Dynaudio C-1 speaker with a 6.7-inch woofer and 1.1-inch tweeter
(Credit: Steve Guttenberg)Listen, if you're buying speakers, the best thing to do is listen to them. If you can't, you'll learn a lot perusing specifications.
Online shoppers need the most info, but even brick-and-mortar buyers can predict quite a lot about a prospective speaker's performance and system compatibility by looking at the numbers. Tech talk gets you woozy? No problem, the main points of interest would be the dimensions of the speaker and how much the thing weighs.
Hint: bigger and heavier speakers almost always sound better than small, lightweight ones.
So far, so good, but woofer size also provides clues about how much bass a speaker will produce. Bigger woofers make more bass than smaller ones, but the cabinet's size is almost as important a factor as woofer size in determining bass quality/quantity. Multiple woofers may look impressive, but they're less reliable predictors of bass oomph; we've tested lots of skinny speakers with two, three, four, or more drivers that didn't make much bass. The cabinets were too damned small, four 3-inch woofers don't make as much bass as one 6-inch woofer in a larger box.
You might hope the frequency response specification, "38 Hertz -- 22,000 Hertz," would predict how much bass the speaker would make. The first part of that spec, "38 Hertz" refers to the bass output--the lower the number--the deeper the bass. Ah, but since there wasn't any reference to the tolerance of the spec, it's just about useless. Some manufacturers include a "+/-" after the frequency response number, something like 38 Hertz - 22,000 Hertz +/- 3 dB, and that helps a bit. Any speaker that reaches 50 Hz or lower can be considered "full range" and doesn't necessarily need to be partnered with a subwoofer--for music. Multichannel (5.1, 6.1, 7.1) home Theater applications almost always require subwoofers.
I have less to say about tweeters, other than to recommend buying speakers with tweeters; a fair number of pricey "sound bar" speakers are tweeterless. That's not to say they will sound bad, just not as detailed and clear as speakers with decent tweeters.
... Read moreSpeaker impedance is a confusing subject and based on the letters we get here at CNET (see below), I thought I should try shed a little light on the subject. This letter sums up the typical quandary:
"I have a bit of a dilemma that I hope you can help me solve. I have an entry level Yamaha HTIB system that I purchased a few years back and I would like to upgrade it with better speakers. I've done a lot of research and found that owning a 6 ohm receiver limits the selection of brands that I could look at in store or online."
Rotel's 100 watt RSX-1067 A/V receiver can drive any speaker I know.
(Credit: Rotel)I'm all for the speaker upgrade, but he went off track with the concern about his "6 ohm" receiver. The writer mistakenly thinks he's limited to buying 6 ohm rated speakers. Wrong! Any 8-ohm rated speakers would work just as well, and since the vast majority of speakers are 8 ohm rated, his choice of speakers is wide open.
Back to the question at hand: speaker impedance. It's never a fixed number, a 6 ohm speaker may be, on average 6 ohms, but its actual impedance varies with the frequency the speaker is reproducing at any given instant. For example, it may be 4 ohms at 50 Hertz, shooting up to 21 ohms at 100 Hz, dropping back to 7 ohms at 1,000 Hz, and up again to 9 ohms at 10,000 Hz. So in other words, it's impossible to "match" a speaker to a receiver. Impedance is a moving target.
The real world impedance concern comes when using 4 ohm speakers with low power A/V receivers, but even then ONLY when the buyer expects to play the system at high volume. You see, low impedance, 4 ohm or less rated speakers, demand more power than 8 ohm speakers when playing LOUDLY, and that's when the receiver's power might come up short. In a typical "mismatch" scenario the receiver's protection circuit would trip, and shut the receiver off.
Which bring us to the hard cold fact that not all 100 watt receivers are not even close to being equally powerful, but I covered that in my "What's up with watts" blog from a few weeks ago.
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