lokokkee

For a typical home theatre setup (i.e. nothing fanciful, just consumer grade amp, speakers etc.), which is the better audio track to use, Dolby Digital 5.1 or DTS? I read somewhere that DTS has a lower compression rate, hence retains more details, but can't hear that much difference between the two in a A/B test.
Another question is, which is the better connection to use for the digital audio output, coaxial or optical (again, nothing expensive, just off the shelf cables)?
Thanks.

paulr

5.1 or dts.As far as i know not all films are recorded in dts so you dont always have the option.dts is supposed to be better,cant really notice a huge difference myself.

stevebt

iTrader: (8)

i would go for an optical digital cable and if a dvd has been made in DTS i would listen to it in DTS but turn the sound down as its much louder in DTS

dba

I can tell,but only just

TopBanana

optical or coax - it makes no difference

DTS sounds better, if you can't hear the difference then don't worry about choosing the 'right' format. Either your kit isn't good enough for it to make any difference, or you're losing your hearing

lokokkee

I have a Yamaha amp with Boston Acoustics front, Infinity center, JVC rear speakers, a Yamaha subwoofer and JVC DVD player. I know they are not quite matched (collected when the individual components were each on sale), but on specs, they are above mid-range units in terms of frequency response and power output. I find that DTS is softer, not louder, than Dolby 5.1 at the same settings, and if as they say one's hearing sensitivity decreases with age, I may have reached the stage where they all sound the same (I once held the position as the oldest member on SN until PS Lewis came along and claimed the title, lol), or may need to tone down the subwoofer a bit the next time.

hades

Relative volume levels between DTS and DD 5.1 will vary according to your kit, the recording etc. In theory, they should all be the same, but in practice it will rarely turn out like that. Simlarly, some DVDs / CDs etc will sound louder than others.

A lot of kit can apply compression to try and "smooth out" the volume levels - i.e. amp up the quiet signals more than the loud - at the expense of some dynamic range. If you're in a terraced house, it means you can turn it up enough to hear quiet dialogue without upsetting the neighbours during the loud bits. If you're in a detached house and your kit can handle it, turn the compression off - makes things a lot more dramatic!

As for DTS versus Dolby, having tried a couple of music DVDs that have both, there is no question IMHO that DTS is very noticeably better, although on smaller set-ups, you might not notice the difference so much. Similarly, there is a smaller but definite difference between co-axial and optical digital links. Anyone with a high end set-up would confirm both of these, IMHO.

paulr

How important is it to correctly "set up" your home cinema system?
I just plugged mine in and away i went.
No setting speaker distances and all the other stuff.

Sony dvd player/Denon 2802/Energy take 5.

lokokkee

Hades, I have turned the compression on the DVD player off, so it should be playing at maximum range. I live in a detached house and usually with curtains drawn and aircon on, can play at a volume level loud enough to vibrate the sliding glass door (about 1/3 of 100 watts rms/channel). I have a CD player connected via the optical cable (it was purchased first, so got the better connection) and the DVD via the coaxial. Too lazy to get behind the TV console to change the cabling if this won't make too drastic a difference. I am more into movies, so DVD player is my priority.
A proper setup of the amp is important because the rear channels carry delayed signals that should be matched to the speakers placement, otherwise your helicopter may sound nearer or farther than it actually is flying in from behind.
Another question: my Yamaha amp has a DSP setting for theatre sound. As a purist, should I use this instead of Dolby 5.1 or DTS, since this is supposed to simulate a theatre, vs. a sitting room setting?

lokokkee

Another question: I am using an RCA type interconnect cable as a digital coaxial. Is there any physical difference (other than sound quality) between an interconnect and a coaxial?

dba

I cant hear any difference between the two,but i have 2 chairs and a sette in the way,like most people i think

corradoboy

DTS is significantly better than DD on my system on many (but not all) discs. It has a much more detailed and open sound and much better surround separation.

I favour coaxial digital interconnects. The disc is read by laser and the resulting digital datastream is output from the op-amps as an electrical signal. If you use coax, it is this signal which is directly relayed to your AV amp. To use optical, the delicate digital datastream has to be converted to light pulses which then travel down the fibreoptic cable to a light receiver, only to be converted back into an electrical signal. Why add all these stages where corruption can occur? Some people wrongly believe that it is the light from the laser pick-up which travels down the optical cable. It isn't! So it's un-necessary. IMHO.

TopBanana

DD and DTS are sent down the wire in checksummed packets - so if there's any corruption you get a brief drop-out of sound.

corradoboy

There's more chance of corruption with optical.

