AS8/AS8TC 8 Channel Automatic Matrix Mixer OPERATING INSTRUCTIONS and trouble-shooting guide
INTRODUCTION The AKG AS8 Automatic Microphone Mixer is an 8 channel, single rack space audio mixer. Using the unique Adaptive Level Proportional mixing algorithm, the automatic action is inaudible and simple to set up. The AS8 offers remote control of all channel levels and the master level. In addition, a sophisticated compressor/ leveller is included for dynamic range control of the audio program material.
GENERAL TECHNICAL DESCRIPTION The AS8 uses a straightforward analog signal path to provide excellent audio performance. This is coupled with a sophisticated microcontroller to implement both the automatic mixing and the compressor/leveller algorithms. The Adaptive Level Proportional automatic mixing algorithm is used by the AS8. This algorithm uses the signal level pattern at the microphones to derive a pattern of channel gains.
INSTALLATION Installing the AS8 properly is simple, and only requires attention to a few issues. The AS8 should be used in a grounded metal rack. If only one AS8 is being used, it should be placed in the Master mode, using the rear panel switch. Erratic performance will result if the unit is in the Slave mode, but no damage will be done to the unit. Proper operation will be restored when the unit is switched to the Master mode. If multiple AS8s are used together, the first AS8 (i.e.
FRONT PANEL DESCRIPTION CHANNEL SECTION CHANNEL LEVEL - Controls the relative signal level of each channel. Normal operation of the Channel Level control is from about the 10 o’clock position to the 2 o’clock position. CHANNEL ON LED - Gives an indication as to which channels are active. LF - (TC version only) Adjusts the low frequency response of the channel. HF - (TC version only) Adjusts the high frequency response of the channel. MAIN SECTION MAIN LEVEL - Controls the overall output level of the AS8.
REAR PANEL DESCRIPTION MIC/LINE INPUTS 1-8 - Accepts balanced or unbalanced signal. Fully balanced differential input, RF filtered. DIR OUT - Provides a line level signal from each individual channel. The direct output is a post-VCA signal. Any attenuation from the auto mixing process, compressor/leveler system or remote attenuation will be reflected in the direct out signal. This provides versatility for different mixing applications such as distributed overhead speaker systems.
REMOTE LEVEL CONTROL PINOUT Pin Number 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Function Channel 1 Wiper Channel 2 Wiper Channel 3 Wiper Channel 4 Wiper Channel 5 Wiper Channel 6 Wiper Channel 7 Wiper Channel 8 Wiper Channel 1-8 CCW Connection (common to all channels, +5V) Channel 1-8 CW Connection (common to all channels, ground) Main CW Connection (ground) Main Wiper Connection Main CCW Connection (+5V) Not Used Reset to Local Mode (see Operating Instructions) RS-232 SERIAL PORT - Provides access to and cont
OPERATING INSTRUCTIONS Setup of the AS8 consists of choosing rear panel dip switch options, setting front panel levels, and adjusting the compressor/leveller (if used). Using the Remote Level Control capability of the AS8 is addressed in the next section. When the power is turned on to the AS8, it will display its LecNet address on the Channel On LEDs for 1.5 seconds before entering normal operation.
REMOTE LEVEL CONNECTIONS The figure below shows several options which may be used for remote level control of the AS8. Pots, switches, and external control voltages may all be used as the application dictates.
SERVICE AND REPAIR If your system malfunctions, you should attempt to correct or isolate the trouble before concluding that the equipment needs repair. Make sure you have followed the setup procedure and operating instructions. Check out the interconnecting cords and then go through the TROUBLE SHOOTING section in the manual. We strongly recommend that you do not try to repair the equipment yourself and do not have the local repair shop attempt anything other than the simplest repair.
SPECIFICATIONS Mic/Line Input Type: Impedance: Input Gain Settings: Maximum Input Level: Tone Controls: Electronically balanced and RF filtered Greater than 2.
SERIAL CABLE WIRING DIAGRAMS The serial port on the AS8 is a minimal RS-232 implementation. The figure shows the wiring diagram to accommodate interconnection with either a 9 or a 25 pin serial port on a PC or other serial device. AMX PROGRAMMING NOTES If you are using an AMX system to control your LecNet equipment, you’ll want to purchase the Lectrosonics PT3 Protocol Translator. The PT3 connects between the AMX bus and any LecNet equipment.
SERIAL PORT COMMANDS AVAILABLE All LecNet devices use a modification of the typical one-to-one connection between two RS-232 compatible devices. LecNet devices have both an RS-232 transmitter and receiver section. The transmitter section is “tri-stated”, or placed in a high impedance mode, until the particular device is addressed.
AUTO/DIRECT MODE COMMANDS Set Auto/Direct Read Flag - Allows the host to change the value of the Direct/Auto Read Flag. If the flag is 0, the AS8 reads the internal Direct/Auto switches to determine the channel status. If the flag is set to 1, the value stored in EEPROM is used. The new flag value is stored in EEPROM. Host sends command - 15 (0F hex) Host sends data byte: 0 or 1, where 0 = read internal switches, 1 = use stored value.
There are several “status” flags that may be set by the host computer. Those flag commands that store the new value in EEPROM will continue to have the new value even if the power to the AS8 is turned off. One of these flags is particularly important when controlling the AS8 from an AMX or Crestron controller. This is Set Remote Level Read Flag, command 7.
CHANNEL LEVELS AND ATTENUATION COMMANDS Get Channel Level - Causes the AS8 to send to the host channel levels, either singly or all eight. Range is from 0- 255, where 0 corresponds to -65.33dBu, and 255 to +20dBu. Host sends command - 3 Host sends 1 byte: a value 0-7 causes the AS8 to output the level of a single channel, 1-8. A value of 8 or greater outputs the level from all eight channels as eight consecutive data bytes. Host receives 1 or 8 bytes: for the channel level(s).
COMPRESSOR/LEVELLER COMMANDS Set Compressor/Leveller Read Switch Flag - Allows the host to set the value of the Compressor/Leveller Read Switch Flag. If the flag is 0, the AS8 reads the internal compressor/leveller In/Out switch to determine whether the system should be active. If the flag is 1, the AS8 will use the value stored in EEPROM. The new value is stored in EEPROM.
Limited Warranty Valid only in the United States. AKG Acoustics warrants AKG products against defects in material or workmanship for a period of one year from the date of original purchase for use, and agrees to repair or, at our option, replace any defective unit without charge for either parts or labor.
