How To Use An Effects Loop On A Guitar Amp

How to Use an Effects Loop on a Guitar Amp

Have you ever looked on the back of your favorite tube amplifier and seen two ¼ inch jacks labeled “FX Send” and “FX Return” and wondered – what do these do?

This means that your amplifier has an Effects Loop, and it can be an incredibly useful tool once you know what it does.

In this article we’re going to explain how to use an effects loop on a guitar amplifier and help you decide if it’s a necessary feature for your sound.

What is an Effects Loop?

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To help understand what an effects loop (aka FX Loop) is and what it does, it helps to have a basic understanding of how an amplifier works.

In short, when you play your electric guitar, your pickups “pick up” the sound waves and create a weak electrical signal. This is then sent through your cables to your amplifier, which is typically split into two sections: the preamp and the poweramp.

These two sections flow in series to one another and then send your amplified signal out through your speaker.

The effects loop sits between the preamp and the poweramp sections of your amplifier, and is used to place effects in this part of the amplifier.

How Do You Use an Effects Loop?

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Hooking up effects into your effects loop is really simple.

Start by plugging a ¼” instrument cable into the “Effects Send” (sometimes called Pre-Amp Out) of the loop. Connect the other end of this cable to the Input of your effect.

Then, take another instrument cable and connect the Output of your effect to the “Effects Return” (sometimes called Power-Amp In) and you have a closed loop!


Your effects loop is a Mono signal if you’re using a tube amplifier, so make sure your effects are set to Mono.

However, if you are using an amp modeler in the Effects Loop, you can use effects in stereo.

You may also need to toggle between Line/Instrument level to get the appropriate signal depending on your amp and effects.


Most effects loops are in Series, meaning that the entire signal from your preamp is sent to your effects and returned to the poweramp section, then sent onto the speaker.

However, some amps have a Parallel effects loop. These split your signal in two, sending a dry signal to your poweramp/speaker, and the wet signal to your effects. You can then use a “Blend” knob to blend in dry/wet signal to taste.

Why Would You Use an Effects Loop?

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When tube amps were first getting cranked up in the sixties, guitarists would place all of their effects in front of the amplifier, and this seemed to work for most applications.

However, as guitar has evolved, there are artists that look to combine heavy gain amp tones with atmospheric effects like delay, reverb, and modulation.

The problem is… using these effects in front of a dirty amp can sound chaotic and muddy.

Effects loops help to solve this issue.

They do this by applying the same basic pedal order rules that many of us apply, where time based effects come after distortion. If you are using a heavy gain amp setting, much of this gain/EQ comes from the preamp of your amplifier, which you can think of as like another overdrive pedal.

The effects loop lets you place your time based effects after the distorted signal.

Which Effects Go Into the Effects Loop?

Typically speaking, any time based effects like Delay, Reverb, and Modulation go into your effects loop. Multi-effects pedals are also great for placing in your effects loop.

However, this isn’t a hard rule. You can place any effect into the effects loop, but you are more than likely not going to like the sounds the come from placing an overdrive or fuzz in a loop.

Boosts and compressors can be placed in the loop to help preserve your amp tone, while adding some volume.

How Do Effects Loops Change Your Sound?

Effects Loops should be really transparent and preserve your sound, with minimal changes in volume. Some even have a volume knob, similar to the makeup gain dial on a compressor pedal.

With that in mind, effects loops don’t change your sound. What’s really happening is a result of pedal order and signal routing.

For instance, when you place a distortion pedal before a delay pedal, the distorted signal is getting sampled and repeated afterwards.

However, when this is flipped, the delayed/repeated signals are getting distorted after the fact, which can cause the effect signal to distort. This is typically unwanted.

Putting all of your effects in front of your amp means that your preamp and poweramp are uninterrupted, and the compression and EQ of your preamp is preserved and translated into your time based effects. This is especially true if you have a clean amp.

Benefits of Using Delay Into a Distorted Amplifier

There are times when using a delay pedal into a distorted amp can not only sound great, but it can actually sound better than how it would sound in an effects loop.

Youtuber/Guitar Nerd, Pete Thorn, does a great video explaining how Eddie Van Halen used an EchoPlex Tape Delay into a cranked Marshall back before effects loops were invented and it sounded amazing! (See below)

The key to pulling off this sound comes down to your delay type and settings. Keep the Mix and Repeats low on an Analog or Tape Delay pedal.

The result is a subtle, warm, and compressed delay that rounds out and fits with a bright, high-gain amp perfectly! To learn more about gain I highly recommend reading my what is gain on a guitar amp article.

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Do You Need an Effects Loop?

Now that we know how to use an effects loop on a guitar amp, the question remains: Do you need an Effects Loop?

It comes down to personal preference, but I think you can use this as a general guideline:

If you primarily play with high gain amp tones, and you want to use effects, an Effects Loop can be beneficial.

If you play with clean to edge-of-breakup sounds primarily, then I don’t think an Effects Loop is necessary.

Finally, if you use a mixture of clean and dirty amp tones through the use of a multi-channel amplifier, an Effects Loop is the best way to manage your time based effects across multiple styles of gain.

Further Reading:

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