Objectivist or Subjectivist? Give Me a Break

[microstrip]

I am with Ethan, there is a limit to what you can hear, as far as level, in db down, in music.

Tom,
Can you technically quantify this limit? Or is this just a feeling with an undefined level?

 

[jkeny]

Don,

The Carver challenge is part of audio history, but technically it is a undocumented experience, where we must guess most of the facts, and naturally people feel free to interpret it and make their own conclusions. Mine is that Bob Carver is a genius of electronics, and managed to make the two amplifiers sound the same in the conditions the challenge was carried. Whether they sounded similar because of the -70db null effect or anything else that Bod did to the amplifier was never established.

Again IMHO the audio crowds need simple facts and strong evidences to feed their folklore - the Carver challenge seemed adequate for this purpose, specially since it had the benediction of the TAS authorities, no technical documentation, just vague statements, and most of it, an epic formulation.

It's interesting to note in that article (page 4) that even when Bob had finally achieved a 70dB null, there is still an audible difference between the amplifiers. Only when Bob halves the output of his amp below 30Hz that they now sound identical. How was this audible difference possible with a null difference of 70dB?. Is the null only across the mid-band, as has been stated? Is 70dB not a deep enough null? Is the null only dealing with one channel & ignoring differences between channels? All these questions!!

 

[jkeny]

Tube transformers shift phase. Thats a fact. Not a question. 70db is a deep enough null per subjectivists, who claim thier ears are better than measurments.

So what are you saying here, Tom - that the 70dB null was not a guarantee of audible equivalence & tweaks had to be made to the amplifer using his ears. That certainly is the way it's described in the write-up & to me shows that the 70dB is not the full criteria for audible equivalence of two amplifiers. How do you read it?

 

[microstrip]

Micro, you have got to be kidding! The Carver challenge was the ultimate, epic, experiment between objective and subjective. You are a subjective person mostly, and you hear differences between amplifiers and such, and so can I when they are there to be heard. The subjectivist camp said they can hear differences between any two amps, and Carver proved they can not. They admitted it. They are the Golden Ears.

There simply is a point, in this case using a null technique as the ONE measurment, that proved, that subjectivists can not hear the difference between any two amps because audio science is above reproach as it can be manipulated to overrule the ear. It was done. The case was and is proved and closed....what was actually proved is that we human beings have a limit to our hearing ability. I don't understand why that is so hard to grasp by some (I am not saying you) on this forum.

Of course, the Ethan esperiement


"My AES Audio Myths video references hi-res Wave files you can download containing artifacts at various levels below the music. That section starts at 32 minutes in. Please tell us at what level the added artifact noise is no longer audible to you."




is also the same thing in a way, there is a point where in music, you can no longer hear a disruptive signal, there is a limit to hearing. In Ethans test, the only difference is the level of the interferene signal, nothing to do with the entiere system, just the source. THe better your system and ears are, the lower down the signal can be before you can no longer hear it. But you will no longer hear it and so will all the rest of us.

And Ethans experiment is easier, because you can hear the interference signal loud to start with, then go down in level. A more difficult, but accurate test, is to bring the interference signal up from below audibility until you can hear it.

Tom,

As usual you supply nice words, even more subjective than mine. The fact is that you accept that a non technically documented experiment proves and closes something and once asked to supply quantitative and qualitative technical data to support your statement you refer to other people videos, hiding a direct answer behind a demand for the participation of the others.

Anyway, nice to know you consider that an uncontrolled experiment carried in hotel rooms more than 25 years ago using tubed equipment with high measurable distortion is the ultimate, epic, experiment between objective and subjective . We can agree on the eipic, nothing else.

 

[microstrip]

70db is defined, and maybe even less (ie 65 or whatever). Carver defined it in one system, a high end system, hand selected by TAS, as being the best system to reveal music. Maybe if there is a dog around it would be different for him but for the humans with golden ears, it is no more than 70db, and in Ethans test, the ability to identify "distortion" is even less in music.

Tom,
Can you give a straight answer about your quantitative position, without a maybe or whatever? Please consider any recording having a 0dB maximum level.

 

[jkeny]

Tom,
Of course hearing has limitations. But does a simplistic, single measurement define it's limits - I don't believe so! Many here seem so in need of such a single measure that they accept almost any such measurement without question.
Another thing that I wonder about in the reported Carver test - he seems to be able to achieve 70dB null for two different amplifiers but yet can't get better than 36dB null for two of his own production amplifers. Something doesn't seem correct to me with this inconsistency!

 

[treitz3]

Hello, John. Bob had more than enough challenges to do what he did but when it came to production models, his biggest challenge was the BOD who eventually let him go after he sold the company. The BOD was all about profit and many times, what Bob wanted is not what the end result was. I hope this helps to understand at least why this is the case. I have been privy enough to listen to some prototype gear that Carver built. The difference between the production and the prototype can be quite a change.

Tom

 

[JackD201]

Get a grip guys. Carver made his amp sound like the Jadis by mimicking the Jadis' tonal balance using resistors. He had distortion pots but didn't even need to use them. How do I know? He said so and it's on youtube. This is something that could be done by ear just as any instrument can be tuned by ear. That he also used null testing does not make its use the friggin' end all be all.

