Martin Audio WLXGS User manual

The Martin Experience
WLX, WLXGS
User’s Guide
PREMININARY INFORMATION
All material © 2007. Martin Audio Ltd. Subject to change without notice.

Wavefront WLX and WLXGS
Hybrid™ Subwoofer
Preliminary information
Introduction
The powerful WLX Hybrid™ subwoofer is designed to complement Wavefront W8L Series touring systems
to provide deep bass with maximum efficiency.
WLX
Rigging options
Standard WLX subwoofers are equipped with integral flying hardware. A non-flying version is available –
the WLXGS (= WLX Groundstack).
Standard WLX subwoofers may be flown from a standard W8LC grid via a single point W8LC lifting bar.
W8LC Grid W8LC Lifting Bar
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A combined WLX/W8LM grid (ASF20003 – not shown) has been designed to enable W8LM miniature line
array elements to be flown beneath standard WLX subwoofers.
Rear connector brackets (ASF20005) are also available for flying W8LC compact line arrays below WLX
subwoofers. ASF20005 connector brackets enable WLX subwoofers to be angled downwards with respect to
the W8LC compact line arrays to ensure optimum audience coverage.
Connector Bracket Application example
For detailed rigging information, please see the WLX Flying Manual.
Specifications
Freq response: 35Hz - 150Hz +/- 3dB (half space)
Rated Power: 1000W into 8 Ohms, 4000W peak
Sensitivity: 106dB (half space with band limited pink noise)
Maximum SPL: 135dB continuous, 141dB peak (half space with band limited pink noise)
Impedance: 8 Ohms nominal
Connectors: 2 x Neutrik NL8 or PAcon to special order
Dimensions: (W) 1002mm x (H) 490mm x (D) 800mm (950mm with wheelboard)
(W) 39.45ins x (H) 19.3ins x (D) 31.5ins (37.4ins with wheelboard)
Weight: 89 kg (196 lbs)
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Pin-outs and cabling
WLX Input
NL8 WLX
-1 Driver – (& link -1)
+1 Driver + (& link +1)
-2 Driver – (& link -2)
+2 Driver + (& link +2)
-3 link-3
+3 link+3
-4 link-4
+4 link+4
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Cable and panel connector part numbers
Please note the following part numbers when ordering loudspeaker connectors to make up cables and patch
panels
Neutrik NL connectors
NL8FC 8 pole cable (female)
NL8MPR 8 pole panel (male)
NL8MM 8 pole inline coupler (male-male)
Connectors should be kept in good, clean, uncorroded condition to ensure full, undistorted loudspeaker
performance. Corroded or damaged pins and sockets can cause severe distortion or loss of signal.
Recommended loudspeaker cable
Although only 4-core cable is required for WLX subwoofers, many users will find it convenient to
standardise on 8-core NL8 cables to avoid confusion when using other loudspeakers in the Wavefront range.
Note that pins 3-, 3+, 4-, 4+ are hard wired to the link connector to allow through wiring to, for instance, a
W8LM system via the extra cores.
Cable run vs copper core cross sectional area
Single WLX Two WLXs paralleled
Up to 50m 2.5mm² 6mm² (or 2 x 2.5mm² cores in parallel)
Up to 100m 6mm² 10mm² (or 2 x 6mm² cores in parallel)
Q. Why the odd sizes?
A. Loudspeaker cables are available in a limited range of standard copper core sizes -
ie. 1.5mm², 2.5mm², 4mm², 6mm², 10mm² and 35mm².
Controller settings for Wavefront WLXs
Standardising on one good model of power amplifier (preferably the Martin Audio MA4.2S set to 32dB
voltage gain and 0dB MLS) and correctly set-up controller (preferably the Martin Audio DX1 or the XTA
DP226) will provide the most dynamic system performance and protection whilst simplifying design and
reducing spares inventories.
A WLX crossover is included in the standard Martin Audio W8LM preset. Binary files and an AudioCore
library file, complete with loading instructions, are included on the Martin Audio User Guides CD.
For other combinations read on…
All material © 2007. Martin Audio Ltd. Subject to change without notice.

