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White rectangular outdoor volume control with rotary knob and weatherproof enclosure

Monoprice Inc.

Monoprice 138178 300 W Outdoor Volume Control

SKU CH-RA2H-SY7YJ

Outdoor volume control with auto impedance matching supports up to 300 watts in a weather-resistant enclosure

  • Product typeVolume Control
  • Product weight1.6
  • Key featuresAllows you to connect multiple speaker pairs to a single pow
  • Connect multiple speaker pairs to one amplifier
  • Auto impedance matching protects your amplifier from damage
  • Handles up to 300 watts of amplifier power
  • Weather resistant enclosure for outdoor installation
  • Model 138178 weighs 1.60 units

300-Watt Outdoor Volume Control

The Monoprice 138178 is a rotary volume control designed for outdoor audio installations. It allows you to connect multiple speaker pairs to a single power amplifier or receiver. The unit features automatic impedance matching to protect the amplifier from damage caused by low impedance loads. Its weather-resistant enclosure ensures durability in exposed environments.

Auto Impedance Matching and Weather Resistance

The built-in impedance matching circuitry automatically adjusts the speaker load presented to the amplifier, preventing overload when multiple pairs are connected. This protection allows the system to operate safely with amplifiers delivering up to 300 watts of output power. The waterproof enclosure shields the internal components from moisture and weather, making it suitable for permanent outdoor mounting.

Amplifier Power and Wiring Compatibility

Verify that your amplifier's maximum output power per channel does not exceed 300 watts to stay within the device's rated capacity. Ensure your speaker wiring is rated for outdoor use and that the impedance of your connected speakers is compatible with the matching range. The unit requires a standard single-gang electrical box for installation, which is not included.

How it compares

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

Price $32.99
Cheaper than about 58% of the 3,838 comparable items (median $41.99).

Specifications

Product
Brand nameMonoprice
Model name138178
Part number138178
Product typeVolume Control

Questions about this item

How often does the impedance-matching circuitry in the Monoprice 138178 need checking or replacement?

The unit has no user-serviceable parts; the auto impedance matching is handled by fixed internal components that do not require periodic maintenance.

What is the first limit reached when driving the 300-watt outdoor volume control continuously at high level?

The 300 W amplifier power rating is the primary limit; exceeding it risks damage to the amplifier rather than the control itself.

Does the weather-resistant enclosure of the 138178 get hot or make noise during all-day outdoor use?

The passive design has no fan or moving parts, so it runs silently and generates only minimal warmth under normal operation.

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