Lectrosonics Digital IEM System

M4 Transmitter

The half-rack transmitter can accept up to four inputs from digital or analog sources. The inputs can be configured as follows:

• Four analog inputs using all four jacks
• Two digital inputs using jack 1 and two balanced analog inputs using jacks 3 and 4
• Four digital channels using jacks 1 and 2

The input connectors are full size balance XLR types for AES/EBU and balanced line level analog signals. Input preamp circuits use a special balanced amplifier with very high common mode rejection to minimize hum and noise

Either analog or AES/EBU digital input signals are converted to an internal 24-bit digital format which is then encoded, organized into packets, and passed to an RF modulator using spread spectrum techniques and error correction for robust reception. The modulated RF signal is filtered before and after amplification to suppress out-of-band noise and spurious signals, and a circulator/isolator guards against intermodulation interference (IM)

The transmitter can be free-standing or rack mounted in single units (via an optional rack mounting kit) or in a dual configuration using supplied hardware

A USB port is provided for firmware updates

Frequency Range

Using the license free 902 to 928 MHz ISM band, this system is outside the normal broadcast frequencies thus providing both technical and operational advantages over standard analog systems

Multi-Channel Capability

Quadra can be configured to provide either 2 or 4 audio channels. In the 2 channel mode, eight different frequencies are available, each with two audio channels. In the 4 channel mode, four different frequencies are available, each with four audio channels. Multiple Quadra systems can be operated in the same location to provide up to 16 total audio channels between all units

The performer can then use the on-board mixer to tailor the audio output to his or her tastes or the requirements of the performance at hand

Ultra Low Latency

Signal delay with digital devices is a concern, particularly when performing artists hear their own voice through the system. Quadra employs new technology to drastically lower the throughput latency to levels far below industry standards. With analog inputs at the transmitter, the Quadra system adds a mere 1 ms of latency. With digital inputs, the latency is 2.3 ms for 48 kHz sources and 1.8 ms for 96 kHz sources

Audio Signal Monitoring

The signals at the transmitter inputs can be monitored in two ways: using the LCD bar-graph meters for levels and with headphones listening to the actual signals. The LCD bar-graph meters show the audio level range from -60 to 0 dB. When the signal exceeds +20 dBu at an input, the bar graph indicates this with a bright "!" at the top of the bar on that channel

Road-Worthy Construction

Unlike consumer and "semi-pro" equipment, the Quadra system was designed and developed with the professional touring, installation, theater and broadcast customers in mind

The receiver case is machined out of solid metal, yet it is lightweight and sleek in order to be comfortable on the artist's body

The transmitter chassis is all-metal and features a built-in power supply with detachable AC cable. The AC connection includes a wire bail to ensure that the cable does not become disconnected accidentally

Superior Sound Quality

Conventional in-ear wireless monitor systems rely on decades-old technology: FM transmission with multiplexed, companded audio. The Quadra system employs recently developed technology to provide ruler-flat frequency response from 20 Hz to 20 kHz and maximum channel separation. In addition, the digital audio lacks a compandor and the associated artifacts. The result is crystal clear sound with extremely low distortion of <0.05%

The headphone amplifier provides 100 mW at 32 Ohms, making it possible to drive even the most demanding earbuds or headphones to sufficient levels for the most discriminating artists

Since all mixing is accomplished in the digital domain, the Quadra system provides superior sound even with complex material used in the 4 channel mode and mixed at the top panel by the artist

Quadra System

The new Quadra system from Lectrosonics features digital RF modulation, two or four channels of 24-bit/48 kHz digital audio, analog or digital inputs, and a unique mixing interface for performing artists. The Quadra system operates in the license-free ISM (industrial, scientific, and medical) band between 902-928 MHz and has a throughput latency of 1 ms for the analog inputs and less than 0.5 ms for the digital inputs

The M4R diversity belt pack receiver features a user-friendly interface with a high-resolution, backlit LCD and membrane switches. A four channel mixer enables the performer to tailor the mix in real time, based on what is sent to the transmitter from the monitor console. Several channel setups and knob configurations are available, providing users with a variety of choices as to how the system operates. The M4R runs for 6 hours on three alkaline AA batteries

The M4T half-rack transmitter features transmission power of 200 mW for extended operating range. Locking XLR connectors facilitate up to four channels of either analog or digital (AES/EBU) audio sources to be applied to the transmitter. A large, high resolution, backlit LCD and large membrane switches provide an intuitive interface that is operable even in the most challenging environments. The included hardware supports rack mounting of two M4T units together in a 1RU configuration