Sub-woofer crossover and alignment
Crossover frequencies
The original factory controller settings for W8L, W8LC and W8LM systems are intended for use with sub-
bass systems such as the W8LS, WLX or WSX.
As a consequence LF high pass filters should be set as follows:
Loudspeaker Type Default (with subs) Full-range (without subs)
W8L 35Hz* 24dB/8ve L-R
(assuming stacked WLXs)
*Use 60Hz when used
with W8LS direct
radiating subs
25Hz 24dB/8ve L-R
W8LC 60Hz 24dB/8ve L-R 30Hz 24dB/8ve L-R
W8LM 70Hz 24dB/8ve L-R 30Hz 24dB/8ve L-R
Note that the W8L system’s LF response extends down into the low bass region. For maximum Heavy Metal
or Dance headroom a substantial mid-bass overlap can be allowed when horn-loaded W8L main systems are
used with horn-loaded sub-woofers such as WLXs.
Compact systems like the W8LC and W8LM are designed to run with minimal overlap. They are always
high-passed at 60-70Hz when used with sub-woofers.
Time alignment
W8L, W8LC and W8LM inter-driver delays
Standard Martin Audio presets apply small output channel delays to DX1 or DP226 controllers to align the
multiple drivers within W8L, W8LC and W8LM cabinets.
These inter-driver delays are not user adjustable. They have a strong influence on a system’s off-axis lobe
structure in addition to the usual on axis performance alignment.
Very important note!
Crossover frequency and phase settings should never be adjusted to compensate for room anomalies.
Controller input equalizers or external equalizers (or, in an ideal world, room treatment!) should be used for
that purpose.
Controller Reference Delays
The multiple driver delays in standard Martin Audio presets are “Lock Linked” to a particular crossover
reference delay channel. In the absence of any main (W8L, W8LC) delay requirement, the W8L and W8LC
reference delays default to zero because they relate to the LF horn drivers whose acoustical centre is furthest
from the cabinet grille – i.e. the driver that every other driver in the cabinet gets delayed to.
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W8LM presets include the WLX sub-woofer so they have two (mono) or four (stereo) unlocked delays. The
WLX channel defaults to zero because the WLX has the longest horn. The W8LM LF/Full-range and HF
reference delays default to 3.931mS and 3.829mS respectively to time align the W8LM to the WLX when the
grilles are aligned.
W8L, W8LC & W8LM reference delays and Sub-woofer delays are left unlocked to allow users to align
main systems and sub-woofers if placement causes misalignment. The “Lock Linking”, mentioned above,
ensures that all the drivers in a cabinet track the reference delay and maintain the correct inter-driver
alignment.
Standard reference delay channels are as follows:
W8L Series Reference delay channels (left
unlocked for
main-to-subwoofers
alignment)
Functions
W8L 1 LF
W8LC 1 LF
W8LM (Active mono) 1
4
WLX
Lower HF
W8LM (Passive mono) 1
2
WLX
Lower full-range
W8LM (Active stereo) 1
3
4
6
Left WLX
Left HF
Right WLX
Right HF
W8LM (Passive stereo) 1
2
4
5
Left WLX
Lower left full-range
Right WLX
Lower right full-range
Alternative W8LM + WLX presets are now available. These provide a separate sub-woofer signal
chain via controller input B and output 6. Reference delays for these main+sub input set-ups are as
follows:
W8LM + WLX Reference delay channels (left
unlocked for
main-to-subwoofers
alignment)
Functions
4W8LM + WLX
(Active mono - configured upper
& lower for possible flown +
stacked use)
6/8/12W8LM + WLX
(Active mono)
6
3
4
6
4
WLX
Lower HF
Upper HF
WLX
Lower HF
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Main to sub-woofer delays
Reference settings
The following table shows system delays to align various combinations of W8L Series main and sub-woofer
system. These should be treated as important initial settings and will work without further adjustments where
grilles are alignment. They are a good starting point for further time alignment.
The main W8L, W8LC and W8LM parameters will already exist in the standard presets but you will need to
check the user adjustable HPF (High Pass Filter) and Delay (grilles aligned) are set according to the table.
Sub-woofers usually take their signal from a separate controller for W8L and W8LC systems because our
standard band zoned presets use all six bands.
