Hi Amo,
I was concerned about the same sort of issues you are raising and used shielded ata cables and dressed the atx power cables out of the way.
Although I think the grounding techniques used in most pc's are questionable I think doing something substantially different may actually make the situation worse in some instances and none of us have the required equipment to verify whether the changes helped or hindered.
Also mu-metal is used for magnetic shielding not electrostatic shielding which is what is mainly going to be the issue in your pc except around a few large filter inductors in the power supply on the mobo.. Also mu-metal looses its magnetic shielding properties when formed to shape and has to be re-annealed in a high temp oven after forming in order to retain its magnetic shielding properties. Most RFI shields are made of plated tin.
I would shield the audio card if possible, and if using spdif out I would choose a card with a transformer or add one to the existing spdif output to provide some common mode isolation from PC noise to devices connected to the output. A good common mode choke prior to the transformer would also be a good idea. The spdif output would probably float and not be connected to the case at all or if needed could be grounded just at the case bracket.
Based on my so far limited experience I don't think there is much of an issue with noise inside the pc.
I am using unfiltered spdif output from the mobo, and despite my reservations about the hardware quality with ASIO running it sounds quite good, and for now is good enough.
I plan to make a little spdif card with the cm choke, a cap, some resistors and the transformer and drill a small hole in the case for an isolated bnc which will free up a much needed card slot for something else.
I started this thread as a discussion of issues I was trying to address in the design of my server, so just about anything goes here as long as it is in some way related. Your topic was & is relevant..
Kevin
I was concerned about the same sort of issues you are raising and used shielded ata cables and dressed the atx power cables out of the way.
Although I think the grounding techniques used in most pc's are questionable I think doing something substantially different may actually make the situation worse in some instances and none of us have the required equipment to verify whether the changes helped or hindered.
Also mu-metal is used for magnetic shielding not electrostatic shielding which is what is mainly going to be the issue in your pc except around a few large filter inductors in the power supply on the mobo.. Also mu-metal looses its magnetic shielding properties when formed to shape and has to be re-annealed in a high temp oven after forming in order to retain its magnetic shielding properties. Most RFI shields are made of plated tin.
I would shield the audio card if possible, and if using spdif out I would choose a card with a transformer or add one to the existing spdif output to provide some common mode isolation from PC noise to devices connected to the output. A good common mode choke prior to the transformer would also be a good idea. The spdif output would probably float and not be connected to the case at all or if needed could be grounded just at the case bracket.
Based on my so far limited experience I don't think there is much of an issue with noise inside the pc.
I am using unfiltered spdif output from the mobo, and despite my reservations about the hardware quality with ASIO running it sounds quite good, and for now is good enough.
I plan to make a little spdif card with the cm choke, a cap, some resistors and the transformer and drill a small hole in the case for an isolated bnc which will free up a much needed card slot for something else.
I started this thread as a discussion of issues I was trying to address in the design of my server, so just about anything goes here as long as it is in some way related. Your topic was & is relevant..
Kevin
I have started to rip cds to flac and have found that not using the replaygain setting in flac results in a better sounding file. I also am using the playlists created in EAC and editing them in notepad where I use replace all to replace the .wav extensions in the playlist with .flac extensions so that the original order of the album is preserved.
Sound quality is definitely very good on 16bit cd's, unfortunately it appears something is stripping the HDCD subcode from the HDCD's I have so instead of playing back with 20 bits they playback at 16 bits. I suspect this problem might be EAC, but to be sure I will rip one or two HDCD songs to wav files and test them.
Has anyone successfully ripped and converted to flac with the HDCD subcode intact and if so how did you do it?
Kevin
Sound quality is definitely very good on 16bit cd's, unfortunately it appears something is stripping the HDCD subcode from the HDCD's I have so instead of playing back with 20 bits they playback at 16 bits. I suspect this problem might be EAC, but to be sure I will rip one or two HDCD songs to wav files and test them.
Has anyone successfully ripped and converted to flac with the HDCD subcode intact and if so how did you do it?
Kevin
I have done a little further research into the question of HDCD ripping, according to what I have read both EAC and FLAC support it, and the spdif output of the ALC650 in my mobo purports to support it as well.
