I can close my eyes and tell you what something sounds like. Try telling me what they look like on paper with your eyes closed.
I am not sure that is universal.
@holmz Nobody here is saying anyone’s opinion/tastes are universal, but they’re indicative of what one might expect in terms of a product’s sound signature. If any of us have learned anything in this hobby it’s that there is no “universal” truth in music reproduction. But that doesn’t mean one can’t get an INDICATION of what someone might expect out of a component. Case in point, if someone says something sounds warm with somewhat recessed highs that will go a long way to helping someone who may be looking for a highly detailed and more neutral-sounding component. Universal truths are pretty much a myth in this hobby given the myriad of variables involved, not the least of which is each person’s individual preferences and how they hear things. Just my take/experience FWIW.
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I can close my eyes and tell you what something sounds like. Try telling me what they look like on paper with your eyes closed.
I am not sure that is universal.
Both my old and new preamps have very similar harmonic structure, and they have a similar (lack of bad) sound… and the graphs on the reviews look exactly like what Ralph describes.
So just because you cannot hear it looking at the graph, doesn’t mean that Ralph and others can’t.
One negative thing about the ASR testing, is that they only focus on SINAD, and I find a hissing amp to be pretty distressing, and would take some harmonic distortion over hissing. And then there is no weighting, like a discount for 2nd and 3rd harmonic, compared to all/any spray to the right… but the Audio Precision test equipment just kicks out a signal number.
So I do not think that it is out of the question for Kurbio to ask for objective proof. Ralph has been talking about the distribution of the harmonics for a while, so to see it would be dandy way to objectively show some of what makes them sound good..
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@pstores please keep posting as these amplifiers come into their own. Ignore the naysayers and measurement nuts.
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Exactly Charles. I read these threads to find out what people think about how something sounds. Yes that persons opinion. I could care less about what they look like on paper. I can close my eyes and tell you what something sounds like. Try telling me what they look like on paper with your eyes closed.
Pstores please keep the impressions and comparisons coming.
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@pstores
You should continue to post your thoughts and listening impressions as you experience them. This is an open audio topic forum and most folks come here to learn, share and discover. When you come across an excellent sounding product, you want to make others aware. Nothing wrong with that.
I have certainly done the same over the years on this forum. A few examples, Coincident components/speakers, Ocelia cables and Lavricables, Pro-Ject RS2T CD transport etc. I want to share these wonderful discoveries/experiences with fellow music lovers looking for terrific audio products. Audiogon is a great resource.
Charles
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@fsonicsmith
Let me be clear, Ralph never asked me to post anything. I also am a huge fan of Pass Labs, Coincidence, VAC, as well as others. I was very surprised that I really like these Class D’s. As I have posted a long list of others that has been in my system that I didn’t like. And when comparing them in my system with other amps. They exceed my expectations. In fact they have exceeded many peoples expectations that have been to my house. I’ll be posting my impressions of the Aqua LaScala DAC. But I’ll be alittle more careful how I word it. As not to start with what happened in this thread. But I can say…. These amps are very very good. And don’t do anything poorly. They are definitely the best Class D that I’ve had in my system. JMHO
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And this is a truth. I am such a one, for a variety of reasons. I am also careful to consider measurements (defined widely) for a component's attributes, again, for a number of reasons.
Me too @noske - my tube preamp has the 2nd at -75dB the 3rd at -90, and the 5th at -110dB.
My old preamp was predominantly 2nd harmonic.
My latest power amp is not too dissimilar - just a bit higher…
And the older tube amps predated Stereophile’s use of the AP test gear.
So they all look like what Ralph is describing, just we cannot see it.
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@atmasphere
If it walks like a duck and sounds like a duck, it is probably a duck.
