Minimac 2 · Compact audio message repeater

Installation

The Minimac2 (model MMD-USB) is a compact digital audio message repeater in an 18 gauge cold rolled steel chassis, 6.5″ wide × 4.5″ deep × 1.2″ high, 2 lbs. It mounts on a wall or a table, with a rack mount option. With no moving parts, it suits automatic unattended operation, also in harsh environmental or mobile conditions.

• Find a space on the wall or table; for table top use, fit the included rubber feet. Leave about 6 inches in front of and above the unit for access to the controls and wiring.
• Mount the unit with its wiring at least 18″ away from the power supply or other equipment that generates electrical noise.
• Connect the audio inputs and outputs, then the control inputs and outputs.
• With the optional power supply, make sure a standard, non-switched electrical outlet is available.
• Connect and apply power, then test the unit’s operation.

Connections

• Power (2 terminal pluggable connector, 2 pos Euro): pin 1 12 VDC at 1 A, or 15 VDC at 900 mA for the 10 W model; pin 2 ground. Current is 1 A with the power amplifier, 250 mA without. The power pack is sold separately (12 VDC, 1 A, or 15 VDC, 0.9 A).
• Mic input (1/8″ mini jack): mono microphone input for recording messages, up to 1.5 kΩ impedance, compatible with most consumer grade low impedance microphones.
• Line input (RCA): mono, unbalanced line level analog input for recording messages, 10 kΩ; compatible with the unbalanced outputs of most tape decks, CD players and DAT players.
• The mic input and the line input cannot be used at the same time; disconnect the line input for the microphone to work properly.
• Line output (RCA): mono, unbalanced line level analog output for playing messages, up to +3 dB into 600 Ω, a standard level for most applications; compatible with the unbalanced inputs of most audio equipment.
• 8 Ω speaker output (2 terminal pluggable connector, 2 pos Euro): bridged amplifier output + (pin 1) and − (pin 2), 2.5 W into 8 Ω (10 W on the Minimac2/10W). Use it when more drive is needed to reach a comfortable listening level; the built-in amplifier drives a speaker directly without additional hardware.
• Never reference either speaker output terminal to ground; this causes incorrect operation and may damage the unit. Connect the speaker directly across the two terminals.
• USB connector: USB type “A” connector for a USB memory key; audio files are copied between the key and the system’s internal SD card memory.

Remote I/O connector

A six terminal pluggable connector (6 pos Euro) gives remote access to start and stop control and to the play relay output, so a user supplied pushbutton, motion sensor or other control device can trigger playback by contact closure.

• Pin 1: common.
• Pin 2: stop; stops playback, if playing.
• Pin 3: start; plays the active message.
• Pin 4: play relay output, normally open.
• Pin 5: play relay output, common.
• Pin 6: play relay output, normally closed.

Controls

• Line in level knob: adjusts the line input level, continuous from −infinity to +0 dBm; set it while recording.
• Mic in level knob: adjusts the microphone input level, continuous from −infinity to +0 dBm; set it while recording.
• Tone adjust knob: sets bass and treble in 1 dB steps, from +10 dB bass and −10 dB treble (fully counter-clockwise) to −10 dB bass and +10 dB treble (fully clockwise); the centre position is 0 dB bass, 0 dB treble.
• Output level knob: sets the playback level of the line output and the speaker output together, from −infinity to +4 dB.
• Record pushbutton: enters record setup mode.
• Start/Stop pushbutton: plays the default message (holding it repeats the message), or stops playback or recording.
• Select pushbutton: selects the message position to record into or play from.
• Speaker pushbutton: turns the on-board monitor speaker on or off, to preview message playback.

Indicators

• Memory OK LED (green): on when the internal memory, or a USB memory key, holds valid audio messages; blinks when the memory is empty or no files are detected.
• Message LED (yellow): blinks the number of the selected message during select, play or record (blink – blink, pause indicates message #2); solid indicates sequential play mode. While choosing a position to record into, it blinks fast if a message is already stored there and slowly if the position is empty.
• Record LED (red): blinks in record setup mode and is solid while recording; also lit while messages are copied from the USB memory key to the SD card.
• Play LED (green): on while the system plays a message.

Recording and playback

Messages can be recorded locally into non-volatile memory with the integrated microphone input or the line input, or recorded in a studio and loaded over the high speed USB port. The non-volatile memory keeps the messages through a power outage.

• Recording: press Record (the Record LED blinks), press Select to choose the message position, press Start/Stop to begin recording (the Record LED turns solid), and press Start/Stop again to stop recording or to exit record mode.
• Erasing: enter record setup mode, select the message number to delete, then press and hold Start/Stop for about 2 seconds.
• Choosing the active message: press and hold Select for 2 seconds; the unit shows the current active message. Further presses step through all valid messages, #1 to #4, and then the “Play Sequential” mode (solid Message LED). Press Start/Stop to store the choice; it is kept through power outages.
• Standard mode: each trigger plays the same message position.
• Sequential mode: each trigger plays the next message until the last one, then starts again from the first.
• During playback the Play LED is lit and the Message LED blinks the number of the message playing.

Audio files and USB transfer

The internal 1 GB SD card holds over 16 hours of MP3 audio or over 1.5 hours of WAV audio. Messages may be any length, from a couple of seconds to several hours.

• Formats: WAV (44.1 kHz, 16 bit) or MP3 (44.1 kHz, 32–320 kbps, VBR). Local recordings are made as WAV, 44.1 kHz, mono.
• Files may be mono or stereo, but the unit plays only the left channel.
• Name files by number: 1.mp3 or 1.wav goes to message position 1, and so on up to 4.mp3 or 4.wav for position 4. Files beyond the fourth are played only in sequential mode.
• If the card holds two files with the same name but different suffixes, the MP3 file plays and the WAV file is ignored.
• USB key folder “Complete”: all files on the Minimac2 are deleted and replaced with the audio files in this folder.
• USB key folder “Delta”: audio files of the same name are replaced with the files in this folder.
• USB key folder “Upload”: when the key holds only an empty Upload folder, all audio files are copied from the Minimac2 into it.
• If the key has both a “Complete” and a “Delta” folder, no files are transferred and the LEDs show an error.