Want to keep your factory radio and still add an amp? A line output converter, or LOC, makes it work. It takes the speaker signal your radio already puts out and turns it into RCA signal your amp can use. Here is how we install one in the bay.
- How it works
- Active vs passive
- What you need
- 1. Find the wires
- 2. Tap in
- 3. Mount it
- 4. RCAs
- 5. Remote
- 6. Set the level
- Mistakes
How a Line Output Converter Works
Your factory radio has no RCA outputs. It only has speaker wires, and the signal on them is too strong for an amp's RCA inputs. The LOC sits in between. Speaker wires go in, RCA signal comes out.
Your factory speakers keep playing like normal. The LOC just copies the signal and steps it down.
Active vs Passive LOCs
A passive LOC is small, simple and does not need power. It is a great fit for adding a sub amp to a basic factory radio.
An active LOC runs on 12 volts. Many can sense the audio and turn your amp on, restore bass the factory system rolls off and combine split signals from factory amps. Premium factory systems almost always need one.
What You Need
- Line output converterActive or passive, 2 or 4 channel.
- RCA cablesLong enough to reach the amp.
- Posi-taps or solderFor clean speaker wire taps.
- MultimeterTo find and confirm the wires.
- Add-a-circuitIf you need a remote source.
- Wiring diagramFor your exact vehicle.
AudioControl LC2i PROShop now →
AudioControl LC7i PROShop now →
Wāvtech link4+Shop now →
Elite Audio EA-LOC75Shop now →
Elite Audio EA-LOC55Shop now →
Step 1 Find the Right Speaker Wires
Pull the radio or the factory amp and find the speaker output wires. Each speaker has a positive and a negative. Use a wiring diagram for your car, then confirm with a meter.
For door speakers or a full system, tap a full range signal, usually the front door woofers. Tweeter wires only carry highs, so you will get no bass.
Step 2 Tap the Speaker Wires
Connect the LOC inputs to the speaker wires you found. Positive to positive, negative to negative, left to left and right to right. Soldered and heat shrunk joints are best. Posi-taps are a clean second choice. Avoid cheap scotch-lock taps, since they cut strands and loosen over time.
Step 3 Mount the LOC
Mount the LOC behind the radio, behind a kick panel or near the amp. Keep it away from heat and moving parts, and screw it down so it doesn't rattle. Leave the level knobs where you can reach them, because you will need them in step 6.
Step 4 Run the RCAs
Plug RCA cables into the LOC outputs and run them to the amp. Route them down the opposite side of the car from the power wire to keep alternator whine out. Mark left and right at both ends before you pull them under the carpet.
Step 5 Hook Up the Remote
Factory radios don't have a blue remote wire, so your amp needs another way to turn on. Many LOCs sense the audio and send a remote signal for you. If yours does not, use an add-a-circuit fuse tap on a fuse that only has power with the key on.
Never use constant 12 volts. The amp will stay on all night and drain your battery.
Step 6 Set the LOC Level
The LOC level sets how much signal goes to the amp. Set it first, then set the amp gain. Too much LOC level clips the signal before it ever reaches the amp, and turning the gain down won't fix it.
Once the LOC is set, follow our guide on how to set amplifier gain correctly.
Common Mistakes We See
- Tapping tweeter wires for a full range signal
- Mixing up left and right channels
- Using constant 12 volts for the remote
- LOC level cranked to max
- Scotch-lock taps on thin factory wire
- RCAs next to the power wire
Gear Up to Keep Your Factory Radio
Everything in this guide is in stock and ready to ship.
Want to know what your factory radio is really putting out? Read factory audio signals explained. Ready for the amp? Here is how to install a car amplifier and how to wire a 4-channel amp.
