Calculating tone knobs' frequency range?

[nate433]

Noob question. How can i calculate the range of frequencies that various EQ knobs (Treble, bass, tone, etc) hit. I know the frequency cutoff formula in a vacuum, but not in the context of a pedal. I have a friend asking about the Chela (Talons). I know you can usually just increase or decrease the cap in....parallel (?) with the pot to change the frequency and let more/less bass through. But not what it starts

So like do you add both resistors connected to pin 1 and 3 as well as the pot? What about the one in series with with pin 2. How much does the rest of the circuit influence it or can you just isolate the loop in the IC (for active EQs like in this case)? Does it being active change any variables or just makes sure you don't have volume loss?

What +/- dBs?

Hopefully that makes sense. Trying to wrap my head around more concepts beyond swapping stuff and seeing what happens haha. Thanks!

 

[jimilee]

I do know the higher the cap value, more bass gets through. And for the other, do a search for a parallel resistor calculator. There’s one frequency as well, I don’t know a lot of specifics myself.

 

[BuddytheReow]

TSC in the web

It all depends on the particular circuit and tone stack you're working with. The link I provided is an excellent resource on the various tone stacks out there, their EQ curves as you turn the dials, and how tweaking a resistor/capacitor can change the response.

 

[nate433]

TSC in the web

It all depends on the particular circuit and tone stack you're working with. The link I provided is an excellent resource on the various tone stacks out there, their EQ curves as you turn the dials, and how tweaking a resistor/capacitor can change the response.

Ya I've used this before, but I guess I'm asking so I can figure it out if it doesn't fit into any of those topologies

 

[swyse]

You might enjoy using LTSpice to model circuits if you want to see a graph of what your potential changes would do.

 

[hamerfan]

If you look into classic pedals like rat, ts, muff, Klon etc. you find your data here:

ElectroSmash - Tube Screamer Circuit Analysis

Schematic, JFET Bypass Switching, JFET Switch Operation, Toggle Circuit Operation, True Bypass Alternative,Power Supply, Input Stage, Input Impedance Calculation,Input Buffer Gain Calculation, Clipping Amp

www.electrosmash.com

 

[giovanni]

If you want to do a mathematical analysis you need to calculate the output and input impedance of the stages preceding and following so you can figure out the full frequency response formula and then you can compute the cutoff as a function of the potentiometer position.

 

[Chuck D. Bones]

Running an LTSpice simulation is the quickest and easiest way to see what's going on and how the components interact.

Two things you should know:
1. Picking caps in a Baxandall tone control can be counterintuitive. Example: increasing the cap(s) in the BASS control network can reduce the amount of bass that gets thru.
2. The Talons (Chela) tone stack is shit. Read here to learn what I did to fix it.