JBL LSR 6328P Issue 35

John Gatski puts the new breed of JBL monitors through its paces.
BL entered the powered monitor game with its LSR
series about five years ago. But with the introduction of its latest generation powered monitors, it is
making a bold statement that the company is serious
about restoring itself to the top in professional speakers.
State of the Art
The LSR 6328P features JBL’s latest amp, crossover
and driver technology, plus the handy Room Mode
Correction (RMC) – see box item. I was also provided
with JBL's new sub-woofer, the LSR 6312SP, which
sports a 12-inch woofer/250W amp system and is said
to reach down to 26Hz.
The first thing you notice about the LSR 6328 is
how modern and state-of-the-art it looks. The speaker
contains an eight-inch carbon-fibre composite active
woofer (with JBL’s patented dual voice coil Differential
Drive technology) that is crossed over to a one-inch
titanium composite tweeter. These are integrated with
JBL’s Elliptical Oblate Spheroidal (EOS) wave-guide
that is said to ensure
maximum dispersion
in most studio environments.
A sixth-order
1.7kHz Linkwitz-Riley
crossover is used. The
low-frequency driver
is powered by a 250W
Class A/B discrete
amplifier. The highfrequency power is
handled by a 120W
Class A/B amp,
but is not
discrete (it's
a more conventional
amp-on-acard design.)
All tone tailoring, boundary compensation and level
controls are rear-panel mounted. They include the
power button, input trim, eight DIP switches – input
trim activation, +4dB input sensitivity, +8dB input sensitivity, Very Low Frequency (VLF) protect, –1.5dB low
frequency attenuation and –3dB low-frequency roll-off
attenuation boundary compensation (engaging both
switches delivers a –4.5dB attenuation), –1dB highfrequency attenuation cut above 2kHz, and a +1dB
high-frequency boost above 2kHz.
The speaker design incorporates a rear-mounted
port inside the amp cooling fins. Being Class A/B,
the speaker does generate some heat, but never to
the point of being too hot to touch. The ¾-inch MDF
cabinet measures 40.5 x 33 x 32.5cm and the speakers
weigh in at about 25kg.
JBL’s 30cm LSR 6312SP powered sub-woofer is an
amazingly good performer that will kick clean bass
out to 26Hz and it is not that big or heavy. The LSR
6328s can go down to 40Hz with decent output, but
the sub-woofer allows deeper low-end reproduction
for that 20Hz to 40Hz octave that comes into play with
electronic music and surround LFE effects. Crossing
over the low-bass duties to a sub also makes for a
cleaner-sounding woofer reproduction of mid-bass to
mid-range frequencies.
Hi-Res Imaging
I set the 6328s up as main monitors in a nearfield
configuration, mounted on custom speaker stands with
the speakers slightly toed in. Since the speakers have
impressive bass on their own, I decided to use them
mostly without the sub. Most of the audio came from
high-resolution sources, including DVD-A and SACD.
Sources included a Sony SCD-777ES – SACD player,
an Integra 8.3/Universal SACD/DVD-A player, Alesis
MasterLink and Panasonic RP91 DVD-A player. All
PCM sources (16-bit/44.1k through 24-bit/192k) were
digitally output through either a Bel Canto DAC-2
upsampling DAC or Benchmark Media DAC1 D/A
The speakers were placed in the centre of the room
about two metres apart and the listening distance
was about 1.5 metres away. In my setup, I ran a room
analysis using the Room Mode Correction kit that
came with the subwoofer. Since my room is rather long
with a concrete floor and a carpet covering, I do not
have much of a standing wave problem to correct at
the nearfield/midfield listening position. (There is some
loading up at the far wall where far-field listening is
done, but that listening position was never used.)
To witness the RMC in action I put the speakers
against the wall and moved my listening position to see
if the bass would load up; it did peak with a maximum
rise of +7dB, according to the RMC measurements.
After calculating the amount of EQ needed, I engaged
the RMC and the bloom was gone, thanks to the RMC’s
analogue EQ.
After testing the RMC, I moved the room back to
my normal setup distance. I sampled a CD of various
acoustic guitar cuts from my ’73 Martin D-35 (recorded
with Audix SCX-25s through The NightPro PreQ3
preamp). The audio was very real-sounding with a
smooth, airy, open quality that reveals the nuance
and harmonics of the aged guitar and bronze strings.
Imaging was just about as good as my Legacy Classic
II monitors and the D-35’s prominent bass was reproduced cleanly without artificial boom.
Next up was some high-resolution material –
courtesy of Tom Jung and other SACD producers. First
up was Jung’s SACD production of percussionist Steve
Davis’ Quality of Silence. The impeccably recorded
cymbals sounded incredible! The inner detail of the
transients was there, but never overly bright or harsh.
Even at loud levels, the cymbals did not fatigue the ear.
