Date: March 19th, 2003
Article by: Burt Carver (Hardware
Reviewer & Newsposter)
Product was donated by: M-Audio
<---Shop for the M-Audio Revolution 7.1 PC Surround Sound Card
Here
COMPANY PROFILE
M-Audio (formerly Midiman) is a leading provider of digital audio and
MIDI solutions for today’s electronic musicians and audio professionals,
as well as recording enthusiasts and music hobbyists. Highly successful
since its founding in 1988, the Company now has independent offices in
the US, Canada, UK, Germany, France and Japan. M-Audio’s ability to develop
advanced technology into affordable products has led the Company to win
some of the international audio community’s highest praise and awards—including
being named the “industry’s fastest growing company” for the past two
years by Music Trades magazine. The Company recently launched its Consumer
Audio Division, bringing professional-quality audio to the consumer market.
PRODUCT INTRODUCTION
The Revolution 7.1 is an audio card boasting 8 available channels of
output. The card is based on the Envy 24HT sound chip, and boasts some
impressive features.
PRODUCT OVERVIEW
I do not profess to be an audio expert, however I do have some passing
knowledge of audio. Too often people base their audio purchases on what
their neighbour Bubba tells them. "More Watts! More Power!".
Even the slightly-less-than-unwashed masses rely on statistics that are
meaningless to most. THD. SNR. RMS. TMA (Too Many Abbreviations).
In many cases, the sales representative doesn't know much more than your
neighbour Bubba. Before I get too deep into looking at this card, I thought
a quick primer on sound was a good idea to filter through some of the
'marketese voodoo' that plagues the audio market.
Important Stuff:
SNR - Signal to Noise Ratio: The technical definition of this includes
a formula that makes my head spin.
In english? SNR measures the 'noise' introduced by the circuitry of whatever
is dealing with the audio signal. By the time the signal reaches your
ears, there can be several things that increase the noise. The soundcard,
the speaker cable, and finally the speaker can introduce unwanted noise.
A higher SNR number (measured in decibels) is better. Professional studio
recording gear has an SNR of 120DB. A 'poor man' method of testing your
equipment is to disable all inputs on your stereo receiver, and crank
up the audio. Most consumer level receivers have modest SNR ratios, and
as the volume gets higher the speakers will start to hiss, hum, or buzz.
Below is a small table illustrating various SNR readings.
THD - Total Harmonic Distortion: Another technical definition. Begin
head spin.
Little fuzzier on this one. This relates to the amount of 'colour' introduced
by the signal processing equipment. Essentially, this compares the 'source'
sound to the 'output' sound. The amount of variance is expressed as a
%. In this case, lower is better.
Dd - Decibels. Another DRY technical explanation.
The Decibel is a subunit of a larger unit called the bel. As originally
used, the bel represented the power ratio of 10 to 1 between the strength
or intensity i.e., power, of two sounds, and was named after Alexander
Graham Bell. Thus a power ratio of 10:1 = 1 bel, 100:1 = 2 bels, and 1000:1
= 3 bels. It is readily seen that the concept of bels represents a logarithmic
relationship since the logarithm of 100 to the base 10 is 2 (corresponding
to 2 bels), the logarithm of 1000 to the base 10 is 3 (corresponding to
3 bels), etc. The exact relationship is given by the formula
[1] Bels = log(P2/P1)
where P2/P1 represents the power ratio.
HUH?
Anyone familiar with the Richter scale will catch this one quick. Decibels
are a measure of sound. Unfortunately, it is not a linear measure of sound.
110dB is NOT 10% louder than 100dB. Decibels are measured using a logarithmic
scale. Huh again? What this means is that instead of 110dB being 10% louder
than 100dB, it is actually TWICE as loud. An interesting link is located
HERE and goes though
various dB levels.
This review does get interesting. Trust me.
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