- Joined
- Apr 1, 2002
Introduction:
The most important thing to remember is that speakers are analog. That's just the way it is. So at some point your digital connection will have to be converted into analog using DACs.
The 2nd thing is that the DACs tend to have the biggest influence on the quality of the sound.
The 3rd thing to remember is a few key acronyms:
APU = Audio Processing Unit (named by the same folks who named the GPU, nVidia)
DAC = Digital to Analog Converter
DD = Dolby Digital
AC3 = Audio Coding version 3 - lossy encoded audio format developed by Dolby
DTS = Lossy encoded audio format developed by Digital Theater Systems
PCM = Pulse Code Modulation (an uncompressed digital sound signal)
S/PDIF = Sony/Philips Digital Interface (standard digital audio interface using RCA jacks and 75ohm coax cable)
TosLink = Toshiba Link (standard digital audio interface using fiber optic cable)
The 4th thing to keep in mind is that digital sound comes in many different formats. There are three main digital sound formats (each with sub-formats) that we need to worry about. PCM is an uncompressed stereo format. Dolby Digital (AC3) and DTS are competing multichannel formats. DACs will convert PCM, but DD and DTS need to be decoded first.
--------
So, first a bit of history:
In a typical analog computer setup, your sound follows the following path (simplified, but you get the idea): APU -> DAC -> Mini-Amplifier -> Analog audio cable -> Amplifier -> Speaker
The APU generates and processes the audio on your computer - different APUs are capable of doing different things (DTS decoding, real time effects, etc). Audio is typically output from the APU in PCM format, usually at 16bit, 44.1khz (CD quality).
This PCM bit-stream is then fed to the DAC where it is converted into analog sound.
From the DAC the sound is passed to a small amplifier which boosts the output level so you can use headphones or small unpowered speakers. Often these small amps are included in the same chips as the DACs.
The sound then travels down the analog audio cable to the amplifier. This amplifier can either be a standalone unit (ie: a receiver) or built into the speaker (ie: typical computer speakers). Different amplifiers offer different controls, but most offer at least volume and some kind of tone adjustment.
From the amplifier the sound is passed to the speaker.
This is how it stayed for a long time. People slowly started adding channels, but all you had to do is add more DACs, amps, and speakers. Generally people were happy.
But then came CDs together with consumer level Dolby Digital and DTS, and the sound card people thought "Hey, we can make a lot of money off of this!".
Creative Labs was pretty much the first company off the block with their digital speakers. They would pass the stereo PCM signals from the APU down a proprietary digital DIN connection to the speakers. The speakers would contain the DACs and amps, as well as the speakers themselves. Because the DACs in the speakers weren't really any better then the DACs on their soundcards (you had to use their cards because of the proprietary speaker connections) there wasn't really much difference in sound quality. But the marketing people got to put the words "digital" on the boxes.
The other thing that appeared around this period was the S/PDIF and/or TosLink connectors. Most cards would allow two things with these connectors - output the front speaker's stereo PCM signal and allow "S/PDIF passthrough". S/PDIF passthrough just passes a digital bit-stream from the source (ie: computer DVD drive) directly to the S/PDIF and/or Toslink connector without the APU (or anything else) doing anything to the signal. Most of the cheaper sound solutions to this day still only do these two things with the digital out connectors.
For a while companies (mainly Creative Labs) continued to muck around with their proprietary digital speaker connections. Creative Labs was eager to keep this arrangement because they had a monopoly on sound cards. If you wanted a soundcard you pretty much had to get a SoundBlaster. If you wanted digital speakers for your SoundBlaster you had to talk to Creative Labs.
Then came some real digital speaker packages that would not only decode stereo PCM, but also AC3 and DTS. Companies like Logitech started producing great setups like the Z-680s and people flocked out to buy them in droves. They eagerly plugged them into their waiting S/PDIF and TosLink ports and then started screaming and swearing when they only got stereo sound out of them. When playing movies they could activate S/PDIF passthrough and use the decoders and DACs in their digital speaker packages, but when playing games they had to use the soundcard DACs and analog cables to get multi-channel sound.
And then nVidia brought out nF1 with Soundstorm. This introduced Dolby Digital Live! realtime encoding and allowed the APU to pass a multi-channel AC3 bit-stream to the speakers instead of being limited to a stereo PCM bit-stream. Suddenly people noticed that their digital speaker packages worked like they were supposed to. Although nVidia backed out of the DDLive! encoding after the nF2, other companies like C-Media, and Realtek started picking it up.
