John Curl's Blowtorch preamplifier part II

[scott wurcer]

Originally Posted by RNMarsh

Long before Vol 4 of Linear Audio came out, i said here that there was plenty of reason to think very low distortion was audible. I did my own distortion threshold tests and found that we needed AT LEAST .01% was max distortion to design for. And because we listen to a whole system, we needed products with -100db or better in each so the total of the entire system was below threshold. Well, Vol 4 shows even lower thresholds are detectable. This puts a new light on things... about our equipment and about listening tests.

The total will always involve random vector addition and approach a root sum of squares not linear addition so to get from -100dB to -80dB you would need 100 components in series. No speaker even approaches these numbers anyway. We also know how to make amplifiers that are second and third harmonic dominated by a wide margin. I don't see THD factoring into the sound of anything unless it is the "sound".

BTW where in Vol. 4? I don't remember anything but anecdotal references.

[Esperado]

Originally Posted by scott wurcer

The total will always involve random vector addition

I never worried about phase in harmonic distortion's products, but can't we think they are correlated with the phase of the fundamental frequency of the original signal everywhere they are produced, at least for the first orders ? I mean, like clipping...
Amusing to see how our posts are in phase about this subject :-)

[SY]

Originally Posted by scott wurcer

BTW where in Vol. 4? I don't remember anything but anecdotal references.

You remember correctly. I scoured the article about listening/measurement correlation for actual listening data and was sorely disappointed.

[john curl]

I guess I should put a word in here. I can't argue anything on these topics, because the opinions here are based in limited information coupled with a lot of strong opinion.
Personally, I trust my ears to tell me what is important or not.
Secondly, I have studied, and continue to refer back to even early comments on THD, IM, and TIM to get a better understanding as to what 'should' be audible.
I generally ignore loudspeaker harmonic distortion, as it does not appear to 'blend' with the amp differences.
The Hirata test shows a significant difference between distortion generated in loudspeakers vs electronics, and just the opposite results are found than people here would nominally predict.

[Esperado]

Originally Posted by john curl

I guess I should put a word in here. I can't argue anything on these topics, because the opinions here are based in limited information coupled with a lot of strong opinion. Personally, I trust my ears to tell me what is important or not.

While your informations are not limited and your opinions so open minded ?
I'm so sorry, but i don't trust your ears because, happily, i'm not in your brain. I even not so much trust mine and i don't believe they are the center of the world.

Never in my life, never, i had met any talented person satisfied with himself or arrogant. And more they are famous, more they are modest and kind. Because self satisfaction and arrogance is just a wall between us and any learning or discovering.

In no way you can justify that H2 or H3 produced by a loudspeaker is different from H2 or H3 produced by anything else, apart their levels or phase.

I'm sure you can justify what you assert, but please, provide maths. Not brutal and vague assertions provided by... Who ?
And because i believe we (Scott or I) do not differ in what we said from what you can think (HD is not the main issue) i don't understand your smoggy intervention.

[Esperado]

About our listening certitudes, the frequency range of our ears decreases after 30 years. And women listen more trebles than men. As everybody knows.
If we lie too much on our ears, after 50, we will produce old stuff for old people.

[john curl]

Yes, I am very open minded. I will try just about ANYTHING. If it works, it works. If not, then I reject it, even if I cannot measure a problem.

[jcx]

Lukin sneers at UV22 dither as "old man's dither"

[john curl]

For those who wish to further understand my position, I asked the SAME QUESTION, 40 years ago to Richard Heyser (if you don't know who he is, Google his name).
I was not alone, 3 engineers in total, including me, went to see him, in order to get an answer as to why loudspeakers can have significant distortion, yet we can hear differences in amps and preamps, with much lower distortion.
EVERY TIME, I give Richard Heyser's answer here, I get hoots, etc. However, I took his input seriously, and that is one of the reasons I have had a very successful career in audio design. My associate, Bascom King, who was with me at that meeting, 40 years ago, now designs, as I do, for Constellation, making power amps. You might check out his efforts.

[john curl]

In my relatively old age, I am continually surprised what I can still hear, especially as differences in audio equipment.
Last week at this time, I was reporting my listening opinions to OPPO, as to their new 105 audio outputs. Of course, the engineers have a hard time believing me, because THEY trust their test equipment. I use both test equipment and ears, but I have MORE experience in highest quality audio design, and that makes the biggest difference.
On the same day, I listened to the latest version of a new amplifier design that we have worked on over several years. It sounded OK, but other limitations in the $100,000+ audio playback system spoiled the demo. Now I have to help my colleague get a Vendetta playback to make his vinyl sound as good as his digital, which was superb.
I still don't like digital much. It's good enough for movies and TV, but when I am listening to music, I need more. I think I was born this way.