I changed a CD Player in my PC today and forgot to hook up the wire (for
sound) that goes from the back of the cd player to the sound card, but I
still
was able to hear music when I put a music CD in. So what is the purpose of
this wire if I can still get sound without it being connected to the
soundcard??
On Jul 25, 7:34 am, "don" <d...@panix.com> wrote:
> I changed a CD Player in my PC today and forgot to hook up the wire (for
> sound) that goes from the back of the cd player to the sound card, but I
> still
> was able to hear music when I put a music CD in. So what is the purpose of
> this wire if I can still get sound without it being connected to the
> soundcard??
don wrote:
> I changed a CD Player in my PC today and forgot to hook up the wire (for
> sound) that goes from the back of the cd player to the sound card, but I
> still
> was able to hear music when I put a music CD in. So what is the purpose of
> this wire if I can still get sound without it being connected to the
> soundcard??
>
The old wire method, is analog audio in stereo from the CDROM. The CDROM
has a CODEC in it, for converting music files to analog. The four pin
connector carried stereo signals, suitable for differential amplifiers
on the computer sound chip. (By taking the difference, any common mode
noise on the CDROM wire pairs is removed.)
Currently, all that adding the CDROM wire does, is act as an antenna,
picking up electrical noise, that pollutes the noise floor of the
sound subsystem.
The current mechanism for CD music playback, is DAE or digital audio
extraction. That is an option in Windows which you can enable. Since the
music is digital samples recorded in the CD, it is just a matter of
reading a block of them, and having that travel across the IDE ribbon
or SATA cable. There should be less noise involved, because the music
is digital until it is eventually delivered to the sound chip.
Some optical drives have another kind of output, a two pin one, and
that one is a digital method. I've never found a spec for it,
and someone mentioned it is a high level SPDIF signal. I've never
read a description of how that interface would be used. It is possible
that the signal cannot be connected to SPDIF_in, even if a computer
had an actual working SPDIF_in connector. (I have computers here with
a connection, but they don't work.) The signal on the two pin interface
might not be standard SPDIF in nature. It might be TTL logic levels
for example.
On 2008-07-25, don <don@panix.com> wrote:
> I changed a CD Player in my PC today and forgot to hook up the wire (for
> sound) that goes from the back of the cd player to the sound card, but I
> still
> was able to hear music when I put a music CD in. So what is the purpose of
> this wire if I can still get sound without it being connected to the
> soundcard??
The computer is reading the data off the CD and processing it as
if it was a computer-generated audio signal. With the cable the
CD-ROM is able to play the CD directly - it has a built in DAC to
convert the signal to audio by itself. This second method is
preferable in most instances since less attention is needed from
the host computer - all that is needed is for it to send commands
when you start, stop or change tracks: once playing the computer
needs no further involvement. It also is not fooled by the 'copy
protection' sometimes added to CD's to make them more difficult
for a computer to read.
The primary disadvantage of this method is when using USB speakers
- in that instance the older analog system won't work since there
is no analog connection between the computer and the speakers.
> The primary disadvantage of this method is when using USB speakers
> - in that instance the older analog system won't work since there
> is no analog connection between the computer and the speakers.
>
> --
> Andrew Smallshaw
Thanks for all that information, so if I'm using USB Speakers on any
computer I should make sure to include this wire?
For example: I have a USB Audio Advantage Roadie from Turtle Beach which is
like an external sound card. This would need the wire
to work?
On Fri, 25 Jul 2008 09:51:41 -0500, "don" <don@panix.com>
wrote:
>> The primary disadvantage of this method is when using USB speakers
>> - in that instance the older analog system won't work since there
>> is no analog connection between the computer and the speakers.
>>
>> --
>> Andrew Smallshaw
>
>Thanks for all that information, so if I'm using USB Speakers on any
>computer I should make sure to include this wire?
>
>For example: I have a USB Audio Advantage Roadie from Turtle Beach which is
>like an external sound card. This would need the wire
>to work?
>
On 2008-07-25, don <don@panix.com> wrote:
>> The primary disadvantage of this method is when using USB speakers
>> - in that instance the older analog system won't work since there
>> is no analog connection between the computer and the speakers.
>
> Thanks for all that information, so if I'm using USB Speakers on any
> computer I should make sure to include this wire?
>
> For example: I have a USB Audio Advantage Roadie from Turtle Beach which is
> like an external sound card. This would need the wire
> to work?
No, you misunderstand me - this the instance where the analog output
_won't_ work. The CD ROM analog output bypasses the computer
altogether and is fed directly to the analog portion of your sound
card. In the case of true USB speakers (like yours, as opposed to
merely USB-powered speakers), the only connection between the
computer and the speakers is the digital USB connection - there is
no where for the analog signal to go.
CD player Sound Path ? 
Linear Mode
