An amp has two main stages. The preamp shapes your tone and, on many amps, creates the distortion. The power amp makes it loud enough to drive the speaker. An effects loop is a pair of jacks, usually labeled Send and Return, that lets you plug pedals in between those two stages.
Why it matters
If your amp is clean and all your dirt comes from pedals, you may not need the loop at all. Everything can go into the front input in the classic order.
The loop earns its place when the amp's preamp provides the distortion. Put a delay into the front of a high-gain channel and the amp distorts every echo, turning it into mush. Put the same delay in the loop and it repeats an already distorted sound, so the echoes stay clear. It's the same "gain first, time effects last" rule, with the amp's preamp acting as one of your drives.
| In front of the amp | In the loop |
|---|---|
| Tuner, wah, compressor | Chorus, phaser, flanger |
| Overdrive, distortion, fuzz, boost | Delay, reverb |
Modulation is flexible. A phaser or a vibe in front can sound great; try both.
The four-cable method
The four-cable method lets one board serve both places. Run guitar to the board, front pedals out to the amp input, amp Send into your loop pedals, and their output back to Return. Many multi-effects units and some switchers are built for this, with dedicated send and return jacks. It's handy for keeping the noise gate around the amp's preamp too.
No loop?
Plenty of great amps have no loop. You have a few options:
- Get your distortion from pedals and keep the amp clean, so everything goes in front.
- Keep the amp's gain moderate so delay and reverb in front still sound clear.
- Use a lower delay mix and fewer repeats on dirty sounds.
- If your rig grows, look at a wet/dry setup: a second clean amp that carries only delay and reverb.
Many classic records were made with delay straight into a cranked amp. If you like the sound, it's right.