Looking for a way to make your Multi-FX and Amp sing? Here's our definitive guide to the Mythical 4 cable method and how best to utilise it.

Looking for a way to make your Multi-FX and Amp sing? Here’s our definitive guide to the mythical 4 Cable Method.

gt100 pic

What is it?

Quite simply, it’s a method of using 4 guitar cables to hook up your Multi FX such as a BOSS GT100 to your amplifier.

Why use the 4 Cable Method?

Well, we’ve all hooked up our multi FX in the simplest way, you know the drill…Guitar to “Guitar In”, Left Mono Output to the front-end of an amp, using the Multi FX like a simple pedal board. Maybe a lot of you have used the left output to one amp and the right output to a different amp but the truth is, certain effects just sound better (to the majority of us) when placed before or after the different stages of an amplifier.

If you plug your multi FX in the most standard way, you won’t be able to take advantage of placing certain effects after the Power amp stage of your amp. People who use a multitude of compact/stomp boxes should be well versed in placing some of those FX in the FX loop of their amp in order to take advantage of that, but this can seem a little more tricky when all your effects are inside a impenetrable box!

FX Loop

This is where the wonder of 4 cable method comes into play…

How does it work?

Firstly, your amplifier needs to have an FX loop (and conversely) your multi FX needs a ‘send’ and ‘return’ capability to use this method…Got those? Great! So let’s consider the amplifier.

Amplifiers (in general) have 2 stages that the guitar signal travels through.
The first is called the pre-amp. This stage contains a large proportion of the tonal characteristics of the channel and also the gain level. The sound of pre amp stage obviously differs from amp to amp (think Fender, Marshall, Soldano etc). After the tone has been defined it then needs to be made LOUDER. Taking care of that end of the business is the Power amp stage!

The power amp stage can also affect on the tonal qualities of the sound and there are a ton of interdependencies and variations for components and their interactions…The world of valve/Tube choice is a geeky and bewildering Arena and we won’t dwell on that in this article. We just need to consider that we have a Pre amp stage and a Power amp stage, Okay?

So, in short; The Fx loop on an amp (generally) allows you to place an effect either between those stages or after the power amp stage. In order to make use of you’re Multi FX in this manner you’re going to need an amp with and FX Loop and 4 cables.

Then hook everything up as per this diagram.

4 Cable method


Using a unit like the BOSS GT100, you can easily see the Send and Return points in the internal FX chain, making it easy to figure out which effect you’ve placed pre or Post the amplifier stages. Doing so can help you achieve some awesome results, but it doesn’t just have to be the FX that you move around. How about swapping your Amp’s Pre Amp stage for something completely different? The 4 Cable method and a Multi FX could Help to turn your (albeit amazing) ‘one trick pony’ amplifier into your dream rig.


  • Do you have an amp with an amazing lead channel but less clean ‘head room’ than a tramps wig? Then the 4 Cable method could help to create a great clean tone which bi-passes the Pre-Amp stage of your original Amp and replaces it with a Modelled version of a say the Roland Jazz Chorus.
  • Maybe your amp has the most beautiful, crystalline, chiming wonder-clean channel but has less ‘roar and bite’ than a toothless hamster. Then use the 4 Cable to swap out your Pre Amp Stage with a Fire-Breathing ENGL.

If you own a Multi-FX and use it with an amp that has an FX Loop then you owe it to yourself to give it a try.