From Wiki;
Class-D amplifiers work by generating a train of rectangular pulses of fixed amplitude but varying width and separation, or varying number per unit time, representing the amplitude variations of the analog audio input signal. The modulator clock can synchronize with an incoming digital audio signal, thus removing the necessity to convert the signal to analog. The output of the modulator is then used to gate the output transistors on and off alternately. Great care is taken to ensure that the pair of transistors are never allowed to conduct together, as this would cause a short circuit between the supply rails through the transistors.
So yes, Class D is more accurately referred to as a "switching amplifier" rather than a "digital amplifier" but things get blurred when binary quantization is involved as binary quantization is at the heart of digital too.
I find it interesting that in order to "cut me down to size" you chose to seize upon my bad choice of nomenclature (when I in fact used BOTH within the same paragraph!) rather than comment upon the bigger points made in my post.
I will say it again also-I have no doubt that this is a very fine sounding amp. I would expect nothing less from a man of your immense experience, intellect, and knowledge. I just get my hackles up a bit when someone like our OP posts a sensationalistic thread title and then waxes on and on. You don't want to be equated with Tekton do you?
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@holmz
some might still prefer the signal modified, or distorted, so that the 2nd/3rd harmonics were present.
Some of this may also bleed into people running tube preamps into SS/Class-D amps.
And this is a truth. I am such a one, for a variety of reasons. I am also careful to consider measurements (defined widely) for a component's attributes, again, for a number of reasons.
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@jerryg123
Wow, hadn’t seen this 6moons article! Very cool, thank you 🙏🏼
They really are making some nice stuff.
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Someone, please correct me:
I don't believe that the idea is to "want" 2nd and 3rd harmonic distortion, but rather our brains use the 2nd and 3rd harmonics that are produced by the musical instruments to perceive certain aspects from the sound. I don't believe any type of harmonic distortion from an amplifier is "desirable".
I read Atmasphere’s words as, ‘given the choice between no 2nd/3rd harmonics, then having them allows one to mask the higher order harmonics. So you want them higher than everything at 4th and higher harmonics.
If the higher order harmonics are not there to begin with, then the 2nd/3rd do not need to mask anything… but some might still prefer the signal modified, or distorted, so that the 2nd/3rd harmonics were present.
Some of this may also bleed into people running tube preamps into SS/Class-D amps.
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I don't believe any type of harmonic distortion from an amplifier is "desirable".
Some like the added distortion, others prefer the truth. Personal preference.
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@jerryg123
I had been confused about it initially, as GoldNote does not clearly specify what’s actually going on with the PA10’s internals. But learned this from a HiFiPig review (as quoted):
‘I’m a massive advocate of Class D technology when it is done well and so I asked Gold Note directly “What Class of amplifier is the PA-10?”. Here is the response I got – “ The PA-10 features quite an interesting design. It is not a Class D amplifier but it leverages a new technology that uses MOSFETs for the output stage, in common with the Class D, featuring an output oscillator (GaN Mosfets with Gallium Nitride), a proprietary design that actually doubles the power of the amplifier when reducing the impedance – exactly as a pure Class A but with extremely high efficiency to deliver great amounts of energy.” So there you have it.‘
So “more like” GaN Fet in output.
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Embrace the 2nd and 3rd harmonic distortion at low levels is the message. If you don’t like the message then move on.
Someone, please correct me:
I don't believe that the idea is to "want" 2nd and 3rd harmonic distortion, but rather our brains use the 2nd and 3rd harmonics that are produced by the musical instruments to perceive certain aspects from the sound. I don't believe any type of harmonic distortion from an amplifier is "desirable".
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@riccitone the Goldnote PA-10 is simply A-D not GaN I had them at one point.
not sure what Core they are using. I might be wrong.
The PA-10 is a 200x80x260mm (WHD) Class A/D hybrid power amplifier. In stereo mode, it’s specified at 75wpc into 8Ω (150wpc into 4Ω, 300wpc into 2Ω). Enough for average-to-high sensitivity loudspeakers.
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Someday would love to try a set of these! But got to say, pretty solidly in love with my current GoldNote PA-10 (class A into GaN power stage). But truth and proof in class D from here on out.
