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Finally, A Creative X-Fi Driver Going Into ALSA

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  • #16
    Originally posted by DeepDayze View Post
    I can take a gander at these...as I got an older X-Fi in my junk parts box now.
    DONT TOUCH IT!! you wouldn't search for trash would you?

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    • #17
      Sound card mods

      Originally posted by hax0r View Post
      Hmm the pic seems to be gone, damn imageshack. My and Napalm's worklog: http://www.xtremesystems.org/forums/...d.php?t=182354
      Also: http://forums.guru3d.com/showthread.php?t=255682
      No offense to Napalm, but that capacitor mod on xtremesystems has no grounding in reality. By changing the values of capacitors, he likely changed the frequency response of filters placed by the original engineer. So, even though the new capacitors have better electrical characteristics, it's entirely possible that the "better" sound Napalm experienced was just an increased treble and bass response caused by haphazardly replacing capacitors. Further, the sound card may now be emitting RF energy in excess of legal limits.

      For example, if I were designing an analog to digital input section, I might place a high pass filter with a low corner frequency to block DC (this would likely involve a capacitor in series with the signal), and a low pass filter to block signals above the ADC's limits (this would probably involve a capacitor to ground or an inductor in series). An output section will also likely require high-pass filtering because the DAC probably uses a 0V-xV range (rather than -x/2V to +x/2V), and low pass filtering for controlling RF. Changing the values of capacitors will change the frequency response of these filters.

      Secondly, the -150dB noise floor reported in one of the sound test screen shots is physically impossible to attain at room temperature and audio voltages. It looks like the program generated a test tone, then analyzed the test tone without passing it through the sound card. Also, the cross-talk spectrum shown has little or nothing to do with actual channel frequency response.


      That said, we all have to learn somehow, there are lots of things I don't know, and I don't want to discourage anyone from modding their hardware. I just don't want to see people spending hundreds of dollars on capacitors without a well-measured baseline and a clear goal for improvement. If I were to offer advice to sound card modders, it would be something like this:
      1. If you don't know what a particular capacitor is doing in the circuit, replace it with the same capacitance value (you don't change the capacitance if you change voltages -- the frequency response of a simple filter depends only on R and C, not the input voltage).
      2. Always measure before and after!
      3. Make sure you know how to use your measurement software. RoomEqWizard is a very good cross-platform tool.
      4. Your target should be a flat frequency response from the sound card.
      5. Clean the signal path first. Find the components that directly touch the signal (you may have to look up pin diagrams of the chips on the card, or carefully probe the card with a scope), and replace those first. This would include the op-amps.
      6. Next, look at your power supply. Changing capacitor values here might make sense, if you know what you're doing. You essentially want a very low frequency low pass filter to block anything that isn't DC from going to the power input lines of the ADC, DAC, clock generator (if any) and op-amps. Chip manufacturers will often specify what capacitance to use and where to put it.
      7. Finally, you might be able to improve the clock circuit to reduce jitter, though the power improvements would probably have already helped here.
      8. Don't put capacitors in series to reduce capacitance. It works, but an former coworker who's been designing pro audio equipment for years said that it can lead to one of the capacitors failing.
      9. Final thought: increasing the output voltage of the sound card (by changing the resistors that govern the op-amp gain) may reduce the relative noise level picked up by long cables to your power amplifier, but may also overdrive other components. Make sure you're well within the voltage supply rails of the op-amps.

      Recommended Google search terms for learning: "analog filter design", "RC filter design", "RC filter cutoff frequency", "RC time constant", "2nd-order filter design", "RC filter frequency response". Read the Wikipedia pages about filters, resistors, capacitors, and op-amps.

      Comment


      • #18
        Originally posted by unix_epoch View Post
        No offense to Napalm, but that capacitor mod on xtremesystems has no grounding in reality. By changing the values of capacitors, he likely changed the frequency response of filters placed by the original engineer. So, even though the new capacitors have better electrical characteristics, it's entirely possible that the "better" sound Napalm experienced was just an increased treble and bass response caused by haphazardly replacing capacitors. Further, the sound card may now be emitting RF energy in excess of legal limits.

