JBL are the initials of founder James Bullough Lansing, the ex-vice president of
engineering at famed audio equipment pioneering company Altec Lansing and
founder of JBL. Since 1946, JBL has been making professional audio products that
have, at one point or another, been encountered by anyone who works in the pro
audio industry from the recording studio, to the live sound sector, to the OEM sector
and even in the consumer market. In a word, JBL products are ubiquitous and have
been for well over 70 years.

Some history

The story of James B Lansing is a sad one. In his time during the “40s he was well
known as a highly innovative engineer but, sadly, wasn’t a very good businessman.
Despite developing many robust loudspeakers that had enormous market longevity
– some well into the “70s – during his short tenure with his newly formed company
he struggled to pay his creditors and failed to ship enough product out the door. The
stress of it all, and no doubt an inherently depressive nature, led to his tragic
suicide on 4 September 1949.

But this was not the end of JBL. In fact, this turning point causes one to wonder:
had Bill Thomas, his successor, not taken over and used the $10 000 life insurance
policy that Lansing had left to the company to revitalise it, how much of an impact
would that have had on pro audio today? In my mind, the consequences would have
been devastating because, as time would tell, JBL virtually became a household
name (and later on quite literally did) and its products played a vital role in the pro
audio industry for many decades.

Indeed, by 1977 – arguably a “golden era’ in rock and roll – more recording studios
were using JBL monitors than any other brand and their loudspeakers were found all
over the touring community. This must have had an immense bearing on much of
the music from that era that we now treasure and it could be said that we can owe
it all to that $10 000 left by Lansing.

Of course, JBL was eventually bought from Thomas by Harman in 1969, then called
the Jervis Corporation, and has been under their umbrella ever since. This makes
them one of the longest standing Harman companies and, combined with Lansing’s
innovations, has a long and rich heritage upon which to build upon. And, man, are
they building upon it!

JBL loudspeakers and line arrays are a virtual standard in many touring circles
today. Their VerTec line-source systems have been used on countless rock and roll
tours and are known for their big, powerful sound in that genre. But, as time
marches on the new builds upon the old and next generation products start to
emerge so the successor to the VerTec became the large-format VTX V25, a huge
step forward in JBL’s repertoire. The VTX V25 featured a slew of new, patented
technologies that improved upon the design of VerTec and included the pivotal dual-
diaphragm D2 high frequency driver and their Differential Drive technology, which
found its way into JBL’s next generation woofers.

Leading on from that success, JBL recently released a new, mid-format line array
called the VTX V20, with its accompanying subwoofer, the S25. This fills a gap
between their small format VRX series and the V25 behemoth and gives rental
companies and installers the opportunity to satisfy their customers’ needs more
effectively. So, without any further ado, let’s take a look-see, shall we?

The V20 and S25

Paul Bauman, associate director of Tour Sound at JBL Professional, said of the VTX
V20 and S25 during its launch at NAMM 2014: “In its short history, the VTX Series
has already proven to be the world’s highest-performing line array system, as
evidenced by its rapid adoption and deployment on some of the world’s most
successful tours and most prestigious venues. The new V20 and S25 deliver the
same level of performance that is characteristic of the VTX Series while adding
even more flexibility due to their compact form factors.’

The V20 is a true three-way system. It features a scaled-down version of its
proprietary D2 dual diaphragm, dual voice coil compression driver, which is a huge
innovation in and of itself and, as with the V25, includes JBLs patented Differential
Drive woofers, also featuring dual voice coils and ultra-linear motor midrange
drivers. More specifically, the V20 features two 10-inch 2261H Differential Drive
woofers, four 2164H four-inch ultra-linear midrange drivers and three smaller form-
factor D2415K high frequency drivers.

The D2 is probably the most noteworthy innovation found throughout the VTX series
that, in essence, merges two compression drivers into a single unit and combines
their output. Each voice coil has its own magnet assembly and specialised phase
plug so instead of utilising one heavy, single dome diaphragm and voice coil
assembly it implements two lightweight ring radiator diaphragms with dual voice
coils that exit through the same chamber. However, to understand why JBL took
this approach, you have to understand what the disadvantages of traditional dome
diaphragm, single voice coil dome compression drivers are.

