- Aug 6, 2001
- 31,204
- 45
- 91
1. Intro
2. Disadvantages of digital
3. Advantages of digital
4. Soundcards
5. Digital Speaker Systems
6. Help, it's only playing on 2 speakers
7. Cables / Connections
8. Bit-Perfect Info
1. Intro
Ok, so someone has linked you to this thread to give you some info on digital audio. Just some stuff I wanted to cover before I get into specifics...
Speakers are analog. Sound information starts off in your computer as digital and at some point needs to be converted to analog before it comes out your speakers. Even "digital speakers" are analog.
DD (Dolby Digital) and DTS (from Digital Theater Systems) are both multichannel digital sound sound formats that allow multichannel audio to be compressed into a digital stream.
So as I stated above, what comes out our speakers / headphones is analog in the end, so most of the digital issues and "features" that come up are mostly related to just when this conversion happens. When people get really serious about audio, they will more often than not try to keep it analog all the way from start to finish by starting from an analog source like records (anyone remember those?
) and keeping it analog all the way along their chain of components before it ends up coming out their speakers.
In the world of computers, we're all starting with digital as our source, so the options we have are mostly limited to when and how the conversion to analog is going to happen.
2. Disadvantages to Digital
Ok, so basically there are two kinds of a digital signal that a soundcard can put out. One would be PCM, which is just stereo, and the other is a compressed multichannel stream (DD or DTS).
If you want to use digital, most cards out there with a digital output will only be able to give you PCM output and pass along a previously encoded DD/DTS stream. That means that you would get the desired output from stereo sources (like music) with PCM and you'd get the desired output from pre-encoded sources (like DVD movies) with DD/DTS passthrough.
The major limitation here is when it comes to games. In the case of games, individual sound track information is not available for each channel since the sound is dynamic. Since it's not all pre-recorded, in order to output a DD/DTS stream with the proper 5.1 info, your soundcard would have to encode the surround info into a DD/DTS stream in real time.
There are cards out there than can do this now, and it is becoming more widespread. A major note here is that Creative's cards do not support DD/DTS encoding. With creative's monopoly on EAX higher than 2.0, if you do get a card that encodes multichannel digital streams, you will not get all the EAX effects that the latest Creative cards are capable of.
Ok, now that I've covered that...
Even if you do get a card that outputs digital as you desire, that's probably not going to be any better quality than a decent analog card could output... and will actually probably get you lower quality results. As you know, sound has to end up analog... so by outputting digital, all you are doing is postponing when this conversion happens. In the majority of cases I have read, people want to hook up digitally to a set of computer speakers (like Logitech z-5500s, etc.). The issue is that the control pod on the speakers is now doing the work that the soundcard would have done initially if it had been outputting analog. If you get a decent soundcard, it will probably do as good or a better job at this than the control pods on these speaker sets will do.
Also, by its very nature, DD/DTS streams are compressed audio. You're potentially giving up some quality be using these sound formats. Also, there may be slight delay in this encoding process so may experience some delay in your final sound.
3. Advantages to Digital
If you have some high quality sound components in your system, they may do a better job with a digital signal and processing it vs. what your soundcard could do in it's analog output.
If you have some high quality sound components that process digital signals and apply some calibration / equalization effects to those inputs, this may be a preferred way to connect as 5.1 analog connections tend to not have any processing done on them.
Connecting one digital cable can be more convenient than several analog cables.
If you are experiencing some ground loop problems between your computer and sound system, a digital optical connection would eliminate that issue.
If you want to connect to a receiver that lacks 5.1 analog input, digital is your only option for getting surround sound.
There is the potential for less signal interference in the transmission of a digital signal to your sound system than if you were transmitting analog.
4. Soundcards
Ok, now that I've kind of gone over some basics... what's good?
If you just want to output stereo PCM and have passthrough of DD, the Chaintech AV-710 is a great budget card. In addition to the ability to get bit-perfect digital output, the Chaintech card also has one good quality analog output on it. This would be a good card to get if you want to connect a set of 2.0/2.1 speakers for music listening or if you want those basic digital sound output options.
If you think that you want a card that encodes digital streams, you have some options. Once upon a time your only option was soundstorm audio integrated into some older motherboards, but rather recently a couple companies have started producing DDL / DTS live cards. The Turtlebeach Montego and Bluegears / HDA X-Mystique were some of the first cards out with that feature.
