John Curl's Blowtorch preamplifier part II - Page 41

Wavebourn · 22nd July 2009, 04:47 PM

Phase shift itself when reactivity is driven does not create distortions; what does, non-linear output impedance of the thingy that drives.
Speaking of measurements, what may be observed, a phase angle between input and output signals. For better visibility the load may be plain resistive. And again, let me repeat myself: single-ended phase inter-modulation may be inaudible, when it mimics Doppler effect. Otherwise it sounds nasty. Long time ago I thought that it may be used for guitar effects. Nope! It sounds nasty when is non-linear and significant; I tried it with bass guitar thinking of aggressive sound. Gave up.

PMA · 22nd July 2009, 04:51 PM

IMO you will measure nothing important by this method in a standard good circuit.

scott wurcer · 22nd July 2009, 05:21 PM

Quote:

Originally posted by KSTR
So, is OLG corner > 20kHz (the no-quadrature condition in the audio band, isn't it?) less prone to HF demod? If so (I don't know), why?

- Klaus

Problem is the AD846 obsolete and missed by some audio guys was a classic CF video op-amp fully cascoded and DC precisioned so that the OLG corner was 400Hz.

PMA · 22nd July 2009, 05:38 PM

I liked the AD844 very much.

john curl · 22nd July 2009, 05:49 PM

Tom, get the open loop bandiwith to 20KHz and THEN we can talk.

scott wurcer · 22nd July 2009, 05:54 PM

Pretty easy on the AD844 the pin is there to cripple the VAS for any OLBW you want. I talked with Mitch for almost an hour and he's not telling much. I still think this stuff is a red herring but I'm not going to argue about it anymore.

PMA · 22nd July 2009, 05:56 PM

Pin 5.

aparatusonitus · 22nd July 2009, 06:07 PM

Quote:

Originally posted by john curl
Tom, get the open loop bandiwith to 20KHz and THEN we can talk.

What about AD825 then...almost 20kHz OLG?

PMA · 22nd July 2009, 06:12 PM

Yes, almost. But the AD844, e.g., is more than 10x faster, regarding SR, and it counts. OLG is quite same, but the AD844 is CFA, and it must be considered.

janneman · 22nd July 2009, 07:14 PM

Quote:

Originally posted by PMA
Yes, almost. But the AD844, e.g., is more than 10x faster, regarding SR, and it counts. OLG is quite same, but the AD844 is CFA, and it must be considered.

Also, the AD844 can be used open loop with excellent audio performance, howzzat for audio nirvana

You can set the gain by the ratio of two resistors (to pin 2 and pin 5).

jd

22nd July 2009, 04:47 PM	#401
Wavebourn diyAudio Member Join Date: Sep 2006 Location: Pleasant Hill, CA	Phase shift itself when reactivity is driven does not create distortions; what does, non-linear output impedance of the thingy that drives. Speaking of measurements, what may be observed, a phase angle between input and output signals. For better visibility the load may be plain resistive. And again, let me repeat myself: single-ended phase inter-modulation may be inaudible, when it mimics Doppler effect. Otherwise it sounds nasty. Long time ago I thought that it may be used for guitar effects. Nope! It sounds nasty when is non-linear and significant; I tried it with bass guitar thinking of aggressive sound. Gave up. __________________ The devil is not so terrible as his mathematical model! Wavebourn: We Create Creativity!

22nd July 2009, 04:51 PM	#402
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	IMO you will measure nothing important by this method in a standard good circuit. __________________ Pavel Macura, consultant http://cz.linkedin.com/pub/pavel-macura/4/783/637

22nd July 2009, 05:38 PM	#404
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	I liked the AD844 very much. __________________ Pavel Macura, consultant http://cz.linkedin.com/pub/pavel-macura/4/783/637

22nd July 2009, 05:54 PM	#406
scott wurcer diyAudio Member Join Date: Jan 2004 Location: cambridge ma	Pretty easy on the AD844 the pin is there to cripple the VAS for any OLBW you want. I talked with Mitch for almost an hour and he's not telling much. I still think this stuff is a red herring but I'm not going to argue about it anymore. __________________ 2012, our time is running out.

22nd July 2009, 05:56 PM	#407
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Pin 5. __________________ Pavel Macura, consultant http://cz.linkedin.com/pub/pavel-macura/4/783/637


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22nd July 2009, 05:49 PM	#405
john curl diyAudio Member Join Date: Jul 2003 Location: berkeley ca	Tom, get the open loop bandiwith to 20KHz and THEN we can talk.

22nd July 2009, 06:12 PM	#409
PMA diyAudio Member Join Date: Apr 2002 Location: Prague, Kitakyushu, Fukuoka	Yes, almost. But the AD844, e.g., is more than 10x faster, regarding SR, and it counts. OLG is quite same, but the AD844 is CFA, and it must be considered. __________________ Pavel Macura, consultant http://cz.linkedin.com/pub/pavel-macura/4/783/637

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