John Curl's Blowtorch preamplifier part II - Page 2444 - diyAudio
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Old 13th July 2012, 08:00 PM   #24431
DF96 is offline DF96  England
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If you want no ringing you probably need a linear phase filter. Note that ringing does not necessarily mean the filter is adding anything, as ringing can occur by subtraction. Nothing to do with distortion, anyway. Our ears are quite good at hearing one issue and blaming something else. No reason why our brains should follow.
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Old 13th July 2012, 08:36 PM   #24432
bcarso is offline bcarso  United States
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Quote:
Originally Posted by DF96 View Post
[snip] Our ears are quite good at hearing one issue and blaming something else. No reason why our brains should follow.
An outstanding example of this, in my opinion, is the complaint about negative feedback "blurring details" and those who claim to hear "the dog chasing its tail".

In fact, I think many who prefer "open loop" systems and attribute their preferences to the lack of feedback are in fact hearing ringing in underdamped systems and structures and imagining this as constituting greater detail, "realism", and so forth. It is a situation somewhat analogous to listener preferences for a certain amount of room boundary effects and early reflections. If not done to death it actually improves sensory/perceptual acuity.
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Old 13th July 2012, 09:08 PM   #24433
DF96 is offline DF96  England
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Also people adding little antennas to their grounds to 'improve detail'. Injecting a little RF noise will change the sound, but not necessarily for the better.
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Old 13th July 2012, 09:12 PM   #24434
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Quote:
Originally Posted by bcarso View Post
An outstanding example of this, in my opinion, is the complaint about negative feedback "blurring details" and those who claim to hear "the dog chasing its tail".

In fact, I think many who prefer "open loop" systems and attribute their preferences to the lack of feedback are in fact hearing ringing in underdamped systems and structures and imagining this as constituting greater detail, "realism", and so forth. It is a situation somewhat analogous to listener preferences for a certain amount of room boundary effects and early reflections. If not done to death it actually improves sensory/perceptual acuity.
No reason to speculate on mechanisms until there is an agreement on what is heard that is not anecdotal. It will never happen, too much to lose on both sides.
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Old 13th July 2012, 09:59 PM   #24435
bcarso is offline bcarso  United States
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No reason to speculate on mechanisms until there is an agreement on what is heard that is not anecdotal. It will never happen, too much to lose on both sides.
Ah yes, too much to lose. Yet I still search for ways to reconcile the persistent reports. At least in the realm of loudspeakers and rooms, which tempted me to the analogy, there is well-documented testing that show significant preferences.

The principal apostle of feedback (if one likes, "excessive" feedback) being bad, selected examples of bad designs to "prove" his hypotheses, according to Zanfino and R. Miller. And we were off to the races.
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Old 13th July 2012, 10:45 PM   #24436
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Ken Newton, you again ask a perceptive question. All that I can easily answer is that I tend to recommend passive parts that have worked sonically well with my own designs as well as others. For example, Rel. Caps. Peter Moncrieff originally found them, and got the manufacturer to put copper leads on them, and they were called 'Wonder Caps'. They have been used almost exclusively in: the JC-80 preamp, Vendetta Research, Parasound, and Constellation. They are/or have been used in models of Ayre, Audio Research, and at least a dozen other high end audio manufacturers.
We have all known Bas Lim the owner and cap designer at Rel. for about 30 years. Charles Hansen found the company so valuable, that he offered to buy the company, to keep it in operation, if Bas ever retired (he is older than Charles and I are).
Dick Marsh worked with Bas to develop a unique capacitor that made the cover of an engineering magazine, at least once, as the optimum device for switching power supplies. The design was patented, as well.
Yet, critics of mine, like Scott Wurcer has apparently never heard of the company. Go figure! '-)
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Old 13th July 2012, 10:49 PM   #24437
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I use feedbacks with great pleasure. And with great results.
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Old 13th July 2012, 11:50 PM   #24438
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I hope that Richard Marsh will fill in the areas that I have to leave blank, but Rel. makes a number of capacitors for industry. Bas takes pride that labs and serious industry buys his product. It's his job to make good caps, and he takes his job seriously. He has TRIED to talk me out of some extremely expensive caps, never pushes me toward a cap that I have not chosen, and helps, the best he can, with problems that we might have with his caps, and others, by the way. A true engineer.
In my CTC Blowtorch Vendetta phono stage, we use Teflon 0.1uf and 0.047uf caps. That is what I use for EQ caps. I moved UP from Rel RT polystyrene, and I am pretty sure I heard a difference. However, today, I will probably design with polystyrene, rather than Teflon for my best designs. The Parasound JC-1, JC-2, and JC-3 have Rel. RT polystyrene caps in the power supply and the JC-3 uses .047uf caps for the RIAA Eq. All three designs have an A rating in 'Stereophile' All use global negative feedback, as well.
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Old 13th July 2012, 11:52 PM   #24439
RNMarsh is offline RNMarsh  United States
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Geeez did you guys miss the point? I am talking about test equipment measurements which correlate better than freq response or thd. It seems to have gone right over the heads of the readers here.
We are often told -- that because the thd or phase or freq response is super good, listeners are nuts to hear what they say they hear. It started with caps but I moved on to other areas.... you guys are still on caps and distortion? You are making yourselves look bad. -RNM

Last edited by RNMarsh; 13th July 2012 at 11:58 PM.
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Old 13th July 2012, 11:55 PM   #24440
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Good input, Richard.
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