More recently some integrated audio solutions have started to have this feature and Auzentech has stated to come out with new products that include this feature. The X-Plosion was introduced after the X-Mystique and has added the ability to enocde DTS in real time in addition to DD. The DDL connection is compressed to 640Kbps, so DTS at 1.5Mbps should produce a better final result than the DD output. Their X-Meridian is their newest card that is in the works and concentrates more on analog output quality.
For the majority of comptuer users who use analog speakers and want good gaming performance, Creative is pretty much your main option. With deals on X-Fi in the ~$70 range, that's a solid choice on a card for most users. Especially for someone that wants to game on headphones, the X-Fi has a lot to offer. The reason to get X-Fi is for it's high quality analog audio output, it's surround headphone feature, and it's multichannel gaming abilities. By connecting to it digitally, you're really not taking advantage of most of what makes the X-Fi a good card. On a tighter budget, the older Audigy 2 cards also offer good bang for your buck for a gaming card.
One issue many people have with the digital connectivity on Creative sound cards is the upsampling algorithm it employs. The card at times takes audio and upsamples it to 48KHz and outputs that out the digital connection. Most music is 44.1KHz and upsampling is a process often looked down upon in the audio world. After years of not having an option to disable upsampling on their Audigy series of cards, X-Fi cards can be set to output bit-perfect at 44.1kHz without upsampling. This is possible in Audio Creation Mode.
There are plenty of other cards out there, most notably ones that have good analog outputs for music quality and more professional cards that have a lot mor connectivity options for inputs/outputs.
That's kind of beyond what this thread is about so go nuts on the research in your own
Just as a rule of thumb, a good starting point balancing your audio budget might be to spend twice as much (or more ) on speakers as your soundcard. If you're thinking headphones, you can get better quality for cheaper, so as long as you have a pretty good pair, X-Fi may be a good way to go if you're a gamer.
Cheesehead adds:
"IMHO, a good USB DAC (PCM2706 for USB-> I2S, and TDA1543s or the like for the DAC) is the best way to go. Cheap, too-TDA1543 DAC kits can be had for a whopping 40$ on eBay, and a USB->I2S adapter can be made for 10$.
As an added bonus, an outboard PSU is easy. Just run the TDA1543 and output stage off of a wall-wart with some big power filtering caps on it."
5. Digital Speaker Systems
Ok, so if you have a digital speaker system, is it better to use a digital connection?
As I've gone over above, in most cases probably not if you can just get a card with good analog output instead. A case where it might be a good idea is if you have integrated audio with pretty bad analog output but decent digital output. Another case might be where you do not care about gaming at all and just want to give your speakers PCM stereo or pass digital streams to offload the burden of decoding to your speakers. I fall into this category myself as I really don't game much and the vast majority of my usage is just passing PCM to my Boston Acoustics AVP7 Preamp.
For someone with a computer speakers system, I would say that if you have a 5.1 analog input on the set, use it. You wont have to deal with the digital surround sound issue and if you get a decent card for analog output, it will probably do a better job than the control pod on your speakers would do with processing the signal.
Creative has also released their own external encoder, the DTS-610. Use of this box will allow for full EAX effects and still takes advantage of the analog processing of the X-fi. However, it does have its downsides too. The box will introduce some lag between video and audio due to the extra processing the audio will require to encode to the digital connection. Also, you will still be compressing the audio when encoding unlike if you had a straight digital connection. It should also be noted that some loss in quality can be expected due to conversion. The X-fi uses its D/A converters to send the signal analog out to the box then the box converts it to digital and then the speaker system uses its D/A converters to change it back to analog. In the end, this will result in no where near the quality you would get from a straight analog connection from the X-fi. Lastly, the box is rather expensive. When coupled with the price of an X-fi, you are talking about a serious investment.
There are some cases where connecting via digital is pretty much your only option. On some speaker systems, decoding a DD / DTS stream is your only option to get output from all the speakers. For example, Klipsch's GMX-D 5.1 set or if you're connecting to a home theater and your receiver does not have a 5.1 analog input. In these cases you're pretty much forced to get something that can encode DD / DTS if you want to game and use surround sound. Note that often you can kind of get "fake surround" going if you give a set like this a stereo signal (either with PCM digital or stereo analog). You might apply Dolby Prologic II or DTS Neo:6. These options would have your system take that stereo signal and then kind of fake 5.1 output out of it. You'll get output from all your speakers and it will often do a good job centering voices to the center channel and so forth... but it's not going to get you the true surround sound experience you'll want for gaming.
