CONTENTS
SCENARIO 1
INTRODUCTION 3
UNPACKING 3
VISUAL INSPECTION 3
SPECIFIC POINTS 3
IMPORTANT SAFETY INSTRUCTIONS 5
POWER SUPPLY UNIT 6
TECHNICAL SPECIFICATION 8
EQUALISATION CURVES 12
CONNECTOR PANEL 13
CONNECTIONS 14
MODULE LAYOUT AND FUNCTIONS
MICROPHONE/LINE INPUT MODULE 16
STEREO LINE MODULE 20
OUTPUT MODULE 22
ADJUSTMENTS AND CALIBRATION 24
MASTER MODULE 26
MONITOR MODULE 29
M-S NOTES 34
COMMUNICATIONS MODULE 37
CUSTOMER NOTES AND FACTORY MODIFICATIONS 44
TECHNICAL LIBRARY 45
SCENARIO
Time was when it became necessary to update the ubiquitous AD145 PICO mixer.
Our survey showed two main requirements: as well as Audio Developments' build and
audio qualities, narrower and shorter modules were required, and the simple but
effective equaliser from PICO had to be retained. By this time, 4-track recording
equipment had begun to trickle into the marketplace (Nagra D etc), so we decided to
give the new mixer four outputs. Because of the lower noise-floor of modern digital
recorders, the level of input signals may be reduced. We have taken advantage of this
fact and lowered the slope ratio of the limiters to 7:1. By so doing, not only is signal
distortion greatly reduced, but also the artefacts associated with limiters become
much less noticeable or objectionable. Also, sixty years after the event, sound
engineers have come to realise the potential of Blumlein's M-S techniques; to this
end, facilities have been incorporated to take advantage of these techniques. The
result is AD146 - a four-output mixer.
This was followed by AD148 - edit mixer. Based on AD146, two comprehensive left
and right monitor modules have been added for editing purposes. If a mic/line module
is included for commentary or voice-over purposes, its input-gain switch can be
changed to a potentiometer, and its gain structure changed to ensure consistent level
matching with a fixed, mechanical point of reference. Unfortunately, this way of
working does reduce headroom and also compromises a mixer's noise performance.
After AD146/AD148 it was back to the drawing board. Our customers were still
demanding a two-output mixer - as a true replacement for the PICO, and with the
PICO's simplicity. Despite past assurances to the contrary, T powering is still
required. And could we incorporate auxiliaries? And could we possibly bring it to
market at 'entry level'? We have, and we have and that's MERCURY (AD147).
AD149 completes the 140 series of mixers, and has a repertoire of party tricks not to
be found in any other mixer - not even for 'ready money'. The design team
took, as its starting point, our list of all the ideas and suggestions presented to us over
the past few years. Many of these requests came from film-sound recordists - a subset of recordists we have unintentionally neglected in the past.
Since the days of R & D for AD146, channel insert points suddenly became
de rigueur. It transpires that many sound engineers have experienced the power of
FLEX-EQ, our industrial-strength equaliser, and wish to be able to use it when making
original recordings.
Being latter-day converts, we have included circuitry to take full advantage of all
M-S techniques - even shuffling - in both production and post-production.
Comment [AH1]: Page: 1
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AD149 is Audio Developments' tribute to, and celebration of the genius of Alan Blumlein.
We appeal to all AD149 users to break with tradition and, just on this occasion, study
the manual to reveal all the mixer's secrets. THIS IS ESSENTIAL
Well - we HAD every intention that AD149 would complete the 140 series. We'd
reckoned, however, without the persistence - nay, insistence - of our customers for a
mains-operated version of the AD146 with four auxiliaries ... we've called it AD144.
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INTRODUCTION
Unpacking
If there are any signs of damage to the outside of the carton, please notify us or your
supplier immediately, regardless of the unit's apparent physical condition. This is in
case a claim has to be made at a later date because of previously undetected transit
damage. The packaging material should not be discarded until the mixer has been
acceptance tested and a suitable transit/storage case is available for secure, safe
storage.
