CONTENTS
SCENARIO 1
INTRODUCTION 3
UNPACKING 3
VISUAL INSPECTION 3
SPECIFIC POINTS 3
IMPORTANT SAFETY INSTRUCTIONS 6
POWERING 7
TECHNICAL SPECIFICATION 8
EQUALISATION CURVES 12
CONNECTOR PANEL 13
CONNECTIONS 14
MODULE LAYOUT AND FUNCTIONS
MIC/LINE INPUT MODULE 16
MONO LINE INPUT MODULE 20
STEREO LINE INPUT MODULE 22
OUTPUT MODULE 24
ADJUSTMENTS AND CALIBRATIONS
26
MONITOR MODULE 28
M-S NOTES 31
AD100-09 POWER SUPPLY UNIT 34
CUSTOMER NOTES AND FACTORY MODIFICATIONS 35
TECHNICAL LIBRARY 36
0
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 sub-set 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.
1
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.
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.
2
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 back cover, adjacent to the battery
compartment.
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
Battery compartment - the mixer has an integral battery compartment to accept 10
size-C cells, and is formed as part of the bottom transversal extrusion. This helps to
lower the centre of gravity, as well as adding to the rigidity of the frame.
DC-DC converter - is mounted on the top side of the battery housing and is
underneath the fader section of the output and last four input modules.
In order to facilitate the testing and calibration of all modules, a set of two extender
modules is available from the factory.
3
Fuses - to protect the mixer and internal power supply are mounted on the power
supply/converter board. Access is gained by removing the output module. 20mm, 1A
ANTI-SURGE HRC fuses are used - one for the internal battery power supply and one
for the external DC supply.
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.
Reverse-talkback output - is set at the factory to provide a mono mix of monitor 1 left
and right outputs, rather than mute, when the main talkback switch is released. This
function can be disabled by the DIL switch to be found on the left-hand PCB of the
monitor module.
Line-up tone - at 1kHz and 10kHz is calibrated on the meters to PPM4, giving a line
output level of 0dBu with L/R and AUX 1/2 controls 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.
4
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 - 48v phantom or 12v tonader - may be
selected before or after the microphone is connected to the module.
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.
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.
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 audiotoys 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 01543 375351 or by fax on 01543 361051.
5
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 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.
6
POWERING
The mixer may be powered from either internal cells or an external DC power source.
The integral battery compartment requires a total of 10 size-C cells. Access is gained
via a captive lid which is retained by two, 90-degree-turn buckles. The lid hinges
outwards 45 degrees from the back panel. When installing new cells, the row
nearest the hinge should be fitted first.
Either conventional dry, or rechargeable nickel-cadmium cells may be used. NICADs
may be recharged in situ through the 4-pin POWER IN connector. (The circuit for
recharging is already incorporated within the mixer.) A voltage in the range +15V to
+24V DC @ 250mA is required on PIN 2 of the POWER IN XLR.
When driving the mixer from an external power source, PIN 1 is the 0v connection
and a voltage in the range +12V to +15V DC should be supplied to PIN 4. The power
source should be capable of delivering approximately 400mA - allowing some
capacity for phantom powering.
If an external power supply unit (PSU) is to drive the mixer and simultaneously charge
a set of NICADs, a current capability of at least 650mA is required. It is poor practice
to run a PSU at its limit, therefore we recommend a minimum of 750mA.
Audio Developments AD100-09 PSU is a suitable unit.
WARNING: When NOT using the PSU (AD100-09) supplied for the mixer, ensure
your 4-pin XLR is correctly wired to match the POWER IN connector. Failure to do
so may result in the breakdown of the internal DC-DC converter. Make this check
even if using a PSU which may have been supplied to you in the past, eg AD100-06.
AD100-05 PSU is NOT suitable for use with an AD146 mixer and must not be used.
7
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 LEVELMIC -42 -32 -22 -12 -2 +8 dB
LINE -7 +3 +13 +23 +33 +43 dB
RETURNS +24 dB
INPUT MIC >1k5R
IMPEDANCE LINE >10kR
RETURNS >100kR
MIC POWERING +48V DC and +12V DC PHANTOM POWER
+12V TONADER (to order)
MAX OUTPUT +23.5dBm (600R LOAD) - A,B,C,D;TRANSFORMER BALANCED
CLEAN FEED/CHANNEL OUT; ELECTRONICALLY BALANCED
+18dBm (600R LOAD) - MON 1 L&R; XLR
MON 2; UNBALANCED STEREO JACK
OUTPUT <60R A,B,C,D; CLEAN FEED/CH OUT
IMPEDANCE <20R MON 1; MON 2 (HEADPHONES JACK)
FREQUENCY +0; -1dB 20Hz to 20kHz MAIN SIGNAL PATHS
RESPONSE +0; -1.5dB 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 FILTER -3dB @ 90Hz and 150Hz, 12dB/OCTAVE SLOPE
HARMONIC <0.03% @ 1kHz 0dBm OUTPUT
DISTORTION <0.15% @ 40Hz to 20kHz +15dBm OUTPUT
CROSSTALK <-70dB 40Hz to15kHz INTERCHANNEL & INTERGROUP
<-55dB 40Hz to15kHz BETWEEN L&R ON STEREO CHANNEL
8
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 AD100-09 POWER SUPPLY UNIT
+14V DC, 4-PIN XLR
3W (WITHOUT MICROPHONE POWERING)
9
TECHNICAL SPECIFICATION - MECHANICAL
AD146 is supplied with 6, 8, 10 or 12 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 monitor outputs.
WEIGHT
6 I/P 8 I/P 10 I/P 12 I/P
A 350 411 472 533
B 325 386 447 508
DIMENSIONS IN MILLIMETRES
6 I/P 8 I/P 10 I/P 12 I/P
8.2 9.7 11.2 12.7
WEIGHTS IN KILOGRAMS
10
SIZE
A
DROP THROUGH VERSION OF MOUNTING
B 324 385 446 507
C 369 430 491 552
MEASUREMENTS IN MILLIMETRES
WEIGHT AS PREVIOUS
6 I/P 8 I/P 10 I/P 12 I/P
318 379 440 501
11
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