Paul Bauman, associate director of Tour Sound at JBL, was instrumental in the
development at the VTX V20 system. With a master’s degree in physics and
electrical engineering and a prestigious background in line array development
spanning 20 years, Bauman is an industry heavyweight with much insight to offer.
Pro Systems caught up with him to pick his brain and to find out a little more about
what makes JBL and the V20 tick.

GB: You have quite a history in audio spanning over three decades, have a
master’s degrees in physics and electrical engineering plus you were involved in the
development of the L-Acoustics V-DOSC. What motivated you to get into audio?
Please provide a brief career history.

Paul Bauman: Like many people in this industry it began with a passion for music, a
fascination with the equipment that reproduces sound and the excitement of going
to see live performances. As a 16-year-old coming out of high school, those were
my first motivations. Looking back, I have been with JBL Professional for the past
eight years and am currently Associate Director, Tour Sound. Prior to this, I was
head of research and development (R&D) then director of technical support with L-
ACOUSTICS, based in France from 1998-2006; director of R&D with the Baltimore-
based tour sound company Maryland Sound International (1994-98); director of
engineering with Canadian manufacturer Adamson Systems Engineering (1991-94);
guest researcher at Chalmers University of Technology, Sweden (1991-92); and
senior research engineer with the Communications Research Lab at McMaster
University (1986-91). In addition to product and sound reinforcement system
design, over the past 30 years I’ve been active in sound design and system
engineering for touring, fixed installations and special events.

GB: In an interview in 2011 you mentioned that John Vanderkooy and
Stanley Lipshitz were influential in your journey as an audio specialist. Can you
please elaborate on that?

Paul Bauman: After completing an undergraduate degree in physics, I realised I
needed to specialise and while researching graduate study possibilities, I came
across the Audio Research Group (ARG) at University of Waterloo. I figured that if I
was going to specialise, it might as well be in something I’m interested in and, at
the time, Stan Lipshitz and John Vanderkooy were a unique team doing cutting edge
research in the areas of digital audio, recording techniques, loudspeaker crossover
optimisation and loudspeaker measurement. In 1983 compact disc had just come
out, it was the dawning of the digital audio era and the ARG had one of the first
portable digital recording systems in Canada (Sony PCM-F1) and the only Calrec
Soundfield microphone in North America for their research into Ambisonics. So in
addition to my research on loudspeaker measurement and digital signal processing,
I started assisting Stan on field recordings and campus radio broadcasts of chamber
music concerts. Having access to the equipment, I began doing live recording
projects of alternative music groups for my own interest and ultimately this led to
live sound reinforcement.

Readers should be proud to note that Stan Lipshitz is South African by origin and
recently the Toronto Chapter of the Audio Engineering Society held a tribute to the
ARG, inviting graduate students to talk about the difference that ARG made in our
careers. For those interested, please check out the Toronto AES website.

GB: You were a research engineer at McMaster University in the field of
mm-wave antenna technology which is similar in theory to line-source theory in
audio. How did this impact your career in loudspeaker system development?

Paul Bauman: At first it was hard to break into the pro audio industry and while
doing indie music projects on evenings and weekends, I was working as a research
engineer at McMaster University on mm-wave line array antennas for low angle
missile tracking including simulation of rough sea scattering conditions. With mm-
waves, the wavelengths are the same as audio frequencies – it’s just the speed
that’s different (light versus sound) – so the theory is directly applicable. That was
my day job and while at Mac, I re-discovered a great alternative music scene in
Hamilton. One of the bands I worked with (The Dik Van Dykes) grew in popularity
and started playing shows across Canada so I starting doing live sound for them and
got bit by the “big PA bug’ so to speak. Eventually I wound up joining the band for a
joke (it was a comedy punk act after all) and played bass on their second record so
I had a chance to experience things on both sides of the studio glass, onstage, as
well as at FOH (aside: check out the recent 24 year reunion / farewell show on
YouTube – hope you have a good laugh). Meanwhile, through my ongoing
involvement with the Toronto Audio Engineering Society chapter, I got to know
Brock Adamson and this connection led to my first step into sound reinforcement
manufacturing. From there I went to Maryland Sound International so I got to see
the industry from a sound company’s perspective and worked on proprietary
loudspeaker system designs while gaining valuable system engineering experience
on festivals, tours and installations.