I have a PS Audio Ultralink II which supports HDCD playback. Last night after my last post I ripped an HDCD to wav file and observed that the DAC did not indicate it was HDCD encoded. I them converted it to flac and noted no difference in behavior.
I will decode the flac file back to wav and use Nero to burn a copy and see if that is recognized as an HDCD as the next step. I also have a flac pluggin for Nero which I will not use for this experiment, but will test later.
Open questions re HDCD:
Flac reference decoder plugin for Winamp
Flac plugin for Nero
Asio_out.dll plugin for Winamp
Flac
EAC
Asio4all
ALC650E Spdif output
The DAC works fine in HDCD mode with the Sony SACD player I use as a transport for playing CDs now that the Lambda is dead.
Kevin
I have a PS Audio Ultralink II which supports HDCD playback. Last night after my last post I ripped an HDCD to wav file and observed that the DAC did not indicate it was HDCD encoded. I them converted it to flac and noted no difference in behavior.
I will decode the flac file back to wav and use Nero to burn a copy and see if that is recognized as an HDCD as the next step. I also have a flac pluggin for Nero which I will not use for this experiment, but will test later.
Open questions re HDCD:
Flac reference decoder plugin for Winamp
Flac plugin for Nero
Asio_out.dll plugin for Winamp
Flac
EAC
Asio4all
ALC650E Spdif output
The DAC works fine in HDCD mode with the Sony SACD player I use as a transport for playing CDs now that the Lambda is dead.
Kevin
Haven't yet resolved the question of HDCD.
Downloaded and installed FOO as a media player yesterday, still have to install and configure ASIO as the output device for this player.
Turns out that for those of you who have been baffled by Otachan's asio files as I was, they are actually zipped with 7-zip found at http://7-zip.org. I have never heard of this version of zip which obviously is not recognized by windows, apparently microsoft has never heard of it either - so I don't feel so bad. Very, very annoying.
The extension for this obscure file format is .7z...
Do we really need yet another incompatible zip format??
I wish someone would mirror otachan's website in English as these drivers don't appear to be available anywhere else and there is no English language version available.
The upshot of it is that I will be able to upgrade to a much more recent version of ASIO for Winamp tonight as well as install the latest ASIO driver for FOO as well.
Foo is a very simple media player with a stripped down interface. Seems quite robust. I am going to experiment with it and see if it has any effect good or otherwise on the sound of my FLAC files.
Also I suspect that the mobo SPDIF output isn't that great. It sounds pretty harsh for about the first half hour or so and then things smooth out considerably. I will probably start the quest for a decent sound card with spdif output again shortly.
The outboard DAC is always powered and the other equipment is all tube and sounds relatively innocuous even when cold.
TV tuner card came, still no S video adaptor for the mobo so video recording will have to await its arrival.
So far everything basically works, and there are no major issues other than the HDCD issue.
Kevin
Downloaded and installed FOO as a media player yesterday, still have to install and configure ASIO as the output device for this player.
Turns out that for those of you who have been baffled by Otachan's asio files as I was, they are actually zipped with 7-zip found at http://7-zip.org. I have never heard of this version of zip which obviously is not recognized by windows, apparently microsoft has never heard of it either - so I don't feel so bad. Very, very annoying.
The extension for this obscure file format is .7z...
Do we really need yet another incompatible zip format??
I wish someone would mirror otachan's website in English as these drivers don't appear to be available anywhere else and there is no English language version available.
The upshot of it is that I will be able to upgrade to a much more recent version of ASIO for Winamp tonight as well as install the latest ASIO driver for FOO as well.
Foo is a very simple media player with a stripped down interface. Seems quite robust. I am going to experiment with it and see if it has any effect good or otherwise on the sound of my FLAC files.
Also I suspect that the mobo SPDIF output isn't that great. It sounds pretty harsh for about the first half hour or so and then things smooth out considerably. I will probably start the quest for a decent sound card with spdif output again shortly.
The outboard DAC is always powered and the other equipment is all tube and sounds relatively innocuous even when cold.
TV tuner card came, still no S video adaptor for the mobo so video recording will have to await its arrival.
So far everything basically works, and there are no major issues other than the HDCD issue.
Kevin
Here's the latest since I can see a lot of people are reading this thread if not participating..
