What is an effects loop?

[xenor]

What is an effects loop? Why to use one?
I have just bought an amp with and effects send & return but what difference does it make?

[Bizarro]

You can generally run effects in 2 spots, the input section (where you plug in your guitar) and the effects (FX) loop.

To start off, in general amps have two main sections:
1. preamp section, the tone controls change the way this sounds.
2. power amp section, volume knob, amplifies the signal after getting shaped in the preamp section.

Anything run through the input (guitar->FX->amp) means that the effect will be altered by the preamp section before it gets to the power amp section of the amp.

The FX loop takes your guitar signal AFTER it goes through the preamp and runs it into the effects devices and then back to the power amp.

If you have preamp distortion then it'll also distort whatever effect you're running. Sometimes you don't want this, like a delay for example. So an FX loop will allow your tone shaping/distortion to happen and then you can apply the effect after this.

Some high end amps also let you adjust the mix of no-effect signal and FX-altered signal so you can infinitely customize how much of the "effect" you actually hear in relation to the "normal" sound.

Clear as mud?:D

[xenor]

Wow!
Thanks a lot. This really cleared the situation.

[Bizarro]

Glad I could help!

I'm struggling with ordering my effects for my live rig so I've been thinking about this a lot lately! :D

[Bongo Boy]

Also, I've depicted a very simple setup in a sketch in the follwong thread. The picture that shows signal coming from 'AUX SEND' to a reverb unit, then back to 'AUX RETURN' (on the mixer) is such as loop.

http://www.ibreathemusic.com/forums/showthread.php?s=&threadid=3472