Heaven forbid we talk about crimp connections. Once the wire touches the rest of the bundle the "openness" ceases, lets not talk about micro-diodes again.
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I'm always excited when I hear of stuff done since I went bush but am invariably disappointed. Loads pontificating but where are the Listening Tests especially on speakers? Even pseudo prophet Floyd does little but confirm Peter Fryer's work from 70/80s.
When you start trying to confirm some of this with Listening Tests, you immediately come across unexpected stuff like, "dis dun sound like speaker distortion at all" or "why is does dis with low measured distortion 'sound' more distorted to the Listening Panel" and "All dem self declared Golden Pinnae are deaf !" If you don't do Listening Tests, you start chasing unimportant stuff while the really audible stuff is staring you in the face.
A Listening Test is a measurement. Your instrument is your Listening Panel. The instrument has an accuracy which needs checking and calibration every now & then.
I don't buy "JC Maxwell (or Washington or other famous name) says it has Unobtainium and is made by virgins so it must be good."
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There are good reasons why Rice & Kellog's invention is still dominant after nearly a century.
I'll put up certain moving coil speakers against any other technology to win by a wide margin on music in a properly conducted Blind Listening Test. Yes, it distorts but in less important areas than any other technology.
For it's remaining distortions, I'm really a speaker man. I've chased 1ppzillion THD in amps but to me, an amplifier is just a crossover component so I begrudge anything in a power amp if doesn't improve amp/speaker. eg an extra stage may reduce THD from 0.01% to 0.001% but often makes the amp more susceptible to instability with certain speakers. Many (all?) Golden Pinnae amps are guilty of this.
Mr. Curl, which Levinson 1980's power amps were you involved with ?
I posted this in another forum.
>For what it is worth, I think this is impossible. It seems to violate the cause and effect principle. How could the amplifier "know" what the speaker is up to? Short of sensing the actual motion of the drivers or the actual sound... this has to be sort of by guess and by golly, it seems to me.
It is entirely possible for an "amplifier" to know what the speaker is doing.
It needs to sense the speaker current. An amp which twiddled its Output Z using both current & voltage feedback does this. Speakers act as accurate microphones (sense the actual sound) if operated into Low Z.
See "Loudspeakers as Microphones" - Peter Baxandall special lecture London AES (early 80s, late 70s?)
If operated into High Z, then the voltage at the terminals is a measure of cone velocity.
Both these mechanisms obey superposition & Thevenin so if you're clever, you can look at this while the amp is giving zillion volts and amps to the speaker. But non est tantum facile.
There are several tried & tested methods of using this "controlled output Z" or "current + voltage feedback" or "actual sound & motion feedback" (different descriptions of the same thing) if you incorporate the amplifier design in the speaker. Some of these are in the zanier incarnations of my Powered Integrated Super Sub technology.
The simplest is the negative output R that Fons mentions.
More sophisticated but similar (??!) is ACE technology by Erik Stahl which was used by Audio Pro, Sweden for subs. Unfortunately, since he left, there isn't anyone there who understands it. Anyone have a contact for Erik? Or a clean copy of his original AES preprint?
These methods have the distortion reduction and dynamic overload protection features discussed in Mills & Hawksford. However, they are badly affected by heating of the voice coil.
David Birt did an excellent IoA paper at Windermere where he arranged speaker and amp in a bridge so he could measure and compensate for heating on the fly. Anyone have an email for him?
These are the most elegant methods and they can be analysed from many viewpoints. Some of these viewpoints don't show up the distortion reduction advantages clearly.
I'm contemptous of methods which rely on extra transducers or extra windings (like Mills) or zillion point DSP EQ especially if they don't give ALL the advantages of the elegant methods.
A brute force zillion point approach possible today is measure accurately speaker Z (not that easy) and tailor the output of a High Z amp to suit. This would give some but not all the advantages of the above systems cos it wouldn't "know" what the speaker is up to.
Meaning that micro-diodes don't exist, or are irrelevant, can't have any audible effect if they do exist?