I successfully installed the latest version of Otachan's ASIO DLL for FOO last night and I could hear an immediate improvement, that is once I disabled the DSP based volume control in FOO. For whatever reason it was responsible for some fairly audible crunchy sounding distortion (ain't subjectivism wonderful ) in the high frequencies.
FOO seems like a good way to go in terms of a media player, it generates tabbed playlists which I think is useful if you are playing albums. The interface is very simple to the point of being barebones, but the program itself seems to be very robust and stable and will run even with broken 3rd party dlls and other ills. I also like the fact that it is open source freeware. The name is pretty strange.
Since I could not find an audio card I liked I have decided to design & build an outboard USB dac and spdif/aes/ebu interface for the music server. Right now I am planning on using a PCM2707 for USB to I2S, PCM1794 D/A, and DIT4192 for SPIF/AES support. THe PCM2707 provides all of these functions internally, but I think the overall performance can be slightly improved by externalizing the functions, and in any case the 1794 is a better D/A than the one provided in the 2707. I will use a precision 12.000MHz oscillator on the 2707 instead of the usual cheap mpu crystal typically used. (The internal PLL uses the system clock to synthesize all of the audio clocks as well as those used by the USB client.)
In the mean time I am building a box containing common mode filtering and a pulse transformer for the spdif output to provide some isolation from computer generated noise and to break a potential ground loop that will happen when I add the tv tuner card and s-video output card.
I have ripped about 10 cd's so far and the results are getting better as I learn how to optimize the ripping/conversion parameters. I may go back and replace a few of the early cds with new rips.
That's about it for the moment.
Kevin
I successfully installed the latest version of Otachan's ASIO DLL for FOO last night and I could hear an immediate improvement, that is once I disabled the DSP based volume control in FOO. For whatever reason it was responsible for some fairly audible crunchy sounding distortion (ain't subjectivism wonderful
) in the high frequencies.FOO seems like a good way to go in terms of a media player, it generates tabbed playlists which I think is useful if you are playing albums. The interface is very simple to the point of being barebones, but the program itself seems to be very robust and stable and will run even with broken 3rd party dlls and other ills. I also like the fact that it is open source freeware. The name is pretty strange.
Since I could not find an audio card I liked I have decided to design & build an outboard USB dac and spdif/aes/ebu interface for the music server. Right now I am planning on using a PCM2707 for USB to I2S, PCM1794 D/A, and DIT4192 for SPIF/AES support. THe PCM2707 provides all of these functions internally, but I think the overall performance can be slightly improved by externalizing the functions, and in any case the 1794 is a better D/A than the one provided in the 2707. I will use a precision 12.000MHz oscillator on the 2707 instead of the usual cheap mpu crystal typically used. (The internal PLL uses the system clock to synthesize all of the audio clocks as well as those used by the USB client.)
In the mean time I am building a box containing common mode filtering and a pulse transformer for the spdif output to provide some isolation from computer generated noise and to break a potential ground loop that will happen when I add the tv tuner card and s-video output card.
I have ripped about 10 cd's so far and the results are getting better as I learn how to optimize the ripping/conversion parameters. I may go back and replace a few of the early cds with new rips.
That's about it for the moment.
Kevin
I have setup a music server with 160G using the TVIX module. I have already rip a few dozen cd and the digital output is excellent. My friend has compare this to his fully Blackgated heavy-weight Sony 777 and he found the TVIX to be smoother than the Sony but lose on the bass.
You'll need to connect to a monitor for the display however.
Does anybody else have experience on this product?
You'll need to connect to a monitor for the display however.
Does anybody else have experience on this product?
Here's the latest news.
Most of the bugs are resolved, however I have yet to resolve the HDCD format issue.. I should have burned that test cd by now, but haven't - I really don't have an excuse.. Well I do actually, other hifi hardware problems unrelated to the server. (Nummie broke his pre-amplifier - now happily fixed, ah the joys of DIY!)
A number of people on the hydrogenaudio forum have stated quite categorically that all AC97 codecs resample to 48kHz, and if true this would account for my not being able to play HDCD encoded material back in HDCD.
I think I can test this hypothesis by temporarily using my m-audio transit as a spdif (optical only unfortunately) source. The transit supports asio directly..
