Car High to Low Frequency Converter Auto Stereo Line Speaker Level Adapter TD22

Adding a subwoofer to a factory stereo hits one obstacle immediately: the head unit has no RCA outputs, only speaker wires. This converter drops those speaker-level signals to the line level an amplifier expects, so the original radio and steering controls stay exactly where they are.

Powered, so the amp switches with the stereo

Converters come in passive and active forms and the TD-22 is the active type. It takes a 12 V feed, which the supplier notes can run in parallel with the subwoofer's own power line, and provides a blue REM wire for the amplifier's remote terminal. The amp then powers up and down with the stereo rather than running the whole time the ignition is on.

The delay circuit is the part you notice

Every amplifier install risks a thump through the speakers at switch-on, and with a subwoofer it is loud enough to make you wince. The TD-22 holds the remote signal briefly so the amp comes up after the stereo has settled, which is what kills the pop.

Key features

• Speaker level to line level: feeds an amp or sub from a head unit with no RCA outputs.
• Built-in turn-on delay: stops the start-up thump through the speakers.
• REM output: switches the amplifier with the stereo instead of the ignition.
• 85 x 53 mm footprint: hides behind the head unit or under a seat.

Specifications

• Model: TD-22
• Dimensions: 85 x 53 x 23 mm
• Power supply: 12 V
• White lead: left speaker positive
• Black/white lead: left speaker negative
• Grey lead: right speaker positive
• Grey/black lead: right speaker negative
• Black lead: earth
• Red lead: 12 V power
• Blue lead: REM control to the amplifier
• Casing: transparent plastic
• Input and output levels, impedance and power handling: not published by the supplier

What's in the box

• 1 x TD-22 high-to-low frequency converter

Colour can vary slightly with lighting and screen settings. A small part, but it decides whether the rest of the install sounds right.