AD255 is the latest 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 AD245 Pico Mixer. Two auxiliary sends and channel direct outputs are the main additional features. 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; without compromising the simplicity of operation and reliability of its counterpart the AD245.

Low noise microphone amplifier developed for AD140 series of mixers. Power is provided for 48V Phantom and 12V Tonader microphones

A simple but effective three band equaliser, proved and approved under field conditions, in use throughout the AD140 series of mixers

Inputs are transformer balanced and protected against radio-frequency interference. A high-pass filter protects against low-frequency saturation.

The main stereo output is transformer balanced and has separate left and right faders

.

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 and post fader). Auxiliary 2 has a rotary level control

Limiters, which may be linked for stereo operation, are incorporated in the main output. Limiting is indicated by a pair of LEDs .

Direct outputs are unbalanced and driven from a very low impedance source with high drive capability.

Two LCD meters display - either PPM or VU - monitor the main output, auxiliary output and PFL of each input. Useful for monitoring level at a direct output. Battery level and monitor status (Direct or Return) are also indicated. Meters can be illuminated.

The frequency of the internal oscillator can be selected between 1KHz and 10KHz, it's output replacing the signal on the main output.

Via an internal microphone, the mixer operator is able to communicate with the main output (SLATE) and with an outstation (EXT) . The outstation normally receives a mono of the mixers main output.

The headphone monitor may be switched between main output, auxiliary outputs and return. All have PFL override. Monitor selectors allow left , right, left + right, auxiliary 1, auxiliary 2 and auxiliary 1 + 2 to be routed to the headphone socket. An M-S matrix amplifier may be inserted in order to decode main or auxiliary outputs in the M-S domain.

An electronically balanced stereo tape return appears on a pair of stereo jack sockets. An input calibration potentiometer is adjacent to the jack sockets on the connector panel.

All input and output connectors are presented on one surface of the case and in line with their corresponding modules.

The mixer receives power from 8 x C cells fitted internally or from an external 12V - 15V DC source.

REFERENCE 0dB=775mV at 1kHz unless otherwise stated.

MAX GAIN MIC 80dB

LINE 50dB

MAX INPUT LEVEL MIC @ MAX GAIN -44dB @ MIN GAIN + 0dB

LINE @ MAX GAIN -14dB @ MIN GAIN+20dB

STEREO-RETURN +18dB

TB RETURN +18dB

INPUT IMPEDANCE MIC >2k5R

LINE >6k5R

STEREO-RETURN >100kR

TB RETURN >20kR

MIC POWERING 48V PHANTOM & 12V TONADER

MAX OUTPUT +23dBm L-R, AUX & MONO

(600R LOAD) TRANSFORMER BAL

+18dBm DIRECT OUT, H'PHONE & EXT 1

(600R LOAD) UNBALANCED

OUTPUT IMPEDANCE <60R L-R, AUX & MONO

<20R DIRECT OUT, MONITOR & EXT 1

FREQUENCY 0: -1dB L-R, AUX & MONO & DIRECT OUT

RESPONSE 0: -1.5dB MONITOR PATHS

HARMONIC <0.05% @ 1kHz @ 0dBm OUTPUT

DISTORTION <0.15% @ 40Hz to 15kHz @ +15dBm OUTPUT

OVERLOAD ILLUMINATES @ +15dBu at the PRE-FADER INDICATOR

CROSSTALK <-70dB 40Hz to 15kHz

INTERGROUP & INTERCHANNEL

NOISE MIC <-126dB EIN 20Hz to 20kHz; 200R SOURCE

LINE <77dB SNR 20Hz to 20kHz 0dBu IN & OUT

EQUALISATION HF: ±10dB @ 10kHz

LF: ±10dB @ 100Hz

MF: ±15dB

CENTRE FREQUENCY 2k5Hz Q=1.2

HPF: PRE-TRANSFORMER 12dB/OCTAVE

-3dB @ 150Hz

-3dB @ 90Hz

OUTPUT LIMITER THRESHOLD +8dB

RATIO 7:1

ATTACK 2 SETTINGS

INTERNALLY SWITCHABLE

1: 4mS 2: 0.8mS

RELEASE 2 SETTINGS

INTERNALLY SWITCHABLE

1: 250mS 2: 80mS

FACTORY SETTING: SLOW

CURRENT 240mA (6 INPUT)

CONSUMPTION 12V DC SUPPLY

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