I have a pair of them in my MM phono preamp, which coincidentally was designed by PMA. But I only ever bought the two of them, so I know you're not referring to me.
I have a pair of them in my MM phono preamp, which coincidentally was designed by PMA. But I only ever bought the two of them, so I know you're not referring to me.
I probably should have said continued existence, but I don't really know the current situation. East coast folks are a little conservative, putting an op-amp in a TO can for audio like what Nat Semi did (is that still around?) would never fly here.
That looks like a hearse (sp?). And you were so young!
Jan
Pontiac Grand Safari, IIRC ours was a '59. I failed (8 or 10yrs. later) parallel parking (for obvious reasons) but the tester went easy on me.
I've worked on projects where the cost of re-qualifying for a different part was not worth the BOM savings. I'm sure anyone whose been involved with a mission critical application (or potential lawsuit critical) has seen the same.
I checked back on Wayne's comments on the MUSE opamps and he said the changes were 'from the lead frame up', which suggests std silicon with fancy lead frame. Certainly can't think the volumes justify a mask rev.
I checked back on Wayne's comments on the MUSE opamps and he said the changes were 'from the lead frame up', which suggests std silicon with fancy lead frame. Certainly can't think the volumes justify a mask rev.
I think it doesn´t depend so much on the question if it is scientific or not but on the question if a test (and its results) justifies the conclusions drawn or not.
Even if the attempt will not fullfill every scientific requirement it it nevertheless supposed to give insight.
I was suprised because PMA asserted earlier in this thread that the results would not allow statistical analysis because of the small number of participants and the obvious inconsistency.
The later posted messages didn´t reflect imo this assertion.
While it is a valid (and plausible) hypothesis that different opamps are under certain conditions (means "shielded/guarded" against any/most EMI effects) indistinguishable it needs valid test results for confirmation/corroboration and it has to be confirmed too that still the best possible sound quality is achieveable.
@PMA,
maybe i misunderstood something but to insist on ABX results doesn´t really help. The ABX protocol might be useful in some cases but for good reasons it is not widely used in the audio field and their is no real reason to force people using it.
Then why not gold plated cerdip? OFC copper lead frame is in the marketing jabber, along with some questionably translated audiophile buzz. I notice it's still tin plated to pass solderability, how silly all this is.
Jakob2: In audio ABX protocol was used for development of loosy audio codecs [1].
IMHO it can be also used for examining "sound of opamp" if a such effect really exists.
So far nobody has demonstrated positive ABX result of original file (ww) vs. any other file from this test.
So we can assume following:
1) PMA has good enough DA/AD chain that does not influence the sound of used audio recording in this test
2) none of tested opamps does change the sound of used audio recording (for human hearing)
If you do not agree, you can try to provide either positive ABX result, or invent your own testing protocol that would demonstrate that my assumption above is not true.
Nevertheless a difference of sound in this test seems to be much much smaller than between any loosy codec compression and original recording!
[1] https://en.wikipedia.org/wiki/Codec_listening_test
IMHO it can be also used for examining "sound of opamp" if a such effect really exists.
So far nobody has demonstrated positive ABX result of original file (ww) vs. any other file from this test.
So we can assume following:
1) PMA has good enough DA/AD chain that does not influence the sound of used audio recording in this test
2) none of tested opamps does change the sound of used audio recording (for human hearing)
If you do not agree, you can try to provide either positive ABX result, or invent your own testing protocol that would demonstrate that my assumption above is not true.
Nevertheless a difference of sound in this test seems to be much much smaller than between any loosy codec compression and original recording!
[1] https://en.wikipedia.org/wiki/Codec_listening_test
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A remix of Pavel's test files.
I think the ABX criticisms are quite possibly valid. I certainly find with my own stuff that it is only on longer 'relaxed' listening that consistent differences seem to make themselves felt.
I took the CA1458 (tt) and the original ww file and chopped them somewhere in the middle ground and then joined them.
Worth a listen ? Its not a spot the join test, its simply does one half have more musical appeal than the other and if so which. And they could be any way around remember
Just one track:
https://www.dropbox.com/s/yrutps7yjnftbte/Mix.zip?dl=0
I think the ABX criticisms are quite possibly valid. I certainly find with my own stuff that it is only on longer 'relaxed' listening that consistent differences seem to make themselves felt.
I took the CA1458 (tt) and the original ww file and chopped them somewhere in the middle ground and then joined them.
Worth a listen ? Its not a spot the join test, its simply does one half have more musical appeal than the other and if so which. And they could be any way around remember
Just one track:
https://www.dropbox.com/s/yrutps7yjnftbte/Mix.zip?dl=0
ABX got some interest as tools were freely available quite early on windows computers, but the main development in the lossy compression codecs were done with ABC/HR, it fact that method was invented to do the evaluations experiments.
Of course it can be used, as every other test protocol can be used either.
But, as said quite often before, the original ABX was introduced in the mid 1950s - have to look for the exact year - and other experimenters did some comparisons to paired comparison test results. They attributed the differences in the results to the obviously different internal mental processes.
Undoubtely some people reported quite impressive listening results using the ABX protocol, see for example Paul Frindle´s list in his AES convention papers, so its a valid hypothesis that some people can get good results under the ABX conditions, but training and accomodations seem to be mandatory. Using positive controls will ensure sufficient sensitivity.
To use the usual term, the results so far only mean that the null hypothesis could not be rejected.
Imo we don´t know about the quality of the DA/AD chain as no unprocessed reference was supplied.
Wrt to your second conclusion, i think i´ve supplied my argument why that is a bit suspicious.
I beg your pardon, but i think pointing out the somewhat questionable arguments is already permitted
(Not meant to be offensive)
No free parameters magnitude vs time, do you propose some hidden variables that would rewrite information theory, thermodynamics, etc?
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