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Comment about speaker cables/interconnects
On 7 Sep 2003 19:28:04 GMT, (Martin) wrote:
Much myth and techinal nonsense.
What does all of this have to do with audio cables you may ask.
Everything. Cables essentially serve as carriers of data.
Yes, but the definiton of data changes dramtically depending
upon the domain you are in.
Assuming as a baseline the bandwidth of a cd (44000*16bits per channel
= 704 kb/s) the amount of data being transmitted is very considerable.
Yes, and is fully encompassed, by its very definition, in a
continuous-represented signal whose bandwidth is approximately
20 kHz and whose dynamic range is around 96 dB.
You are confusing information content and data rate.
if one sample has a value of 5024 then that exact value must be what
is found at the other end of the interconnect/cable. If the value
recorded at the other end is 5024 +/- 1 then we are losing almost 2
bits of resolution on the sound or a drop in signal to noise of 12db.
Simply not correct.
Since the CD specification came from studies of human hearing this
loss of two bits is definetly noticable.
False, the CD specification did not come from staudies of human
hearing. The specifics of CD specification came from the
predominant storage medium used for mastering that predated the
CD, i.e., video recorders hooked to A/D and D/A converters
determined the sample rate of 44,100 samples/second, and 16 bits
is a convention that existed for data storage LONG before the
CD.
That the specification ALSO happens to allow storage of audio
over a bandwidth and dynamic range sufficient as a distribution
media satisfyinng auditory criteria is comething else.
Transmitting 704kb/s over a serial connection would be quite a trick.
Excuse me? It's done routinely all the time and has been done
routinely and without error for several decades.
It can be done but only if care is taken into the way that the signal
is transmitted. Obviously this represents a much lower data rate than
ethernet connection but we must also consider that the type of signal
is very different. Speaker cables and interconnects can't use
modulation of high frequency signels(measured in Mhz and gHz), Rather
the method of signal tranmission is more like amplitude modulation
with relatively low (measured in kHz) to extremely low frequencies
(measured in Hz), where microvolts may represent the difference
between 16 bits and 14 bits of data being transmitted.
Sorry, but this is just technical nonsense, and no disrespect is
intended. First, analog signals as you describe have been
trivially transmitted over substantial distances without any of
the problems you claim. Indeed, in the fields of biomedicine,
physics, chemistry and others, signals FAR more fragile than
what you are talking about here have been routinely propogated
error free over long distances under worse conditions than you
will find in domestic listening situations without the losses
you claim are inherent.
Second, you seem not to understand at all the difference between
a signal and the information content of the signal. The two do
NOT put the same demands on the transmission medium if you
switch form a continuous signal to its discrete representation.
The bandwidth for the latter is required to unambiguously
differentiate logic states.
With speaker cables the difference is even more profound. Not only
must the source generate this signals with considerable voltage and
current, but the speaker's themselves the recipients are also acting
as sources of noise being transmitted back down the line.
No, they are not. This is a very common, very pervasive and very
wrong myth on several fronts. First, where is the source of this
energy? The amplifier. The model you describe is simply the
behavior of resonant systems, be they electrical or mechanical.
A speaker does not act any more as a "noise generator" than does
a simply RLC resonant circuit, despite some stupendously
uninformed pronouncements to the contrary in the high-end press.
Second, even considering the speaker as an independent source of
noise, consider the Thevenin equivalent of its source generator
with respect to the effective load, i.e., the amplifier output,
where that source impedance is a half dozen ohms, and the load
is a small fraction of an Ohm. How much attenuation results?
I would
suggest that there is a significant amout of data distortion present
even when using the finest amplifiers with excellent short cables.
You may suggest all you want. "significant amount of data
distortion" is something that is trivial to quantify, yet no one
has EVER demonstrated such distortion exists. WHy? Becuase it
DOESN'T exist.
As I said I only begain thinking about this after noticing a huge
difference to the sound of my system after changing the speaker
cables.
Well, again with no intent at disrespect, your thinking has led
you quite far down the wrong path. Your explanation about data
rate that leads to the premise of data distortion is simply
contrary to the behavior of signals and cables.
Now I am just tring to come up with the theory to explain my
observations.
You have made a change and you seem to have noticed a
difference. You have a "theory" about "data distortion."
Fine. In order for a theory to be at all useful, it needs to be
testable. I am not going to argue with your observation that you
seem to have heard a difference, rather on your rationalization
of the difference. You claim something about "data distortion."
Well, if the signal IS so distorted, a simple null test will
either support or refute your theory's validity on its face.
SImply compare the input to the cable to its output with a
system whose smallest resolvable change is smaller than your
claimed distortion. If a difference is measured, then chalk one
up for your theory. If none is measured, it's a clear blow
against it.
Well, indeed, such measurements HAVE been made, and not a single
cable of even remotely competent construction has exhibited
differences even remotely approaching the levels you are
claiming. That would suggest your theory is wrong.
The confusion between information content and data rate itself
that is the assunmed basis for your theory is itself on very
shakey ground.
--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
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