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Embrace the 2nd and 3rd harmonic distortion at low levels is the message. If you don’t like the message then move on.
Certainly - the message seems to be that the 2nd and 3rd harmonics are better than the hash of 4th + .
I would like to see an example PSD of a 1kHz tone, and the harmonics.
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I am starting to think class D is the bee’s knee’s man. Really enjoying the Rouge Pharaoh II and it is not even near broken in. Tube pre- Class D power section with the Hypex Ncore. Time will tell but I may be selling a couple of integrated amps I have in the tool shed.
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It’s ok to prefer no distortion… think acoustic guitar.
Its ok to prefer some distortion… think electric guitar with tube amp and pedals.
Preferences are just those… no right or wrong
Not worth disputing… not worth debating.
Thanks Ralph for making another great product.
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Embrace the 2nd and 3rd harmonic distortion at low levels is the message. If you don’t like the message then move on.
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Loudspeakers are the number one producer of distortion. Distortion needs to be embraced, not made the focus of elimination
^This^ is total BS.
Fat girls or guys also need to be embraced, but I am not embracing them.
Coincidentally the Purifi drivers are also the lowest distortion drivers.
It is fine if you like high distortion, but don’t claim that high distortion is high fidelity. That sort of BS double talk is a like it is from a character out of Ayn Rand.
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@soix
I knew I’d regret saying something. My bad.
You have keen instincts. Trust them.
Charles
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@facten @soix
i just think it is a shame that one turd can muddy up a nice thread supporting ralph’s new amplifer ...
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Guys continue to spend time endlessly arguing back and forth, go listen to some music
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I knew I’d regret saying something. My bad.
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@soix
There’s obviously much more to good sound than a lack of distortion.
"good" sound is a subjective opinion that depending on the listener, may have something, everything, or nothing to do with distortion or the lack thereof.
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@kuribo You do know we have published specs right?
If you mean a rather thorough and complete set along the lines of Hypex and Purifi, no. Please provide a link if you have time...Thanks.
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There’s obviously much more to good sound than a lack of distortion. Japanese companies tripped all over themselves in the 70s/80s to produce the lowest THD specs and by and large produced amps/receivers that sounded awful.
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And then we come to digital amps as a category. They are insanely cheap to manufacture as has been pointed out elsewhere in this thread. To my mind, a digital amp is a switching power supply built to drive loudspeakers. If there is a simpler way to harness power from the wall directly to the pre-recorded sound signal it has not yet been invented. Ralph has acknowledged that the box-a plain vanilla box at that-is the major parts cost of this product. When the best switching power supplies sound better than the best linear power supplies I will likewise believe that the best digital amps sound better than the best conventional Class A/Class A/B ss and tubed amps.
@fsonicsmith Let's clear something up. Class D isn't digital. It's a coincidence that the D and digital use the same letter. Its called class D because at the time (late 1950s) class A, B and C were already taken. Its an analog process.
It behaves a bit differently from a switching power supply. For one thing the switching frequency is a lot higher- often by an order of magnitude. Another thing to understand is that switching power supplies are often used in class D amps but class D amps can run off of conventional power supplies too. But even in SMPSs the noise floor is much lower now than it was 30 years ago. Like anything else people sort this stuff out over time. FWIW our class D is so quiet that most tube amps inject more noise on the AC line.
@kuribo You do know we have published specs right?
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@fsonicsmith
Here we go again-the old fallacy that the lack of distortion means more faithful sound reproduction.
How would you define/measure faithful sound reproduction?
If the output doesn't match the input, how can the result be called faithful?
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Also, how humans sense sound pressure does not change from individual to individual; generally, the higher ordered harmonics are used. This is really easy to demonstrate using simple test equipment. Imagine a world where every individual used entirely different hearing perceptual rules! It would be a good basis for a scifi novel 😉
@atmasphere
thanks for the reply.
