CONTENTS SCENARIO 1 INTRODUCTION UNPACKING VISUAL INSPECTION SPECIFIC POINTS 3 3 3 3 IMPORTANT SAFETY INSTRUCTIONS 6 POWERING 7 TECHNICAL SPECIFICATION 8 EQUALISATION CURVES 12 CONNECTOR PANEL CONNECTIONS 13 14 MODULE LAYOUT AND FUNCTIONS MIC/LINE INPUT MODULE MONO LINE INPUT MODULE STEREO LINE INPUT MODULE OUTPUT MODULE ADJUSTMENTS AND CALIBRATIONS 26 MONITOR MODULE 16 20 22 24 28 M-S NOTES 31 AD100-09 POWER SUPPLY UNIT 34 CUSTOMER NOTES AND FACTORY MODIFICATIONS 35 TECHNICAL LIBRARY
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.
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' Blumlein. tribute to, and celebration of the genius of Alan 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.
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.
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.
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.
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.
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.
TECHNICAL SPECIFICATION - ELECTRICAL REFERENCE MAX GAIN 0dB = 775mV at 1kHz unless otherwise stated 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 >1k5R >10kR >100kR 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 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. A B 6 I/P 350 325 8 I/P 411 386 10 I/P 472 447 12 I/P 533 508 DIMENSIONS IN MILLIMETRES WEIGHT 6 I/P 8.2 8 I/P 9.7 10 I/P 11.2 12 I/P 12.
SIZE DROP THROUGH VERSION OF MOUNTING A B C 6 I/P 318 324 369 8 I/P 379 385 430 10 I/P 440 446 491 12 I/P 501 507 552 MEASUREMENTS IN MILLIMETRES WEIGHT AS PREVIOUS 11
EQUALISATION CURVES 12
CONNECTOR PANEL (9) (10) (11) (12) (5) (6) (5) (3) (4) (1) (2) (1) Microphone input or Line 1 of mono input or Left of stereo input (2) Line input or Line 2 of mono input or Right of stereo input (3) Main A-B outputs (4) Main C-D outputs (5) Monitor 1 Left-Right outputs (6) Return 1 Left-Right jack sockets (7) Return 2 Left-Right jack sockets (8) Monitor 2 output jack socket (9) Talk send & return (10) Subsidiary connector (11) External DC power input (12) Off/On switch (external & internal) 13
All input and output SPECIFICATION. impedances are to be found in the TECHNICAL All inputs to, and outputs from AD146 are to be found on the connector panel.
External powering of the mixer is via a 4-pin XLR (13). XLR Pin 1 Pin 2 0V Charge Pin 3 Pin 4 15V - 24V DC 12V - 15V DC A suitable external power supply is Audio Developments’ AD100-09, but any external DC source must be capable of delivering 750mA at 12V. Note - When the chassis size exceeds 12 inputs, or when specified by the customer, a 5 pin XLR (13) is fitted to accept external powering. The internal DC-DC Converter is omitted. A suitable external power supply is Audio Developments AD 100-10.
MICROPHONE/LINE MODULE (1) Phantom-power toggle (2) Phase-change toggle (3) Input-gain selector (12) Line-input toggle (4) High-frequency amplitude control (13) High-pass filter (5) Mid-frequency amplitude control (14) EQ selector (6) Low-frequency amplitude control (15) Matrix selector (7) Panoramic potentiometer (8) Individual routeing to A,B,C,D outputs (16) Routeing to monitor 1 (9) Pre-fader listen (10) PFL indicator LED (11) Overload LED (17) Channel fader 16
The transformer-balanced, ultra-low-noise microphone 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 signal-to-noise performance as the gain is reduced. (The rotary switch may be replaced with a potentiometer for continuously-variable gain control.
S-switch (15) - creates a matrix amplifier across an adjacent pair of input modules. Refer to M-S NOTES. The panoramic potentiometer (7) routes the signal proportionately between A and/or C outputs (L) and B and/or D outputs (R). Routeing switches (8) 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 (15) if selected.
