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

[rdenney]

When measurements suggests differences are inaudible, then hearing no differences requires no special proof. But it is still an uncontrolled subjective observation.

But when one claims that differences are audible (no, not merely audible, because the claim is usually that the difference is obvious, and that anyone should be able to hear it), against the evidence of measurements, there is an obligation to demonstrate that the perceived difference is repeatable and transferable, when not based on the knowledge of what is playing.

If those perceptions hold up to blind testing, the measurable reasons for them can be offered. I offered one such.

Rick “not arguing that amps operating linearly are distinguishable, but wondering how reliable that assumption is in loud listening during tests” Denney

 

[paulraphael]

I would have added a bit of DSP, just to be sure...

He started doing these challenges in the 1990s, so not sure if that would have been such an easy option.

And there might have been some rhetorical value in showing that the only audible difference between this exotic amp and that cheap one can be neutralized with a $3 part from radio shack!

 

[Gorgonzola]

Genuine question - are you serious? Seems to me most anyone would be seriously biased in favor of earning 10 large for an hour's work. Yet the post referred to shows that thousands of people have tried and failed. If only they'd realized they should listen more carefully! Why on earth didn't they think of that?

So I've heard neither you Accuphase nor your Crown amp so I must allow the possibility that they sound very similar.

Accuphase products are beautiful both in appearance and construction but they have always seem like sucker bait to me in terms of sound quality -- more fool you if you bought yours expecting SQ commensurate with price.. I've come that conclusion regarding Pass Labs equipment too, having owned on for a few years.

It's just reasonable to suspect that "confirmation bias" for hardcore objectivists is to hear no differences between amps.

 

[boXem]

And there might have been some rhetorical value in showing that the only audible difference between this exotic amp and that cheap one can be neutralized with a $3 part from radio shack!

Then it's politics, not science.

 

[Katji]

Subjectivist audiophiles' SQ opinions are dismissed on the basis the they are confirmation bias. How is that objectivists, (apparently including mastering engineers), may be assumed to be without bias? Perhaps they hear no differences because hearing none confirms their biases.

Not assumed to be without bias. Hence the insistence on tests being as objective as practically possible. I doubt that mastering egineers are assumed to be unbiased.
PS note: I dislike the "subjectivist"/"objectivist" thing, I only use them for the sake of communication.

 

[Katji]

My personal conclusion:

1. Class D amplifiers have improved a lot of the years but Class D Amps are still no match to good design Class AB Amp.in term of sound quality and dynamic handling

That appears to be on the basis of your experience of that one Class D amplifier. [?]

Problem with human communication and internet. It leads to persistence of outdated ideas about Class D.

 

[Inner Space]

So I've heard neither you Accuphase nor your Crown amp so I must allow the possibility that they sound very similar.

Accuphase products are beautiful both in appearance and construction but they have always seem like sucker bait to me in terms of sound quality -- more fool you if you bought yours expecting SQ commensurate with price.. I've come that conclusion regarding Pass Labs equipment too, having owned on for a few years.

It's just reasonable to suspect that "confirmation bias" for hardcore objectivists is to hear no differences between amps.

You got me mixed up with someone else - I don't have Accuphase or Crown. I use Benchmarks everywhere, apart from a Luxman integrated in one "nostalgia" room, because I always wanted one as a kid.

But yeah, I take your point about bias against. But I guess with enough sample size both hardcore extremes will show up as outliers.

 

[pierre]

No, I wasn't trolling. Subjectivist audiophiles' SQ opinions are dismissed on the basis the they are confirmation bias. How is that objectivists, (apparently including mastering engineers), may be assumed to be without bias? Perhaps they hear no differences because hearing none confirms their biases.

You are the one with the extraordinary claims. Prove them please.

 

[anphex]

That appears to be on the basis of your experience of that one Class D amplifier. [?]

Problem with human communication and internet. It leads to persistence of outdated ideas about Class D.

I guess the problem also seems to be that class d is more difficult to handle then traditional amps to reach reference performance and there is a wider room for error in the design. There are probably more different Class D layouts considering all integrated devices than there are A or AB. But to be honest, if I hadn't upgraded my speakers further while testing the other high end class D amp to this day I wouldn't have noticed the difference. So this whole topic has become really high end nowadays compared to the earlier days of class d.

 

[audio2design]

Adding a capacitor anywhere (either series or parallel) over speaker leads is only going to handicap one amplifier with respect to the other. It'll either act as an HPF (series- high value) or a LPF (parallel- low value).

EQ'ing out frequency response anomalies makes the entire "test" useless. So, he made the amplifiers sound the same, excludes the amplifiers with residual noise (all of them), handicaps the powerful ones and wonders why nobody can claim the prize in his stacked 2x12 correct ABX challenge?

I think you are missing the point.

Intentional changes to the frequency response are going to make noticeable differences. That this could be done with pennies of parts versus $1,000's at retail should be something one would note.

W.R.T. residual noise, at normal listening differences, with most speakers, there is no evident residual noise, and under listening tests, masked. However, some amplifiers have excessive noise making their signature instantly noticeable. It is not part of their sound, it is a recognizable flaw.