6. Help, it's only playing on 2 speakers
Ok, this one isn't really related to digital necessarily, but it comes up often enough.
4/5 times, the solution to this "problem" seems to be that people do not use a multichannel source when they are trying to test their surround sound system. If you use standard music to test out your system, unless you have some funky "fake surround" option enabled, you should just get output from your front two speakers and the subwoofer.
Music is a stereo source (unless you're talking DVD-A etc.) so it should only play out of your two fronts and the sub. Some people want to have music play out all their speakers, and if you want to that's fine too. If you have never tried listening to just 2.1 on your surround sound system, I would suggest you try it. By listening in stereo, you preserve the soundstage of the original recording and you get playback as it was meant to be experienced.
"Fake surround" options like Creative's CMSS or Dolby Prologic II can give you surround sound out of stereo sources like music, but they can do more harm than good.
Ok... what if you're using a surround source to test your speakers and you still only get 2.1 output? Well... then we're probably going to need more info to try to figure it out
7. Cables / Connections
Ok, so you've got your digital and your analog signals.
Digital signals are carried by either a digital optical (toslink) cable of a digital coaxial cable.
For practical purposes, the signal and sound quality should be basically the same with either one you use.
For digital optical, there is the added benefit that it's basically eliminating ground loop / EM interference along the cable. The downside is there used to be some issues with jitter with some early designs, but everything appears to be worked out now.
For digital coaxial, one benefit is you might even already have a cable you can use. It's just a 75ohm RCA cable, so a yellow video RCA cable should be exactly the type of cable you want. Advantages to digital coaxial would be that it's often a more robust connection and cable than your typical toslink cable.
For analog audio, normally cables are built in to computer speakers systems or they come with the system. If you want to connect analog to a receiver, you just need to get some adapters to go from 3.5mm to RCA. One of those would get you a stereo signal while three of them connected to a 5.1 input from three analog outputs on you soundcard would get you true surround sound.
In addition to Cablesforless, there is also Monoprice as a source for affordable cables.
8. Bit-Perfect Info
Link to more info added from The Boston Dangler about bit-perfect playback
http://www.mp3car.com/vbulletin/showthread.php?t=88852
Post in here if you want me to add any more topics to this thread or if you want to correct me on anything I've said
2. Disadvantages of digital
3. Advantages of digital
4. Soundcards
5. Digital Speaker Systems
6. Help, it's only playing on 2 speakers
7. Cables / Connections
8. Bit-Perfect Info
1. Intro
Ok, so someone has linked you to this thread to give you some info on digital audio. Just some stuff I wanted to cover before I get into specifics...
Speakers are analog. Sound information starts off in your computer as digital and at some point needs to be converted to analog before it comes out your speakers. Even "digital speakers" are analog.
DD (Dolby Digital) and DTS (from Digital Theater Systems) are both multichannel digital sound sound formats that allow multichannel audio to be compressed into a digital stream.
So as I stated above, what comes out our speakers / headphones is analog in the end, so most of the digital issues and "features" that come up are mostly related to just when this conversion happens. When people get really serious about audio, they will more often than not try to keep it analog all the way from start to finish by starting from an analog source like records (anyone remember those?
) and keeping it analog all the way along their chain of components before it ends up coming out their speakers.In the world of computers, we're all starting with digital as our source, so the options we have are mostly limited to when and how the conversion to analog is going to happen.
2. Disadvantages to Digital
Ok, so basically there are two kinds of a digital signal that a soundcard can put out. One would be PCM, which is just stereo, and the other is a compressed multichannel stream (DD or DTS).
If you want to use digital, most cards out there with a digital output will only be able to give you PCM output and pass along a previously encoded DD/DTS stream. That means that you would get the desired output from stereo sources (like music) with PCM and you'd get the desired output from pre-encoded sources (like DVD movies) with DD/DTS passthrough.
The major limitation here is when it comes to games. In the case of games, individual sound track information is not available for each channel since the sound is dynamic. Since it's not all pre-recorded, in order to output a DD/DTS stream with the proper 5.1 info, your soundcard would have to encode the surround info into a DD/DTS stream in real time.
There are cards out there than can do this now, and it is becoming more widespread. A major note here is that Creative's cards do not support DD/DTS encoding. With creative's monopoly on EAX higher than 2.0, if you do get a card that encodes multichannel digital streams, you will not get all the EAX effects that the latest Creative cards are capable of.
Ok, now that I've covered that...