OT:
If you join and post to the afore mentioned forum be aware that if you make an unsubstantiated remark or error in your post other members will quickly use the warn button on you. I made a factual error in one of my early posts, got warned and suspended for 3 days as a result. I now have a warning level of 33% and assume it could get worse.. It's not a place to express your opinions...
Most of the bugs are resolved, however I have yet to resolve the HDCD format issue.. I should have burned that test cd by now, but haven't - I really don't have an excuse..
Well I do actually, other hifi hardware problems unrelated to the server. (Nummie broke his pre-amplifier - now happily fixed, ah the joys of DIY!) A number of people on the hydrogenaudio forum have stated quite categorically that all AC97 codecs resample to 48kHz, and if true this would account for my not being able to play HDCD encoded material back in HDCD.
I think I can test this hypothesis by temporarily using my m-audio transit as a spdif (optical only unfortunately) source. The transit supports asio directly..
OT:
If you join and post to the afore mentioned forum be aware that if you make an unsubstantiated remark or error in your post other members will quickly use the warn button on you. I made a factual error in one of my early posts, got warned and suspended for 3 days as a result. I now have a warning level of 33% and assume it could get worse..
It's not a place to express your opinions...
Well I have confirmed that AC97 codecs do usually resample everything to 48kHz and in the case of the codec used on my mobo - a Realtec part. the resampling cannot be defeated. I installed my m-audio transit as the audio interface to my dac and I am now able to play HDCD encoded material in HDCD mode.
Kevin
Kevin
Last night I ordered an M-Audio 2496 pci sound card which provides unresampled spdif output as well as 24 bit 96kHz codecs so I will see how that goes...
Still waiting on the Asus AV/S and am beginning to think it will be on perpetual back order.. Still I wanted to give the onboard video a try before investing in a more expensive AGP card. If it is anything like the audio on this motherboard it will just miss the target by a smidge..
I will hold off on purchasing Sage until the time I have the hardware..
Kevin
Still waiting on the Asus AV/S and am beginning to think it will be on perpetual back order.. Still I wanted to give the onboard video a try before investing in a more expensive AGP card. If it is anything like the audio on this motherboard it will just miss the target by a smidge..
I will hold off on purchasing Sage until the time I have the hardware..
Kevin
Well after a week of horrors with the Audiophile 2496 I am finally able to output a clean, unprocessed pcm stream via spdif which when HDCD encoded plays back in HDCD..
Using ASIO go to the player plugin and offset the output channels from "0" to "2" this selects the Audiophile's WavOut S/PDIF output channel.
Simply go to the Patchbay/Router panel and under HW Out S/PDIF select WavOut S/PDIF, that's it..
If successful you will see the mixer/monitor WavOut S/PDIF meters indicating signal level.
Don't use the mixer to send signals to spdif as although very good 32 bit hardware it did damage the pcm stream enough to cause erratic HDCD mode detection in my external DAC.
No one at M-Audio could tell me this, I had to figure it out on my own.
I won'y go into the various suggestions made, but I did forward essentially the same information to them.
Incidentally I am now using QCD which to my knowledge is the only player that advertises the fact that it has ASIO support. The plugin can be downloaded right from their site and installs automatically. I have always loved this player and hesitated to use it due to my uncertainty as to whether it supported FLAC (it does) and ASIO (it does.)
The Haupauge TV tuner is installed, all the stands in the way of using it is my inability to get the ASUS AV/S I need to output S-video from my mobo. The onboard video is very good for movie playback on my LCD monitor so I don't want another video card, just the adaptor..
Kevin
Using ASIO go to the player plugin and offset the output channels from "0" to "2" this selects the Audiophile's WavOut S/PDIF output channel.
Simply go to the Patchbay/Router panel and under HW Out S/PDIF select WavOut S/PDIF, that's it..
If successful you will see the mixer/monitor WavOut S/PDIF meters indicating signal level.
Don't use the mixer to send signals to spdif as although very good 32 bit hardware it did damage the pcm stream enough to cause erratic HDCD mode detection in my external DAC.
No one at M-Audio could tell me this, I had to figure it out on my own.
I won'y go into the various suggestions made, but I did forward essentially the same information to them.