W.R.T. handicapping the powerful ones, we are talking again, not about a sonic signature, but capability and it is not nearly as many db as one may expect. There is costs to watts, but it is not that high.

The test is to prove a point, that with the exception of noticeable "flaws", i.e. noise, and intentional or unintentional deviations from flat, all of which can be fixed inexpensively, then when not pushed into clipping, that all these amplifiers sound the same.

 

[audio2design]

Pink noise. Surely, we can all agree it is a reasonable and representative environmental/stimulus sound, not terribly artificial (been to a surf beach lately?) or diabolically dangerous to HiFi gear.

Use it for comparing anything you like, particularly amplifiers in A-B comparisons.

Nope, it is not a good stimulus for volume levelling because it is highly biased to bass frequencies which is where response issues are most likely to become evident due to amplifier impedance and speaker matching.

 

[SIY]

You are the one with the extraordinary claims. Prove them please.

Russell’s Teapot is rampant.

40+ years of claims. Zero evidence. If it were me, I’d be embarrassed.

 

[audio2design]

No, I wasn't trolling. Subjectivist audiophiles' SQ opinions are dismissed on the basis the they are confirmation bias. How is that objectivists, (apparently including mastering engineers), may be assumed to be without bias? Perhaps they hear no differences because hearing none confirms their biases.

Well that is why when a so called subjectivist makes a claim, usually about something like cable or fuse direction, I state quite clearly that we don't need a big test to disprove the claim, we only need a small one, with one person, the person making the claim, to disprove the claim.

However, this is why people who work in audio sciences don't publish studies with 1 listener, but with a larger group of listeners usually with as broad a listener panel as possible. It is also why when I am doing tests personally, I will throw in things that should be noticeable to keep me on my toes. Of course, I also have the ability to create test signals that create well defined issues to train myself, something that self identified subjectivists never do.

 

[Koeitje]

Thanks for sharing.
Curious if you could try playing or streaming SACD Telarc Tchaikovsky 1812 overture and share your experience?
Level match or crank them louder so the contrast is more audible.

Sorry, I prefer not to smoke the small woofers in my speakers

Also the discussion about class D here makes no sense. There are huge differences between different class D amplifiers. Same for class A and AB. I've seen class A amplifiers that are utter garbage, but I don't use those as proof dat alle class A sucks.

 

[mocenigo]

So much handwaving to avoid basic controls.

No handwaving, and I do not want to avoid controlled tests. I am ready to do them, why not, I have already done blind tests (and I never heard differences between DACs that I thought I was hearing sighted!). No need to be sour-sounding. Maybe you need a nice bowl of strawberries? Cheer up!

 

[Matias]

Sorry, I prefer not to smoke the small woofers in my speakers

Also the discussion about class D here makes no sense. There are huge differences between different class D amplifiers. Same for class A and AB. I've seen class A amplifiers that are utter garbage, but I don't use those as proof dat alle class A sucks.

Exactly, there are garbage amplifiers of all classes. I always dismiss opinions that generalize like "all class X sound like this". One has to compare apples to apples, like a high end offering of each class, to really know what the state of the art of a given class sounds like. Which is what the OP did and which is why it was such a great test.

 

[SIY]

No handwaving, and I do not want to avoid controlled tests. I am ready to do them, why not, I have already done blind tests (and I never heard differences between DACs that I thought I was hearing sighted!). No need to be sour-sounding. Maybe you need a nice bowl of strawberries? Cheer up!

True, you did come right out and admit “I am sharing point of views and experiences which are clearly described as sighted and not controlled.”

 

[paulraphael]

Then it's politics, not science.

Why? The cheap capacitor serves the same purpose as a more elaborate DSP in this case. The evidence proves it ... no one could hear the difference. If the capacitor weren't adequate, then Clark wouldn't have trusted it, or he would lost some big bets.

 

[Gorgonzola]

No, I wasn't trolling. Subjectivist audiophiles' SQ opinions are dismissed on the basis the they are confirmation bias. How is that objectivists, (apparently including mastering engineers), may be assumed to be without bias? Perhaps they hear no differences because hearing none confirms their biases.

You are the one with the extraordinary claims. Prove them please.

Let's be clear: I was talking about what we hear, not about measurements or controlled testing.

In truth I don't know whether I could reliably distinguish, say, my Pass amp from my VTV in the usual type of ABX testing. But sitting through hours of listening my ears hear differences. If confirmation bias means you "hear" what you "see", how come that isn't always to the case? Why didn't I hear my $5500 Pass as better than my $1500 Purifi? What a mystery!?!

No more discussion from me on this thread: clearly I'm just hollering down a well.

 

[SIY]

Let's be clear: I was talking about what we hear, not about measurements or controlled testing.

In truth I don't know whether I could reliably distinguish, say, my Pass amp from my VTV in the usual type of ABX testing. But sitting through hours of listening my ears hear differences. If confirmation bias means you "hear" what you "see", how come that isn't always to the case? Why didn't I hear my $5500 Pass as better than my $1500 Purifi? What a mystery!?!

No more discussion from me on this thread: clearly I'm just hollering down a well.

No, what you’re doing is making highly dubious claims and providing zero evidence.