Not to be left out, DTS recently started offering their version of DDLive!, called DTS Connect. DTS Connect does exactly the same thing as DDLive!, except it encodes the audio into a multichannel DTS bitstream instead of a Dolby Digital AC3 bitstream.
So which is better? DTS tends to have higher bitrates (less lossy compression) and is generaly regarded to be higher quality. We'll have to wait for some reviews of DTS Connect computer audio chips to be sure 'tho.
DDlive! homepage
DTS Connect homepage
--------
Ready to take the plunge?
So that's where we are today. Stuck in a big mess. Ideally we want a setup that looks like: APU -> DDLive!/DTS encoder -> Digital cable -> AC3/DTS Decoder -> DAC -> Amplifier -> Speaker
For some reason people like to start at the speaker end, so that's where I'll start. There are two routes you can take. You can get a digital computer speaker package (like the Logitech Z-5500) or you can go for a home theater receiver (like the Yamaha HTR-5840). Both have pros and cons. The computer packages tend to be smaller and cheaper. The receivers offer better sound and better connectivity. Either way you'll want to make sure that the setup you choose has the connections you need, as well as supporting both Dolby Digital and DTS decoding (all digital receivers should support PCM).
When you're looking at self powered speakers and receivers remember that there are many ways to measure power. One 120W amp may only provide half the output as another 120W amp. http://www.bcae1.com/voltages.htm
Next up is the digital interface. There are many threads full of people swearing that TosLink is clearer, or S/PDIF is crisper but when it comes down to it remember it's all 1s and 0s, and as long as they get to the other end of the cable it'll all sound the same. S/PDIF tends to be cheaper and more flexible then TosLink. You can use the composite video cable that probably came with your last video card purchase and save some $$$. Toslink is better for long distance runs (ie: more then 5m (15').
Some older S/PDIF equipment is not correctly grounded and you may get a ground loop problem. This will result in your audio popping/crackling/popping or cutting out, no sound at all, or a hum. If you get any of these symptoms try a TosLink cable. Because a TosLink cable is not electrically conductive ground loops will be eliminated.
The final thing you'll need is the soundcard - unless you get something with DDLive! and/or DTS Connect encoding you'll get stuck with the old stereo PCM sound for everything except DVD movies. See a few posts down for a list of DDLive! and DTS Connect soundcard & motherboards.
Once you get your soundcard installed just enable DDLive! encoding, turn on S/PDIF passthrough in everything you can find, and you're good to go.
The most important thing to remember is that speakers are analog. That's just the way it is. So at some point your digital connection will have to be converted into analog using DACs.
The 2nd thing is that the DACs tend to have the biggest influence on the quality of the sound.
The 3rd thing to remember is a few key acronyms:
APU = Audio Processing Unit (named by the same folks who named the GPU, nVidia)
DAC = Digital to Analog Converter
DD = Dolby Digital
AC3 = Audio Coding version 3 - lossy encoded audio format developed by Dolby
DTS = Lossy encoded audio format developed by Digital Theater Systems
PCM = Pulse Code Modulation (an uncompressed digital sound signal)
S/PDIF = Sony/Philips Digital Interface (standard digital audio interface using RCA jacks and 75ohm coax cable)
TosLink = Toshiba Link (standard digital audio interface using fiber optic cable)
The 4th thing to keep in mind is that digital sound comes in many different formats. There are three main digital sound formats (each with sub-formats) that we need to worry about. PCM is an uncompressed stereo format. Dolby Digital (AC3) and DTS are competing multichannel formats. DACs will convert PCM, but DD and DTS need to be decoded first.
--------
So, first a bit of history:
In a typical analog computer setup, your sound follows the following path (simplified, but you get the idea): APU -> DAC -> Mini-Amplifier -> Analog audio cable -> Amplifier -> Speaker
The APU generates and processes the audio on your computer - different APUs are capable of doing different things (DTS decoding, real time effects, etc). Audio is typically output from the APU in PCM format, usually at 16bit, 44.1khz (CD quality).
This PCM bit-stream is then fed to the DAC where it is converted into analog sound.
From the DAC the sound is passed to a small amplifier which boosts the output level so you can use headphones or small unpowered speakers. Often these small amps are included in the same chips as the DACs.
The sound then travels down the analog audio cable to the amplifier. This amplifier can either be a standalone unit (ie: a receiver) or built into the speaker (ie: typical computer speakers). Different amplifiers offer different controls, but most offer at least volume and some kind of tone adjustment.
From the amplifier the sound is passed to the speaker.
This is how it stayed for a long time. People slowly started adding channels, but all you had to do is add more DACs, amps, and speakers. Generally people were happy.
But then came CDs together with consumer level Dolby Digital and DTS, and the sound card people thought "Hey, we can make a lot of money off of this!".
