LOUDSPEAKERS

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Yoav Geva • YG Acoustics
Speaker Designer
Roundtable
Yoav Geva’s love of audio stemmed from a musical upbringing, while his
professional background grew from the study of complex algorithms
for digital signal processing. Not content to accept the compromises of
conventional wisdom, Geva set out correct what he viewed as weaknesses in the
design process of loudspeakers. He found that his understanding of digital signals
could be applied to analog waveforms (as used in speakers). Geva thus set out to
write his own software for speaker design—the first to optimize both the frequency
and time (relative phase) domains simultaneously. This technology created the
DualCoherent crossover now used in YG Acoustics speakers. After receiving a
grant for this award-winning technology, Geva now had the impetus to create a
company around his designs. YG Acoustics was thus born, in 2002. As he is only
35 years old, the story of Yoav Geva is still being written.
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
A small speaker can be designed to offer excellent sound quality.
Compromises are typically limited to one or more of the following three
areas: maximal output volume, bass extension, and sensitivity. The
reasons are simple physics: high output volume requires moving lots of air,
which in turn means a large driver-area and/or high driver-excursion. Since
in a small speaker large drivers are ruled out by definition, high excursion
is necessitated. This in turn requires the drivers to be more rigid to resist
flexing at high excursion, and thus they are inevitably heavier than would
be required if they didn’t need to maintain such stability. A heavier driver
reduces sensitivity because more amplifier power is required to induce
cone movement. As far as bass extension goes, the lower the frequency
being played back by the speaker the greater the driver excursion required
to achieve a given volume level. Bass extension is always directly at odds
with the maximal achievable output volume from a given speaker size.
As far as balancing the benefits, we chose a slightly different approach
for each of our models, depending on their typical application. For Carmel,
we chose a balanced approach of sensitivity and
output volume combined with near-full-range
bass-extension (35Hz) to offer a near-universal
speaker. For Kipod II we felt that it was critical to
offer full-range bass-extension down to 20Hz, so
we settled on optimizing it for small to mediumsized
rooms. For Sonja and Anat III we maximized
all parameters, so the overall size is larger, but
we still kept their monitor-sections small enough
to be stand-mounted and used as a stand-alone
compact speaker.
Do you have your own design techniques that
maximize the performance of small designs
We have developed specific technologies that
extract the most out of a speaker’s given size
in three main areas: drivers, cabinets, and
crossover circuitry. For drivers, as mentioned
above the key is high excursion coupled with
rigidity, while maintaining a low driver-mass to
28 Guide to High-Performance Loudspeakers www.theabsolutesound.com
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