John Curl's Blowtorch preamplifier

[stinius]

More like 'ignore evidence outside of the predetermined goal' kind of guy.

Isn’t that more or less the same thing?

BTW: talking about amps
Are you guy’s looking for a linear transfer function of the amp or a very low THD?

 

[john curl]

Transfer function is most important in typical audio designs.

 

[stinius]

Transfer function is most important in typical audio designs.

I agree, but it seems like a lot of people are only chasing the low THD (that involves a lot of GNFB).

 

[Edmond Stuart]

I always thought that low THD implies a linear X-fer function and vice versa. Am I wrong?

 

[john curl]

You can get the same THD, but with less negative feedback.

 

[jan.didden]

Nelson, who was this guy from SUNY who dissed you,(and others)?

Would that have been GG from Potsdam SUNY?

Jan Didden

 

[Jakob2]

Sorry missed that, though it is strange they don't give much attention to the subjective tests. And yes, there are contradictory findings between here and elsewhere.

I find the loudspeaker issues in both studies are difficult to deal with. It would be hard to find a speaker that eliminates the intermodulation issues that would be a normal commercial component for home use.

The somewhat more objective measurement through PET and EEG was the exciting new part of this paper.

Quite a bigger effort than usual, so that may be the explanation why they didn´t write more about the subjective evaluation of the experiment, especially as there was correlation between PET/EEG scans and the subjective evaluation.

The design of the speaker used was done by Oohasihi, one of the authors, intermodulation can be avoided, but the interference between super tweeter and tweeter is a severe problem. The study covered this, but it´s still not obvious to me which filter configuration was used in the psychological evaluation; was it the 26kHz version whith 170db slope to avoid interference below 20 kHz or the other, which probably suffered from interference?

 

[Nelson Pass]

Nelson, who was this guy from SUNY who dissed you,(and others)?

Honestly, I forget, but it was a letter to Ed Dell also.

 

[john curl]

Do you have approximately, what year that was, Nelson?

 

[vuki]

The somewhat more objective measurement through PET and EEG was the exciting new part of this paper.

Yes, even if there was intermodulation, interesting is that it was prefered (according to alpha waves) to ultrasonic-free reproduction.

 

[Nelson Pass]

Do you have approximately, what year that was, Nelson?

1982. The criticism was on my article of phase correct crossovers.

 

[Jakob2]

Yes, even if there was intermodulation, interesting is that it was prefered (according to alpha waves) to ultrasonic-free reproduction.

Intermodulation was avoided during the experiment as the high frequency component was send exclusively to the supertweeter.

 

[PMA]

Do not forget natural distortion in human's ear, sharp cutoff eliminates natural intermodulation ear products.

 

[1audio]

Without having seen the article I would ask if the supertweeter was in a meaningful phase relationship to the main signal. If it was significantly separated it may become disconnected from the primary event in the hearing process.

I am aware of some unpublished work indicating very fast response, on the order of 10 uS, to acoustic stimulous. This is in the acoustic nerve before processing. Not having references I don't want to make any further implications about the work I'm mentioning, but if true it would suggest that ultrasonic information may be processed before the normal processing we call hearing happens.

 

[PMA]

Yes, firstly time domain info counts, then 'spectral analyzer'

 

[jan.didden]

1982. The criticism was on my article of phase correct crossovers.

The only SUNY professor I know that regularly writes Ed is Gary Galo.

Jan Didden

 

[scott wurcer]

The only SUNY professor I know that regularly writes Ed is Gary Galo.

Jan Didden

No, it was definately not him. Unfortunately I threw out my copy, it basicly said we could not possibly get anything but a perfect null in our tests no matter what capacitors we used.

 

[Nelson Pass]

The only SUNY professor I know that regularly writes Ed is Gary Galo.

No, not him. As I recall, his argument was technically correct, but it
missed the point that I was trying to simplify something for amateur
consumption, not academia.

 

[john curl]

Nelson, went through 82 and 81, nothing yet. Will now try 83.

 

[Nelson Pass]

John, I don't recall that it was published in the magazine.

Why such interest?