Adding Midrange control to this tone circuit

[thehoj]

I'd like to add a little bit more versatility to this amp I'm using right now by adding a midrange control.

Here is the schematic:
http://www.lynx.bc.ca/~jc/yvm-1.jpg

I'm not familiar enough with how this tone stack accomplishes what it does.
Would I be removing R15, or R16 and replacing with a pot of some sort?.. Or what would be the best way to accomplish this.

Thanks.

[wizard333]

Replace R16 with a pot. There you go.

[thehoj]

Replace R16 with a pot. There you go.

Alright, I'll give that a try. Have any idea what this tone circuit is called? Or where it comes from?

I've been trying to identify another amplifier that uses something like it.. It seems somewhat close to this two-knob brownface circuit Adam's Amplifiers: Tone Stacks.. But they're still different.

[eschertron]

Alright, I'll give that a try. Have any idea what this tone circuit is called? Or where it comes from?

I've been trying to identify another amplifier that uses something like it.. It seems somewhat close to this two-knob brownface circuit Adam's Amplifiers: Tone Stacks.. But they're still different.

Looks like the Blonde Twin diagram. Mmmmm... blonde twins.... D'oh!

[pdf64]

Using the TSC classification TSC would probably be a james type.
Common in Ampegs http://www.webphix.com/schematic%20h..._portaflex.pdf
Pete

[thehoj]

Replace R16 with a pot. There you go.

I put a 100K pot in place of that 47K resistor.. Works great, gives me a nice range of mid control. Honestly a really great tone circuit I think.

[soundguruman]

I'd like to add a little bit more versatility to this amp I'm using right now by adding a midrange control.

Here is the schematic:
http://www.lynx.bc.ca/~jc/yvm-1.jpg

I'm not familiar enough with how this tone stack accomplishes what it does.
Would I be removing R15, or R16 and replacing with a pot of some sort?.. Or what would be the best way to accomplish this.

Thanks.

Download
behold the tone stack calculator

[thehoj]

Download
behold the tone stack calculator

Oh.. I've used that before, I thought it was used for playing with values in a handful of established tone stack's..
I just installed it again, I'm not seeing how to input a custom tone stack.

[pdf64]

It's the James type, as in Fender Vox Marshall James as you go along the tabs.
Pete

[eschertron]

Oh.. I've used that before, I thought it was used for playing with values in a handful of established tone stack's..
I just installed it again, I'm not seeing how to input a custom tone stack.

I've used the TSC quite a bit with 'imaginary' pots by taking a snapshot with the resistor at one value, then changing the value, snapping, and so on.
Also, If what you want is similar to an existing model but only a little less complex, it's possible to remove components by giving them ridiculously large or small values (depending on where in the circuit they are). If I learned SPICE I could do it without the grunt work, I suppose...

[Shane]

Another option is to replace the 33k resistor R17 with a pot wired as a variable resistor say 250k to 470k. Not exactly a midrange control but gives some very interesting tone changes. Try plugging that int the TSC and see what I mean.
Cheers
Shane

[isaac]

The interesting thing here is that, this tonestack will change your mids if you use it right. SO... If you put your treble and bass on ten you will get a mid scoop, which becomes smaller as you decrease the controls. So when the controls here (T and B) are both at 12 oclock, you get a flat response, (yours has slightly less common cap values so it wont be perfect, but close anyway) and when you reduce the Treble and bass to 0 you get a mid hump. Try it in the TSC, so technically you don't need a mid pot, but if you find you still like the mid pot you have, then great, otherwise I'd use it like it is.

[wizard333]

That is true of any tone stack; all things are relative. It does change the level you send to the next stage, loading of the next stage, etc. etc. though if you adjust mids by turning treble/bass down, which is why most people prefer to have a midrange control.

[isaac]

That is true wizard, this circuit isn't quite normal but again, that's true. I guess you can get extra scooped or extra big mids with setting all controls around to the extremes.