December 15, 2004

Speaker Listening

Quite often, when I take off my audiophile hat and put on that of the impartial-reporter-looking-on-at-a-distance one, I become amazed at the lengths people will go to make sure that they are buying the right equipment. Trekking from store to store, comparing everything to everything else, and trying out innumerable combinations of receivers, turntables, and speakers, the intrepid audio shopper usually picks up a great amount of audio knowledge just by twiddling knobs.

And yet he often gets burned -- particularly with speakers. Speakers are undoubtedly the most difficult components to choose, spec sheets, reputation, and price being much less sure guides than with other types of equipment. Sometimes no amount of careful shopping will yield a really satisfactory purchase -- or so it seems.

On a couple of occasions, friends have told me that they have gone to the length of finding stores where they can compare the speakers they have tentatively chosen with the ones they are about to replace; but on buying the new ones and taking them home, the improvement was much less than in the store. Sometimes there was no improvement at all in spite of the fact that, by all rational criteria, the improvement should have been substantial.

The reasons why this might be so are as plentiful as the occasions on which the problem arises; but there are some pitfalls to look for which, if avoided, should keep the speaker buyer from most problems.

The first thing to realize is that no speaker will ever sound exactly the same way in the store as in your living room. So much of the sound of a speaker is determined by its acoustic environment that you would have to find a shop that exactly duplicated your own room to make a real judgment. One solution to this problem is to talk the dealer into letting you take the speakers home to find out how they'll really sound. This might, however, be a trifle late -- you may have passed by many speakers that would sound great in your home before discovering one that sounded good enough in the store for you to consider it as a purchase. One thing you can do, however, is to make sure you listen to a prospective choice in the same sort of environment as at home -- if you plan to put the speakers in a corner, for example, make sure you listen to any potential choices in a corner.

Also make sure that the amplifier driving the speaker is about the same power as the one that will drive your ultimate choice. If the speaker is very inefficient, it may not like the amplifier at all, particularly at high levels. Or, conversely, if the speaker is very efficient, it might mean that you could save a few bucks and buy a lower-power amp.

Efficiency (or sensitivity) is a very important factor in comparing speakers. Like all mechanical devices, a speaker loses some power in converting electrical energy to mechanical, and the amounts vary widely from speaker to speaker. Thus, for a given amount of power from the amplifier, the sound from the speaker may be deafening or inaudible, or any gradation between. Unless the speakers in a comparison have been equalized as to level, switching the same signal between two with different efficiencies will produce a louder sound from one of them. When this happens, the louder speaker will sound better, even when it isn't. This is just as true when the level difference is small enough to be imperceptible (the louder speaker won't sound louder, just better). Efficiency is not really a feature that determines quality, so an advantage gained this way is not really fair.

The way to guard against being fooled by level problems is to ask questions. Ask the salesman if the levels are equalized. If he doesn't know what you're talking about, then you're in trouble. On the other hand, if he says they are, ask him to show you. To equalize levels in the first place, the dealer will have had to feed white noise (such as interstation noise on an FM tuner), or pink noise from a signal generator, to each speaker, and check its level with a sound-pressure-level meter. If he has done this, he shouldn't have any trouble repeating the process for your benefit.

It's also a good idea to have a peek behind the speakers to make sure that the tweeter and midrange controls, if any, have not been set to one speaker's disadvantage -- a favorite trick. Also be wary of comparing speakers placed against the wall or in a corner with freestanding ones. As we have seen, position can affect the sound -- bass, mainly -- to a great degree.

Keep in mind as well the fact that price is a notoriously bad guide to a speaker's worth. Some of the best speakers are the inexpensive ones, while the market abounds with high-priced dogs. If you hear a speaker you like, don't reject it because it's too cheap.

It's often said that the ultimate test of a speaker is how it sounds, and that is really the best guide. But the sound any speaker produces can be affected in all sorts of ways, either deliberately or unwittingly; so don't believe your ears unless you are sure that the demonstration is a fair one.

...Ian G. Masters
ian@mastersonaudio.com