September 2009

Audiolics Anonymous Chapter 119
Home Theater Computers
Article By Dr. Bill Gaw

  Welcome to another addition of my tome for the insatiable audiophile. As its summer and new equipment to review is few and far between, and since there have been several advances in the field, I thought I'd go back to discussing my love affair with the use of computers as a home audio-video system. My previous thoughts on the subject can be found at:

AA Chapter 29

AA Chapter 36

AA Chapter 101

AA Chapter 105

AA Chapter 106

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This is a discussion of PC's, not MACS. I have never used a MAC, although they are supposed to be easier on the brain, and originally had several advantages for audio reproduction over the PC that made them popular in recording studios. On the other hand the two warring types are coming closer and closer with the MAC now using Intel processors, and the PC's operating system is almost mimicking the MAC's.

It is interesting that the audiophile world is finally catching up on the subject, as there have been several articles recently in both Stereophile and The Absolute Sound, both from a home-built and store-bought perspective. But none of the articles have elucidated the advantages of one either building a complete computer from parts specifically for an audiophile system or modifying a store-bought unit for optimal playback.

Instead, most are pushing special server technology which cost umpteen thousand bucks and have poor to “midlin” electronics built for non-audiophiles who want elevator music spread throughout the house. Or they discuss ways to improve the computer-preamp interface for better sound using USB to S/PDIF adapters or jitter reduction clocks. None that I know of have reviewed the Memory Player, a $12 to 20,000 unit that supposedly maximizes CD playback through a computer. But I guarantee that for 1/10^th the price most of you out there can either build from scratch or modify a decent computer that will compare in sound quality and do significantly more.

None of the high end audiophile magazine have discussed how any one of us with some simple knowledge can build a unit that will allow one to store just about every bit of your music and video software on a hard drive, and play it back through your high end system with fidelity approaching the best and most expensive audio systems out there.

Over the past couple of years there have been several advances in the field that have made it far easier for the home experimenter to be able to build a home theater computer that can match the best audiophile units out there and better them by being able to play back both audio and video at super high bit rates. In addition, the same unit can be used to do all of the normal stuff computers are known for.

The first advances have to do with the operating system. Until Microsoft came out with Vista, XP was a real pain in the butt to work with as it was designed primarily for DVD's, using a so-called kernel mixer in the process. Thus all audio was converted to 16/48 before playback unless your program or soundcard had the ability to use ASIO support. The 44.1 to 48 kHz conversion could muck up the sound somewhat unless done with perfect precision, and the ability to play back unadulterated high bit rate material was impossible. In addition, Windows software, in order to function properly, has many processes working in the background which take up memory and CPU processor time and whose information flow through the same lines as the audio signal, thus interfering with the flow of audio information.

This was worked on and corrected by a discussion board member named CICS (he doesn't want his real name spread throughout the web), who designed both an audio maximized computer he called the Memory Player, and built an audio-only operating system (cMp) and playback program ( cPlay). They allow the digits to be stored and read from RAM, thus decreasing jitter to a minimum. In addition, his program turned on only those processes absolutely necessary for the control of the machine, thus freeing up RAM and circuit transport for the audio signal. This was discussed in detail in my previous articles above. The only problem with it was the inability of the ASIOforAll used to overcome the kernel mixer to play anything back except at a 16-bit/44kHz rate, which has subsequently been resolved by the latest update and the use of the Vista operating system.

Then there was the problem of whether to let the computer do the D/A conversion or have an external decoder do the work, and how to get the information to the decoder with the least damage to the signal. The options were to use the motherboard's S/PDIF RCA or optical, USB or FireWire output to an external decoder which could accept one or more of these. Another was to use a high quality semi-pro or pro internal soundcard for either S/PDIF transfer or analog output.

Use of the motherboard's S/PDIF output tended to lead to high jitter rates due to noise from the motherboard's many computer housekeeping functions, and the USB output has been found to be even worse due to the same problem and its poor transmission properties. Several companies have developed external processors at reasonable prices to change the USB to an S/PDIF output, but why bother. FireWire while it has excellent bandwidth and low jitter rates has the problem of having only mediocre D/A converters, such as M-Audio's Firewire 410 unit. Finally even with the best pro sound cards, the bandwidth limitations of S/PDIF decrease its ability to transmit high bit rate signals without adding jitter, thus precluding the computer from being able to do transmission of excellently upsampled audio.

Digital audio and video data transmission between computer and external D/A converter has been significantly improved by the addition of the new  HDMI connector and protocol. This was developed for transmission of HDTV signals using the HDCP anti-piracy protocol and thus can transmit signals into the multi-gigabit range and with low jitter if done properly. Unhappily very few computers come with motherboards with this output and up until now,  only video cards with only the ability to transmit 2 channel audio were available. See below for the newest fix.

