Williams AV FM 557-12 PRO D – Dante-Enabled Hearing Assistance System, 12 Receivers

Product Overview

The Williams AV FM 557-12 PRO D brings Dante network audio into a mid-size hearing assistance system, packaging the FM+ T55 D transmitter with 12 R37 FM receivers and a full set of professional installation accessories. As the successor to the legacy FM 457 systems, the FM+ platform broadcasts over FM and the venue Wi-Fi network from a single half-rack chassis, giving courtrooms, council chambers, theaters, and training facilities an ADA-compliant assistive listening solution that drops cleanly into a networked AV design.

Product Description

Where most assistive listening transmitters terminate an analog feed, the T55 D in this package takes its program audio straight off the Dante network — a meaningful simplification in installations already running a Dante-enabled DSP, since the assistive listening rack needs only a network drop. An analog combination XLR/1/4-inch input remains available for balanced mic or line-level sources with selectable phantom power, so the transmitter works in hybrid signal chains as well. Internal DSP applies selectable compression and high-pass/low-pass filtering, shaping the broadcast for maximum speech clarity. Operators configure the unit from its OLED front panel or the hosted web page, and integrators can drive it from third-party control systems via Telnet over the rear Ethernet port. The 12 included R37 receivers seek across 17 wideband channels between 72.1 and 75.9 MHz, and the package supplies everything needed to manage them day to day: a CHG 3512 12-bay drop-in charger, 12 sets of AA NiMH rechargeable batteries, surround earphones for each receiver, and three NKL 001 neckloops for telecoil hearing aid users. The ANT 005 remote coaxial antenna extends range up to 1,000 feet, the RPK 005 kit mounts the transmitter in a 19-inch rack, and the IDP 008 plaque posts ADA hearing assistance signage at the door. The FCC requires professional installation with an approved antenna, and Wi-Fi streaming uses the venue's existing wireless network. For projects that do not need Dante, the analog FM 557-12 PRO package offers the same receiver count, and the broader Williams AV collection covers spare receivers and accessories.

Key Features

• Dante Audio Networking — The T55 D subscribes to a Dante flow from the house DSP or mixer, removing analog cabling between the audio system and the assistive listening transmitter.
• FM Plus Wi-Fi Delivery — One transmitter feeds the 12 hardware receivers over FM while streaming identical audio to smartphones on the venue network.
• Mid-Size Receiver Package — Twelve R37 body-pack receivers with earphones match the ADA receiver requirements of mid-capacity assembly spaces.
• 12-Bay Drop-In Charging — The included CHG 3512 charger and NiMH battery sets keep the entire receiver inventory charged from a single station.
• Telnet Control Integration — Ethernet-based Telnet commands let Crestron, Extron, or other control processors manage the transmitter remotely.
• Speech-Optimized DSP — Adjustable compression ratios and filter frequencies tailor the audio for listeners with hearing loss.
• 1,000-Foot Coverage — The ANT 005 remote coaxial antenna provides large-area transmission range for full-venue coverage.
• Rack-Ready Hardware — The RPK 005 kit mounts the half-rack transmitter in one EIA rack space; a second unit can share the space with the optional RPK 006.
• Lifetime Receiver Warranty — R37 receivers carry a Lifetime PLUS limited warranty, protecting the largest recurring investment in the system.

Typical Applications

• Government space
• House of worship
• Auditorium
• Training room
• Multi-purpose room
• Commercial meeting space

Technical Specifications

Frequently Asked Questions

Why choose the Dante version over the standard FM 557-12 PRO?

If the venue's audio backbone runs on Dante, the T55 D transmitter receives program audio over the network with no DAC, analog tie line, or extra DSP output card — cleaner signal flow and simpler rack wiring. Analog-only facilities can use the standard PRO version instead.

How is the system commissioned on a network?

The transmitter has a rear RJ-45 port for the control network and joins the venue Wi-Fi for audio streaming. Configuration happens through the front-panel OLED menu or the hosted web page, and Williams AV's WaveCAST networking guide documents recommended network settings.

Are the receivers rechargeable out of the box?

Yes. Twelve AA NiMH battery sets and a CHG 3512 12-bay drop-in charger are included, giving each R37 receiver roughly 32 hours of runtime per charge. The receivers also accept standard AA alkaline cells for about 50 hours.

What does ADA compliance involve for this system?

The package aligns with 2010 ADA guidelines for hearing assistance: it provides body-pack receivers, includes neckloops for telecoil hearing aid coupling, and ships with the IDP 008 wall plaque to publicize availability of assistive listening.

Does the FCC restrict how this is installed?

Yes. The transmitter must be professionally installed with an approved FCC 15.203-compliant antenna; the included ANT 005 qualifies. Williams AV's Antenna Selection Install Guide lists all compliant options.

Can I add more receivers later?

Yes. The FM broadcast supports unlimited listeners, so additional R37 receivers can be purchased individually as audience needs grow, with no transmitter changes required.