Today I picked up my Atma-Sphere Class D Amps. These aren’t broken in yet. And they are simply amazing. I’ve listen to a lot of High End Class D. Some that cost many times what Atma-Sphere Class D costs. I wasn’t a fan of any of them. But these amps are amazing. I really expected to hate them. So my expectations were low. The Details are of what I’ve never heard from any other amps. They are extremely neutral. To say the realism is is extremely good is a gross understatement. They are so transparent it’s scary. These amps just grab you and suck you into the music. After I live with them some and get them broken in. And do some comparisons to some other high end Amps Solid State, Tubes and Class D’s, also in other systems I’ll do a more comprehensive review. But for now, these are simply amazing amps.. Congrats to Ralph and his team. You guys nailed on these.
A well designed shootout among the leading or most popular class D amps would be very interesting, but getting conclusive results on such a highly subjective thing as how things "sound" is always problematic.
That leaves one to merely leverage both the two tools one has at their disposal to decide.....what they read including specs then always most importantly in the end what they hear.
Since everyone hears differently and also has unique goals and preferences, there is no pressure for anyone to agree with another.
At the same time, in lieu of objective measurements, no substantive conclusions regarding what is "best" or even "better" can ever be made. Each will make that determination based on the factors that matter to them. Measurements may or may not even matter in some cases.
as @mapmansays, all measurements, reviews, user comments, seller and dealer claims are neither here nor there
they are all proxies, good bad or indifferent, for how any item will perform in your own system, whether it will please you, improve the sound of the music you hear
want to really know? have to pony up, try it, listen intently, compare rigorously fairly, be honest with yourself
nothing else matters, it is all to bait the hook, so to speak... arguing is just a waste of energy time and bandwidth
different fish here snap at different bait... no one really cares what anyone else will bite at
It feels as if this whole issue of numbers and measurement is being extolled for the purpose of creating an argument. The product designer has the right to publish whatever numbers they choose. The customer has the right not to buy a product if numbers are important to them and there are no numbers to be found.
We all know that numbers often don't tell the story of how something will sound...I really like this statement from Floyd Toole because I think it captures the essence of why arguing about the validity of a product because you don't have the measurements is missing the mark:
"Audio is Art and there are aspects of the art for which we there are no scientific or technical measures yet we have little difficulty describing our reactions, positive and negative, when we hear....."
It would be of great benefit if everyone, before they post a comment, lead with whether they have heard the product they are commenting on...either in a store, at a show or in their home system. I've heard the Atmasphere class d monos at a show and said good things about them.
Anybody remember this review? Look at JA's measurements and his concluding comment, "Benchmark Media Systems' AHB2 is an extraordinary amplifier. Not only does its performance lie at the limits of what is possible for me to reliably test, it packs high power into a very small package, especially when used in bridged-mono mode. It is truly a high-resolution amplifier"
And so I ask any of you, even in October of 2015 was this really an "extraordinary amplifier". In the literal sense of the word, not ordinary, maybe. In the intended sense of the word as something superlative in terms of measurements, maybe. A "high resolution amplifier"? BS. This is where JA gets caught up as an engineer in sound floors aka distortion masking. He falsely equates resolution with bits (in his flawed DAC reviews and measurement methodology) and distortion sound levels. But my recollection is that the unwilling innocent suckers who bought the amp back in 2015-2017 based in the superlative review were by and large not thrilled. KR never could formulate reliable subjective listening impressions imho. And KR's tin ear notwithstanding, humans can not assess amplifier performance the way they can assess transducer performance-it takes long periods of time before the attributes of an amp are reliably evident.
I have no axe to grind. When I find out that there is a switching amp that thrills listeners whom I trust, I will be glad to audition one. History has shown that switching amps can ace measurement testing and bore the death out of the listener. No meat to the bones. No there there.
I’m curious why the Atmasphere Cl D amps are so low powered, compared to many others. Most D’s seem to claim fairly high power. I guess the switching power supplies are not so constrained by size and weight limitations. I had a D-Sonic, based on Pascal modules, that produced 800 watts into 8 ohms. I went back to tubes, though.
@lloydcYou just put your finger on the reason why, which is why bother if the amp won't sound like real music 😉 All that power doesn't do any good if the customer is going to go back to tubes (and lower power as a result...).
What are the cases in which measurements don’t matter?
I refer you to Daniel R. von Recklinghausen who was the chief engineer at HH Scott. He debunked, decades ago, the idea that measurements and the subjective experience are not intimately connected.