Of course I am not claiming that the "how" is different in every individual. What I am claiming is that there is enough natural variation among humans in reception, processing, and interpretation of external stimuli that one can not predict with certainty how any one individual will respond, all the more so when the amp is but a piece in a complex system full of external and internal variables. Clearly experimental results with a large enough sample can yield tendencies and generalities, but again, nothing that can predict with certainty on an individual basis. From your standpoint, that’s useful. From mine, not so much as I still need to listen for myself.
I am glad to hear that the feedback from your customers has been positive. It’s clear a lot of time, energy, and thought went into your product. I won’t hold my breath waiting for the measurements- you must have your reasons for not publishing them.
It might be interesting to consider that sound itself only exists in the head of the individual. It’s a back and forth from air pressure changes to electric signals. Our ears are transducers changing the air pressure pulses to electric impulses in our head. It is in our mind that these signals are perceived as sound. A lot of links in that chain that can cause differences in how the end result is perceived.
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The OP has not been very clear as to whether Ralph suggested that he post his impressions. Ralph has a new product and he needs to get some attention over it. Even if not, it is pretty abundantly clear that the OP is already a fan of Atma-Sphere and is far from neutral. It is exceedingly rare for someone to go nuts over the sound of an amp. Amps have a subtle affect on overall sound, and there has never been an amp and likely will never be an amp that "bowls one over" immediately with sound from the heavens. I believe that amps are critically important to overall SQ but it takes months of living with an amp to assess it's character and attributes. So despite the silliness in this thread over non-related matters the circumspection is not surprising.
And then we come to digital amps as a category. They are insanely cheap to manufacture as has been pointed out elsewhere in this thread. To my mind, a digital amp is a switching power supply built to drive loudspeakers. If there is a simpler way to harness power from the wall directly to the pre-recorded sound signal it has not yet been invented. Ralph has acknowledged that the box-a plain vanilla box at that-is the major parts cost of this product. When the best switching power supplies sound better than the best linear power supplies I will likewise believe that the best digital amps sound better than the best conventional Class A/Class A/B ss and tubed amps.
Ironically enough, the discussion is still about distortion-that this digital amp has less of it. Here we go again-the old fallacy that the lack of distortion means more faithful sound reproduction. Loudspeakers are the number one producer of distortion. Distortion needs to be embraced, not made the focus of elimination. Even the power in the wall contains distortion. Harnessing raw power from the wall is not the answer. I wish Charles Hansen and Tim De Paravicini were alive to lend their voices to this discussion. I wish Nelson Pass would join.
In summary, I have no doubt this amp sounds fine. Very fine. Just the same, it is bound to have sonic virtues and faults like any other amp. It won't make your grass greener, your hair thicker, or give you greater stamina in the bedroom.
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@wolf_garcia The smaller guitar amps will hang around for a while because they are low enough power that its practical to overdrive them. But the bigger stuff like 100 Watt Marshals are likely threatened, if someone can put a class D amp out there that's worth listening to. The weight is a big variable here.
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I disagree with Ralph about tube guitar amps...they're not going away anytime soon, if ever. Note that serious pro guitar players generally start with a great tube amp in pretty much every case (exceptions for those who run "into the board" with effects...rare and generally sounding sort of processed), and add their personal pedal choices to the tube amp. Duke Levine (local Boston area guitar genius) describes his current rig in Vintage Guitar...he's touring with Bonnie Raitt...VOX AC30...I've known Duke for 20 years and every time I've either worked a show with him or simply seen him play he shows up with some of the coolest tube guitar amps on earth. Same thing with the brilliant Julian Lage...tiny 50's Fender tweeds like a Tweed Champ or some other little tube amp like a Magic. Brilliant sound...and no overdrive pedals for Julian.
