AD256 is another addition to the Audio Developments Ltd range of portable mixers, having comprehensive facilities set out in an ergonomically friendly design and all contained within a robust and rugged aluminium case with a relatively small footprint.
The features and specification are based on the well established AD255 Mixer. Input channel limiter, continuously variable HPF and mute switch are the main additions. As with the other models within the range, professional components are used throughout – including Penny and Giles 100mm, long-stroke, conductive plastics faders.
Location sound professionals now require multi-track record facilities; the channel direct outputs provide the necessary features. By use of an additional switch these outputs can source other signals if the direct signal is not required, (Main Output and Auxiliaries). This without compromising the simplicity of operation and reliability as with its counterpart the AD255..
Low noise microphone amplifier with powering for 48V Phantom and 12V Tonader (TA) powering.
6 to 12 input frame, mic or line selection.
A simple, but effective, three band equaliser, proved and approved under field conditions, in use throughout the AD140 Series of mixers.
Inputs are balanced and protected against radio-frequency interference. A continuously variable high-pass-filter protects against low-frequency saturation.
The main stereo output is transformer balanced and has separate left and right fader control.
Two auxiliary outputs are transformer balanced and have separate master rotary controls. Auxiliary 1 & 2 are routed from each input using a 3 position switch (off, pre & post fader). Auxiliary 2 has a rotary level control on each input.
A mono output of the left and right signals is also transformer balanced.
Direct outputs from each input channel are unbalanced using a very low output impedance drive amplifier enabling high drive capability and minimising line interference.
Limiters are incorporated on both the inputs and outputs. The main output limiter can be linked for stereo operation. LEDs indicate limiting action.
Two LCD meters display – either PPM or VU – main output, auxiliary output and PFL levels of each input. Useful for monitoring level at a direct output. Battery level and monitor status (Direct or Return) are also indicated. Back-light illumination is also included.
Internal oscillator at either 1kHz or 10kHz frequency. The oscillator signal replaces the signal on the output when selected.
An internal microphone enables the mixer operator to communicate with the main output (SLATE), with each auxiliary and an external outstation (EXT). The outstation (Private Line) receives a monitor signal, selected using a series of push-button switches.
The headphone monitor may be switched between main output, auxiliary outputs and returns. PFL overrides the selected monitor signal. Monitor selection allows left, right, left/right, auxiliary 1, auxiliary 2, auxiliary 1 + 2 and returns to be routed to the headphone output. An M-S matrix amplifier can be inserted to main or auxiliary outputs in the M-S domain.
An electronically balanced stereo tape return appears on a pair of jack sockets on the connector panel.
All inputs and outputs are presented on one surface of the case. The inputs, main output and direct outputs are on XLRs. Auxiliary outputs, returns and headphone output are on ¼ inch jack sockets.
The mixer can be powered from an internally fitted battery box (8 x C cells) or an external DC source (12V to 15V DC)
REFERENCE 0dB=775mV at 1kHz unless otherwise stated.
MAX GAIN MIC 80dB
MAX INPUT LEVEL MIC @ MAX GAIN 44dB @ MIN GAIN + 6dB
LINE @ MAX GAIN -14dB
@ MIN GAIN +20dB
TB RETURN +18dB
INPUT IMPEDANCE MIC >2k5R
TB RETURN >20kR
MIC POWERING 48v PHANTOM & 12v TONADER
MAX OUTPUT +23dBm L-R TRANSFORMER BAL MONO TRANSFORMER BAL (600R LOAD)
+18dBm DIRECT OUT UNBALANCED
H’PHONE UNBALANCED (600R LOAD)
TB SEND UNBALANCED (600R LOAD)
<60R L-R & MONO
<20R DIRECT OUT & MONITOR
<20R TB SEND
0: -1dB L-R & MONO
0: -1.5dB MONITOR PATHS
<0.05% @ 1kHz @0dBm OUTPUT
<0.15% @ 40Hz to 15kHz @ +15dBm OUTPUT
OVERLOAD INDICATOR ILLUMINATES @ +15dBu at the PRE-FADER POINT
CROSSTALK <-70dB 40Hz to 15kHz
INTERGROUP & INTERCHANNEL
<-126dB EIN 20Hz to 20kHz; 200R SOURCE
LINE <77dB SNR 20Hz to 20kHz 0dBu IN & OUT
EQUALISATION HF: ±10dB @ 10kHz
LF: ±10dB @ 100Hz
CENTRE FREQUENCY 2k5Hz Q=1.2
HPF: 20-200 Hz VARIABLE 12dB/OCTAVE
ATTACK 2 SETTINGS INTERNALLY SWITCHABLE
1: 4mS 2: 0.8mS
RELEASE 2 SETTINGS INTERNALLY SWITCHABLE
1: 250mS 2: 80mS
FACTORY SETTING: SLOW
CURRENT CONSUMPTION 220mA (6 INPUT)
12V DC SUPPLY