Mutron III or the closest thing??

[Evad Nomenclature]

Hey guys.

My buddy has been bugging me since I started doing the diy thing that "you have to make me a Mutron env. filter!!!"

I didn't have any luck finding a PCB layout or anything... I did find some PCB layouts on tonepad and somewhere else for the Maestro Filter and the MXR 440 filter...

So the question is... Which way is the way to go to get the closest thing to the Mutron...?
One of those env filters, or maybe someone has a Mu-tron PCB layout somewhere?
Thanks

[Joe Viau]

Check out the Neutron project at geofex.com.  It's well documented with several options.

[Mark Hammer]

There are some peculiarities of the Mutron II that not many other types of designs (and I'm not talking about clones like the Q-Tron and Neutron) can replicate.  So, the first thing that needs to be established is whether he is referring to "the Mutron" in a kind of generic way as meaning ANY automatically swept filter, or whether he is referring to a very specific feature or tone.  If all he wants is a auto-swept filter, then the Doctor Q and its derivatives (Dr. Quack, Nurse Quacky) provide a low-cost and trouble-free step in that direction, and are amenable to all sorts of interesting and pleasing mods.

[Evad Nomenclature]

Actually, the Mutron III

He's a hippee and wants to have Jerry Garcia's autowah sound from the early/mid 70's ^_^
I figured I'd build it for em for xmas and surprise em.

[petemoore]

http://www.generalguitargadgets.com/index.php?page=shop.product_details&flypage=shop.flypage&product_id=83&category_id=18&option=com_virtuemart&Itemid=45
  Maybe somehow I'll get that board populated before next year !...Not something I'd wanna rush tho, been putting it off for years, really need to get with it. Mutron III replica JD says, fits: 'closest thing'. Looks deluxe to me.

[mdh]

Mark,

There are some peculiarities of the Mutron II that not many other types of designs (and I'm not talking about clones like the Q-Tron and Neutron) can replicate.

Could you clarify this statement?  Are you just saying that the Mutron III/Q-Tron/Neutron share a set of peculiarities that don't show up in other designs?  Because at first I read this to say that the clones can't replicate the originals, which doesn't sound like you.

[chicago_mike]

Mutron III and clones use optoisolators while other designs use a cmos or jfets for the sweep. At least I think its the sweep.

[sockeye]

I've never played or heard a pedal that nails all the Mutron sounds. Or even nails the Mutron settings that Garcia used. I had an original one though, and I'll say it's a pretty finicky pedal and is very sensitive to pickup types, volume knob settings, etc. Garcia used it with an onboard buffered effects loop pre-guitar-volume- knob so that helped in his case. Also, they have a preamp in the pedal which is always on, even in "bypass" mode. I wasn't crazy about the sound of the preamp myself.

I bought mine in 1988 for $75 with the AC power supply. Sold it in the early 90s for something like $200 and thought I was making out like a bandit! I kind of regret selling it, but it really was kind of a PITA.

[chicago_mike]

It sounds the most liquid. Only the old chrome morley wahs got that sound too. with a lightbulb of some kind I think. Very watery and not as quacky.

[Mark Hammer]

Mark,

Could you clarify this statement?  Are you just saying that the Mutron III/Q-Tron/Neutron share a set of peculiarities that don't show up in other designs?  Because at first I read this to say that the clones can't replicate the originals, which doesn't sound like you.

A lot of autowahs use a bandpass filter configuration (where the Mu-tron ha sbandpass, highpass, and lowpass), and lack the up/down sweep of the Mutron and filter Q adjustment.  There is also the slight difference in time constants resulting from the rectifier properties and the properties of the LDRs used, and the range of sweep provided, yielding a different feel.  Finally, the Mu-tron III adjusts the gain of the input section and sensitivity of the sweep circuit at the same time, meaning that the filter sections are driven harder when you crank the sensitivity up.  In many other units, change in the gain of the sweep/rectifier circuit is entirely independent from the input stage.

I'm not suggesting that those differences are: a) impossible to replicate by other means, or to clone, b) noticeable to all users, c) important, d) desirable, e) "better" or worse than other designs.  They're just....there...and if someone wants something that "sounds like" a Mu-tron III, then it might be critical to that person to include those design aspects.  There ARE other pedals that have many of the same performance features (or can be modded to do so), but a slightly different sound resulting from the differences in design noted above.  There are also a LOT of pedals produced under different names and brands that are the autowah equivalent of the "multiple-identities" Univox/Royal/Honey/Shin-Ei Superfuzz of the 60's.  You can find links to them all here: http://filters.muziq.be/model/musitronics/mutron3

[Evad Nomenclature]

Thanks for all the info guys.
I did remember once you mentioned it about how Jerry ran his guitar for some of the effects.  Forgot about that.
I will most definitely check out the Neutron, I have an MXR 440 clone I have been building for the last couple months (been waiting for a futurlec order with the IC's, finally got it in)
I'm gonna finish that env filter and see how it sounds... probably gonna build the FSH and the Neutron as well...
I can always find good homes for them ^_^ whether it be on my growing board or all of the guys that I know trying to scrounge stuff off me.
Thanks again guys and have a good t day.
Dave

[Mark Hammer]

FWIW, I always thought that Jerry Garcia used an MXR Envelope Filter, simply because of the kinds of sounds I heard from him.  That would suggest that there can be some overlap between the tones from those two pedals.

[sockeye]

If I'm not mistaken, the original Musitronics Mutron used an incandescent lightbulb in the optocoupler section. The one that was resissued by HAZ used an LED and did not sound the same. Going on memory here so that may not be correct.

[B Tremblay]

I remember reading somewhere that he used an E-H Zipper at some point.  I probably read it on teh intarwebz, though.

[Mark Hammer]

If I'm not mistaken, the original Musitronics Mutron used an incandescent lightbulb in the optocoupler section. The one that was resissued by HAZ used an LED and did not sound the same. Going on memory here so that may not be correct.

Nope.  The original used a dual optoisolator - two LDRs coupled to one LED.  Keep in mind that incandescent bulbs take too long to reach maximum illumination for some purposes.  LEDs provide the speed that this particular application requires.