Envelope Filter Pedals

I find all the different envelope filter pedals pretty fascinating. Choosing which one to use can be as difficult as finding your perfect dirt pedal.

I don’t have an envelope filter pedal yet. This is the beginning of my research and I figured I would share in case it helps anybody else.

Warning! Filter pedals are in an incredibly deep rabbit hole that fall under the category of Auto-Wah.

The very first envelope filter pedal was the Mu-Tron III from Musitronics Corporation in 1972. Long out of production these vintage pedals now go for $500-$1000+.

In 2014 the original designer of the Mu-Tron III, Mike Beigel, began putting out a variation of this pedal again and now has mu-tron.com and makes the Micro-Tron IV which runs around $279.

Over the years plenty of other companies have come out with clones. Here are a few of the most highly regarded ones.

The next big thing in envelope filters came in 1998 with the Moogerfooger MF-101 from Moog Music. after 20 years in production it’s no longer made. Like the Mu-Tron, a used MF-101 goes for $600-$1000+. A new, in the box, MF-101 is currently going for $1400 on Reverb.

This thing is… crazy cool.
Moog - MF-101 Lowpass Filter - YouTube

Here it is with a drum loop…
Moog MF-101 Demo - YouTube

Clone versions of the MF-101 are a lot harder to come by. The only one I’ve found is this.

Electro Harmonix seems to be the company carrying the envelope filter torch these days. The fact that Mike Beigel (of Mu-Tron fame) did design work for them helps with that.

Where most other companies have one, EHX has five. With the Enigma:Qballs and the Bassballs made spefically for bass.

The MXR M82 Bass Envelope Filter is easily one of the most widely used bass envelope filters. Even people that don’t like it will admit that it’s a good pedal that plays well with other pedals.

Lastly, is the Source Audio Spectrum Inteligent Filter and the C4 Synth. I haven’t looked into these too much because… it’s just overwhelming. As digital effects with a deep application you can use for programming them to do whatever you want, it’s hard to know where to start.

For the Spectrum Intelligent Filter, Gregor (of BassTheWorld.com), who has a Mu-Tron, says he likes the sound of the Spectrum better and with all the extra flexibility it’s an easy replacement to use the Spectrum instead.

For the C4 Synth, I’ve read numerous posts on talkbass.com that said they could use the C4 to do whatever a Moogerfooger MF-101 could do. There was one person that compared seven or eight high end pedals and confirmed this but said the MF-101 still had an organic sound that he couldn’t get with anything else.

If you’re interested in Envelope Filter Pedals take a look at these also. They are all highly regarded.

That’s all I’ve got for now. I’ll add more as I learn more. If you have anything to add, join in. Especially if you’ve found any good comparison videos between different filter pedals. Most of the ones I found only compare the most extreme settings.


@Gio if you still have your Moogerfooger MF-101, would you mind posting some examples of how you use it.

I had read on talkbass.com where a guy talked about adding copper tape shielding to his (and some other minor modification I don’t remember) and uses like a preamp as the foundation of his tone. Having used one, does this make sense to you?

I don’t have a pedal for it but I use envelopes and filters a lot. Mostly on synths - they are the foundation of subtractive synthesis - but also on most of my bass tracks, in some way. Usually as a HPF rather than LPF though. Still, really useful tool.


The C4 can be a bit daunting at first, but after spending some time with it and watching an excellent video shared by @DaveT it all made perfect sense. I have a MF-101 patch programmed, along with many many many others that can take the place of filters, octaves, tremolos, filters, wahs, other Source Audio pedals and a ton more.

If you sit with the C4 and this video it really opens up the possibilities. You can for sure go down the rabbit hole of synths and spend years experimenting and programming the thing, but you also don’t have to. You can grab everyone else’s work online and put it in your pedal and done.

As for the minutia around the C4 missing nuances that the MoogerFooger or other pedals have and it doesn’t….does it matter if you really have no idea what they are? I find these guys are generally deep into pedal geekdom and nothing that really matters to the average beginner (or many others for that matter). This pedal can be controlled by an expression pedal to boot.

C4s can be found used for $200 or less even all the time.

I also have the MXR and basically leave it in the classic funky filter settings so its always there to jam with. These are solid and cheap and plentiful used so even cheaper, and can generally be had for under $100. No expression pedal input here.

And then I have the Iron Ether Xerograph filter as well. Why? Do I need it? No. It is a different take on the filter and does some really odd and wacky stuff. I was intrigued by it watching Josh’s pedalboard tour video. It makes a lot of very cool “chompy” sounds and is a different take on the classic filter, and, it can be controlled by an expression pedal for even more fun.