@kuribo These two statements, one right after the other, seem contradictory:
I have provided an alternative view: subjective opinions carry no factual information. We must each listen for ourselves to find our own truth.
A lawyer might ask, in a court of law, 'which is it? Were you lying then or are you lying now?' 😁 I'm not suggesting that you're lying; I am suggesting that its impossible to be truly objective.
Subjective opinions can carry quite a bit of factual information. If all those opinions say the same thing and the people producing them are unaware of each other they carry quite a bit of weight. It seems to me that you've still not made the connection of how important measurements are to the subjective experience (and I see that all the time on the subjectivist side as well...). The rules of human hearing are the reason why; as I pointed out earlier all humans use the same perceptual rules. So if we can sort out what's important to the ear, then we can make the measurements to show if we've made progress. The former is the tricky bit!
You are aware no-one is going to beat Bruno's numbers any time soon. For that reason alone I really don't see what you are so concerned about what measurements we get. If that is the only concern just buy a Purifi and be done with it. The problem I see with that I already outlined.
Our goal was to make a class D amp that could allow anyone to enjoy the music and not worry about class D, tubes, class A or any of that stuff. In that regard we feel like we succeeded. A secondary concern is that tube production is waning due to a variety of events having nothing to do with the technology. IMO tube power amps are on borrowed time right now. The rest of it I've already explained.
1) the published measurements are not sufficient or accurate enough to be useful
2) The user does not know how to properly apply the measurements
3) The user simply does not care and prefers to rely on other means to make their decisions.
I agree on point 1. Measurements ought to be much more accurate, They are currently so useless and sloppy. Ought to go to to a at least few more decimal places. We can agree on this. Or not.
Point 2 - that the user does not know. Yep. Many words could be used to describe that person. I won’t dare.
Point 3. Cool.. You have perhaps defined an audiophile - more dollars than sense. Some manufacturers rely on this aspect. And they are reading this with a mix of joy and dread in their minds.
I agree on point 1. Measurements ought to be much more accurate, They are currently so useless and sloppy. Ought to go to to a at least few more decimal places. We can agree on this. Or not.
Its a matter of whether the person making the measurements knows what he is doing and whether the equipment needed is available. If you want to know how an amplifier will sound look at these things:
Distortion vs frequency; for best results it will not rise
Distortion spectra at 1 Watt
Distortion spectra at -6dB of full power. This particular measurement is where SETs fall on their collective faces as this is where the higher ordered harmonics show up, causing the amp to sound 'dynamic'.
In the case of the distortion spectra the lower orders must always be of enough amplitude to mask the higher orders regardless of the overall amount of distortion. THD as a measurement usually tells you almost nothing and is a good example of Daniel Von Recklinghausen's famous comment.
I would also point out that the transition from most tube amps to Class D amps is probably more challenging for owners than most. Most speakers that sound good to someone with a tube amp will sound different with most Class D amps. As they would with most SS amps that also tend to have much lower output impedance and are also capable of driving more speakers well. Given that, I still suspect most tube amp lovers will be more pleased moving to a good quality modern Class D amp than others. But still in many cases, a move from tube amp to SS amp is also likely to involve a speaker change unless the listener is able to make the adjustment. I suspect many cannot.
Perhaps the Atmasphere Class D amp, coming from a vendor known for their OTL tube amps, is a more natural path to Class D for tube amp owners? One that is less likely to make owners jump ship on speakers they selected to sound good with their prior OTL amps? That would make sense. Just guessing though...have not done the homework yet on the Atmasphere Class D.
In any case, it is not possible to properly assess any amp without also considering the speakers it will be driving. The best amp/speaker integrations will ALWAYS produce the best results. Nothing else is possible, though some amps will care less about what speakers are used than others.
I would also point out that the transition from most tube amps to Class D amps is probably more challenging for owners than most. Most speakers that sound good to someone with a tube amp will sound different with most Class D amps.
Most loudspeakers are meant to be driven by a voltage source which is an amplifier that either doubles power as the load impedance is halved or cuts power in half as the impedance is doubled (tubes, if acting as a voltage source, do the latter and this does depend a bit on which tap is used on the output transformer).
A small number of speakers, but significant in high end audio, are meant to be driven by amps that behave more as a power source rather than voltage source (SETs are an example). The most likely embodiment of this is a tube amp that runs little or no feedback. Some of these speakers have level adjustments (meant to allow the speaker to be adjustable to the voltage response of the amplifier) on the back, like my Classic Audio Loudspeakers. If these adjustments are present they will have to be set up correctly but the speaker will accommodate both types of amps. Another example of this is the Sound Lab electrostatic.
