6. Speakers
Loudspeakers—what are they? For most of us they are a set of speaker drivers (like a tweeter and a woofer) installed in the front baffle of a speaker cabinet with speaker cable terminals and possibly a bass port. Simple.
Or not.
Speakers come in various shapes, sizes, power handling capabilities, efficiency/sensitivity, frequency response, impedance etc. All these factors (plus a few more) influence how your music will sound once it is played through your speakers. That is the key, as with all other components in the hi-fi system chain. The music should be played through, not by, your speakers (and system).
Hi-fi speakers come in two main sizes: bookshelf (sometimes also referred to as standmount); and floorstanding—the difference being cabinet size and volume. Bookshelves, because of their increased cabinet rigidity due to their smaller cabinet size, tend to colour the sound less than a floorstander, but also have less bass response because of their smaller size. Floorstanders need substantial bracing inside the cabinet to overcome any colouration the cabinet itself will add to the sound. (So if the cabinet sounds hollow when you rap it with your knuckles, walk on.) They are able to produce a wider frequency spectrum and "fuller" sound than bookshelves.
It is incredibly difficult for a loudspeaker to faithfully reproduce the entire range of human hearing. Most speakers reproduce sound from about 40Hz to about 20 kHz depending on their size. Always seek speakers with high-frequency performance as close to 20kHz as possible, and as low an extension on the bass end as is feasible. You might also need to add a subwoofer if you enjoy bass. A good subwoofer will produce from 20Hz up to about 100Hz. Together these speakers will give you nearly the entire audible spectrum.
With power-handling, a higher rating is always better. A speaker might have a minimum requirement for power handling, but will most likely have a maximum allowable amount. A speaker with a 100 watt power handling rating can be safely operated when connected to a 500 watt amplifier. It's not going to explode or anything like that. The truth is that high amplifier power almost never destroys a speaker. In most cases, it is a lack of amplifier power that causes damage. The key is to use your speakers with an amplifier that produces sufficient output to drive the speakers without distortion, or "clipping."
When choosing loudspeakers for your system, the first rule is to listen, listen, listen. Ideally speakers and amplifier are purchased at the same time. This is because of the interactive relationship these two components have. If this isn't possible, then careful attention must be paid to a couple of specifications.
The amplifier must have sufficient power to drive the speakers. Check the efficiency (or sensitivity) of the speakers. This is rated in dB. Less than 89dB efficiency requires more current from the amplifier, thus more wattage. Speakers rated at more than 89dB are efficient, and can be driven quite easily by most amplifiers.
The other specification to keep in mind is the nominal impedance, or the load in ohms. The lower the number of ohms, the more power flows into a speaker. This can pose a difficulty to the amplifier, as the lower resistance means the amplifier must deliver more current to the speaker. Most speakers exhibit loads of 4 ohms to 8 ohms. Some very high quality speakers may present an average 2 ohm load, which means that the amplifier must deliver very high amounts of current to speakers constantly. Not many amplifiers can do such a thing constantly and continue to function correctly. You should seek speakers with impedances in the 4 ohm to 8 ohm ranges, as they are the easiest to drive for most amplifiers.
Lastly: just listen.
Listen to how speakers play music you're familiar with. Is there a tinge of grainy brittleness to the treble, or muddiness in the bass? Is there a lack of midrange or, conversely, too much?
How broad is the soundstage? How deep is it? Are the instruments well defined and separated in the mix? Can you place them? Do vocals come through clearly and articulately?
Your ears will tell you which loudspeakers are right for you.