I sampled another SACD, The Anthony Wilson
Trio's Our Gang (Groove Note). The live-to-two-track
recording is a simple jazz trio: hollow-body guitar,
drums and Hammond B-3 (how analogue can you
get?) – and the JBLs shone. The Hammond B-3 sound
envelops you through the JBLs just as the recording
does through speakers three times the price.
I also found the LSR 6328s equally adept at handling
SACD classical recordings (strings, brass, woodwind)
with the same silky smoothness. Piano from several
recent Telarc classical SACDs and a demo DAT that
was recorded by a local musician showed the LSR
6328s to be first rate – no cabinet ringing or hollowness
that lesser speakers deliver with that instrument.
A word about the tweeter: JBL’s titanium composite
tweeter is very smooth compared to other metal dome
tweeters I have heard. For a powered speaker, violins
sounded about as smooth as I have ever heard them.
Ribbon-based systems from Legacy, Genelec, and
ADAM may be a touch smoother, but the ribbon models
I have auditioned are more expensive than the LSRs.
JBLs Bi-Amp System
In my room, the speakers provided as much level as
I needed and they never became harsh or distorted.
Since I am primarily a passive speaker/amp guy, I have
to admit that powered speaker amps, such as the LSRs,
are getting better.
In the pop genre, I listened to some mid-bass-heavy
hip-hop music, which can sound very muddy on lesser
speakers, but again, the JBLs handled the thumping
bass lines just fine. The speakers provide amazing
bass control from a woofer that is only eight inches in
diameter. Of course, the sub adds more low-frequency
extension and is a necessity if you work with LFE
effects, but I mostly used the LSRs without the sub.
Aurally, I found no fault with the JBL system. The
speakers are a tad heavy, with its sturdily built cabinet
and a beefy amplifier, but not unreasonable. Besides,
the built-in handles provide easy transport.
The only real quibble would be a desire for a frontmounted power switch.
Next Generation
In a nutshell, JBL is back. The new LSR series, powered
nearfield speaker is definitely one of the next-generation studio monitor lines to watch. At a reasonable
price with studio-flattering looks, the LSR 6328 speaker
sounds accurate with all kinds of audio. And its easyto-use, room tailoring controls and the optional Room
Mode Correction make it a system that can work just
about anywhere. Since the speaker goes pretty low for
an eight-inch woofer, the sub-woofer is just gravy…
This review first appeared in Pro Audio Review.
Distributed by
• Jands
Phone: (02) 9582 0909
Email: info@jands.com.au
Web: www.jands.com.au or www.jblpro.com
• LSR 6325P: $895; LSR 6328P: $2,995; LSR 6332: $3,195;
LSR 6312SP: $3,395
The ABCs of RMC
JBL’s Room Mode Correction (RMC) is a
handy, easy-to-use set of tools that allows for
reduction of the effect of the standing waves
that can make the sound boom and muddy.
It is an all-analogue, cut-only EQ, with adjustable frequency, width and depth controls.
The optional RMC kit includes a custom dB
meter with 9V battery, a test tone CD, a
frequency chart for plotting the results of the
pre-RMC measurement, a tool for adjusting
the speaker-mounted RMC controls, a width
template for ascertaining the broadness of the
peak (or dip), and a bypass remote control
to audibly confirm the unequalised vs. the
equalised or ‘corrected’ sound. The bypass
remote connects via a ¼-inch connector cable
(unfortunately not supplied with the kit). JBL
does supply a Y-cable to allow the bypass
switch to operate all speakers with RMC.
To use, pop in the test CD (with RMC controls
disengaged), play Track 1 to set the reference
level to �7dB, and then proceed to play the
bass tones that descend in order�from 126Hz
to 20Hz. Simply plot the dB level for each tone
from the meter on the frequency chart. Once
the tones are finished, draw a line to connect
the dots. That is your bass response curve in
your listening room. If the line is within ±3dB
of the reference level at each frequency, your
room is okay. If it is more, then you probably
need some room correction.
The adjustment equation’s key numbers
include the peak’s centre frequency, the level
in decibels (the difference from reference to
the actual peak level), and the width of the
peak. The latter is determined by placing the
width template over the chart and matching the
template curve to the peak. The peak’s width
value is assigned a percentage as figured from
the template.
To make the RMC adjustments for correction,
turn the width, centre frequency and depth
controls clockwise to the dial-designated
positions figured from the chart in the instruction manual. The depth control attenuates in
–1dB steps to –14dB. The frequency adjustment ranges from 24Hz to 96Hz.
After the adjustments are made, play the test
tones again, and the peak should be reduced
so that the audio sounds more natural when
real audio is played.
Since the LSR 6328 does not have as much
lower frequency content below 40Hz, JBL
recommends using the LSR 6312SP subwoofer (flat to 35Hz and an audible response
even lower), which has its own RMC. The
sub/main speakers can be adjusted in tandem
with the sub’s RMC. Using the LSR sub also
allows RMC with other speakers.
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