Adding a bias pot to the Tone Vendor

[jcrews]

Solid. I'm gonna order some trimmers today. I'll go back and see which resistor they need to replace specifically. since im running both pots in series, I'm assuming thats just both outer lugs and both wipers to the same hole? Will I need to run the outer lug of my external pot to ground ?

I have some 100k linears for the external Bias knob. Should i wait to get readings before I order the trimmer (value?) or is there a ballpark you can reco?

 

[jcrews]

@Big Monk
Looks like it's a 5k in both spots in the face version of this bias scheme. But i see a 100k in yours?
Just want to make sure i order the right pot and timmer combo.
I have a decent selection of pots on hand, but I'm not as well stocked on these trimmers.

 

[Big Monk]

@Big Monk
Looks like it's a 5k in both spots in the face version of this bias scheme. But i see a 100k in yours?
Just want to make sure i order the right pot and timmer combo.
I have a decent selection of pots on hand, but I'm not as well stocked on these trimmers.

Keep in mind, the Fuzz Face adjust it's Q2 (the Tonebender's Q3) by adjusting Q2c directly. In the Tonebender, adjusting Q3c is best done by adjusting Q2c.

Keep the following relations in mind:

Fuzz Face Q1 = Tonebender Q2
Fuzz Face Q2 = Tonebender Q3

 

[jcrews]

I see it now..... What value are you using for Q2c trimmer? I now have wrapped my head around using a 100k dual gang to "fine tune" the trimmed bias on Q1 and Q2 together but I really don't think i have room for a dual gang (double boxing this one with a sunface). I had intended to only use the trimmer/100k external setup for Q2 alone. If you think this won't allow for enough adjustment I can maybe look for some 9mm dual gangs or think about drilling out a new case. I have two of the boards ready to go so I will def kick around the dual where i have room on my next build. If you think It's not worth it to just leverage Q3 by messing with Q2 alone, then maybe I just do an internal trimmer?

If you could only add in single gang external would you do it?

Here's where im at with it.
Sunface side is done and dialed in perfectly. (ignore the lug pots on the tonevender side. They were just placeholders so i could chose knobs that worked)

 

[Big Monk]

I see it now..... What value are you using for Q2c trimmer? I now have wrapped my head around using a 100k dual gang to "fine tune" the trimmed bias on Q1 and Q2 together but I really don't think i have room for a dual gang (double boxing this one with a sunface). I had intended to only use the trimmer/100k external setup for Q2 alone. If you think this won't allow for enough adjustment I can maybe look for some 9mm dual gangs or think about drilling out a new case. I have two of the boards ready to go so I will def kick around the dual where i have room on my next build. If you think It's not worth it to just leverage Q3 by messing with Q2 alone, then maybe I just do an internal trimmer?

If you could only add in single gang external would you do it?

Here's where im at with it.
Sunface side is done and dialed in perfectly. (ignore the lug pots on the tonevender side. They were just placeholders so i could chose knobs that worked)

View attachment 11745View attachment 11746

A single control for Q2c will definitely work. You just have to determine the values to use for the limiting resistor and internal trimpot and determine how much external range you want.