What is the purpose of this resistor?

[Chugs]

How does the addition of the 2.2K resistor affect the response of the Muff style tone control?

[Taylor]

Here is a simulation. Click here, go to file->import and paste this in:

Code Select Expand

$ 1 5.0E-6 5 50 5.0 50
% 0 28853.998118144256
O 416 112 528 112 0
g 368 240 368 272 0
170 160 112 128 112 3 20.0 1000.0 5.0 0.1
174 368 144 416 80 0 20000.0 0.9950000000000001 tone
r 368 144 224 144 0 6800.0
c 368 144 368 240 0 1.0E-7 0.0
c 224 80 288 80 0 2.2E-8 0.0
r 368 80 368 32 0 6800.0
w 368 32 432 32 0
g 432 32 432 48 0
w 160 112 224 112 0
w 224 112 224 80 0
w 224 112 224 144 0
r 288 80 336 80 0 2200.0
w 336 80 368 80 0
s 288 48 336 48 0 1 false
w 336 80 336 48 0
w 288 80 288 48 0
x 49 32 271 36 0 15 click switch to include/exclude 2k2
x 274 328 587 331 0 12 tone control can be adjusted with "tone" slider on the right
o 2 16 0 34 5.0 9.765625E-5 0 -1 in
o 0 16 0 34 2.5 9.765625E-5 1 -1 out


It seems to have a fairly subtle effect on the high end. Cuts freqs above 2khz by 3db when the tone control is on the highpass filter side. If you think of a standard onboard guitar tone pot, where you have a cap to ground, and the pot is acting like a variable resistance in series with this cap, it's kind of the same - limit the flow of the signal through the highpass filter side to tame the highs a little.

[km-r]

i dont know for sure but i think it forms as a voltage divider workign in conjuction with the 22n high pass capacitor to create a sort of attenuation?

[Chugs]

What program is the simulation data for?

[Taylor]

What program is the simulation data for?

Facepalm on my part. It's way past my bed time.

Here is a simulation. Click here, go to file->import and paste this in:

Code Select Expand

$ 1 5.0E-6 5 50 5.0 50
% 0 28853.998118144256
O 416 112 528 112 0
g 368 240 368 272 0
170 160 112 128 112 3 20.0 1000.0 5.0 0.1
174 368 144 416 80 0 20000.0 0.9950000000000001 tone
r 368 144 224 144 0 6800.0
c 368 144 368 240 0 1.0E-7 0.0
c 224 80 288 80 0 2.2E-8 0.0
r 368 80 368 32 0 6800.0
w 368 32 432 32 0
g 432 32 432 48 0
w 160 112 224 112 0
w 224 112 224 80 0
w 224 112 224 144 0
r 288 80 336 80 0 2200.0
w 336 80 368 80 0
s 288 48 336 48 0 1 false
w 336 80 336 48 0
w 288 80 288 48 0
x 49 32 271 36 0 15 click switch to include/exclude 2k2
x 274 328 587 331 0 12 tone control can be adjusted with "tone" slider on the right
o 2 16 0 34 5.0 9.765625E-5 0 -1 in
o 0 16 0 34 2.5 9.765625E-5 1 -1 out


[Projectile]

When you see a resistor in series with a cap in a filter circuit it usually adds some kind of shelf in the response.

[Processaurus]

It makes that side (the treble side/the hi-pass side) of the tone control quieter, to match the volume of the bass side better.  It just makes a regular voltage divider with the 6.8K resistor.

When you see a resistor in series with a cap in a filter circuit it usually adds some kind of shelf in the response.

If you wanted to make a shelving thing with that side of the tone control, to let bass through, you'd put the resistor in parallel with the 22n cap.  Less resistance = less attenuation of bass, by sneaking full range signal around the cap, which is filtering out low frequencies.

[Chugs]

Ah, I see. But will not affect the frequency response too? The Ibanez SD-9 has the same tone control.

Apologies if I am being a moron but I can't see where the file menu is to import the simulation data for the Applet. I am on a Mac if that makes a difference?

Also, a related question. What is the purpose of the 2.2K resistor in this tone control?

[teemuk]

Also, a related question. What is the purpose of the 2.2K resistor in this tone control?

"Shelving". The magnitude of treble cut is limited by the resistor.

[km-r]

i think it will not add a shelving effect. you will need a bypass resistor parallel to that capacitor to have ashelving effect.