A lawyer might ask, in a court of law, ’which is it? Were you lying then or are you lying now?’ 😁 I’m not suggesting that you’re lying; I am suggesting that its impossible to be truly objective.
Subjective opinions can carry quite a bit of factual information. If all those opinions say the same thing and the people producing them are unaware of each other they carry quite a bit of weight. It seems to me that you’ve still not made the connection of how important measurements are to the subjective experience (and I see that all the time on the subjectivist side as well...). The rules of human hearing are the reason why; as I pointed out earlier all humans use the same perceptual rules. So if we can sort out what’s important to the ear, then we can make the measurements to show if we’ve made progress. The former is the tricky bit!
If you believe that there is factual subjective information contained in the measurements, then wouldn't that be reason enough to publish them?
I don't believe that the subjective opinions of others carry factual information for 3rd parties- that is the nature of subjective opinion by definition- they are feelings or thoughts based on perceptions. Opinion are not facts.
You can amalgamate opinions of a group and develop a model of group tendencies and use it to predict consumer behavior, the basis of market research. But that will never tell you with any real certainty if Random Joe will like your hot sauce. I don’t buy based on market research- I try for myself. And I know many people that aren’t going to pay $5000 for an amp because a group of people on an audio forum says its s’wonderful! They will want to hear it for themselves in their system, in their space. I also know many people who wouldn’t even consider an amp at $5000 without seeing the measurements first.
Yes, you have previously mentioned Fletcher-Munson curves and other such models of aural perception. I have made the point that all of these models you bring up are empirically derived from testing. As a result, their predictive power is only as good as their assumptions and test subjects. I have made mention of the fact that the Fletcher-Munson tests were based on subjects described as young subjects without hearing deficiencies- not really representative of this forum’s members. Also, as empirically based models, they are predictive of group tendencies as they are constructed around average responses from a sample. In other words, they have weak predictive power for any random individual. Again, as I mentioned earlier- for a manufacturer trying to reach a large target market, these models are useful. On the other hand, for an individual user, they are not going to tell you anything with any real certainty. I have made this point on numerous occasions but have yet to see you address it.
All opinions don’t say the same thing- how do they carry "weight"? What "weight"? In whose opinion? Opinions about products are all over the map- that is proven here every day. It is also proven by a market full of successful amps of every sort of class, type, and performance level. There is no one clear winner- there are many successful products which cater to different market segments- tubes/class d, vinyl/digital, cables matter/cables don’t matter.
What’s important to the ear? The ear is just a transducer sending a signal to the brain. It’s how the brain interprets the data that matters. Science tells us we don’t all interpret our perceptions in identical ways- there is variation based on numerous factors. No model is perfect. After all, the Fletcher-Munson curves have been revised repeated over the years.
No, I beg to differ as to the value of other’s subjective opinions when it comes making individual choices and the value of your claims regarding the predictive power of perceptive models on an individual level. Look no further than the marketplace.
You are aware no-one is going to beat Bruno’s numbers any time soon. For that reason alone I really don’t see what you are so concerned about what measurements we get.
Why would your measurements need "to beat Bruno’s numbers" in order to be of value to a potential customer? You claim there is a strong link between the measurements and subjective performance- so why not show how exactly?
Yours is a GaN amp and I presume you chose GaN fets for a reason. I would think you could demonstrate through your product’s measured performance exactly what advantages your product has as a result. You keep talking about distortion spectra and subjective perception of sound. I, and I am sure others, would find these measurements of your amp informative. It’s a competitive market place with many options available to consumers looking for state of the art amplifiers. Clearly you aren’t trying to compete on price, nor does it seem you are attempting to compete on objective performance. I can only assume that you are competing on subjective performance.
In any case, it is not possible to properly assess any amp without also considering the speakers it will be driving. The best amp/speaker integrations will ALWAYS produce the best results. Nothing else is possible, though some amps will care less about what speakers are used than others.
And by extension, the space the equipment will be used in. With state of the art class d amps, the dominant barrier to accurate sound reproduction is the speaker and speaker/room interaction, no long the amp.
When I find out that there is a switching amp that thrills listeners whom I trust, I will be glad to audition one. History has shown that switching amps can ace measurement testing and bore the death out of the listener. No meat to the bones. No there there.
