How to fx loop

What is an Amplifier FX Loop?

In the world of electric guitars and bass guitars, "FX loop" is a term you'll frequently encounter when discussing amplifiers. An FX loop, short for effects loop, is a specific feature found on many guitar and bass amplifiers that allows you to integrate external audio effects processors into the signal chain of your amplifier in a unique way. Instead of running all your effects pedals into the front of the amplifier, the FX loop provides a designated point to insert them between the amplifier's preamp section and its power amp section.

Understanding Amplifier Signal Chains

To fully grasp the benefit of an FX loop, it's helpful to understand the basic signal path of a typical amplifier. The signal from your instrument first goes through the preamp. The preamp is responsible for shaping the core tone of your instrument, controlling things like gain (overdrive/distortion), EQ (bass, mid, treble), and volume. After the preamp stage, the signal is sent to the power amp. The power amp takes this processed signal and boosts its power to a level sufficient to drive the speaker and produce sound. The speaker then translates this amplified electrical signal into audible sound waves.

How the FX Loop Works

An FX loop typically consists of two jacks: a 'send' and a 'return'.

• Send: This jack acts as an output from the amplifier's preamp section, just before the signal hits the power amp. You connect a cable from the 'send' jack to the input of your effects pedal or processor.
• Return: This jack acts as an input back into the amplifier, specifically into the power amp section. The output of your effects pedal or processor connects to the 'return' jack.

When you use the FX loop, your instrument's signal travels through the preamp, then goes out the 'send' jack, through your chosen effects, and then returns via the 'return' jack directly into the power amp. This bypasses the preamp's gain stages for the effects themselves, which can be a significant advantage.

Benefits of Using an FX Loop

The primary benefits of using an FX loop revolve around signal integrity and the type of effects you're using:

Cleaner Tone and Reduced Noise

Many amplifiers, especially those with high-gain preamps, can introduce a significant amount of noise or unwanted distortion. By placing certain effects, particularly time-based effects like delay, reverb, and chorus, in the FX loop, you can prevent them from being further amplified or distorted by the preamp's gain stages. This results in a cleaner, clearer sound for these effects. Furthermore, the FX loop often provides a cleaner signal path, meaning that if your effects pedals are noisy, their noise will be amplified less than if they were placed in front of the preamp.

Optimal Placement for Time-Based and Modulation Effects

Effects that modify the "space" or "movement" of your sound, such as reverb, delay, chorus, phaser, and flanger, often sound most natural and musically pleasing when placed after the preamp. This is because they are designed to process the "finished" tone of the amplifier. If you put a delay or reverb pedal in front of a high-gain preamp, the preamp will distort the delayed or reverberated signal, often resulting in a muddy or unintelligible sound. Placing them in the FX loop allows them to process the clean, EQ-shaped signal from the preamp, delivering a much clearer and more defined effect.

Maintaining Amp Distortion

If you rely on your amplifier's built-in overdrive or distortion (i.e., you push the preamp into clipping), using the FX loop can help preserve that character. The signal goes through your amp's preamp, gets distorted, and then the effects in the loop process that already-distorted signal. This is often preferable to putting a distortion pedal in front of the amp, which can sometimes sound fizzy or unnatural when combined with the amp's natural overdrive.

When NOT to Use the FX Loop (or use it differently)

While the FX loop is beneficial for many effects, it's not always the best place for every pedal:

Gain-Based Effects (Overdrive, Distortion, Fuzz)

Many guitarists prefer to place their overdrive, distortion, and fuzz pedals in front of the amplifier, directly into the instrument input. This is because these pedals are designed to interact with the amplifier's input stage and often create a more desirable sound when placed there. Putting a distortion pedal in the FX loop can sometimes result in a harsher, more compressed, or less dynamic tone. However, this is a matter of personal preference, and some players do achieve great results with gain pedals in the loop, especially with very clean amps.

Wah Pedals and Compressors

Wah pedals are dynamic effects that often benefit from the initial signal response. Compressors can also be used effectively both in front of the amp and in the loop, depending on the desired outcome. Many players use compressors at the very beginning of their signal chain (before any amp input) to even out their signal before it hits the preamp.

Types of FX Loops

FX loops can vary in their implementation:

• Series FX Loop: This is the most common type. The entire preamp signal is routed through the loop. All effects in the loop process the full signal.
• Parallel FX Loop: Some amplifiers offer parallel loops. This allows you to blend the processed signal from the loop with the original, unprocessed signal. This can be useful for retaining more of the amp's original character while adding effects. Often, a "mix" or "level" control is provided on the amplifier for parallel loops.
• Buffered vs. Unbuffered: An unbuffered loop passes the signal directly. A buffered loop has a buffer circuit within the loop to help maintain signal strength, which can be beneficial for long cable runs or effects that tend to degrade the signal.

Setting Up Your FX Loop

Using an FX loop is straightforward:

1. Identify the 'send' and 'return' jacks on your amplifier.
2. Connect a patch cable from the 'send' jack to the input of your first effects pedal in the loop.
3. Connect a patch cable from the output of your last effects pedal in the loop to the 'return' jack on your amplifier.
4. If you have multiple pedals in the loop, connect them in series from one pedal's output to the next pedal's input.
5. Ensure your amplifier's FX loop is engaged (some amplifiers have a switch to turn it on/off).

Experimentation is key. The best placement for your effects will depend on your specific amplifier, your chosen effects, and your desired sound. Don't be afraid to try different configurations to find what works best for you.