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Why Your Pedalboard Sounds Completely Different in the Effects Loop
Play a chord with your board running straight into the front of your amp. Now flip your delay and reverb into the amp's effects loop and play the same chord, same settings, nothing touched on the pedals themselves. It sounds like a different rig. That difference is what we're getting into today: four cable method, five cable method, and why moving two pedals from the front of your amp to the loop changes so much even when using the same gear.
What four cable method actually is
If you're running a mono board into one amp, you're doing one of two things: everything into the amp's input, or your wet effects (modulation, delay, reverb) routed through the amp's effects loop instead. That second option is four cable method, and it's called that because it takes four instrument leads to wire up.
1. Guitar into your first pedal is cable one.
2. After your last dry effect (overdrive, compression, distortion) into the amp's input is cable two.
3. From the amp's effects send into your first wet pedal is cable three.
2. After your last dry effect (overdrive, compression, distortion) into the amp's input is cable two.
3. From the amp's effects send into your first wet pedal is cable three.
4. From your last pedal, usually a reverb, back into the amp's effects return is cable four.
Four leads, four cable method.
Here's what's actually happening inside the amp. Every amp has a preamp section, where you get your tone, your gain, your channel switching (overdrive) if you have it, and a power amp section. The power amp takes that preamp signal and raises volume and power so it can drive your speakers. When everything runs into the front of the amp, all of your effects, dry and wet, are hitting that preamp before the power amp ever sees them. Four cable method just moves the preamp in with your dry effects. Picture it sitting on your board like another overdrive pedal. Your dry effects feed the preamp, the preamp feeds your modulation and wet effects, and then it's on to the power amp and speaker.
Neither wiring is right or wrong. They're just different, and one will probably suit what you're going for better than the other.
Does your amp support it?
Not every tube amp lets you do this. Every tube amp has a preamp and a power amp, but not every amp gives you the external jacks to split those two sections apart. You're looking for effects send, effects return, or sometimes preamp out and power amp in, usually on the back of the amp, occasionally on top depending on the model. A Vox AC30 typically doesn't have FX Loop jacks. A Mesa Boogie triple rectifier does. Check your amp, or check the spec sheet before you buy one, and you'll know in about ten seconds whether four cable method is even an option.
Quick note on effects loops themselves, since not all of them behave the same: some are passive and struggle with long cable runs, others are buffered and can drive long cables without issue.
Most are series, meaning the whole preamp signal goes out to the FX Send (and feeds your modulation / wet effects). Some are parallel which means they take the preamp signal and split it. Some to your wet effects and some straight to the power amp. This is great for parallel effects and wet dry wet systems. This is not what we're getting into today. Today we're talking about the standard series loop, the one you'll run into most often.
If you're using an amp sim instead of a tube amp, the same logic applies. If your sim has its own effects loop built in, like the ToneKing Imperial we used for the audio in this one, you wire it exactly the same way. If your sim only has a single input and output, something like a Tonex One, you fake it: run your dry effects into the sim, then feed the sim's output into your modulation, delay, and reverb. The one difference is your cab sim now sits before your wet effects instead of after them, which is a small trade-off. The part that actually matters, moving the gain and clipping stage ahead of your modulation and reverb, still happens exactly the same way.
Who actually uses this
Mostly people on channel switching amps, high gain rock and metal players especially, but it's not reserved only for these players. If your amp gives you overdrive from its own preamp and you're also running modulation, delay, and reverb, whatever the genre, it's worth testing. On a clean pedal platform amp the difference is a lot more subtle. Most people running that kind of rig just leave everything up front. On a high gain channel switching amp, it's a different sound, and only testing it on your own rig will tell you which side you land on.
Five cable method: four cable, but stereo
If you like the sound of four cable method but you also want stereo modulation, delay, and reverb, that's five cable method. To run this you'll need another amp.
1. Cable one is guitar into your first pedal, same as before.
2. Cable two runs from your last dry effect into amp one's input.
3. Cable three is the effects send from amp one into your first wet effect, mono in.
4. From there your modulation, delay, and reverb run in stereo, left and right the whole way through. The left output of your last wet pedal goes back into amp one's effects return, that's cable four.
5. The right output goes into a second amp's effects return only, cable five.
That second amp isn't using its preamp signal at all, just a power amp and cab handling one side of the stereo field. Amplifier one's preamp is doing the work for both amps' power sections. One preamp, two power amps and cabs, which is how you end up with a wide stereo image instead of a mono signal split two ways.
The catch: ground loops and phase
Four and five cable method both come with a couple of things you need to be ready to fix if you're relying on this rig for gigs.
Splitting your preamp and power amp into two sections of your board means those two sections can end up seeing a different ground potential, and that can show up as 60 cycle hum, a ground loop. It won't happen on every amp or every stage, but it happens often enough that I'd never build a four or five cable rig without a fix on hand. An audio transformer between your last wet effect and the amp's effects return lifts the ground and solves it. I keep a Buzzkill in the gig bag for exactly this: patch it in near the effects return and the hum is gone.
Five cable method makes ground loops a bit more likely, since now you've got two amps and two mains cables into the wall, and it's venue dependent. You might get a loop at one room and not the next, so plan to have a transformer on hand for both amps' effects returns if you want to be fully covered on every stage. You'll also want the ability to flip polarity on the second amp's effects return, so the two amps aren't cancelling frequencies against each other. That's a rig issue, not a venue issue, so if it's a problem at home it'll be a problem everywhere. Buzzkill handles the polarity flip too.
Four cable method's real downside is smaller: you need an amp built for it, and a couple of extra cables. If your amp has the jacks and you've got the leads, that's about it. Budget an extra minute for setup once you've sorted your ground and polarity fixes, and you're done.
Why they actually sound different
Run everything into the front of the amp and your delay repeats clean up as they get quieter, the same way pulling back your guitar volume cleans up an overdrive. The gain drops, the clipping drops with it. Move your delay and reverb into the loop and that doesn't happen, because those wet effects are being fed by whatever gain and clipping is already happening on your dry side. The repeats and the reverb tail stay driven all the way down, the same way a volume pedal placed after your overdrives keeps the whole sweep clipped no matter where you set it.
Neither one is better. It's what you're chasing in your rig. Try it on your own board, listen to what changes, and let your ears make the call.
I hope this was helpful! Give it a try and let us know how it went for you.
Have fun experimenting.
Grant
Have fun experimenting.
Grant
