Baxandall (James) Tonestack with LPB1

[mojo321]

This is the final corrected and verified version. The Log"B" pots are used in the tonestack calculator. If you used regular log pots, go to the tonestack calculator and see how that changes the tone ranges. You might want to make some adjustments to the left side values. Socket the left side values to make changes to the tonestack. Enjoy!

[mojo321]

[cylens]

thanks a lot for this!

2 questions:

-> any idea where I could source these logb taper pots?
-> do you think i could run line-level signals through this?

[mojo321]

No idea.  I know that if you use regular log pots you will still have the same ranges available, because the limits are set by the value, not the taper.  So it isn't a huge loss to have to use regular log pots.  They just have a lot of the action bunched up on one very sensitive end.

HOWEVER, it would be really cool if someone could go into the pot custom taper calculator and mess with some resistors on larger valued log pots to "turn them into" these value and tapers that the Baxandall really craves!  

As far as line level goes, I don't know.  I'm sure it works, but I do know that the LPB1 was very much needed, as the tone circuit really pulls the level down. (which is probably why your guitar only has 1 cap soldered to the tone knob instead of a BMP circuit.  More stuff in the circuit=lower level output signal)

[Silver Blues]

Forgive my ignorance but... Log B taper? "B" is the standard code for a linear taper pot. "A" is the code for a logarithmic taper pot. "C" is anti-log, and so on and so forth. I'm not sure what "Log B taper" is.

[Beaker]

I wondered this as well - logB?

I've not built this up yet, but have built a couple of the ROG Ginger pedals that use the Baxandall tone circuit. That uses 100k log (A) taper pots for treble and bass (as well as volume and gain), and they work fine.

http://www.runoffgroove.com/ginger.html

[mojo321]

Yeah, I know.  "B" means linear.  

But this is a weird Log pot specifically created for the Baxandall circuit.  Why would they do this?  My theory is, the circuit is so simple and beautiful, they felt it justified the custom tapers.  But you are definitely better off with LogA tapers than using a LinB taper.  

I should make that clear:  Just because it says "LogB", don't run off and put "B" pots in there, because those would be Linear.  You wouldn't be happy with how bunched up the action on the knobs will be.  

[Beaker]

Ah, that explains it, and I've learned something I did not know before. Thanks Mojo!

[mojo321]

Rock and roll Beaker!

[Silver Blues]

Yeah, didn't know that either. All the Baxandalls I've seen are log (A) taper. Interesting

[tabbycat]

thank you mojo321, am building a test-box of tone stacks to decide which to build in with each pedal (am a fussy bitch) and this goes straight in.