If you have looked at the rear panel of your guitar combo amp or head and wondered what the effects loop is for, “often abbreviated to FX Loop,” you’re not the first.
Previously, we explored guitar pedals variants and guitar pedal order.
Having covered these topics in previous articles, you could be forgiven for assuming the subject of basic guitar signal chains was done and dusted.
However, another aspect of this discussion leaves many players scratching their heads–guitar amp effects loops.
A guitar effects loop lets you place effects after the amplifier’s preamp stage, but before the power stage. Having your effects applied to the signal after amplification gives you a cleaner and more controlled sound, particularly if you run lots of distortion.
Let’s jump in and find out how you can best utilize effects loops for stage and studio settings.
Origins Of The Effects Loop
The 60s and 70s were much simpler when it came to guitar rigs. The most widely used effects were reverb and tremolo, usually built into the amp.
When a player used external effects units or stompboxes, these units were always fed directly into the amplifier’s input. This signal chain arrangement was mostly acceptable because most commercial amplifiers only ran clean channels.
Players could easily place their modulation and time-based effects before or after distortion, with most amplifiers’ dirt coming exclusively from stompboxes. Depending on which sound players wanted, there was little need for a device such as an FX loop.
As the ’60s morphed into the ’70s, more players began utilizing preamp gain in the quest for an aggressive tone. It was common for players to modify amps such as the Marshall Super Lead for added preamp gain, saturation, and sustained overdrive.
These amplifiers are predecessors to the high-gain amplifiers that would dominate during the 1980s.
While the increase in dirty preamps was significant for the blossoming hard rock and metal movements, running all kinds of stompboxes into a dimed Marshall’s input revealed some problems.
This method worked great for effects such as overdrive and fuzz. However, some players found it provided less desirable results with modulation and time-based effects such as chorus and delay.
This was due to how effects such as delay were altered when run directly into a dirty preamp. Instead of being greeted with clear and clean delay repeats, running delay into distortion resulted in a distorted and muddied echo, which was often unruly.
Some players famously adopted this sound and made great use of it, one of the most notable being Edward Van Halen on the first batch of Van Halen records. Others found this distorted delay almost unusable and sought a solution to this newfound problem.
In 1980, the American amplifier manufacturer Mesa Boogies released the Mark II B model. This amp is credited by many to be the first production amplifier that featured an onboard effects loop.
Understanding effects loops
To understand how an effects loop functions clearly, we must first understand how your guitar or bass amplifier is structured. For now, we will focus on the two main sections of the amp: the preamp and the power amp.
Pre-Amplifier
The preamp increases your guitar pickup’s signal, bringing the signal level up to line level.
Equalization, overdrive, volume, and presence controls are other functions related to your amplifier’s preamp section. These controls help shape the guitar’s tone to the player’s desired sound.
Power-Amplifier
The power amp follows the preamp section, taking the line-level signal produced by the preamp and boosting it to a speaker-level signal.
Distortion
Distortion can be generated from the preamp, power amp, or both. This distortion occurs when either amplifier section is overloaded.
Importantly, it must be noted that the characteristic sounds of preamp and power-amp distortion are different.
If you were to keep the amplifier’s master volume down and turn up the gain, you would hear preamp distortion.
Alternatively, if you were to increase the master volume until you heard an audible breakup, you would hear power amp distortion.
As mentioned, the effects loop allows players to place specific effects between the preamp and power amp sections.
How To Create An Effects Loop
You will need two extra ¼” guitar cables and an amplifier with an FX loop to create an effects loop.
The effects loop will most often be located on the rear panel of your amplifier, with two ¼” jacks labeled SEND and RETURN.
Once located, follow these steps:
- Connect a cable from the SEND output of the effects loop to the first pedal you want to run into your amp’s effects loop.
- Then, from the last pedal in your signal chain, run a cable into the RETURN input of the effects loop.
The rest of your signal chain will remain the same, with a ¼” cable running from the guitar’s output jack to any pedals you DON’T want in the effects loop through to the amplifier’s input jack.
Some effects loops will also feature a DRY/WET knob which you can use to balance how much of the affected signal is blended into your main guitar sound.
What Pedals To Include In An Effects Loop
As with most things about pedal order and signal chain, there are no fast and hard rules regarding what should be run into your effects loop.
However, we can provide some pointers for using them.
- Delay and reverb are both great places to start. Some modulation effects, such as chorus, also benefit from running into an FX Loop.
- Some prefer to run modulation effects such as flanger and phaser into the front of the amplifier. This is due to how prominent the swirling effect of these pedals can become when run into an FX loop.
- Generally, distortion and overdrive pedals produce far better results when run into the front of an amplifier. However, you can experiment using a distortion pedal as a preamp to create a different tone.
You can achieve this effects loop hack by doing the following:
- Run a cable from your guitar’s output jack into the distortion pedal input.
- Run another cable directly into the effects loop RETURN jack from the pedal’s output.
This bypasses the amp’s pre-amplifier, running your distortion pedal directly into the amplifier’s power section.
Different Types Of Effects Loops
There are two different types of effects loops: Series and Parallel.
Series
Series effects loops are the easiest to use; they send the entire signal through the amplifier’s effects loop and back into the amp.
Parallel
Parallel effects loops work differently from Series effects loops in that they split the signal into two separate paths with only one signal being sent into the loop.
Then, a blend control is used to establish how much of either signal you hear through the speaker.
Wrapping Up
Hopefully, we have cleared up the modern enigma that is the amplifier effects loop. Though the loop can seem somewhat complicated at first glance, it is a simple concept that can significantly benefit your guitar tone both on stage and in the studio.
