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You are reading the older HTML site Positive Feedback ISSUE 41january/february 2009
Ten Questions about Computer Audio with Kent Poon of Design w Sound
Computer Audio has become the new rage in audio and for good reason: one has an easy and instant access to all their music as well the ability to search out countless other titles via the internet. The issue is simply where to start, though the answer is quite obvious: get a computer, rip and store the files, and then play them back to some DAC. Of course being audiophiles …err the nuts we are… the questions start to pile up rather quickly. Mac or PC, and then once you got that settled, there is all the minutiae related to just setting-up that computer’s OS and configuration. Then comes how best to rip and how best to save the files, and then to where? Okay, so now that I have my files, how best to play them back and how best to get the files out of the computer and to what DAC? Yadda, yadda, yadda… each question leads to further questions to clarify the previous that then lead to other questions that suggests another question and …a downward spiral down into the rabbit hole we go. So I went to the 2009 CES and found not only a wealth of information, but a wealth of confusion or at the very least, a wealth of disagreement among those that are either in the recording/software side, the hardware-side, and/or the "expert" sides of computer audio. Now CES is not the best place to get all the answers… time is an issue as is finding all the people to ask, so I came up with 10 ‘key" questions (these are my 10, you may have others or perhaps might not find these of any benefit to you, but I chose them because they are of interest to me and besides they reflect the most common or important areas that seem to pop-up whenever one talks about computer-based audio, so go pound silicon if they don’t work for you.) and emailed them to 12 people in the industry to answer. Their responses are here...
1. Let's start with interfaces; the obvious choices are USB, Firewire, Optical, and S/PDIF. What is your opinion on any of these interfaces? What if any, are the advantages or disadvantages of one over the others in terms of resolution, jitter, etc.? These are all digital interfaces. From a technical perspective, they should perform the same since they carry the exactly same binary digital data. From an audiophile jitter perspective Toslink/Optical is worse than AES/S/PDIF because of the electric to optical conversion. USB and Firewire are mostly computer interfaces. Firewire has been used in professional audio and video industry a very long time for obvious reasons. Although I don't deny USB can also work as good for stereo 24/96 or even 24/192 if you know the technique, since firewire can easily work for 24 channels at 24/192, well that is clearly my choice. 2. With regards to software there are also strong opinions as to some being vastly superior (or for that matter, inferior) to others; people clearly hear differences in how files are being played back and therefore prefer one over the others. There is also a growing opinion that Pro software is the only way to go and that using iTunes, WMP, MAX, or other free software playback programs (FooBar, JRiver, MAX, etc.) is not the way to go. That is, these are sonically and musically inferior to the Pro software because the Pro software (say for example Amarra, Izotpe, etc.) is simply "better" at playing back music files. What is your opinion on what is going on here? That is, why would any of these programs be superior—or for that matter, inferior—to another with respect to say a .wav file in any resolution: 16/44.1, 24/96, or 24/192? Is it a matter of timing and jitter? Issues with the operating software and processing? The fact that some software runs "cleaner" than others—that there is nothing running in the background to muck things up? Or as some suggest that the "math" is simply better in some software than in others? Computer Audio is binary data. For a digital output device, you can verify if the output data is exactly same as the one stored on the computer (the original) by looping back the digital signal and recording on the computer. We did this test and wrote an article on my blog. I am from professional mastering world where we have all the professional audio workstations and software. We can test if the output of all digital devices is transparent to the input. Now we are talking WITHOUT any processing (NO EQ volume, pan etc). If the software involves processing, that's another story. If the software processes the data, it will not be a bit transparent output and different software algorithms can create quite big differences in sound. That's why mastering engineers buy the very expansive Weiss EQ, but do not use iTunes' built in EQ. 3. Let's move on to ripping. As with the above, there are proponents that claim only certain software, and optical drives for that matter, can "accurately" rip a CD. That they can clearly hear differences between rips via different means; even though the rips are bit for bit perfect. Any thoughts on what is going on here? Is there an advantage to using specific ripping software or drives over another? Say iTunes, WMP, Max or whatever when compared to say EAC? We had this test in our article too. From our test, the iTunes rip is as good as EAC/Plextor rips on a disc in good condition. It is not a big deal in ripping with today's computer resources. However an EAC or Plextor rip is only superior because it re-reads the data on a scratched disc and will tell you what's going wrong during the whole process. If the rip is bit for bit perfect, then you will not able to tell any difference because there is none. iTunes has a shuffle function. You can create an album playlist with all bit perfect, but different ripping method files. Work with a friend and play them in shuffle mode to see if you really can detect which is which. 