The WLX sub-woofers signal will be on controller output channel 1 for standard W8LM set-ups. The WLX
signal will be on channel 6 where a separate sub-woofer mix is to be used using a W8LM + WLX
configuration.
All material © 2007. Martin Audio Ltd. Subject to change without notice.

In all cases, set the main (W8L, W8LC or W8LM) and sub-woofer controller output parameters as follows,
making sure that controller inputs are initially set flat (no equalisation), 0dB gain, 0ms delay.
Flown WLXs
Side-by-side arrays
Similar length (height) sub-woofer arrays should be placed beside the main system for consistent
performance and maximum impact throughout the audience area. ViewPoint™ should be used to design
matching arrays using the Match WLX function . . .
10 x W8LC 7 x WLX
Typical 10 x W8LC + 7 x WLX side-by-side arrays for high power music applications
Mixed arrays
Sub-woofers may be flown above smaller main systems using W8L Series flying systems or adaptors.
ViewPoint™ should be used to ensure system safety . . .
4 x WLX + 8 x W8LC mixed array for orchestral applications
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4 x WLX + 8 x W8LC mixed array for orchestral applications
using Connector Brackets – ViewPoint™ Rigging View
Stacked WLXs or WLXGSs
WLX or WLXGS subwoofers may be ground stacked below the main system. Ground stacked subwoofers
can be up to 6dB more efficient than flown systems – assuming an acoustically solid floor - thanks to half
spaced boundary conditions. A solid floor can act as an acoustic mirror, doubling the effective array size.
All material © 2007. Martin Audio Ltd. Subject to change without notice.

Stacked system alignment
A stacked subwoofer system should be placed directly beneath the main system with the subwoofer and main
system grilles vertically aligned.
Subwoofer grilles and main system grilles should be closely aligned so that they are at equal distances from a
central audience area – preferably a well positioned mix position.
If systems have to be physically misaligned, extra delay may be employed to compensate for the differing
arrival times.
Please note:
Electronic delay can only compensate for physical misalignment with reference to a specific listening area -
usually a listening reference point eg the mix position. In the following example, aligning for maximum
impact at the mix position will compromise bleacher impact and vice versa.
All material © 2007. Martin Audio Ltd. Subject to change without notice.

WLX sub-woofers may be time aligned without test gear as follows:
1) Start with the controller outputs delays set as per the above table
2) Use a laser tape measure to measure the distance to the main system grille and the WLX sub-woofer grille
3) If the WLX sub-woofers are closer than the main system, increase the WLX controller output delay (2.91ms for
every meter of misalignment)
4) If the main system is closer than the WLX sub-woofers, increase the main system delay (2.91ms for every meter of
misalignment)
5) Fine adjust the delay by switching the WLX sub-woofers to reverse polarity, listening to a 70Hz tone and adjusting
the delay for a dip in level
(Note: You MUST complete steps 1-3 before fine tuning!)
6) Don’t forget to switch the WLX sub-woofers back to normal polarity for maximum summation and impact!
Power amplifier recommendations
The Wavefront WLX Subwoofer has been designed and manufactured for very high performance but will not
give that performance unless power amplifiers are chosen and used intelligently.
Power capability
WLXs provide full performance when driven by professional power amplifiers capable of delivering
undistorted output power into a range of loads as follows:
WLX
1,150 W (AES) into 8 Ohms
2,300 W (AES) into 4 Ohms
and
2,900 W(AES) into 2 Ohms
Please note:
Amplifiers with excessive output may damage voice-coils or age driver suspensions due to excessive heat
dissipation and excursion.
A note about power amplifier output specifications
Most power amplifier manufacturers keep their costs down by using unregulated supply rails which sag
under load. To allow for this sag, manufacturers set their rails high so that they still meet their quoted output
into specified loads. These high rail voltages allow such power amplifiers to provide outputs 1.5 - 2 times the
power quoted for short-term bursts. Martin Audio products will withstand this potential doubling of
instantaneous power - with suitably set controller limiters - but further, long-term increases caused by over-
sized amplifiers should be avoided.
Martin Audio MA series power amplifiers have regulated rails so it is quite permissible to use slightly
All material © 2007. Martin Audio Ltd. Subject to change without notice.

