【HQC-21HL | Line Output Converter for Adding a Power Amplifier and Subwoofer to the OEM Head Unit】

You want to add a power amplifier and a subwoofer to a factory head unit—or to a head unit that does not have pre-out terminals. That’s where HQC-21HL comes in.

Even if you want to upgrade your system based on the OEM audio without replacing the head unit, you can extract the signal needed to connect from the speaker outputs to an amplifier, etc. It’s also an easy-to-consider converter for situations where you want to add a subwoofer, but you don’t have pre-out and don’t know how to make the connection.

On vehicles with complex OEM audio configurations—such as BMW, Mercedes-Benz, Lexus, and others—the head unit may not be easy to replace. From luxury cars like the Celsior and Crown to vehicles like the Suzuki Swift, HQC-21HL is a viable option when you want to rethink the setup from the power amplifier onward while making use of the factory system.

Signal Conversion Designed with Sound Quality and Noise in Mind

HQC-21HL uses a high-performance ultra-compact isolation transformer. It’s designed to minimize concerns such as changes in sound quality when extracting signals from the factory system, as well as the effects of noise from the vehicle side.

Based on the sound of the OEM audio, it can be widely used for in-car system upgrades—for example, when you want to drive the speakers properly with an external amplifier, or when you want to add thickness to the low end with a subwoofer.

A Product Whose Finish Changes Depending on How It’s Installed

Adding a converter isn’t the end of the job. The OEM audio configuration, the vehicle’s signal conditions, and the combination with the added amplifier and subwoofer will change the connection method and even the approach to adjustment.

At LOGON, after confirming your vehicle model and the OEM system, we’ll sort things out together—such as how much of the factory setup to retain and how to combine the amplifier and subwoofer. We’ll fine-tune not only the wiring processing and installation method, but also the balance when you turn the volume up after installation, and how well it matches the music you usually listen to.

“I want to keep the OEM navigation, but I’d like a little more depth and body to the sound.”
“I want to add a subwoofer to a head unit that has no pre-out.”
“I want to use an external amplifier to make my current speakers sound a bit more solid.”

For consultations like these, we’ll guide you to the best method for your vehicle, including options such as the HQC-21HL. Since compatibility and installation details vary by vehicle model, year, and OEM audio specifications, let’s decide the direction together while checking the actual vehicle.

■ Main Specifications / Specs

【Basic Information】
Product name: HQC-21HL
Type: Line output converter for car audio

【Main Features】
・A system-up converter compatible with head units that do not have pre-out terminals
・Extracts signals from the speaker outputs for connecting an external amplifier and a subwoofer
・Uses a high-performance ultra-compact isolation transformer
・Designed with flat frequency characteristics in mind

Connection methods and installation details will vary depending on the vehicle model and OEM audio specifications.