Adding A DEFX Mod To Vero... Head Scratcher

[Ginsly]

Since the Zuperbee (modded SSBS Buzzz) is unavailable at the moment (postal strike??), I was going to add this Vero layout to my queue before I jump into a few PPCB boards. Problem is, it leaves off the DEFX mods - at very least I'd love to incorporate the switch that adds the 6th transistor to the Starve control. This layout also omits the Octave Trimmer . You can see the Starve circuit in the bottom left of the DEFX schematic, and the switch itself right by Q6 (sorry, small text!). I feel like this may be easy, but I can't quite figure out how to do it... Here's the Zuperbee link if the schematic image below is just too crappy: https://drive.google.com/file/d/1BlrXF5_pRtyCHNk_Ebg3PBa0xg8n45cd/view

 

[Ginsly]

Maybe this is a tricky one? Or maybe I've finally worn out my welcome here...

Here's a close-up of the Starve part of the circuit and the switch itself:

 

[Feral Feline]

 

[Ginsly]

Hahaha... Got your message, replying now! You rock!!

 

[Feral Feline]

For anybody landing on this thread...

Ginsly and I have worked out a switch, SPDT on-on, to have the Q6 final stage toggleable between the starved voltage and reg full +9v:

Okay so the 33k that goes to the Q6 collector and the 680k that goes to Q6 base both have to be lifted at their common ends, ie the vero row that has them connected to the "starve 3", tie those now loose ends together and run a wire from the same loose ends to a SPDT on-on's LUG 2;

On whichever outer lug you prefer attach a wire between the chosen outer-lug and the column/rail you just disconnected the resistors from ie the row labelled "STARVE 3".
The other remaining lug on the switch gets a wire between it and the STARVE POT's MIDDLE LUG.

However... the octave-trimmer...
Looking at the two 22k resistors from the bases of Q4 & Q5 to ground, well, there's simply no room on the vero to place a trimmer that interrupts those 22k Rs to ground.


I've already mentioned to Ginsly that I think the way to go is to match the transistors as closely as possible (and for that matter I'd try to match the two 22k base-resistors and even match the two 100k V1-power resistors) in hopes to not need the trimmer, which is really mainly needed/used IF the transistors are NOT closely matched — in which case the trimmer can tune-in the octave effect.

To add the trimmer I'm thinking another row on the top of the vero could be added, but even so it's a bitch to shuffle components around to make room for the 22k resistors to be connected to the trimmer and subsequently trimmer to ground. The other option is a small scrap daughterboard or just make the trimmer free-floating (with all the resultant problems doing that could entail) ...

Has anybody got an easy way to add that trimmer?
Hmmm... I think I have, now. I was fixated on the trimmers that resemble a little hockey-puck on the board. Instead, I give you...

THIS type of trimmer. Lift the 22k ends that go to ground, solder them to the outer (bent 90º) legs of the trimmer and the centre-leg soldered to the ground-rail.


BOOM!
Done and dusted.

 

[Ginsly]

For anybody landing on this thread...

Ginsly and I have worked out a switch, SPDT on-on, to have the Q6 final stage toggleable between the starved voltage and reg full +9v:


However... the octave-trimmer...
Looking at the two 22k resistors from the bases of Q4 & Q5 to ground, well, there's simply no room on the vero to place a trimmer that interrupts those 22k Rs to ground.


I've already mentioned to Ginsly that I think the way to go is to match the transistors as closely as possible (and for that matter I'd try to match the two 22k base-resistors and even match the two 100k V1-power resistors) in hopes to not need the trimmer, which is really mainly needed/used IF the transistors are NOT closely matched — in which case the trimmer can tune-in the octave effect.

To add the trimmer I'm thinking another row on the top of the vero could be added, but even so it's a bitch to shuffle components around to make room for the 22k resistors to be connected to the trimmer and subsequently trimmer to ground. The other option is a small scrap daughterboard or just make the trimmer free-floating (with all the resultant problems doing that could entail) ...

Has anybody got an easy way to add that trimmer?
Hmmm... I think I have, now. I was fixated on the trimmers that resemble a little hockey-puck on the board. Instead, I give you...

THIS type of trimmer. Lift the 22k ends that go to ground, solder them to the outer (bent 90º) legs of the trimmer and the centre-leg soldered to the ground-rail.


BOOM!
Done and dusted.

@Feral Feline to the rescue, yet again! Can't express my gratitude enough, this is incredibly helpful.

This skinny trimmer looks plenty "crammable" onto the Vero, but I could always just make it an external pot too - it can be kinda fun to intentionally unbalanced Q4 and Q5. I had a Wattson FY-6 that I used on bass, and changing that trimmer helped dial DOWN the octave which was helpful sometimes.

VERY psyched to include the Q6 Starve switch, too. I'll order a Zuperbee when he's up and running again, but it'll be fun to mess with Vero in the meantime! Made my day, FF!