AN Wonderland Contour Circuit

[W5FH]

Hello-
I am in process now of building a copy of the John Mayer Custom Reverb/ AN "Wonderland" amplifier based on info gleaned on this site. Attached is the schematic. My question revolves around the "contour" control, namely C-29 (4n7) and R-51 (250KA pot) of which are across the output of phase inverter. I have not incorporated this circuit into a build yet and was curious about its operation and how important it is to the character of this amplifier. The front panel is fairly crowded and I will have room for either the "contour" control or a "presence" control but not both. I like the Hiwatt phase inverter and its presence circuit and was thinking of incorporating it into this build. I have tried to research this circuit both cannot find anything about it so if anyone here has a few moments to educate me on what the "contour" control is doing I would appreciate it. As I understand the pot and 4n7 capacitor is a controlling the frequencies that apparently are being cancelled, as the phase inverter triodes are 180 degrees out of phase? Is this control important to the operation of the amp? Have watched some videos and observed some use of the control.
Also I am going to use a 6K6 reverb driver with an Edcor 7K to 8 ohm driver transformer, in a circuit similar to old Fender 6G15 Reverb unit. Keeping 6K6 plate voltage around 250 vdc or so to not drive pan too hard.
Thanks

[sluckey]

My question revolves around the "contour" control, namely C-29 (4n7) and R-51 (250KA pot) of which are across the output of phase inverter.

It's exactly the same as the Vox top cut. Look here...

https://sluckeyamps.com/VAC15/Vox_AC15.pdf

[Roe]

the vox top cut is simpler than the SSS high filter but very effective for removing top end. I prefer a no-load pot myself since the stock vox circuit reduces gain and brightness slightly even when you turn down the cut control

[W5FH]

Thanks for replies-
I found lots of info under "Vox Top Cut" searches, thanks for tip there. I wanted to ask Roe what he means by a "no load pot"?
Thank you.

[timrobertson100]

I find the contour in my wonderland very useful and would recommend keeping it.

[sluckey]

I wanted to ask Roe what he means by a "no load pot"?

A no load pot becomes an open circuit when turned all the way in one direction. This has the same effect as connecting a switch in series with the pot. It totally removes the top cut circuit.

https://www.tubesandmore.com/products/p ... ft-no-load

[W5FH]

Thanks all for helpful replies.