Lectrosonics LMb Beltpack Transmitter - Digital Hybrid Wireless, Wide Band

The Lectrosonics LMb Beltpack Transmitter is the latest successor to the line of economical beltpack transmitters designed for applications including theater, house of worship, TV, ENG, video and film production.

The UHF LMb Transmitter is part of the L Series or "Large Bandwidth" line of wireless microphones. The other two components of the series are the LT Beltpack Transmitter and the LR Receiver. All three units share a wide tuning range of three standard Lectrosonics blocks, or 67.5 to 76.8 MHz, depending on the specific frequency band, and employ Lectrosonics' patented Digital Hybrid Wireless technology for compandor-free audio along with compatibility modes for inter-operability with older analog systems.

The LMb transmitter can be configured to operate as a "one touch" device with a single power on/off switch on the top panel, or with full access to all operational parameters using the side panel membrane switches and LCD interface. The top panel switch can also be configured to provide a mute or talkback function. This versatility makes the transmitter perfect for a wide variety of applications.

Frequencies are selectable in 100 kHz or 25 kHz steps across a maximum tuning range of 76.7 MHz. This yields a total of 3,072 available frequencies across three standard frequency blocks. The tuning range varies in other blocks to meet applicable frequency allocations.

The servo bias input accepts mic or line level signals with a wide range of gain adjustment in 1 dB steps. Accurate LED indications on the top panel and a bar graph indicator on the LCD allow precise gain adjustments to be made for the maximum signal-to-noise-ratio and minimum distortion. The limiter in the preamp can cleanly handle signal peaks over 30 dB above full modulation, allowing the input gain to be set high enough to achieve the maximum signal-to-noise ratio.

Compatibility with earlier analog Lectrosonics receivers, Lectrosonics IFB receivers and some receivers from other manufacturers is provided by DSP emulation modes selected in the LCD menu.

The housing is an aluminum extrusion with machined aluminum top and control panels, with an ultra-hard, black electroless nickel finish called ebENi.

• Digital Hybrid Wireless compandor-free audio
• 50 mW RF power
• Compatibility modes for use with analog receivers
• 25 or 100 kHz tuning steps for up to 3,072 selectable frequencies
• Integrated multifunction switch for mute or talkback modes
• Wide range input gain control in 1 dB steps

• Frequency Selection Steps: Selectable, 100 kHz or 25 kHz
• RF Power output: 50 mW
• Pilot Tone: 25 to 32 kHz; 5 kHz deviation (Digital Hybrid mode)
• Frequency Stability: ± 0.002 %
• Deviation: ± 50 kHz max. (Digital Hybrid mode)
• Spurious Radiation: 60 dB below carrier
• Equivalent Input Noise: -120 dBV (A-weighted)
• Input Level:
  • Mic: Nominal 2 mV to 300 mV, before limiting. Greater than 1V maximum, with limiting.
  • Instrument: 1M Ω high level
• Input Impedance: 2K Ω
• Input Limiter: DSP controlled, dual envelope "soft" limiter with greater than 30 dB range
• Gain Control Range: 44 dB; digital control
• Modulation Indicators:
  • Dual bicolor LEDs indicate modulation of -20, -10, 0 and +10 dB referenced to full modulation
  • LCD bar graph
• ​Audio Performance, Digital Hybrid Wireless Mode Only:
  • Frequency Response: 90 to 20 kHz ± 1 dB
  • Low Frequency Roll-Off: -12 db/octave; 70 Hz
  • THD: 0.2% (typical)
• Signal to Noise Ratio @ Receiver Output:

  SmartNR	No Limiting	With Limiting
  OFF	103.5	108
  NORMAL	107	111.5
  FULL	108.5	113

  ^{Note: The dual envelope "soft" limiter provides exceptionally good handling of transients using variable attack and release time constants. Once activated, the limiter compresses 30+ dB of transmitter input range into 4.5 dB of receiver output range, thus reducing the measured figure for SNR without limiting by 4.5 dB.}
• Controls:
  • Top panel slide switch; programmable as power, mute, talkback or no (off) function
  • Side panel membrane switches with LCD interface for power on/off and all setup and configuration controls
• Audio Input Jack: Switchcraft 5-pin locking (TA5F)
• Antenna: Galvanized steel, flexible wire
• Battery:
  • Types: (2) AA alkaline, lithium, NiMH rechargeable
  • Life: Alkaline, 4.5 hours; Duracell Quantum, 7 hours; Eneloop 2400 mAH NiMH, 8 hours
• Emission Designator: 180KF3E
• Dimensions (H x W x D): 3.2 x 2.4 x .8 in | 81 x 61 x 20 mm
• Weight: 5.0 oz | 141 g, with AA lithium batteries and wire belt clip