THX quality issues

[marshahu_cr]

I have tried asking this question on a PC hardware forum but they have told me to go to the home theater forums because my question is to do with THX quality, and no one in the PC forums has any idea, even the manufacturers of the products!! It is a bit wordy but please bear with me:

I have a 7.1 Sound Blaster Audigy 4 PRO sound card which says it is THX certified. The PC has one DVD ROM drive for Region 2 discs and one for Region 1 discs as well as a copier which has been hacked to handle any region with unlimited changes, although the stability of this is questionable at times, so I only use this to copy discs. I currently have a set of Creative Inspire T7900 7.1 Speakers connected to the PC using 4x3.5mm jacks (analogue). My PC is connected to the TV which is facing the opposite way to the PC, so I intended to get a separate surround sound system to go around the TV, which will not only duplicate the 7.1 audio but also with the help of a standalone decoder, handle 2 analgoue inputs (TV, Mini System output via AUX out sockets), one coaxial digital input (digital audio from the PC when watching movies), and two optical digital inputs (Sky+ box and Xbox).

The Speakers I intend to buy are Creative Gigaworks S750 7.1 Speakers which do have a THX sticker on them, therefore complimenting my sound card and sounding excellent in THX movies and games.

http://uk.europe.creative.com/products/product.asp?category=4&subcategory=113&product=9306

I understand that real home theater enthusiasts will turn their nose up at these type of speakers because of their output when compared to proper THX speakers. The reason I chose these are because of my limited budget and also because 70W per channel is more than enough, and a meaty 210W sub will more than satisfy my needs in terms of bass. To be fair, the size of my living room is so small that proper THX speakers woudl be overkill and the cheapest THX amplifier will also have a huge amount of wasted inputs, power and features considering my needs.

The decoder I wanted to get is strictly a standalone decoder, with no amplification, it strictly acts as a decoder of various DVD formats and a source of inputs. This has a PC audio passthrough which allows 4x3.5mm analogue PC audio to passthrough to the speakers, in addition to the wealth of analogue and digital inputs. It is a Creative DDTS-100 Decoder.

http://uk.europe.creative.com/products/product.asp?category=4&subcategory=136&product=9468

My only query with this decoder is the fact that there is no THX label on the decoder. If I was to directly connect the THX speakers to the Sound Card I would get THX quality without any loss whatsoever. If I was to introduce a 3.5mm Socket doubler in the sound card outputs, so that two 7.1 speakers can co-exist and both take output from the sound card, would that have any effect on the quality of the THX audio? If I was to add the above decoder into the setup, would that reduce the quality of THX audio from the PC. I understand that I will not get THX quality audio from digital and analogue sources connected to the decoder, but will the passthrough function on the decoder affect the quality of the THX audio from the Sound card?

Thank you for your help, sorry about the wording

[Andrew Pratt]

THX is simply a post process algorthium that's applied over Dolby Digital, Dolby Pro Logic or DTS etc. THX also certifies products that meet its guidelines...but there's a host of levels for THX from Ultra and Select down to their PC products etc. The value of THX was hotly debated several years ago when the post processing actually did improve the sound and their testing standards were respectable. Today though you see THX stamps on a wide range of products and media and its post processing is largely ignored by most in the AV community.

THX rated speakers again have their following but its a very small crowd given that there are typically better sounding speakers for less money available without the THX badge. My suggestion would be to look into buying a real AV receiver and a set of smaller speakers to match. There's a host of companies selling Home Theatre's in a box that would likely be in about the same price point or lower then the Creative systems and would give you a more flexible upgrade path. I'll let some of the UK guys make some more specific suggestions on what's available locally but I strongly recomend you spend some time listening to all that's available and trust your ears.

[Gordon Moore]

Point to note also is that Creative bought the lion's share of THX from lucasfilm...hence why the THX "standards" now apply to pc speakers as well (eventually they plan to expand the certification program to include THX theater approved popcorn, recliners, bar fridges, remote controls, certain candy bars and pop drinks will follow......kidding on that part ).

I should point out that you can't expect a pc to be noise free (THX or otherwise) since there is a lot of RF interferance inside those boxes with fans, big unshielded powersupplies and the like. A pc just isn't built with sound quality in mind (read next to zero shielding)....

now if you were using it as simply a transport that's a horse of a different colour and has been done with much success (simply passing the bitstream along the wire to a receiver or pre/pro.

[purplepeople]

THX is not an indicator of good quality, just an indicator that a mfg was willing to put up with the nuisance of passing the standard. Case in point, most high-end studio monitors do not bother getting a THX certification. My favourite case in point are the excellent PMC monitors are which are used at Lucasfilm.

As for PC speakers, it is not well known that the Logitech satellites contain the Tangband drivers. I cannot vouch for the amplifiers, but I have had very good results with Tangband.

I also suggest replacing your 2 main left right speakers with a good used 70's receiver/amplifer and a pair of Tannoys (you are in the UK, n'est-ce pas?).

The problem with 7.1 is that there is no actual material which is 7.1 and barely any material that is 6.1 encoded. You are always better getting higher quality 5.1 than more lower quality channels.

ensen.

[marshahu_cr]

Thank you for your input - but I still dont have my question answered!

Gordon, I understand that PCs wont be totally noise free as opposed to home theater kits. I have done my best to make my PC noise free using silenicng kits and damping kits, the whole nine yards and now its merely a slight hum, which is not noticeable when the music is playing at a reasonable level. OK serisouly in terms of sound stakes every seems to think my sound card is perfectly capable of giving noise free output because of the specs (192khz 24bit audio in stereo, 106db SNR ratio, 96khz 24bit Audio in 5.1 or higher, 106db SNR ratio).

