🔍 What to Check
When selecting a volume controller, pay attention to the following specifications that should be listed in the product datasheet:

• Maximum load power (e.g., 10 W)

• Rated operating voltage / line (e.g., 70 V, 100 V, or low-voltage system)

• Type of control (e.g., resistive divider, transformer type, step attenuator)

• Number of adjustment steps (if stepped) or range (if continuous)

• Minimum/maximum load (minimum speaker impedance)

• Frequency range, total harmonic distortion, signal-to-noise ratio — if high audio quality is required

• Installation and environmental conditions (temperature, humidity)

• Dimensions and mounting type (wall-mounted, flush-mounted, etc.)

🛠 Typical Reference Values
Based on similar devices, you can expect approximately the following:

• Power rating of 10 W — suitable for small public address or intercom systems.

• Likely designed for 70 V or 100 V speaker lines, typical for PA systems.

• If it’s a stepped controller — may have 10–11 volume positions (for example, AT-36 has 11 steps).

• If the body is wall-mounted or built-in — dimensions are typically around 80×80 mm, similar to standard wall devices.