CONTENTS SCENARIO 1 INTRODUCTION UNPACKING VISUAL INSPECTION SPECIFIC POINTS 3 3 3 3 IMPORTANT SAFETY INSTRUCTIONS 5 POWER SUPPLY UNIT 6 TECHNICAL SPECIFICATION 8 EQUALISATION CURVES 12 CONNECTOR PANEL CONNECTIONS 13 14 MODULE LAYOUT AND FUNCTIONS MICROPHONE/LINE INPUT MODULE STEREO LINE MODULE OUTPUT MODULE ADJUSTMENTS AND CALIBRATION MASTER MODULE MONITOR MODULE 16 20 22 24 26 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.
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.
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.
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.
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.
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).
DC OUTPUT XLR CONNECTIONS Pin 1 Pin 2 Pin 3 Pin 4 Pin 5 0V +12V DC -12V DC NO CONNECTION 0V NOTE: The power supply unit contains no user serviceable parts inside. Refer servicing to qualified service personnel.
TECHNICAL SPECIFICATION - ELECTRICAL REFERENCE 0dB = 775mV at 1kHz unless otherwise stated MAX GAIN MIC 85 LINE 50 75 40 65 30 55 20 45 10 35 0 dB dB MAX INPUT LEVEL MIC -42 LINE -7 RETURNS -32 +3 -22 +13 -12 +23 -2 +33 +8 +43 +24 dB dB dB INPUT IMPEDANCE MIC LINE RETURNS >1k5Ω >10kΩ >100kΩ MIC POWERING +48V DC and +12V DC PHANTOM POWER +12V TONADER (to order) MAX OUTPUT +23.
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) 9
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 12 I/P A B 598 562 14 I/P 659 623 16 I/P 18 I/P 720 684 781 745 DIMENSIONS IN MILLIMETRES WEIGHT 12 I/P 16.0 14 I/P 16 I/P 18.5 21.0 18 I/P 23.
SIZE DROP THROUGH VERSION OF MOUNTING A B C 12 I/P 562 568 613 14 I/P 623 630 674 16 I/P 684 690 735 18 I/P 745 751 796 MEASUREMENTS IN MILLIMETRES WEIGHT AS PREVIOUS 11
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 socke
All inputs to, and outputs from AD144 are to be found on the connector panel. Balanced inputs and outputs are on XLRs. XLR Pin 1 Shield Pin 2 Signal + Pin 3 Signal - In the case of an unbalanced line-input, pins 1 & 3 should be connected. Main (3) to (6), auxiliary (7) to (10) and master (11) & (12) outputs are transformer-balanced, and are at line-level. When driving unbalanced loads, the mixer outputs may be safely unbalanced by connecting pins 1 & 3. This will not lead to a loss of output level.
‘D’ connectors for METER BRIDGE and REMOTE START are as follows: CONN (20) METER BRIDGE IDC D PIN 1 2 3 4 5 6 7 CONN. STD D PIN Chassis 1 0V 9 0V 2 Output master left 10 +V Lamp 3 Output master right 11 Spare 4 IDC D PIN 8 9 10 11 12 13 14 15 CONN.
MICROPHONE/LINE MODULE (1) Phantom power toggle (2) Phase- change toggle (3) Input-gain selector (4) High-frequency amplitude (16) Line-input toggle (17) High-pass filter (5) Mid-frequency amplitude control (6) Low-frequency amplitude control (18) EQ selector (19) Aux 1 source selector (7) Auxiliary 1 level control (20) Aux 2 source selector (8) Auxiliary 2 level control (21) Aux 3 source selector (9) Auxiliary 3 level control (10) Auxiliary 4 level control (22) Aux 4 source selector (23) Matrix s
The discreet and discrete microphone amplifier is the one designed for AD146 and has been tried, tested and proved in the field and in the studio. The transformerbalanced, ultra-low-noise amplifier does not require an input attenuator as the available 50dB gain change is achieved with a 6-position rotary switch (3) acting on the feedback alone - in 10dB steps. This has the advantage of not degrading signalto-noise performance as the gain is reduced.
S-switch (23) creates a matrix amplifier across an adjacent pair of input modules. Refer to M-S NOTES. The panoramic potentiometer (11) routes the signal proportionately between A and/or C outputs (L) and B and/or D outputs (R). Routeing switches (12) are independent of each other and also act as channel mutes. The monitor 1 path is the true output from the module (independent of any other routeing) and is derived from the output of the panpot - and S-switch (23) if selected.
