Benchmark AHB2 / Class D Purifi Eigentakt / Mark Levinson 333 - Listening impression & Conclusion

[Touchstone]

... followed by a horribly inapt analogy ...

Oh, I don't know, SIY, maybe all those marvellous things that subjectivists hear are just quantum events that need investigation at that level.

 

[Wes]

I already did twice, along with a handful of other people, with very consistent results. In this case I find it most likely to be the 'fault' of the pascal, as its specs are good, but far less ideal than the purifi - though I don't know. That was the reason for me making that thread: trying to figure out what might cause an audible difference so notable that multiple people in multiple systems/rooms described the same differences, without communicating.

But I've been down this road, I don't expect to change anyone's mind. I know there are people who firmly refuse to entertain anything that doesn't alight with their views. I'm just here to have a casual conversation about the matter, sharing ideas/possible explanations, not to prove anything on an academic level, because I don't currently have the necessary equipment to do that.

It's good to hear that you did blind tests twice. Would you please describe your methodology? Also, what were the results? i.e. x correct out of y comparisons

 

[Lord Victor]

Oh, I don't know, SIY, maybe all those marvellous things that subjectivists hear are just quantum events that need investigation at that level.

So far it seems it was just good old nonlinear THD+N and some impedance interaction. In my case anyway.

 

[SIY]

So far it seems it was just good old nonlinear THD+N and some impedance interaction. In my case anyway.

Or the other possibility you didn't bother to eliminate.

 

[Lord Victor]

Terrible excuse to avoid basic controls, followed by a horribly inapt analogy, with a straw man thrown in at the end for good measure.

If you have no curiosity about what’s real and what isn’t, a science site is not the best place for you to be. If you are, do an actual experiment.

Could say the same for someone who seems to spend all their energy harassing people they disagree with, without actually offering any meaningful points for correction or improvement, hence discouraging any hope “science”.

Whilst I agree where he is going there is rather off the deep end for my tastes as well, there is nothing but high blood pressure to be gained from petty insults and mockery. If someone is going astray, show them the way - and preferably in as clear and concise detail as possible, not just a vapid brush off retort that is unlikely to teach anyone anything that could mitigate future failures, that you’ll inevitably have to spend more time mocking.

if you just find enjoyment in mocking people, I guess it is what it is. But I genuinely hope we could actually work towards something useful or insightful here. That sort of the point if you ask me.

Anyway, I’ll leave it at that before this gets any more sour than it is - just makes everyone look bad.
Until I have the chance to do further, more rigorous testing with these amps, to see if those measurements fit the bill, or wether there was nothing really there, I don’t think I have anymore to contribute here.
Hopefully the OP finds some civil solution or answer to his conundrum, if it is indeed there.

 

[SIY]

Could say the same for someone who seems to spend all their energy harassing people they disagree with, without actually offering any meaningful points for correction or improvement, hence discouraging any hope “science”.

I told you exactly what you need to do in order to honestly make extraordinary claims about "amplifier sound": controls. Basic controls. Ears-only.

"If you can hear it without peeking, you can hear it. If you have to peek to hear it, you can't hear it."

Would you like me to set up a test for you? Results in public?

 

[Wes]

Could say the same for someone who seems to spend all their energy harassing people they disagree with, without actually offering any meaningful points for correction or improvement, hence discouraging any hope “science”.

Whilst I agree where he is going there is rather off the deep end for my tastes as well, there is nothing but high blood pressure to be gained from petty insults and mockery. If someone is going astray, show them the way - and preferably in as clear and concise detail as possible, not just a vapid brush off retort that is unlikely to teach anyone anything that could mitigate future failures, that you’ll inevitably have to spend more time mocking.

if you just find enjoyment in mocking people, I guess it is what it is. But I genuinely hope we could actually work towards something useful or insightful here. That sort of the point if you ask me.

Anyway, I’ll leave it at that before this gets any more sour than it is - just makes everyone look bad.
Until I have the chance to do further, more rigorous testing with these amps, to see if those measurements fit the bill, or wether there was nothing really there, I don’t think I have anymore to contribute here.
Hopefully the OP finds some civil solution or answer to his conundrum, if it is indeed there.

I'm not sure you understand what science is, or requires. Testing is how you actually "actually work towards something useful"

You could have said "Besides confirmation bias, this could also be due to old fashioned nonlinear THD+N and/or some impedance interaction - we would have to eliminate variables to find out."

But you didn't. So the dog has his teeth in your azz and is unlikely to let go until you face facts.

 

[Phorize]

I'm not sure you understand what science is, or requires. Testing is how you actually "actually work towards something useful"

You could have said "Besides confirmation bias, this could also be due to old fashioned nonlinear THD+N and/or some impedance interaction - we would have to eliminate variables to find out."

But you didn't. So the dog has his teeth in your azz and is unlikely to let go until you face facts.

