John Curl's Blowtorch preamplifier part II - Page 1857 - diyAudio
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Old 1st December 2011, 05:16 AM   #18561
Bonsai is offline Bonsai  Taiwan
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John, forgive me jumping in here.
Maybe you would have got an 'A' on the JC3 IF the reviewer and others in the industry did not know you had used an op-amp! Remember that ML with the AD797 that got an 'A' rating . . .



ok - I know I am going to get flamed. I'm outa here!
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Old 1st December 2011, 05:57 AM   #18562
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Maybe, but I would not bet on it. I can only relate what I have experienced. In truth, my Vendetta Research phono stage is so much better than the JC-3, that there is little comparison. Of course, I own one.
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Old 1st December 2011, 06:16 AM   #18563
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Quote:
Originally Posted by abraxalito View Post
I have a hypothesis, FWIW - undegenerated bipolar inputs.
I agree - one of possible reasons.
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Old 1st December 2011, 06:19 AM   #18564
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Quote:
Originally Posted by john curl View Post
He also measured the AD797. It came out pretty good in differential phase.
I would respectfully comment that I do not assume the differential phase to be the reason of well subjectively accepted opamp.
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Old 1st December 2011, 06:28 AM   #18565
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This phono preamp situation reminds me of my position with my Porsche 944. I love my 944, BUT it is not that fast, just spunky. IF I had a 911 or one of its successors, perhaps I would put the 944 in the 'proper' perspective, a design made partly of VW parts, and many design compromises. BUT I don't have access to a 911, or a Boxter, AND I will never be able to afford one, so I am relatively happy with what I have, AND by comparison to the vast majority of autos out there, within my cost range, the Porsche 944 is the finest car I have ever owned.
I am sure that many customers for the JC-3 will be very happy with how it sounds, and its obvious advantages over many other, especially cheaper products.
I do not expect the customer for the JC-3 to be a newbie, but someone with some experience with other phono stages, yet not the very best, just like I am with sports cars, as the 944 is my 4th sports car that I have driven for at least 5 years. The others were fun, but they did have their limitations that I hardly noticed when I owned them.
Audio is much the same, in my opinion.
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Old 1st December 2011, 06:29 AM   #18566
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It's a start.
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Old 1st December 2011, 06:45 AM   #18567
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There were also publications about the differential phase shifts in interconnect cables
Current Dependent Phase Shifts in Audio Cables?
After simple analysis, the results were finally explained simply by L parameter (cable inductance effects). Audiphiles know, that simply low inductance does not automatically made cable good.
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Old 1st December 2011, 07:14 AM   #18568
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I have just read the Stereophile review of the JC 3. It is a very nicely built and very well measuring phono preamp, congratulations.

Time after time my customers ask me (I would rather say require) a phono preamp based on discrete components only, with JFET input as a must. I am still hesitating, though I have a design prepared in electrical drawings. It would be rather costly and I am not sure if my necessary expenditures would return in a sale of several pieces.
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Old 1st December 2011, 07:41 AM   #18569
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Quote:
Originally Posted by PMA View Post
Time after time my customers ask me (I would rather say require) a phono preamp based on discrete components only, with JFET input as a must.
Curious to know what's behind this request. Is it that they are unable to hear good sound when they know there's no JFET input stage in their phone pre? Otherwise the choice of input device is an engineering decision, to get the best sound at a particular price-point. Seems like your customers have a fashion request for JFETs, just as I used to prefer AMD 'Inside' rather than Intel.
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Old 1st December 2011, 07:58 AM   #18570
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Based on my experience with line level preamplifiers, the best sonic results I have achieved (even for me) are with JFET input, discrete, complementary symmetrical designs. So I am with John here. If the similar topology was with BJT input stage, the customers would always prefer the JFET version, even if they owned both of them. I do not want to turn any spirals again. To me, the JFET input stage is better sounding than the bipolar, even if they measure almost same. My explanation is the higher EMI immunity, though I may be wrong. Anyway, I will continue with the circuits that have proven well sonic accepted.

Regarding opamps, it is easy to make swap tests. You do not to and you would not like to inform the listener which opamp is tested. Despite this fact they can easily tell the differences, if they are experienced and trained listeners.
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