Installing and Setting Up Loudspeakers
By Michael Riggs
and the way they are placed in the room, will have far more effect on
your systems sound than any other component. For that reason,
its important to spend a little time at the beginning making sure
they are set up optimally.
Start by ensuring that there is no basic mismatch between the speakers
and the amplifier or receiver you plan to drive them with. For example,
if you have relatively low-sensitivity speakers but will sometimes want
high playback levels, you will want powerful amplifiers. (Loudspeaker
sensitivity is rated in decibels of sound-pressure level, or dB SPL,
at a distance of 1 meter with an input of 2.83 volts, which is equivalent
to 1 watt into 8 ohms. Modern loudspeakers typically have sensitivities
in the range of about 90 dB SPL/1 watt/1 meter. A low sensitivity rating
would be around 87 dB or less.) Most people, however, will find 50 watts
per channel to be quite satisfactory and 100 watts/channel generous.
Do not be overly concerned about actual power ratings on loudspeakers.
Usually these are meant to give a rough indication of how much power
a speaker can handle without being damaged. In practice, however, so
many variables are involved that it is impossible to come up with a
single number that is valid under all, or even most, circumstances.
A more likely source of trouble is in the realm of impedance. If your
speakers impedances are lower than your amplifier or receiver
is designed to handle comfortably, you may find the latter distorting,
overheating, or shutting down when stressed. Speakers with rated impedances
of 6 ohms or higher will usually work fine with any decent modern amplifier
or receiver (even those that say on the back to use only speakers rated
8 ohms or greater). But if you have 4-ohm speakers, make sure your amplifier
or receiver has high current capability and is rated to handle 4-ohm
loads. A 4-ohm power specification is a good indication of this.
Terminals and Cables
Your receiver or amplifier will have at least one or two sets of relatively
large terminals that are designed to accept speaker wire. Wire clips
accept bare wire or pin connectors. Better models usually have binding
posts for at least the front left and right speakers. Binding posts
normally accept bare wire, pins, banana plugs, and spade lugs (which
resemble hooks), though some omit support for one or the other of the
last two. Bare wire and spade lugs provide the securest connections,
because they have the large contact areas and can be clamped down tightly.
Snugly fitted banana plugs are almost as secure, however, and much more
convenient when you need to disconnect and reconnect for any reason.
(If the binding posts for the positive and negative sides of each speaker
connection are spaced _ inch apart, you can use double banana plugs,
which make life even easier.) Wire clips make decent connections but
are neither as convenient as bananas nor as secure as bare wire or spade
lugs. Although there is a thriving market in premium speaker cable,
there is no real technical or sonic imperative for using wire of unusual
construction or exorbitant price. Ordinary stranded copper wire (lamp
or zip cord) is perfectly satisfactory provided that it is not too skinny.
(The thicker the wirewhich corresponds to lower gauge numberthe
less its resistance to the passage of electricity.) The thinnest wire
you should consider using is 18-gauge, but since 16-gauge costs only
slightly more and is scarcely less flexible, we recommend it for everyday
use. For long runs (more than 15 or 20 feet), especially to low-impedance
speakers, you might consider moving up to thicker 14- or even 12-gauge
cable. If you do, just make sure whatever you buy is reasonably flexible;
such thick cable can be too stiff to handle easily if it isnt
braided to maximize flexibility. And if you intend to run any wire through
walls, make sure it meets local electrical codes for in-wall electrical
cabling. If you are making bare-wire connections or adding your own
terminations (banana plugs, spade lugs, etc.), go to the hardware store
and invest a few bucks in a decent wire cutter/stripper. It will resemble
a pair of pliers with notches for cables of varying thickness. This
will save a lot of aggravation.
When measuring your listening space for speaker cable, keep in mind
that you're interested not in just one distance (amp to speaker), but
several. That includes the distance from the amp to the floor, the distance
from the point below the amp to the wall perimeter, the distance along
the wall, the distance out from the wall to the speaker's base, and
the distance up from the floor to the speaker. Add at least a foot to
allow slack. If you are using bare wire, you might even add another
six inches to allow for mistakes when stripping the ends. When you're
done stripping, twist the strands together to form a compact hunk of
copper that can be slotted into or wrapped around a speaker terminal.
And before you connect anything, make sure your receiver or amplifier
is turned off. If your amp is powerful and has just been on, unplug
it for a few minutes before touching speaker connections, to give its
internal power supply time to drain.
Red and Black
Speaker installation always involves matching connections. In other
words, using standard color coding as an example, red always goes to
red and black always goes to black. The red terminals on your speakers
and amp are the positive (+), or hot, connection. The black terminals
are the negative () or ground connection. This helpful color coding
may continue on your cable if you have professionally terminated premium
stuff. If you're using generic cord, with two leads grafted together,
you can figure out which end goes to which by looking for a ridge or
colored stripe on one side. Just adopt a convention, such as always
connecting the marked conductor to the positive (+) terminals at both
the amplifier and the speakers. Consistency is the key. If you wind
up with some speakers connected one way and others in reverse, imaging
and bass output will suffer, giving the sound a somewhat weak, disembodied
character. Even more important: Make sure that no wire strands touch
both the red and black terminals at either end of the connection. That
will create a short circuit, which could impair performance, cause the
amplifier or receiver to shut down, or even damage the amp or receiver.
