.

 

[GranteedEV]

Exactly.

THis is the case with some, yes, but not all class D amps. Easy to paint a broad brush

 

[DS-21]

Exactly.

On reflection, my statement was extreme. Here's a graph showing a typical Class D amp output filter with an F3 of 39kHz optimized for a 4Ω load, as for whatever reason many current Class D amp seem to be. The difference in top-end output at 20Hz between a 16Ω load and a 4Ω load is maybe 3 or 4 dB. At 10kHz it's de minimis.

(source.)

Though I guess you could say dumping twice the average power into a 16Ω tweeter may fry it. Now show me the home audio speaker with a tweeter that is (a) 16Ω from 10-20 kHz; and (b) not a compression driver designed for drive levels way higher than seen in home audio.

For a real-world example, the Tools4Music review of the Berry NU3000 shows a 2dB rise at 20kHz into an 8Ω load (at 26). So one would expect similar from the Peavey IPR.

That might be audible when the amp's running full range, but just barely. A couple dB variance at 20kHz isn't as perceptually meaningful as a fractional dB variance in midrange!

Furthermore, amp designs like Hypex's don't vary in FR with performance, and they're very compact, too. I'm not sure where the output filter is in the Crown/TI DriveCore designs.

 

[AcuDefTechGuy]

Here is the Audio Critic review of the cheap $200 Behringer amp:


http://theaudiocritic.com/plog/index.php?op=Default&blogId=1&&page=3

Peter Aczel liked it enough.

" The PowerCube of the A500 is shown in Fig. 1. There is basically nothing wrong with it. The sloping characteristic of the top of the polyhedron merely shows that the power supply is limited. Into an 8Ω load with a 0° phase angle (purely resistive) the maximum output is a little over 33 volts at the test limit of 1% distortion, which translates to 138 watts. Into 4Ω/0° the maximum output is a hair under 30 volts, equivalent to 220 watts, and then successively less into 2Ω and 1Ω. The output holds up extremely well, however, into capacitive (–) and inductive (+) phase angles at each impedance, which is most unusual in an inexpensive amplifier. A more nearly cubical picture could be drawn only by an amplifier with a much heavier power supply.... The Behringer A500 is an amazing phenomenon at the price. There is nothing else like it. I’ll tell you what. If you need a new power amplifier, or maybe just a spare amplifier, throw caution to the wind. Be the last of the big-time spenders."

 

[Irvrobinson]

THis is the case with some, yes, but not all class D amps. Easy to paint a broad brush

I said it was a challenge, I didn't say it wasn't solvable, no more than any other product development problem is.

 

[DS-21]

Here is the Audio Critic review of the cheap $200 Behringer amp:


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Your link goes to a different article, though there is a line in the post to which you linked that is well-worth repeating:

"Products like that are rare, however. Most have no distinguishing attributes, no matter how hard the admen try."

To put it another way, most audio electronic components are just commodity parts.

Here's the link for the Berry (Class AB) amp review.

FWIW, the review to which I was referring was one of the QSC DCA 1222 an AB amp with a switch-mode power supply, in the old print magazine issue 28, at 32. Here, is what the meat of the review:

***The amplifier has separate front- panel gain controls for each channel, and I found that a 20 x (26 dB) gain setting resulted in the lowest distortion. With that setting, into an 8Ω load, the purely noise-dominated THD+N curves bottomed out at -98 dB, -93 dB, and -77 dB with inputs of20 Hz, 1 kHz, and 20 kHz, respectively, just before the clipping point of 200 watts. Into 4Ω, clipping occurred at 370 watts, and the minima at same frequencies were -91 dB, -87 dB, and -75 dB. That's a truly excellent result, except at 20 kHz, where some not very important dynamic distortion is apparent. Frequency response at 1 watt into 8Ω measured -0.34 dB at 10 Hz and 20 kHz; the -1 dB point was 37 kHz. Channel separation at 1 watt into 8Ω ranged from 61 dB at 20 kHz in the less good channel to 95 dB at 350 Hz in the better channel, with 77 dB or better at all frequencies below 3 kHz in either channel. Good enough.

The PowerCube test, exclusive to The Audio Critic in the U.S.A., feeds short (20 ms) tone bursts of 1 kHz through the amplifier into 20 different resistive and reactive loads to determine maximum dynamic power at 1 % distortion. Dynamic power is nearly always greater than continuous power. The DCA 1222 showed excellent behavior with 8Ω/4Ω/2Ω loads at -60°/-30°/0°/+30°/+60°
declining but still decent output into 1Ω loads at the same phase angles. Into 8Ω/0° dynamic power was 252 watts. I haven't seen a better PowerCube at this price and then some.

Regular readers of The Audio Critic know that we don't go into specifics about the sound of a well-designed amplifier, since it is the same as that of any other well-designed amplifier, but in the case of the DCA 1222 it should be mentioned that the sound of the cooling fan is occasionally audible in a quiet room. David Rich (see the sidebar) is unenthusiastic about the use of this amplifier for consumer applications but he forgets that very few, if any, home hi-fi amplifiers give you so much clean power for only a little over a dollar a watt (when you count both channels into 4Ω).

And here's Dr. Rich's opinion, following his circuit analysis:

In summary, it is light, swings lots of current, cannot blow up, and has some dynamic distortion. Good for sound reinforcement applications, but ultimately other choices are better for consumer applications.

 

[Irvrobinson]

On reflection, my statement was extreme.

Perhaps, but my "exactly" was just because you described the primary design challenge well. I'm not judging solutions, I was responding to Grant's implication that Class D amplifiers have an advantage over Class AB amps by not having crossover distortion. And my only point is that they do have other challenges. BTW, I'm not intending to argue in favor of Class A or AB designs. The fact that I bought one was just indicative of a low-risk approach on a product I had the chance to hear and examine in person. I think the evidence is mounting that in ten years the only part of the high-end audio market that will probably exist is speakers.

 

[AcuDefTechGuy]

So the Audio Critic thinks the pro amps they've reviewed/ measured sound just as good as all these "home" amps.

The fan noise is an issue with a lot of these pro amps.

Although I did not hear any noise with the Crown XLS amps.

 

[GranteedEV]

So the Audio Critic thinks the pro amps they've reviewed/ measured sound just as good as all these "home" amps.

The fan noise is an issue with a lot of these pro amps.

Although I did not hear any noise with the Crown XLS amps.

What about electronic noise floor? Was it higher than your other amps?