Mutantes' 6 fuzzes for 6 strings: why?

[barret77]

Hello all

The mythical Mutantes' golden guitar had a "holy pickup" that I have no idea what's about, piezo on the bridge and a hex pickup;
The hex pickup, homemade as the whole guitar, has 6 outputs that connect to 6 independent fuzz circuits, all on board. At least this is what I read/understood - correct me if I'm wrong.

Why?
Does it really make a difference to "fuzz" each string individually?
What does this achieve?

I can't believe I actually held this guitar with my bare hands. It's an awesome instrument! Completely DIY - the metal parts, the body, everything....
I'm not planning to build anything like this, just asking for the sake of understanding.

Thanks a lot!

[R.G.]

Why?

Intermodulation distortion.

Does it really make a difference to "fuzz" each string individually?What does this achieve?

Yes, it does. When you run any two signals through a nonlinear process of any kind, it creates intermodulation distortion.

For a simple example, assume you have two strings producing low E at 82 Hz and a third above it at 5/3 the frequency or 136.7Hz. If you add these and put the resulting signal of (82, 136.7) into a clipping stage, you get out 82 Hz plus its harmonics at  164, 246, 328, etc. and 136.7 plus its harmonics of 273.4, 410.1, 546.8, etc. as well as the intermodulation products: 136.7+/-82 = 54.7 and 218.7, as well as the sum-and-differences of the higher harmonics.

The sum and difference terms are not harmonics of the original tones, nor in fact musically related at all. So it sounds harsh.

However, if you clipped each one separately, then added, you'd get 82 and its harmonics, 136.7 and its harmonics, which are all musically related to the basic tones. It sounds smoother.

[barret77]

nice. I need to try this one day...
Thanks RG!

[Processaurus]

Hair metal bands like the dual lead for that reason, its distorted and its a harmony, but there isn't the dissonance you get playing thirds and sixths on one instrument through heavy distortion.  Thats kind of why most modern music that is heavy generally relies on the power chord, the 1st and 5th notes of a scale produce less intermodulation products.

Roland's old analog guitar synth, the G-303 and the box you plug it into, the GR-300, had an ouptut for hex-fuzz. 

There is a downside, if you had a six channel divided pickup you'd have to make 6 times as many pedal circuits, to process each string seperately.

[WGTP]

The cool thing of it is that you could use a seperate type of distortion for each string, with it's own gain, EQ, etc. Fuzz Face, Tube Screamer, Distorion +, BMP, Vulcan, CMOS, Mu...   

[Mark Hammer]

When Harry Bissell and his wife Dana came up here for a visit several years ago, he brought his homebrew guitar synth with him, and I tried it out for a bit.  It uses a divided pickup he co-opted from one of those G-Vox sets (apparently widely available on E-bay for a decent price).  The individual string pickups went to their own individual Big Muff Pi circuits, believe it or not, though he used voltage-controlled filters for the tone control rather than the normal manual tone control found on a BMP.  Sounded and responded amazing.

The thing about hex systems is that the harmonic richness of chords means you don't really notice differences between strings all that much because they're not fighting each other.  I suppose it *might* be interesting to use different processing or each string, but you turn it into 6 mono sources and lose the capability of having the guitar be a polyphonic source.

[WGTP]

I sort of went overboard, but IMHO some distortions sound better on low's or wound strings and some better on hi's or plain strings.

Didn't the Arp Avatar have a Hex Fuzz???   

[Mark Hammer]

Didn't the Arp Avatar have a Hex Fuzz???

Pretty much ALL non-diital guitar synths have hex fuzzes, if for no other reasons than that they use pickups with small output levels (teeny coils and magnets) which vary in amplitude because of string guage and picking strength.  A comparator circuit (sort of like the Anderton EPFM Ultra-Fuzz)  is almost always used to produce a fixed level for trigger/gate/CV detection.  And naturally, that will be a square wave - le roi des fuzz.

some distortions sound better on low's or wound strings and some better on hi's or plain strings.

Maybe so, but you're thinking in mono signal terms, not hex terms.  In the world of hex, each string's processing is set in accordance with what sounds best for the string, not a compromise about what would be best for strings in general.  When you set the distortion control on a pedal, you have set a clipping threshold which is applied in a uniform manner to all signals coming in, whether from thick or skinny strings.  Maybe what works for high strings don't work so good for low ones.  You're correct there, but with hex each path is "tuned".  If there is any p-to-v conversion, then the lowpass filtering of the fuzz's output is also likely adjusted to provide roughly the same amount of harmonic content for the note played on that string, in comparison to other strings.  It is a convention of synths that the filters track the pitch of the note they happen to be filtering to provide equivalent harmonic content (in terms of % 1st, 2nd, 3rd, etc. harmonic) for all notes.