Visual Inspection
Identification - please make a separate note of the serial number for your own capital
equipment records. Ensure that it agrees with the number on the invoice/packing
note. The serial number label is on the case exterior.
Configuration - check that the correct number and combination of input modules have
been installed. If, for any reason, you wish to change the positions of the modules, do
not do so until after completion of any acceptance tests. Any tests then made will be
to a known configuration and can be compared with our factory records.
Temperature - check the meter glasses for condensation. If the package has been in
transit during cold weather, leave the mixer for at least 12 hours to allow it to return to
normal room temperature. Any measurements or subjective tests then made, will be
to a known temperature reference.
Specific Points
Until the mixer has been acceptance tested we strongly recommend that modules are
not removed for adjustment. If adjustments are necessary, refer to the section on
adjustments and calibration. All customer functions are external, except the following.
Limiter threshold - is set at the factory at +8dBu (PPM 6), but an internal preset
potentiometer allows adjustment to any other level above 0dBu. The limiters are to be
found on the left-hand PCB of the output module. Presets are also available for
adjusting limiter attack and release times.
Line-up tone - at 1kHz and 10kHz is calibrated on the meters to PPM4, giving a line
output level of 0dBu with A, B, C, D faders set to maximum. NOTE - PPM4
refers to the mark on a BBC PPM Scale. Other meter scales have a different mark at
0dBu level. Alternative calibration levels are possible via the internal preset.
RH-output ident - as an alternative to continuous tone on all main outputs; B & D
outputs can be pulsed with tone for 3 seconds.
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Module fix screws - Hexagon head screws are used to fix the modules and back
cover. The size being 1.5mm HEX A/F with a 2.5M thread.
If it becomes necessary to remove modules or back cover it is strongly advised using
a good quality hexagonal head driver.
Use of a screwdriver, however desperate, is not recommended.
Microphone powering - the mixer will remain unconditionally stable if the powering on
unterminated input channels is switched off - this also improves the noise
performance and crosstalk. Powering - phantom (or 12v tonader) - may be selected
before or after the microphone is connected to the module.
Surfaces - every working surface is covered by a hard plastic membrane which is
printed on the reverse side. These surfaces may be cleaned by most solvents, and
without fear of the legends being erased.
Connectors - for convenience, the connector panel is labelled for reading from above.
All connectors are in line with their corresponding module.
Every input module is mechanically shielded against radio-frequency interference.
In order to facilitate the testing and calibration of all modules, a set of two extender
modules is available from the factory.
ABBREVIATIONS
PPM peak programme meter
VU volume unit
VR variable resistor
X-Y coincident stereo-microphone
A-B spaced-apart stereo-microphone
M-S middle-side; techniques and microphone described by A D Blumlein
PCB printed circuit board
HPF high-pass filter
Finally, may we draw your attention to our range of portable, battery-operated
audio-toys called PORT-A-FLEX (AD066) which will complement your new mixer.
No 1 - broadcast quality compressor/limiter. Nos 3, 7, 8, 10 - distribution amplifiers
for microphone- and line-level signals. No 13 - the aforementioned FLEX-EQ in its
portable guise.
We wish you many trouble-free hours of use from your mixer. As a company, we are
fully committed to BS EN ISO 9001. Should you have any problems or require any
further information on FLEX-EQ or the M-S microphone technique, please do not
hesitate to contact us on 01922 457007 or by fax on 01922 457008 or by e-mail
sales@audio.co.uk.
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WARNING
IMPORTANT SAFETY INSTRUCTIONS
The user of electrical products must be familiar with their potential dangers, and
fundamental precautions must always be taken. Please read the following text
carefully.
Power supply units manufactured or supplied by Audio Developments Ltd are not user
serviceable. There are no user-serviceable parts associated with any such power
supply unit.
THE OUTER COVERS MUST NOT BE REMOVED
Such a power supply unit is solely for use with audio mixers and sound processors -
hereafter called the equipment - manufactured by Audio Developments Ltd.
Always use a cord set accepted by a National Approved Body.
EARTHING/GROUNDING: When using an external power supply unit that is
connected to the mains supply to drive the mixer it must be CONNECTED TO
EARTH.
