John Curl's Blowtorch preamplifier part II

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jan.didden

jan.didden

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RNMarsh said:
No accounting for what people like. Lacking experience in correlating what is heard with measured distortion, possibly. Those individuals dont get to be in on the next round of listening.

I would like to know the FFT of the 100 Ohm condition as it will indicate just how sensitive the listening test was. But if I can hear it thru my port pc speakers ... it must be really high, right? Right?

THx-RNMarsh
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Well yes, I don't doubt that someone with a lot of experience like you or JC (as Nelson likes to say, at least 10,000 hours listening time) would become quite sensitive to even small differences. But 99% of Joe Listener isn't. Yet we are to believe that ANYBODY with ANY SYSTEM at ANY TIME and ANY PLACE can clearly here a difference that even the worlds best instrumentation cannot find.

I believe it is that critique-less, illogical and unthinking attitude that gives the 'subjective camp' if I may be so bold to use that term, it's bad rap.

Jan
 
Mooly

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SY said:
Mooly, I'd recommend a sorting test. PITA for you (you'll have to do 10 recordings), but very effective and tougher to game than foobar ABX.
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I remember the last time ;)

There is a lot of work involved even for the basic stuff, the test tones and so on. I'll think on it. Those that want to do it fair and square will, and those that want to throw software at it can, and then see if they can tie up the results.
 
Esperado

Esperado

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SY said:
You're male, old, ugly, and European. Lots of evidence. Thank you, but no.
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You are American, But i don't believe it is the reason why you are supposing and were not able to understand what was behind my firsts answer. I agree it was a little subtle.
The sens was: "There is no data to support our feelings (even the sense of beauty)".
 
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fas42

fas42

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gpapag said:
Frank, I am not criticizing anyone’s work and contribution here, I try to spot the limits of realistic testing with these files.

X,Y were uploaded as 48k sample rate files. This means that single sample accuracy alignment is bound to be 21 us (20.83us).

This limit is set at the recording end and we can’t time align the recorded events to a smaller time step at a later time.

By upsampling the files at the replay end, we can time align to finer time steps the recordings as a whole but not the recorded events themselves.
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George, there are two important elements in this: the passing of the signal through two varying chains of amplification; and the recording of the results. Either element can introduce distortion, for any reason, in the process. What we have in our hands to look at, or for our ears to hear are only the final step of the entire process - and it's clear that there are significant differences. Arguments and discussion can proceed as to what caused the differences, but first it needs to be accepted that "interesting" differences are there.
 
fas42

fas42

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Pano said:
The differences you are finding are mostly due to level mismatch and/or time alignment. It took me quite a bit of work to get the null I did.

You need to get the levels right and especially get the timing right for a null. And there seems to be a drift of about 2 samples over the length, not that a drift like that would affect the midrange.
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Sorry, Pano, incorrect. I have done quite a bit of this type of thing, and have gone crazy with upsampling to ridiculous, multiple Mhz sampling rates to precisely align different versions - these two are beautifully aligned, apart from the single step difference in the start, as is; from the beginning of the files to the end.

There is a variance, a drift, of level through the files - some resistance value was still stabilising perhaps, the gain of the chain for at least one sample was not constant.

As far as I'm concerned, the time domain behaviour is where the answers are - a single glitch, in the wrong place, will scream out "wrong!!!" to one's ears - but will be almost invisible in the frequency domain picture ...
 
mlloyd1

mlloyd1

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Richard:

Picking up on your comment - it probably would be useful to have some training on what certain distortions sounds like.
What's a reasonable way to get some?

You, Charles, Nelson and others have (sometimes indirectly) commented previously about a "magic" number of hours of listening - maybe it was 10,000?

Any suggestions on how could folks who have no intention of making a livelihood in this (i.e. hobbyists) get a decent crash course? Such a foundation might even improve some of the conversations around here.

OK, OK, one can always dream ...
;)

mlloyd1

edit: I see Jan touched on this, too.

RNMarsh said:
No accounting for what people like. Lacking experience in correlating what is heard with measured distortion, possibly ... THx-RNMarsh
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fas42

fas42

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john curl said:
One hundred ohm loading is extreme. I have, however seen 300 ohm loading, and even that is too much, I think. Many other IC's that are more popular here are not designed for 600 ohm loading to the extent that when you load them with 600 ohms, they get very unhappy. 100 ohms would be overwhelming for typical IC's. The 4562 is a notable exception, actually. For example if you want to see what the 2134 does, just look at the Stereophile review of the JC-3.
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If one looks at the spec sheet for an opamp it's obvious that they shouldn't be excessively loaded - the short circuit current, or equivalent, is a giveway as to what the limits are; a bit of maths then tells one what the lowest, half reasonable load would be.

You could buy a small car that states it's capable of 120mph, and then drive it all day at that speed - but you wouldn't be the brightest kid on the block doing that ...
 
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