And, if two pieces of metal touch, we then have a perfect connection, can be modelled in Spice as a straight line? I do note that there are such devices as metal oxide - metal diodes, used for doing real things ...
Frank
Thanks for the warning George but I'm perfectly aware of JC's reputation though I have been out of circuit for more than a decade. I think the best summary is the reply he posted to Bob Cordell about how 'proved' zillion V/us and I second Bob's opinion in his reply.Mr Curl has not stepped back in real-life hard confrontations.
He has proved that he has courage. Do a reading of his professional life.
I'm waiting to see if he bites and who he is offering for the Blind Listening Test panel. This is of considerable interest to me as my list of self declared Golden Pinnae who aren't deaf is very short; in fact empty after nearly 2 decades of conducting these tests.
You could also accuse me of making outrageous statements without having to bankroll the forfeit if the results go against me as I'm presently destitute ... and you'd be right
But seriously, what I'm trying to show is that it is possible to devise a Blind Listening Test that meets ALL the objections of the Golden Pinnae.
Persuading JC to participate, which is a considerable investment for him with no possible advantage & big -ve consequences possible is another matter. There's where the courage lies.
But if he bites, I'll have to see whether John Atkinson remembers a mad Chinaman. The Dynamic Duo already know rumours that I'd been eaten by a crocodile are false.
Anyone know of Blind Listening Tests which involved JC or his designs?
And Mr. Curl, I'd still like to know the 1980's Mark Levinson amplifiers you designed. Just to tidy a loose end from the previous millenium.
I would be interested in any studies that have attempted to understand "bad" connections, in reference to audio performance. People frequently cite gold to gold as doing a "good enough" job -- try telling that to an old PC I once had in a seaside environment, that started getting dodgy. Pulled it apart, and was impressed by the green muck coating the gold contacts everywhere. Of course, all gold coating used in audio gear is far superior, so we don't have any worries ...
Frank
Frank
John has talked about them repeatedly. He couldn't hear the wonderful things he could hear when peeking, so his excuse then was that the tests were flawed.
His excuse now is that he's old and can't hear the things he could hear when he was younger, or at least not as quickly.
I'm not worried about the signal itself, I'm worried about that faulty strand acting as an input for external interference. To take it to a "purer" level, consider the overall cable to be Litz, single broken strand at one end. Bring a strong RF source deliberately very close to the cable: will there or will there not be any pickup?
Frank
I know that strands of copper will oxidize and thus create issues of strand-to-strand effects (weak diodes?). Its the main reason to go to oxygen free copper wire(s). That and the effects of the oxide (semi-conductor) on the surface travelling part of the signal - on skin depth signals. I dont know of the specific listening consequences of oxide but would rather avoid it, just in case -RNM
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what is the mutual inductance, capacitance of this broken stand with the rest of the cable - pretty High for both I would guess
how well shielded from the hypothetical interfering wave, how poorly differentially coupled vs the rest of the cable - I don't have numbers but I'm not alarmed so far in the chain of assumptions
No evidence anywhere for this imaginary demon. Internal differences of tenths of a volt while the bundle as a whole maintains low ohmic connectivity? Why not apply some common sense first?
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I would like to have your faith,
! Dealing with these issues has driven me mad over the years, my ears have told me what works and what doesn't, and it has been repeatable enough to satisfy my "inner scientist", many times over. Unfortunately, these are the true "devil's in the details" areas that make or break the sound of a system, irrespective of cost, IME ...
Frank
I would like to have your faith,
Unfortunately, these are the true "devil's in the details" areas that make or break the sound of a system, irrespective of cost, IME ...
Frank
You're a smart guy step back and actually enumerate the things that have to happen to make these effects exist.
The effects do exist, but what they're caused by is another matter; I certainly know degradation of metal to metal contacts with time, as in the normal method that audio components are linked, has a damaging impact. One of the first major excursions into tweaking, decades ago, was to eliminate every poor quality contact throughout the setup, and I couldn't live with a system where I couldn't do that.
