Emulating the Mu-Tron III Envelope Filter in the Axe-Fx II and FX-8

iaresee

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As with too many things in my musical life, this one is again driven by Trey Anastasio's recent uptake of this wonderful filter pedal. He used it during the Fare Thee Well shows with the remaining Dead members because Jerry Garcia was a big fan of it and I guess he liked it so much it' stuck around for the 2015 summer Phish tour rig.

The Mu-Tron III is a filter pedal where the center frequency of the filter block is controlled by how hard or soft you pluck the strings -- it's envelope controlled. It has a bunch of knobs and switches to control it's behaviour.

In the Phish sounds Trey is using the Mu-Tron III in reverse, high pass filter mode. So the pedal starts out as a high pass filter with a really high center frequency, essentially passing only the highest of high sounds, and then as you play harder the filter "opens up" and pass more and more low frequency content the hard you play. This gives it this cool, almost synth like sound, with a slight volume swell type thing happening when you pluck notes as the energy difference between the only-high and fuller-range content is considerable. It's really cool.

It sounds like this:



To build this up in the Axe-Fx II (or the FX-8) you're going to start with a filter block. Set it to highpass type. The gain can stay at 0 dB. The Q we want to bump up. I had the best results around 1.819 or so, but use your ears and your own guitar and playing style to tune the Q value to your liking. This is something you can't readily do with the Mu-Tron III pedal -- tailoring it at this depth would require cracking the pedal open and futzing with analog components in the circuit. Something that isn't easy or quick. With the Fractal products: NO PROBLEM! It's one of the things I love about them!

Screen%20Shot%202015-08-02%20at%209.40.32%20PM.png


For the Frequency setting, we're going to right-click on the dial and assign it to a controller. In this instance we're going to use the envelope controller as the source. And we're going to reverse the curve. This means, when the controller is putting out value 0, the filter center frequency is at 20 kHz and when it's putting out value 127 the center frequency is at 73.8 Hz. That's the "reverse" part of this setup. I found it worked fine as a linear curve but I did add some damping, just a touch, to keep it feeling a little less abrupt when the envelope controller values changed.

Screen%20Shot%202015-08-02%20at%209.36.19%20PM.png


For the envelope controller itself, I tuned it to my guitar and playing. You'll need to do this for your own gear, but here's what I had:

Screen%20Shot%202015-08-02%20at%209.35.36%20PM.png


And that's it! Now we've got a funky, synthy reverse high-pass filter thing happening that's totally on par with a Mu-Tron III pedal. No magic really, right? And a lot of fun to play!

Here's the effect block for you from my preset: http://j.mp/1Sz5mQH -- should work with all Axe-Fx II's and the FX-8.

Enjoy!
 

Attachments

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Thanks for the write up. I'll be trying this out. Sounds like a cool addition to the old block library.:encouragement:
 
Play around with the Attack Time on the Envelope Filter. You can find some really cool, interesting settings at higher values. I find the slower attack, at around 30-40 ms, easier to play with than the fast attack shown above (and what I recorded the clip with). You can control it better with finger and pick pressure.
 
Nice Ian! I haven't had a chance to listen to any of the summer tour yet so don't really know how he's using it yet. Will have to check it out. I've been using an envelope-controlled filter block / wah block to get my Mu on... more of the Jerry-style than this effect.

One thing though, it looks like your download link is a text file... ??
 
Nice Ian! I haven't had a chance to listen to any of the summer tour yet so don't really know how he's using it yet. Will have to check it out. I've been using an envelope-controlled filter block / wah block to get my Mu on... more of the Jerry-style than this effect.

He opens it up in the jam on Kill Devil Falls:



One thing though, it looks like your download link is a text file... ??

Just tried it and it comes down as a BLK file for me. It might be text -- it's just a BLK dump from Axe-Edit of the single effects block.
 
Thanks for posting this. I keep an envelope filter in a lot of my presets. Just reversing the curve and cycling through the bandwidths opened up a lot of new options to play with.
 
He opens it up in the jam on Kill Devil Falls:

...

Just tried it and it comes down as a BLK file for me. It might be text -- it's just a BLK dump from Axe-Edit of the single effects block.

I just saved it from the page that opened, and it appeared to work as a BLK. I'll ck it on the Axe when I get a chance. If not, I can just program it from your description.

And yea, I've got that Kill Devil on my watch list ...
 
Btw, thanks for these settings Ian. i now have a filter block for this sound. Yes you do have tweek it to your guitar which i did with really good results!! definitely the sound...
 
Sure, man, i spaced how do i just export the block like you did? thanks
I save it as a block in Axe-Edit and then you can find it in your blocks directory. From there I just push it to Dropbox and publish the public link.

PS: just noticed the filter doesn't do X/Y switching :(
Ha! Yea, I always forget which blocks can and can't do X/Y switching.
 
For anyone having trouble downloading the BLK file from the Dropbox link, I've attached it to the original post above as a post attachment. I'll give up my download tracking with bit.ly for y'all. ;)
 
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