@atmasphere
Thanks for the comments.
Mine are below...
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.
You wrote:
"In time, the tube amps will be gone. Not because of a lack of tubes but because they’ve been eclipsed and people will wonder why they go through the hassle when subjectively better sound is available at less cost. That hasn’t happened yet simply because class D has taken some terrible missteps in the last 20 years."
Your reply sidesteps my statement, that is, that we can not 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?
Tube amps disappearing because they are a hassle and there will be subjectively superior choices seems a stretch-been hearing that for years. They said that about vinyl. And yet, both are still here and have their rabid supporters. Perhaps they will quit making tubes completely at some point but as long as there are baby boomers and nostalgia, they will survive. And if they do disappear, it will probably encourage someone to make fake tube amps. Wait, someone already is!
You continue to talk about the similarity in how we hear. Yes, the physiology of our senses is similar. The important distinction is that while we all have similar physiology- the transducers that input external stimuli- there are differences in functionality between individuals due to age, slight differences in physiology, etc. This means that while we all "hear" the same, the input to the brain, as empirical studies have shown, is not the exact same- there is a variation. More importantly, while we might all "hear" the same, we don’t all interpret the stimuli in the same way. Research has shown that the interpretation of perceptions is a complex function of experience, mood, and an untold number of biases. Thus, while we all have similar physiology, and "hear" similarly, we don’t all interpret what we hear in the same subjective way. This is proven by the wide range of differing products, each with their own fans. It’s also the reason why there are salt and pepper shakers on tables at restaurants.
You talk about masking of high harmonics. Wouldn’t it be preferable to not have to use 2nd/3rd harmonics to mask higher harmonics? I would prefer an amp that had all the distortion below the threshold of hearing rather than using such a trick to mask them. I suppose that if one were trying to mimic the "sound" of certain tube amps, this could be considered a feature rather than a bug.
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.
You wrote:
"I have stated that some of the above are important parameters to look at. I’ve also stated that our amp has some of those properties. That the distortion does not rise with frequency isn’t something that needs to be shown; its a simple statement of fact (you could have surmised the truth of this by looking at my comments about feedback, Gain Bandwidth Product and of course distortion vs frequency). You either accept it or you don’t- much like you might if you saw a graph on our website- which you might believe or you might not. The bottom line here is trust. You don’t trust other’s opinions since you don’t trust their ears to work the same as yours despite the fact that all ears work the same despite your remonstrations. It is apparent though that you are embrace the subjective experience as anyone else here."
I disagree. You have painted broad strokes and made claims but not delivered on the proof. You are a manufacturer in a hobbyist forum with a self-interest in a product. I believe it reasonable to hold you to a higher standard. When someone is charging 4 times what a market leading product costs, never mind that it has half the output power, I think it unreasonable to just say "trust me". With other manufacturers offering complete measurements I find the "trust" argument woefully insufficient. That is certainly your right but I think it poor form in this venue.
You have mischaracterized my statements regarding my trust of the opinions of others: it has nothing to do with how our ears work and everything to do with differences in perception/taste, never mind the obvious issues of basing anyone’s judgment of an amp in their system and room rather than in my own. Nearly every amp on the market has those who like it, and those who don’t. Why would any rationale person base a $5000 purchase decision on the opinion of someone on an audio forum? No, I don’t value the subjective opinions of others on equipment but I do value my own and would never expect others to place any value in my subjective opinions . In this very thread we have seen negative comments about certain products that have had wide success in the market with many who praise the product.
You wrote:
"Second, you would do yourself well to drop one of two stories about yourself, either that measurements are the only thing to look at, or that you have to try it for yourself. You can’t take both positions at once since others see a contradiction even though you may not see it."
Again, a mischaracterization of my position. Your mistake is claiming I am taking the positions as you have defined them: I have never ever said measurements are the only thing to look at. I have said over and over that measurements offer insight into the engineering, design, and objective performance of an amp, and as such they have value. I use measurements to screen out products that don’t meet my engineering, design/construction, and objective performance standards. From there, those which make the cut get further consideration and audition. I thus use both objective and subjective criteria. I see no contradiction in using both criteria in the purchase decision. In fact, I know many rational people who do the same, whether it is audio equipment, automobiles, computers, etc.
You are not alone in misrepresenting my view. In fact, it seems so commonplace here that I almost have to believe it is being done on purpose in some twisted way to provide a point of attack and the "go back to ASR" smears.
Lastly, I would like to address your comments about Purifi amps and the use of various input buffers to "tailor sound" by several manufacturers. You made a statement to the effect that "if you can hear the opamps, there must be an issue with the design".
First of all, many of these amps, with different opamps, have been tested and while all the results I have seen show that the performance of the amp with these various third party buffer/op amps isn’t quite at the level of the stock Purifi buffer and opamp, the measurements do not show any differences which would normally be considered audible in any way. In other words, if there were some issues with the design, one would expect significant differences.
Reading through the various opinions on these amps, some prefer the Weiss opamp, some the Burson, others Neurochrome, and others have said that the stock Purifi buffer is their choice. Some describe one op amp one way, another describes the same op amp another. Measurements show no differences which can be considered to be audible. They may all be "hearing" the same way, but their brains clearly do not seem to be interpreting the input in the same way. We see this same thing with cables and all the wacky tweak products- none of them can be shown in most cases (poorly designed cables, for example, would be an exception) to do much of anything, yet some people swear they turned their system up to an 11, others say they hear nothing. Previous experiences, mood, biases, go a long way to explain this perception paradox, This is why I find no real value in subjective comments regarding equipment on forums such as this.
Finally, I wish you all the best with your product. You seem to be thoughtful, sincere, and committed to your craft.