My sound card does actually have a 106db SNR ratio and barely any noise leaks from my current speakers even at maximum volume. The only noise is the hissing sound from the speakers amplifier and to check this I even unplugged them from the sound card with them on and the noise didnt change whatsoever. Even when tryin other amplifiers no noise was one and all the sources on the sound card were selected (with onboard solutions extra sources do add noise but this is not the case here)! Some onboard sound cards do have an annoying whine and fuzz all the time which are incredibly annoying but being a home theater buff and audiophile I steer clear of those solutions despite what the have to offer - rather little lol.

Whilst I am greatful for your input, I still do not udnerstand what you are sayin and my question remains unanswered - please elucidate and explain on this matter. Thanks so far!

[purplepeople]

I checked the online manuals and the specs for the DDTS-100 are quite vague, which leads me to believe that the sound quality is not as good as the marketing would suggest. Are you using the decoder for DTS soundtracks? Doesn't the Audigy already do all your decoding or are you just adding the remote control features?

As for specs, always cross-check. For instance, I doubt the power supply for the Gigaworks is capable of 700W output (7x70+210). Even if that were peak power, the picture of the satellite drivers would put their power rating at around 10-15W RMS max. In either case, that would be over a 3A draw for 220V outlets and that's assuming a digital amplifier.

Look, I'm not saying that these are bad buys, but I don't want you to be oversold by the advertising.

My suggestion still stand for getting a pair of small used Tannoys or Mordaunts with a 1970-era amp/receiver from Pioneer, Marantz or others. I think that will make your HT experience much better than just the Gigaworks. People are often surprised by how much better the really old units sound compared to "modern" equipment.

ensen.

[Gordon Moore]

Elucidate....there's a word you don't see everday (had to look that up just to be sure ops: ...since elucidate and explain appear to be pretty much the same)

Well I should have spelt out the RF part ( Radio frequency ) Interference for one. The generation of noise I'm talking about is electronic and magnetic not the physical audible notice you can measure with your ears. All the spinning fans with magnets and such generate little fields that distort the audio signal along the way which are then amplified along the way to your speakers. Most pc cabling is of the unshielded variety. All the interference will be picked up in the non-digital signal and the output will be hiss and hums and all other good stuff. In a pc this is hard to minimize.

One way that would help is an external soundcard that is free from the confines of your electronically noisy case.

One other thing....don't get too hung up on the specs of the creative card....printed specs should always be trusted with a grain of salt (and is what gave birth to 3rd party independent labs). THX is like Andrew said a re-equalization algorithm and a certification piece of paper that big companies pay lots of money for to have THX legitimacy stamped on their product to make you the consumer feel good about paying extra for the stamp. THX has it's place...in the controlled environment of the theater. THX stamped on home equipment loses some credibility because once out the door the environments are so varied that THX on one piece of gear (or cable for that matter) might not live up to expectations once introduced to uncontrollable factors (like other non-certified gear, equipment, or even rooms).

Okay so back to the questions and why the part answer....don't get hung up on the THX thing is the partial answer.

If I was to directly connect the THX speakers to the Sound Card I would get THX quality without any loss whatsoever

Probably not I suppose, but define "THX quality"? See my point, it's hard to answer since that's a subjective thing. THX quality is sometimes bested by objects that don't carry the THX badge of approval. So it's hard to answer that one but from your POV (point of view) ...the answer would most likely be "no" .

If I was to introduce a 3.5mm Socket doubler in the sound card outputs, so that two 7.1 speakers can co-exist and both take output from the sound card, would that have any effect on the quality of the THX audio?

similar question, similar answer....also you are splitting the non-amplified signal (I assume and from the sounds of things you are splitting all 4 outputs?)...it might work so long as you aren't running both sets of speakers at the same time. Anytime you introduce things like splitters you are affecting the sound quality....so the answer in your defined terms is "Yes" you will "affect" the sound quality. The caveat being, for the speakers you are buying....your ears will most likely not "hear" the difference.

If I was to add the above decoder into the setup, would that reduce the quality of THX audio from the PC.

As you perceive "THX Quality" then the answer is most definitely "Yes".

The real world answer as your ears define the audible difference is "most likely No".

but will the passthrough function on the decoder affect the quality of the THX audio from the Sound card?

Mostly answered in my opening response but, as you perceive THX from a certified device, then the answer is "Yes".

The reality is most likely "No measureable difference as far as THX is concerned however... a different decoder will usually yields a different sound and hence it will either appeal to you more or less than the decoder in your pc".

[Andrew Pratt]

As I said above my advice would be to buy a HTiB and just run a digital connection from your soundcard to the receiver and let it do the decoding and amplifying the signal to your speakers. Sending a single digital connection is easier then sending 6 analog cables which is what you'd have to do if you used the Aud card to decoded 5.1.

[marshahu_cr]

Gordon, thank you for your input, it is a lot clearer now and I understand how valuble THX rating really is.

Andrew, the reason I need analogue outputs form the PC as well as digital is becausing my PC is used to play DVD audio discs. If I get a HTIB I'll need to increase the budget to get one which includes DVD audio discs. Also some games I play are better through the Analogue output - I use digital to take advantage of the 24/96 sound quality - one of the features of this decoder is DTS 24/96 sound.

Also I know that DVD movies have not gone beyond 6.1 sound standards but in EAX 4 Games which use positional audio, the more speakers, the better! :W More unfair advantage

Nevertheless thank you for your input it is a lot clearer now!