Creative Labs was pretty much the first company off the block with their digital speakers. They would pass the stereo PCM signals from the APU down a proprietary digital DIN connection to the speakers. The speakers would contain the DACs and amps, as well as the speakers themselves. Because the DACs in the speakers weren't really any better then the DACs on their soundcards (you had to use their cards because of the proprietary speaker connections) there wasn't really much difference in sound quality. But the marketing people got to put the words "digital" on the boxes.
The other thing that appeared around this period was the S/PDIF and/or TosLink connectors. Most cards would allow two things with these connectors - output the front speaker's stereo PCM signal and allow "S/PDIF passthrough". S/PDIF passthrough just passes a digital bit-stream from the source (ie: computer DVD drive) directly to the S/PDIF and/or Toslink connector without the APU (or anything else) doing anything to the signal. Most of the cheaper sound solutions to this day still only do these two things with the digital out connectors.
For a while companies (mainly Creative Labs) continued to muck around with their proprietary digital speaker connections. Creative Labs was eager to keep this arrangement because they had a monopoly on sound cards. If you wanted a soundcard you pretty much had to get a SoundBlaster. If you wanted digital speakers for your SoundBlaster you had to talk to Creative Labs.
Then came some real digital speaker packages that would not only decode stereo PCM, but also AC3 and DTS. Companies like Logitech started producing great setups like the Z-680s and people flocked out to buy them in droves. They eagerly plugged them into their waiting S/PDIF and TosLink ports and then started screaming and swearing when they only got stereo sound out of them. When playing movies they could activate S/PDIF passthrough and use the decoders and DACs in their digital speaker packages, but when playing games they had to use the soundcard DACs and analog cables to get multi-channel sound.
And then nVidia brought out nF1 with Soundstorm. This introduced Dolby Digital Live! realtime encoding and allowed the APU to pass a multi-channel AC3 bit-stream to the speakers instead of being limited to a stereo PCM bit-stream. Suddenly people noticed that their digital speaker packages worked like they were supposed to. Although nVidia backed out of the DDLive! encoding after the nF2, other companies like C-Media, and Realtek started picking it up.
Not to be left out, DTS recently started offering their version of DDLive!, called DTS Connect. DTS Connect does exactly the same thing as DDLive!, except it encodes the audio into a multichannel DTS bitstream instead of a Dolby Digital AC3 bitstream.
So which is better? DTS tends to have higher bitrates (less lossy compression) and is generaly regarded to be higher quality. We'll have to wait for some reviews of DTS Connect computer audio chips to be sure 'tho.
DDlive! homepage
DTS Connect homepage
--------
Ready to take the plunge?
So that's where we are today. Stuck in a big mess. Ideally we want a setup that looks like: APU -> DDLive!/DTS encoder -> Digital cable -> AC3/DTS Decoder -> DAC -> Amplifier -> Speaker
For some reason people like to start at the speaker end, so that's where I'll start. There are two routes you can take. You can get a digital computer speaker package (like the Logitech Z-5500) or you can go for a home theater receiver (like the Yamaha HTR-5840). Both have pros and cons. The computer packages tend to be smaller and cheaper. The receivers offer better sound and better connectivity. Either way you'll want to make sure that the setup you choose has the connections you need, as well as supporting both Dolby Digital and DTS decoding (all digital receivers should support PCM).
When you're looking at self powered speakers and receivers remember that there are many ways to measure power. One 120W amp may only provide half the output as another 120W amp. http://www.bcae1.com/voltages.htm
Next up is the digital interface. There are many threads full of people swearing that TosLink is clearer, or S/PDIF is crisper but when it comes down to it remember it's all 1s and 0s, and as long as they get to the other end of the cable it'll all sound the same. S/PDIF tends to be cheaper and more flexible then TosLink. You can use the composite video cable that probably came with your last video card purchase and save some $$$. Toslink is better for long distance runs (ie: more then 5m (15').
Some older S/PDIF equipment is not correctly grounded and you may get a ground loop problem. This will result in your audio popping/crackling/popping or cutting out, no sound at all, or a hum. If you get any of these symptoms try a TosLink cable. Because a TosLink cable is not electrically conductive ground loops will be eliminated.
The final thing you'll need is the soundcard - unless you get something with DDLive! and/or DTS Connect encoding you'll get stuck with the old stereo PCM sound for everything except DVD movies. See a few posts down for a list of DDLive! and DTS Connect soundcard & motherboards.
Once you get your soundcard installed just enable DDLive! encoding, turn on S/PDIF passthrough in everything you can find, and you're good to go.
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