In certain types of malfunction or breakdown, earthing provides a path of least
resistance for electric current and considerably reduces the risk of electric shock.
DANGER: Incorrect connection of the equipment grounding/earthing conductor can
result in the risk of electric shock. Where possible obtain a pre-wired mains lead from
a reputable supplier with the correctly fitted mains connector for the type of mains
outlet in use; otherwise, one correctly wired and checked by a qualified electrical
engineer. If your mains lead is not suitable for the mains outlet, have the correct plug
fitted by qualified personnel.
The MAINS PLUG of this equipment is the primary disconnect device. Therefore, in
the final application, ensure it remains close to the equipment and easily accessible.
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MAINS POWER SUPPLY
Also refer to IMPORTANT SAFETY INSTRUCTIONS
XP plc Model No AEH45UM21
The mains POWER SUPPLY UNIT is suitable for driving an Audio Developments
AD144 Mixer. This power supply unit has two voltage rails: +12V DC and -12V DC,
capable of supplying a minimum of 1A per rail, power the audio electronics. (The
+48V DC rail, capable of supplying 300mA, is generated internally using a DC-DC
Converter and powers the phantom supply for condenser microphones).
NOTE: The AEH45UM21 power supply unit is designed to power mixers without an
internal battery facility - and therefore no DC-DC Converter exists to generate
the+12V & -12V supplies. If such facilities are available, a power supply unit which is
a single-rail device, must be used.
The AEH45UM21 may be powered from either a 110/120V AC source or a 220/240V
AC source. The power supply unit automatically recognises the different source
voltages. Operating the equipment at the wrong voltage could be hazardous.
For connecting the power supply unit to the mains, always use a suitable nationally
approved cord set. If such a set is unavailable, care must be taken to connect the
LIVE, NEUTRAL and EARTH pins of the power supply’s IEC mains connector to
the corresponding terminals associated with the AC source. This work must be
undertaken by a qualified engineer.
FOR SAFETY REASONS, AEH45UM21 POWER SUPPLY UNIT MUST BE
CONNECTED TO MAINS EARTH. Any maintenance to the power supply unit or its
mains cable assembly must be performed by a suitably qualified engineer.
FUSES: It is recommended that the mains power cord is fused.
250mA HRC TYPE T 240V AC
For continued safety the specified fuse link must be fitted in the mains fuse holder
when a replacement is required. Ensure it is of a type approved by a National
Approved Body.
Each DC supply rail is protected by its own fuse - fitted internally: refer to the
TECHNICAL LIBRARY. Only suitably qualified personnel must service the power
supply unit. If any fuse link fails it is strongly recommended the cause is traced.
Only genuine spare parts with identical specifications must be used.
It is DANGEROUS to change the specification or modify the product in any way.
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DC OUTPUT XLR CONNECTIONS
Pin 1 0V
Pin 2 +12V DC
Pin 3 -12V DC
Pin 4 NO CONNECTION
Pin 5 0V
NOTE: The power supply unit contains no user serviceable parts inside. Refer
servicing to qualified service personnel.