I considered Ralph's D monos when I bought my Pass XA-25 but the Ralph amps (that's what they're called, right?) weren't available yet so I had no idea what they were going to cost...now I'm so disturbingly enamored with the Pass amp I'm hard to nudge away from it...I'd still like to hear the Ralphs sometime...maybe a lower powered stereo amp? Loaned to me? heh heh...
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While these rules of thumb are helpful perhaps to people such as yourself designing amplifiers aimed at as broad a segment of the market as possible, they are not "laws" or universally applicable "truths" like the law of conservation of energy or the laws of thermodynamics. As a result, they can not be relied upon on to be an accurate predictor on an individual basis. Thus, the guy shelling out $5K for an amp would be best advised to trust his own perceptions and tastes and to listen to the amp in his system, in his room, to form his opinions rather than rely on the perceptions, tastes, and opinions of others.
Fletcher Munson is a bit more variable, but the masking principle isn't. Its what made MP3s possible. Also, how humans sense sound pressure does not change from individual to individual; generally, the higher ordered harmonics are used. This is really easy to demonstrate using simple test equipment. Imagine a world where every individual used entirely different hearing perceptual rules! It would be a good basis for a scifi novel 😉
The patent involves the use of a Circlotron to reduce deadtime. If you are using GaNFETs, the inductive kick of the output filter coil is what really turns the device off (assuming the gate is already off); to allow that to happen a certain amount of deadtime has to exist. As it is there is still less deadtime in a GaNFET design as opposed to a MOSFET design.
Too many don't understand the difference between their subjective opinions and objective fact.
Being objective is a worthy struggle despite it being impossible.
FWIW we've done lots of comparisons and we have a lot of feedback from the field at this point- from a variety of customers that know our prior work. The feedback is surprisingly consistent, in the face of not knowing about any other feedback we've received.
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@holmz
I would have thought by now my point had been made.
Yes to both your questions.
No harm in using forums to learn of new gear. One needs to read critically and take the subjective opinions with a grain of salt. When it is all subjective opinion there isn’t much sense that can be made of it if you are a rational actor. Too many don't understand the difference between their subjective opinions and objective fact.
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@kuribo generally agree, but what is your point?
- Is it that you want to see specs?
- Or listen to it?
Or what am I missing?
If a bunch of people with speaker-X say that they like electronics-A, B and C, then I think to myself, “I should see if I like them.”
If I do not like speaker-Y and a bunch of people say electronics-C, D, and E are great, then and not sure what I should with that… especially with D and E.
As there are more electronics that one can often stumble across we use other peoples observations and opinions on a forum to make some sense of it, and get exposed to things which we may not find, or otherwise know to look for.
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@holmz
But if we assume that some amps were possible with a vanishingly low THD+N, then they would sound the same regales of topology
There are indeed those who claim once a certain level of performance has been reached, then products would indeed be indistinguishable from one another. I believe there have been rather rigorous tests done which seem to bear this out.
As I said, Fletcher-Munson and other such empirical studies have predictive power in a general sense but are weak on an individual basis. Additionally, personal preferences when it comes to audio gear is not based solely on sound, in any case. There are several other factors buyers consider when making a purchase which factor into a decision. It’s a complex decision that one needs to ultimately make for one’s self in the proper context.
Sure, a person could choose a proxy and take a chance. It all depends on risk tolerance and finding a suitable proxy. Me, I prefer to judge for myself as finding someone else with my tastes, the same gear and acoustical space, would be more difficult, time consuming, and risky than just trying the equipment myself. Besides, even if I associated myself with a "like minded group", the critical issues of component interaction and acoustical interaction in my space would make it impossible to find a realistically "safe" bet.
I don't believe your analogy is appropriate, either for those "cable deniers" who base their argument primarily on an intellectual argument- it's a belief system, not a perception driven matter of taste, nor for those who simply claim that they hear no differences. That is more a pure perception argument rather than a matter of taste. In either case, it isn't a simple matter of taste at work, unlike the debates centered on amps, etc.
