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Vintage threads from the first ten years

Envelope Follower

11/23/1999 12:10 AM
Brad	Envelope Follower Hi all, In your opinion,(in 1000 words or less ,what do you consider to be the best envelope follower to build, and would you supply a link to the schematics, please? Thank you, Brad

11/23/1999 2:48 AM
Mark Hammer	Not to be picky, but precise terminology will always get you farther in life. An "envelope follower" is simply a circuit, or circuit fragment that generates a relatively smooth DC voltage which corresponds to the average signal level. Safe to assume that what you mean is an envelope-controlled wah? If the answer to the latter is "Yes", many would probably point their finger at the Mutron III, which now exists in two incarnations: the Neutron (a clone available via GEOFEX), and the Q-Tron/Q-Tron+, which is EH's re-issue/upgrade. The Mutron stands out because of its ability to sweep down as well as up (up is more common), and its ability to produce low-pass, bandpass, or highpass output. The Mutron III was designed by Mike Biegel, who also designed the Biegel Sound Labs Envelope Controlled Filter, which a more select group of folks would argue is the holy grail of this class of devices since it has more bells and whistles, such as independently variable attack and decay times. It's a rack mount unit. I've never seen a schematic of it, and never seen the thing except in reviews and pictures. Other contenders include the EH Dr.Q, Baseballs, Zipper, Y-Triggered Filter, the PAiA Motion Filter, Ibanez Auto-Wah, Univox Funky Filter, MXR Envelope Filter, and BOSS T-Wah and Dynamic Filter. Of the older EH units, only the Baseballs is in production. Given that it encompasses two Dr.Q circuits tuned an octave or so apart, it makes an acceptable substitute for the extinct Dr. Q. The PAiA Motion Filter also works the same way as the Dr. Q, and has a bit more control. The Funky Filter is essentially a Mutron, with maybe a few component differences. I had one 20 years ago, liked it, and miss it. Never seen one since. The MXR unit is my second choice. VERY warm and predictable in a good way. I've passed around a schematic to a few folks but I can't vouch to its accuracy and it would be a bugger to troubleshoot if you didn't know what you were doing. The Ibanez and BOSS units are decent, but not ragged enough for some tastes. I know of no place where the schematics for these units are posted. The Mutron III and EH units can be found at Aron Nelson's web-site, Jack Orman's, RG Keen's, and probably a few others. The thing to understand about envelope-controlled filters is that much of what people like about one unit vs another concerns: a) the attack characteristics, b) the sweep range, c) the resonance, d) the tweakability. In many respects, if you have the schematics, you can often fiddle with a, b, and c, which also accomplishes d. The only thing you really can't simulate about one unit in another one is the class or category of filter.

11/23/1999 2:48 AM

Mark Hammer

Not to be picky, but precise terminology will always get you farther in life. An "envelope follower" is simply a circuit, or circuit fragment that generates a relatively smooth DC voltage which corresponds to the average signal level. Safe to assume that what you mean is an envelope-controlled wah?

If the answer to the latter is "Yes", many would probably point their finger at the Mutron III, which now exists in two incarnations: the Neutron (a clone available via GEOFEX), and the Q-Tron/Q-Tron+, which is EH's re-issue/upgrade. The Mutron stands out because of its ability to sweep down as well as up (up is more common), and its ability to produce low-pass, bandpass, or highpass output.

The Mutron III was designed by Mike Biegel, who also designed the Biegel Sound Labs Envelope Controlled Filter, which a more select group of folks would argue is the holy grail of this class of devices since it has more bells and whistles, such as independently variable attack and decay times. It's a rack mount unit. I've never seen a schematic of it, and never seen the thing except in reviews and pictures.

Other contenders include the EH Dr.Q, Baseballs, Zipper, Y-Triggered Filter, the PAiA Motion Filter, Ibanez Auto-Wah, Univox Funky Filter, MXR Envelope Filter, and BOSS T-Wah and Dynamic Filter. Of the older EH units, only the Baseballs is in production. Given that it encompasses two Dr.Q circuits tuned an octave or so apart, it makes an acceptable substitute for the extinct Dr. Q. The PAiA Motion Filter also works the same way as the Dr. Q, and has a bit more control. The Funky Filter is essentially a Mutron, with maybe a few component differences. I had one 20 years ago, liked it, and miss it. Never seen one since. The MXR unit is my second choice. VERY warm and predictable in a good way. I've passed around a schematic to a few folks but I can't vouch to its accuracy and it would be a bugger to troubleshoot if you didn't know what you were doing. The Ibanez and BOSS units are decent, but not ragged enough for some tastes. I know of no place where the schematics for these units are posted. The Mutron III and EH units can be found at Aron Nelson's web-site, Jack Orman's, RG Keen's, and probably a few others.