@howard Are you using any specific emulations of pedals?

@John_E I figured you would chime in on this one. :smiley: :+1:

I agree. Maybe the real thing would be nice for capturing some special nuance when recording but 90%+ is going to be way more than anyone in a bar would ever notice.

Yep, this one has a lot of fans also. There were a bunch of really great pedals I left out of the original post.

Added this to the original post…

If you’re interested in Envelope Filter Pedals take a look at these also. They are all highly regarded.
Iron Ether Xerograph
Aguilar Filter Twin
Emma DiscumBoBulator
Josh Wah
Pigtronix Resotron
SubDecay Prometheus DLX

Gregor reviews the 3Leaf Audio Proton


No, filters are more fundamental than that. They are built in to every synthesizer, usually more than one, and for general use there’s a ton of them as well, but none that I own are really trying to emulate a specific pedal. Some on the synthesizers do try and emulate a specific filter though.

The one I use most with bass is Kilohearts’ filter snapin:

Simple, and does the job nicely. If I want to use it like an envelope filter pedal I would use it inside SnapHeap or Multipass and modulate it with an envelope or LFO (or both).

Like anything else, some people do geek out over filter plugins too, of course.


For me at least, this one is super complicated to dial in, it is very fussy and very noisy.
I shall conquer it someday… one pedal at a time.

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In that neuro app deep dive video he said he was able to get it close to the Moog LF pedal, but hadn’t spent the time to really dial it in. No verdict on how close he was ultimately able to get. Even if pretty darn close, the analogue purist preference will always also exist. He also pointed out that the Moog pedal can be noisy as a trade off. Not to mention that the Moog pedal is way more than double the price of the C4. I almost bought the Moog when it was still in production and now I’m sorry I didn’t.

Because of this thread my C4 arrived last week, but it was intercepted and wrapped for Christmas :joy: so I haven’t played yet.

I’ll probably sell the MXR envelope if this sounds at all funky. I’m really looking forward to the filter frequency tracking the note most of all.

I also ordered the SuperEgo Plus :grimacing:, mostly for the note latch sustain pedal effect.


I downloaded his MF patch. Sounds great to my untrained ears. Hahahah


I’m in the threshold of “sounds cool enough” and “doesn’t stink” category of happiness.


I bought the C4 brand new for $217, and that’s with tax fwiw. Life’s been busy and not had a chance to sit down with it yet, but will do so soon

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I love bass, but other than a bass that plays great, I have paid little to no attention to gear.

So, sadly, this does not make sense to me.
The pedal has a very unavoidable preamp in it, so it’s unavoidable. If you’re using it in line with other pedals, it’s part of your signal.

I use it as a way to make things super funky and Bootsy-esque.
It’s on all the time in conjunction with my MXR sub-octave-bass-fuzz to get a real dirty synth vibe.

Not sure if that helps or not.


The Source Audio Spectrum is exactly the same as the C4 but the main difference is that the knobs have fixed functions while on the C4 you can appoint each knob to different functions.

So if you are planning to only do enveloppe filters the spectrum may be easier but I would get the C4 because it has more community presets. But you can load them on both anyway.

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It does. Thanks @Gio.


Was looking at some old threads and saw this…

I noticed that you also have a Moogerfooger MF-101. I also noticed that, as this board developed, you replaced it with a second Iron Ether Xerograph. Also, you removed the MXR envelope filter.

Would you mind talking about what you were going for that you made all these changes?

I read the Iron Ether Xerograph can get pretty darn close to the MF-101.

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Hey Eric! Yeah, I actually have two MF-101s, I had the foresight to get an extra when they were going out of production. Guess I’ll sit on that a few more years and retire, lol!

However, I swapped it out for the second Xerograph eventually, because -

  • The Moog is huuuuuuuuge and pedalboard real estate is precious
  • The Moog is noissyyyyyyy and the Xerograph isn’t
  • The Xerograph does a very good facsimile of an analog resonant LPF, it was very adequate for my purposes
  • I had two on the board because I need two different sounds and it doesn’t have presets or MIDI in :stuck_out_tongue:

And I love the MXR! Still one of my fav little auto envelope pedals. Just didn’t need it for that particular band, but I still take it out for fun. You can get nice funky wah sounds, but it’ll also do some cool resonance sweepy sh*t if you run fuzz into it :blush:



Josh, any chance you could share settings for this?
I am still not ‘intimate’ with the Xerograph.
So many dials on so many pedals, so little time.

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