 

[Ethan Winer]

A very interesting technical paper dealing with null testing of an amp design - http://www-f9.ijs.si/~margan/Articles/Class_B_Dist.pdf

Excellent, that's a keeper, thanks for posting the link.

--Ethan

 

[Ethan Winer]

Can you technically quantify this limit? Or is this just a feeling with an undefined level?

If only you'd listen to my various files and email me your choices, we'll all have the answer. That's why I made those files, so we don't have to argue endlessly about what can or cannot be heard. But those who can't accept that measuring and nulling trumps listening will never do this because they're afraid of what they'll find. The difference between me and some subjectivists is I'm glad to change my opinion in the face of compelling new evidence. Others, not so much.

--Ethan

 

[Ethan Winer]

In Ethans test, the only difference is the level of the interference signal, nothing to do with the entire system, just the source. The better your system and ears are, the lower down the signal can be before you can no longer hear it.

Yes, and another value of my test is that people play the files through their own systems. If they came to my place to be tested, they could claim my system isn't "revealing" enough to hear the artifacts.

Ethans experiment is easier, because you can hear the interference signal loud to start with, then go down in level. A more difficult, but accurate test, is to bring the interference signal up from below audibility until you can hear it.

Yes, raising the level is a better test. My goal in the video was just to demonstrate level versus audibility, not to create a formal test that arrives at actual numbers. My demo requires people to be honest with themselves.

--Ethan

 

[treitz3]

TAS, by pulling a fast one, using a tube amp, think about it, TAS also allowed Carver to prove that the licquid midrange of tubes was nothing special and could be duplicated as well with a solid state amp.

Hello, Tom. Maybe with what has been written in articles but even to this day, Bob will admit that it will only get you part of the way there. Not all of the way. I am of the impression that the "golden ears" weren't really all they were cracked up to be for that challenge.

Tom

 

[jkeny]

...
Anyway, while waiting for your responses to my questions, in that test, the issue was that they used a transformer output amp, and it sereiously messes up low frequencies, so, to compensate, he tweaked some stuff by ear in his amplifier. And all agreed it was inaudible after that or did not matter.
[/B]

Do you understand what you are saying? They had a 70dB null but the amps sounded different. Therefore a 70dB null is no guarantee of two amplifiers sounding the same. QED

Guess you have to try again with a new value for this measurement, eh?

 

[microstrip]

I will accept the Carver challenge at face value, -70db NULL!

Thanks. I will try to measure the null between one channel of a Dartzeel amplifier completely cold and the other after some warm up. This amplifier sounds completely different after one hour, perhaps less, warmup, so I am curious about the result. Unhappily I am not able to it for the next few days - may be early next week. And yes, I have the famous ten turn attenuators - even Mark Levinson used them in his line of electronics in the early 80s.

 

[jkeny]

OK, Tom, if I confused the message in the article then I apologise but I read it differently - I read it that he had achieved 70dB null but still needed to tweak it to make it sound identical.

 

[DonH50]

I did not go back and read the article. My memory is that he did not achieve the desired goal in the initial (24 hour?) time period but did after another evening of fiddling, at which point nobody could tell between the two amps.

 

[jkeny]

I think where it gets confusing is that he achieves a 70dB null on page 3:
"The next day he had managed to boost that 50dB figure to 70dB, and felt ready to try some listening. By this time the difference signal between the amplifiers was audible only with an ear glued to the Rogers LS3/5A, even with the output of the amps cranked up. There was no doubt that Bob had achieved something impressive, but we questioned whether it would translate into true duplication when driving real-world (and difficult-load) loudspeakers. We moved the project to my listening room."

It seems that in the writer's listening room, the null achievable was only 35dB & there were noticeable differences between the amps! After some fiddling he claims that he has it but there are still audible differences. He tweaks the LF output but there are still differences in sound stage. "More interesting, though, and disturbing, was that the soundstaging had now changed, and the two amps were no longer the same. It turned out that Bob had to go back and diddle some more, exhausting his 48-hour limit."

Then he writes this:
"After this last bit of tweaking, where Bob was able to reinstate his 70dB null while driving a very difficult load, we now had what sounded like two absolutely identical amplifiers."

 

[Raffles]

Yes, I've read the story of this 'Carver Challenge' and it does sound a bit weird. He apparently stuck lots of pots all over the amp (an RF/noise/stability nightmare?) and tweaked until he got the 70dB null. To my mind, a more likely story is that the the audibility of differences between the amps was merely psychological all along (it wasn't a blind test), so the pots and null were decoys, and all he did was spin a good story and give the reviewers enough time to persuade themselves that they couldn't hear a difference.

 

[Phelonious Ponk]

OK, Tom, if I confused the message in the article then I apologise but I read it differently - I read it that he had achieved 70dB null but still needed to tweak it to make it sound identical.

Correct. He had to make the reference amp sound worse.

Yes, I've read the story of this 'Carver Challenge' and it does sound a bit weird. He apparently stuck lots of pots all over the amp (an RF/noise/stability nightmare?) and tweaked until he got the 70dB null.

Perhaps you've read some story of The Carver Challenge, but it's clear you haven't read the actual Carver Challenge story, because what you said above is nonsense. The really isn't that hard, guys. Just read the real thing.

http://www.stereophile.com/content/carver-challenge

Tim

 

[NorthStar]

---Tim, you are a writer; regarding, and for who? ...Just curious. :b