The MOD Squad

Note that I shorten pin 3, then mount pin 3 to the board via the 0.015uF cap. All of my shileded cables are grounded to pin 4. Next time I'll leave pin 4 un-trimmed to make this easier on the underside of the board.
1755660601614.png
 
That looks like a nice and easy mod, I thought you would like the switching with the DPDT on-on-on switch since it just makes more sense. (Thanks Passinwind for that idea)
Did you work out the capacitance with C2 in series with the voicing caps ? I think that C2 will affect the value of the wet HPF caps just a tiny bit but the higher C2 is the less effect it will have.
I wonder if you can easily bend leg 3 of the BTDR2 module straight out instead of cutting it short, I will have to wait a while before I make another one since I bought one of every other board Nathan has for my round 2 builds. He was out of stock of the Bathtub PCB's when I bought the others.
 
Tassieviking said:
Did you work out the capacitance with C2 in series with the voicing caps ? I think that C2 will affect the value of the wet HPF caps just a tiny bit but the higher C2 is the less effect it will have.
Click to expand...
Good question, I’ll check my notes. My current build has a 1uF in place.
 
So, in terms of simply bending the pin, that would work well. However, I needed to cut Pin 3 because I had already installed the module for my previous design.
I checked how the capacitance of C2 would impact the Fc values. Because the Fc of C2 is so low compared the the voicing switch Fc's. It makes very little difference.
I did notice that I didn't change the Fc when I shift C2 down to 0.47uF. At this value, the Fc is between 50 - 40Hz at -3dB/octave depending on where the mix pot is set.
I think I'd go back to a C2 at 1uF which gives me a Fc ~20Hz.
0.68uF would get an Fc ~30Hz.
 
Tassieviking said:
This might be one mod on the BassDude that not many have thought of, change a few values on some components and add a second Bright cap on top of R12 and you have a Marshall JTM45 preamp, of course the JTM45 has 2 channels, one with and one without Bright caps so place both caps on a switch if you do this mod.

What do we need to do?
We could place a 68k resistor between the input jack and the PCB but I would not do that, the only real difference is that V2A does not have a cathode capacitor C9 and we need to add the 500pF Bright capacitor on top of R12.
R16-1k6, R17-820R, C8-100uF (120uF), C9-Leave Out, R12-Add a 500pF capacitor over the top, Tone Stack-please yourself with this one.

The more serious modder would also change the tone stack to a classic Marshall tone stack, we would just mount the pots in the box and then wire the resistor and the 3 capacitors to the pots themself and then run 3 wires to the PCB at the right places. ( C7 / C10 junction and R15 / Master junction and also a ground wire )

If you build a JTM45 BassDude then it might make sense to try some 12AY7 tubes in the real BassDude so they sound different, you might just need one 12AY7 and one 12AX7 in the BassDude but you just have to experiment with different tubes.
Click to expand...
Ooooooooo, I like the idea of turning the Bassdude into a JTM45!
 
I haven't tried it yet myself but when I do it will be on a new PCB, I just wanted to point out the possibilities that exists with the PCB.
If you do build one please post some pics of your build and let us know what you think.
Cheers
Mick
 
You must log in or register to reply here.
Back
Top