用PC+光纤+专业解码器能否达到HI-FI CD机的水平？？

haiying

交易区新帖推荐

这个问题问得听好的。
我想在编辑过程中，信息是以数字的方式存在并进行编辑，这没有什么问题。输出、输入的过程可能执行的是工业级的标准，有别于民用器材，当然我想价钱也应是工业级的。
仅仅是个人分析，如有在这方面比较了解的DX请指点。

haiying

我个人认为是可以被复制的。
而且用电脑也可以达到专业级的声音，但是价钱上没有折扣，如此下来，是不是单买一台CD机，再买一台PC，更经济呢？

念苍僧

反正我听过很多的电脑（包括很多笔记本）放的音乐。。。还没有一台能赶上CT790的效果的。。。。

念苍僧

反正我听过很多的电脑（包括很多笔记本）放的音乐。。。还没有一台能赶上CT790的效果的。。。。电脑放的音乐除了推力比现在出的CD随身听大以为，我认为还不如随身听。。。一点音乐味都没有。。用音箱听还凑合，用耳机。。。算了吧。。。

念苍僧

那你不是想自制转换电路解码器什么的吧。。。。

gene

[B]又是这个数字信号能不能被完美复制和传输的老问题[/B]

数字音频涉及的远不止上面这些。取样、量化、编码、存储、传输... ...

用PC做高档音源是舍近求远。

详细讨论需要一些知识基础，附一篇可谓简洁的相关文章。慢慢看吧。

A very common misconception about digital signal
transmission with respect to audio is that if the signal does
not get corrupted to the point of losing or changing the 1&#39s
and 0&#39s, that nothing else can go wrong. If the transmission
system had been designed with cost no object, and by
engineers familiar with all the known foibles and problems
of digital transmission of audio signals, then this might
be subtantially true. No differences could rear their ugly
head.

Unfortunately, the systems we ended up with DO NOT remain
unaffected by such things as jitter, where the transistion
from a 1 to a 0 is modulated with respect to time. There are
many ways that jitter can affect the final digital to analog
conversion at the DAC. Jitter on the transmitted signal can
bleed or feed through the input reciever, and affect the DAC.
How? Current drain on the power supplies due to the changing
signal content and the varying demands made on the power
supply to the logic chips and the DAC. Modulate the power
supply rails, and the DAC will convert at slightly different
times. HOWEVER the power supply gets modulated, it will
affect the DAC. One version of this has been popularly
refered to as LIM or Logic Induced Modulation by the
audiophile press. See:
"Time Distortions Within Digital Audio Equipment Due to
Integrated Circuit Logic Induced Modulation Products"
AES Preprint Number: 3105 Convention: 91 1991-10
Authors: Edmund Meitner & Robert Gendron

Many of the logic chips in a digital audio system behave
very poorly with respect to dumping garbage onto the rails
and even worse, onto the ground reference point. Even as I
post, logic manufacturers such as TI are advertising the
benefits of their latest generation of logic chips that
reduce ground bounce. The circuitry itself generates it&#39s
own interference, and this can be modulated by almost
anything that also affects the power supply or ground.

Who cares what the power supply rails or the ground is doing?
The DAC cares, beacuse it is told to convert a digital signal
value at a certain time. This time is determined by the master
clocking oscillator in some designs, and in others by the
digital data stream itself by deriving a clock from the clock
data embedded in the data stream, and when the DAC
has determined that a
transistion from logical one to a zero, or a logical zero to a
one, has in fact occured. The point at which the DAC decides
this has occured, depends on the absolute value of the power
supply rails near the moment of detection/conversion. The purity
of the master oscillator signal is also affected by PS and ground
variations, as well as sound vibrations, and the activity of the
various subsystems within the CD player/DAC box. If this master
oscillator signal is not perfectly pure, and free from noise, phase
jitter, and other artifacts, then even if the DAC was totally
unaffected by PS perturbations (virtually impossible to accomplish),
then the master oscillator signal itself would cause jitter.

The amount of jitter that it takes to affect the analog
output of the signal used to be thought of as fairly high,
somewhere on the order of 1,000 to 500 pS worth. Now, the
engineers on the cutting edge claim that in order for jitter
to be inaudible and not affect the sound of the signal, it
may have to be as low as 10 to 20 pS. That&#39s for 16 bit
digital audio. That&#39s a very tiny amount of jitter, and
easily below what most all current equipment is capable of.

Computer systems never convert the 1&#39s and 0&#39s to time
sensitive analog data, they only need to recover the 1&#39s
or 0&#39s, any timing accuracy only has to preserve the bits,
not how accurately they arrive or are delivered. So in this
regard, computer systems ARE completely different than
digital audio systems.

Look into digital audio more thouroughly, and realize that
the implementations are not perfect or ideal, and are
sensitive to outside influences. Just because they could
have been and should have been done better or more nearly
perfect does not mean they were! People are not hearing
things, they are experiencing the result of products designed
to a cost point that perform the way they do in a real
world because of design limitations imposed by the consumer
market price conciousness all the mid-fi companies live and
die by.

Jitter read from a CD will affect how well the read servo
stays locked, and how much the read servo has irregular power
supply demands. Just about everything and anything affect the
power supply, so reduce jitter read from the disc, and it will
affect the accuracy of the playback event.

With digital cables, there are three things that are paramount:
proper impedance, proper cable termination, and wide bandwidth.
It may be that a particular cable more nearly matches a systems
actual impedance. The other factor, proper termination includes,
but is not limited to the actual electrical termination inside
the components, as well as the connector on the end of the
cable. If the connector is NOT a perfect 75 ohm, 110 ohm, or
whatever, it will cause minor reflections in the cable, which
makes our old friend JITTER raise it&#39s ugly head again.

The third factor, bandwidth, is only an issue because both the
AES/EBU and the SP/DIF interface formats were designed before
Sony/Phillips knew all there was to know about digital problems, and they
require PERFECT unlimited bandwidth cables in order for the
transimission systems to be free of jitter. The more you limit
the bandwidth, the more jitter. This is a known engineering
fact, and an AES paper was given about this very subject not
too long ago.
"Is the AES/EBU/SPDIF Digital Audio Interface Flawed?"
Preprint Number: 3360
Author: Chris Dunn
Author: Malcolm O. J. Hawksford

The effective data rate of SP/DIF is about 3 Mhz, and the
design of the transmitters and recievers is abysmal. Maybe
if everything else was done right, then cables, etc. wouldn&#39t
matter. So much was done wrong or cost cut till it screwed
up that they do come into the picture.

hyperma

这方面,在上海PCHOME里有许多人在讲,看看挺好的.

山海经

太专业的东西我不懂，我只知：做高档cd的明知做电脑的发展快还投入那么多精力去开发和研究。难道就是为了艺术不赚钱。

电视

在你们眼中PC=CD？
那LD怎么算，算LP/VCD/CD，还是PC。