Large-area, 48-volt induction loop amplifier with network control

The Williams AV Digi-Loop DL210 NET D 2.0 is a large-area, dual-channel induction loop amplifier designed to extend hearing support to T-coil devices. It combines two loop outputs, Dante™ audio input, Ethernet-based control, flexible analog inputs, and integrated calibration tools in a 2 RU rackmount chassis.

Ideal Use Cases

This model is suited to large spaces such as auditoriums and gymnasiums. With both outputs driven, the specified perimeter-loop coverage is 31,400 sq. ft. (2,917 sq. m.) for a 1:1 aspect ratio or 51,660 sq. ft. (4,800 sq. m.) for a 3:1 aspect ratio. The 25 V, 70 V, and 100 V high-level input also supports integration with distributed audio and paging systems.

Each loop output is rated for 12 Arms (17 Apk), allowing the amplifier to serve demanding loop installations. The supported loop resistance range is 0.5 to 3.0 ohms DC, while the rated load is 0.5 ohm DC with 135 µH inductance.

Why Choose This Model

The DL210 NET D 2.0 provides Dante™ connectivity through a dedicated 100 Mbps RJ-45 input. It supports 44.1 and 48 kHz sample rates, 24-bit resolution, and a minimum latency of 2 ms. Two configurable mic/line inputs accept microphone, -10 dBV, +4 dBu, or +8 dBu signals in balanced or unbalanced configurations. A 48 V phantom supply is available for compatible microphones.

Input mixing, parametric equalization, compression, metal-loss compensation, high-pass and low-pass filtering, AGC, audio delay, and output levels are adjustable. Configurations can be saved and loaded, supporting repeatable setup and operation.

Installation and Integration

The amplifier fits a standard 19-inch rack and occupies 2 RU. Overall dimensions are 19 inches wide by 3.5 inches high by 12 inches deep, with a 17-inch-wide chassis. The internal universal power supply accepts 100–240 VAC at 50/60 Hz and is rated at 250 watts. Variable-speed, temperature-controlled fan cooling supports operation in environments from 0–35°C (32–95°F) and 0–90% relative humidity.

Connection options include Ethernet, USB standard-B, RS-232, two mic/line terminal-block inputs, a high-level input, line outputs, loop-output terminal blocks, and a front-panel 1/4-inch stereo headphone jack. The headphone monitor source can be selected from an input or output through the menu. The line outputs mirror the loop-output audio.

Function control and calibration are available through the DigiLoop PC App over Ethernet. The application requires Windows 7 or higher, while firmware updates are performed through USB. Front-panel operation is provided through a backlit blue LCD and a combined control button and dial.

Performance Highlights

Each loop output delivers a continuous drive voltage of 33.3 Vrms (47.1 Vpk). Loop frequency response is specified at 45 Hz to 9.0 kHz, ±2 dB referenced at 1 kHz, with rated loop THD below 1% at rated output current using a 1 kHz sine wave. Audio delay is adjustable from 0 to 165 milliseconds.

Loop Output A can alternatively provide a switchable Class D speaker output rated at 225 watts into 4 ohms or 125 watts into 8 ohms. Its specified frequency response is 20 Hz–20 kHz with 0.07% THD.

What Makes It Different

Integrated commissioning tools include a test-tone generator with pink noise and loop-current adjustment and matching. The amplifier also provides loop testing, priority-input selection with an adjustable threshold, a loop-fault relay, and open-circuit, short-circuit, and thermal protection. The fault relay is integrated into the RS-232 DB-9 connection and is rated at 2.0 A at 30 VDC.

The product is designed to meet IEC 60118-4 when correctly designed, installed, and commissioned, with test specifications provided to IEC 62489-1. Listed approvals include CE, UL, ULC, FCC, Industry Canada, RoHS, WEEE, CB Scheme, and RCM.

Final Assessment

The DL210 NET D 2.0 brings dual-channel loop amplification, Dante™ input, network-based control, flexible signal integration, and built-in calibration capabilities together in one rackmount unit. Its large specified coverage areas, 12 Arms-per-output rating, extensive audio adjustment options, and two-year warranty make it a well-documented solution for large-area T-coil hearing-support installations.