Block Diagram - Martin Audio MLA User Manual

MLA System
U-Net connections are made using Cat5 cables fitted with 8-way push pull latching connectors compatible with ODU Series K.
Robust Cat 5 cable should be used such as Neutrik Etherflex or Belden 1305A, this will ensure reliable network connections of up
to 125 metres between network ports. U-Net protocol uses a redundant ring fault tolerance so connections "daisy-
chain"between all units in the network going from port 1 on the first unit to port 2 on the next and so on before finally making a
return connection back to port 2 on the first unit to complete the loop. The U-Net network will operate perfectly well without a
closed loop but it is strongly recommended to use this option so that the network will continue to work in the event of a break
in cable or disconnected connector.
Ready-made tour-grade network cables in a variety of lengths from short inter-cabinet patching to long front of house to stage
are supplied as part of an MLA system.
Analogue inputs should be connected with a good quality 3-pin Male XLR wired to good quality twin screened cable, this is
particularly important if the feed is a long length of cable; from front of house to stage for example. Good quality cable will
minimise losses over the cable run. The link outputs should use a similarly high quality Female XLR. Wiring is the industry standard
for balanced connections;-
Pin 1. Ground or shield
Pin 2 +, Hot, in phase
Pin 3 -, Cold, out of phase.
The signal source used to feed the MLA array must have line drive capabilities suitable for driving the combined load of the entire
array.
AES/EBU output connections are identical to analogue but cable used must be a dedicated 110Ω, low capacitance digital cable
such as Belden 1800F or 1696A.

Block Diagram

The MLA features sophisticated processing which feeds an amplifier for the low frequency and individual amplifiers for each mid
and high frequency drivers. The diagram below shows the signal path from the input which may be derived from analogue,
AES/EBU digital, or digital from the U-Net network, through to the drivers. All signal routing and monitoring is done via VU-Net
The input signal is first selected between back panel (the 3-pin XLR) or U-Net. If 'Back Panel' is selected there is then a further
choice of either analogue, AES Left or AES Right (as AES/EBU is a stereo feed). If U-Net is selected you may then select from any
of the four inputs or ten outputs from the Merlin controller which is supporting the network. A VU Meter displays the input level
prior to any internal processing, useful as an indicator of inappropriate levels from the signal source feeding the system.
There are then 10 bands of parametric EQ, a high pass filter and a gain control that are accessible for user adjustment of the
response. The array can be divided into up to six zones so that different EQ can be applied to different areas of the system.
Each band of parametric may be Peak, 2
0.4 up to 126 and gain may be adjusted between +15dB and -30dB.
The high pass filter can be either a Butterworth at 6, 12, 18, 24 or 48dB/Octave, Bessel at 12 or 18 dB/Octave or Linkwitz Riley at
either 12, 18, 24 or 48dB/Octave. Frequency is adjustable from 10Hz to 300. Finally gain may be adjusted from +15dB to -40dB.
There is a post EQ VU meter for each of the zones to ensure that over-zealous EQ hasn't done anything too drastic to system
headroom.
The signal is then fed to each of the six cells where further parametric EQ, an IIR all pass filter, high and low pass filters, FIR filters,
delay, gain, phase and limiting. The parameters for this extensive processing are created using Display 2 and uploaded to the
system via the U-Net network.
Finally, each cell has an amplifier tailored to the requirements of the driver(s) being driven. This adds 38dB of gain. The output
of the amplifier is fed back to the limiter to provide the best possible protection to each drive unit.
There are temperature sensors checking the temperature of the DSP and each individual cell amplifier. Finally each cell output
is displayed on a VU Meter.
MLA System User Guide V2.1
USER GUIDE
nd order Low Shelf or 2 nd order High Shelf. Filter bandwidth may be adjusted from a Q of
32