How to buy speakers like a boss: A beginner’s guide to home audio

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Specs: Impedance, sensitivity and other techie bits

At some point in your research and shopping endeavors, you are likely to hear that it is important to match your speakers with your receiver or amplifier. There are two facets to this concept. First, you want to make sure that, from a technical standpoint, your amplifier is capable of driving your speakers effectively and safely. The other side of this consideration is how your receiver or amplifier (for simplicity, we’ll just use “amp” generically from now on) sound together with your speakers. Let’s start with the technical part.


Rotel RA 1570 integrated amplifier

Speakers have an electrical characteristic known as impedance, which is measured in terms of ohms. Think of impedance as the resistance your speakers give to the electrical signal your amp is sending to them. While it may seem like resistance is undesirable, in truth, it is crucially important. The amplifier needs to see some resistance to the power it sends, otherwise it will just keep pumping out power until it burns out. Most popular receivers and amplifiers are perfectly happy driving an 8 Ohm “load.” As it happens, many popular speakers have an 8 ohm rating. You will probably only run into trouble if you attempt to drive a low-impedance speaker (4 ohms or 2 ohms) with an amplifier that just doesn’t have the juice necessary to do so safely. If you find yourself looking at 4 Ohm speakers, know that you will need some serious amplification to drive your speakers to healthy volumes without putting your speakers and amp at risk. If some of the speakers you are looking at are rated at 6 ohms, just know it will take more power to get those speakers to the volume you want. If you have a well-powered amp, you aren’t likely to run into problems unless you drive several 6-ohm speakers at once up to ear-splitting volumes. At that point, your receiver may start “clipping” and you can do damage to your speakers.


Naturally, this brings up the question of how much power your amp (or the amp you may be purchasing) has. You may be under the impression that your amp puts out 100 watts per channel. However, you might be surprised to learn that electronics manufacturers often “cook the books” to make their product’s power ratings look good and, because of that, you may actually be working with less power than you think. Don’t worry, if your amp has always sounded good with 8-ohm speakers in the past, it will continue to do so. Again, it is only if you are considering a low-impedance speaker that you should take a close look at how powerful your amp really is. If you are looking at 8-ohm speakers, whatever amp you are working with is likely to do just fine. Don’t stress about over-powering your speakers either, it is very rare that anyone does damage to speakers because their amp is too powerful. More often than not, people’s ears will give out to excessive volume before their speakers will.

Another measurement you may run into while looking at speaker specs is “sensitivity.” In a nutshell, this refers to how loud a speaker plays per watt. Speakers with a low sensitivity will require more power to get them to loud volumes. The opposite is true for high-sensitivity speakers. Generally speaking, consider a speaker with a sensitivity rating of 80dB to 88dB per watt to be on the lower end of the spectrum and 89dB to 100dB per watt or more toward the top.

There is also a synergistic consideration when pairing speakers with an amplifier related to sound characteristics. You may hear of speakers described as “bright” (an emphasis on treble), “laid back” or “punchy.” Amplifiers, like speakers, will also exhibit certain sound characteristics. You can imagine how a speaker that is described as bright paired with a receiver that is also known to sound bright could team up to produce a particularly bright sound that you might not enjoy (or you might…and that’s cool, too). Yet, when paired with an amp that is known to sound mellow, a bright speaker will be tamed and the resulting sound may be more to your taste. You can imagine the potential combinations from here. This factor can be important both for those purchasing a new amp and those that already have an amp and want to find speakers that will best match it.

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