Speakers for Your Deck
or Patio
At the risk of pushing the season a bit, let's consider the
notion of music in your backyard. Why abandon decent sound just because the weather is
warmer? But beware: setting up an outdoor audio system is just about as challenging as its
under-the-roof counterpart except that all the rules have changed.
The acoustics of open-air hi-fi are radically different
from what we are used to, and the speakers themselves vary widely as to how they perform
in the open air, and as to how they last. How they sound is important, but not necessarily
all that important. For one thing, you're probably not going to do a lot of
critical listening as you barbecue those burgers, so not-too-awful is usually okay in an
outdoor system.
Indoors, reflections of various kinds can radically alter
the spectral balance of a speaker, especially at low frequencies, and so designers try to
anticipate such influences in the inherent balance of their products. Generally, such
boundary effects are minimal outdoors, however, so many speakers tend to sound thin when
played in the open air. In some cases, the low end can be restored by equalization, but
that tends to demand lots of power, and not all speakers can handle it. Better to choose
something that already has full enough bass not to need reflective support.
Many in-wall speakers fall into this category, and they
have the advantage of being quite well protected from the elements when mounted -- if
you can find an appropriate place to install them. Many, but not all, outdoor speakers
have intentionally boosted bass, and these should be considered.
Energy Loudspeakers makes the Tempest that has a switch (below) to "equalize"
the speaker for either indoor or outdoor use.
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Even if a speaker has the proper sort of
balance for outdoor use without equalization, it is likely to be somewhat power-hungry
because it usually needs to play louder than it would inside. That's partly because of
lack of reflections, again, and partly because we tend to sit farther away from the
speakers than we would indoors. One solution is simply to use a big amp, the other is to
choose speakers with high sensitivity. Not all speakers specify this, mind you, so you may
have to ask a few questions to find out whether or not a particular model is suitable.
An alternative to loud loudspeakers is multiple
speakers. In many situations, several speakers playing at low levels can produce a more
pleasing sound than a pair playing at high levels, and your neighbors will much
prefer this sort of setup.
Multiple speakers will obviously require more money, other
things being equal, but technically the chief risk in using more than a pair of speakers
is presenting your amplifier with a low enough impedance to damage it. Even if you are
careful to select a speaker with relatively high nominal impedance -- 8 ohms, say -- you
can't be sure that it doesn't dip to a dangerously low figure at some frequencies. The
only safe way to run multiple speakers outdoors is to amplify them individually. While
this does increase cost, the amplifiers can be low-power models, and thus fairly cheap.
One major enemy of an outdoor speaker is likely to be
moisture, both in the form of rain and humid air. To some extent, the effects of the
former can be minimized by mounting the speakers in sheltered locations, where rain can't
fall directly on them. That's not always possible, however, and even when it is, rain can
still blow about and splash onto a speaker, so care should be taken to check how
water-resistant a particular model is.
Steer clear of models that aren't completely sealed;
moisture can get inside and cause a number of nasty things: rusting components, mold, even
tiny critters. When checking the box, go beyond making sure that it isn't a ported model;
even banana-jack terminals and other small holes can let in moisture.
The drivers themselves should be plastic -- polypropylene
is ideal -- as fiber or paper cones can get soggy and disintegrate. Metal cones and domes
are also virtually weatherproof. Foam surrounds, on the other hand, can eventually admit
moisture, but they are often used nevertheless for reasons of cost. You may choose to ante
up a few extra bucks for speakers with impervious surrounds unless your speakers will be
well out of the rain.
The other major aspect of weather is temperature, but
fortunately even general-purpose speakers can normally work without problems over a wide
range of temperatures. Heat can matter, but for most listeners, making sure the speakers
are located in the shade is the best precaution. If that's impossible, use white speakers
that reflect the heat rather than absorbing it; many outdoor models come in black or
white, but if your choice doesn't, there's no law against painting your speakers.
One potentially damaging effect of sunlight is ultraviolet
radiation. It can quickly turn some material -- foam surrounds, for instance -- to dust,
and cause glues to disintegrate. Keeping the speakers out of direct sunlight is a sensible
precaution, but if that doesn't fit your situation, you can minimize UV effects by picking
a speaker with a grille that blocks the rays. If the grille snaps off, try to see through
it in strong sunlight; if you can (or if you can see the drivers when the grille is in
place), the UV can get through and do its damage.
Paradigm's Stylus speakers are weather resistant, suitable for
indoor and outdoor use.
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However well sealed a speaker might be,
there are a couple of things that have to be on the outside of the enclosure, exposed to
the elements: the connectors. Only one is ideal for outdoor use: heavy-duty binding posts.
If they are gold-plated, even oxidation is no risk.
It's generally inadvisable to place outdoor speakers on the
ground, or your deck, or indeed on any level surface, as that means they will probably end
up sitting in a puddle sooner or later. Wall mounting is safer, and almost all outdoor
speaker makers supply brackets to make this easier. Take a good look at how these attach
to the speakers themselves. Flimsy tabs that fit into recesses on the enclosures might be
less obtrusive than heavy bolts, but they also might result in one of your speakers coming
loose and bopping your Cousin Frieda on the head.
The out-of-doors is basically hostile to audio equipment,
and even the most impervious speakers won't last forever when exposed to nature. It is,
however, possible to prolong a speaker's life by the simple expedient of taking it inside
when it's not being used. To that end, many brackets make quick dismounting relatively
easy, and the few moments it takes to disconnect or reconnect the cables are time well
spent.
...Ian G. Masters
ian@mastersonaudio.com
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