Omar Rodríguez-López is the composer, lead guitarist and producer for the progressive rock group The Mars Volta and the former guitarist for the post-hardcore outfit At the Drive-In.

This guy has a pretty extensive guitar rig. He has a ton of effects pedals!

Let's look at some of the gear and equipment that has been seen in Mars Volta's Omar Rodriguez's guitar rig.

Electro-Harmonix HOG

Featured in this November 23, 2017 Premier Guitar interview.

In this photo, which comes from the 2014 Sound on Sound article, Hayward's pedalboard is visible. One of the pedals included is the EHX HOG2.

Drew show's off his mid 2023 pedalboard in this interview, clearly showing a HOG 2. The article implies this is a picture of his international touring rig.

Drew has long used the Hog, and now obviously the Hog 2, having discussed it in much older interviews.

I think it's interesting that he doesn't seem to have either MIDI or the optional Hog 2 foot controller attached. I kinda would've expected him to be running presets, allowing for multiple different sounds, maybe integrated with his AxeFX2. The fact that he doesn't implies to me that the Hog 2 is in WYSIWYG mode, which is to say the settings he has in this screenshot might be the actual settings he uses is songs.

With that in mind, I can see he's using a lot of low harmonics, including a 5th harmony, all which are set to a very slow attack meaning they will fade in slowly over the top of his dry tone. There's also just a touch of 3rd octave up, which is interesting, and won't be effected by the slow attack, it might even have it's decay cut back. He's in Step Bend mode which pends up 1 whole step. There's no expression pedal attached, but he could stand on that center switch to cause a momentary one step bend, though I'm not convinced he actually uses that, especially with his dry mixed in. The filter section is also interesting, he has the resonance set very high, which suggests to me he's using a high q filter to really push a particular high frequency band through the mix.

This is a really awesome, versatile pedal, and I think it speaks volumes for it's importance to Karnivool that Drew drags it all around the world despite it's large size. I'm sure he could replicate some effects like this with his AxeFx2 rig, though I suspect if you asked Drew he would say nothing could replace that Hog.

In a recording session photo for "An End Has a Start," Chris Urbanowicz is seen using the Electro-Harmonix HOG 2 Harmonic Octave Generator. This image is discussed in The Editors' section of the Guitar.com Forum.

Tell us about your pedals

My pedalboard is always in a state of flux, but currently I’m using an Ernie Ball volume pedal for swells and a simple Boss DD-3 for delay. I also have a Boss TR-2 Tremolo pedal and a Boss OC-3 Super Octave pedal, and a Fulltone OCD distortion pedal. For weird sounds, I’ll sometimes use my Electro- Harmonix Harmonic Octave Generator.

In the video by Premier Guitar titled "Linkin Park Rig Rundown with Mike Shinoda, Dave 'Phoenix' Farrell & Alex Feder (Brad Delson)," at the 43:22 mark, Alex Feder's tech team demonstrates a pedalboard setup that includes two Electro-Harmonix HOG 2 Harmonic Octave Generator pedals.

In this photo, which shows Fleet Foxes' performance at KEXP, the EHX HOG2 can be seen in Henderson's pedalboard.

In an Instagram post by @pedalempire, Sam Cromack of Ball Park Music is shown using the Electro-Harmonix HOG 2 Harmonic Octave Generator as part of his pedalboard setup for their upcoming tour.

Hoshiko's Electro-Harmonix HOG 2 can be seen at 0:03 in the video

In an Instagram reel by user @qqwt23, Masahiko Ohno's setup is shown to include the Electro-Harmonix HOG 2 Harmonic Octave Generator.

Alex Davies is shown using the Electro-Harmonix HOG 2 Harmonic Octave Generator in a Facebook post by Elliot Minor, likely for the "Parallel Worlds" solo.