Active (meaning self-powered or powered) subwoofers are best hooked
up using an RCA-jack subwoofer output from your preamp or receiver rather
than a speaker output.
Sound is so heavily influenced by acoustics that it is best to think
of the room as a component in the system. Will any set of speakers sound
good in your room? Try the slap-echo test. Clap your hands around a
room, first in the middle then near a wall. How much echo is there?
A lot of echo will muddy the presentation by smothering direct sound
with reflected sound. You can usually tame this sort of problem by adding
carpeting, upholstery, or wall hangings, such as tapestries or curtains.
The least expensive and often most effective acoustic treatment is proper
placement of both speakers and listener. Sound varies depending on where
it is produced in relation to room boundaries (walls, floor, and ceiling).
Where you place speakers in the room is as important as what speakers
you buy. Front speakers usually should have their tweetersthe
small drivers delivering the highest soundsapproximately at seated
ear level, which in practice is similar to eye level. That is why they
are usually mounted near the top of the speaker enclosure. Where the
speakers should be placed in relation to walls will depend on their
design. Check user manuals for any specific tips the manufacturer might
provide. Except for subwoofers (see below), you will usually want to
avoid placing speakers in corners, unless they are specifically designed
for such positioning. Some speakers will sound bass-heavy when pushed
back against a wall, whereas others will should bass-shy if moved out
into the room. Experiment to see what works best for yours. Center-channel
speakers in surround setups should be placed directly above or below
the TV screen. Try to keep them as close as you can to the same height
as the front left and right speakers. Remember that any speaker placed
within a foot or so of a direct-view television set should be magnetically
shielded, to prevent picture interference. Surround-channel speakers
usually work best when placed somewhat above seated ear level (but not
right up against the ceiling) and to the sides of the listening position.
Dipole surround speakers should be directly to the sides of the listening
area. Placement of front-radiating and bipole surrounds is more flexible,
and you may prefer moving them slightly back of where you would put
dipoles. If side-wall placement is impractical, you may find somewhat
unconventional orientations rewarding. For example, if your listening
position is right up against the back wall of the room, you might try
putting a pair of speakers on that wall but facing up so that their
output bounces off the ceiling. Whatever you do, avoid aiming the surround
speakers at the listening area. You want them to produce a diffuse,
enveloping sound field. Its good for their sound to bounce around
a bit before it reaches your ears. A true subwoofermeaning one
that operates only below 100 Hz or sowill be very hard to locate
by ear. (Note, however, that a poorly designed subwoofer may generate
higher-frequency distortion products or have inadequate crossovers that
"leak" information above 100 Hz.) This nonlocalizable character
of deep bass is helpful, because it means you can route low frequencies
from any channel to a subwoofer anywhere in the room and still have
it sound like its coming from where it ought to. So you can place the
subwoofer for the smoothest, deepest bass response and the other speakers
in the system for best imaging. For the subwoofer, the ideal location
almost always is a corner away from any open windows or doors. You may
want to experiment with placement, but use a corner as the starting
point and see how close you can get to perfection just by adjusting
the subwoofers level and crossover settings. But what about not-quite-subwoofers?
There are quite a few speaker systems on the market that use very small
satellite speakers coupled with a common bass module that handles all
the low frequencies. In these systems, the "subwoofer" seldom
cuts off below 120 Hz and may operate as high as 200 Hz. Depending on
the exact design and how fussy you are, you may or may not be able to
tuck the bass module out of the way in a corner. If you find male voices
and such straying oddly, try putting the bass module against the front
wall between the left and right front satellites. One more thing to
watch out for: If your speakers have openingsvents or portsin
their backs, make sure you dont smash them right up against a
wall. The vents need at least a few inches of space to breathe.
Position your listening chair in the sweet spot, which should be an
equal distance from the front left and right speakers and (in a surround
system) directly in front of the center speaker. If possible, your seat
should be at least a couple of feet from the wall behind you. In a stereo
pair, most listeners prefer that the distance between the listener and
each speaker match that between the speakers (an equilateral triangle).
This provides good stereo separation, though it may leave the space
between the speakersknown as the soundstageless than solidly
defined. The imaging of instruments or voices within the soundstage
will come into stronger focus if the speakers are closer together (or
the listener farther away). Your distance from the left and right speakers
should be no greater than twice that between the speakers themselves.
Start with the left and right speaker cabinets toed in so that they
face the listening position. This will provide the most direct blast
of sound. If the resulting sound is harsh or too bright, or if you want
more than one critical listener to enjoy the music, start angling the
speakers more and more toward facing straight out, until you find the
optimum mix of focused and dispersed sound. You can manipulate bass
by placing speakers nearer a wall (or walls). Try to get a smooth, natural
sound. More bass is not always better!