Block Logo Envelope made perfect!

In 2017 we finally finished our high-quality circuit board to make more of these, with a better layout and cleaner build than before. We previously made 100 using real New Old Stock (NOS) MXR circuit boards for original sounds, but we added the third knob and toggle switch so you could get more tones. The UP/DOWN toggle allows those Mutron type reverse Wah sounds. The EMPHasis knob allows more or less extreme tones. The new board is the same circuit but should be a higher quality built pedal. Also we added LED, True bypass, and 9vDC power jack of course. Very easy to use, unlike many envelope filters which are difficult to set for easy triggering. SIZE : 2 5/16" x 4 5/16", original MXR size 1290 / 1590B enclosure. Uses normal 9Vdc power or battery, very little power, well under 10mA. Get your funk on!! This pedal is not as "synth filtery" sounding as the Mu-Tron, maybe more like an auto wah. Below is one original MXR along with three of our first versions in various stages of build:

As usual, we do a little tweaking to make the pedal more usable. We put a blue trimpot inside on the circuit board, so you can adjust the envelope for different guitars.
Turned all the way up (clockwise) it's exactly the same as the old MXR and works great with weaker pickups like single coils. We normally set it turned down a bit, vertical, to work better for humbuckers or allow a deeper sound with single coils. You can turn it down further to get lower frequencies, even sort of "sub-bass" frequencies that are cool on bass guitar!

Works fine into dirt pedals, even a germanium Fuzz like our NKT Sun Face, as it's output impedance is fuzz-friendly.

BASS GUITAR : With the toggle UP and all knobs at noon, it sounds good on bass. You still hear the low end and normal note, like a clean blend, with the envelope filter sound on top of it. You can use the internal trimpot with the toggle UP to get some deep, cool sounds. With toggle DOWN on bass, you get a more intense effect without as much of the normal sound.

We interviewed Keith Barr (RIP), president and designer for MXR back in the day for our book, and he said this pedal was his favorite, most special design. He said:

That's the one I really wanted people to make comments about. The objective for the Envelope Filter was to produce a box that did it all with digital circuitry (logic chips, used in a non-digital way - AM).

And I gotta say, of all the boxes, I think from a design perspective, that one's the coolest. That's something that somebody ought to write a little article about and say, Look at how cool this design is.

Most people would say, okay you want to make a filter of some sort, and you want it to be sweepable; okay you need some voltage controlled amplifiers, 3080s or something like that; or maybe FETs, or maybe optoisolators or something. Yeah okay, we'll settle down and make our little filter, and we'll make a little detector, and we'll make the detector drive the filter control voltage, and then we're done. No, no, no, I wanted to do it without using any of those things... a whole new way of doing it, completely off the wall. That was the challenge, and I was so pleased with the result because it just worked beautifully. Take a look at the schematic, and if you don't get the electronics, hand it to somebody you think does and ask them what's going on. That is a cool box. You can also put in your book, I'm really let down that nobody who gets electricity that ever looked at that schematic ever thought, Wow that's really cool, I gotta go call Keith and tell him so. (Laughs.)

Specs

• True bypass
• 9vDC power under 10mA 
• SIZE : 2 5/16" x 4 5/16"