June 1, 2008

Answering the Questions No One's Asking: Part 2

In Part 1 of "Answering the Questions No One’s Asking" I stated, "As a consumer of high-end audio, you have to ask the right questions." I then promised to identify those questions more specifically in future installments of this column.

Before I begin to tell you what questions I think are most relevant, and certainly before I attempt to answer any of them, I first have to outline the ultimate objective of this exercise. In a word, it’s to get great performance from your audio system. But because performance can have many different meanings in this context, I’ll narrow it down: In high-end audio, the measure of performance is whether or not your system achieves a high level of fidelity, or faithfulness, to the source. Just as a race car’s performance might be measured in part by its speed around the track, audio systems are typically measured by how close they come to achieving the perfect reproduction of recordings in the home.

The fly in the ointment is determining what we have to do to make our systems reach that high level of fidelity. As anyone who has ever assembled a high-end audio system can attest, the goal is not an easy one to accomplish. There are so many initial decisions to be made: Which components should I buy? What type of source component and software should I use? How and where should it all be assembled? In their number and complexity, these questions can seem endless.

But let’s break it down a little further: If you accept my premise that what we’re ultimately after is high performance, as measured by how close we get to pure fidelity to the source, you can begin to see which questions are most relevant and in what order they should be asked.

The first question, as I see it, is the most obvious: What makes the greatest impact on a system’s performance? The answer: the thing that varies most from system to system, which is the room acoustic. There’s no escaping the fact that the sound you actually hear is the acoustic output of your system interacting with the acoustic signature of your room.

Rooms vary in their acoustic signatures to an extraordinary degree. However, the science of small-room acoustics is mature, and by now it’s well known that a room’s dimensions, the materials it was constructed from, the textures of its surfaces, and its furnishings all combine to form the room’s acoustic signature. Rooms are measured in myriad ways and with varying techniques. In my experience, it takes a professional acoustic engineer to fully analyze a given room’s signature. Building my Music Vault with the help of acoustic engineer Terry Montlick taught me that you can’t even begin to describe an audio system’s "intrinsic" sound without factoring in your room’s contribution to that sound. And to do that, you have to know, as precisely as possible, what that contribution actually is.

The acoustical outputs of loudspeakers are also extremely diverse. Peruse the links at the SoundStage! Network’s speakermeasurements.com and you’ll begin to get a sense of just how widely the acoustic properties of loudspeakers range. These measurements are made in the anechoic chamber of Canada’s National Research Council, which means that no room effects are represented in the graphs posted because there were none. You see only a plot of each speaker’s output, free of room reflections. When you combine the anechoic measurements of a speaker with the measurements of the acoustic properties of a specific room, you then face the task of controlling both in such a way that the result is high-fidelity sound. This is a big challenge, and it should be tackled first.

More detailed answers to What makes the greatest impact on a system’s performance? are complex and beyond the scope of this column. However, they’re not beyond the scope of what we cover in the various sections of Ultra Audio. Here’s a quick synopsis of what you should do, in order:

1. Examine and improve your room’s acoustics. The best way to do this is to hire a professional acoustician to measure your room and help you design a passive treatment program to improve its sound. If this is too costly, there are several companies that will examine floor plans and offer packaged treatment options for rooms of any size and shape.
   
   
2. Choose your speakers wisely. It is vitally important to listen to a wide range of loudspeakers before you buy. Educate yourself with as much listening as you can make time to do. But even if you fall in love with a specific model, don’t jump too quickly. Listen some more, particularly to your chosen model’s competition. Also, try to listen to your pick in more than one acoustic environment, to hear how it interacts with different rooms. Last, examine the technical measurements of any speakers you’re considering, paying close attention to any third-party measurements you can find (such as those posted at speakermeasurements.com). Did the speaker’s frequency response measure reasonably smoothly both on and off axis? It should have. Is it generally low in distortion? It needs to be. Determining all of this will require some homework on your part -- you’ll need to understand the technical side of loudspeaker measurements, and how to interpret the figures cited. But it’s worth the effort: you then can judge speakers with your own ears and brain, and not feel you have to accept at face value the claims of manufacturers, salespeople, friends, or even the audio press.
   
   
3. When choosing electronics, consider a component that addresses the sonic problems created by the room. Room correction is a technology whose time has come. I’ll delve into this subject in great detail on July 15 in "The World’s Best Audio System." Be sure to check in.

And that’s only the first question and some of its answers. To be continued . . .

...Jeff Fritz
jeff@ultraaudio.com

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