John Curl's Blowtorch preamplifier part II - Page 3500 - diyAudio
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Old 13th February 2013, 04:45 PM   #34991
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Quote:
Originally Posted by john curl View Post
Are you telling us that 'subjectively', you find higher slew rate better?
Why can't I say then, that 'subjectively' I find that open loop operation better?
Is your 'subjectively' better than mine? If so, how?
I had previously said that feedback and open-loop topologies are TWO different ways to reach the same goals, and even defended your choices.
And i just pointed than WITH FEEDBACK, i prefer high slew-rate and that is not a concern with open loop...What the hell ?
Why do you read everything in such a paranoid way ?
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Last edited by Esperado; 13th February 2013 at 04:48 PM.
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Old 13th February 2013, 04:48 PM   #34992
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Marce, I do audio design for an audio public. We use both discrete and SMD in our designs. I have little against SMD, except that it tends to exclude QUALITY CAPS and sometimes, resistors. We discuss the problems, all the time.
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Old 13th February 2013, 04:50 PM   #34993
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Esperado, IF you actually looked into what you are selecting, you would find that you are PROBABLY going for the higher quiescent version of the same op amp. Slew is just secondary to open loop linearity that you get with higher quiescent current. Please study up, and don't throw some cheap 60's mid fi amp at me, as an excellent example of design.
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Old 13th February 2013, 04:50 PM   #34994
PMA is offline PMA  Europe
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It is close to useless to waste time here, in this thread.
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Old 13th February 2013, 04:55 PM   #34995
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I love the bottom terminated devices, makes handling the heat on a populated PCB much easier, and as Scott has pointed out, you would be suprised what power densities you can achieve, even the new FET packages are more efficient that the old TO style PTH devices, mount them directly onto a ceramic heat sink with the copper pattern printed on the heat sink so you solder the device to said heatsink, and you get some realy realy low thermal resistance, so the device works optimaly, and with further implementation you can embed heat pipes into the heatsink and achieve some very high power, high slew rate RF designs in quite compact spaces...
I also do audio though mainly either professional gear, or communication systems, the parts are out there...

Last edited by marce; 13th February 2013 at 04:57 PM.
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Old 13th February 2013, 04:55 PM   #34996
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Quote:
Originally Posted by john curl View Post
Please study up, and don't throw some cheap 60's mid fi amp at me, as an excellent example of design.
Please provide your 'excellent example of design amp' done in 70. We will simulate and compare.
Your MID-FI pretentious argue is boring.
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Old 13th February 2013, 04:56 PM   #34997
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No, PMA, think about people other than yourself: They NEED TO KNOW. Vague criticisms need to be explained away. In any case, for Esperado's sake I will AGAIN post my main audio paper that I did in the 1970's without any other author:
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File Type: pdf omittedfactors.pdf (81.4 KB, 82 views)
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Old 13th February 2013, 05:04 PM   #34998
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Sorry, Esperado, my early schematics were burned up in the 91 firestorm. However, at the time, 1969, I designed a 2000W amp that was a complementary differential 4 quadrant bridge amp with 50V/50A output for Ampex Research. This was then converted to a floating balanced current source for motor drive operation.
The circuit you showed was typical of what was in 'Wireless World' at that time. My goodness, you have no idea what we were working on in those days.
BOOTSTRAPED driver stage! Quasi-complementary output. How quaint! '-)

Last edited by john curl; 13th February 2013 at 05:10 PM.
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Old 13th February 2013, 05:10 PM   #34999
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And what ? So, you agree with what i said, and we yet knew that at this time. I do not understand your position. Arguing with somebody who think the same way than you because some shadow on your glory and fame ?
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Last edited by Esperado; 13th February 2013 at 05:17 PM.
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Old 13th February 2013, 05:12 PM   #35000
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Quote:
Originally Posted by john curl View Post
However, at the time, 1969, I designed a 2000W amp that was a complementary differential 4 quadrant bridge amp with 50V/50A output for Ampex Research.
Slew-rate ?
i'm not impressed by power, i had some very poor sounding Crown power amps, and i thought we were talking about audio and slew-rate effects
Quote:
Originally Posted by john curl View Post
The circuit you showed was typical of what was in 'Wireless World' at that time..
What was original at this time was the use of fast devices, for slew-rate, as i said. Everybody was using poor 2N3055 at this time.
This amp was using a stabilized supply with protection, and switched resistance arrays for volume and tone controls, like all mid-fi, isn't it ?
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Last edited by Esperado; 13th February 2013 at 05:40 PM.
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