Although really good speakers help in the evaluation process (good roomacoustics as well) the speaker we used at that time wasn't anything special, just a small two-way speaker with a transmissionline woofer and a 25 mm tweeter from Vifa.
That is one of the reasons why other people often doubt these allegedly audible difference, because they instantly assume that the much larger differences caused by the speakers must mask the smaller differences between capacitors.
I'll give these newer SMD types Bonsai recommended a try (he is right, sometimes there must be a capacitor) but otherwise no capacitor seems to be the better choice (servos do have some problems of their own, though).
Op-amp rolling is a waste of time, IMO dropping in a new amplifier requires a total look at the associated circuit possibly a re-engineering and qualification, otherwise it is just more random data.
With all the talk I see little science going on.
Agreed. Problem is once you are into the territory where you need an AP or Dscope suddenly we get into the twilight zone for many.
I'm not fussy. If its beyond the ability of a souncard or Scarlet to measure it's not something I can lose sleep over.
Deterministic jitter should be much easier to identify since it would be specific tones following the signal as opposed to noise, kind of like IM. Thresholds of audibility of this would be something to address. Most of the bad stuff on newer DAC chips are at the level where its questionable that a transducer would be able to overcome intrinsic inertia or stiction let alone be audible. Still its conceivable that with a complex mix of tones the "bad" stuff could show up.
However random jitter will just be noise skirts on signals which should be far more benign.
Experiments with different clocks, cables etc. can be very hard to properly conduct since its so difficult to confirm that what you think you are testing is the only aspect. Coupled noise and harmonics on a clock via radiation may well show up differently and who knows what other things are in play. The differences may be audible but accurate attribution would be hard work.
Generalisation, again, OMHO.
I did a lot of "Op-amp rolling". Of course, it implies a modification of the comp cap, most of the time, and to choose the right Op-amps for the purpose.
The difference on the overall quality and sound character can be obvious.
While we have to avoid any generalisation on the results, like "this one sound better", because it depends on the associated circuit (comp, decoupling, impedances), it seems to me that to profess :"is a waste of time" is a hasty generalization of the same kind.
Would this popularization writer sit on the right hand of God?
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Admitted that it is a simplified categorisation compared to the reality, but it is IMO a fair description of one side in the so-called "Great Debate" .
I agree and we have shown exactly that in our various test attempts, but there is a group constantly denying it.
As Stanley P.Lipshitz wrote in a letter to Stereophile:
"In my experiences over a dozen years, audible differences frequently occur—differences which survive even when subjected to a rigorous blind test. These differences, however, have invariably turned out to be due either to a level difference (half a decibel will do it), a frequency-response difference, a difference in polarity, a nonlinear distortion, or an overload phenomenon of some kind in one or another of the components being compared. What I have found, and what I do maintain, is that when these well-known and easily measured performance differences are reduced to sufficiently small amounts so as to be inaudible (a situation which obtains, for example, in most high-quality amplifiers nowadays), the two components no longer sound different."
(Deeper Meanings Letters part 5 | Stereophile.com)
The same was stated wrt so-called Clark amplifier challenge; most differences were attributed to linear distortions that must be equalized by an EQ and after that no-one was able to hear a difference between power amplifiers.
(Of course excessive other kinds of distortions were ruled out before)
It was reported that - despite that a couple of thousand listeners tried this challenge - no one ever had more than 65% correct responses in the ABX tests; due to statistical reasons I've my doubts as it is an extremely unlikely outcome.
Most of this mentioned group take it as a given, due to all the measured numbers when comparing CD-players to vinyl record players.
But the same group seems to be unwilling to accept that CD players could sound different if the measured numbers are below the threshold (means all are below the....)
I can remember the outrage of a lot of EE when the first german audio magazines in the mid 80s wrote about audible differences between CD players. Letters were flooding the mag.
I totally agree and think it is a honest approach.
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@Tournesol,
most likely a matter of definition; I'd assume that Scott Wurcer uses the term "opamp rolling" for the case where opamps were exchanged _without_ checking the conditions/variables (like compensation, impedances, loads, decoupling etc.)
most likely a matter of definition; I'd assume that Scott Wurcer uses the term "opamp rolling" for the case where opamps were exchanged _without_ checking the conditions/variables (like compensation, impedances, loads, decoupling etc.)
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Did you really read and compiled what 1audio is saying, or you used his message to score a cheap shot?
If you claim you can discriminate, ears only, non pathological amounts of deterministic and non-deterministic clock jitter then, until you can show evidence, you are full of it.
Showing the jitter threshold values (the Dj(δδ) in a dual Dirac delta deterministic jitter model, and the average and dispersion for the Gaussian non-deterministic jitter) from which you can successfully discriminate, ears only, their effects would be acceptable evidence.
You left out "show me the evidence". 🙄
Oh, that's right, it's the debate tactic that you use (despite your criticism of it) here.
The reason why i reacted this way is Scott is surrounded by an aura of authority and claims to have an objective attitude. To read his comment, you would think that he says that all Op-amps "sound the same". Which is false, from my personal experience both on listening and measurements.
Of course "op-amp rolling" implies and requires it is done with a correct engineering.
When a car tester publishes a report, this implies that he have a driving license, has filled the tank with the correct fuel, and about generalization, that his opinion on comfort on the road was not acquired after a test on dirt roads full of stones ;-)
He's a good man! If the AP says the distortion is zero, its zero.
Proceed forward confidently!
Already have, built the one published in Linear Audio 🙂 The op amps are in sockets for easy rolling 😉
Chassis are fastened with standard screws for easy opening and painting with goop. 😉
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