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Strictly speaking, Fletcher-Munson and the like are not rules or laws, but rather experimentally derived models of human aural perception. They are built on averages and generalities- in the case of Fletcher-Munson the results are said to apply to "average young people without significant hearing impairment". I doubt that describes many of those reading this thread... They have also been revised numerous times. While these rules of thumb are helpful perhaps to people such as yourself designing amplifiers aimed at as broad a segment of the market as possible, they are not "laws" or universally applicable "truths" like …
In terms of universal truths and laws, one can pretty safely say that as the distortion products go to zero, that the fidelity improves. How well this happens with complex loads, etc. is where topologies matter. But if we assume that some amps were possible with a vanishingly low THD+N, then they would sound the same regales of topology
… the law of conservation of energy or the laws of thermodynamics. As a result, they can not be relied upon on to be an accurate predictor on an individual basis.
Statistics, stereotype and generalities are borne from things being similar.
Humans are tuned to those sorts of easy ways to categorise things.
And the statistics of a group, are indicative if the sum of the individual biases and likes/dislikes.
Thus, the guy shelling out $5K for an amp would be best advised to trust his own perceptions and tastes and to listen to the amp in his system, in his room, to form his opinions rather than rely on the perceptions, tastes, and opinions of others. Of course there are always those who love to gamble.
And thus if one considers themselves similar to others in the group, then they would be more wise to gamble that what other people like, that they will also find that they the same stuff.
and likewise if they find that they are at odds with the group, then they would likely deviate from the group perspective.
An example would be cable deniers or believers.
- If one identifies as a cable believer, then other cable believer perspectives likely have more bearing, and theuy find speaker cables, IC and power cables all matter.
- And for the cable denier, they likely find similarity with other cable deniers, and value their similar group’s inputs.
- and some probably find no difference in XLRs and power cords, but could believe that speaker cables make a difference, and identify with their brethren/sisters.
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@atmasphere
Thank you replying....
There are the rules of human hearing perception (such as Fletcher Munson or the masking principle) and there is taste. They are two very different things and the two get conflated quite often! All humans use the same hearing perceptual rules- otherwise audio as an art would be impossible. What people do with that is different, which is why there is disco, rap, classical, tone controls and the like. Human physiology responds the same way to distortion, so it is something that is predictable and reliable within certain limits (there is individual variance on how the 3rd is perceived, depending on its phase for example).
Strictly speaking, Fletcher-Munson and the like are not rules or laws, but rather experimentally derived models of human aural perception. They are built on averages and generalities- in the case of Fletcher-Munson the results are said to apply to "average young people without significant hearing impairment". I doubt that describes many of those reading this thread... They have also been revised numerous times. While these rules of thumb are helpful perhaps to people such as yourself designing amplifiers aimed at as broad a segment of the market as possible, they are not "laws" or universally applicable "truths" like the law of conservation of energy or the laws of thermodynamics. As a result, they can not be relied upon on to be an accurate predictor on an individual basis. Thus, the guy shelling out $5K for an amp would be best advised to trust his own perceptions and tastes and to listen to the amp in his system, in his room, to form his opinions rather than rely on the perceptions, tastes, and opinions of others. Of course there are always those who love to gamble.
I see that you haven't made any comments addressing the patent that you received related to this amp, nor related why you have yet to publish any measurement plots, etc. Having this on the market now for a while, I would have hoped that info would have been forthcoming. Perhaps the transparency of Hypex and Purifi has spoiled me.
Again, thanks for your time. And best wishes on the success of your product.
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@atmasphere
Really appreciate your insightful experience and comments.
I am thankful that you brought Class D to the market and that it has been so well received. I run Class D myself, though it is not the typical Class D amp - it is the TAD M2500. In the process of choosing an amp, I listened to Luxman, Pass, Burmester (very good), and maybe one or two others, I forget, and the TAD was the best that fell into my budget - only the Burmester 909 with matching 077 preamp was better, but at $$ multiples of the M2500 + C2000 pre. This pairing makes my TAD E-1s sing and I’m sure part of that is system/manufacturer synergy, but if Class D were not good, the system would not be sublime like it is.
