How to Wire High Level Input on Amp? – A Detailed Guide

how to wire high level input on amp

It’s unusual for factory radios to have low level or pre amp outputs. In this case, connecting a traditional amp with high level input radios would be difficult at first sight.

Traditional amplifiers and its RCA connections cannot support the high level signals coming from the speaker wires of the head unit. However, a special tool may be used to convert the speaker level signals to an amp-friendly low level input.

Here are the steps on how to wire high level input on amp with the help of a line output converter.

What is a High Level Input?


1. High-level input

To clear things first, high level input is the method of using the speaker wire leads at the back of the head unit to connect to the amplifier, instead of using low level inputs, or the RCA jacks.

Also known as speaker level input, this works by feeding the amplifier the same input signal that comes from the speaker output. The source for the signal ground would be from the radio’s internal electronics.

Modern amplifiers can also be considered as a high level input car amplifier, since they use speaker level inputs already as seen with the latest car audio systems.

This entails easier installation options and arguably cleaner sound outputs since high level input connectors or high level input plugs are accommodated.

2. Low-level input

Unlike amplifier high level input, low level input, or RCA, is typically seen in traditional amps. These systems cannot handle the speaker wire’s amplified, high voltage signals.

In low level input set ups, RCA interconnect cables are utilized to safely wire the amplifier with the head unit. These cables are grounded to the car’s chassis – making it vulnerable to unnecessary noise and possible system interruptions.

Ways to Wire High Level Input on Amp Using a Line Output Converter



  • Line Output Converter (LOC)
  • Wire stripper
  • Electrical butt connectors
  • Electrical tape
  • Wiring diagram

Line output converter, or LOC, is a device used to convert high level signals into a low level, or preamp level, output. With this, you may now use RCA cables to run signals directly from the radio to the amp.

Here’s how you can hook up high level input on amp directly:

Step 1: Familiarize yourself with the line output converter.

There are 7 wires in an LOC (colors may vary)


On the input side: Yellow – power input; Solid white – left positive; Striped white – left negative; Solid gray – right positive; Striped gray – right negative; Black – ground wire.

On the output side: Blue – remote output/connection to amplifier.

Step 2: Find your car’s wiring or connector diagram to help you identify the matching cables from the LOC to the wiring harness. Cars have varying wiring harness configuration. Once each wire is identified, you are now ready to splice matching wires together.

Step 3: To splice wires together, we’ll use the left positive wire as an example. Cut the left positive wire of the wiring harness in half.

You now have 2 wire ends from the wiring harness and another from the LOC. Remove some of the plastic insulation from all 3 wires using a wire stripper.

Step 4: Take 1 of the wiring harness’ left positive wire and put it beside the left positive wire from the LOC. Twist the matching wires together and you have successfully spliced them.

Step 5: To make sure that the wires are secured, run the spliced wire on one side of an electrical butt connector and crimp it.

Step 6: Remember that we have 3 wires in total, take the other left positive wire of the wiring harness and insert it to the other side of the electrical butt connector earlier. Crimp it and you now have the 3 left positive cables spliced all together.

Step 7: Do these steps to all of the matching cables. Once all are spliced, secure all cables together with electrical tape to ensure strong connection.

Step 8: You may now install the RCA jacks to the LOC output; and it shouldn’t be a problem to connect high level input on amp anymore.

This method is not limited to high level signal radio only. As seen in this video guide, the LOC can be used for a high level input subwoofer.



Is it better to use high level inputs on AMP?

Yes. High-level or speaker level inputs give you better sound for a lower price and less complex installation compared to the traditional RCA cables.

Of course, make sure first that your amplifier-high level input is compatible with each other and that the former can run the higher voltage that will come from the speaker wire.

Misconnecting the high-level amp may cause signal degradation – thus, bad sound output.

Should amp input level be high or low?

High-level input is usually recommended vs low level input. This is especially true since most modern amplifiers can already handle 10 volts at most.

But it still heavily depends on compatibility as some traditional systems cannot support high-level inputs and vice versa.


The radio-amplifier compatibility makes car audio installations and upgrades a little complex. Using high level input on amp, especially traditional ones, will pose risk of component damage.

It’s therefore unsurprising that people associate incompatible components to be the dead end already.

But learning how to wire high level input on amp opens possibilities to upgrade your factory car radio. Get yourself a line output converter and splice your way to an amplified music experience.

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