Yes. But not for the reason you think.
Integrators install backboxes for three reasons — to reduce
sound transmission into adjacent rooms, to ‘claim the space’ in the wall or
ceiling, and to protect the speaker from debris.
As a rule, backboxes do not improve the acoustic performance
of good speaker systems. Inferior speakers may benefit from the ‘stiffening’
backboxes provide, but we’re not talking about inferior speakers here.
Architectural speakers need a good amount of open air space
behind the drivers. Most architectural speakers use an Infinite Baffle design,
with the back of the speaker playing into the wall. Infinite Baffle designs
work best when there’s an infinite (you saw that coming) amount of unimpeded
air space behind the speaker. When the air space is too small, the springiness
of the air stiffens, which constrains the movement of the bass unit. Reduced
airspace reduces driver movement, which reduces bass extension and overall
To test this, simply put an architectural speaker into a
wall that’s stuffed to the brim with insulation. You’ll hear no bass and no
impact. We call this overdamping, or choking.
The more bass a speaker is capable of producing, the more
air it needs behind the drivers. That’s just physics. But most manufacturers
(us included) size our backboxes so they fit between and are no deeper than a
2x4 stud. That means a backbox would have to be at least two feet tall to give
enough breathing room to achieve bass to 60 Hz.
If a speaker is capable of reaching down past 60 Hz, but
it’s put into a smallish box, the speaker will lose a good deal of bass
Most enclosed architectural speakers suffer from limited bass
specifically because of this issue.
Reduce sound transmission
Well constructed backboxes — with plenty of absorptive
material — reduce sound traveling into adjoining rooms at certain frequencies.
High frequencies above 500 Hz are nicely contained within the box. But low bass
notes are not, and while attenuated, escape the confines of the box,
regardless of construction.
Think of it this way: when you’re at a stoplight and a car
pulls up next to you with loud, heavy bass music playing, you can easily hear
the music. And this is music that’s contained by two boxes — their car and
Bass notes — with their very long wavelengths — easily pass through wood and metal containers.
The best backboxes do reduce upper bass frequencies up to
9dB. That’s a significant reduction, to be sure (almost 65% of the sound is
trapped in the box). And yet these backboxes are unable to significantly reduce
low bass information, which easily pass through the walls of the house.
consider a subwoofer in a dedicated theater. Even when placed in a
well-insulated room, the rumble of the sub is heard throughout the house. This
is the physics of sound — bass notes, with their long wavelengths travel
freely. Backboxes help overall, but have their limitations.
Claim the space
During new construction, it’s important for the Integrator
to protect a defined area in the walls from pipes, conduit, and excess
insulation. A backbox is an inexpensive way to ensure other construction
elements don’t interfere with sonic performance and speaker placement.
Integrators like to be ‘first in line’ after studs are up to install backboxes,
helping the electrician and plumber plan their routes.
Protect from debris
Because most architectural speakers are open behind the
drivers, there’s a likelihood that construction debris and critters make
contact with the back of the speaker. In-ceiling placement is particularly
sensitive, since the debris rests atop the moving parts of the speaker,
rattling perfectly to the beat. Backboxes keep the back of the speaker clean,
while preventing critters from munching on critical components.