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Paul Barton • PSB Speakers
Speaker Designer
Roundtable
Paul Barton, founder and chief designer of PSB Speakers, began designing
speakers more than 40 years ago for a Grade 10 Physics project. His
engineering bent coupled nicely (for speaker designer purposes) with his abilities
as a violinist, who as a young musician played with Canada’s National Youth Orchestra
and the University of Toronto’s Repertoire Orchestra. His two passions converged
permanently in 1972, when he founded PSB Speakers.
One of the first to use the anechoic chamber at Canada’s renowned National
Research Council facilities in Ottawa and other facilities there, Paul has combined
research into the correlation of measurements and audible performance with testing of
successive modifications of every speaker in process.
In the mid-1980s, PSB became part of the Lenbrook Group of Companies, whose
expertise in marketing specialized electronic products and widespread distribution in
North America and around the world has established PSB Speakers as one of the most
respected international loudspeaker manufacturers worldwide.
What are the particular challenges and trade-offs of designing a
small loudspeaker Which sonic qualities are you primarily trying to
optimize, and which qualities are you most willing (or compelled) to
give up
The most challenging aspect of a small design is the ability for the
small form factor to produce full-scale musical events realistically, both
for loudness and dynamic range. This is even more challenging when
the music contains wide bandwidth especially at low frequencies. One
must remember that as the frequency is halved
the excursion requirements for the woofer must
double to maintain flat response. This means that
a small speaker can produce very low frequencies,
but can also be very strained if the low frequencies
it is asked to reproduce are played too loud. The
smaller size can also result in a design that is less
efficient than a larger design. This means that you
need more power to drive the small design to the
same volume level as a full-sized speaker system.
I am willing to compromise these things, but I
like to think of a small design as the challenge of
balancing all of these limitations. For me this has
come from a lot of trial and error over my 40-year
career in loudspeaker design.
Do you have your own design techniques that
maximize the performance of small designs
One technique that I like to use to
overcome the small size and realize
a bigger sound than one would
expect from such a small enclosure
is the use of a Neodymium booster
magnet on top of the woofer’s pole
piece inside the voice-coil former.
What this does is increase the force
in the magnetic gap around the
voice coil and results in more sensitivity
and deeper bass response for
a given box volume/size. In theory,
if you increase the magnetic force
around the voice coil to an infinite
amount you can decrease the box’s
air volume to nothing and maintain
the same frequency response.
Has your design work on larger
loudspeakers informed your
approach to stand-mounted
ones
I sort of see the reverse influence
because small two-way designs
have been helpful in keeping me
grounded as to the basic rules
that apply to good, cost-effective
designs of any size. For me, a
small-system design sets the bar
for what you can do for a given
amount of money and therefore
puts things in perspective for what
can be justified in cost for larger
speaker systems.
What, if any, sonic and technical
advantages do small two-ways
have over larger multiway
systems
The main advantage, whether
intentional or by default, is the
fact that the drivers (woofer and
tweeter) must be close together,
and along with the selection of the
proper crossover frequency, can
produce a coherent integration
of the woofer and the tweeter at
the crossover frequency. What I
mean by this is if the drivers are
physically closer together than the
wavelength of the frequency that
they both produce at the crossover
point then the drivers together
behave as a single source,
which is what you want. It is also
desirable to choose the crossover
frequency where the woofer, at
its highest operating frequency,
has similar dispersion to the
tweeter at the same frequency
(its lowest operating frequency
in the system). This approach
always results in amazingly natural
timbre, wonderful soundstaging,
and very flexible positioning of the
listener (seated or standing) and
positioning of the speaker itself in
your listening environment.
25 Guide to High-Performance Loudspeakers www.theabsolutesound.com
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