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How to Hook up Amp Without RCA Jacks

There’s no denying that adding a car amp will provide more power to the speakers, allowing for a much cleaner sound and a better overall performance. A good amplifier will also raise the soundstage and enhance the detail in every song at any volume. This is especially true if you still have the factory stereo.

Every now and then We get e-mails and comments from readers who like to upgrade their car stereo setup. One recent one asked, “How can I hook up an amp without RCA jacks?”.

Some people think that installing an amplifier in their vehicle is hopelessly complicated and best left to a professional, let alone hooking up an amp to a factory radio.

Typical amp installations rely on RCA ports for what is arguably the cleanest-sounding connection from the system’s headunit to the amp itself. However, there are some situations which require different workarounds. For instance when the headunit has no RCA outputs on the back.

Disclaimer

First of all, we’d like to point out that aftermarket stereos (especially high-end ones) are featured with a wide range of audio shaping goodies in addition to a ton of bells and whistles compared to most stock receivers.

That said, if you’re an avid audiophile who’s seeking superior sonic performance, consider upgrading your car stereo. However, if your vehicle is equipped with a fancy infotainment system that for aesthetic or even for the vehicle’s electronic system functionality simply can’t be replaced without great difficulty, but you still want to add an amplifier to your sound system, read on… we listed down below three ways to how to hook up an amp to a factory radio.

3 ways to hook up an amp without RCA jacks

Method #1 – Use a line output converter

A line output converter, or LOC for short, converts a speaker-level output signal, between the radio or factory amp and the speakers, down to a low-level RCA preamp-level signal that your amplifier can understand.

That said, if your stereo doesn’t have preamp outputs, a line output converter is a great solution. All it takes is to connect the receiver’s speaker wires to the LOC’s inputs and use RCA cables to run the signal from the LOC to your amp.

Pros

  • Clean install
  • LOCs come in a wide variety of shapes and sizes
  • High-end LOCs offer great features and power handling
  • LOCs keep the audio signal to your amp pure and ultra-clean

Cons

  • Some line output converters are quite pricey
  • You need to buy an extra component (LOC)

Method #2 – Use amp’s high level (or Speaker-Level) inputs

Another way to connect your amp to a factory radio lacking RCA jacks is to use speaker level inputs, which are also referred to as high-level inputs. The latter is said to have a high voltage level than that of a standard preamp output connection, which is not correct.

The terms low- and high-level are somewhat misleading as they’re not referring to the level of voltage. Despite the fact that the voltage level itself does tend to fall in line in that way, it is not what makes high or low level what they are.

I mean think about, if you set your multimeter for continuity and test the speaker level output of a radio, you’d notice that there’s no continuity from any of the speaker wires to ground. This is high-level output.

In the same way if you perform the same test on the preamp-output of the radio, you’d find that the negative of the output does in fact have continuity to ground. This is what makes it a low-level output.

Having said that, the level of voltage itself only tell whether the output has continuity to ground or not. In other words, it doesn’t have any impact on whether an output is high or low level.

It must be noted, however, that not all car amplifiers are featured with speaker-level inputs. So, if your factory radio isn’t equipped with preamp outputs, make sure the amplifier you’re going to purchase has speaker level inputs.

Pros

  • Cheap option – doesn’t require any extra components

Cons

  • Not all amps have speaker level inputs
  • Low level inputs offer what is arguably the cleanest signal compared to high-level inputs

Method #3 – Use speaker wire to RCA adapter

The third way to hook up an amplifier to a stock radio is to use speaker wire adapters. What these adapters do is that they allow you to convert speaker wires into RCA plug connectors, so you can connect your car stereo’s speaker outputs directly into your amp, or any other aftermarket amplifier equipped with RCA inputs that take high-level input signals.

Pros

  • RCA adapters are quite cheap
  • Allows for clean install
  • High level signal requires less amplification from the amplifier (less work)

Cons

  • Most amps do not accept high-level input signals on their RCA inputs.

Final Thoughts

Now that we’ve explained the different ways to hook up an amp to a factory radio, consequently breathing life into your system, you no longer have to live with anemic sound in your car.

Each of the three ways we distilled above comes with its own pros and cons. Which to opt for depends greatly on you own setup and budget.

Alex Brown

Hey There, my name is Alex Brown, I'm a music lover and a car audio enthusiast. I've installed everything from navigation systems to full car stereo systems, remote starters, alarms and beyond. I've been in this industry for years now. I enjoy creating solutions and simplifying everyday needs. My passion for music came at an early age. I love helping people get great sounding gear, thereby, saving the world from bad sound one customer at a time.

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