The thing to understand about envelope-controlled filters is that much of what people like about one unit vs another concerns: a) the attack characteristics, b) the sweep range, c) the resonance, d) the tweakability. In many respects, if you have the schematics, you can often fiddle with a, b, and c, which also accomplishes d. The only thing you really can't simulate about one unit in another one is the class or category of filter.

11/23/1999 5:10 AM
Aron	Although I have never owned a Mutron III, when WILL I pick up R.G.'s board!!!!???? My vote goes for the Oberheim VCF - Killer and I have one! Believe me when I say this thing is amazing. Aron

11/23/1999 1:54 PM
Mark Hammer	I've seen the movie "7", so I'm not entirely keen on where envy leads you, but I feel a smattering already. Aron, howzabout a brief listing of the features in this puppy? If my gut feel is correct, it probably contains a "real" filter (something more than 12db/octave), and all the features that an analog synth module possesses. I've always wanted to stick a Minimoog filter and envelope detection/control circuitry in a box and see what happened. I suspect this unit probably comes close. Which reminds me. The Moogfooger (sheesh, when will pedal manufacturers stop with the names that almost sound like dirty words/phrases) line of pedals that Big Briar/Bob Moog produces now have a floorbox VCF/ECF. Anybody heard one?

11/23/1999 1:54 PM

Mark Hammer

I've seen the movie "7", so I'm not entirely keen on where envy leads you, but I feel a smattering already.

Aron, howzabout a brief listing of the features in this puppy?

If my gut feel is correct, it probably contains a "real" filter (something more than 12db/octave), and all the features that an analog synth module possesses. I've always wanted to stick a Minimoog filter and envelope detection/control circuitry in a box and see what happened. I suspect this unit probably comes close.

Which reminds me. The Moogfooger (sheesh, when will pedal manufacturers stop with the names that almost sound like dirty words/phrases) line of pedals that Big Briar/Bob Moog produces now have a floorbox VCF/ECF. Anybody heard one?

11/24/1999 4:40 PM
R.G.	Off and on for a while I've been trying to stuff a transistor ladder filter into a board that will go into a 1590BB box. Someday I'll get there.

11/26/1999 5:45 AM
Aron	It doesn't have much really. Just a range knob and a switch that allows you to choose between filter mode and S/H mode. It just happens to sound incredibly good. The S/H stuff is fun and the box itself is cool. It uses 2 batteries and looks like something out of the SEM (synthesizer expander module) line. I remembered how good it sounded in the 70's and I called my friend up and asked him if he still had it. He did and asked me if I wanted it. Heck yeah! I do miss my Mutron Micro V - having traded it. Anyone got the schematic? I guess I'll just build myself a Neutron filter instead. Aron

11/26/1999 5:45 AM

Aron

It doesn't have much really. Just a range knob and a switch that allows you to choose between filter mode and S/H mode. It just happens to sound incredibly good. The S/H stuff is fun and the box itself is cool.

It uses 2 batteries and looks like something out of the SEM (synthesizer expander module) line.

I remembered how good it sounded in the 70's and I called my friend up and asked him if he still had it. He did and asked me if I wanted it. Heck yeah!

I do miss my Mutron Micro V - having traded it. Anyone got the schematic? I guess I'll just build myself a Neutron filter instead.

Aron

11/27/1999 12:32 AM
Mark Hammer	Now this sounds like the one that Frank Zappa was reputed to use, since that's the only one I know with sample and hold capabilities. What I'm curious about is what exactly is being sampled and held? I would assume you need a random signal source to sample for the control voltage, and these are generally accompanied by a control to set the sampling rate (i.e., new sample every X-msec) So, does it have input jacks for external control or is this a one-trick pony (but what a great trick)?

11/27/1999 12:32 AM

Mark Hammer

Now this sounds like the one that Frank Zappa was reputed to use, since that's the only one I know with sample and hold capabilities. What I'm curious about is what exactly is being sampled and held? I would assume you need a random signal source to sample for the control voltage, and these are generally accompanied by a control to set the sampling rate (i.e., new sample every X-msec)

So, does it have input jacks for external control or is this a one-trick pony (but what a great trick)?

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