Lectrosonics DM812 Digital Matrix Audio Processor

The Lectrosonics DM812 is a powerful digital audio processing, mixing and routing system. The primary applications are sound reinforcement and conferencing in boardrooms, courtrooms, worship centers, distance learning systems, hotels and other applications with multiple microphones and loudspeakers. The design represents a milestone in DSP technology in its basic architecture and in its processing speed and efficiency.The basic architecture consists of 8 mic/line inputs and 12 outputs with a full DSP-based cross point matrix that allows every input to be routed to any or all outputs. Following the A-D conversion at each input, the signal passes through multiple DSP filters, ADFE (automatic digital feedback eliminator), a compressor and a digital delay. In the matrix, gain is adjustable from -69 to +20 dB in 1 dB steps at each cross point. Each of the 12 outputs provides a digital delay, multiple DSP filters and a compressor/limiter. Versatile, Easy Control The LecNet2 communications protocol supports simultaneous use of USB and RS232 ports by the PC software control panel and a third party serial control system such as AMX or Crestron. Installers can use the GUI to monitor the state of the DM device for the purpose of verifying that commands sent from the 3rd party controller (over RS232) are working correctly. Minimal Latency Studies have shown that even very slight delays in speech can affect the tempo of a conversation or a conference. The effect is sometimes subtle but delays over 10mS can cause real problems - something Lectrosonics have all experienced when talking on a cell phone. The throughput latency of the Lectrosonics DM812 is a scant 2 ms, independent of how much processing is being used. Optimized Architecture Some digital matrix processors give you a "gas gauge" or "resource meter" to show you how much processing power remains available. As you add more input modules, delays, filters, etc. you eventually run out of available DSP resources. There is no gas gauge in the Lectrosonics DM812, simply because they don't need one. No matter how many filters, delays or other processing you engage or how many signals are routed through your this unit, you will never run out of DSP resources. Scalability Some DSP units limit you to a bus of only 8 channels and some give you up to 16. Either way, most systems limit the amount of scaling available within the matrix. With the Digital Audio Network Interface (DANI) bus, the Lectrosonics DM processors have unlimited input scalability. This way, you can design the right system for the job, no matter how complex and sophisticated, without the concern about being limited by the equipment. Patented Automatic Mixing The LecNet 2 automatic mixing algorithm eliminates abrupt switching (gating) and adapts to changes in background noise in the acoustic environment. AutoSkewing lends a subtle but effective priority to the most active channels by further reducing the levels of inactive channels to reduce background noise and also prevents comb filtering by never allowing two competing channels to operate at the same level. The auto mixing takes place at the cross point in the DSP matrix, which allows each input channel to behave differently at each output. The participation of each input channel can be set to one of four modes: Auto, Direct, Override, Background plus a special Phantom mode. Since the mixing activity is applied at the outputs, each input can participate differently at every output. For example, the microphone on input channel 3 can participate in an auto mixing mode at outputs 4, 5 and 6 for sound reinforcement and also provide a continuous, fixed level at outputs 14 and 16 to feed a recorder. Signal Chain The basic architecture consists of mic/line inputs and outputs with a DSP-based full cross point matrix that allows every input to be routed to any or all outputs. Following the A-D conversion at each input, the signal passes through multiple DSP filters, ADFE (automatic digital feedback eliminator), a compressor and a digital delay. In the matrix, gain is adjustable from -69 to +20 dB in 1 dB steps at each cross point. Each of output provides a digital delay, multiple DSP filters and a compressor/limiter. The matrix mixer enables complex signal routing and level controls without limitations. The matrix mixing allows "mix-minus" routing to reduce acoustic feedback and eliminate echoes caused by speaker/mic coupling in teleconferencing applications. The 16x24 architecture actually functions like 24 separate automatic mixers, each with its own NOM mixing bus. Up to 128 macros can be created with up to 64 commands per macro. These macros can be created off-line and uploaded through either the front panel USB or the rear panel USB and RS-232 serial interfaces. Control signals are distributed through multiple units via standard shielded CAT5 cables with RJ45 connectors. Audio is distributed through the EXPANSION ports on the rear panel. Eight different types of filters are available: Low and High Pass (Bessel and Butterworth types), Band Pass, High and Low Shelving and Parametric EQ, plus an OFF position. Six filters are provided at each input and nine filters at each output. In addition, each input also includes 6 notch filters that can operate as fixed or ADFE (automatic digital feedback elimination) types. There is no "gas gauge" or "resource meter" necessary when configuring a system setup. Optimized Architecture is a unique design that allows automatic mixing, matrix mixing, plus all filters to be used on all 16 inputs and all 24 outputs at the same time with an overall latency of less than 2 ms. The latency in a single unit does not change regardless of the number of functions, processes or features selected. Even with 8 units stacked for 128 inputs, the overall latency is still less than 3 ms. Front Panel Its chassis is made of machined aluminum, with a rugged electrostatic powder coated finish and laser engraved nomenclature for high visibility. The front panel provides a graphical LCD interface that allows access and control of settings and adjustments. A USB port is also provided on the front panel for more complete, computerized setup adjustments and control without having to access the rear panel. Rear Panel The rear panel of this Matrix Mixers provide all connections for microphones, line inputs, line outputs, external computer control and EXPANSION ports for "daisy chaining" multiple units or connecting other LecNet2 devices. Logic I/O ports are also provided for remote control and signaling with external pots, switches and LEDs. LecNet2 Software LecNet2 Software is included with this Processor. The software is used primarily for setup, with the configuration saved on file and into the unit's memory for actual operation. Once configured, the DM runs without a host computer. The LCD display and a rotary encoder control knob enable access for fine adjustments without the use of a computer. Switches next to the LCD display simplify the user interface. While the overall configuration is normally created with the software and downloaded into the DM, it is often very convenient to allow fine adjustments to be made after the hardware is installed. Industry standard depluggable connectors are used for audio inputs and outputs, DB25 connectors provide taps for logic control. USB and serial jacks are provided for the computer interface. A quad RJ45 connector block provides expansion ports for "daisy chaining" multiple units or interfacing with another LecNet2 device. The software is user-friendly, with a variety of screens provided for each section of the signal flow and system design. The software runs under Windows XP, Vista and 7 operating systems using a familiar tabbed layout. Two sample screens are shown below as an example of the appearance.