Even if you do get a card that outputs digital as you desire, that's probably not going to be any better quality than a decent analog card could output... and will actually probably get you lower quality results. As you know, sound has to end up analog... so by outputting digital, all you are doing is postponing when this conversion happens. In the majority of cases I have read, people want to hook up digitally to a set of computer speakers (like Logitech z-5500s, etc.). The issue is that the control pod on the speakers is now doing the work that the soundcard would have done initially if it had been outputting analog. If you get a decent soundcard, it will probably do as good or a better job at this than the control pods on these speaker sets will do.
Also, by its very nature, DD/DTS streams are compressed audio. You're potentially giving up some quality be using these sound formats. Also, there may be slight delay in this encoding process so may experience some delay in your final sound.
3. Advantages to Digital
If you have some high quality sound components in your system, they may do a better job with a digital signal and processing it vs. what your soundcard could do in it's analog output.
If you have some high quality sound components that process digital signals and apply some calibration / equalization effects to those inputs, this may be a preferred way to connect as 5.1 analog connections tend to not have any processing done on them.
Connecting one digital cable can be more convenient than several analog cables.
If you are experiencing some ground loop problems between your computer and sound system, a digital optical connection would eliminate that issue.
If you want to connect to a receiver that lacks 5.1 analog input, digital is your only option for getting surround sound.
There is the potential for less signal interference in the transmission of a digital signal to your sound system than if you were transmitting analog.
4. Soundcards
Ok, now that I've kind of gone over some basics... what's good?
If you just want to output stereo PCM and have passthrough of DD, the Chaintech AV-710 is a great budget card. In addition to the ability to get bit-perfect digital output, the Chaintech card also has one good quality analog output on it. This would be a good card to get if you want to connect a set of 2.0/2.1 speakers for music listening or if you want those basic digital sound output options.
If you think that you want a card that encodes digital streams, you have some options. Once upon a time your only option was soundstorm audio integrated into some older motherboards, but rather recently a couple companies have started producing DDL / DTS live cards. The Turtlebeach Montego and Bluegears / HDA X-Mystique were some of the first cards out with that feature.
More recently some integrated audio solutions have started to have this feature and Auzentech has stated to come out with new products that include this feature. The X-Plosion was introduced after the X-Mystique and has added the ability to enocde DTS in real time in addition to DD. The DDL connection is compressed to 640Kbps, so DTS at 1.5Mbps should produce a better final result than the DD output. Their X-Meridian is their newest card that is in the works and concentrates more on analog output quality.
For the majority of comptuer users who use analog speakers and want good gaming performance, Creative is pretty much your main option. With deals on X-Fi in the ~$70 range, that's a solid choice on a card for most users. Especially for someone that wants to game on headphones, the X-Fi has a lot to offer. The reason to get X-Fi is for it's high quality analog audio output, it's surround headphone feature, and it's multichannel gaming abilities. By connecting to it digitally, you're really not taking advantage of most of what makes the X-Fi a good card. On a tighter budget, the older Audigy 2 cards also offer good bang for your buck for a gaming card.
One issue many people have with the digital connectivity on Creative sound cards is the upsampling algorithm it employs. The card at times takes audio and upsamples it to 48KHz and outputs that out the digital connection. Most music is 44.1KHz and upsampling is a process often looked down upon in the audio world. After years of not having an option to disable upsampling on their Audigy series of cards, X-Fi cards can be set to output bit-perfect at 44.1kHz without upsampling. This is possible in Audio Creation Mode.
There are plenty of other cards out there, most notably ones that have good analog outputs for music quality and more professional cards that have a lot mor connectivity options for inputs/outputs.
That's kind of beyond what this thread is about so go nuts on the research in your own
Just as a rule of thumb, a good starting point balancing your audio budget might be to spend twice as much (or more ) on speakers as your soundcard. If you're thinking headphones, you can get better quality for cheaper, so as long as you have a pretty good pair, X-Fi may be a good way to go if you're a gamer.
Cheesehead adds:
"IMHO, a good USB DAC (PCM2706 for USB-> I2S, and TDA1543s or the like for the DAC) is the best way to go. Cheap, too-TDA1543 DAC kits can be had for a whopping 40$ on eBay, and a USB->I2S adapter can be made for 10$.
As an added bonus, an outboard PSU is easy. Just run the TDA1543 and output stage off of a wall-wart with some big power filtering caps on it."
