Williams AV FM 557 – FM+ Dual FM and Wi-Fi System, 4 Receivers

Product Overview

The Williams AV FM 557 is the base FM+ system package, pairing the dual FM and Wi-Fi T55 transmitter with four PPA R37N receivers to bring ADA-compliant assistive listening to conference rooms, courtrooms, chapels, and training spaces. Listeners pick up the broadcast on the supplied body-pack FM receivers or stream the same audio to their smartphones over the venue's Wi-Fi network. With earphones, neckloops, batteries, and ADA signage included, the package covers the listener-facing side of a hearing assistance deployment while leaving antenna and rack hardware to the integrator's specification.

Product Description

The FM+ platform exists because venues no longer want to choose between proven FM body-pack receivers and modern smartphone streaming — the T55 transmitter does both at once, from one half-rack chassis, at close to the price of a traditional FM-only system. It replaced the long-serving T45 transmitter and added the operational features commercial installations expect: a 3.12-inch OLED display for menu-driven setup, a hosted web page for network configuration, Telnet command control over Ethernet for room control integration, and DSP audio processing with selectable compression ratios and high-pass/low-pass filters tuned for speech intelligibility. Audio sources connect through a combination XLR/1/4-inch input handling balanced or unbalanced mic or line-level signals with selectable phantom power. The transmitter operates on 17 selectable wideband channels between 72.1 and 75.9 MHz, so several systems can run in adjacent rooms without interference. The four PPA R37N receivers seek across all 17 channels, support channel lock, run approximately 50 hours on the included AA alkaline batteries, and connect the included EAR 022 surround earphones or NKL 001 neckloops through a 3.5 mm jack — the neckloops serving hearing aid and cochlear implant users with telecoils. The FM broadcast supports unlimited listeners, so receiver counts grow with the venue. The FCC requires professional installation with an approved FCC 15.203-compliant antenna, sold separately. For a package with antenna, chargers, rechargeable batteries, and rack kit included, see the FM 557 PRO bundle; the full lineup is in our Williams AV collection.

Key Features

• FM and Wi-Fi in One Transmitter — The T55 broadcasts to FM body-pack receivers and streams over the venue Wi-Fi network simultaneously, covering both listener preferences.
• Four R37N Receivers Included — Body-pack receivers with EAR 022 surround earphones supply the ADA-required hardware for smaller assembly spaces.
• Telecoil Support — Two NKL 001 neckloops deliver audio directly to telecoil-equipped hearing aids without earphones.
• 17 Selectable Wideband Channels — Operation across 72.1–75.9 MHz keeps multiple systems interference-free within one facility.
• DSP Speech Processing — Selectable compression and filtering at the transmitter improve clarity for hearing-impaired listeners.
• 50-Hour Receiver Runtime — Each receiver operates roughly 50 hours on two AA alkaline batteries, which ship in the box.
• Web Page and Telnet Control — Network-based configuration and third-party control integration come standard via the rear Ethernet port.
• Half-Rack Form Factor — The transmitter occupies one EIA space at half width and mounts with optional RPK 005 or RPK 006 rack kits.
• ADA Signage Included — The IDP 008 wall plaque lets venues post assistive listening availability, supporting 2010 ADA guideline compliance.

Typical Applications

• Conference room
• Boardroom
• Government space
• House of worship
• Training room
• Multi-purpose room

Technical Specifications

Frequently Asked Questions

What is the difference between the FM 557 and the FM 557 PRO?

Both include the T55 transmitter and four R37N receivers. The PRO adds the ANT 005 remote antenna, RPK 005 rack panel kit, two BAT KT6 chargers, and rechargeable batteries; this base package ships with alkaline batteries and lets the integrator specify antenna and rack hardware separately.

What else do I need to install this system?

An approved FCC 15.203-compliant antenna (ANT 005, ANT 021, ANT 024, or ANT 025) and professional installation, both required by the FCC. If rack mounting, add an RPK 005 or RPK 006 panel kit.

Does Wi-Fi streaming need any special setup?

The transmitter joins the venue's existing Wi-Fi network — it does not create its own — so the network must be operational first. Williams AV's WaveCAST networking guide documents recommended settings.

Can listeners with hearing aids use the system?

Yes. The two included NKL 001 neckloops plug into any R37N receiver and couple audio magnetically to telecoil-equipped hearing aids and cochlear implants.

How far does the FM signal reach?

With an ANT 005 coaxial antenna, transmission range extends up to 1,000 feet — ample for the smaller venues this package targets, with headroom for overflow spaces.

What warranty backs this system?

The transmitter is covered for two years parts and labor; the R37N receivers carry a Lifetime PLUS limited warranty, excluding earphones, headphones, and batteries.