Amplifier Effects Loop Basics

FX-Loop Although most Effects Loop send/return jacks are located on the back of an amp, they can also sometimes be found on the front end.

For all of you out there that have gazed in confusion at the Effects Loop (or FX Loop) send and return jacks on your amplifier, we’re going to break down the basics of that often overlooked feature. By the end of this article, you'll fully understand what it's for and why it was a necessary add-on to amps in the first place. And if you happen to use plenty of foot pedals in your setup, there’s a good chance that taking advantage of your amp’s effects loop will improve your tone.

Simply put, the effects loop section allows you to add effects between the preamp/eq and the power amp section of your amplifier as opposed to running everything straight into the front like you would a guitar signal. This is important and sometimes necessary for a few reasons.

Why We Need It

As a rule of thumb, most guitarists like to place their time-based and modulation effects (such as delays, reverbs, chorus and phase pedals) after any type of distortion on their effects signal chain. The general consensus is that those effects tend to sound more natural when the signal is already overdriven. If they were to be placed before distortion, it could cloud out the sound or in the case of delay, completely wash it out. If you’re using pedals to overdrive your sound, you can always manually arrange your pedals to prevent this – but what if you want to use your amp’s internal preamp stage for distortion?

It used to be that the only way to insert effects into an amplifier was through the front end. While this setup was a non-issue for guitarists running overdrive effects, compressors or simply playing clean, it presented a problem for those using time-based or modulation effects if they wanted to take advantage of their amp’s overdrive. Manufacturers were well aware of this problem and so introduced the effects loop send and return jacks – allowing players to once again place effects after overdrive.

Types of Effects Loops

There are a few different types of effects loops but the two most common that you’ll most likely run across are series loops and parallel loops. The first and most basic form of the effects loops is the series loop. In a series loop, the entire signal is interrupted between the input and output jacks or, in the case of the amp itself, between the preamp and power amp stages. This means that the effects are applied to the entire signal. While a series loop works great for a lot guitarists, it should be said that it doesn’t yield the most transparent sound depending on what effects are used.

On the other hand, parallel loops divide the signal, allowing the original signal to go through the loop and remain in the amplifier. Most amps that feature parallel loop also have a blend control which allows you to dial in your preferred amount of effect in the signal. If your amp feature parallel looping, it’s a good idea to set your effects in that loop to 100% wet. Because the dry signal remains in a parallel loop and you have the ability to blend the two signals, having the effects below 100%  will unnecessarily dilute their strength and can cause them to sound weak or faint. Some processors and digital effects have a “kill-dry” option in order to alleviate this problem.

Is it Right for You?

Not every guitarist needs an effects loop feature on their amp. If you happen to keep things simple and stick with distortion, overdrive, compressor pedals or simply play clean, chances are you’ll make little use of an effects loop. But if you happen to have a killer amp with overdrive that just has to be heard but you don’t want your delay, chorus or phaser to get blurred out, an effects loop can certainly save the day.

One thought on “Amplifier Effects Loop Basics”

  • John Pratt

    Thank you for your timely and useful article. Now I understand that I have a parallel loop on my Laney 1x12. it seems like the built in reverb in the amp is part of the parallel loop. Is this possible?

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