Christophe,
They can hear tiny differences. Now the point is, to pick preferences when no option is known to be a perfect option.
Ability to differentiate tiny difference is one thing, but I think sensitivity to "distortion" is another.
Many tube amps user can live with the system that will make my ears bleed. They can accept it, because their "priority" is different, or may be their "ability" to perceive "distortion" is low (so they are not so affected by it).
So there is this "fatiguing" character in a sound (you can call it a PIM or IMD products or anything, you are the expert). And may be people have different sensitivity so different priority also.
Class-D amps are very good in sonic. Imo, sonic is the most important parameter of enjoyable sound. So, it is not surprising if people like class-D. But class-D also has that "fatiguing" unmusical character. The question is now, do we have a high sensitivity to fatigue such that the extra ordinary sonic character is not important anymore?
I always/usually "doubt" those who think that those class-D amps are "the best".
When you frequent them all, knowns and unknowns, you know the stars are not often the bests.
More often a good combination of average talent, professionalism and clever attitude in order to get success.
Genius are often locked in their art, don't fish for sympathy, and what they achieve often too subtitle for the difference can be perceived by most people.
Success is more often due to coincidences, like winning to the lottery, than anything else, don't you think ?
Do you think Steve Job or Bill gates were good computer engineers ?
May-i give-you an example about my friend guitarist ? Each time i had the occasion to help-him, he was in the studio for some guitar solo on some singer's album. Not often in the final mix. You know why ? Because, when the singer was back on the track after this solo, he was looking sooo poor !
Did-you ever heard a *great* solo in a Madonna album ?
Yes, if we join blind test often enough (among audiophiles, not common people), we will be amazed how consistent they are. Many here really have no idea because they have never joined this kind of stupid activity
But I always find it funny when they sit down quietly like doing a meditation. I do it differently. Often I pay my attention to something else other than the music. But surprisingly we often come up with the same winner (tho I though my preference is different).
There is a very simple method to get an idea about how far we are from perfection in closed loop amplifiers. It is to look the bandwidth inside the loop, at the entrance of the second stage. it is flat up to...around 1Khz on the fastest amps (> 1Mhz)!!!!
Then the level increase by 6db/oct.
Those two curves are for the same amp, first in voltage feed-back configuration second in current feed-back. Notice the difference on the corner frequency.
Then the level increase by 6db/oct.
Those two curves are for the same amp, first in voltage feed-back configuration second in current feed-back. Notice the difference on the corner frequency.
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There's no trap Jay. Either we'll find people who can tell the difference between Blowtorch and an evil 4558 or we won't. I shall be very disappointed if we don't.I think it is a good idea to choose 4558 than the other better opamps, so some engineers who do not believe in cable differences will be able to hear the differences also, then the trap is to make them choose the 4558
If the opamp have been AD8xx they will tell you that indeed AD8xx is better than Blowtorch. But when it is 4558, that is NEWS.
Then either people will prefer A: 4558 or they'll prefer B: Blowtorch or they'll prefer the yet to be determined C. Its as simple as that.
My point was, do amps with average slew rate cannot have flat phase response? This is to identify if the key word is "phase" or "slew rate".
It is not a question of reproduced "phase".
You can filter the input by a 6dB/oct low pass filter (recommended) and have a reduced bandwidth and reduced flat phase response, with only benefit on the perceived result.
The keyword is the slewrate inside the loop. IE the ability of the amp to respond to fast changes of signals.
All those *evil* components inside makes various errors. How fast will be this error corrected by the feedback ?
When i'm about to chose an OPA, i look in this order to:
Slewrate.
Output current (if i do not drive an other with very high input impedance).
Noise.
Distortion (sometimes
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Of course. I'm not accusing you are trying to trap JC
Often we hear people accusing adiophools being in hallucination when they say they can hear differences. They believe that if the BT is properly controlled, they will not be able to hear differences between A and B. And they challenge these audiophools to a controlled blind test.
So my idea is to challenge these scientists to a blind test. May be they will learn something new. For example, if they think A is better than B because A has lower THD, then lets see if they can recognize which one is A.
We can make a blind test where I bring $10 and $1000 amps and you bring $10 and $1000 amps. We can then take home the amps based on blind test
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All this explain the two opposite tracks we can follow.
