Re: OT question about sound cards/chip-sets and high-end music systems
On 20091016_115141, ghe wrote:
>
> On Oct 16, 2009, at 9:50 AM, Paul E Condon wrote:
>
>> Analog signals degrade on long cable runs, particularly
>> the high freq. part of the signal.
>
> Not if it's low impedance balanced, it doesn't. Not at 100' anyway.
>
> Use the hardware Deutsche Grammophone, etc. use -- your recordings aren't
> going to sound any better than that...
>
> --
> Glenn English
> ghe@slsware.com
Impedance and balance are two different things. Impedance only becomes
an issue when the wave length of the signal on the cable becomes
comparable to the length of the cable run. Balance OTOH has only to do
with rejection of common mode environmental noise, e.g. hum pickup, not
with loss of signal amplitude.
In addition to impedance and balance, there is also hi-freq. loss due
to RC time constant of the cable. Cheap cables have small center
conductor, and thin layer of insulation. Small conductor is higher
resistance (R). Thin insulation is higher capacitance (C). Both make
hi-freq loss greater. I have never seen wire size/ insultation
thickness spec.s on the label of any audio cable in a consumer
electronics store. I have never seen balanced output of stereo audio
in a single jack on a computer. (An example of RC time constant
effects, is the difficulties CPU chip makers have with on-chip signal
timing. The wave length of the signal is vastly larger than the chip
size, but still the signal at the receiving end of a via rises
noticeable more slowly than at the sending end.)
But this is theoretical knowledge. It precludes me from believing much
of the marketing pitch of consumer grade electronics. I'm hoping to
find some practical information that is in better conformance the
established theory.
I'm older now than when I bought the hifi. Hearing declines with
age. But I can still tell the difference between the sound from my
computer and from my hifi. It may be that the age of real hifi has
passed, just as the age of the vacuum tube has passed, but I'm hoping
not (for real hifi. I don't mind the new dominance of transistors.)
Thanks for reading to the end of this rant.
--
Paul E Condon
pecondon@mesanetworks.net
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