GB: You were director of technical support at L-Acoustics. What were
some key experiences and lessons learned from working with L-Acoustics that aided
in the development of the VTX systems?

Paul Bauman: Following MSI I went to L-Acoustics in the very early days of V-DOSC
(the company had only 15 people when I arrived in France) and in some ways
became the “sound and voice’ of the company since I was responsible for product
and preset development as well as training and documentation. It was fun to be in
the ’right place at the right time’ since as V-DOSC took off, major touring accounts
and sound companies were approaching L-Acoustics to learn how the technology

They were busy and exciting times and it was all about managing growth of the
company and establishing the V-DOSC Network. Needless to say, being on the V-
DOSC selection committee with Michel Brouard and Christian Heil was an interesting
experience and so was keeping up with international training demands as new
sound companies came onboard.

Establishing the relationships with Lab Gruppen and Lake to develop a system
solution for V-DOSC was also a lesson learned about the importance of having a
system standard. The importance of modeling software in determining installation
parameters was also a lesson learned along with the experience of coding
Array2000 and storyboarding Soundvision. The value of training was also an
important lesson learned and having founded the V-DOSC training program at L-
Acoustics, it was recognised in the early days of line array that training was
essential since it was a completely different technology and it was important to
work correctly with it in order to get the best results.

Many people thought it was complicated, but once you got to know the simple
modeling and installation procedures, it saved time and allowed for better, more
consistent results. When I left L-Acoustics about 3 000 people had been through the
various training programs developed so that’s a source of pride. Gaining experience
working with line array technology and complementary fill from a creative sound
design perspective on numerous projects in the field also provided important
lessons learned.

Based on this experience, product manuals became labours of love that were
intended to explain how to work with these new tools and it was fun to come up
with new sound design approaches to disprove reactionary naysayers who were
claiming you can’t do this or that with line arrays. Key experiences came from
travelling the world, training various sound companies and meeting great people
while having the opportunity to work on sound design and system engineering for a
wide variety of touring, fixed installations and special events. Production credits
including: Rock in Rio 2001, Brazil; Dream Concert, Korea; Peter Gabriel Growing
Up Tour 2001-2003, Phil Collins First Final Farewell Tour 2004, Bob Dylan Europe
2005. I also consulted on sound design for Mamma Mia (four installations), Witches
of Eastwick, Turandot Stade de France, Jean Michel Jarre, Nine Inch Nails, David
Bowie, Neil Young, Radiohead, Bjork and Madonna, among others.

GB: With the ever increasing ubiquity of line arrays on today’s market and
arguably a similar increase in quality versus cost, what are the main challenges
faced by a loudspeaker system designer? Are all avenues toward creating the
’perfect’ line source almost exhausted? Please explain

Paul Bauman: I don’t think that all avenues are exhausted yet – there is always
room for refinement and a search for even greater perfection. There will be ongoing
improvement on the transducer side as new materials and concepts evolve – the D2
driver is a good example of that trend. You can always do things faster and more
consistently so there’s constantly room for improvement on the packaging and
installation side. Although it’s true that there are many good systems on the market
these days, ultimately it comes down to the operator (and the band of course) so
from the loudspeaker system design side it becomes more of a challenge in
developing the complete system – not just the loudspeaker alone – and giving the
operator better tools that are more convenient and easier to work with in order to
get more consistent results.

Modelling, measurement, EQ and control software, amplification, transport,
networking and DSP all play an important part in the system and having a tightly-
integrated solution with an intuitive, effective workflow-based user interface is key
to success. A strong training and technical support program to back it up is also
important. Apart from JBL Professional’s unique proprietary transducer technology,
one of the advantages of Harman Professional is the fact that all the pieces to the
VTX system come from legendary brands within the HPRO group. I like to think that
this gives us a unique opportunity to develop a more tightly-integrated system and
ultimately go further than our esteemed competition.

