Monday, November 19, 2007

DIY music server

Recently I've been thinking a lot about building my own music server. With my recent purchase of a Hitachi H31000U 1 TB hard drive for the bargain price of $199 , I'm one step closer. This weekend I tried the PS Audio Digital Link III DAC which has a USB digital input. The PS Audio offers the ability to upsample the digital data to 96kHz or 192kHz. When upsampling the USB input to 192 kHz every couple of minutes there was a strange occurrence. There was a temporary drop in volume and a very slight interruption of the music, which lasted fractions of a second. Switching the unit to 96kHz solved this issue but also didn't offer quite the same sound quality.

A shootout between the PS audio and my current DAC, the Theta DSP Pro Basic III ended with the Theta coming out on top. So now the HagUsb from Hagerman Tehnology looks will be how I get my current DAC digital information from my future server project. At between $119 to $139 depending on whether one chooses the SPIDF or the AES/EBU, it seems like a bargain. Add to the affordable price a 30 trial period is it seems like a great opportunity. Of course the ideal solution would be a sound card that would have a digital output, however nearly all of those are toslink which is unacceptable for high end applications.

My current vision for the finished music server would be using a Windows XP based PC using iTunes playing WAV files. Apple lossless probably won't be used because even though the files are smaller and there is a mountain of evidence that they have the exact same data as a WAV file after being uncompressed it is a proprietary. If I change to other programs or buy a server a couple of years from now I don't want to have to re burn my music collection. Foobar2000 as an organizational interface also seems popular some more research into that might be warranted. Many use Exact Audio Copy to import music so some reading on that is also probably in order.
Getting better sound from a computer running Windows XP using iTunes is easier than you think. The following changes in total caused a profound increase in sound quality of the 1/8th inch analog out jack of my lap top. Windows XP Setting changes:

After right clicking on the volume control in the tool bar make sure that the “wave” volume control is at maximum and that the balance is in the middle. Both setting are implemented in the digital domain degrade the sound if used. Volume is reduced by reducing the resolution. 1bit of resolution is lost for every 6db of attenuation applied with a digital volume control. Also make sure that you press the advanced button and un click the “1 mic boost” setting. It raised the noise floor dramatically. Going into the “Sound Effect Manage” via the control pannel and making sure that there isn’t any EQ being done there is also advisable. On the “S/PDIF-Out” tab change the sampling rate from 48KHz to 44.1KHz. The bit conversion done by this setting when it is at the 48KHz setting destroys the sense of space as well as reducing tonality in the bass and destroying micro dynamics.

To stop windows sounds from interrupting the music go to the control panel select “Sound and Audio Devices” then to the “Sounds” tab. Under “Sound schemes select “No Sounds” and press the “Apply” and “Ok” buttons.

Changes in iTunes:

If iTunes is the player that will be used to interface with the music library make sure to turn the “Sound Enhancer” and “Sound Check” features off. “Sound Enhancer” boosts the high frequencies and also exaggerates left/right separation. Thus if we want a true representation of the audio this box should be unchecked. The “Sound Enhancer” does nothing more than add dynamic compression in an attempt to reduce the volume difference between songs when in random mode. It goes without saying that compressing dynamics changes the sound and is therefore inherently less accurate, hence undesirable. To turn these features off go to the “Edit” tab, select “Preferences”, then the “Playback tab and make sure that both the “Sound Enhancer” and “Sound Check” boxes are not checked. Also make sure that the volume on iTunes is set to it’s maximum setting because again this is another digital volume control that reduces volume by reducing resolution.

Thursday, November 08, 2007

Treating music with repect

The debate of digital vs. analog still rages on. I’m pretty much neutral. Either can be very, very good if done well, though they rarely are even done adequately. Instead of worrying about whether something is digital or analog let’s start demanding better quality of both. I’ve been fortunate enough to hear direct dubs to CD off of analog master tapes and they kill what is available to us on commercial CD’s.

I believe that one of the most damaging changes to music that is perpetrated by the record industry is dynamic compression. Dynamic compression is the reduction of the volume difference between the loudest and the softest sounds on a recording. Record companies feel that an album or song that is consistently louder will “punch” through other songs on the radio, thus increasing sales. However, other record companies are doing the same, thus it has become an arms race of sorts. The losers of this arms race aren’t the record companies but us, the music buying public. We are forced to suffer music that is uninteresting and uninvolving to listen to, a relentless assault on our senses. Removing dynamics can destroy the nuances is the tone or volume of a singer’s performance, taking away one of the tools in their arsenal to convey emotion to the listener. This removal of nuance also affects every other musical instrument. For the most part Classical and Jazz haven’t befallen this same fate as they don’t rely on air play for sales.

However, we the consumer are not blameless in all of this. Not only do we buy these flawed recordings, many of us do further damage by knowingly or unknowingly digitally compressing the music when we add them to our portable music players. This compression is a different, but far more insidious manipulation. Instead of reducing detail it is obliterated. Information that is judged to be “inaudible” or “unimportant” is simply disguarded in an effort to save space. In effect, many are saying that they are will to sacrifice quality for an increase in quantity.

Unfortunately, Apple is contributing to this wholesale reduction in quality. The iPod isn’t the problem, it’s a tool that can either be used or misused. However the iTunes store sells music at one of the lowest bit rates possible, setting the bar disappointingly low. The iTunes software is also complicit in the affront to music lovers. Out of the box the setting to the software is optimized to maximize storage space, effectively minimizing sound quality. Changing these settings is fairly straight forward. Go to the “Edit” pull down menu, then select “Preferences” from there go to “Advanced” tab and select the “Importing” tab and select either the “Apple Lossless encoder” or “Wav.” Wav is an exact bit for bit copy of the CD. To reduce the space of the files but without losing sound quality select the “Apple Lossless encoder.” It is purported to reduce the file size by half without a loss in sound quality. In practice the new file is slightly larger than half, but tests have shown that when uncompressed for playback it is in fact bit perfect. The only down side of apple lossless files is that they can only be played by iTunes and iPods.