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White rectangular wall-mount volume control with rotary knob and color kit

Monoprice Inc.

Monoprice 138166 300W Rotary Impedance Matching Speaker Volume Control with Color Kit

SKU CH-4TD5-A9WSP

Connects multiple speaker pairs to one amplifier while matching impedance to protect the amp, handling up to 300 watts and fitting standard single-gang boxes

  • Product typeVolume Control
  • Product weight1.18
  • Key featuresAllows you to connect multiple speaker pairs to a single pow
  • Connect multiple speaker pairs to one amplifier
  • Protects amplifier with impedance matching up to 300 watts
  • Fits standard single-gang low-voltage junction boxes
  • Rotary volume control for each connected speaker pair
  • Lightweight design at 1.18 weight units

Monoprice 138166 Impedance Matching Volume Control

The Monoprice 138166 is a rotary impedance matching speaker volume control designed for whole-home audio installations. It allows you to connect multiple speaker pairs to a single power amplifier or receiver while protecting the amplifier from impedance mismatch damage. The unit supports amplifiers with up to 300 watts of output power and fits standard single-gang low-voltage junction boxes or mounting brackets.

Ideal for multi-room audio systems needing

This control suits installers and homeowners building a distributed audio system where several speaker pairs share one amplifier and require independent volume adjustment in each zone. It is not intended for users who only need a simple passive volume knob without impedance correction, nor for systems where the amplifier already handles low-impedance loads natively without external matching.

Verify amplifier power rating

Before ordering, confirm your amplifier or receiver outputs no more than 300 watts per channel to stay within the device's rated capacity. Ensure your wall boxes are standard single-gang low-voltage types compatible with the control's mounting dimensions. Check that your speaker wiring scheme matches the impedance matching requirements for the total number of connected pairs.

How it compares

Measured against everything we stock in AV Accessories & Components, at today’s prices. Recalculated every night.

Price $24.99
Cheaper than about 66% of the 3,838 comparable items (median $41.99).

Specifications

Product
Brand nameMonoprice
Model name138166
Part number138166
Product typeVolume Control

Questions about this item

What type of amplifier or receiver is required to use this volume control?

You need a power amplifier or receiver that can drive the speaker pairs you intend to connect, with an output of up to 300 watts, so the impedance matching can protect it from excessive load.

Will this work with my existing in-wall speaker wiring and standard junction boxes?

Yes, it fits into standard single-gang low-voltage junction boxes or mounting brackets, so it can replace or sit alongside your current in-wall wiring without special enclosures.

How can I verify the unit is protecting my amplifier after installation?

With multiple speaker pairs connected, the amplifier should run without entering protection mode or overheating, indicating the impedance presented remains within safe limits for up to 300 watts output.

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