4. File formats. Any reason why a .wav, AIFF, or FLAC file is better than say Apple Lossless? Again people suggest a strong preference for one over the others, so something must be going on here? They all should output (decode) a bit transparent file. However, I always prefer AIFF or .wav simply because these two are industry standard audio files that are supported, not only with a computer in cross platform, but also in digital audio player. Plus they are easy to process if need be. 5. There is also a movement towards Pro DACs. Naturally there are DACs of varying quality and performance, but is there any reason why a PRO DAC would be better than a DAC made by a manufacturer from the audio community? Say ones of comparable quality and build? The professional DAC users are professional engineers. They make their living by recording music. Their preferences on music quality maybe closer to the source than a normal audiophile who does not know what the original music should 'actually' sound like. I guess this gives the professional DAC an advantage, but this is really based on individual case. 6. Along those same lines, what makes one DAC a better choice for computer-based audio than another? Jitter reduction, chip sets, power supply, etc? I look at a good DAC as a complete design. Jitter reduction must be good. Digital interface and analogue interfaces also need to be good. This includes the digital input de-jittering and analogue output driver, and the clocking path, power supply, and blocking interferences of RF and EMI. All these details are more than just a look at what chipset one DAC uses versus another. 7. What do you see as being the most important factor in getting the best sound in computer-based audio? That is what should the consumer address with the greatest concern when setting up a computer-based audio system? Don't try to use money as measure of sound quality. For example, saying that a Mac Book pro can never sound as good as the $10,000 CD transport because of all the audiophile terms regarding their differences. This is a gap between the traditional audiophile and the new generation of audiophiles. The biggest concern in computer-based audio is the DAC. A good DAC will guide you through. 8. Along with that, what do you see as being the most important factor in NOT getting the best sound in computer-based audio? That is, what can have the greatest potential to adversely affect the sound in computer-based audio? I think it is software processing algorithms. Without any technical measurements or a professional testing method, it is not easy to know the quality of those processing algorithms; especially if they are free and claim they can do many good things; such as up-sampling, level changes, soundstage enhancers etc. From a professional mastering background, we are willing to pay a high cost for any audio processing algorithms for good reasons. I suggest the audiophile sends bit transparent output data without any modification to an external DAC of the good quality for the best result. 9. Some suggest that they computer must be audio dedicated. That is it must be "built" or configured for the specific purpose of only playing music and that any and all non-audio related programs and such must be eliminated. Your feelings on this? Is it important or not, and why so? Most modern computers are well above the requirements to playback any high resolution high sampling file; especially on (stereo) 2 channels. The concern should again be put on the DAC. That is the center location where the de-jittering, decoding, and the analogue interface to your audio system is most important. 10. Where do you see the greatest impact to come in computer-based audio for the future? It will definitely be in the future. We can see the path in the success of today's MP3 online market. When the bandwidth is high enough, there are always people who demand more in terms of quality. For example we offer two full length songs free of download charges from our server. These two songs are a full 24/192 kHz in terms of resolution. We welcome everyone to try them. Kent Poon is widely regarded as one of the top Asia audiophile producers and engineers. Kent is currently the consultant of Weiss Engineering from Switzerland, for the production of products including digital equalizer and processors, AD/DA and loudspeaker designs. He was also a technical consultant for one of the largest Asia consumer audio distributors, Radar Audio Company from 2003 to 2007. In the year of 1997, Kent became a full member of Audio Engineering Society (AES) full member. He is one of the youngest full AES members Use the links below to read other responses to these questions Larry Moore and Eric Hider of Ultra Fi Audio Designs Andreas Koch of Playback Designs Steve Nugent of Empirical Audio Gordon Rankin of Wavelength Audio Jon Reichbach of Sonic Studio/Amarra Vinnie Rossi of Red Wine Audio John Stronczer of Bel Canto Designs Daniel Weiss of Weiss Digital Audio Vincent Sanders and John Hughes of VRS Audio Solutions Charles Hansen of Ayre Acoustics Pete Davey of Positive Feedback Online
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