Tonestack Connection Query

[chumbox]

Hey All

I started laying this first gen Sunn Model T tonestack out on my breadboard to see how it sounded but then I realised I have no idea what lug 3 of the bass control is connected too?  At a guess it's connected to the bias circuit, but what if I don't have a bias circuit.  Little confused to be honest.



Thanks in advance!

[Brisance]

open maybe?

[Groovenut]

I'd say it's left open. The presence control is the same way. I believe both are wired as variable resistors.

[Groovenut]

BTW, this tone stack is no different than the standard Marshall, Fender tonestack. It's just drawn differently. The values are the same as the Marshall Bass Plexi

[chumbox]

Now that I'm looking at it and the fender stack I can certainly see the similarities. Not a surprise now that you mention it since the model T was based on the 59 bassman. So basically I should just find a fender tone stack that I can understand the schematic of and the outcome would be pretty similar with similar values.