Long Time Reader - First Time Question (Rangemasters and Tone Controls)

[Timko]

I've been a longtime reader of DIYStompboxes since I got into building in 2016.  I spend most of my time on Madbeans forum, and got into building some complex pedals.  However, this year I've taken a bit of a break from building other's projects (well, except for Dead End FX's Mutron BiPhase, that thing is a beast) and began to focus more on my own projects.  I started building after finding Joe Gore's Tonefiend site.  My 4th build was his Rangemaster, while my 3rd build was his buffer/booster.  I have long thought that these two circuits would be great combined together because I use boosts of some sorts into my amps more than overdrives (I also got in the habit of playing with earplugs as not to go totally deaf).  So earlier this year I began researching having a dual pedal with a rangemaster and a clean boost.

The clean boost is pretty easy for me.  I am going to opt to use Gore's buffer/booster pedal that I already have.  It will have an input buffer with the boost on a footswitch.  I use a true bypass tuner at the front of my rig so I've generally had a buffer in this position somewhere.

The Rangemaster is where I've been researching most of the year.  I build Jon Patton's Fallstaff Overdrive, hoping that would be the sound that I was looking for.  While it's a great circuit, it's not the sound I was looking for.  I then stumbled upon Smallbear Electronics Darlington Rangemaster.  It was around this time that a guy in a Facebook group I'm part of was selling a bunch of cheap PNP germanium parts with gains in the 30s and 40s.  I realized this would be perfect for a Sziklai Darlington pair so I went about designing that circuit.  The circuit has two of the standard controls you'd see on a lot of RMs: A blend knob for the input cap and a boost control that controls the volume and gain structure. 

One of the final controls I want to add is some sort of tone shaping toward the end of the pedal.  Originally I was looking for some sort of "Tilt" EQ system like what I found on Lectric FX's Zerconia Compression (I think the Diamond Compressor has something similar) but I was trying to keep the tone stack in this particular design passive.  I then stumbled upon The Wonderfully Stupid Tone Control (in particular v2) which contains a treble cut and a treble "boost" (I know it's not really a boost as passive circuits can only cut).  This looked like the perfect option for me.  However, the response of the circuit with the values that AMZ recommends starting with aren't as much to my liking.  The article mentions the overall feeling moves from a cut to a boost.  For me, all I can hear is a cut.  I assume I need to select component values that support the Rangemaster's frequencies a little better to achieve the overall sound I'm looking for (that may be an incorrect assumption by the way).

So, with that background, I have a few questions.  I've read about how to calculate frequency cutoffs for simple RC networks.  How do I go about calculating the frequency cutoff with a more complex tone control like the one I'm looking at?  I looked at the Tone Stack Calculator but I didn't see any tone stack that I could use to replicate the one I was trying to use.  Perhaps there's another piece of software I could use to model?

Here's the tone stack I incorporated BTW.  It's after the boost knob in the traditional Rangemaster Topology:

R1=10k, R2=47k, C1=0.022uF and 100k for the tone.  There is no volume pot since the tone circuit is after the boost.

My background is in computer science and mathematics, so being able to understand the math behind these things will be beneficial to me in the long run.  Eventually I plan to try this circuit with an active tone control like a Baxandall mid boost or event some sort of resonant VCF, but for now, I want to get a version working with this passive control.

Thanks!

[PRR]

Take out the cap. Simple voltage divider. This gives the DC-Bass response.

Note the cap goes top to bottom of the 100k. Draw it both ways. The DC-Bass response is unchanged. The treble response can be sketched by inspection.




Cheating would be LTSpice or similar general simulator.

[Timko]

Thanks!  I think LTspace is exactly what I was looking for.