Automatic Level Control-Mono-Terminals

The RDL FP-ALC1 is a mono automatic level control designed to deliver consistent output from audio sources whose levels vary. Its split-band automatic gain control is specified for audio transparency, while self-adjusting attack and release times reduce the need for ongoing intervention. A simple single-control setup, gated control and an INPUT OVERLOAD indicator support straightforward configuration. The unit provides a level-control range greater than 20 dB in the convenient RDL FLAT-PAK format.

Ideal Use Cases

The FP-ALC1 is intended for sound systems receiving inconsistent levels from variable audio sources. The supplied application examples include multiple CD changers, satellite receivers and paging sources. In these environments, differences between programs, tracks or source devices can otherwise require repeated manual level changes.

• Multiple CD changer systems with varying source levels
• Satellite receiver audio requiring more consistent output
• Paging sources with variable incoming levels
• Mono sound-system paths that benefit from automatic level control

Gated control is included to avoid level seeking, allowing the automatic control behavior to remain focused on useful incoming audio rather than continually searching for a level.

Why Choose This Model

The FP-ALC1 combines split-band AGC with self-adjusting attack and release times. This design is specified to provide automatic control while supporting audio transparency. Its greater than 20 dB level-control range gives the circuit room to address meaningful variations between sources. Operation is centered on a single setup control, so the unit does not require a collection of interacting adjustments. The INPUT OVERLOAD indicator supplies direct setup feedback; when the indicator flashes, no further adjustment is needed.

Installation and Integration

The input is a 10 kΩ balanced bridging connection and may also be connected unbalanced. Nominal input level is +4 dBu. The output is 150 Ω balanced, may be connected unbalanced and is specified for a +4 dBu output level. These balanced and unbalanced connection options provide flexibility when integrating the mono controller with different source and destination configurations.

Power requires a ground-referenced 24 Vdc supply at 80 mA. The recommended supplies are the PS-24AS for the USA and the PS-24AX for international use; the power supply is not included. Overall dimensions are 1.42 inches high by 3.25 inches wide by 5.75 inches long, or 3.61 by 8.26 by 14.61 centimeters. The specified ambient operating range is 0°C to 55°C.

Performance Highlights

Excluding AGC, frequency response extends from 20 Hz to 20 kHz within ±0.75 dB. THD+N, also specified excluding AGC, is less than 0.15% from 20 Hz to 20 kHz. Noise is below -90 dB relative to a +4 dBu output, while headroom is greater than 18 dB. The listed automatic level range is 16 to +14 dBu, and the gate threshold is 18 dBu from 20 Hz to 3 kHz.

Together, these specifications define both the underlying audio path and the operating boundaries of the automatic level-control function without relying on unspecified processing modes or additional controls.

What Makes It Different

The FP-ALC1 concentrates its functions on one practical task: producing consistent levels from variable mono sources. Split-band AGC, automatically adapting attack and release times, gated control and single-control setup work together without adding a complex operating interface. The INPUT OVERLOAD indicator provides a clear reference during adjustment, and the RDL FLAT-PAK format packages the controller in a chassis measuring only 1.42 inches in height.

Balanced connections are provided for both input and output, yet each may also be wired unbalanced. This makes the unit adaptable to signal paths that do not use the same connection format at both ends.

Final Assessment

The RDL FP-ALC1 is a focused choice for mono systems that need consistent levels from changing audio sources. Its combination of split-band AGC, a greater than 20 dB control range, self-adjusting timing and gated control directly addresses the level variations associated with CD changers, satellite receivers and paging sources. With +4 dBu nominal interfacing, balanced or unbalanced connection options and a single-control setup process, it offers clearly defined integration and operating requirements.