        For example, if I were designing an analog to digital input section, I might place a high pass filter with a low corner frequency to block DC (this would likely involve a capacitor in series with the signal), and a low pass filter to block signals above the ADC's limits (this would probably involve a capacitor to ground or an inductor in series). An output section will also likely require high-pass filtering because the DAC probably uses a 0V-xV range (rather than -x/2V to +x/2V), and low pass filtering for controlling RF. Changing the values of capacitors will change the frequency response of these filters.

        Secondly, the -150dB noise floor reported in one of the sound test screen shots is physically impossible to attain at room temperature and audio voltages. It looks like the program generated a test tone, then analyzed the test tone without passing it through the sound card. Also, the cross-talk spectrum shown has little or nothing to do with actual channel frequency response.


        That said, we all have to learn somehow, there are lots of things I don't know, and I don't want to discourage anyone from modding their hardware. I just don't want to see people spending hundreds of dollars on capacitors without a well-measured baseline and a clear goal for improvement. If I were to offer advice to sound card modders, it would be something like this:
        1. If you don't know what a particular capacitor is doing in the circuit, replace it with the same capacitance value (you don't change the capacitance if you change voltages -- the frequency response of a simple filter depends only on R and C, not the input voltage).
        2. Always measure before and after!
        3. Make sure you know how to use your measurement software. RoomEqWizard is a very good cross-platform tool.
        4. Your target should be a flat frequency response from the sound card.
        5. Clean the signal path first. Find the components that directly touch the signal (you may have to look up pin diagrams of the chips on the card, or carefully probe the card with a scope), and replace those first. This would include the op-amps.
        6. Next, look at your power supply. Changing capacitor values here might make sense, if you know what you're doing. You essentially want a very low frequency low pass filter to block anything that isn't DC from going to the power input lines of the ADC, DAC, clock generator (if any) and op-amps. Chip manufacturers will often specify what capacitance to use and where to put it.
        7. Finally, you might be able to improve the clock circuit to reduce jitter, though the power improvements would probably have already helped here.
        8. Don't put capacitors in series to reduce capacitance. It works, but an former coworker who's been designing pro audio equipment for years said that it can lead to one of the capacitors failing.
        9. Final thought: increasing the output voltage of the sound card (by changing the resistors that govern the op-amp gain) may reduce the relative noise level picked up by long cables to your power amplifier, but may also overdrive other components. Make sure you're well within the voltage supply rails of the op-amps.

        Recommended Google search terms for learning: "analog filter design", "RC filter design", "RC filter cutoff frequency", "RC time constant", "2nd-order filter design", "RC filter frequency response". Read the Wikipedia pages about filters, resistors, capacitors, and op-amps.
        Thanks for taking you time to write this, I appreciate wisdom .
        Yeah Napalm seems to go extreme with the capacitance, but he always tests out 20 different values and chooses what sounds the best. I myself used Panasonic FM series and Rubycon ZL & BlackGates caps matched to original the capacitance, the only ones that were %300 or %500 of the original are the DC filtering caps. My amps is alive and well (fingers crossed!), also kinda cool that you mentioned terms such RC circuits and time constant, all of these things I learned and did labs in my physics classes . You got me thinking, next time when I mod a soundcard I will get a hold of oscilloscope and measure frequency. Hmm can elaborate more on the emitted RF energy? Sounds interesting.