Incidentally I am now using QCD which to my knowledge is the only player that advertises the fact that it has ASIO support. The plugin can be downloaded right from their site and installs automatically. I have always loved this player and hesitated to use it due to my uncertainty as to whether it supported FLAC (it does) and ASIO (it does.)
The Haupauge TV tuner is installed, all the stands in the way of using it is my inability to get the ASUS AV/S I need to output S-video from my mobo. The onboard video is very good for movie playback on my LCD monitor so I don't want another video card, just the adaptor..
Kevin
Very nice work guys. Quick question: Can someone describe the process or the path of data from the CD to the hard drive when ripping music? For example: “the drive reads the CD, applying C1/C2 (and other) error detection. Data arrives through the IDE bus and is stored in general memory allocated to the software which is ripping the CD. The software then writes the data to file on the hard drive.” What I am looking for here is the details of what happens to the data between the CD drive and the memory. Also, is the description above even correct? I am trying to understand if this is a strict data-only transaction, or if the CD drive produces music, and the software converts the music to data, and if this is the case, then how is this done? Can there be up-sampling, etc… Does all this happen in the CD drive, or does the conversion happen in the software? Thanks for your help.
Someone on Hydrogenaudio should be able to explain the process a lot more accurately than I can, or the process may already be described in a FAQ there. I would best leave it to one of the experts at Hydrogenaudio to describe in detail.
Note however that the data on the disk is not converted to analog. Everything is done in the digital domain. Drives that will play audio cd's have some hardware decoding/error correction supporting circ (cross-interleaved reed solomon code) and output a decoded serial data stream which is then written to the hard drive usually by a dma transaction. Some ripping software like EAC will tell the drive to continue to read until valid data is read and can be verified. This is about the level of my knowledge.. LOL
I can tell you from experience that sound quality can be comparable/equal to a very good cd transport with the right software and hardware.
Kevin
Edited, removed some descriptive information that might be more accurately described elsewhere.
Note however that the data on the disk is not converted to analog. Everything is done in the digital domain. Drives that will play audio cd's have some hardware decoding/error correction supporting circ (cross-interleaved reed solomon code) and output a decoded serial data stream which is then written to the hard drive usually by a dma transaction. Some ripping software like EAC will tell the drive to continue to read until valid data is read and can be verified. This is about the level of my knowledge.. LOL
I can tell you from experience that sound quality can be comparable/equal to a very good cd transport with the right software and hardware.
Kevin
Edited, removed some descriptive information that might be more accurately described elsewhere.
amo said:
The most detailed information on reading data off the disc is in the INF/MMC/ATAPI specs but they are a pretty dense read and only cover getting data off the disc and onto the bus. For a less dense but informative article see here.
http://www.xiph.org/paranoia/faq.html#play
I finally suceeded in getting the AV/S adaptor I need for my mother board. I expect it will arrive sometime next week and I will install it then.
I plan to use SAGe for the PVR function and judging from the amount of space I have already used storing CDs in flac format I will probably need to add another HD shortly. I recommend using a larger drive than the 80MB drive I am using particularly if the media server is to be used for more than music serving.
In the meantime I have suceeded in getting the system sound output via spdif and all other sources (except video player) output their audio via spdif.
Another comment I ran into frequently was that I did not need as much computational power as this machine has, however I have not found this to be true. I frequently rip and encode to flac while listening to music as I don't have time to do them independently. I have set ASIO thread priority to "time critical" and the player is set to the highest resource priority setting as well to avoid interruptions in the sound while other processing is occuring. Note that even with the Athlon XP 2600 flac encoding a single disk while playing music can take more than 5 minutes. No encoding errors have occured so far, so this is the way I maximize my time/value trade off... LOL
Incidentally to avoid ground loops the output of the 2496 is connected to a spdif transformer before being fed into the dac. To increase common mode noise rejection there is also a coilcraft cm choke between the pc and that spdif transformer.
I hope to be able to use the analog inputs to rip lps to the HD at some point as well, however this is a low priority at the moment.
I will eventually build an external 2496 dac using the crystal CS8416 spdif receiver and the bb pcm1798 dac. Plan is to use this with sample rate conversion to 96K for conventional pcm file playback and use the ultralink primarily for HDCD playback.