Any amp class can ace measurements and bore the death out of a listener. This is hardly unique to class d amps. Apparently the Benchmark mentioned above didn't excite every listener either, and it's not a class d amp, by the way.
We all know that numbers often don’t tell the story of how something will sound
and yet the designer of the amp under discussion has said this:
Subjective opinions can carry quite a bit of factual information. If all those opinions say the same thing and the people producing them are unaware of each other they carry quite a bit of weight. It seems to me that you've still not made the connection of how important measurements are to the subjective experience (and I see that all the time on the subjectivist side as well...). The rules of human hearing are the reason why; as I pointed out earlier all humans use the same perceptual rules. So if we can sort out what's important to the ear, then we can make the measurements to show if we've made progress.
The AHB2 is a linear amplifier that surpasses the sonic purity of all class-A amplifiers. No amplifier delivers lower noise or lower distortion. The small, passively cooled chassis, cleanly delivers 480 Watts bridged mono into 6 Ohms, with additional reserves for driving difficult speaker loads. Unlike power-hungry class-A amplifiers, the AHB2 achieves a power efficiency that rivals that of a Class D (switching) power amplifier.
The feed-forward design even makes the more efficient Class H or G operation possible — with no rise in distortion at class H or G switch point (Class H, or G, rail switching at a 1/3 power threshold);
What's important to the ear? The ear is just a transducer sending a signal to the brain. It's how the brain interprets the data that matters. Science tells us we don't all interpret our perceptions in identical ways- there is variation based on numerous factors. No model is perfect. After all, the Fletcher-Munson curves have been revised repeated over the years.
The ear is not a simple passive transducer. The brain actually sends signals. Back to the ear.
But that will never tell you with any real certainty if Random Joe will like your hot sauce. I don't buy based on market research- I try for myself. And I know many people that aren't going to pay $5000 for an amp because a group of people on an audio forum says its s'wonderful! They will want to hear it for themselves in their system, in their space. I also know many people who wouldn't even consider an amp at $5000 without seeing the measurements first.
Random Joe's taste in food is something quite different from his ability to taste- to detect flavor (and withstand a hotter sauce 😁). If you conflate the senses vs taste in the audio realm then the art of audio becomes impossible! Its not just Fletcher Munson- I chose that one because its so well-known that there is a switch for it (the 'loudness' switch) on many products. But there are other rules- here's one (easily proven by anyone with simple test equipment): the higher ordered harmonics are used by the ear to sense sound pressure. That one is ignored by the industry most of the time (which is IMO why there is so much stuff that is harsh and bright)... The masking principle is what made MP3s possible. While there are minor variations from individual to individual, these rules are shared by all people with hearing and they are far more alike than different! If you doubt that then all audiologists are just so many charlatans 🤣
The fact that you have to try it for yourself is understandable. As audiophiles quite literally because of limitations in measurement and how spec sheets are designed going back 70 years, despite whatever anyone has said about a product be it audiophile, reviewer, dealer or manufacturer, if his lips are moving he's lying. We've all experienced this so often in the audio world that we don't even think about it- we just have to get the product home to find out no matter what the spec sheet says.
We've had the ability for the spec sheets to really show what the equipment is going to sound like for some time. But it appears the industry would go into conniptions if they actually printed the evidence of why their gear sucks so much! (FWIW Bruno's efforts cannot be quantified since he doesn't sell a finished product. You only get to hear what someone has done with it and that isn't always good... so much for the amazing specs...)
So we still have to audition it at home and make up our own minds. Pretty well defeats the purpose of showing all those measurements, even for someone like yourself! By going with 'measurements only' you are open to confirmation bias. If you really want to be objective you have to drop the measurements thing. Sounds oxymoronic but this is the world we live in today...
Pretty well defeats the purpose of showing all those measurements, even for someone like yourself!
I disagree- there is much more to be learned from a full suite of measurements than simply how something "might" sound.
While there are minor variations from individual to individual, these rules are shared by all people with hearing and they are far more alike than different
We still have no way to accurately predict what an outcome will be for a randomly chosen individual listening to reproduced music- will he prefer a tube amp or class d? Again, the fact that there are successful class d amps and tube amps is proof that there is no consensus subjective choice.
If you believe measurements can indicate subjective sound qualities, publish your measurements and show us how. Show how the GaN fet is an advantage with numbers.
I'm guessing that "kuribo" is the same person who repeatedly posted very similar comments on another online audio forum using the name "goryu." That discussion was focused on comparing the sonic differences between Ncore modules and Purifi modules. The poster in question stated over and over that personal opinions about sound quality are meaningless. Naturally, statements like that are consistently effective in pushing audiophile "buttons."