[petemoore]

  One string sounds like...one string.
  The next string could sound...super freaky [choose your freak to get on].
  Then yet the next string could have like SERIOUS Echo or something.
  Each string having it's own output could also be 'channelled' into it's own amplification system...gangly/extreme/hope you have time to do some dialing and no debugs need be done...but it could be done.

[Mark Hammer]

While all of that is true, the problem is "When was the last time you planned out a single note run that NEVER involved several strings?"

Radically different processing of individual strings ends up being disruptive, like having a remote that randomly switches channels on you in the middle of a game, great concert or steamy movie.  Sure, they're all interesting, and I suppose the "experiment" is interesting in a Stan Brakhage kind of way ( http://www.sensesofcinema.com/contents/directors/02/brakhage.html ) but it's the continuity that becomes fundamental after a little while, not whether what you've switched to is interesting in and of itself.

Note that the string-to-string change is different than something that, say, regularly changed effects in some relatively quick round-robin fashion for a 6-string mono signal, particularly if one had some "magic button" you could keep stepping on to advance to the next different tone.  My sense is that such a system would be considerably less disruptive to one's playing than the different-sound-per-string arrangement because you could plan out a phrase and finish it under the same "sonic umbrella" before switching to the next one.  In contrast, how do you plan out a phrase that needs you to "borrow" an adjacent string for a moment just to finish the riff?

The compromise is to maybe split the instrument so that several different sounds are simultaneously available for combinations of strings.  For example, the E and A have *their* tone, and the other 4 strings share a different but common voicing.  Something like that could conceivably allow one to play phrases and even chords that didn't have to stray outside their physical borders (the one between A and D).

[R.G.]

It makes a great deal of sense to keep the signals separate until they're through the distortion, then mix them back to mono (or stereo if you must) and do the rest of the effects with them combined. That allows you to not hex-uplicate the entire effects chain.

Mark is dead right on the different-sound-per-string. Unless you learned to play each string (or group of strings) as though it were a different instrument, it would be downright confusing. Of course, you may LIKE your sound to be confusing. Mine is almost by definition, so I strive for consistency 

If you wanted to put in the time, you could split groups of strings and deliberately play them as different instruments, kind of a super-close doubleneck. But for me, I don't have the mental skills to stay off X strings while I play one run, then an answering run in ONLY X strings, as a f'rinstance.

[WGTP]

It would be freaky, that is the point.  It's not that hard to play up and down the neck if you know your positions.  Might even want to do some alternative tuning.  That is why I was suggesting maybe using the wound strings for one sound and the plain for another.  That way you only have to worry about limiting your runs to 3 strings. 

I seem to remember a non-synth system that wound the pole of each pickup seperatly and then sent every other string to the left or right side of a stereo system.  Each could be processed differently.   

[H S]

Thats kind of why most modern music that is heavy generally relies on the power chord, the 1st and 5th notes of a scale produce less intermodulation products.

Intermodulation will produce positively musical tones in a power chord.  The 1st and fifth in a power chord will produce a sub octave and an octave-major third.  I.e., 200 Hz and 300Hz will produce the suboctave 100Hz and the octave-major third 500 Hz. 

A distortion with intermodulation can produce some excellent hairy, heavy tones with full chords, too, and leads with some crazy "life" to the tone.  When you play a single note, the overtones of the note itself intermodulate each other.  The difference in frequency between successive overtones is about, but not exactly, the fundamental frequency.  (The difference is caused by friction and string stiffness and the like.)  So the difference frequencies generated by intermodulation don't quite match the fundamental; they cloud around the fundamental and variously interfere with or reinforce it, making it lively.

Vive l'intermodulation!

[Mark Hammer]

I seem to remember a non-synth system that wound the pole of each pickup seperatly and then sent every other string to the left or right side of a stereo system.  Each could be processed differently.   

That would be the Kramer Ripley guitar, as endorsed by EVH for a few years on the back of Guitar Player.  A single hex pickup, wired for stereo-other-string output.  I gather the intent was massive chorus sounds.

Bartolini and a few other people make hex pickups, though do not confuse these with the skinny divided pickups like the GK-1 or the G-Vox pickup.  If you want a synth to respond to one string and not be distracted by others, the pickup has to be snuggled up against the bridge, not up where the string has maximum lateral wiggle.

[toneman]

interesting googling for the "Kramer Ripley guitar".
WOW!   SIX! dual controls!! 
KnobKnightmare or KnobHeaven?  your choice 
thanx Mark!!