Overdrive designs that treat lower and upper registers separately?

[Shoeman]

Anyone know of existing pedals that do something like this?  I'm starting to think up something using pass filters to split the signal and send it to separate processing sections then combine them at the output.   What got me onto the idea was a live Govt Mule song I heard recently where Warren's guitar sounded "moderately" clean on the lower notes but as he went up the neck the notes got a great OD tone.  It caught my ear right away as it really stood out.  One thing I noticed was that low volume difference between the more overdriven notes was not really any louder than the lower notes.   Not what I have experienced with common treble boosters. 
  The trick will be figuring out the filters.  The OD sections can be any of the generic designs just tweaked to the range of frequencies being handled. Then maybe a blend pot at the end or just voltage dividers to set a balance.  Breadboard here I come.
 

[ElectricDruid]

I'm sure I read about a Craig Anderton design that did something like that - split the signal into low and high, distort each separately, add them back together. I'll post something if I can find it.

[Mark Hammer]

It's this:


It's okay.  Not fabulous.  My gripe is that the gain needs to be adjusted for the different bands, given their respective acoustic energy.  Craig set the gain identically for each.  But if the goal is strong control of the tone, it holds up.

The Yamaha MDB-100 also tinkers with the idea, but doesn't provide enough control:


I tinkered with a 2-band approach, that was okay, and certainly easier to make, but not inspiring:

[garcho]

there's also this dual band FET overdrive from almost 10 years ago, Blüe Monster, from forumite Bengt:

https://www.diystompboxes.com/smfforum/index.php?topic=99142.msg877443#msg877443

it can be fun to play with gyrators (simulated inductor filters), or full on VCF stuff, although it gets a little more into psychedelic territory

[idy]

+1 on needing to adjust gain for each band. Deafbutpicky's Thrice used three bands of CMOS and is nice. Link to other forum where missing Schematic was reposted:

https://www.freestompboxes.org/viewtopic.php?f=10&t=25632&p=246874&hilit=deafbutpicky&sid=9457146260f1ff0f4053690cefb81345#p246874

I think when I tried this I also added separate volume for each band. If your'e going to adjust gain, better do volume too.

Easy enough experiment for two bands to use a splitter mixer and "any" two distortion boxes with "any" tone controls.

[Fender3D]

Another pedal, dealing with 2 band distortion, though not "crossovered" like the examples above, is old MXR Distortion II

[Mark Hammer]

There are different goals of using multi-band clipping.

One, which Anderton/PAiA explored is to reduce intermodulation distortion, such that the focus is squarely on harmonic distortion.  Applying gain to narrow individual-band clipping circuits reduces intermodulation.

Another goal is to be able to apply clipping more evenly across the fretboard.  Or, its complement, applying it differentially.

A third goal is to be able to extract very different sounding tones by control of individual bands.

[ElectricDruid]

It's this:


It's okay.  Not fabulous.  My gripe is that the gain needs to be adjusted for the different bands, given their respective acoustic energy.  Craig set the gain identically for each.  But if the goal is strong control of the tone, it holds up.

The Yamaha MDB-100 also tinkers with the idea, but doesn't provide enough control:


I tinkered with a 2-band approach, that was okay, and certainly easier to make, but not inspiring:

Aha! Thanks Mark! That saves me racking my brains trying to remember it! It was that!

That Flexidrive design looks like a lot of time was spent on tone control values *all over* the circuit! Looks like evidence of a lot of tweaking to me.

[R.G.]

In a similar vein, but with a hefty dose of "too much is not enough"     I'm working with a friend on an adjunct to his son's mic'd flute. For background, in the 1970s I did a lot of thought about extracting frequencies in bands from a guitar signal and processing them similarly or differently. Built a few of the filter bands, and largely abandoned it for a few decades.
Along comes Friend A, who wants to extract the fundamental of a flute and synthesize accompaniment for it. I pointed him to the Harmony Generator from E&MM, but that wasn't quite enough for him. We talked and over time he talked me into ressurecting some of the ideas.
The final implementation owes a lot to Rod Elliot's Real Time Audio analyzer design. I ... um, adapted...  the filter circuits, as it was simply too easy not to. I put an SSM2166 compressor, five 1/3-octave filters, five envelope extractors, and five "I got signal!!" detectors along with an FPGA implementation of the MK50240 top octave generator and a PLL to lock the TOG to a fundamental in an equally tempered notes way onto one PCB. The board is 3.9" square. The full implementation uses two boards stacked to get ten 1/3-octave bands to cover the flute fundamental range. Board also contains a priority encoder/selector to pick the lowest-frequency filter output, which is, presumably the fundamental, at least for flute.

