You are reading the older HTML site
Positive Feedback ISSUE41
Ten Questions about Computer Audio with Vincent Sanders and John Hughes of VRS Audio Solutions
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.?
All interfaces are imperfect, some are better for audio than others.
Toslink has a lot of jitter and frequently suffers from poor hardware implementation—really cheap and substandard parts.
USB is a very convenient interface. It is very easy for the end user, and comes with supported drivers already made for many operating systems. But as an audio transport, it is not very good. USB actually needs to use some of the CPU resources in your computer to operate, and the USB port the DAC is connected to, is always competing for time on the bus with all other USB connections in the system. The additional resources and resource sharing needs of USB can make the audio stream turn on and off (or stutter) as it's routed to the DAC. The buffer in the DAC can compensate for it, but it still causes a number of problems with jitter and timing. You simply won't find a serious professional audio product that uses USB. There are some 'prosumer' products that use it, but none that are used in serious studio environments. There are some designs out now that can compensate somewhat for it's limitations, but FireWire is still better.
FireWire has wider bandwidth and does not need CPU cycles to transfer data, and has a dedicated transfer bus. Because of this, FireWire can transfer audio data in isochronous mode with guaranteed bandwidth. This means that properly implemented it has less jitter, less buffer under and overuns, and less stress on the DAC, which preserves the musical signal with better integrity. FireWire does require that one writes their own drivers, and we also believe this is one reason it has not been adopted by audiophile companies for DACs.
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?
There are major difference in sound quality between audio players. We began to hear this difference five years ago, and began research to find out why, and to see if we could find a product that could do better. We found that it was about the math. Professional editing and playback software uses less math, and the math that they do perform is more accurate than what is being used in consumer media players. Most consumer player softwares were developed by mating a bunch of software modules together. For instance, the volume function is likely from a third party module, as is the sample rate converter, the cross-fade function, the track position function. The audio data passes through each of these modules as it's played (whether it's engaged or not in many cases). Passing the data through is itself a mathematical transform. In pro audio software, there are less of these steps, so the musical data comes through more accurately. Also, in quality pro software the mathematics for each of these transforms is much more accurate—it is calculated to more significant digits and less rounding of results. The combination of inaccurate math magnified by many transforms can audibly affect the musical data.
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 are still investigating this subject, so we don't have any definitive results to give at this time. Exact Audio Copy or EAC does produce better sounding rips than iTunes or Windows Media Player. It's pretty easy to do a listening test to determine for yourself. We have had many listening tests with skilled and unskilled listeners, and more than 80% of the time listeners preferred the EAC rips. There are other ripping engines that sound as good or better than EAC as well, like dbPoweramp Ripper, CDex etc.
The CD/DVD drive used for ripping does make a monumental difference in sound quality and the ability to get a bit perfect rip (Secure). We generally like external USB or Firewire connected drives like Pioneer or Teac for ripping. Getting the drive out of the computer case and using it's own dedicated power supply, does tend to make a difference. Also, the drives used in Mac Books are generally poor for ripping, and does not handle the stress of re-reading sectors that bit perfect ripping requires.
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?
All of the compressed lossless codecs use a uncompress algorithm while the music is playing back. For some reason, the uncompress algorithm can affect the sound, possibly by adding stress to the CPU, using additional resources in the PC etc. The compressed format that impacts the sound the least is FLAC, but still some can hear it in playback.
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 biggest difference is price. Audiophile DACs usually cost much more than a comparable Pro DAC! Pro DACs are made to work in very tough environments with lots of electrical interference, power supply problems etc. So they tend to sound quieter, with less line noise and more perceived signal to noise ratio. They tend to be very neutral and transparent as well. However, pro DACs tend to require more extensive setup than their consumer counterparts. Some audiophile DACs really start out as Pro DACs, they use the same parts, same drivers etc. The biggest difference is usually the case, the power supply, and the output devices. These can influence the sound, and can be tuned to the designers 'house sound'.
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?
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?
Ripping and playback software are by far the most important factors at getting the best sonic quality from a computer based audio systems.
I have a new analogy for the importance of playback software - it's similar to the cartridge in a vinyl playback system. I think we've all been using the equivalent of $40 Grado cartridges for playback—iTunes or Windows Media Player. While audiophiles have been assembling systems with great turntables (PCs) and phono preamps (DACs) we have been hampered by that first interface, the cartridge (software player). Professional software playback systems sound like Koestsu and Lyra cartridges. They are expensive, finicky, but the results are easy to discern. Once you spend some time with them, the $40 Grado sounds broken in comparison.
Audiophile quality playback software is in it's infancy, we as a community are just discovering it, and the future will bring many more features, improvements and ease of use to this area.
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?
The problem we have seen with customers and on the forums are those who slap together a computer system out of old or inexpensive parts and expect it to sound better than their $5000 CD player. You need real care and planning to get a good result. When we were building the Revelation PC system, our parts cost was five times what was in the equivalent Dell or HP machine. Also, many customers were using the same machine for accounting, email, etc. and clogging up the operating system with all kinds of small resident programs that compete for resources with your music playback.
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?
If the system uses an internal sound card outputting either analog or digital this is indeed, very important. This is because your audio processing is sharing resources with all the other applications in your system. Also PCs are affected more than Macs on this issue.
When you are using either USB or FireWire for outputting the audio, it becomes less important, as these interfaces abstract the data stream more, so there will be less impact. But if you want the best performance, you will keep your computer dedicated to audio.
However, we do believe that every computer system should be reconfigured & optimized for audio playback. This involves removing parts of the OS that are not needed for regular use, but take up resources or memory. Audio computers should remain stable, reliable and consistent over time. We also tweak many of the OS settings for better stability of the data stream, and to ensure that every audio process gets the highest priority in the system. We also setup automatic maintenance so the computer stays optimized over time.
10. Where do you see the greatest impact to come in computer-based audio for the future?
The concepts that playback software makes a difference and that USB and FireWire interfaces can be improved for better playback are new not just to audiophiles, but also to Pro audio designers. I think we can expect some really big improvements in this over time as more designers include this in their goals.
Now that more and more recording companies coming online offering music downloads in higher-rez formats, we can finally get away from the limitations of CD and 16 bit recordings. While we might be in the forefront of what's happening, we have over 300 tracks of hi-rez music on our systems, and it's great to think that one day soon everybody might have thousands!
The consumer market is finally shifting towards valuing sound quality again after years of MP3 dominating the world. This will have a positive effect on what's available for computer audio as well, both in terms of media, and in technology.
Vincent Sanders is the founder of VRS Audio Solutions and is a retired percussionist and educator. He has played with numerous symphonies, classical ensembles, and jazz groups. Vincent became aware of the sonic potential of computers several years ago and subsequently founded VRS Audio Systems to bring this exciting technology to other music lovers
John Hughes has a background in computer software technology, digital audio, and technical marketing. John brings his 25 year passion for high-end audio and video.
Use the links below to read other responses to these questions