John Curl's Blowtorch preamplifier

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#14,081
Joshua_G said:



By what criteria they "cut themselves down to size"?
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Not criticizing the issue but the person, opinions not based on the facts but on who utters them, personal attacks, and a couple of others. I do not expect you to understand this; in fact I do not expect a whole lot from someone who still thinks in 'lesser' and 'greater' persons. And yes, this is an attack on your personal opinions.

Best regards,

Jan Didden
 
#14,082
janneman said:



Not criticizing the issue but the person, opinions not based on the facts but on who utters them, personal attacks, and a couple of others. I do not expect you to understand this; in fact I do not expect a whole lot from someone who still thinks in 'lesser' and 'greater' persons. And yes, this is an attack on your personal opinions.

Best regards,

Jan Didden
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Your second sentence contradicts the first one.
 
#14,086
Edmond Stuart said:


Hi Frank,

Apart from the question whether speakers produce more even harmonics than odd, any symmetrical system produces odd harmonics.

Regards,
Edmond.
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He probably meant low order distortion. This is more evidence as to how bad phono reproduction is. There is significant 2nd order going on. Think of an ellipse tracking a sine wave it does the "out" peak fine but can't quite get the bottom i.e. asymmetry.

I still love my LP's.
 
#14,087
NOTHING is benign. However, we seem to be able to tolerate a fair amount of distortion from speakers or headsets that we usually would condemn in electronics. Why?
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Is it IMD multiplication? NP's paper said something about this. Loudspeaker, LP, magnetic tape, they all produce quite some distortion in "stand alone" mode, but from the source POV, they operate open loop, they all don't have feedback which can produce IMD multiplication (unlike global feedback amp). The magnitude of IMD multiplication product can be higher than the signal itself.
 
#14,088
Lumanauw, you are correct. Negative feedback is one of the major factors. It is a matter of what we are measuring. Many engineers wallow in FFT based harmonic and IM testing. How about FM modulation? etc. etc. The Hirata test is extremely revealing in this case.
 
#14,089
I might emphasize the 'Hirata' articles published around 1980 in the AES. This test is unique in that it can measure amp problems THROUGH loudspeakers and microphones. It seems to pick the subjectively good electronics from the bad. How it does it, I have never been able to explain to myself, even with the equations in front of me. Perhaps, someone here can explain it better, once they look through Dr (professor) Hirata's explanation in his papers.
 
#14,091
Please Scott, talk to Dick Sequerra about this. Insist on it, get beyond the polite banter that you two exchange. He will tell you better than I can tell you, IF you will try to accept what he has to say about FM distortion.
Klipsch overstated the problem in many of his examples. Ask John Meyer, if you don't believe me.
 
#14,093
john curl said:
I might emphasize the 'Hirata' articles published around 1980 in the AES. This test is unique in that it can measure amp problems THROUGH loudspeakers and microphones. It seems to pick the subjectively good electronics from the bad. How it does it, I have never been able to explain to myself, even with the equations in front of me. Perhaps, someone here can explain it better, once they look through Dr (professor) Hirata's explanation in his papers.
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For reference there was a discussion about the Hirata test back in post #2534.
 
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