It's a busy design. It's all SMD, with TSSOP ICs and 0603 Rs and Cs. More about it if you're interested. As an offshoot, I got the TOG circuit on a two layer board that plugs into the footprint of the actual MK50240. It's not a drop in, as it has to run from 3.3V, not 10 or 12.

[Mark Hammer]

Thanks, Tom.  Yeah, I took advantage of every possible locus in the circuit to keep the top and bottom separate; not just prior to clipping, but after as well.  I was aiming for simplicity by making the gain control reciprocal (i.e., more gain for the one side = less gain for the other).  But in retrospect, separate Gain controls for each channel would have been smarter.  Less elegant, but better control.  Alternatively, perhaps a parallel resistor or two on one or even both legs of the drive/gain pot might yield a smoother transition in the individual gains.  I just used a linear pot, crossed my fingers and hoped it would work out.  There's more gain on tap for the mids+highs section, courtesy of R16 vs R8, but that really only enters into the equation as one approaches the treble end of the drive-balance pot.  As can be the case with many things, pot taper can be critical.

[Shoeman]

Wow!  Thanks for all the input guys.  Keep it coming.  Mark, I now recall see the Flexidrive previously.  I may start there as it's certainly a simpler design than the Anderton.    Sadly all the other links folks posted come back as dead as far as schematics and soundclips go.
Idy,  I had though of your idea of a splitter mixer with two pedals as a basic start to see what gives.  As others have pointed out there might be phase and IM issues but it's an easy "toe in the water" so to speak. 
Researching W. Haynes rig after my initial post shoes a handful of known pedals.  Klon and a Diaz Texas Ranger are the two that I think might be the source of the tone, but I have not played either so I have no idea.  He also runs multiple amps simultaneously through a Bradshaw rig...  so who knows.   Still a worthwhile project I think.  Might not payoff but I'll never know unless I try.

[Radical CJ]

I've had the idea of doing this as a way of useing up all all 6 inverters in a cd4069, LP would go through a soft clip, and HP through a hard clip, then the two would mix via a "tone knob".

[caspercody]

How about the Malekko Wolftone Sloika pedal

[mozz]

 I think there was something with a stereo pedal, that sent the lows to 1 amp and mids/highs to another. So as you played up the fretboard, the sound would appear to move to the second amp. Maybe it was in a dream, not sure ...lol. Maybe make it so rhythms and chords came out of both and as you dug in or turned up the gain the separation would increase.

[mdcmdcmdc]

A couple other examples of the idea from INFANEM.

[amptramp]

This may be a little more complicated than it needs to be.  The Big Muff overdrives use capacitive coupling through antiparallel diodes in a transistor feedback stage to get isolation of low-frequency signals from the diodes to a greater extent than high-frequency signals.

For another approach, you could use a state variable filter with high, low and midrange frequency outputs and only apply distortion to the midrange.  The lows would get too muddy if they were clipped and the highs would get additional unnecessary harmonic content, so if you just apply distortion to the mids, the world becomes a better place.

[soggybag]

VFE Makes a pedal called Triumverate. This splits the signal into three bands and let's you set the drive and mix of each band. It's a lot like the the Quadra Fuzz but three instead of four bands. You can get this as a DIY project.

[marcelomd]

Darkglass X splits the signal in two, with separate Hof and left. There's a compressor on the low side and a drive on the high side.

[bluebunny]

Nothing much to add, just a "+1" from me for Bengt's Blüe Mönstër.  Thanks Gary for posting the link - saves me searching for it! 

[Vivek]

How about the Malekko Wolftone Sloika pedal

Thanks Rob, this is new to me

https://www.youtube.com/watch?v=ov3xz20inlM

Sounds interesting.

I will study it deeper