Relay Volume Control Source Selector Module 100K

This module is an audio volume controller and source selector using a relay and resistor network architecture, completely eliminating the drawbacks of mechanical potentiometers (contact resistance, scratching noise, left/right imbalance) while significantly improving sound quality. Volume is adjusted through 1024 step levels via a rotary encoder or remote control, with full MCU management ensuring stable variation without jumps or interference. The resistance value is 100 kΩ. The audio circuit is a purely resistive path using high-precision audio resistors, Japanese NEC signal relays with silver contacts ensuring excellent conductivity, and ENIG (electroless nickel immersion gold) finished PCBs for the audio paths; the control board uses a HASL finish since the audio signal does not pass through it. The module offers 7 different volume step amplitudes (1024-step mode corresponds to 4 LED flashes), allowing adjustment precision to be adapted according to the gain of the power amplifier. It integrates numerous advanced functions: source selection, instant mute, return volume to zero, progressive volume, programmable default startup volume, and excessive volume protection preventing the volume from exceeding a defined maximum level to protect speakers. The power supply is dedicated exclusively to the control system and does not intervene in the audio path; depending on the configuration, the type of power supply may vary to ensure optimal stability without affecting sound quality. Setup procedures (default volume, maximum limit, variation step) are performed via a configuration button and clearly defined validation/back buttons. 

Control is achieved via an ALPS 27 potentiometer. The volume controller is supplied with a source selection module on which 4 pairs of RCA connectors can be installed (sold separately). The power supply ground as well as the left and right channel grounds are independent. All functions can be remotely controlled using the supplied remote control.

User instructions:

1. Method for setting the maximum volume limit: press and hold the adjustment button (bottom left) until the adjustment indicator flashes continuously, then release it. Then adjust the volume to the desired value (for example, set to level 58). Once completed, regardless of operation, the volume will no longer exceed level 58 unless the setting is changed again. Then press the top-right button to confirm; when the indicator stops flashing, the setting has been successfully saved.

2. Method for setting the default startup volume: press and hold the adjustment button (bottom left) until the indicator flashes continuously, then release it. Adjust the volume to the desired value, then press the central OK button at the top right to confirm; when the indicator stops flashing, the setting has been successfully saved.

3. After entering setup mode, if you do not wish to make any adjustments, directly press the return button to exit setup mode.

4. Method for setting the 7 resistance step amplitudes: press and hold the “setup” button at the bottom left for a few seconds until the indicator flashes continuously, release it, press the “left” button to observe the number of flashes, then directly press the “return” button.