Once I get the AV/S installed I will provide further updates of progress if any...
Kevin
I plan to use SAGe for the PVR function and judging from the amount of space I have already used storing CDs in flac format I will probably need to add another HD shortly. I recommend using a larger drive than the 80MB drive I am using particularly if the media server is to be used for more than music serving.
In the meantime I have suceeded in getting the system sound output via spdif and all other sources (except video player) output their audio via spdif.
Another comment I ran into frequently was that I did not need as much computational power as this machine has, however I have not found this to be true. I frequently rip and encode to flac while listening to music as I don't have time to do them independently. I have set ASIO thread priority to "time critical" and the player is set to the highest resource priority setting as well to avoid interruptions in the sound while other processing is occuring. Note that even with the Athlon XP 2600 flac encoding a single disk while playing music can take more than 5 minutes. No encoding errors have occured so far, so this is the way I maximize my time/value trade off... LOL
Incidentally to avoid ground loops the output of the 2496 is connected to a spdif transformer before being fed into the dac. To increase common mode noise rejection there is also a coilcraft cm choke between the pc and that spdif transformer.
I hope to be able to use the analog inputs to rip lps to the HD at some point as well, however this is a low priority at the moment.
I will eventually build an external 2496 dac using the crystal CS8416 spdif receiver and the bb pcm1798 dac. Plan is to use this with sample rate conversion to 96K for conventional pcm file playback and use the ultralink primarily for HDCD playback.
Once I get the AV/S installed I will provide further updates of progress if any...
Kevin
Thanks for the links guys, still trying to go through all the information...
Kevin- It would be great if you could go into some more detail about your spdif transformer and your coilcraft cm choke, if possible. It is interesting to see serious engineering applied to PC based audio, which I believe to have much more potential then many people would like to admit, even on this site. And I agree with what you said earlier about the PC capable of being as good as a high-end transport. I really do not understand why high-end designers are not using memory-caching mechanisms to combat jitter... And let's face it, no high-end, overbuilt, 80 lb transport (as beautiful as they are) can do anything for a gigantic CD collection if you expect to access the music with speed and precision that current technology alows. Library management is a feature that can no longer be ignored by high-end components.
Video seems to be just a little bit different, i think. First, if you are watching something, you usually do not need to change the media every 5 minutes as you would with music. At the same time, the existence of some very good DVD carousels that provide on-screen library management makes the issue easier to deal with... But with hard drive space hitting such a low price, there is no reason not to add video to the mix as wel.
Kevin- It would be great if you could go into some more detail about your spdif transformer and your coilcraft cm choke, if possible. It is interesting to see serious engineering applied to PC based audio, which I believe to have much more potential then many people would like to admit, even on this site. And I agree with what you said earlier about the PC capable of being as good as a high-end transport. I really do not understand why high-end designers are not using memory-caching mechanisms to combat jitter... And let's face it, no high-end, overbuilt, 80 lb transport (as beautiful as they are) can do anything for a gigantic CD collection if you expect to access the music with speed and precision that current technology alows. Library management is a feature that can no longer be ignored by high-end components.
Video seems to be just a little bit different, i think. First, if you are watching something, you usually do not need to change the media every 5 minutes as you would with music. At the same time, the existence of some very good DVD carousels that provide on-screen library management makes the issue easier to deal with... But with hard drive space hitting such a low price, there is no reason not to add video to the mix as wel.
I will dig up the information on the coilcraft cm choke and the spdif transformer (which came from Digikey) and post it here when I get a moment. I am not sure it is doing anything demonstrably audible, but it does break the ground loop that would otherwise exist between the server and the hifi system.
The highfidelio is available here now, but I can't find information on the importer on the hermstedt website, nor can I find it on google.
I deleted the email with the information as I had already started to build my server by the time they responded.
I am planning to use the server to record tv programs for later viewing and to infrequently download tv programs that I missed and that are now commonly available on p2p networks.
Kevin
The highfidelio is available here now, but I can't find information on the importer on the hermstedt website, nor can I find it on google.
I deleted the email with the information as I had already started to build my server by the time they responded.
I am planning to use the server to record tv programs for later viewing and to infrequently download tv programs that I missed and that are now commonly available on p2p networks.
Kevin
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