overpowered models - with suitably set controller limiters - without risking uncontrolled power bursts. The
MA series power amplifiers’ regulated power rails also ensure maximum performance under the real-world
concert conditions of less-than-optimum mains supplies and low impedance loads.
Amplifier load tolerance
An efficient subwoofer system in live concert conditions can act as a surprisingly dynamic and complex load.
Most modern touring power amplifiers claim 2 Ohm capabilities but make sure your amplifier is also capable
of driving reactive (ie inductive or capacitive) loads without prematurely clipping or developing output stage
crossover distortion.
Mains safety!
A fully qualified technican should check mains safety and phase voltage before the system is patched.
Power reserve
Most power amplifier specifications are based on bench measurements made using stable, high current mains
supplies and well defined loads. Amplifiers sound best when they have plenty of current in reserve for
percussive peaks and sustained bass notes.
1) Try to ensure that the mains supply stays within the amplifier manufacturer’s specified range from no
load to maximum load.
An electrical technician should check the supply vs demand using an accurate voltage meter.
2) If unfamiliar generators are being used the electrical technician should check the mains waveform
(using a portable ’scope-meter) to make sure that it is sinusoidal and not crawling with spikes or
interference.
3) Avoid driving too many WLXs in parallel. I would suggest no more than two (giving 4 ohms) so that
the power amplifier’s 2 Ohm spec is kept in reserve for musical peaks.
4) Avoid using power amplifiers in bridged mode. Most commercial power amplifiers are optimised for
2-channel operation. It is usually better to use the appropriate amplifier in 2-channel mode than to use
an inadequate amplifier in bridged mode.
Gain and level settings
Gain switches
If you are lucky enough to have amplifiers with user gain switches, set them all to identical positions. A
voltage gain of 32dB will match the default controller presets and will provide a good balance of system
headroom and noise (assuming professional audio equipment is in use FOH).
Level controls
The front panel level controls should be turned down (fully counter clockwise) until FOH-to-Amp rack lines
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have been checked and controllers have been set to suit the power amplifiers to be used. Music should be
used to check that controllers are receiving and sending the appropriate signal bands and then each power
amplifier level control advanced in sequence to check system operation and patching.
Assuming that controller output levels and limiters have been left as recommended for WLX subwoofers,
power amplifier level controls should be set to full (fully clockwise).
Rack mounting
As with other systems, always leave a 1U space between subwoofer power amplifiers and controllers.
Although most modern amplifiers don’t radiate significant fields it's better to play safe and keep the system
free from hum & buzz. Rear supports are recommended. Check the manufacturer's application notes for
details.
Placement
Flown WLX subwoofers provide maximum integration with Martin Audio W8LC or W8LM line arrays but
efficiency can suffer due to the lack of ground loading. ViewPoint™ should always be used to ensure
maximum safety.
As mentioned earlier, ground stacking WLX or WLXGS subwoofers will provide maximum efficiency but a
solid floor is essential for good dynamics.
WLX/WLXGS horns flare from the label end. They can be symmetrically coupled by placing them label-to-
label.
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Symmetrically coupled 2-wide columns show a slight improvement in mid-bass amplitude and polar
response - but the effect becomes insignificant in large, flat fronted arrays or widely spaced stage apron
systems.
2-wide symmetrical columns of WLX/WLXGS may be horizontally arrayed to improve mid-bass coverage.
Array shapes vs coverage
WLX or WLXGS subwoofers may be stacked and arrayed in various configurations to increase sound
pressure and tailor coverage. The sound pressure increase is intuitive but the significance of subwoofer array
shapes and sizes is often overlooked.
The following table shows the sound pressure boost and coverage provided by a variety of flat fronted
arrays:
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Array Approx Boost Horizontal Vertical
(wrtsingleunit)coverage coverage
- Wide Wide
+12dB Wide Narrow
+12dB Narrow Wide
+24dB Narrow Narrow
In these examples “wide” means that there are no coverage nulls within the forward 180º at mid-bass
crossover frequencies. Wide coverage arrays have significant output beyond 180º making them more prone to
room colouration.
“Narrow” means that coverage will drop significantly before 180º coverage is reached at the mid-bass
crossover frequency.