Traditional single-dome compression drivers suffer from several drawbacks and
most well-known of them is a phenomenon called the “mass break point frequency’.
This phenomenon exhibits a 6dB/octave high frequency roll-off as a consequence of
the moving mass of a radiating diaphragm. The rule of thumb here is that this
frequency decreases (becomes lower) as the mass of the diaphragm increases.

Therefore it stands to reason that lighter, faster moving diaphragms produce
superior high frequency reproduction. The caveat, however, is that small, light
diaphragms can’t produce the SPL required by long-throw applications in touring
sound systems so a balance must be struck between performance and diaphragm
size and weight. In a general sense, the frequency at which most traditional
compression drivers reach their mass break point is at 3.5kHz and above that
frequency the response rolls of at 6dB / octave. This is then “corrected’ via EQ and
the obvious trade-off is reduced amplifier headroom. Additional equalization is also
required to offset air absorption over long throw distances and this also impacts
amplifier headroom. Dome break up modes at high frequencies are another
limitation of dome compression drivers and these break up modes are responsible
for increased distortion at higher frequencies – typically above 12kHz.

The D2 attempts to remedy these limitations by combining the output of two low-
mass diaphragms mounted coincidentally in the same structure by the
implementation of specialised phase plugs that achieve phase coherence at the
output of the driver. This also means that the mass break point frequency is shifted
significantly higher which in turn produces an exceptionally flat high frequency
response without the need for extreme compensatory EQ. Additionally, this means
that the system amplifiers work more efficiently which results in more available
headroom plus, since there are two voice coils, power handling is doubled. The ring
radiator topology does not suffer from dome breakup modes of traditional dome
compression drivers so clean, distortion-free high frequency reproduction is another
important benefit.

Coupled to the three D2415K high frequency drivers is JBL’s new Radiation Boundary
Integrator (RBI) wave guide. As most people know who are intimately familiar with
line-source loudspeaker design, the wave guide is an integral component when
attempting to achieve an isophasic, cylindrical wave front and is a huge part of
what gives a line array its “sound’, clarity and throw. RBI technology combines the
high frequency and midrange drivers to achieve uninterrupted transmission across
each band that is distortion-free and seamless. Essentially, the midrange drivers
are mounted into the walls of the HF wave guide which features specially placed
slots where the midrange band exits. A patented and tuned resonant chamber is
also integrated into the wave guide, which JBL claims eliminates ’throat-related
cancellations due to back pressure from the midrange section”. The RBI wave guide
employed in VTX V20 supplies stable horizontal coverage across 100 degrees and
line source array coupling from zero to 12.5 degrees in the vertical plane.

Specifically designed for easier transport, speed of installation, handling and re-
configuration, a notable new addition to the VTX range is JBL’s ASM Suspension
System. ASM stands for “Angle Stop Mechanism’ and this rotary cam works in
tandem with fully captive hinge bars. This allows relative enclosure angles to be
rapidly configured during array deployment.

There are two modes of operation for the ASM system: compression mode, which
utilises a rear pullback motor or hand hoist to set inter-enclosure angles; or fixed
angle mode, which secures angles via quick-release pins. During strike, the ASM
system can be reset to zero with ease.

In addition to the ASM system, a brand new array frame and extension bar is
implemented into the suspension system. This provides a new level of flexibility in
either operation mode or when stacking because of the tilt adjustment facility
incorporated into the design. The V20 will also be able to be suspended below the
V25 for down-fill applications in the future as an adapter frame is in the works.
The S25 is the companion subwoofer to the V20 and features two Differential Drive
15′ 2000W drivers. Indeed, these are the exact same drivers found in the V25 mid /
high enclosure, maintaining coherent sonics across the range when combining the
systems. The S25 is cardioid array-ready and can be flown in a variety of
configurations; beside, behind, in the middle, or at the top of the V20 arrays in
either end-fire or cardioid mode for enhanced pattern control and rear rejection.

The wrap

The JBL VTX V20 fills the much needed gap between the relatively small and now
aging VRX and the massive VTX V25 line-source systems. It features many patented
designs and innovations that build upon the rich legacy of JBL Professional and,
given that all of these technologies, such as Differential Drive and the D2 driver,
can be found in the V25, sonic signature “linearity’ is almost certain across the two
systems. JBL, I’m sure, will continue to create and innovate and given their
heritage, one can only surmise what their future will hold.