Double checking my logic for increasing mid scoop in a tone stack.

[chumbox]

Hey All

Pulled the tone stack design from a Peavey 6505 as it has a great scooped mid, but when I put it at the end of a pedal the mid scoop was barely noticeable.  In order to increase the scoop my guess is to increase C42 to a higher value such as 100n?  Just wanted to make sure I'm heading in the right direction.  Happy with treble and bass at the moment, it's the mid scoop that just didn't hit the mark.



Thanks in advance

[GGBB]

Looks like a standard Fender-style tone stack. Search for and download the Duncan Tone Stack Calculator - great tool for this kind of thing.

[chumbox]

Oh yeah the Duncan TSC.  Thanks GGBB, totally slipped my mind to go download that! Yeah standard Fender-style stack for sure/.

[J0K3RX]

Replace R26 with a "Sweep" pot like a Krank...  Should be able to get a deep scoop with that.

[chumbox]

I like the look of this for the flexibility or to at least find a sweet spot J0K3RX.  Thanks heaps.

[PBE6]

It could be an impedance mismatch. Not sure how the rest of your circuit looks, but putting a buffer before and possibly after the tone stack should  improve its performance.

[J0K3RX]

PBE6 has a point.. And the 6505 has a pretty standard Marshall tone stack. Would be helpful to know what pedal you are putting it at the end of? As I said, this is a pretty standard Marshall stack and how it reacts in the 6505 amp ain't gonna be how it works at the end of a stomp box... 

[chumbox]

Sorry guys, should have said I was removing the tone at the end of the Wampler Plexi Drive and replacing it with a Marshall/Fender style stack (as that made more sense in my head). I know the Plexi Deluxe has a full EQ section but I didn't have a schematic, so took my own take on it.  I used the Peavey 6505 schematic only because the amp has a good scoop but turns out the tone stack on that amp is not that different to any other, the amp is obviously playing a big role in the mid range. 

Plexi Drive Schematic:

[chumbox]

Well the Krank sweep control certainly adds a whole lot tone adjustment. The mid control is still more like a fine tune but the sweep really changes the whole spectrum. Kind of lets you pull blues and crunchy doom metal from the same circuit. Worth playing with some more. Thanks all.

[J0K3RX]

You are removing R11, C8 and R12, C9 right? They are a couple low pass filters and you might as well remove everything after the last JFET and build your Marshall or whatever tone stack after that...

Maybe you can try this? It's the Marshall stack with the "Thrash" scoop before it that James Brown designed for Peavey before he moved on to the 5150 and JSX series amps. He came up with the "thrash" option found on a lot of Peavey amps and a few pedals. He is still using variants of this design today with his company Amptweaker. I like going over the old Peavey schematics because they are a goldmine for his "tweaks" and a lot of what you will find is close to what you will find today in the Tight Metal, Tight Rock, Tight Metal Pro etc...