Williams AV FM 557-12 – FM+ System Package with 12 R37 Receivers

Product Overview

The Williams AV FM 557-12 FM+ system package equips mid-size venues with ADA-compliant assistive listening built around dual transmission: the FM+ T55 transmitter broadcasts to the twelve included PPA R37N FM receivers and streams the identical audio over the building's Wi-Fi network at the same time. Sanctuaries, lecture halls, and municipal meeting rooms get a complete listener-side kit — receivers, surround earphones, neckloops, and ADA signage — with a transmitter that integrates into a modern networked AV environment.

Product Description

Williams AV's FM+ platform delivers both FM and Wi-Fi audio from one half-rack transmitter for close to the price of a traditional FM-only system, which is why it has become a standard specification for assistive listening upgrades. In this package the T55 transmitter accepts a balanced or unbalanced mic or line-level source on its combination XLR/1/4-inch input — phantom power is selectable for condenser microphones — and processes it through onboard DSP with selectable compression ratios and high-pass/low-pass filters chosen for speech clarity. Setup runs through a 3.12-inch OLED display, with a hosted web page and Telnet-over-Ethernet control available for remote administration and integration with third-party control systems. The transmitter operates on 17 selectable wideband channels between 72.1 and 75.9 MHz, allowing several systems to coexist within one facility. On the receive side, each PPA R37N body-pack runs about 50 hours on its included AA alkaline batteries, locks to the house channel to prevent accidental retuning, and feeds the included EAR 022 surround earphones; three NKL 001 neckloops serve listeners whose hearing aids or cochlear implants have telecoils. The FM broadcast supports an unlimited audience, so growth means adding receivers, not replacing the head end. An FCC 15.203-compliant antenna and professional installation are required by the FCC and are not part of this base package — integrators wanting antenna, chargers, batteries, and a rack kit included should specify the FM 557-12 PRO bundle. The complete family of transmitters, receivers, and accessories is in our Williams AV collection.

Key Features

• Dual FM and Wi-Fi Transmission — One T55 transmitter serves the included FM receivers and smartphone listeners over the venue network simultaneously.
• Twelve-Receiver Listener Kit — PPA R37N body-packs with EAR 022 surround earphones cover the receiver inventory ADA guidelines expect for mid-size assembly spaces.
• Hearing Aid Compatibility — Three NKL 001 neckloops deliver audio directly to telecoil-equipped hearing aids without earphones.
• 17 Wideband Channels — Selectable frequencies between 72.1 and 75.9 MHz keep multiple systems interference-free in the same building.
• Speech-Focused DSP — Adjustable compression and filtering at the transmitter improve intelligibility for listeners with hearing loss.
• Long Battery Life — Receivers run approximately 50 hours on the included AA alkaline cells, or about 32 hours on optional NiMH rechargeables.
• Web and Telnet Management — The hosted web interface and Ethernet Telnet control support remote monitoring and control-system integration.
• Half-Rack Form Factor — The transmitter occupies one EIA space, half width, and rack mounts with optional RPK 005 or RPK 006 kits.
• ADA Compliance Support — The system meets 2010 ADA hearing assistance guidelines and includes the IDP 008 availability plaque.

Typical Applications

• House of worship
• Auditorium
• Government space
• Training room
• Multi-purpose room
• All-hands room

Technical Specifications

Frequently Asked Questions

How does this package differ from the FM 557-12 PRO?

Same transmitter, same twelve receivers. The PRO version adds the ANT 005 antenna, RPK 005 rack panel kit, a CHG 3512 12-bay charger, and NiMH rechargeable batteries; this standard package lets integrators specify those items separately.

What audio feed should I plan for the transmitter?

A line-level output from the venue DSP or mixer is typical, connected to the combination XLR/1/4-inch input. The input also accepts microphones directly, with selectable phantom power and gain adjustable in 1 dB steps.

Do listeners need an app for Wi-Fi listening?

Smartphone listeners stream the audio over the venue's Wi-Fi network. The venue's network must be in place first — the transmitter joins an existing network rather than creating one.

Can the receivers be locked to one channel?

Yes. The PPA R37N supports channel lock, and its seek button is recessed inside the battery compartment, preventing audience members from changing channels during an event.

What antenna does this transmitter require?

An approved FCC 15.203-compliant antenna — ANT 005, ANT 021, ANT 024, or ANT 025 — installed professionally, per FCC requirements. The Williams AV Antenna Selection Install Guide details the options for each installation type.

What is the warranty?

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