I hope the more manufacturers will make high quality Class D amps, glad you’ve beat nearly all of them to the punch.
Thanks again for being the gentlemen and sharing your decades of experience with us all.
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Would you mind reiterating your past comment of how Class D (yours and perhaps others) have finally made the leap to outperform tubes (yours and others)?
I find the class D to be more transparent in my system compared to my tube amps; less coloration also due to lower distortion. At the same time I don't find them harsh, a classic sin of solid state amps in general. I can play them all day and not get tired of them.
Now let's say you are a tube amp producer. You face a variety of problems. Right now a major one is availability. If you're not going to get in trouble with the law (due to sanctions against Russia), you're probably using Chinese or JJ tubes if you're using new tubes. Another one is the industry is tending towards 4 Ohms as the default speaker impedance rather than 8; I see this as a bad thing since all amps make greater distortion into lower impedances, and with many its enough to be heard (audiophiles use 'fat' 'muddy' and other similar expressions for this). But 4 Ohms is a thing regardless of what I think.
Its now possible to build a solid state amp that is as relaxed as a good tube amp, not lacking detail or depth (and maybe more). Since brightness and harshness of solid state is what has kept tube amp producers in business for the last 60 years, and also because tube amplifier power is more expensive, how long will tubes be a viable option in audio? IMO while it will still be a while (owing largely to highly variable results designers got out of class D over the last 20 years having poisoned the well at first) tubes will continue for a while, but even chip-based class D amps that might only be $75.00 are now giving serious tube amps a run for the money!
If I were an amplifier manufacturer that had not got the class D thing figured out, right now I would be worried. The market will be shrinking for tube power products- even in the guitar world. I know a lot of cheap class D guitar amps are so much junk but they aren't all that way, and most guitarists these days rely on their effect pedals for their 'sound'. The guitar market is a lot larger than the high end audio market for tube use- they drive a lot of what is available for high end as a result. If you lose the guitar market, that will be very nearly the end of tubes.
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@atmasphere (Ralph)
As always your explanations and insight are most appreciated and welcome. I agree with your “no accounting for taste “ as this is true. Be it audio components/music genre/food or automobiles etc. as human beings, We like what we like. 😊
Thus the multitude of choices available in our lives,
Charles
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Hi Ralph,
Would you mind reiterating your past comment of how Class D (yours and perhaps others) have finally made the leap to outperform tubes (yours and others)?
thx
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@atmasphere
A nice, "high-road" explanation. Thank you.
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Testing has indicated correlations between certain distortion spectra and "averaged" or group perceptions but there has been no perfect correlation established between measurements and human response on an individual basis because at the end of the day, you just can’t account for taste.
@kuribo
There are the rules of human hearing perception (such as Fletcher Munson or the masking principle) and there is taste. They are two very different things and the two get conflated quite often! All humans use the same hearing perceptual rules- otherwise audio as an art would be impossible. What people do with that is different, which is why there is disco, rap, classical, tone controls and the like. Human physiology responds the same way to distortion, so it is something that is predictable and reliable within certain limits (there is individual variance on how the 3rd is perceived, depending on its phase for example).
I wasn’t aware that class D amplification was doable without the utilization of negative feedback
@charles1dad It is. Our first prototypes were all zero feedback and demonstrated to us that the idea of class D was worth pursuit. You also don’t need opamps- again we drove early prototypes directly using our preamps, which have no trouble driving lower impedances like 2000 Ohms. These prototypes didn’t use any opamps.
You can’t seem to get beyond the simple truth that your experienced subjective reality and beliefs are nothing but opinions and are no more valid than anyone else’s. The guru complex.