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STEREO LINE MODULE (1) Input-changeover toggle (2) Phase-change toggle (3) Input-balance control (4) High-frequency amplitude control (5) Mid-frequency amplitude (6) Low-frequency amplitude control (16) EQ selector (7) Auxiliary 1 level control (18) Aux 2 source selector (17) Aux 1 source selector (8) Auxiliary 2 level control (9) Auxiliary 3 level control (19) Aux 3 source selector (20) Aux 4 source selector (10) Auxiliary 4 level control (11) Width control (12) L, R, A/B, C/D routeing switch (13)
For optimum performance at line level, the stereo module employs RFI suppressed, double-balanced, instrumentation-grade input amplifiers. The input-changeover toggle (1) interchanges the inputs to connectors 1 & 2 without having to replug. The phase-change toggle (2) changes the phase of the signal on connector 2 and is unaffected by the position of toggle (1). The module's input stages have fixed, unity gain; nevertheless it is possible to rebalance the stereo input-signal with the OFFSET control (3).
OUTPUT MODULE (9)Mixer ON LED (10) Meter illumination switch (1) Meter 1 (11) A & B to meters (12) C & D to meters (13) Aux 1 & 2 to meters (14) Aux 3 & 4 to meters (2) Meter 2 (15) Monitor 1 to meters (16) 1kHz or 10kHz tone (17) Continuous or interrupted Line-up tone (3) Auxiliary output level (18) Matrix across C & D (4) Line-up tone to A & B (5) Matrix across A & B (19) Line-up tone to C & D (6) Limiter link of A & B (20) Limiter in C & D (7) Limiter in A & B (21) Limiter link of A & B (22)
The meters are to broadcast specification with switchable functions; PPM and VU movements are available to choice. The upper meter (1) reads A, C, AUX 1, AUX 3, MON 1 left outputs when selected on switches (11) to (15). Similarly, the lower meter (2) reads B, D, AUX 2, AUX 4, MON 1 right outputs when selected on switches (11) to (15). Only one of the switches (11) to (14) must be pressed at any one time - switch (15) will override the other switches.
ADJUSTMENTS AND CALIBRATIONS Refer to component location diagrams in TECHNICAL LIBRARY. Line-up-tone oscillator - the preset (VR1) that adjusts its level at the outputs of the mixer is mounted on the right-hand PCB of the output module and can be adjusted from the copper foil side of the board. Meters - either a VU or a PPM may be selected. A choice of 3 scales is available for the PPM: BBC, N10, SDR. VU meter - there is one preset, on the VU meter PCB, for meter adjustment.
Output limiters - calibration involves four presets per output; however, only two are involved with a particular parameter. Using 'A' output as the example… Biasing and threshold are adjusted as follows: VR104 biases the limiter circuit to the point of correct operation and VR103 sets the threshold. (Labelled SET 0 and TH respectively on the left-hand PCB.) With no signal present, VR104 should be adjusted to give a reading in the range -1.5V to -2.5V at PIN 12 of IC7.
MASTER MODULE (1) Line-up tone (18) Channel to Master L & R (2) Auxiliary 1 level (19) Aux 1 source selector (3) Auxiliary 2 level (20) Aux 2 source selector (4) Auxiliary 3 level (21) Aux 3 source selector (5) Auxiliary 4 level (6) Group A level to L & R (22) Aux 4 source selector (10) Pre-fade Listen A (23) Panoramic potentiometer A (7) Group B level to L & R (11) Pre-fade Listen B (24) Panoramic potentiometer B (8) Group C level to L & R (12) Pre-fade Listen C (25) Panoramic potentiometer C
The master module has two transformer balanced outputs which appear on XLRs. Signals from the main group outputs A, B, C & D and the input channels can be routed to the master left & right outputs. Auxiliary attenuators (2) to (5) and source switches (19) to (22) are identical with those of the mic/line modules. A mix of left and right signal paths is used to drive the auxiliary sends.
MASTER OUTPUT BLOCK 28
MONITOR MODULE (1) Auxiliary Return to Master (23) Auxiliary Return Level (2) Channel to Monitor 1 (24) Auxiliary 1 to Monitor 1 (3) A Output to Monitor 1 (25) Auxiliary 2 to Monitor 1 (4) B Output to Monitor 1 (26) Auxiliary 3 to Monitor 1 (5) A.B Output to Monitor 1 (27) Auxiliary 4 to Monitor 1 (6) C Output to Monitor 1 (28) Return 1 Left to Monitor 1 (7) D Output to Monitor 1 (29) Return 1 Right to Monitor 1 (8) C.
