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Upgrading OPAMPS on the X-Mystique

 

Gimmick or Necessity?

 

by Josh Walrath

 

            Some weeks ago I looked at the BlueGears X-Mystique soundcard which is the first add-in board that is able to encode a Dolby Digital 5.1 signal.  Since that time things have changed a bit.  HiTec Digital Audio (HDA) has now changed its name to Auzentech, and BlueGears is no longer the primary distributor for these products in North America.  Instead, that task falls to Auzentech, Inc., which is the local distributing arm of the parent company in South Korea.

            The X-Mystique’s primary claim to fame is that it is the first add-in soundcard that can encode a Dolby Digital 5.1 signal.  Previously only the NVIDIA SoundStorm and some Intel High Definition audio products were able to do this, but the SoundStorm was killed off by licensing fees and low OEM demand, while the Intel solution requires CPU cycles to encode the stream and there are widespread reports of terrible latency in such a solution.  So with the choices being an Athlon XP enabled nForce 2 board or a laggy Intel DD 5.1 solution, users who demanded DD 5.1 encoding were left in the cold until the release of the X-Mystique.

            One of the bullet points on the X-Mystique is that it has upgradeable OPAMPS.  While many users think that this is a nifty idea, most have absolutely no idea what this really means.  When I first had the X-Mystique, I also had no idea what the real benefits of upgrading the OPAMPS would be.  After reviewing the X-Mystique I thought I would take a look into what exactly upgrading these OPAMPS would entail, and what kind of benefits I would actually receive.  With that being said, let us take a quick look at what computer audio is comprised of. 

The Basics (and I mean the very basics)

            While I do enjoy audio a great deal, I am not an expert on the subject.  What I give here is a very basic overview of PC audio.

            We live in an analog world.  Sound continually washes over us in waves, and the very vibrations our ears detect continually sweep over us.  From the vibrations of vocal chords to produce voice, to the pounding waves brought on by drums, sound continually streams towards us.  In the digital world things are divided into bits and bytes, packets and files.  As such things are much more “blocky” in the digital world. 

To visualize this consider a wave form.  If we take a pencil and draw a wave we see that the line smoothly travels from one point to another.  In the digital world this is not possible.  To digitally “render” such a wave form, it is impossible to gather the infinite points between any two portions of the waveform.  To get around such an imposibility, information is taken from points along that waveform.  While this may accurately record such a waveform, a lot of information is lost during this process.  To more accurately represent this analog waveform, more sample points must be taken.

In this rather simplistic drawing we see that while the top "analog" waveform is smooth while the "digital" representation shows that while it follows the general path of the waveform, relying on finite slices of information gives an artificial flavor. 

PC audio has gone through several transitions in its lifetime, from 8 bit, to 16 bit, and now to 24 bit.  Sample rates have also improved dramatically over time.  Currently the top end products support 24 bit audio with a 192 kHz sample rate.  This allows a very large and accurate representation of an analog signal, but it is still not perfect.  There is currently work being done on 32 bit audio with higher sampling rates, but we have to ask ourselves eventually how good is good enough?  At what point can we say definitively that we can’t hear the difference between a live analog sound vs. a digitally represented one?  Conventional wisdom right now says that 99 out of 100 people will not be able to identify a clean analog recording vs. a 24 bit/196 KHz recording.  And in fact most of those 99 people will probably prefer the digital recording because it will not feature any of the analog recording and playback limitations (crackling and hiss from either tape or vinyl).  But for better or for worse, those 1 out of 100 listeners are very vocal about the limitations of 24 bit digital audio.

             In PC audio sound goes through several stages before it reaches the listeners’ ears.  First there is the source material.  This could be an MP3, a CD audio or PC wave file, or DVD Audio.  Each of these formats has their own advantages and disadvantages.  An MP3 file’s main advantage is decent overall sound quality vs. file sizes, while a DVD Audio file has very good sound quality but large file sizes.  Standard CD audio is recorded in 16 bit/44.1 KHz, but this is essentially an uncompressed format and a lot of engineering and clever tricks are done with the recording to give very good results.  DVD Audio on the other hand can support up to a 24 bit/192 kHz format, but often falls back on 24 bit/96kHz for multi-channel playback and space concerns.  That means that at maximum there are 192,000 samples per second taken, while CD audio has a max sampling rate of 44,100 samples per second.

 

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