If you’ve been a guitarist for more than five minutes, you’re pretty familiar with effects. Effects can morph our plain guitar sound into something from outer space or just make it seem a little bigger than it actually is. There are many different kinds of effects out there, and many theories stating the ‘correct’ order of effects in your Chain of Sonic Domination. One thing everyone can agree on is that eventually, all those effects have to get plugged into an amp. In the old days, when men wore high trousers and suspenders, there was only one way to plug anything in – the singular jack called ‘input’ – and it was good. Amps soon got more sophisticated, and in the back of most modern amps are a pair of jacks which get the title of ‘effects loop.’ For the uninitiated, this article will explain what these jacks are for, and why at least some of your effects should get plugged into them.
I don’t bother with those jacks, they’ll start a fire.
Well no, unless you fill them with gas and light them on fire.* These jacks are insert points between the preamp (the main distortion-producing stage in modern amps) and the power amp, which takes that sound and makes it much, much louder. See, some effects sound especially good going before the preamp. These effects, like compressors, overdrives, Seymour Duncan Dirty Deed Distortion Pedal, wahs, and even phasers, should be plugged into the input of the amp. So the signal chain should be: Guitar>These Effects I Just Listed>Amp.
OK, why should I use those jacks, then?
If you get your distorted sound from the amp itself, and you like effects like chorus, flanger and delay, you will most likely get a clearer, cleaner sound by using these mystery jacks on the back of the amp. The idea is that you plug a cable into the effects loop send jack, into the input of, say, a delay pedal like the Seymour Duncan Vapor Trail Analog Delay. You would then plug the output of the delay into the return of the effects loop. The theory behind all this is if you present an echoed sound to the preamp, the sound will be affected by the compression and distortion that the preamp generates. This sounds muddy and indistinct, as the preamp compresses and distorts every echo while trying to compress and distort your original guitar signal as well. By placing the delay pedal after the preamp instead (in the effects loop), it echoes the already-distorted signal, so your individual repeats are clear and they don’t interfere with your playing. Keep in mind, there are a few different types of effects loops, which I will cover in the next sections.
Serial Effects Loops
These are the most common types of loops, and the ones I have shown in the pictures above. These are a hard detour on the road between the preamp and power amp. Normally, the signal passes straight from the preamp to the poweramp, until something is plugged into the effects send jack. This diverts the entire signal down that cable, through a chorus or delay pedal, and back on the road to the power amp via the effects return jack. Here the balance between the dry, unaffected signal, and the wet modulated signal is set on the pedals themselves, usually with the mix knob on the respective pedals. Since all of the signal from the preamp is being sent to the pedals, make sure that the level you get from the pedals is the same as going to the pedals. Check this by having the effects on, and unplug both jacks on the effects loop. If the volume suddenly jumps either up or down, you will need to balance them by using the mix knobs on your pedals.
Parallel Effects Loops
These are easy to spot, as they usually have a mix knob right next to the effects loop jacks. The idea is that you get to choose how much of the preamp signal gets routed to your effects. Here, when using a delay pedal, you would set the mix to 100% wet, and set the ratio of dry to wet signal with the mix knob on the amp. These amps will preserve more of the ‘amp’ sound, rather than ‘effect’ sound. Since the signal between the preamp and power amp is never broken, you get to mix in as much or as little effect as you want, much like an aux send on a mixer. You can see in the little illustration below how series and parallel loops differ:
Some people don’t want the entire sound of the amp going to their effects, and some people don’t care. It is really up to you to decide how you want to use effects. And remember, the most groundbreaking sounds in music were made by people not following the rules. Just don’t use gas, please.
Do you use the effects loop on your amp? What are your favorite effects to use?
*Don’t do this, as it will start a fire.