Single tone knob question

[HBamps]

Perhaps I'm missing something, but to my eyes the GA30 and Chieftan midrange controls are wired up the same...

ok, my mistake, they are wired the same. I got the GA30 mixed up with some of the Z tone knob schems floating around (like the Stang). Those don't have the open ended pot and seems to scoop out the mids pretty heavily.

When you model the GA30 / cheiften control, try 100k's, there's a little less scoop and shifts it so there's a little more lower mids. may sounds cool, especially if you don't want to loose too much gain.

[dehughes]

ok, my mistake, they are wired the same. I got the GA30 mixed up with some of the Z tone knob schems floating around (like the Stang). Those don't have the open ended pot and seems to scoop out the mids pretty heavily.

When you model the GA30 / cheiften control, try 100k's, there's a little less scoop and shifts it so there's a little more lower mids. may sounds cool, especially if you don't want to loose too much gain.

You're suggesting try 100k resistors in place of the 150k ones? What is happening when I raise or lower their values?

[imaradiostar]

My suggestion would be to replace the 250pf cap with a 500pf- it'll make the mid scoop less pronounced and increase the relative amount of treble in relationship to the bass. The perceived overall effect may be darker though with the increased mids.

Maybe a conjunctive filter isn't the correct term for it but I'm thinking of a voltage divider with a cap across the top resistor- much the same as a volume with a bright cap. The two channels on a four input marshall are blended with 470k or 270k resistors. The lead channel generally has a 250pf or 500pf cap across it- you could try something like that with your bright cap. A circuit like that is easier to design if there is a fixed resistor as the path to ground. A great example would be the blackface fender verb blend circuit. It creates a hi frequency shelf that lends a lot of that fender sparkle...and makes them sound harsh with fuzz pedals.

jamie

[dehughes]

Okay, that makes sense. I actually had a 500pf in there at first, as I was transitioning over from another tone wiring. I liked the 500pf better, IIRC, but took it all apart to try the Moonlight tone wiring.

I'll give the Big Muff tone knob a try next and see how that goes. Actually, I'll try Yunger's variation on it first and see what I think of that. Then I'll give Txstrat's idea a shot.

After that, I'll start making my own tone stack.

[imaradiostar]

The Big Muff tone circuit (unless scaled) really works best with low impedance drive and a buffer after it. Have any mosfets laying around?

jamie

[dehughes]

The Big Muff tone circuit (unless scaled) really works best with low impedance drive and a buffer after it. Have any mosfets laying around?

jamie

I do have a few MOSFETs lying about.....

I suppose I don't understand what in a circuit creates "low impedance drive", and I'm not sure what a "buffer" is, technically. I still have a lot to learn with circuits...

[yunger]

this reminds me of when i was endlessly searching for the perfect one knob tone control. i think i went through all the same stacks, in almost the same order as you.
you don't need MOSFETS or buffers if you try my circuit. it's filters are configured around the pot like a big muff but that's where the similarities end. i tried the big muff and thought it was a little too cartoonish and not quite useful in an amp. if you like it, i'll show you how to tune it to your preference. good luck.

[dehughes]

this reminds me of when i was endlessly searching for the perfect one knob tone control. i think i went through all the same stacks, in almost the same order as you.
you don't need MOSFETS or buffers if you try my circuit. it's filters are configured around the pot like a big muff but that's where the similarities end. i tried the big muff and thought it was a little too cartoonish and not quite useful in an amp. if you like it, i'll show you how to tune it to your preference. good luck.

You know, I juuuust finished putting your version into my amp. It's close, but still not quite there. I'm running a 500k tone into a 1M volume, at present. I find that there still isn't enough top end clarity, though I like the way the knob shifts things around.

I'm considering putting in a 1M tone and shrinking the .001uf cap to a 500pf, as well as raising the 100k resistors to 150k. What would you recommend, being as this is essentially going into a 6G3 circuit?

[HBamps]

this reminds me of when i was endlessly searching for the perfect one knob tone control. i think i went through all the same stacks, in almost the same order as you.
you don't need MOSFETS or buffers if you try my circuit. it's filters are configured around the pot like a big muff but that's where the similarities end. i tried the big muff and thought it was a little too cartoonish and not quite useful in an amp. if you like it, i'll show you how to tune it to your preference. good luck.

What's your circuit? Do you mind sharing?

[dehughes]

What's your circuit? Do you mind sharing?

A sample was posted higher up on this thread...

[dehughes]

this reminds me of when i was endlessly searching for the perfect one knob tone control. i think i went through all the same stacks, in almost the same order as you.
you don't need MOSFETS or buffers if you try my circuit. it's filters are configured around the pot like a big muff but that's where the similarities end. i tried the big muff and thought it was a little too cartoonish and not quite useful in an amp. if you like it, i'll show you how to tune it to your preference. good luck.

So, I just finished tinkering with things....

I have a 1M pot in there (maybe a bad idea?) and have tried raising the cap to ground, reducing the value of the .001uf cap to 500pf, as well as reducing the value of the 100k resistors to 56k each. I'm getting closer but also farther from my ideal..... I like the way the channel feels with 56k resistors and the 500pf cap on top, but there's just waaaay too much low end when I turn back the tone knob.

I suppose what I really need to do is understand what each of the components do in your schematic, yunger. I think I get it, but I still feel like I'm stabbing in the dark...

[yunger]

-if you're using a .02 coupling cap on V1's plate(as shown on the 6g3 schematic) your likely getting too much low end with this tone control. c2 on my schematic is .01. is that what you have?
-the larger the value of tone knob seems to drop high end. can you try a 250kb?
-dropping the .001 to a 500pF will scoop the mids a little more. as is the mid scoop is about 6db.
-maybe try changing c4 to .01.

[yunger]

I suppose what I really need to do is understand what each of the components do in your schematic, yunger. I think I get it, but I still feel like I'm stabbing in the dark...

pretty simple:
-R5 and C4 make a low pass filter
-R7 and the series capacitance of C2 and C3 make a high pass filter
-R6 keeps highs from dropping into oblivion when fully CCW on the knob.

[dehughes]

-if you're using a .02 coupling cap on V1's plate(as shown on the 6g3 schematic) your likely getting too much low end with this tone control. c2 on my schematic is .01. is that what you have?
-the larger the value of tone knob seems to drop high end. can you try a 250kb?
-dropping the .001 to a 500pF will scoop the mids a little more. as is the mid scoop is about 6db.
-maybe try changing c4 to .01.

Yes...a .02uf off the plate of V1 as per the 6G3 schematic. Could I compensate by adjusting values in the tone setup?

I'll try a 250k pot instead of the 1M.

Okay...the 500pf seemed a bit more scooped, in a way....

I had a .01uf in there, but that was with some alternate values, so I can't say exactly what it did. It seemed to add low end, or raise the low mids overall.

I think I'm (slowly) getting what's going on. I'll see if I can run that SPICE program on my Mac....I think I have a way to do that, but I've never tried.

[dehughes]

pretty simple:
-R5 and C4 make a low pass filter
-R7 and the series capacitance of C2 and C3 make a high pass filter
-R6 keeps highs from dropping into oblivion when fully CCW on the knob.

WAIT! So, essentially, that's a TMB EQ network without the bass pot (the 100k resistor R6) and without the midrange pot, yes?

If you removed R7 and instead put a 6k8 resistor underneath C4, wouldn't you have a Fender-ish tone stack, of sorts?