5. Digital Speaker Systems
Ok, so if you have a digital speaker system, is it better to use a digital connection?
As I've gone over above, in most cases probably not if you can just get a card with good analog output instead. A case where it might be a good idea is if you have integrated audio with pretty bad analog output but decent digital output. Another case might be where you do not care about gaming at all and just want to give your speakers PCM stereo or pass digital streams to offload the burden of decoding to your speakers. I fall into this category myself as I really don't game much and the vast majority of my usage is just passing PCM to my Boston Acoustics AVP7 Preamp.
For someone with a computer speakers system, I would say that if you have a 5.1 analog input on the set, use it. You wont have to deal with the digital surround sound issue and if you get a decent card for analog output, it will probably do a better job than the control pod on your speakers would do with processing the signal.
Creative has also released their own external encoder, the DTS-610. Use of this box will allow for full EAX effects and still takes advantage of the analog processing of the X-fi. However, it does have its downsides too. The box will introduce some lag between video and audio due to the extra processing the audio will require to encode to the digital connection. Also, you will still be compressing the audio when encoding unlike if you had a straight digital connection. It should also be noted that some loss in quality can be expected due to conversion. The X-fi uses its D/A converters to send the signal analog out to the box then the box converts it to digital and then the speaker system uses its D/A converters to change it back to analog. In the end, this will result in no where near the quality you would get from a straight analog connection from the X-fi. Lastly, the box is rather expensive. When coupled with the price of an X-fi, you are talking about a serious investment.
There are some cases where connecting via digital is pretty much your only option. On some speaker systems, decoding a DD / DTS stream is your only option to get output from all the speakers. For example, Klipsch's GMX-D 5.1 set or if you're connecting to a home theater and your receiver does not have a 5.1 analog input. In these cases you're pretty much forced to get something that can encode DD / DTS if you want to game and use surround sound. Note that often you can kind of get "fake surround" going if you give a set like this a stereo signal (either with PCM digital or stereo analog). You might apply Dolby Prologic II or DTS Neo:6. These options would have your system take that stereo signal and then kind of fake 5.1 output out of it. You'll get output from all your speakers and it will often do a good job centering voices to the center channel and so forth... but it's not going to get you the true surround sound experience you'll want for gaming.
6. Help, it's only playing on 2 speakers
Ok, this one isn't really related to digital necessarily, but it comes up often enough.
4/5 times, the solution to this "problem" seems to be that people do not use a multichannel source when they are trying to test their surround sound system. If you use standard music to test out your system, unless you have some funky "fake surround" option enabled, you should just get output from your front two speakers and the subwoofer.
Music is a stereo source (unless you're talking DVD-A etc.) so it should only play out of your two fronts and the sub. Some people want to have music play out all their speakers, and if you want to that's fine too. If you have never tried listening to just 2.1 on your surround sound system, I would suggest you try it. By listening in stereo, you preserve the soundstage of the original recording and you get playback as it was meant to be experienced.
"Fake surround" options like Creative's CMSS or Dolby Prologic II can give you surround sound out of stereo sources like music, but they can do more harm than good.
Ok... what if you're using a surround source to test your speakers and you still only get 2.1 output? Well... then we're probably going to need more info to try to figure it out
7. Cables / Connections
Ok, so you've got your digital and your analog signals.
Digital signals are carried by either a digital optical (toslink) cable of a digital coaxial cable.
For practical purposes, the signal and sound quality should be basically the same with either one you use.
For digital optical, there is the added benefit that it's basically eliminating ground loop / EM interference along the cable. The downside is there used to be some issues with jitter with some early designs, but everything appears to be worked out now.
For digital coaxial, one benefit is you might even already have a cable you can use. It's just a 75ohm RCA cable, so a yellow video RCA cable should be exactly the type of cable you want. Advantages to digital coaxial would be that it's often a more robust connection and cable than your typical toslink cable.
For analog audio, normally cables are built in to computer speakers systems or they come with the system. If you want to connect analog to a receiver, you just need to get some adapters to go from 3.5mm to RCA. One of those would get you a stereo signal while three of them connected to a 5.1 input from three analog outputs on you soundcard would get you true surround sound.
In addition to Cablesforless, there is also Monoprice as a source for affordable cables.
8. Bit-Perfect Info
Link to more info added from The Boston Dangler about bit-perfect playback
http://www.mp3car.com/vbulletin/showthread.php?t=88852
Post in here if you want me to add any more topics to this thread or if you want to correct me on anything I've said
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