General rules:
The larger the array the more directional it becomes
A larger, directional system will be less affected by the room
We get a 6dB far field sound pressure boost every time we double the
number of cabinets.
Stacking safety!
Stacked WLX or WLXGS subwoofers should always be blocked, strapped
and anchored from above by a qualified rigger.
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Coverage angle for tightly packed flat fronted arrays
-6dB Coverage
Here is a simplified formula for calculating the main coverage angle of a tightly packed flat fronted array.
* = approximate speed of sound in m/s. Varies with temperature (see Section 2a).
Arcsin means “the angle whose sin is ...”
Flat fronted cluster coverage patterns will be confined to one main lobe whose mid-bass crossover directivity
is proportional to the size of the cluster.
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The medium sized array (left) has significant output to ±90º whereas the large array’s ±90º output is
dramatically reduced.
A note on coverage nulls
It is useful to be able to calculate where these first response nulls will occur for various frequencies as they
indicate areas where coverage, transient response and directional information would be poor without fill
systems. For symmetrical arrays nulls will occur either side of the on-axis line. We can calculate the overall
“null-to-null” angle using the simple formula:
As a very rough guide, the null-to-null angle will be approximately twice the -6dB coverage angle.
Interpreting polar plots
i) It is conventional to “normalise” polar plot on-axis amplitudes so that different polar shapes may be readily compared. In
practice, the large array (right example) would have a higher on-axis amplitude than the medium array.
ii) It is also conventional to plot polar amplitudes on a logarithmic scale. This is fine when working in sound pressure level terms
but is not suitable for superimposing a polar plot onto a venue plan. Venue plans are drawn to a linear scale so polar plots with
linear amplitude scales would be more suitable.
iii) Polar plots have been simplified in this article for clarity. Real-world off-axis lobe amplitudes and shapes would vary
considerably depending on boundary loading, echoes, reverberation and other audio sources affecting the same space.
Vertical -6dB coverage
The following table gives the approximate vertical coverage angles of typical WLX/WLXGS arrays -
ignoring boundary effects (see later).
WLX/WLXGS High Vertical coverage
47Hz 94Hz 188Hz
3 Wide Wide 98º
4 Wide Wide 69º
8 Wide 69º 33º
16 69º 33º 16º
Use tall stacks for long shots. Useful for long distances in low-roofed venues with raked seating up
to the height of the stack.
Use short stacks for short, wide vertical shots.
Use tall, electronically steered, stacks to project to high, distant seating – see later.
Vertical Boundary effects
As mentioned before, a solid floor will act as a reflector. This will cause a vertical stack to perform as if it
were double the length, giving a useful low frequency boost and a narrower vertical polar response.
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For instance, an 8 high ground-based stack of WLX/WLXGS subwoofers will act like the top half of a 16
high stack.
It is possible to reach higher seating areas whilst retaining a tall vertical stack by electronically “tilting” the
system - see later.
Note that flexible floors may actually absorb sound at some frequencies so the situation isn’t always so
simple in practice.
Horizontal - 6dB coverage
The following table gives the approximate horizontal coverage angles of typical WLX/WLXGS arrays -
ignoring boundary effects.
WLX/WLXGS Wide Horizontal coverage
43Hz 86Hz 172Hz
2 Wide Wide 75º
4 Wide 75º 35º
8 75º 35º 17º
16 35º 17º 9º
Use wide arrays for long shots. Useful for long, narrow venues
Use narrow arrays for short, wide shots
Horizontal Boundary effects
A solid wall near an array will act as a reflector. This will cause a horizontal array to perform as if it were
twice as wide, giving a useful low frequency boost accompanied by a narrower, more complex polar
response.
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Again, a flexible side wall may absorb sound at certain low frequencies. Boundaries should always be treated
with caution.
Spacing
It is possible to space out WLX or WLXGS subwoofers to provide a larger frontal area with fewer units but
care must be taken to avoid irregular coverage at higher, mid-bass frequencies.
The following formula gives the pressure ratio p(h) (wrt to the on-axis pressure) for any off-axis angle of a
regularly spaced linear array:
All material © 2007. Martin Audio Ltd. Subject to change without notice.