Lectrosonics IFBR1B Belt-Pack IFB Receiver

The Lectrosonics IFBR1B is a belt-pack IFB receiver that stores 10 frequency presets and runs more than 8 hours on its LB-50 lithium-ion battery.

IFB, or interruptible foldback, sends cues to talent and crew on broadcast and film sets. Directors also use it to monitor program audio. One knob sets the level and power, and an LCD with membrane switches handles frequency and presets, which keeps the receiver easy for untrained users.

Audio and RF

The receiver uses ±20 kHz FM deviation with compandor noise reduction. A supersonic pilot tone keeps the output silent when no transmitter signal is present. The headphone cable doubles as the antenna.

It drives earbuds, headphones, and induction neck loops from 16 to 600 ohms. A mono earpiece works at full output with no loss of battery life.

Power and Build

The LB-50 battery slides in behind an attached door, and a USB port inside takes firmware updates. A multi-color LED turns from green to red as the battery runs down. The housing is machined aluminum, and it comes with a wire belt clip installed. A charger is not included: the optional CHSIFBR1B dock charges the receiver with the battery in place.

Frequency Versions

Trew Audio carries four versions. The VHF version has a red knob and tunes 174.100 to 215.750 MHz. A1 (470.100 to 537.575 MHz) and B1 (537.600 to 614.375 MHz) have blue knobs. The 941 version (941.525 to 959.825 MHz) has a black knob. UHF versions tune in 25 or 100 kHz steps, and the VHF version in 175 kHz steps.

Features

Stores 10 frequency presets
LCD and membrane switches for setup
Headphone cable doubles as the antenna
Drives 16 to 600 ohm earbuds, headphones, and neck loops
8 hours per charge on the LB-50 battery
USB port for firmware updates
Attached battery door
Machined aluminum housing with wire belt clip

What's Included

40106-1 LB-50 lithium-ion battery
27528 wire belt clip
VSR1 Velcro strain relief
Manual

Specifications

Receiver
Operating Frequencies	VHF: 174.100 to 215.750 MHz Band A1: 470.100 to 537.575 MHz Band B1: 537.600 to 614.375 MHz Block 941: 941.525 to 951.975, 952.875 to 956.225, and 956.475 to 959.825 MHz
Frequency Selection Steps	25 or 100 kHz, selectable; VHF: 175 kHz
Sensitivity	1 µV (20 dB SINAD)
Signal-to-Noise Ratio	95 dB, A-weighted
Squelch Quieting	90 dB
AM Rejection	50 dB, 10 µV to 100 mV
Modulation Acceptance	±20 kHz
Spurious Rejection	Over 70 dB
Third Order Intercept	0 dBm
Antenna	Headphone cable
Programmable Memory	10 presets
Audio
Frequency Response	100 Hz to 10 kHz, ±1 dB
Audio Output	1 V RMS into 50 ohms minimum
Minimum Headphone Impedance	16 ohms
Controls, Power, and Physical
Top Panel	One knob for audio level and power
Side Panel	Membrane switches with LCD for frequency and presets
Indicators	Multi-color LED for power and battery status
Battery	LB-50 lithium-ion, 3.6 V, 1000 mAh
Battery Life	8 hours per charge
Current Consumption	120 mA
Operating Temperature	−20 to 45 °C
Weight	3.4 oz with battery and wire belt clip
Dimensions	71.1 × 70.0 × 20.3 mm 2.8 × 2.4 × 0.8 in
Latest Specifications	Specifications are subject to change without prior notice. For current information, visit lectrosonics.com.