Dolby Digital and THX
Ralph Willgoss
Simply what is the difference between these two?
Do they need different amps? I thought i knew the difference but i am confused
again.
thanx in advance
Ralph
Bruce Probst
On 1 May 97 03:58:58 GMT, rw...@uow.edu.au (Ralph Willgoss) wrote thusly
about "Dolby Digital and THX":
>>Simply what is the difference between these two?
>>Do they need different amps? I thought i knew the difference but i am confused
>>again.
There are no similarities. They are completely different things.
THX is an independent reference standard. Equipment that is "THX ready"
is built to a particular level of quality and meets the requirements for
a home theatre system as defined by THX. Check out http://www.thx.com
if you want more info on what those standards are.
Dolby Digital (also known as AC-3) is an audio format. It provides for
separate audio channels for front L&R, centre, rear L&R and subwoofer.
(This is different from Dolby Pro-Logic where the rear speakers are a
single mono channel and there is no separate subwoofer channel.) At
present there are only two ways of getting DD sound in home theatre:
laser disc or DVD. In any case you need a DD decoder, either as a
separate pre-amp or built in to your receiver. (Some of the new DVD
players have a DD decoder built-in.) (For laser disc players, you also
need a DD RF output. Most new LD players have this already, and it's
possible to add one to older units via a relatively inexpensive
upgrade.) DD is backwards-compatible with DPL, so if you don't have a
DD decoder you can still listen to a DD-encoded laser disc on a normal
DPL unit - you just don't get the extra sonic effects.
Similar to DD is DTS. That is, it's similar in that it provides
separate channels etc. However, it is not compatible with DPL or DD;
you must have a DTS decoder to be able to listen to it. Currently DTS
software is limited to a handful of laser discs and compact discs. (It
will probably also become available on DVD at a future date.)
DTS is generally regarded as a "better" format than DD, because it uses
much less data compression in the digital signals. However, DD is more
widely available and is rapidly becoming a HT standard. DTS will
probably remain as an optional high-end feature.
--
Bruce Probst bpr...@melbpc.org.au
MelbPC User Group CIS: 71154,3171
Melbourne, Australia MSTie #72759
I am not an animal! I am... well, not an animal.
John Richardson
Ralph Willgoss <rw...@uow.edu.au> wrote in article
<rw03.862459138@wumpus>...
>
>
> Simply what is the difference between these two?
> Do they need different amps? I thought i knew the difference but i am
confused
> again.
>
>
> Ralph
>
As someone has already pointed out these are two separate things. The main
point to consider I believe is that the newer formats (such as AC3) are
encoded onto DVD's in the same format that was intended to be played back
in a large cinema with hugely different accoustical qualities when compared
to the home. THX is about equipment standards which when met can hopefully
produce better (more cinema like) results in the home environment. The THX
processor for example modifies the sound after the AC3 signal has been
decoded, the sound is modifyed in several ways to overcome differences in
room size and dynamics between a large cinema and the home. For example, in
a cinema you may be 40, 50 or 60 feet from the speakers, the boost in high
frequencies required for this to sound natural in the cinema can be
overpowering (especially at high volume levels) in the home where you sit
perhaps 10 to 15 feet away - THX attempts to overcome this and other
differences.
With the advent of DVD and more dynamic multi channel sound reproduction,
THX or at least some sort of signal massaging becomes more important.
Hope this helps,
JR