Overview

The Garmin JL Audio Source Unit Adaptor Plate is a retrofit mounting plate that lets you install a compatible MediaMaster source unit into an existing dash opening that is larger than the current cutout. It covers openings up to 8.17 x 3 in (208 x 80 mm), and the plate itself measures 8.67 x 4.22 in (220 x 107 mm).

The plate is machined from a single piece of aluminum with a black anodized finish that resists UV and corrosion. It uses countersunk mounting holes that sit behind the source unit trim ring, so the fasteners stay out of sight once the head unit or remote is in place.

This is a practical fix for helm and cockpit refits where you are updating an older stereo or remote, but you want clean coverage around the opening without cutting a new panel.

Key features

• Covers oversized source-unit cutouts up to 8.17 x 3 in (208 x 80 mm) for common marine refits
• Overall plate size: 8.67 x 4.22 in (220 x 107 mm)
• Single-piece aluminum plate with a black anodized finish that resists UV and corrosion
• Full-surface gasket and stainless-steel mounting hardware for a tight seal at the dash
• Countersunk mounting holes that stay hidden behind the MediaMaster trim ring

Variants

It is offered in multiple configurations based on the MediaMaster model you are mounting.

The mounting pattern and face fit differ by configuration, while the job stays the same: cover a larger existing opening and give the source unit a clean, flat surface to clamp to at the helm.

• 010-13855-00: Model compatibility MM105. This version is used when installing a MediaMaster MM105 into a larger, previously cut dash opening.
• 010-13860-00: Model compatibility MM55/MMR-40. This version is used when installing a MediaMaster MM55 or MMR-40 into a larger, previously cut opening.

What’s included

• Mounting adaptor plate
• Stainless-steel mounting hardware
• Full-surface gasket

Compatibility and fit

This part is strictly a mounting solution. It does not change wiring, power requirements, or audio connections, so the unit you are installing still needs to be matched to your boat’s existing harness and system layout.

Before ordering, confirm the MediaMaster model you are installing and measure the existing opening. If the old cutout is larger than 8.17 x 3 in (208 x 80 mm), the adaptor plate may not fully cover the edges.

Installation and setup

A dry-fit at the panel is worth doing before final assembly, especially on fiberglass and cored dash surfaces. The full-surface gasket helps keep water from working behind the plate during washdowns, and the stainless hardware helps keep the install stable in vibration.

If the old cutout exposes raw core material, seal the edge before mounting so moisture cannot wick into the panel over time.

Use cases on board

This adaptor plate is a good match for boat owners doing a stereo refresh where an older head unit or remote left a larger rectangular opening at the helm. It keeps the retrofit looking finished, which matters on open boats and consoles where the dash sees sun, salt, and regular spray.