+1 AGS, Audiophile Guru Syndrome, is an ugly thing :)
His high feedback Op-amps amplifier versus a near polar /opposite approach is something that I find compelling with regard to respective sonic presentation. All that concerns me with audio products is how do they sound? That’s why we buy them.
The reason for both approaches is the same. IMO/IME the amp must not have any increase in distortion as the test frequency is increased. Most amps using feedback suffer this problem- and they sound brighter and harsher than they should partially on that account. In a tube amp, getting it to run enough feedback to get around this problem is impossible regardless of the topology. This is because they lack the Gain Bandwidth Product to support the feedback at higher frequencies- as you increase frequency, the amp requires a lot of GBP; if its not there the feedback will fall off, causing distortion to rise. We avoided that in our OTLs by running them zero feedback.
This is a problem in solid state too- and is part of why traditional solid state amps are known to sound bright and harsh (especially at higher volume). Class D offers a way around this because you can get the loop gain you need to really support a high GBP value- and thus also support high feedback at all audio frequencies.
The reason feedback can be problematic is that the feedback node always has a non-linearity associated with it. This might be the base of a transistor, or the cathode of a tube; whatever it is means the feedback signal is distorted by that non-linearity and so when mixed with the incoming signal doesn’t quite do what its supposed to do (one effect of this is additional distortion is created...). But if you run enough feedback you start to get around this problem. That needs to be at a minimum 30dB and must be 30dB at all audio frequencies. We’re at about 37dB.
Probably more information than you were expecting, and actually IMO this explanation is really the nutshell version so those of you technically-minded I am aware this explanation is incomplete.
If the desire is for more emotion ,soul, humanity, breathe of life type of sound, a high quality SET or OTL is very difficult to match. It just always depends on what you want. Other topologies will excel in other specific sonic parameters/areas.
I think one of the issues you run into when making this comparison is that the zero feedback tube amps (whether SET or OTL) will have a frequency response variation depending on the load impedance (the speaker). I’ve found that anyone using such equipment, including myself, has made accommodations for that issue if they have spent any time trying to make their system sound neutral and musical at the same time. In my case this is mostly to do with the level settings for the drivers, found on the rear of my speakers. I use pink noise to set them up correctly. Whatever those accommodations are though, you have to back them out of your system if you really want to do a proper comparison, which is probably tricky. This is just a personal observation, but once I corrected my system for the voltage response of the class D I found it every bit as involving.
I would like to hear the designer’s take on how his class d design differs from those of Hypex and Purifi and at 3 to 4 times the price, what they offer over the Hypex and Purifi products that makes them worth the considerable difference. I would like to know why he decided to design his own class d modules, especially in light of the fact that it is no trivial matter and a completely different task than designing a tube amp....I would like to know why the designer choose GaNfets over standard fets and what advantages he believes they offer at his operating frequency over standard fets....
We chose to design our own module because it sends the wrong message to the marketplace by using someone else’s- it suggests that maybe you don’t don’t have the engineering talent in-house. Plus we can make it the way we want to. FWIW our modules seem to be lower noise than Bruno’s.
The reason we’ve not used SMPSs yet is we found that if you really want the amp to perform properly, especially at high volume, the SMPS really needs to be designed specifically for the application. Most of our prototypes ran SMPSs and we ran into this limitation quite frequently.
A good portion of our cost is the chassis, which is custom-built and designed to look decent, not man-cave and also be durable in shipment. It seems its a bit over-built! For the last 40 years we’ve gotten dinged on cosmetics a lot; you put in the cosmetics and then you get dinged on price...
GaNFETs are a little faster, but the main reason for using them is to create a lower noise layout due to less strays and lower drive requirements which are for the most part an order of magnitude lower than MOSFETs. In this regard the noise our amps put out on the AC line is lower than many tube amps and most of that comes from the power rectifiers rather than anything to do with the module.
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@tinear123 Don’t give up now! It is pretty easy to just ignore and not respond when there is no value to the posts. There are plenty of folks left who would value your perspectives.
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