This guy is just messing you guys. He appears to hold a grudge. A cursory look at his posts (which is all I can bear to do) shows he is talking in circles and sometimes contradicts himself. He's gotten better at covering his mistakes but in the end, he's just messing with you guys, trying to show how bright he is, which I think, is his main objective.
All the best,
Nonoise
Perhaps you’re right, but judging other people motivations is usually fraught with some danger.
And if we assume that he is genuine, then his request for metrics seems appropriate in the context of the amp.
You are aware no-one is going to beat Bruno's numbers any time soon. For that reason alone I really don't see what you are so concerned about what measurements we get. If that is the only concern just buy a Purifi and be done with it. The problem I see with that I already outlined.
…
I am sort of surprised to read ^this^…
I find the noise floor more distressing than the harmonic distortion. So the graphs could possibly add some insight.
Call it Class A-G if it makes you happy but at it's core, the Benchmark was based on a switching power supply which is why it weighs 12.5 lbs.
From S'Phile's coverage of RMAF 2013;
The Benchmark AHB2 amplifier, named in honor of the company's founder, Allen H. Burdick, who passed away just before the show, has a dynamic range claimed to approach 130dB, and outputs 100Wpc into 8 ohms, 170Wpc into 4 ohms and can be bridge to produce 340W into 8 ohms. THD+noise is said to be <–108dB relative to full output at 1kHz. John Siau explained that the THX modules are operated in a mode that gave the lowest noise and distortion rather than the maximum efficiency I wrote about in 2012. A key to the low THD is the use of 0.01%-tolerance resistors at critical points in the circuit. A switching power supply is used, Siau feeling that this was optimal because all the power-supply spuriae will be out-of-band and therefore more readily filtered.
Ralph-would you be willing to discuss your Class D amp in terms of being true balanced (or not)? Please explain the circuit topology in terms of inputting and amplifying the input signal fully true balanced throughout. And assuming it does not, isn't this a compromise?
This guy is just messing you guys. He appears to hold a grudge. A cursory look at his posts (which is all I can bear to do) shows he is talking in circles and sometimes contradicts himself. He's gotten better at covering his mistakes but in the end, he's just messing with you guys, trying to show how bright he is, which I think, is his main objective.
Assuming that once again you are belittling me with unfounded, unproven, baseless accusations, I can't help but wonder exactly what sort of grudge it is I hold and against who and what proof of any of this nonsense you care to share?
You know, in darkness, it doesn't take much of a light to appear bright...
I find the noise floor more distressing than the harmonic distortion. So the graphs could possibly add some insight.
There is a great deal of measurements that could add insight:
1. Distortion versus frequency: flat or rising?
2. Frequency response vs load: independent or dependent?
3. FFT vs frequency: level of even, odd, 2nd, 3rd, later harmonics?
4. Distortion + Noise versus power for different loads: increasing or decreasing? Level?
5. Power stage efficiency vs power at different loads: comparison between GaN and regular mosfets
With people making claims of this amp’s superiority, I see no issue with asking for some proof. When the manufacturer states that there is a lot about an amp’s subjective performance that can be gleaned from the measurements, I say please show us. I just find it hard to understand why the manufacturer makes the claim that measurements contain a great deal of information on the subjective performance yet won't publish said measurements. Especially at the price point. These are not unreasonable requests- plenty of other manufacturers publish this data. What’s the big deal? Why the angst and accusations of some nefarious ulterior motive?
see info below -- what is interesting about this troll is the user account dates back to 2000... so i am not sure it is a ’kid’ we are talking about - or perhaps the original user account was hacked... the writing seems alot like the infamous persistent troll that has used various usernames of late such as dannad, cindyment, deludedaudiophile, but perhaps it is someone different... 347 forum posts ’since 2000’ but over 300 of them in the last 90 days -- anyhow, i am sure the mods are monitoring...and hopefully they will take some action
A rather disappointing reflection on some of the regulars here who if they continue in their childishness the mods will likely delete this entire thread.
Personal attacks, insults, name calling, profanity: the last rhetorical refuge of those who have run out of ammo and are throwing the empty gun in desperation.
The moderators are indeed watching this thread. I expect there will be some action taken over the doxxing, profanity, personal attacks, name calling, and other despicable behavior here. Sad and pathetic.
A rather disappointing reflection on some of the regulars here who if they continue in their childishness the mods will likely delete this entire thread.
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