John Frusciante’s Moog Moogerfooger MF-101 Low Pass Filteraccess_time First seen circa 2005
This pedal is most notably heard on Dani California during the second part of each verse (basically, that “wobbly” sound you hear starting from around 0:45).
Worth noting is that during the studio recording of the song, it seems that John had a bit more complicated setup than what he used on stage:
Frusciante uses the audio from the tape to trigger an envelope generator or ADSR in his modular synthesizer. The envelope generator responds to the playing dynamics and uses that information to dynamically control aJohn Frusciante – Dani California (Part 1)
low-pass filter. Unlike typical auto-Wah, this arrangement allows them to produce considerably more complex filter effects than simple Wah sounds.
In case you’re familiar with the pedal, and how any of this stuff works (since I’m honestly not), be sure to either email me or leave a comment below.
Regarding stage use, it seems likely that John had the MF-101 Low Pass Filter hooked up to a Moog CP-251 Control Processor, which has an LFO control. Based on this YouTube tutorial (How to get the Dani California Filter Effect – 3 Ways – The Frusciante Way Ep. 5), that seems to result in a pretty spot-on tone.
Lastly, in case you want to get a pedal that will get you close to Frusciante’s sound on Dani California, and don’t want to spend a fortune on a Moog, perhaps the best option is the Line 6 FM4 Filter Modeler. John used this pedal himself (albeit for other purposes), and it seems that Josh Klinghoffer nowadays actually uses it himself when playing Dani California live.