Williams AV FM 557 Large-Area Dual FM Plus and Wi-Fi Assistive Listening System with FM T55 Transmitter, (4) PPA R37N Receivers, (4) EAR 022 Earphones, (2) NKL 001 Neckloops and IDP 008 ADA Wall Plaque

Key Features
- Includes: (1) FM T55 Transmitter, (4) PPA R37N Receivers, (4) EAR 022 Surround Earphones, (2) NKL 001 Neckloops and (1) IDP 008 ADA Wall Plaque

Specifications
- FM T55 Transmitter:
- Operating Frequencies: 72.1-75.9MHz , 17 wideband channels (selectable)
- Frequency Accuracy: ±2 ppm stability
- Deviation: ±75kHz maximum
- Pre-Emphasis: 75 microsec
- Frequency Response: 31-16000Hz, ±3 dB
- Signal-to-Noise Ratio: 67dB Transmited RF
- Total Harmonic Distortion: Less than 0.25% @ 1kHz (RF output)
- Common Mode Rejection: 57dB @ 1kHz, Mic or Line
- Rack Mount: Standard 19" Rack, one EIA rack space high, 1/2 space wide
- Ethernet: RJ-45, 10/100 Base-T IEEE 802.3 compliant, unique MAC address
- Weight: 3.2 lbs
- PPA R37N Receiver:
- Channels: 17, accessed via seek button in battery compartment
- FM Deviation: 75kHz
- De-Emphasis: 75µS
- AFC Range: ± 120kHz
- Sensitivity: 2µV at 12dB Sinad with squelch defeated
- Input Overload: 100mV
- Frequency Response: 200–15kHz
- Modulation: FM, +/- 75kHz peak deviation

- Signal-to-Noise Ratio: 65dB min @ 100uV

- Receive Antenna: Integral with earphone/headphone cord
- Audio Output: 35 mW, peak into 16 ohms
- Output Connector: 3.5mm stereo/mono phone jack
- Weight: 4.6oz
- EAR 022 Earphones:
- Plug: 3.5mm mono
- Driver Size: 23mm
- Nominal Impedance: 32Ω
- Freq. Response: 20-20kHz
- Max Power Input: 30mW
- Sensitivity: 118dB @ 1kHz
- Weight: 15g