Date: March 19th, 2003
Article by: Burt Carver (Hardware Reviewer & Newsposter)
Product was donated by: M-Audio
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M-AUDIO REVOLUTION 7.1 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.
M-AUDIO 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.
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.
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
 Bels = log(P2/P1)
where P2/P1 represents the power ratio.
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.