John Curl's Blowtorch preamplifier part II - Page 3003 - diyAudio
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Old 27th November 2012, 02:45 PM   #30021
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Let me try again:
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Old 27th November 2012, 02:45 PM   #30022
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Quote:
Originally Posted by Steve Eddy View Post
Make that two. Cough, cough, John, cough, cough.

se

Make that three

George
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Old 27th November 2012, 02:57 PM   #30023
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Originally Posted by jneutron View Post
Here's the pic.
No ground at all is better, isn't ?

What is have done: replace my preamp AC wire with a big AC one. I use-it as the unique ac ground connection to the outlet. Tried the two senses of AC wires to get the less voltage betwwen ground wire and ground outlet before connecting grounds. Then connect my amp with no ground connection, find the best sens between the two chassis for minimum leakage voltage too. My signal wires does not connect ground, i have a big wire between the 2 chassis, following my signal cables. Then all parts connected to the preamp are tested for the sens in the same manner, and no ground connected to outlets.
All my signal wires shields have their ground connected only at the source part, with a ferrite near the plugs. The wires are on pair, and the cold wire connect the grounds.
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Old 27th November 2012, 02:57 PM   #30024
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Mostly, it's the recording and mastering; the playback gear has much less to do with it. With the few really good recordings out there, you get exactly what you're supposed to and the sound can be terrific. With other ones... well... you get the sound the producers intended with no low resolution media to plaster over the cracks. That may not be to your liking- it's certainly not to mine.
It is definitely not only the recording and mastering.
Indeed, the majority of the recordings from the last few decades are crappy, however, good recording and mastering sound crappy on most digital gear. The digital gear that sound really good (with good recording and mastering) is rare.
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Old 27th November 2012, 03:02 PM   #30025
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They do not.
Only the last stages: DACs.
My experience is that everything matters, not only the DAC section. See my experience with AMR CDP serving as a DAC and OPPO serving as a transport.

It should make sense. Nothing can sound better than what it is being fed with. Feed gold with crap, and you'll get crap.
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Old 27th November 2012, 03:02 PM   #30026
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1.0 - 1.8 V/us opamp with high LF voltage noise is suddenly good enough?? Wow, what a change!
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Old 27th November 2012, 03:07 PM   #30027
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Sounds that the designers of the AMR have learnt a thing or two.
Indeed.
The designer of AMR is Thorsten Loesch.

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Originally Posted by fas42 View Post
My suspicion is that the power supply of the Oppo is what's causing problems here ...
My assumption that it isn't only the power supply. The clock for the transport matters, as well as interference isolation, or lack of, between various circuits.
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Old 27th November 2012, 03:13 PM   #30028
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Originally Posted by john curl View Post
4558, well that restrained the discussion, didn't it? Scott, are you not prepared to DEFEND the use of the 4558, even with serious audiophiles? '-)
Unfortunately, even Ron Quan's tests still have a fairly high residual, that keeps us from evaluating the 'better' op amps completely, as their FM distortion (if any) lies below the residual of Ron's test equipment. Don't worry, improvements will be made. Maybe, a BIG company will address the issue and give us serious test equipment to measure this distortion. I sure would hope so.
4558 can't use 'em , we don't make them anyway. Ron's tests would probably yield to a digital solution with a high quality A/D and enough raw data.

Now address the point that highly regarded class A amplifiers have lots of PIM well above Ron's noise floor, and then go back and say again his test needs more resolution. This is just making no sense.
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Old 27th November 2012, 03:15 PM   #30029
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Can someone explain me this sudden interest in this poor poor 4558, that I would not use more than any TL0.72 for audio or even NE5532 ?
Very high slew rates and current feedback make all the difference between a dump system and an other, fast like light, transparent and light like air, on my point of view.
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Old 27th November 2012, 03:18 PM   #30030
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Originally Posted by Esperado View Post
No ground at all is better, isn't ?

What is have done: replace my preamp AC wire with a big AC one. I use-it as the unique ac ground connection to the outlet. Tried the two senses of AC wires to get the less voltage betwwen ground wire and ground outlet before connecting grounds. Then connect my amp with no ground connection, find the best sens between the two chassis for minimum leakage voltage too. My signal wires does not connect ground, i have a big wire between the 2 chassis, following my signal cables. Then all parts connected to the preamp are tested for the sens in the same manner, and no ground connected to outlets.
All my signal wires shields have their ground connected only at the source part, with a ferrite near the plugs. The wires are on pair, and the cold wire connect the grounds.
The intent is to eliminate any bouncing of the reference node the amplifier sees. Your technique is certainly viable, but my concern is that safety.

If your amp line-in hot hits chassis, will the path through the pre be sufficient to clear a 20 amp breaker? If not, the possibility of the entire system going hot becomes non-zero.

I note you put the grounding conductor with the IC's, that is very good. If you put the IC's within the grounding conductor, that would be even better. A cylindrical shell of current has no internal magnetic field. (see pic, it is a cross section of the magnetic field of a cylindrical conductor formed by hundreds of individual wires..I limited it to roughly 1/4 of the cylinder due to processor speed, but it shows what happens quiet cleary). If the IC's were routed within a copper pipe or a length of pex with a braid over it connecting the amp and pre, the IC's would have a path which will not see any ground loop magnetic field, there would be little RF intrusion.

The issue would be one of making sure the ground is reliable for life...both equipment's and humans.

jn
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Last edited by jneutron; 27th November 2012 at 03:21 PM.
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