AD144 monitor facilities and functions are incorporated on a single module. It is split into two sections. The first section selects (and mixes) signals to monitor 1 and the second section selects (and mixes) signals to monitor 2. Monitor 1 output is transformer-balanced and appears on a pair of XLRs ( L & R). Monitor 2 output is intended to drive headphones via a standard ‘A’ type stereo jack – available on the connector panel and the bottom of the monitor module.
Monitor 2 output functions in a similar way to monitor 1 except when a channel PFL (pre-fader listen) switch is selected. In this case logic changes monitor 2 to read the appropriate channel – mono PFL from a mic/line module and stereo PFL from a stereo-line module. When PFL is released, monitor 2 reverts to signals derived using monitor 2 select functions. PFL has a separate level control (36) to balance the signal against other signals presented to monitor 2 outputs. Main outputs A to D and L.
Monitor 2 Output is on an ‘A’ type stereo jack (22) for driving headphones. This is duplicated on the connector panel. It is recommended that the headphones used have an impedance of 600 ohms or greater. This will ensure the overall operation of the mixer remains within its optimum specification. An auxiliary return function, associated with the master output, is also present on this module.
MONITOR BLOCK DIAGRAM 33
M-S NOTES The M-S techniques proposed by Alan Blumlein in the early nineteen-thirties have recently been (re)discovered. These techniques fall into two parts: those used during original recordings, and those used in post-production. The way to change the width of the image from an X-Y stereo microphone (without physically moving it), or from an existing L-R recording, is to convert to the M-S domain in order that the M/S relationship can be altered.
matrix amplifier. For any L-R stereo signal appearing on the monitor modules, DEC (15) will reveal mono capability (M) on monitor 1 left module and out-of-phase components (S) on monitor 1 right module. These signals may be isolated by selective use of the monitor 1 output faders. Blumlein's microphone techniques have advantages over all others (X-Y and A-B) such that it is worthwhile using M-S microphones even when mixing is to be done in the L-R domain.
Spot microphones will be panned to their correct position in the final L-R image, and may be monitored as non-destructive solo-in-place or, if CH (1) is selected on only one monitor module, as true AFL. When mixing in the M-S domain (and) using M-S microphones, M-channels will be panned left, S-channels will be panned right and spot microphones will be panned left to mix with the M-channels only.
COMMUNICATIONS MODULE (1) Routes A & B to Comms 1 (2) Routes C & D to Comms 1 (3) Routes Aux 1 to Comms 1 (4) Routes Aux 2 to Comms 1 (5) Routes Aux 3 to Comms 1 (19) Talk or Return to Comms (6) Routes Aux 4 to Comms 1 (20) Comms 1 output-level control (7) Insert M-S Matrix into Comms 1 (21) Talk or Return to Comms (8) Routes CH Monitor to Comms 1 (9) Monitor Select to Comms 2 (10 Monitor Select to Comms 3 (Mono of Comms or Monitor) (23) Comms 3 output-level control (11) Comms return level (24) Tal
BLOCK DIAGRAM 38
This section should be read in conjunction with Pt 3 of the BLOCK DIAGRAM together with the following diagrams. The comprehensive communications module must be fitted in the last position of the mixer frame. This module enables aural contact between the sound-operator and three outstations together with the routeing of signals from the mixer for monitoring at the outstations - boom-man, director, producer etc.
The mono signal to COMM 2 is selected by an 11-way rotary switch (9) - posn 1 is a mono mix of the signal to COMM 1; posn 2 is a mono mix of the signal appearing on the monitor modules; posn 3 is a mono mix of the signals selected by MON on the channel modules; the remaining positions select the 4 output signals and the 4 auxiliary signals. Output level is controlled by potentiometer (22).
To operate the majority of external devices, it will be necessary to ‘close’ a circuit, but, for some, it will be necessary to ‘open’ the control circuit. The relays are situated at the top of the module’s printed circuit board, and associated with each one is a DIL switch that enables it to close a circuit (normally open - N/O) or open a circuit (normally closed - N/C). The module leaves the factory with switches in the N/O position.
42
DIL Switch settings Right-hand printed circuit 43
CUSTOMER NOTES AND FACTORY MODIFICATION 44
TECHNICAL LIBRARY 45
