John Curl's Blowtorch preamplifier part II - Page 3311 - diyAudio
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Old 20th January 2013, 08:42 PM   #33101
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I'm a fet input kind of guy! '-)
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Old 20th January 2013, 08:44 PM   #33102
SY is offline SY  United States
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Quote:
Originally Posted by simon7000 View Post
Now I see the source of confusion. The Equivalent Series Inductance (ESL) of most electrolytic capacitors is measured at .5 Volts AC RMS 100 or 120 Hz.
Bad assumption. Start with that and nothing else will be correct. ESL is commonly measured by plotting Z vs f and seeing the resonant frequency. You check it by extrapolating the upward part of the curve to the f axis. That's how the plots in Jones and my own measurements are generated.

Yes, if you lay things out badly or measure poorly, you'll see worse numbers.
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Old 20th January 2013, 08:44 PM   #33103
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Levinson JC-2 from 1973:
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Old 20th January 2013, 08:54 PM   #33104
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Originally Posted by elektroj View Post
Stop trolling, guys ...
Did-you mean the Blowtorch thread has to die ?
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Last edited by Esperado; 20th January 2013 at 09:03 PM.
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Old 20th January 2013, 09:30 PM   #33105
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Ow, let's keep it going! '-) I know that some people would like to see it go, but how can we have such fun?
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Old 20th January 2013, 09:53 PM   #33106
fas42 is offline fas42  Australia
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Last call on the music thing. When I first got into the CD music scene it was "shock" after "shock" buying favourite albums, and the sound being so different from how I remembered it. But, the realisation and understanding came in quite some time ago that at least a major part of the answer was that I had so much more access to what was the "real" recording, being able to hear into the studio so much further. Recordings which I had originally thought spectacular seemed very manipulated, and others which had been relatively straighforward, or cluttered, became marvellous soundscapes.

Got over that years ago, automatically assume that a "familiar" recording will in fact be a whole new experience, it's a journey of discovery every time ...

Frank
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Old 20th January 2013, 10:03 PM   #33107
fas42 is offline fas42  Australia
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While i'm not able to hear any obvious difference in my system between my preamp (Ic based) and a short wire, i do not ask myself questions about any evils.
Nearly every time I listen to an expensive, or pretentious system I can hear plenty of "evil", and it has nothing to with -200dB levels of 7th harmonics. To pull a car analogy, it has to do with trying to drive a Ferrari with flat tyres; there are major problems with the setup as a whole, and minor inconsistencies are blown away in the face of the "big" issues ...

Frank
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Old 20th January 2013, 10:31 PM   #33108
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I totally agree with both of your messages, fas42.
About recording and mixing, it was the poor quality of the audio chain (including studio stuff) witch brought us to manipulate the sounds so much. With digital, and even with the same 'production climax' goal, i would be a lot less intrusive, today. As the pleasure can be in the instrument itself, if it is good sounding enough and well played.
About so called 'high end' systems, i often run away very fast with a grimace from the demonstration rooms, sometimes very impressive, with no connection to the reality...
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Old 20th January 2013, 10:58 PM   #33109
RNMarsh is offline RNMarsh  United States
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Bad assumption. Start with that and nothing else will be correct. ESL is commonly measured by plotting Z vs f and seeing the resonant frequency. You check it by extrapolating the upward part of the curve to the f axis. That's how the plots in Jones and my own measurements are generated.

Yes, if you lay things out badly or measure poorly, you'll see worse numbers.
This is quit true.
In addition: For smaller values which are harder to measure the Ls and esr, you can charge the cap to 1-5vdc and then short the leads together (with shortest distance/lead length possible). Dont do this with a large value cap - the currents will be extream and can heat the cap and damage it. Then pick up the current signal flowing in the Cap leads via inductive probe. You will see a ringing waveform with a decay. The freq of the ringing is the natural resonance freq of the cap with that amount of lead length and internal Ls. The oscillatory decay rate depends on the bulk resistance and the esr. Knowing the value of C and freq of ringing you can calculate the Ls.

Better is to do same test with cap on (empty) pcb with trace and wires attached.. obviously the resonance in-circuit will be lower and total Rs (including esr) also higher and that is all that really counts.... performance in-circuit... not what a cap does all by itself. [a superior cap measured out of circuit can become the worst cap with added Ls and Rs of circuitry to/from the cap.]

-RNMarsh

Last edited by RNMarsh; 20th January 2013 at 11:17 PM. Reason: Cap resonance in-ciruit -
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Old 20th January 2013, 11:22 PM   #33110
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we do have an active thead showing PS C Z measurements Network Analyser Measurements
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