I've got a marshall valvestate 2000 AVT150H. The amp has 4 channels. An acoustic simulator, clean, O.D.1 and O.D. 2; and built into the amp you can hit effects for the 4 channels, there are several options like reverb, noise gate, flanger and so on, but I have to change all that at the amp itself.

So my question is: where should I put my multi effects pedal? Would it be better to run the pedal through the guitar and input on front of amp, or run it through FX LOOP?

  • 2
    Which multi-effects pedal? Does it have its own effects loop? Which effects do you use from the multi-FX? Do you want to use the amp's effects as well?
    – jonrsharpe
    Commented Sep 4, 2014 at 14:29
  • Its a digitech RP90 modeling guitar processor. Im thinking I don't need to use any of my amps effects, because when I put the processor after guitar and b4 amp and I use the marshall foot switch to go to OD1 OR OD2 it sounds really bad. Im fairly new to all of this. Commented Sep 4, 2014 at 23:20
  • No loop on pedal, but the amp has one Commented Sep 5, 2014 at 0:41
  • music.stackexchange.com/q/6214/12202 is also very relevant.
    – jonrsharpe
    Commented Sep 5, 2014 at 8:13

2 Answers 2


The pedal you have (Digitech RP-90) includes amp and cab modelling, so one option would be to ignore the amp's preamp entirely, and run:

Guitar > RP-90 > FX Return > Power Amp

This is the setup suggested by the unit's manual:

mono operation connection diagram from RP-90 user manual

Unfortunately, this means that the complex, multichannel preamp section of your amp ends up not contributing at all - just set it to clean and turn the FX mix all the way up.

The user manual includes the following signal path diagram, which shows the order the different effects are in and where the amp modelling sits:

signal path diagram from RP-90 user manual

Another option is to use only the effects up to and including the amp/distortion block (which you would set to either direct or one of the distortion pedals, not an amp and cab simulator), in the chain:

Guitar > RP-90 > Amp Input > Preamp > Power Amp

Or only the effects after that block, in the chain:

Guitar > Amp Input > Preamp > FX Send > RP-90 > FX Return > Power Amp

These options allow you to get fuller use out of your amp, but limit you* to one half or the other of the effects unit.

* By all means experiment with e.g. wah in the effect loop or reverb before the preamp, but effects generally sound "better" in the order Digitech suggest, particularly as a starting point.

  • 2
    @H.D. Lowrider: Alternatively make sure that the amp and cab simulation are turned off in the effects unit, since that might be causing the crappy sound. Then it should sound better after the guitar an straight into the input of the amp. Commented Sep 5, 2014 at 7:44
  • 2
    @MeaningfulUsername good point, I've just added a section on using the unit before the preamp or in the loop.
    – jonrsharpe
    Commented Sep 5, 2014 at 7:56
  • Im a newbie here, whats all this pre amp and power amp stuff? I thought that the amp was just an amp.could someone please help me with that????? Commented Sep 5, 2014 at 15:27
  • @H.D.Lowrider see e.g. en.wikipedia.org/wiki/Guitar_amplifier#Structure
    – jonrsharpe
    Commented Sep 5, 2014 at 15:31

Depending on the multi effect pedal you have, you can do both. But for the simple case, if you are using distortion from the multi effect, use it connected to your guitar. If you're using only e.g. delay or reverb use it in the loop. If you're using distortion in the amp, it usually sounds better if delay is applied on the overdriven signal, and not on the clean guitar signal. This is achieved by running it in the amp's effects loop.

For the "both" option, check out the 4 cable method.

  • Its a digitech mp90. I haven't figured out the tone I'm looking for yet. I'd like to just run the amp clean and use the pedal for my effects. I am running it after the guitar b4 amp but it sounds like carp on all 4 channels. Commented Sep 5, 2014 at 0:37

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