DO NOT REMOVE THE OUTER COVERS
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TECHNICAL SPECIFICATION - ELECTRICAL
REFERENCE 0dB = 775mV at 1kHz unless otherwise stated
MAX GAIN MIC 85 75 65 55 45 35 dB
LINE 50 40 30 20 10 0 dB
MAX INPUT LEVEL MIC -42 -32 -22 -12 -2 +8 dB
LINE -7 +3 +13 +23 +33 +43 dB
RETURNS +24 dB
INPUT MIC >1k5Ω
IMPEDANCE LINE >10kΩ
RETURNS >100kΩ
MIC POWERING +48V DC and +12V DC PHANTOM POWER
+12V TONADER (to order)
MAX OUTPUT +23.5dBm (600R LOAD) - A,B,C,D; MASTER, AUX 1,2,3,4:
TRANSFORMER BALANCED
CLEAN FEED/CHANNEL OUT; ELECTRONIC BALANCED
+18dBm (600R LOAD) - MON 1 L&R; MON 2 L&R; AUX 1,2,3,4:
TRANSFORMER BALANCED
MON 2: UNBALANCED STEREO JACK
OUTPUT <60R A,B,C,D; AUX1,2,3,4; MON 1; MON2; CLEAN FEED/CH
IMPEDANCE <20R MON 2 (HEADPHONES JACK)
FREQUENCY +0; -1.5dB 20Hz to 20kHz MAIN/AUXILIARY SIGNAL PATHS
RESPONSE +0; -1.8dB 20Hz to 20kHz MONITOR SIGNAL PATHS
EQUALISATION LF; SHELVING ±10dB @ 100Hz VARIABLE TURNOVER
MAX ±15dB @ 30 Hz
MF; PEAK/DIP ±15dB @ 2k8Hz Q = 1.2 RECIPROCAL
HF; SHELVING ±10dB @ 10kHz VARIABLE SLOPE
MAX ±15dB @ 30kHz
HIGH-PASS -3dB @ 90Hz and 150Hz, 12dB/OCTAVE SLOPE
FILTER
HARMONIC <0.03% @ 1kHz 0dBm OUTPUT
DISTORTION <0.15% @ 40Hz to 20kHz +15dBm OUTPUT
CROSSTALK >70dB 40Hz to 15kHZ INTERCHANNEL & INTERGROUP
>55dB 40Hz to 15kHz BETWEEN L&R ON STEREO CHANNEL
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NOISE MIC <126dB 20Hz to 20kHz 200R SOURCE
(WITH RESPECT TO THE INPUT)
LINE <70dB SIGNAL-TO-NOISE RATIO 20Hz to 20kHz
LIMITER THRESHOLD +8dB
RATIO 7 : 1
ATTACK 2ms (SET AT FACTORY)
(VARIABLE VIA INTERNAL PRESET)
RELEASE 250ms (SET AT FACTORY)
(VARIABLE VIA INTERNAL PRESET)
POWERING EXTERNAL POWER SUPPLY UNIT
±12V DC, 5-PIN XLR
7W (WITHOUT MICROPHONE POWERING)
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TECHNICAL SPECIFICATION - MECHANICAL
AD144 is supplied with 12, 14, 16 or 18 input modules. A separate meter bridge fitted
with 4 VU or PPM meters is supplied to read outputs A,B,C and D. The mixer's meters
can then be dedicated to auxiliary 1 & 2, auxiliary 3 & 4 and monitor 1/PFL outputs.
SIZE
WEIGHT
12 I/P 14
16 I/P 18 I/P
I/P
A 598 659 720 781
B 562 623 684 745
DIMENSIONS IN MILLIMETRES
12 I/P 14 I/P 16 I/P 18 I/P
16.0 18.5 21.0 23.5
WEIGHTS IN KILOGRAMS
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SIZE
A
DROP THROUGH VERSION OF MOUNTING
12 I/P 14 I/P 16 I/P 18 I/P
B 568 630 690 751
C 613 674 735 796
MEASUREMENTS IN MILLIMETRES
WEIGHT AS PREVIOUS
562 623 684 745
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EQUALISATION CURVES
12
CONNECTOR PANEL
Mic/Line Module
(1) Microphone input
(2) Line-Level input
Stereo Line Module
(1) Line input left
(2) Line input right
Outputs
(3) Main A output
(4) Main B output XLR
(5) Main C output XLR
(6) Main D output XLR
(7) Auxiliary 1 output XLR
(8) Auxiliary 2 output XLR
(9) Auxiliary 3 output XLR
(10) Auxiliary 4 output XLR
(11) Master
Left output XLR
(12) Master Right output XLR
Monitor outputs / inputs
(13) Monitor 1 Left output XLR
(14) Monitor 1 Right output XLR
(15) Monitor 2 output jack socket
(16) Return 1 Left jack socket
(17) Return 1 Right Jack socket
(18) Return 2 Left jack socket
(19) Return 2 right jack socket
(24) Auxiliary Return jack socket
Meter bridge connector
(20) Remote start / Subsidiary
connector
(21) External DC power input
(23) Off/On switch
All input and output impedances and levels are to be found in the TECHNICAL
SPECIFICATION.
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