Stereo Audio "HUM KILLER"

The RDL EZ-HK1 Stereo Audio HUM KILLER addresses ground-loop hum in unbalanced stereo audio connections through galvanic isolation. It combines stereo RCA phono and mini-jack interfaces in a compact passive unit, allowing isolation and conversion between the two connector formats. A switch-selectable ground lift provides control over output ground isolation for portable or permanently installed systems.

Ideal Use Cases

The EZ-HK1 is intended for unbalanced stereo systems in which a ground loop is introducing audible hum. It supports equipment operating at a nominal -10 dBV level and is suitable when the source and destination use RCA phono jacks, stereo mini-jacks, or different formats on each side of the connection. Its portable-use capability makes it suitable for temporary system configurations, while its 1/6-rack-width mounting size supports permanent installation. The output ground-lift switch is useful when the required grounding arrangement needs to be selected for a particular connection.

Why Choose This Model

This model combines audio ground-loop hum elimination, unbalanced stereo galvanic isolation, connector-format conversion, and selectable output ground isolation in one device. Stereo RCA phono and mini-jack connections are provided for both input and output, reducing the need to choose a model dedicated to only one connector format. Gold-plated RCA connectors provide the specified RCA interface, while the passive circuit operates at nominal unity gain. The result is a focused solution for isolation and routing rather than amplification or signal-level adjustment.

Installation and Integration

Connect the stereo source through the RCA phono input or stereo mini-jack input, then use the corresponding or alternate output format required by the receiving equipment. The EZ-HK1 specifically supports conversion between mini-jack and RCA formats. Its inputs are ground-isolated, and output ground isolation is controlled by the ground-lift switch. Both the input and output are specified for a nominal -10 dBV signal level, with 10 kΩ input and output impedance. The case measures 2.9 inches (7.4 cm) wide by 3 inches (7.6 cm) deep. Its 1/6-rack-width mounting size and support for portable or permanent use provide flexibility when integrating it into an existing audio system.

Performance Highlights

The passive circuit provides nominal unity gain and a specified frequency response of 20 Hz to 20 kHz within ±1 dB. Input impedance is 10 kΩ, and output impedance is also 10 kΩ. Unbalanced stereo galvanic isolation directly addresses the electrical ground path associated with ground-loop hum, while switch-selectable output isolation allows the grounding configuration to be adjusted at the output jacks. These specifications define the EZ-HK1 as a line-level isolation device for nominal -10 dBV stereo audio connections.

What Makes It Different

The EZ-HK1 brings several related functions together: stereo ground-loop hum elimination, galvanic isolation, RCA and mini-jack connectivity, and conversion between those connector formats. Its ground-lift function is switch-selectable rather than fixed, giving the installer control over output ground isolation. The combination of a passive unity-gain circuit and gold-plated RCA connectors keeps the design centered on the stated task of passing and isolating an unbalanced stereo signal. Its compact 2.9-by-3-inch footprint also accommodates both portable applications and permanent installations without changing models.

Final Assessment

The RDL EZ-HK1 is a purpose-built choice for isolating nominal -10 dBV unbalanced stereo audio connections affected by ground-loop hum. It is particularly well matched to systems requiring RCA phono and stereo mini-jack connectivity, including connections that require conversion from one format to the other. With passive unity-gain operation, a 20 Hz to 20 kHz response, ground-isolated inputs, and switch-selectable output ground isolation, it provides a clearly defined solution for stereo audio integration.