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previous: Brad Hi all, In your opinion,(in... -- 11/23/1999 12:10 AM

Re: Envelope Follower

11/23/1999 2:48 AM
Mark Hammer	Re: Envelope Follower 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

Re: Envelope Follower

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.

Replies:

Aron Although I have never owned a Mutro... -- 11/23/1999 5:10 AM
Dave James Mark,Thanks for the... -- 11/23/1999 8:22 PM
JD Sleep What about the Craig Anderton Dual ... -- 11/27/1999 3:59 AM