GB: What was the motivation behind developing the VTX as a successor to
VerTec? What shortcomings, if any, did you see in the VerTec that could be
improved upon and how did you solve these problems?

Paul Bauman: Refreshing the 10-year-old, full-size VT4889 VerTec Series model
with updated transducer technology, packaging and suspension was a natural
motivation and setting a new industry standard for high end touring with the VTX
System was the main goal. The VT4889 HF section was sonically solid and low
distortion due to the use of beryllium dome compression drivers but required
significant HF shelving eq to compensate for mass roll off effects and was
somewhat limited in power handling. As a result, the mid section was over-specified
and for V25 it was important to scale up LF and HF sections to improve the balance
of power resources between bands. This was achieved by introducing 2267H and
D2430K transducers, thus providing increased overall max SPL system output.

VT4889 enclosure height was reduced by about three 3 inches for V25 and this
combined with the new RBI waveguide design and relieved mid-high section with
optimised active radiating surface area improved vertical coupling from five to 10
degrees for V25. The RBI waveguide combined with V5 processing also provided
more stable horizontal coverage. Additional improvements such as the linear Angle-
Stop-Mechanism and dolly board were packaging-related to help speed up the
installation process. The design of VTX V25, S28 and G28 models began in 2010.

The waveguide for V25 evolved from the VT4886 and D2 Dual Driver development
began roughly four years ago from initial concept so we had a solid foundation to
work from. The design of other VTX System level elements such as JBL Line Array
Calculator, Crown Audio VRack and JBL HiQnet Performance Manager were under
development for 4-5 years and were fully mature so we had a solid turnkey system
package to coincide with the VTX V25 launch in 2012.

Prior to VTX development, another important consideration was to establish the
VerTec V5 system standard while ensuring future compatibility with the VTX System
standard, improving the performance of VerTec Series models to support current
owners, their customers and audiences worldwide while at the same time providing
an upgrade path towards VTX. Essentially, VTX is an entirely new Product Series at
JBL Professional and, as its name implies, is an extension of the VT Series. At the
same time, VerTec V5 is an extension of the VT Series since it is compatible with
the VTX System standard and complementary from a sound design perspective.

GB: The D2 driver and Differential Drive technology have been
revolutionary components in the VTX systems. Can you give an overview of their
operation and advantages over conventional drivers?

Paul Bauman: The D2 driver is a unique technology since the same large format
driver that is used in JBL’s flagship M2 Master Reference studio monitor for high
fidelity, critical listening is also used in VTX V25, VTX F12 and F15 enclosures for
high SPL sound reinforcement applications. The fact that the same component can
be used in these two applications with such different demands and requirements
demonstrates how versatile D2 technology is. It’s also a unifying technology since
there will be consistent sound quality between what the artist hears in the studio on
M2 monitors, what they hear onstage through F12 or F15 stage monitors and what
the audience hears out front through VTX V20 or V25 FOH systems.

The D2 Dual Diaphragm Dual Driver merges two compression drivers into a single,
compact transducer. Two lightweight, polymer material, annular diaphragms with a
V-shaped profile and dedicated phase plugs are employed in the D2 transducer. The
two annular diaphragms have the same effective radiating surface area as a
traditional dome diaphragm, thereby providing equivalent SPL output. There are
three main benefits to the D2 approach: 1) two separate voice coils provide twice
the power handling capacity combined with reduced power compression and
increased dynamic headroom due to improved heat dissipation; 2) the lower moving
mass of two annular diaphragms has improved high frequency extension in
comparison with the heavier dome diaphragm assembly; and 3) dome breakup
modes that result in frequency response irregularities and increased non-linear
distortion at high frequencies are virtually non-existent for the D2 driver due to the
use of annular diaphragms and the polymer diaphragm material itself.