So what are the soft and hardware advances over the past couple of years for using the computer to replace many pieces of audio equipment?

1. Receive, decode and playback ATSC video off the air 720P and 1080I television signals and upsample them to 1080P or higher depending on the television tuner and video cards. No need for an ATSC receiver. Cost about $100. For instance the ATI HDTV Wonder Video Card can be had for a little as $50.

2. Play back Blu-Ray or HD-DVD and DVD-A video and audio recordings. No need for a Blu-Ray, HD-DVD or DVD-A player. For about $100 one can purchase a Lite-On Blu-ray playback- DVD Writer.

3. Even better, add the ability to record to Blu-Ray discs up to 50 gigabytes of up to 24/192 audio for storage and playback. No need for DVD or audio recorder. While I am using a two year old LG combo Blu-ray player recorder with HD-DVD playback, this unit is no longer available. Presently there is the LG GGW-H20L that will do Blu-ray record and playback for about $300.

4. Record true DVD-Audio 5.1 track recordings using the Discwelder Bronze program from Minnetonka Audio. Cost about $100.

5. Transmit high bit rate audio to external processor through HDMI. No need for external transport. 6 foot HDMI cord anywhere from $5 to $100 per media, depending on quality. While I haven't seen any tests from high end audio magazines reviewing these cords, several video magazines have found significant differences in their ability to transmit the signals over long distances due to impedance anomalies. Hopefully there'll be some evaluations in the near future as I do believe HDMI will be the standard in the future for high end audio digital transmission.

6. D/A decoding of low to high bit rate recordings with excellent precision. No need for external D/A decoder. There are many free and not so free programs that will do this. My free favorites are FOOBAR2000 and CICS Player. If you also want equalization, surround sound effects, etc., you could go with Media Center 14 for $50, or to play back DVD's and Blu-ray recordings, either WINDVD9 by Corel for about $90 or Arcsoft Total Media Theater for about the same price. Happily a form of the latter comes free with our major product for discussion below.

7. A/D encoding of old analog vinyl or tapes with the ability to clean up ticks, pops, etc if preferred. You'll need a good soundcard and program to sample at audiophile rates, such as the free program Audacity, or MediaCenter 14, mentioned above. Either will record up to 24/96 files with a good soundcard.

8. Receive several thousand web transmitted radio stations from all over the world and upsample them for sound equivalent to standard FM and superior to the HD-FM transmissions available in the US today. No need for an FM receiver. This is where I've been enjoying myself over the past few nights. It's even better than listening to previously never played CDs as it is free, for the most part un-pirated, with an almost unlimited variety of music. Just about every radio station worldwide now streams their music over the web with many also having video associated with it. The quality can vary from very crappy 32 kHz to better than regular FM 320 kHz, using mp3, mp4, wma, or RealAudio encoding-decoding with most supplying the decoders with the music. Even 64 kHz transmissions beat the new HD-FM digital standard for quality. Streamingradioguide.com lists 9500 plus radio stations on the web, breaks them down by type of transmission and actually will direct you to the stream, and open the correct player.

9. Receive several thousand television transmissions from throughout the world. If you know the TV station web site you can usually get directed from there to their stream or you can get a program such as DTV4PC, which will allow you to view several hundred channels for $40 but at a reduced bit rate. Then there is Hulu and BOXEE, two web sites with multiple downloads from several television networks. Even better, wwitv.com/portal.htm streams over 3000 worldwide TV stations for free. Such riches! Who needs cable or DirecTv?

10. Download, play back and upsample low to high bit rate recordings from several companies through the web, such as HDTracks, 2L Recordings, etc. One can store the recordings on the computer hard drive or in a separate server that will allow any other computer in your house, or even while you're on the road, to be able to play them back.

11. Video cards with sufficient power for HDTV with HDCP HDMI output, unavailable two years ago, and expensive last year, have come down significantly in price this year. For instance, the Radeon Saphire HD4350 goes for as little as $40. It has a VGA, DVI and HDMI output with 512 mb of DDR2 memory, and would have gone for more than $200 two years ago without the HDMI port.

12. The cost of storage has dropped off a precipice over the past year. This is great news for audiophiles, as we can now store all of our CD's on one drive without having to use lossy or lossless compression. Lossy compression leads to artifacts and lossy compression makes the computer work harder and therefore can lead to lower fidelity.

One can now buy a 1 TB drive (that's 1 trillion bits or about what our United States Government adds to the deficit in dollars every few days. I remember when Bill Gates said anything more than 20 megabytes is excessive, that's how old I am) for less than $90 and a 4 terabyte server can be bought for less than $500 for backup and storage. One Terabyte should be able to store over 1000 CD quality and 200 to 500 high bit rate recordings. Just remember to backup the backup as hard drives do have a tendency to self-destruct faster than a record going through a paper shredder.

