SPEAKER TONE CENTER
DR. DECIBEL
Does Size Really Matter?
The Role of Loudspeaker Diameter in the Relentless Pursuit of Tone
These days, guitar speakers are available in
a range of sizes from two or three inches,
right up to 15". Smaller speakers are great
for bedroom blasters and practice amps,
where reduced output at low frequencies
can minimize sound spillage between rooms
and keep the neighbors sweet. If you’re like
most, though, chances are you’ll be using 12"
speakers for much of your recording and live
work. But with an ever-increasing range of
quality 10" speakers, and even some interesting 15" speakers available, one has to ask the
question, “What role does speaker size play
in the ‘relentless pursuit of tone?”
Inside the Mind of the Speaker Designer
Practically all of a guitar speaker’s constituent parts contribute in some way to its sonic
signature. Chief among them are voice coil,
magnet assembly and cone [but also influential are the suspension, surround, dustcap,
cone treatments, etc.]. Each of these factors
interacts with the others, together contributing to overall tone. These interactions, though
in some cases very complex, are governed by
certain principles of physics, in particular:
Output level [a.k.a. sensitivity] is determined
by how efficiently the speaker converts electrical energy into movement of air.
Sound dispersion is controlled by the directional nature of high frequency sound and the
tendency of certain cone shapes to focus the
output signal in different ways.
52 PREMIER GUITAR DECEMBER 2009
This laser doppler image indicates vibration modes within
the body of the cone.
For guitar speakers in particular, vibration
“modes” within the body of the cone add much
of the harmonic complexity and coloration that
significantly contributes to great tone.
The speaker designer uses their expertise to
find the right mix of all of these factors to hit
a given “tone target.” Now, imagine we want
to use a small speaker with a thin and light
cone. There would be more intense vibration
modes within this type of cone [compared to
a cone of greater thickness, which would be
more resistant to these vibrations], resulting
in a richer, more harmonically complex tonality. However, use the same cone thickness
with a larger diameter speaker and that cone
might lack sufficient stiffness to withstand the
proposed power handling, and could buckle
under the force of the moving voice coil.
In this situation there would need to be some
“trade-off” between tonality and power
handling, requiring the designer to make
both musical and technical choices to reach a
desirable and workable solution. An experienced speaker designer will have the capability to identify the “right” choices to make in
these situations, and use the opportunity to
create a completely new sounding speaker.
What This Means For Tone
So, we see that attributes like size, harmonic
complexity, power handling and high-note
dispersion are clearly linked in the design
process. Over time, the 12" speaker has
come to be regarded as having the best balance of these attributes. However, 10" and
15" speakers can offer some alternative,
interesting and even exotic flavors!
Good sounding 10" speakers can deliver a
fast, punchy sound at wider listening angles
with reduced “boom” on small stages. They
can offer increased portability, reduced cost
and the ability to push your amp into overdrive at reasonable levels without having
drumsticks aimed at the back of your head.
A well-designed 15" speaker can move more
air so you can gig those wonderful little valve
amps. The vocal range can be creamier, with
extended low end and lots of detail and harmonic complexity, giving surprising richness
to some otherwise scratchy-sounding guitar
and amp combinations.
Which Size is For You?
It’s becoming more widely understood that
changing speakers has a greater impact on
tone than swapping guitar, pickup, or even
amplifier. So ask yourself, why just one size
of speaker? As players, all we need to do is
select the right one according to situation,
application … and desire.
Try this:
For the recording or practice session, why
not try a small amp through a sweet, well-balanced 10"?
At your big break support gig on the city hall
stage, how about a wall of 4x12s?
Need to add some beef to your retro “
plasti-caster”? Break out a 1x15 cabinet.
What’s more, just as boutique amp makers
have mixed different models to increase harmonic detail, you might even try and take this
a step further by mixing 10", 12" and even
15" speakers to create that unique signature
sound. But that’s another column.
Dr. Decibel
Dr. Decibel is the “public face” of the Celestion
Loudspeaker development team. Collectively, the team has
decades of experience, and are responsible for the creation
of some of the most iconic guitar speakers in history. For
any technical questions, contact drdecibel@celestion.com.
www.premierguitar.com