The John's one, using few components, paired, matched, sorted, in a no feedback configuration, for generating few distortions in themselves.
It is a long, difficult and expensive process, not industrial.
Or to use the quick'n dirty way, with similar results. Using average components in VERY fast closed loop feedback configurations.
Once the design is achieved, it is easily industrial and less expensive.
With the progress on the components speeds, the second way takes more and more advantages. Note than, talking about components distortions, in the John's position, they matters. In the second way, they are corrected by the feedback process.
In fact, i don't disagree with him, i just follow an other method to hit the same target
The John's one, using few components, paired, matched, sorted, in a no feedback configuration, for generating few distortions in themselves.
It is a long, difficult and expensive process, not industrial.
Or to use the quick'n dirty way, with similar results. Using average components in VERY fast closed loop feedback configurations.
Once the design is achieved, it is easily industrial and less expensive.
With the progress on the components speeds, the second way takes more and more advantages. Note than, talking about components distortions, in the John's position, they matters. In the second way, they are corrected by the feedback process.
In fact, i don't disagree with him, i just follow an other method to hit the same target
I note with amusement that the last time a blind test was arranged in this thread (it was testing phase response), not only did John refuse to try, he spent much effort trying to convince everyone else to not try as well. Despite his best efforts, several people DID try the test. At least one of the "scientists" got a perfect score, despite the proclamations of the ignorant that "scientists" say "everything sounds the same."
So really, Ricardo, why are you whipping on that dead horse? You're not getting the use of the Blowtorch, you know that.
So really, Ricardo, why are you whipping on that dead horse? You're not getting the use of the Blowtorch, you know that.
No. But the fact that the noise is there to the extent it is,
but yet unspecified, is pretty powerfull on its own.
I think you may be missing the point. The DBT challenge to 'audiophools' (your word) is simply to check if they can actually do what they claim to be able to do: distinguish items on (unsighted) sound alone.Jay said:
The relevant test for 'scientists' would be: can you distinguish items by (unsighted) measurements alone?
It might then be amusing to swap over, as all scientists have ears and generally know how to use them but not all 'audiophools' have test equipment or know how to use it and properly interpret the results.
I would like to add a last philosophical word.
About numbers.
In the previous demonstrations, we have seen that numbers like slewrate have no absolute signification outside of their context.
Same thing about distortions, that everybody knows, todays, that they poorly reflect listening experiences. We have to know, in order to interpret those numbers, where and how.
Looking at numbers is a valuable approach for people which know how to figure-out their incidences in the ALL context.
There is NO contradiction between the scientific approach and the subjective (or artistic) one.
Both are about listening experience.
The scientific, on my point of view, require more previous knowledge, more learning time, but less time after, keeping you away to grope for a lot of things, taking apples for oranges.
About numbers.
In the previous demonstrations, we have seen that numbers like slewrate have no absolute signification outside of their context.
Same thing about distortions, that everybody knows, todays, that they poorly reflect listening experiences. We have to know, in order to interpret those numbers, where and how.
Looking at numbers is a valuable approach for people which know how to figure-out their incidences in the ALL context.
There is NO contradiction between the scientific approach and the subjective (or artistic) one.
Both are about listening experience.
The scientific, on my point of view, require more previous knowledge, more learning time, but less time after, keeping you away to grope for a lot of things, taking apples for oranges.
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No. We ALL know that $1 amp sounds different than $1000 amp. But when it is between $900 and $1000, some people start to ACCUSE others. The mission is to attack the person not the truth whether $900 and $1000 are different or not.
This accusation is simply based on the fact that these audiophools are really fools, don't know what they are doing, have no ability to measure distortions, etc. Not whether there is really differences.
Why is 1000V/us better than 60V/us? Is it audible (Talking about 50W or less)?
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Its not necessarily about the slew rate per se, rather higher slew rate correlates with better subjective impressions often (not always).
Take two opamps, with the slew rates you mentioned. The 1kV/uS is probably a CFB internally whereas the 60V/uS uses an LTP which is more RFI susceptible. Hence the former will probably sound better due to higher RFI resistance, but its SQ is nothing much to do with the slew rate number.
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