Finally, we come to the topic of today's discussion, the first of hopefully many soundcards and software to bring together all of the above advances for excellent audio reproduction by using the new HDMI 1.3 transmission standard. I am speaking of the

ASUS XONAR 1.3 HDMI Card
So here is the fix mentioned way above for transmission of pristine high bit rate 2 and multi-channel digital signals and the ability to do excellent A/D and D/A en and decoding. At the same time this is the first audiophile grade card to be able to decode or transmit to an external processor the new Dolby True HD and DTS Master Audio codes for Blu-Ray recordings at full bit rate which are starting to come out with superb sounding concert recordings. By full bit rate I mean that up until now, due to copyright constraints all computers would downsample the 24-bit/96kHz recordings to 16-bit/48kHz before transmission to the external devices or doing D/A.

While ASUS hasn't been known in the past for audiophile-grade soundcards, and this card was aimed not at the audiophile community, but for Blu-Ray playback, they have come out with a winner for us for several reasons.

1. This is the first audio card with HDMI 1.3a output. This allows up to 7.1 channel playback at up to 32 bit 192 kHz sampling rate to be transmitted to an external D/A converter with very low jitter compared to S/PDIF, USB or FireWire. With the ability to accept up to a 1080P video signal through its HDMI input from a video card, with the proper software, one has the possibility of superior audio and video reproduction of ATSC television, DVD-A, Blu-ray or HD-DVD, or over the web HD audio and video transmissions all in one box.

2. The mother card has an HDMI input for connection to either the HDMI or DVI output of a video card with included jumpers.

3. There are actually three versions of the card. The standard unit is a single card with HDMI 1.3a, S/PDIF RCA, and left and right channel analog output. A daughter card can be added as the Deluxe version, and has 6 analog RCA outputs for 7.1 analog output using the two cards. Unhappily, the two cards require two PCI-Express slots, even though the analog daughter card only needs it for placement as it receives all of its information and power from the mother card. This precludes use of older motherboards which aren't supplied with this type of slot. The third variation is the HDAV Slim which has the advantage of requiring only one standard PCI slot and is narrow, thus being able to fit into a smaller space.

4. It comes with National Semiconductor LM4562 opamps but unlike other soundcards these can be swapped with other similar opamps for preferred sound coloring, just like rolling tubes.

5. Has Burr Brown PCM 1796 123dB S/N D/A and Cirrus Logic CS5381 120dB S/N A/D converters, and uses an ASUS AV 200 chip to handle up to 24-bit/192kHz for 7.1 channels.

6. Combined with its included XONAR software, the unit will accept anything from 16-bit/44kHz to 32-bit/192kHz digits for up to 8 channels and does excellent upsampling to that maximum value. It will do ambiance synthesis for stereo to up to 7.1 surround, and will transmit up to 8 channels of 32 bit 192 kHz. audio plus video to an external processor for decoding.

7. The card mixes the audio with the inputted video signal and transmits it through the HDMI output to your pre-pro or D/A converter, or will do D/A internal conversion for 2 channel output directly to your amplifiers if you wish.

8. With the addition of the daughter card, for those using an older pre-pro without HDMI input, up to 7.1 channel analog audio may be transmitted to its multi-channel analog inputs, or straight to your amplifiers. Its software can control right to left and front to back volume control, but not individual control of each channel's volume.

9. The kit also includes a free copy of  Total Media Theater from ArcSoft, which can be used to play back any DVD, Blu-ray or CD disk and any audio or video files on your computer with excellent video and audio fidelity. But I do prefer listening to my audio using CIC's  cMp and cPlay programs, mentioned above, which load the files to RAM, giving far lower jitter levels than one can obtain from reading from a CD or hard disk.

Are there any disadvantages of this card. Yes!! One big one for me. It doesn't have the ability to use 88 or 176 kHz sampling rates, direct multiples of the CD 44 kHz frequency. Instead, it upsamples to either 96 or 192 kHz. But I am uncertain whether this does any damage to the signal. I can tell you that my vinyl transcriptions at 88 kHz from my record collection sound just as superb at 192 kHz. as those I transcribed at 96 kHz, an even multiple, using either FOOBAR or the CICS player. The card should be able to do 88 or 172 kHz playback so hopefully ASUS will update its software for those rates.

A minor problem for me but a possible stumbling block for others may be the fact that the analog output is single-ended only. For those requiring balanced outputs, the Juli@ soundcard from esi audio or any of several pro soundcards will do both, using ¼ inch stereo phono jacks from the balanced output and also has 24-bit/192kHz AD and DA converters and thus can input up to 192 kHz through its S/PDIF input for storage purposes.