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MONO LINE MODULE (1) Input selector toggle (2) Phase-change toggle (3) Input-gain control (4) High-frequency amplitude control (5) Mid-frequency amplitude control (12) EQ selector (6) Low-frequency amplitude control (13) Matrix selector (7) Panoramic potentiometer (8) Individual routeing to A, B, C, D outputs (9) Pre-fader listenPFL indicator LED (10) (14) Routeing to monitor 1 (11) Overload LED (15) Channel fader 20
For optimum performance at line level, this module employs a double-balanced, instrumentation-grade input amplifier (3 x ICs) rather than the inferior differentiallybalanced amplifier (1 x IC). Isolation between inputs (Line 1 and Line 2) is so high, they may remain connected to the mixer simultaneously. Line 2 input is selected by switch (1). Phase change (2) precedes the radio-frequency, interference-suppression circuitry. Input gain is switched in 2dB steps allowing up to 10dB of gain or attenuation (3).
STEREO LINE MODULE (1) Input-changeover toggle (2) Phase-change toggle (3) Input-balance control (4) High-frequency amplitude (5) Mid-frequency amplitude control (6) Low-frequency amplitude (13) EQ selector (14) Matrix selector (7) Width control (8) L, R, A/B, C/D routeing switch (9) Pre-fader listen (10) PFL indicator LED (11) Overload LED - left (12) Overload LED - right (15) Routeing to monitor 1 (16) Channel fader 22
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).
(NOTE: It should be realised that a pair of mono input modules will always be more flexible and versatile than a stereo module.
OUTPUT MODULE (10) Mixer ON LED (11) Battery indicator (1) Meter 1 (12) A or C to meter 1 (13) Mon left to meter 1 (14) Meter illumination (15) B or D to meter 2 (2) Meter 2 (16) Mon right to meter 2 (17) 1kHz or 10kHz line-up (18) Continuous or interrupted line-up tone (19) Matrix across C & D (20) Line-up tone to C & D (21) Limiter in C & D (22) Limiter link of C & D (23) Limiter indicator LEDs (3) Line-up tone to A & B (4) Matrix across A & B (5) Limiter link of A & (6) Limiter in A & (7) Limiter i
The meters are to broadcast specification with switchable functions; PPM and VU movements are available to choice. The upper meter (1) reads battery status BATT (11), A and C output levels and monitor 1 left-output level. The lower meter (2) reads B and D output levels and monitor 1 right-output level. The monitor 1 signal will be the one (or mix) selected on the monitor module. LED (10) illuminates when the mixer is switched ON.
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.
MONITOR MODULE (1) Channels to monitor (2) A output to monitor (3) B output to monitor (4) A-B output to monitor (5) C output to monitor (6) D output to monitor (7) C-D output to monitor (8) Stereo-return 1 to monitor (9) Stereo-return 2 to (10) Monitor 1 left output-level control (11) Monitor 1 right output-level control (12) Monitor 1 output (13) Matrix selector & indicator (14) Mono of monitor outputs & indicator (15) Monitor 2 right output-level control (16) Reverse talkback & PFL level control (20) In
The monitor module is associated with all aural monitoring of input and output signals together with communications between the sound operator and an outstation. It is necessary to be able to audition (in left-right stereo, ie a form the human brain understands), an X-Y (A-B) stereo microphone and an M-S stereo microphone whether the channel panpots are set centrally or hard left and hard right (thus creating conflicting monitor requirements).
has been matrixed to the L-R domain by DEC (13). Any signal in the L-R domain may be matrixed (13) in order to reveal mono capability on monitor 1 left and out-of-phase components on monitor 1 right. These signals may be isolated by selective use of level controls (10) & (11) and MONO (14). Refer to M-S NOTES. Operating on monitor 1 output is the dim control (12) which dims the output by 20dB. This dim function is automatic when the internal microphone (20) is routed to A/B (18) and/or C/D (19).
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.
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 ithe L-R domain. For example, the M-microphone will be placed in the optimum position for a mono image, whereas mixing to mono the signals from an X-Y stereo pair introduces phase anomalies.
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. With CH (1) selected on the monitor module, MON on an M-channel will audition the microphone on monitor 1 left but use of MONO (14) will place the signal on both outputs of monitor 1. Similarly, MON on an S-channel will audition that microphone on monitor 1 right.
POWER SUPPLY UNIT TYPE AD100-09 The AD100-09 mains POWER SUPPLY UNIT is suitable for driving most of AUDIO DEVELOPMENTS’ range of portable audio mixers. This PSU is a single-rail device providing 500mA of current at +14v DC potential and is used as a substitute for battery power with mixers containing an internal DC-DC converter. The AD100-09 may be powered from either a 110/120v AC source or a 220v/240v AC source.
It is DANGEROUS to change the specification or modify the product in any way.
TECHNICAL LIBRARY 37
