John Curl's Blowtorch preamplifier part II

[Wavebourn]

Originally Posted by scott wurcer

I would like to see the math for the non-harmonically related frequencies or how three orders of magnitude more PM in a speaker than an average amplifier does not matter.

Unfortunately Scott you can't see the math of perception. But according to many researches (I'm not name-dropping) we perceive and compare by similarity. If distortions mimic what we expect to hear in the nature we ignore (filter out) them; we do that all the time recognizing sounds passed through the air, through walls, reflected by different non-linear surfaces and so on, and the more they differ the more of processing is needed to reconstruct and recognize sounds. It leads to a listening fatigue that can't be measured precisely, but can be used as an indicator.

Vintage speaker are more venerable, they cost more than modern ones. Why? Because on the run for lower THD numbers designers made speakers that produce more alien to the nature distortions, but anyway they are mostly mechanical devices, so their higher THD and PM levels add less of unnatural errors than amps do.

[janneman]

Originally Posted by john curl

They convinced me, already. But then I am more willing to learn new things, and accept that some people actually know more than me about it. I do have a call into Mitch Cotter. He is tied up on his project, but I did leave a message asking for further details, just 1/2 hour ago. It may be until tomorrow, before I hear from him. I have tried over the last 18 hours, already.
Personally, I don't need to convince anyone here about anything. It is your gain or loss to follow up. It is now obvious to me, but it is because I participated in presenting the original graph, and did dozens of separate measurements, myself, in Matti's lab, getting the same graphs. I KNOW the test procedure, and its correctness.
What Mitch Cotter contributed, was NOTING the FM distortion as it would appear on the same graph. He showed Matti, Matti verified it, himself, (didn't tell me), thanked Mitch, then wrote his first paper on PIM, ALL math, no measurements. I just met up with Mitch a few months ago, and we talk almost every day. Does this help?

Not really. I'm stil being asked to believe your and Mitch's blue eyes. If you understand it so well, and are so strongly convinced that it is correct, why not explain what's going on?

jd

[Juergen Knoop]

Dear Anatoly,
you tend to babble.
Please explain precisely, are you spicing up the soup (=add distortions and other artefacts for better sound) or not?
Regards

[janneman]

Originally Posted by Wavebourn

Unfortunately Scott you can't see the math of perception. But according to many researches (I'm not name-dropping) we perceive and compare by similarity. If distortions mimic what we expect to hear in the nature we ignore (filter out) them; we do that all the time recognizing sounds passed through the air, through walls, reflected by different non-linear surfaces and so on, and the more they differ the more of processing is needed to reconstruct and recognize sounds. It leads to a listening fatigue that can't be measured precisely, but can be used as an indicator.

Vintage speaker are more venerable, they cost more than modern ones. Why? Because on the run for lower THD numbers designers made speakers that produce more alien to the nature distortions, but anyway they are mostly mechanical devices, so their higher THD and PM levels add less of unnatural errors than amps do.

Scott didn't ask for any math on perception. He said: "I would like to see the math for the non-harmonically related frequencies or ...". He asked for the math explaining how non-harmonically related freq lines can show up in the spectrum. Or so I understood.

jd

[Wavebourn]

Originally Posted by Juergen Knoop

Dear Anatoly,
you tend to babble.
Please explain precisely, are you spicing up the soup (=add distortions and other artefacts for better sound) or not?

No, I don't. I choose methods that add less of nastiest errors.

[Juergen Knoop]

thank you!
regards

[scott wurcer]

Originally Posted by Bob Cordell

John,

You asserted that Barrie Gilbert's paper proved your point on PIM. That is not so, even though Barrie did not make any mistakes. I frankly think that you are very much in the habit of putting your own spin on what others say.

Cheers,
Bob

I just re-read, in part, Barrie's paper. The distortions are all related to the input frequency(s), the math BTW is not very complex. He shows a Taylor expansion of the first and third order on an input stage generates thirds, nothing remarkable.

[john curl]

Stage 2, Scott?

[janneman]

Originally Posted by scott wurcer

I just re-read, in part, Barrie's paper. The distortions are all related to the input frequency(s), the math BTW is not very complex. He shows a Taylor expansion of the first and third order on an input stage generates thirds, nothing remarkable.

So, that means John is plain wrong. Can we now move on please?

jd

[Juergen Knoop]

Originally Posted by Wavebourn

No, I don't. I choose methods that add less of nastiest errors.

so the absence of measurable inband products is good enough?
Regards