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Hi,

I'm building some mammoths, with improved tonestacks.
Here's the schematic I'll be using. Kudo's to the creator of the James stack. I don't know who it is, but I think I first saw it in the James Muff and the SFT. It must go way back though..
The output buffer is also from the James muff.

Merry christmas!

Great idea, I had just been planning a Woolly Mammoth with a BMP tone control.

I'm guessing that R5,6 is a pot and R9 and R10 is another pot.

~arph wrote:Here's the schematic I'll be using. Kudo's to the creator of the James stack. I don't know who it is, it must go way back though..

The James is the passive version of the Baxandall tone control - I believe it's so named because Peter J. Baxandall's middle name was James. So this would be from the 1950s.

Here's the original paper:

http://home.comcast.net/~stphkeri/Negat ... ckTone.pdf

Yes R5,6 and R9,10 are pots

also note that the "Wool" control is missing from the schematic. There should be a 2kB pot between the negative side of C3 and GND
Plus to tame the noise I got when built, I placed a 220pF between the base and collector of Q1

oldgravity wrote: The James is the passive version of the Baxandall tone control - I believe it's so named because Peter J. Baxandall's middle name was James. So this would be from the 1950s.

Here's the original paper:

http://home.comcast.net/~stphkeri/Negat ... ckTone.pdf

Nope, I was wrong. The James is by E.J. James, and here's his original article:

http://home.comcast.net/~stphkeri/James ... ontrol.pdf

So the James tone stack actually dates to the 1940s!

Ha,

And that document has a correspondence in it that says it was designed by Michael Volkoff in July 1939

So perhaps it should be the Volkoff tonestack then..

What should the pot values be for R5,6 and R9,10? Looks like you have two 1M resistors for R5,6 and two 500K resistors for R9,10.

Well, it's the james tonestack from the 21st century big muff.

Bass 1M lin, and treble 500k Lin or 1M lin. Both work fine.

It looks a bit funny since the schem is from LTSpice. I was simulating the circuit and decided to throw it out here as I had it drawn up already. That is also why the wool pot is missing. I have it at max gain here.

I was simulating the tone control settings, that is why you see no pots there but two resistors with a parameterized value.

One resistor has value {1meg * param}, the other {1meg - 1meg * param} If we step the param between .1 and .9 then the first resistor will go from 100k up to 900k and the latter from 900k to 100k, hence simulating a rotating pot. The point these two resistors connect is the wiper.

When I built it, it was too noisy with the wool maxed out, so I added the 220pF

I have this in the breadboard right now! I put it together a couple days ago. I hadn’t seen this post until just now!