In fairness @Lord Victor has said that he’s attempted controlled tests but he feels he hasn’t identified a protocol that is accepted here. I’m not aware of a consensus on ‘best protocol’ but if there is one it feels relevant now

 

[Phorize]

Just to lighten the mood I also want to point out a that a 47 year old calling himself Phorize has just referred to another adult who goes by the name of Lord Victor. It that can’t cure us of pomposity there’s no hope

 

[Phorize]

Me too...we need new measurement that explains what we heard

Hate to be that guy but you haven’t established that you have heard anything yet. If under controlled conditions you boil this down to the amplifier, then it’s worth investigating further. Again though, bearing in mind the tolerances we are talking about with amplifiers versus what is known to be audible, what reason is there to even suspect the amplifier? The amp has an easy job, take a signal and put gain on it with minimal alteration. It’s when the signal arrives at the mechanical end of the chain that the mayhem starts. Obviously it’s downhill from there...

 

[pogo]

There needs to additional scientific measurements that can explain why the benchmark AHB2 sounds better than Purifi Eigentakt in my environment and why the levinson sounds more dynamic and detailed on loud classical music. Traditional SINAD, THD , IMD measurement using sinewave do not have the musical waverform complexity and can not explain the contrast of what we heard among these amplifiers in our environment. What we heard can not be explained with just THD measurement as they all sound good (not distorted) but different.

These algorithms/tools could also bring you closer to the measurable truth:
Plug-in for Audio Precision Sequence Mode to measure psycho-acoustics parameters

 

[pogo]

A listening comparison between the VTV Purifi Eigentakt EVAL-1 and an NAD M33 would also be interesting, since the NAD designers have made changes to the Purifi input interface compared to the reference design. According to NAD, this should lead to an improved sound, but probably leaves some 'classic' measurements no longer look so good. NAD said, that this deterioration should be in the inaudible range and therefore the improved sound reproduction should remain.

 

[rdenney]

The challenge for manufacturers using Class D modules from a few central providers is that they must still distinguish their products, and for a company like NAD that has always favored minimalist presentation, that can't be the fanciness of the box.

If it were me, I'd focus on cooling, and then brag about what a high percentage of the maximum output I can obtain continuously, using some entertaining and wholly unrealistic tests. Or add distortion that I think makes it sound better with the sort of music most people play.

If I introduced distortion not previously there, I would be up-front about it: "The stock Purifi Eigentakt module is arguable transparent and without distortion. But real listeners find truly transparent amplification to sound dry and thin with many of the recordings they play. The Rickophone Godzillamp uses a custom-designed first-stage amplifier that merges the transparency of the Purifi final-stage amplifier with the music-enhancing richness of sound for which Rickophone has been justifiably famous. Listen for yourself--bring your recordings that have the music you love but that seem to have been mastered to sound dry as dust. We conducted extensive blind testing to demonstrate that listeners prefer the richness of the Rickophone sound to merely transparent amplification. We don't deny our house sound like other companies, we own it."

Then, when Stereophile or ASR measure it, and reveal its slightly audible even-order harmonic distortion, we can say "Yup! But notice that our house sound does not come at the expense of added noise--the noise floor is still at -130 dB just as Purifi designed it, and still produces only 12 uV of output when not playing music--you'll never hear hiss out of the speakers just by turning the Godzillamp on. And, with our silent liquid-cooling, if you play modern compressed pop music at full output for a six-hour party, it's your speakers you'll be worrying about, not the Godzillamp."

These guys should hire me to sling their BS.

Rick "available but not cheap" Denney

 

[Tokyo_John]

The challenge for manufacturers using Class D modules from a few central providers is that they must still distinguish their products...

For me (and perhaps others) there is another simple element at play, although I don't hear it mentioned so much in audiophile forums. My wife understands the difference in power use and efficiency, and on the grounds of energy efficiency, she is put off by the thought of having a Class A or AB amp in the house (headphone amp is one thing, but a larger stereo system is quite another). So we are on a Class D diet. Yes, it is probably a relatively small part of our total electricity budget (depending on the time of year), but it is one thing that we can control (others, like A/C in summer, not so much). Luckily for us, Bruno has given us some brilliant Class D options that make this a small sacrifice.

I still see a lot of hand-waving about what people think a Class D should do to the sound, but not so much (actually, not any) hard data. Differences between amps, all else being equal, are relatively easy to record and compare. Yes, the mic might not be absolutely neutral and calibrated, but the difference between two recorded tracks at similar volume levels will not be very susceptible to such influences. The only question is whether your ear is capable of picking up differences that the recorder cannot...but there are some very good recording setups out there that are relatively affordable, and which should be competitive with the human ear...and should be able to resolve the differences that are discussed here.