For readers who are interested in complete technical details, please refer to the
following Audio Engineering Society preprints: ’Dual Diaphragm Compression
Drivers’, October 2011 and ’Application of Matrix Analysis to Identification of
Mechanical and Acoustical Parameters of Compression Drivers’, October 2013. Both
of these preprints were authored by Dr Alex Voishvillo, Senior Transducer Engineer
at JBL Professional and inventor of the D2 driver.

GB: The VTX V20 was recently launched. Is it just a scaled down version
of the V25 or does it feature any new innovations? Please explain.

Paul Bauman: Despite the success of VTX V25, there is a limited amount of demand
for large format line array systems and many of our customers were requesting a
smaller format VTX line array that would be more suitable for a wider range of
applications. Since we had recently refreshed VERTEC VT4888 (2x 12′) and VT4887A
(2x 8′) models with V5 processing upgrades and these models are still both very
relevant and popular in the market, the goal was to introduce a 2x 10′ model since
this is a format that JBL has not offered in the past. The concept was to develop a
compact, high power density enclosure that would be suitable for use as a
standalone FOH system but could also be used to complement main LR V25 arrays
when V20 is used as a center cluster, offstage / outfill arrays or as a downfill
enclosure suspended underneath V25. The compact V20/S25 format is ideal for use
in theater and performing arts center applications as well as compact; low-profile
stacked or suspended sidefill monitoring. Using the same 15′ transducer in V20’s
companion subwoofer VTX S25 as is used in VTX V25 also helped to ensure sonic

VTX V20 features the same advanced technology and performance of the
groundbreaking VTX V25 in a smaller format, high power density (nine transducers,
14 voice coils total), true three-way design, complemented by a new suspension
system that provides efficient transport, fast setup and precise configuration. Many
people are just as excited by the suspension system as they are by the sound
quality, coverage / throw and output capacity of V20. The horizontal pattern control
is extremely stable and provides precise, accurate coverage with exceptional stereo
imaging. Effective line source array coupling has been achieved in the vertical plane
from 0 to 12.5 degrees and V20 delivers linear, transparent sound up to surprisingly
high output levels and throw distances for its compact size. The key differentiating
feature is a new small format version of the patented, D2 Dual Diaphragm Dual
Voice Coil High Frequency (HF) compression driver. Using two annular, ring
radiators with separate voice coils and magnetic motor structures results in twice
the power handling, extended HF response due to the lighter moving mass of the
two diaphragms in comparison with a standard dome compression driver and
significantly reduced distortion above 10kHz due to the absence of dome breakup
modes. Three small format D2 drivers, combined with new ultra-linear 4-inch Mid
Frequency (MF) and 10′ Differential Drive Low Frequency (LF) transducers comprise
V20’s 3-way system design and the power density that has been achieved provides
output that approaches what other competing 2×12′ systems can deliver.

GB: Do you feel line source systems are still at the cutting edge of live
sound reinforcement? Where do you see the sector moving in the next five to 10
years and what other innovations can we expect in the future given the advances of
discrete DSP-driven systems and the ever increasing ability to control coverage?

Paul Bauman: Yes – line source systems are still very much at the cutting edge of
live sound reinforcement. I think we will see a continuation of the ongoing shift
towards more tightly-integrated, turnkey packaged systems. Since tour sound tends
to be relatively conservative in adopting new technologies I don’t anticipate any
radical shifts in direction just ongoing, incremental improvement and refinement of
existing technologies. We’ll continue to develop tour sound products that feature the
innovative transducer technologies that JBL Professional is known for while
leveraging and building upon the system-level infrastructure that we has already
been put in place.

Advanced simulation, equalisation and measurement tools implemented via JBL
HiQnet Performance Manager, comprehensive training and improved levels of
integration between JBL loudspeakers and other technologies within the HARMAN
family are additional areas of development. I’m particularly excited about our
recent acquisition of Duran Audio and the possibilities that their industry-leading
expertise in digital beam forming and beam steering will bring to future system
developments. Watch this space!