What are old Marshall bass amp head treble/mid/low frequencies tuned to?

[lungimsam]

Like when you see Treble/bass/middle/presence. What frequesncies is each tuned to? 50 /500/ 2.5/ 5k? Just wondering.
If you want specifics, I'd say a bass head around 1971.

Only asking here because you guys seem to know a lot about basses, and I cannot find any info like this anywhere online or on Marshall amp forums.

 

[Rocky]

It's not quite as simple as that. Here's a way to look at it using the values from the Super Bass Schematic from July 1970

TSC in the web

 

[lungimsam]

Yes I figured it wasn’t simple. I’ve seen the insides. Got a cajillion caps in them.

Thanks. I see what you mean. This is helpful. Can see how the B/M/T knobs affect the wave form.

Interesting that you can’t get a flat EQ with this amp, if that even matters.

So looks like a more accurate way to say it would be:
The bass knob governs the part of the wave between 10-800k
The middle knob governs the 1k and everything immediately around it.
The treble knob governs everything from greater than 12k-100k

But that too is just a generalization since altering these knobs at different settings seems to push the wave form around a lot in neighboring areas.
Sorta like those old novelty rocking wave boxes you could buy in toy stores years ago.

 

[Rocky]

The TSC is very handy for comparing, say a bassman vs a marshall, or seeing what a capacitor or resistor swap will do.

 

[Rambozo96]

Remember with this passive tonestack you can only cut frequencies. Here is a pretty broken down overview of the TMB tonestack that Fender used which Jim Marshall took inspiration from with his amps. It maybe different in a Marshall because I think it’s got slightly different values and Marshall’s tonestack is driven by a cathode follower stage as opposed to plate driven like on a typical Fender. https://robrobinette.com/How_The_TMB_Tone_Stack_Works.htm