CONTENTS SCENARIO 1 INTRODUCTION UNPACKING VISUAL INSPECTION SPECIFIC POINTS 3 3 3 3 IMPORTANT SAFETY INSTRUCTIONS 5 POWERING 6 TECHNICAL SPECIFICATION 8 EQUALISATION CURVES 11 BLOCK DIAGRAM 12 CONNECTOR PANEL CONNECTIONS 13 14 INPUT MODULE 16 OUTPUT MODULE 19 ADJUSTMENTS AND CALIBRATIONS 23 AD100-015 POWER SUPPLY UNIT 25 CUSTOMER NOTES AND FACTORY MODIFICATIONS 26 TECHNICAL LIBRARY 27
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 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.
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. Output Limiter threshold - is set at the factory at +8dBu, but an internal preset potentiometer allows adjustment to any other level above 0dBu. The limiters are to be found on the output module printed circuit board.
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.
POWERING The mixer may be powered from either internal cells or an external DC power source. The integral battery compartment requires a total of 8 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.
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TECHNICAL SPECIFICATION - ELECTRICAL REFERENCE 0dB=775mV at 1kHz unless otherwise stated.
EQUALISATION HF: ±10dB @ 10kHz LF: ±10dB @ 100Hz MF: ±15dB CENTRE FREQUENCY 2k5Hz Q=1.2 HPF: SWITCHED PRE-TRANSFORMER -3dB @ 70Hz VARIABLE POST-TRANSFORMER 20Hz to 250HZ INPUT LIMITER THRESHOLD +10dB FADERS AT CAL POINT FACTORY SETTING:ATTACK 2mS RELEASE 200mS OUTPUT LIMITER THRESHOLD +8dB RATIO 7:1 ATTACK 2 SETTINGS INTERNALLY SWITCHABLE 1: 4mS 2: 0.
TECHNICAL SPECIFICATION - MECHANICAL SIZE 6 I/P 320 295 A B 8 I/P 381 356 10 I/P 442 417 ALL DIMENSIONS IN MILLIMETRES WEIGHT 6 I/P 6 8 I/P 7 10 I/P 8 12 I/P 9 ALL WEIGHTS IN KILOGRAMS 10 12 I/P 503 478
EQUALISATION CURVES AD256 ANDAND LOW EQ ADHIGH 245 HIGH LOW EQ 20 15 10 5 dB 0 -5 -10 -15 -20 10 100 1000 10000 100000 FREQUENCY AD 245 MID EQ AND HPF AD255 MID EQ AND HPF 20 15 10 5 dB 0 -5 -10 -15 -20 10 100 1000 10000 FREQUENCY 11 100000
BLOCK DIAGRAM 12
CONNECTOR PANEL 13
All input and output impedances and levels are to be found in the TECHNICAL SPECIFICATION. All inputs to, and outputs from AD256 are to be found on the connector panel.
Module connector (4) accepts balanced microphones and balanced line-level inputs. XLR (input & output) Pin 1 Pin 2 Pin 3 Shield Signal + Signal - In the case of unbalanced line-inputs and outputs, pins 1 & 3 should be connected. This will not lead to a loss of level. Channel direct outputs (12) are at line level and unbalanced Main stereo (2), mono (1) and auxiliary outputs (10) are transformer balanced and are at line level. The auxiliary outputs appear on two ‘A’ type stereo jacks.
fed to the outstation. Selecting more than one source creates a mix of the chosen signals. A three-position rocker switch BATT/EXT (7) selects either internal batteries or an external DC source. Correct power to the mixer is confirmed by the BATT indicator on the lower LCD meter. The first bar of the indicator flashes when the internal voltage falls below the safe operating level of 9V. External powering of the mixer is via a 4-pin XLR (6).
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The Microphone/Line input module functions are as follows: Switch (12) selects 48V phantom and 12V tonader power for condenser microphones. Powering may be selected before or after connecting the microphone, but switch off all powering on unterminated modules to ensure unconditional stability of the mixer. For complete safety of external equipment, switch off microphone power before connecting a linelevel signal. Phase change (15) is pre transformer and operates on microphone and line inputs.
Auxiliary 1 is a fixed level and auxiliary 2 has a level control (6), which acts purely as an attenuator - when set at 10 and source post-fader the output tracks with, and is at the same level as the L/R outputs from the module. This also applies to the post-fader position of auxiliary 1. The unbalanced channel output is available on a XLR on the connector panel in line with the input connector. The level of the direct out signal is controlled by preset (3).
OUTPUT MODULE 20
This module controls the level of main and monitor output signals and metering of the output and monitor signals (including PFL). Calibration is achieved when the output faders (7) are at maximum. The two LCD meters read the various outputs and battery status. The upper meter (1) reads left and right outputs; the upper bar reading left output and the lower right output. The lower meter (2) reads the auxiliary outputs, channel output and battery status.
Line-up tone, when selected (11), replaces the normal signals on the main output. The frequency of the line-up tone may be selected between 1kHz and 10kHz (13). Line-up tone is calibrated on the (PPM-scaled) meters to ‘0’, giving a line-output level of 0dBu with the output faders set to maximum. The auxiliary output signal levels are controlled by two potentiometers (3). Separate Penny & Giles faders (7) are employed for maximum flexibility and control of the main left and right output signals.
Communications from external 1 outstation to the mixer operator is initiated at the outstation and feeds the PFL mix busses. This is achieved by grounding pin 6 of the 6 pin XLR. Like other PFL signals it is under logic control and replaces any other signal on the monitor output. When PFL is selected on an input channel or when the outstation wishes to communicate with the mixer operator (by grounding pin 6 on the multiway), logic changes the signal on monitor output accordingly.
ADJUSTMENTS AND CALIBRATIONS Meters - are to broadcast specification and either a VU or a PPM may be selected by an internal DIL switch mounted on each meter driver printed circuit board. Line-up-tone oscillator - the preset (VR6) that adjusts its level at the output of the mixer is mounted on the output module printed circuit board. Low-battery indicator - the preset (BATT) associated with this facility is also mounted on the meter module printed circuit board.
PPM or VU setting - A DIL switch controls this function and is shown on the above diagram. When the switch is in its off position the meter follows a PPM characteristic and in the on position a VU characteristic. Meter illumination - A DIL switch enables the intensity of the meter back-light to be altered. The factory setting is with the switch in the off position. It is recommended that this setting is retained, because the higher intensity setting obviously increases battery drain.
POWER SUPPLY UNIT TYPE AD100-015 The AD100-015 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 1A of current at +15V DC potential and is used as a substitute for battery power with mixers containing an internal DC-DC converter. The AD100-015 may be powered from either a 110/120V AC source or a 220V/240V AC source. Ensure that the AC voltage source is in the range 100V to 240V AC.
CUSTOMER NOTES AND FACTORY MODIFICATION 27
TECHNICAL LIBRARY 28
