Vox AC15C1 - adding Lar/Mar Type 2 Master Volume

[Big_Mike]

I recently purchased a used Vox AC15C1 for a good price, and looking at the schematic and layout, it appears Vox used a Type 3 Crossline master volume on this amp.  I find that at lower master volume settings, the sound really thins out.

I was thinking of maybe swapping out the Crossline MV for a Lar/Mar Type 2 MV.  I have found on other builds that the Lar/Mar does well on the lower end of the volume range.

The only difficulty I have is trying to figure out the physical connection for the Dual gang pot.  It looks like the pot would replace resistors 86 and 89, which are the 220K resistors on the board.  I guess my question is if you remove those two resistors, which solder pads should go to lugs 1, 2, and 3 on the pots? 

Below is a link where you can see the layout of the main PCB board:

https://reverb.com/item/62785670?utm_source=android-app&utm_medium=android-share&utm_campaign=listing&utm_content=62785670

Here is a link to the schematic:

https://www.tdpri.com/attachments/ac15c1-schematics-rev-2-pdf.291408/

[stratomaster]

The challenge is taking 2 pads and converting it to 3.

With the grid leaks in place, the output of the PI goes to the grid leak resistor, one side of the crossline master, and the input side of the gridstopper.  Use your meter set to continuity to find these 3 pads per side and mark them down.

With the LarMar the input to the pot is the output of the PI still, so that's an easy 1:1 swap. Same with the ground reference. The wiper, however, should now feed the gridstopper.  This is where you'll need to get creative.  If it were me, I'd cut the trace that originally tied the crossline master to the grid leak. Then I'd wire the wiper to the pad that used to have the crossline in it. If you're not too keen to cut traces, you can accomplish the same thing electrically by lifting the input end of the gridstopper.

EDIT: disregard the advice above as it looks like there's more to this circuit. There's a bias tremolo at play and the placement of the crossline precedes the gridstoppers.

In this case I'd depopulate the 10k resistors after the tone control and use a "Type 1" dual 1M pot instead of the Lar Mar.  This should leave the bias tremolo undisturbed and give you the performance you're looking for.  Ground the dual pot to the bottom of R85.  The wiper of the pot would go to the downstream side of the 10k resistor pad and the input to the pot to the upstream side.