My positing of diodic behaviours within the cable is just an extension of that, I'm happy to be aware of rigorous "proof" about why it can't happen, so long as it isn't of the arm waving type ...
Part of this is because I have no trouble hearing the impact of RF; also, I have come across enough discussion by Ott of how remarkably easy it is for a sole piece of metal or wire to act as an antenna, to just dismiss such factors out of hand.
Frank
My positing of diodic behaviours within the cable is just an extension of that, I'm happy to be aware of rigorous "proof" about why it can't happen, so long as it isn't of the arm waving type ...
Part of this is because I have no trouble hearing the impact of RF; also, I have come across enough discussion by Ott of how remarkably easy it is for a sole piece of metal or wire to act as an antenna, to just dismiss such factors out of hand.
Frank
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Never listened any wire 'behavior" that cannot be *measured* and explained by the Ohm law in AC... or caused by anything else than electronic source or target imperfection, like overshoot of square waves, reduced slew-rates, phase changes etc. due to closed loops poles in source amp, source amp impedance, non linear parasitic caps in input stages.
Behaviors of cables can always be reproduced by coils, caps and resistances, simulating wire's characteristics.
Never measured or listened any change in wire behavior due to "burn-in" when temps and humidity are within atmospheric ranges.
Never measured or listened any effect of isolation material, other than changes in Capacitive values *in the audio range* with short wires. (Dielectric losses ? Order of magnitude ?)
Never measured any effect of surface corrosion (unless very oxyded cables under water), if connections are good.
Never measured differences between coper and silver other than impedance changes due to their diameter, lengths and conductivity. If silver is better for tweeter coils, it is just because it conduct better (less diameter for same resistance) and is lighter, so, less inertia. Just a mechanical effect. My 1GB network cables are made from coper and respect transmission lines theory.
As doctors have a responsibility to not let snake oil vendors propagate fake legends, i think those of us with some knowledge in electronic or physic have a responsibility to not let propagate implausible ideas like a wire can have a preferred sens when traversed by an AC signal where electrons travels in one direction during half a period and the other during the second half. (As Scott underlined).
As i feel very uncomfortable to read such things under the authority of somebody like John Curl, i ask technical explanation, numbers, and measurements.
Of course, we can talk of dynamic caps changes due to vibrating effects between conductors... Order of magnitude ? Common sens !
Behaviors of cables can always be reproduced by coils, caps and resistances, simulating wire's characteristics.
Never measured or listened any change in wire behavior due to "burn-in" when temps and humidity are within atmospheric ranges.
Never measured or listened any effect of isolation material, other than changes in Capacitive values *in the audio range* with short wires. (Dielectric losses ? Order of magnitude ?)
Never measured any effect of surface corrosion (unless very oxyded cables under water), if connections are good.
Never measured differences between coper and silver other than impedance changes due to their diameter, lengths and conductivity. If silver is better for tweeter coils, it is just because it conduct better (less diameter for same resistance) and is lighter, so, less inertia. Just a mechanical effect. My 1GB network cables are made from coper and respect transmission lines theory.
As doctors have a responsibility to not let snake oil vendors propagate fake legends, i think those of us with some knowledge in electronic or physic have a responsibility to not let propagate implausible ideas like a wire can have a preferred sens when traversed by an AC signal where electrons travels in one direction during half a period and the other during the second half. (As Scott underlined).
As i feel very uncomfortable to read such things under the authority of somebody like John Curl, i ask technical explanation, numbers, and measurements.
Of course, we can talk of dynamic caps changes due to vibrating effects between conductors... Order of magnitude ? Common sens !
Bob Cordell's recent (and excellent) book makes a suggestion that others may have already known, but that was new to me. If worried about parasitic reactances in a long speaker wire, include an appropriate Zobel at the speaker end. Cheap peace of mind. Obvious after ya hear it.
He also recommends one at line level inputs, maybe 75 Ohms and 100pF. I can't recommend the book too highly.
Thanks,
Chris
He also recommends one at line level inputs, maybe 75 Ohms and 100pF. I can't recommend the book too highly.
Thanks,
Chris
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