Geddon

I always use DTS if available. It does seem to be louder than DD but more consistent. Ie watching a film late at night on DD, you have to have reasonable volume to hear the speech but then turn down for really loud effects- annoying. Don't have to touch with DTS. Also sounds better IMHO.
Coax is supposed to be better although I'm not sure I've ever noticed.

bigsinky

can't tell the difference between DD5.1 and DTS? get the R1 version of The Bone Collector and skip to the Amtrak train scene. the DTS version sounds as if the train has stopped in my front room.

DTS tracks tend to be alot more dynamic and even better if you have an amp that can do DTS ES with a rear centre. time to upgrade my sony amp me thinks.

cheers

big sinky

AndyC_772

iTrader: (2)

The reason coax is theoretically 'better' is nothing to do with data corruption, it's to do with jitter and clock recovery.

The problem stems from the fact that the master clock source for the whole system is physically located in the DVD player; data is read out from the disc, decoded and sent up the cable (coax or optical) at a rate which is determined by the DVD player.

The AV amp then has to try to recover this clock, so it knows when to sample the data from the DVD player and so that it can send samples to its DAC at precisely defined intervals. It does this by detecting the precise instant at which the input swaps between 1 and 0, and synchronising its own clock to these transitions.

With a coax cable, the signal that comes in is nice and strong with sharply defined transitions, so the recovered clock can be accurte and stable. With optical transmission, though, the signal at the output of the optical receiver is much weaker. Although this doesn't cause errors, it does make the exact instant at which the transition between 0 and 1 occurs harder to determine. This variation in transition time is called 'jitter', and it means that the AV amp's clock also becomes less stable.

Jitter in the AV amp's clock means that data is sent to the DAC at irregular intervals, which affects sound quality.

dsmith

Here we go again...

Funny how given the choice in Data Comms I'd take an optical interconnect any day of the week.

Deano

TopBanana

Andy - jitter isn't an issue for DTS or DD. The sound is packetized and buffered - the master clock is in the AV processor / amp. PCM is a different matter (a raw stream from a CD player, for example).

AndyC_772

iTrader: (2)

Understood - but there still has to be some synchronisation to ensure that long-term slight differences in clock speed don't cause a mismatch between the data rate required by the DAC and that provided by the DVD player. Unless, of course, there's some mechanism for coping with the occasional dropped or repeated packet; this is standard practise in telecommunications but I'd be surprised if it were done in a hi-fi environment.

TopBanana

As I understand it, the Dolby Digital decoder will resample the sounds stream in order stretch or compress it slightlty to account for drift. Clearly if they're way out ( >1%? ), you'll get drop outs.

JonDBM

When I had my amp demo'd, I had Gladiator played both in DD and DTS. No question, DTS is a brighter and louder sound. The "chings" when the swords hit were a much crisper sound with DTS.

From an electronic point of view, digital coax is def better than optical, as to go from electrical - optical - electrical domains introduces more noise than a pure digital electrical coaxial cable if you have a good quality cable.

However, most region 2 dvds only have DD soundtrack - so you must have an amp that supports both - which pretty much they all do these days anyway.

Jon.

lokokkee

Thanks for the technical enlightenment. I thought Scoobynetters are mostly IT techies, but looks like there's quite a lot of sound/electrical engineers aboard too. Lucky I am not into high end hi-fi, otherwise I will be spending a fortune to achieve the last 1 or 2 % of perfect sound reproduction. At least now I don't have to mess around with the interconnects to switch the optical and coaxial cables around the various sources. I suppose the next format battle will be between DD EX and DTS ES, with THX thrown in to make it more interesting. It pays to have neighbours who are into karaoke, so can't complain too much about my home theatre.

dr_ming

AndyC_772 is completely correct regarding the difference between optical and coax for consumer hi-fi. And, unlike a lot of the BS talked about hi-fi and sound 'quality', the clock jitter caused by optical interconnects is a measurable phenomenon. Since clock jitter = innacurate sample timing = high frequency harmonic distortion, it must be a bad thing Should be noted hawever, that the coax cable does have to be a proper piece of 75 ohm cable, correctly terminated (with 75 ohms!), at either end.

Dr Hu

Look here:-

http://www.avforums.com

go to cables & cabling and read the sticky thread from 'The Beekeeper' about cables, 75ohm connectors and such - interesting reading.....

dr_ming

Very interesting thread (which pretty much re-iterates what I said above about the criticality of teh coax cable having 75 ohms characteristic impedance and being properly terminated). Bit long though

For once something written about cables that is vaguely factual, based of scientific/engineering principles and pretty much BS free. Pity he had to use TAG as a source of reference though .