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Old 22nd January 2002, 12:53 PM   #91
tiroth is offline tiroth  United States
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Quote:
Originally posted by JohnR You don't think that an amp will sound different with saggy rails than with "tight" rails? [/B]
Doesn't a well designed amp rely only on the rail ripples (or sag) being equal in magnitude? So rail sag (and ripple to a degree) affects amplifier performance only so far as limiting power to the onset of clipping.

Right?
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Old 22nd January 2002, 04:55 PM   #92
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Depending on the design of the circuit (current sources/voltage regulators in particular), it would change the operating point of the devices. Preamps and amplifier front ends, etc. might suffer disproportionately.

Grey
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Old 22nd January 2002, 05:07 PM   #93
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Default current pulses, etc.

If you guys are that worried about high current pulses and what that does to your line, amplifier, etc (and these are real concerns) then you ought to be running choke input power supplies. To further guild the lily, use a power transformer withan electrostatic shield between the primary and the secondary. And then use a dedicated 60 hertz line at least back to the circuit breaker box. A properly designed choke input power supply looks like a resistor to the 60 hz line. (Also see the SOZ choke input filter question in the Pass labs forum.) Running bear: My soldering iron is getting hot. Gotta go build something. See you guys later.
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Old 23rd January 2002, 04:00 AM   #94
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I don't see any mention of quantum physics yet... sounds like a good sales pitch (it is, isn't it?). Electron drift velocity is usually much slower than a few meters per second with a properly chosen cable, and stray capacitance has nothing to do with signal or current -- it is a function of the area between the two conductors and the dielectric constant of the insulation separating them.


Quote:
Originally posted by Joseph Cohen
Here's something I wrote for a line of cables I was at one time importing:

"Correctly designed cable is the primary and most critical means of insuring the proper delivery of the audio signal from source to loudspeakers. The general misconception is that audio cables are like hoses with the signal traveling inside them. In fact the flow of electrons within conductors is measured at a few meters per second, while the signal itself travels on the energy of the electromagnetic force surrounding the conductors at the speed of light. For this signal flow to be perfect and unimpeded it is necessary that the electromagnetic fields surrounding the conductors retain their symmetry, which is distorted by EMI, RFI and high frequency digital pulses and especially by stray capacitance which arises as a result of signal and current that runs on the shield and throughout all the cable's materials. Stray capacitance is the single greatest cause of coloration and distortion in audio cables."

So from my point of view we are already into quantum physics when we attempt to describe the forces at work in the behavior of signal transmission. This goes way beyond capacitance, inductance and resistance and into areas that are mostly beyond the capabilities of our most sophisticated measuring instruments.
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Old 23rd January 2002, 08:04 AM   #95
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Quote:
Originally posted by JohnR
Well, it's not just the output stage that is connected to those rails, so it's not simply a question of output power.

You don't think that an amp will sound different with saggy rails than with "tight" rails?
Sure thing, but again, unless the cable has a such small resistance that it becames insignificant, this just can't be avoided with an unregulated psu. Such is life.
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Old 23rd January 2002, 11:47 AM   #96
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Default Reality bites

If one is just talking about the 2 meters of powercord, this is an insane debate. Only at the extreme edge (powersupply for your powersuppy, direct connect to the streetmains, filterbanks, etc.) is this theory every going to come into play. One would be much better off chuncking all of that money into the best damn powersupply one could build.

BUT to take it to the absurd. (he he )... Many power companys are trying to put broadband down our electric wires. In the case of the switching powersupplies, will this little amount of high(er) freq. noise in the mHz. interact with those devices? It has to be at a higher level than the current RF noise that might be in the wire...
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