        Comment


        • #19
          Originally posted by hax0r View Post
          Thanks for taking you time to write this, I appreciate wisdom .
          Yeah Napalm seems to go extreme with the capacitance, but he always tests out 20 different values and chooses what sounds the best. I myself used Panasonic FM series and Rubycon ZL & BlackGates caps matched to original the capacitance, the only ones that were %300 or %500 of the original are the DC filtering caps. My amps is alive and well (fingers crossed!), also kinda cool that you mentioned terms such RC circuits and time constant, all of these things I learned and did labs in my physics classes . You got me thinking, next time when I mod a soundcard I will get a hold of oscilloscope and measure frequency. Hmm can elaborate more on the emitted RF energy? Sounds interesting.
          Napalm could save a lot of listening time by mathematically analyzing the circuit (or at least measuring it) and ensuring a flat frequency response and suitable noise+distortion measurements (if you can hear it, you can measure it!). The easiest way to measure a sound card's frequency performance is to hook the line out to the line in, and run a frequency sweep with Room EQ Wizard. You can also build the circuit in a simulator, like Qucs, and measure its expected ideal response there. Other than that,you can look for a dedicated hardware audio measurement system, such as the one my previous employer used: the Audio Precision line of test tools, which can run in the tens of thousands of dollars per unit (there are cheaper tools available). If you have an oscilloscope that will display a frequency spectrum, you could output white noise from the sound card and feed it into the scope, but that won't provide as much detail as a nice, long sine sweep.

          As for RF energy, the various clocks on a sound card operate at frequencies up to the MHz range. Without proper filtering, these clocks (and their harmonics and subharmonics) can leak through the DACs into the output signal, and then be emitted into the air by your cables (which act as transmitting antennas). You can check for unwanted frequencies on the wire using a high bandwidth spectrum analyzer. You can also go to the expense of building a shielded room (my previous employer had one), complete with RF test equipment, if you're feeling a bit crazy.

          Comment


          • #20
            Finally something good from Creative.

            I Wonder does it work with Auzentech's cards, they are based x-fi chips...?

            Comment


            • #21
              Hrm.

              I always thought that the quality of analog output rested mostly with the DAC chips on the sound card, were as those mods seem mostly to center around conditioning the power delivery.

              Better DAC, better sound. That's about it.




              Personally, for the best quality, I just did SPDIF-OUT for a full digital path from my audio file being decoded into my Sony "home theater" stereo receiver then hooked my headphones up to that. I don't need a fancy card for that... Intel-HDA works as well as anything since it does zero processing to the sound at that point.

              In fact that is quite a bit better then my old Audigy. As part of the hardware mixing features of the sound card the Audigy remixed the audio stream to it's prefered format no matter what you did.. unless it was Ac3 passthough or whatever.

              As for RF energy, the various clocks on a sound card operate at frequencies up to the MHz range. Without proper filtering, these clocks (and their harmonics and subharmonics) can leak through the DACs into the output signal, and then be emitted into the air by your cables (which act as transmitting antennas). You can check for unwanted frequencies on the wire using a high bandwidth spectrum analyzer. You can also go to the expense of building a shielded room (my previous employer had one), complete with RF test equipment, if you're feeling a bit crazy.
              Well the electrical magnetic radiation is trapped in your computer case by fact that it's a metal box. Every little circuit and clock and proccessor in your computer is just screaming with radio waves. And then there is a crapload of fast signaling going around on the cables inside your case for the harddrive connections and whatnot. (of course the radiation going into the case and into the sound card is going to leak out the coax for your audio output!)

              So the radiation is going to have the biggest effect actual analog circuits of your sound card then on the wiring on the outside of the case. So any sort of analog circuit inside the computer is automatically at a huge disadvantage and is subject to all sorts of problems.

              You could probably make a metal case around your sound card, but it's going to be difficult to make sure it's properly grounded as much as possible so that it doesn't act like a great big antenna. (copper tape works wonders)

              This is the main reason why, for best sound quality, I prefer to run a digital output to a external receiver, which then does the digital to analog transformation. But I still wouldn't mind a very very nice audio card.

              Probably the best sound for a mobile system is probably a high quality USB sound card. Sure you have high latency, but that is not important for playback. I don't have one to recommend, right now... most usb audio is cruddy, but there are some nice ones out there.
              Last edited by drag; 05-15-2009, 05:37 AM.

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              • #22
                At last I can swap out my audigy 2 with my nice new x-fi!

