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John Curl's Blowtorch preamplifier part II
John Curl's Blowtorch preamplifier part II
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Old 9th March 2013, 03:22 AM   #36501
Bonsai is offline Bonsai  Europe
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Originally Posted by SY View Post
Depends. If one uses a panel of listeners and collects rankings along various "subjective" quality axes (e.g., "brightness," "clarity," "image specificity," that sort of thing), objective conclusions can be drawn about subjective impressions. These data are often presented in "radar charts." ANOVA is your friend here.

That's not very practical for low volume items made for niche markets, unfortunately.
Yes, I agree the best way to 'objectivize' a subjective issue like listener perception is to use some sort of numerical scoring method. Works in things like staff appraisals on the soft issues as well.

(I was also just trying be a bit of a smart *** )
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Old 9th March 2013, 03:25 AM   #36502
Bonsai is offline Bonsai  Europe
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George

So far I have only measured flux leakage. Still to be done is line noise pass through and AC balance.


The loser is the flatpak. The best may be r core and tortoid.

There is more than 2 millivolts across the chassis for the flatpak.
That's second from left in your pic? I would have thought the split bobbin would give quite a good result.
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Old 9th March 2013, 03:36 AM   #36503
simon7000 is offline simon7000  United States
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No it is the one on the bench
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Old 9th March 2013, 06:24 AM   #36504
1audio is offline 1audio  United States
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John Curl's Blowtorch preamplifier part II
Can you describe the test setup a little better? Some sketch of the different setups would help a lot. I'm not sure I understand what you are measuring.
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Old 9th March 2013, 10:10 AM   #36505
Joao@AltheaMusica is offline Joao@AltheaMusica  Switzerland
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Originally Posted by jan.didden View Post
You mean a controlled listening test with experienced listeners?
I believe John is against that.
jan
Jan, sorry for the late response. Yes I mean that. Getting some opinion from outside can open your sensitivity. As designer you have some blinders (that's normal)and therefore this can be helpful.

Listeners must not be audiophiles, it could be musicians - and best women (they listen more critical).

Think you're right John is not a friend of this.
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Old 9th March 2013, 10:21 AM   #36506
simon7000 is offline simon7000  United States
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Can you describe the test setup a little better? Some sketch of the different setups would help a lot. I'm not sure I understand what you are measuring.
If you look at the bench photo you can see the test leads connected to the chassis. They are on the same side of the transformer as the sheet metal. What is being measured is the voltage across the length of the chassis.

The transformer is measured 3 ways. First unplugged, then with AC but no load and finally with a load.

The load is shown. It is two diodes going to a 50 ohm resistor filtered with a 2200 uF capacitor. In the ground leg is a .1 ohm resistor that has a transformer load on the secondary by 72 ohms.
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Old 9th March 2013, 11:27 AM   #36507
jan.didden is offline jan.didden  Europe
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Originally Posted by Joao@AltheaMusica View Post
Jan, sorry for the late response. Yes I mean that. Getting some opinion from outside can open your sensitivity. As designer you have some blinders (that's normal)and therefore this can be helpful.

Listeners must not be audiophiles, it could be musicians - and best women (they listen more critical).

Think you're right John is not a friend of this.
Agree. Actually, arguably EVERYBODY has his blinders, not just the designers.
But I do not agree listeners must be musicians. It has been argued elsewehre that they pay far to much attention to the musical interpretation and not the actual reproduction, and I agree. Musicians, unless they are trained listeners to sound reproduction, are not advised for such a test.
Same argument goes for women - if they are traned listeners, fine, if not, not.
Judging sound reproduction isn't about the last half octave above 18kHz.

jan
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Old 9th March 2013, 01:14 PM   #36508
jacco vermeulen is offline jacco vermeulen  Netherlands
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Originally Posted by jan.didden View Post
Agree. Actually, arguably EVERYBODY has his blinders, not just the designers.
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Old 9th March 2013, 01:22 PM   #36509
john curl is offline john curl  United States
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Joao, I would appreciate it if you understood me better. OF COURSE, experienced musicians LISTEN and EVALUATE my products. They don't do it in the design process, how could they? But after the design is done, or even if the design is still a prototype, we will send a component out to music schools and such for evaluation. In fact, I am soon getting for my own use, a newly designed power amp that has been evaluated in just this way, and not only with other designer/audiophiles. We just sent another amp to Germany for independent evaluation.
However, personal approval from a symphony conductor or such will not cut much weight with this audience who think that virtually all good amps sound the same. ALL my amps and preamps measure very well, so many here think that they should sound the same as any other component that measures very well. It isn't my experience, but many here discredit my experience, as propaganda or hallucination. '-)
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Old 9th March 2013, 01:24 PM   #36510
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My kind of man! (and you will not be allowed to post here again )

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I won't but I will. My shortcoming is that when I listen to the stereo system, I can no longer hear the music.
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