Re: Digital Speakers
Bijan Soleymani wrote:
> Rich Puhek <rpuhek@etnsystems.com> writes:
>
>
>> Your speakers are not digital. They may be hyped in the literature
>> as "digital ready" (right next to the part where they sell you
>> insanely overpriced "digital speaker wires"), but a speaker is an
>> analog device. [1]
>
>
> Some speakers are indeed "digital". The speaker does function in an
> analog way (that's the only way a speaker can work). But the
> connection between the computer and the speaker is digital. The
> speaker itself contains a digital to analog (D/A) converter and
> converts to analog itself. This would move the D/A converter out of
> the computer case where there is noise and whatnot. Of course a
> professional solution would use a D/A converter seperate from the
> speakers.
>
> The original poster may or may not have such speakers, but they do
> exist.
>
> Bijan
>
Possibly, but then it's not a "speaker", it would be an all-in-one
speaker and amplifier. I would be very surprised if the exact setup was
digital between the computer and the speaker. Every truly digital setup
I'm familiar with uses a coax or fiber connection to handle the digital
signal (usually between high end laserdisc or DVD players and high end
amplifiers).
One caveat on that, it would also be possible to have the "speaker"
include circuitry for a dolby decoder to extract the relevant portion of
the signal. In that case, it's still not truly "digital" in that the
speaker's amplifier and related active circuitry is decoding the Dolby
signal.
A truly digital audio stream is most probably Dolby 5.1 Dolby Digital
sound, which would be encoded on a DVD or digital cable signal, needs to
be broken into components (left, center, right, left-surround,
right-surround, and LFE) by a decoder before it even hits a D/A (or a
preamp, which is actually what will be most noise-sensitive).
In an application with a speaker output, you're sending analog data out
through a speaker port. I'd suspect that a "digital" speaker system
(like common home-theater systems with surround sound) are actually
processing the Dolby Surround Sound signal or Dolby Pro Logic signal.
Both of which, unless I've confused myself on a Friday afternoon, are
analog techniques of encoding extra channels in a stereo signal. This
uses just two analog channels, but some nifty phase-shifting tricks
encode the "extra" channels. Dolby's website has a very good explanation
of the technical aspects of both encoding methods. The explanation
doesn't include gory details like the transfer functions of the encoding
process, though.
Check closely on the specs for the "digital" speakers, and I'm sure
you'll find that either:
1) They are a speaker _system_, with a 5.1, 7.1, or similar
decoder/amplifier (with a digital input)
2) They're a hyped "digital ready" speaker, which is just a regular
speaker in a sexy case, with a digital-ready Crutchfield price.
--Rich
_________________________________________________________
Rich Puhek
ETN Systems Inc.
2125 1st Ave East
Hibbing MN 55746
tel: 218.262.1130
email: rpuhek@etnsystems.com
_________________________________________________________
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