 

[pogo]

And this seems to be a measurement method that belongs to the royal class, which could also show a different damping factor well in the swing-out behavior, since the amplitude can be reduced differently over time depending on the DF and can lead to a washed out low frequency range (is also setup dependent and my speakers require a high DF):

3D Step Response Measurement - The sound quality of the reproduction made visible

The 3D Step Response measurement shows the behaviours of the sound reproduction in the non swung-in state. This measurement is very important to judge the reproduction of impulses. As testsignale preferably half sine oscillations of different frequencies at the same time are used, since acoustic events are essentially based on these modes of motion.

The frequency response is totally inadequate for the judgement of sound quality. The frequency response is measured with non-changing (Static) signals such as sine waves or calculated noise signals. Against that, a music signal consists of changing (Dynamic) signals. The study of music signals shows that the sound quality of a musical instrument is determined by impulses. Especially the first impulse, the stroke of a guitar string, the impact of a piano cord, the hit on a drum and the blow of an organ pipe or brass instrument is important for the sound. In the Step-Response, all acoustic parameter information of the sound reproduction is contained. This consists of the frequency response, phase response and swing-in behaviour. There for the display is so complex, that the sound quality judgement based on the measurement is not possible. That is why the 3D Step-Response measurement was developed. By the measurement, the Step-Response is analysed and displayed in a 3D graph. The 3D measurement shows the impulse reproduction for each single frequency with use of an additional frequency axis. The measurement makes it for the first time possible to analyse the sound quality through measurement technology.

(Source: Kirchner elektronik)



Testing is not incorrect in what it measures, but in what it does not measure. You have to swim against the stream to reach its source

 

[Wes]

ask your ENT about sinus waves

it's "sine"

 

[MasterApex]

3D Step Response Measurement - The sound quality of the reproduction made visible
......
The frequency response is totally inadequate for the judgement of sound quality. The frequency response is measured with non-changing (Static) signals such as sine waves or calculated noise signals. Against that, a music signal consists of changing (Dynamic) signals. The study of music signals shows that the sound quality of a musical instrument is determined by impulses. Especially the first impulse, the stroke of a guitar string, the impact of a piano cord, the hit on a drum and the blow of an organ pipe or brass instrument is important for the sound. ....

(Source: Kirchner elektronik)

Testing is not incorrect in what it measures, but in what it does not measure. You have to swim against the stream to reach its source

Thank You
Who does this kind of measurement on amplifiers or speakers?

 

[Kal Rubinson]

ask your ENT about sinus waves

Or your cardiologist, more likely.

it's "sine"

In the US but not everywhere.

 

[audio2design]

The frequency response is totally inadequate for the judgement of sound quality. The frequency response is measured with non-changing (Static) signals such as sine waves or calculated noise signals. Against that, a music signal consists of changing (Dynamic) signals. The study of music signals shows that the sound quality of a musical instrument is determined by impulses. Especially the first impulse, the stroke of a guitar string, the impact of a piano cord, the hit on a drum and the blow of an organ pipe or brass instrument is important for the sound. In the Step-Response, all acoustic parameter information of the sound reproduction is contained. This consists of the frequency response, phase response and swing-in behaviour. There for the display is so complex, that the sound quality judgement based on the measurement is not possible. That is why the 3D Step-Response measurement was developed. By the measurement, the Step-Response is analysed and displayed in a 3D graph. The 3D measurement shows the impulse reproduction for each single frequency with use of an additional frequency axis. The measurement makes it for the first time possible to analyse the sound quality through measurement technology.

(Source: Kirchner elektronik)

Source Kirchner elektronik, supporting evidence, a whole lot of bubkis. The sound quality of an instrument is determined by impulses. I would assume the person who wrote that does not really know what an impulse is, as the attack of most musical instruments is in itself complex and not an "impulse" perse, and it is of course wildly evident that that is just one aspect of how we determine quality of an instrument. With a brass instrument, the concept of an impulse is really going off into fantasy land.

The step response, a square wave essentially, does not exist in nature. That take infinite force, or zero mass. Everything has an acceleration, and beyond that, air acts as a natural low pass filter. There is a reason why real music, even when recorded on wide bandwidth microphones, has little content past 10KHz, let's not even get into what our ears can do. So even if you could create a true step response, no microphone can capture it, no device can record it, no speaker can play it back, no air can transmit it, and ear can hear it. What is left ... other lower frequencies.

Even bringing in phase is a specious argument given our knowledge of how we extract information from sound. Location information using "phase" only exists 200-1500Hz. At all other frequencies, it is loudness.

The 3D step response was mainly developed for speakers to look at settling time, resonances, etc. at a system level.

 

[pogo]

The 3D step response was mainly developed for speakers to look at settling time, resonances, etc. at a system level.

I think, if one modifies this measuring method a little bit, i.e. higher resolution, an optical measuring 'microphone' (laser-based and massless convertion into a electrically signal), like Devialet uses it for more exact measuring results, could be a good beginning. The damping air is omitted in this case.