Sunday, January 25, 2009

A Newbie's Guide to Good Audio

What qualities distinguish a good audio system?

We've all heard it before. One walks into a room with a nice audio system set up in it, and someone always says. “Wow! I’ll bet that can play loud!” This, or something like it, is typical of a newcomer’s reaction to an audiophile’s hi fi system.

Why a system’s loudness capability should be the only measure of excellence isn’t difficult to understand. People install expensive hi fi systems in their cars. Some of the larger audio systems seem capable of shaking the host vehicle apart. The pavement trembles when one passes by. A nightclub’s sound system is in the same league: ear-splitting, gut-wrenching, floor-buckling output. With the exception of classical music, which is rarely ever amplified, the same is true for most live concerts. Any more, the average boom box can break a lease, and TV ads featuring hard-pumping woofer cones say it all. "Loud is good" in most beginner's judgments.

Upon actually sitting down and listening to an audiophile sound system, the newcomer will likely say “Wow!” again, followed this time by “It sounds so clear!”

So what is it that makes a high end sound system high end?

Its about the components, but its also about becoming a better listener. This is what separates the audiophile or enthusiast from the casual listener who is merely interested in having cool gadgets. Below are a few terms used by audio enthusiasts that I think are important to distinguishing high end audio from "low-fi but loud" audio.

Accurate timbre and tone - The musical instruments and vocalists sound like they should. A trumpet sounds like a trumpet, etc. Taken to its extreme, the equipment and system seem to disappear, leaving only the music. It can take an audiophile years to achieve this level of performance in their system.

Low distortion - The signal coming into the components is unchanged (ideally) as it passes through. The real world ideal is that the signal is imperceptibly changed as it passes through each component. We haven't made a 0% distortion component yet, but the industry has reached levels approaching 0. It is said that the human ear can only detect levels near 10% distortion.

Low noise floor - Silence is a big part of accurate music reproduction. The quieter the background, the more subtle details that add realism to the music are allowed to emerge.

Soundstage - Soundstage is created by the output of the loudspeakers. It is basically an illusion created by the speakers being fed slightly different signals to fool our ears into perceiving a sense of space that is different from the actual space the audio system occupies. A good soundstage allows the listener to perceive the size and space of the performance venue in which the recording was made. In lower performance systems the soundstage is often limited to the space between the loudspeakers. From that space sound may extend forward from the speakers, but usually not too far behind the speakers.

Ideally, in a high end audio system, the soundstage will radiate from each loudspeaker in a spherical pattern. In recordings with large soundstages, that illusion of a large recording space will be recreated. It will extend beyond the speakers in all directions. In extreme cases if the system is really well designed and the room is properly treated, the soundstage can envelop the listener and appear to extend beyond the listening room walls themself. Immersing the lisener in the venue in which the musical event was recorded. One will not be able to "connect" the sound emanating from the speakers to what they are hearing. This is the situation where listeners will often say the speakers "disappeared".

Imaging - Imaging is a sub set of the soundstage. Imaging is the appropriate placement of instruments and vocals within the soundstage of the recording. This takes some training on the part of the listener to identify, and comes with time.

Dynamics - Dynamics are the differences between the softest and the loudest musical elements. When listening to a live event, even a non amplified performance will have a wide dynamic range between the loudest and softest elements of the music. This is what gives music "punch" and excitement in many cases. A system that portrays dynamics well will sound live on a good recording, and will reproduce those dynamic passages without distortion.

The recording itself is very important when it comes to conveying the sense of dynamics. Unfortunately most of the popular music today has had most of the dynamic aspects removed by being electronically "compressed" during the mixing process by the recording engineer. They do this so that 1) lesser systems do not distort the sound during loud playback, and 2) so one can hear most of the musical elements in a noisy environment, such as a car traveling on a road.

Below are links to excellent illustrations of the results of these recording techniques.

Transparency - When all of the above come together, you achieve a level of transparency. The Stereophile Glossary defines transparency as "1) A quality of sound reproduction that gives the impression of listening through the system to the original sounds, rather than to a pair of loudspeakers. 2) Freedom from veiling, texturing, or any other quality which tends to obscure the signal. A quality of crystalline clarity."

..."The casual audiophile hears reproduced sound as a whole, and judges its quality according to whether it sounds "good." Many reviewers never reach that stage of perception because---convinced by their measurements that all competing products sound "essentially the same"---they never make the effort to listen critically to reproduced sound. The reason a subjective reviewer hears more than the "objective" reviewer is not that his auditory equipment is superior. It's because he has accepted the premise that identical measurements do not necessarily ensure identical sound, and has trained himself to hear the differences when they exist..." - Stereophile Audio Glossary introduction

Those are some of the basic terms we as audiophiles use to describe the sound we are hearing when we listen to a high end audio system. I am sure there can be even more clarification of terms, and additions of others. I invite everyone to chime in an express what they feel is important for the new audio enthusiast to learn/know.

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