                Don't worry, you didn't make me wait as long as Duke Nukem Forever or TF2 <3

                Comment


                • #23
                  Originally posted by drag View Post
                  Hrm.

                  I always thought that the quality of analog output rested mostly with the DAC chips on the sound card, were as those mods seem mostly to center around conditioning the power delivery.

                  Better DAC, better sound. That's about it.
                  Well you would be wrong. After the DAC filtering and preout stage has much to do with the overall sound quality. Hook up the finest DAC you want to a shitty preout stage and experience the ultimate in disappointment. In fact you will notice more of a degredation in sound from the quality of the preout then you will with the quality of the DAC. Having too small of caps on the outs for example will often result in a "muddy" bass. The DAC is just one part of the equation. Like anything else in audio your only as good as the weakest part in the chain.

                  Comment


                  • #24
                    Seeing as you have one of these cards...

                    Originally posted by hax0r View Post
                    Works flawlessly:
                    Can you also post the contents of /proc/asound/card0/pcm?p/info please? (Assuming that your X-Fi is card0.) I am interested in how many hardware channels the X-Fi has. I'm guessing this is another card that does hardware mixing?

                    Comment


                    • #25
                      Not to derail the tread, but never grasped hardware mixing. I know it's a good thing to have, but what I want to know is what chips/cards have it. Is it safe to assume that all dedicated sound processors have hardware mixing and that integrated solutions do not? That was my general understanding, until I read somewhere that he ASUS Xonar lacks hardware mixing. The ALSA card matrix is not that helpful in determining what supported cards have hardware mixing (only some Creative cards seem to have the tag).

                      Comment


                      • #26
                        This is GREAT news! Let's hope Creative doesn't frak it up like they usually do :/

                        I'm a relative noob to using linux for audio processing because of the whole X-fi deal, I've only recently learned the Jack audio system and am completely blown away by the flexibility and features and am looking forward to dumping MS completely.

                        If these driver do in fact work flawlessly, then I am ready to dump MS right freakin' now, even with a "beta-ish" driver. My only problem is the install process.

                        Again, I'm a noob so please don't beat me up if I ask how to install these. I've got the file downloaded and ran "su make" then "install" or something like that and it did something in the terminal. I see the Creative ALSA driver in AUDIO, am I good to go?? Am I ready to play DVDs in surround, 5.1 channel games, . . etc???

                        Thanks

                        Comment


                        • #27
                          Originally posted by Melcar
                          Not to derail the tread, but never grasped hardware mixing. I know it's a good thing to have, but what I want to know is what chips/cards have it. Is it safe to assume that all dedicated sound processors have hardware mixing and that integrated solutions do not? That was my general understanding, until I read somewhere that he ASUS Xonar lacks hardware mixing. The ALSA card matrix is not that helpful in determining what supported cards have hardware mixing (only some Creative cards seem to have the tag).
                          It's a feature of some high-end chips, and it was more popular a few years ago than now. It basically both works and doesn't use cpu, and both of those have nearly become moot with faster processors and better drivers (remember when you couldn't listen to more than one stream with ALSA? That's when HW mixing was useful).

                          Nowadays it's IMO useful if one needs low-latency audio, as a dedicated mixing chip works faster/better than a software solution.

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                          • #28
                            ^^^^^
                            a realtime recording interface such as MIDI, CREOX, or JackRack would be a one example of where low-latency would be beneficial.

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                            • #29
                              I really miss the hw mixer in the current X-Fi drivers.
                              As far as I understand this would provide global bass/treble
                              mixer controls as it did with my old SB Live. Not sure though...

                              Does anybody know how one can get a globally working equalizer?
                              I once stumbled across a plug-in for pulse audio that I couldn't get to work.

                              Comment


                              • #30


                                The DVD 5.1 audio works pretty well in VLC with only minor headaches after fraking around with it a bit,

                                Some stupid error pops up after choosing 5.1 under "audio device" but it doesn't seem to affect the audio at all. The settings don't save in VLC which may be because of my noobified installation, but the 5.1 sounds pretty rawkin'! Bill Gates can suck it

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