Son of Ben (Benson Preamp) Modifications Thread

Bricksnbeatles

Member known well
Inspired by @Big Monk’s recent modifications threads for the Electrovibe, XC Phase, and Hydra Delay, I thought it would make sense to create a dedicated thread to compile all of the popular modifications made to the Son of Ben circuit (Link to the PCB here).

Let's list them and see what we can add/subtract/clarify:

1.) omit c10 (c10 only existed in the first few Benson Preamps produced, and makes the pedal just a little bit more gainy) for current spec/less gain*
2.) reduce c10 value (gives light mid boost effect according to this comment from our resident guru, @Chuck D. Bones)*
3.) 18v charge pump (and increase capacitor voltage ratings accordingly) for more headroom**
4.) omit c5 (and c10) for noticeably lower gain


Not a ton of mods here so far, but it seems like a popular one to modify, so I’m sure we’ll be able to add more to this list together!


* these two could be combined by using a spdt or dpdt on-off-on switch (just depends on how neat you want your off board wiring to be) with a 10u and 4u7 (or other, smaller value) cap, giving you early spec(10u)/modern spec(none)/mids(4u7)

** using the spdt pads on the charge pump daughterboard, you could wire up an external on/on switch to allow both 9v and 18v operation
 
Inspired by @Big Monk’s recent modifications threads for the Electrovibe, XC Phase, and Hydra Delay, I thought it would make sense to create a dedicated thread to compile all of the popular modifications made to the Son of Ben circuit (Link to the PCB here).

Let's list them and see what we can add/subtract/clarify:

1.) omit c10 (c10 only existed in the first few Benson Preamps produced, and makes the pedal just a little bit more gainy) for current spec/less gain*
2.) reduce c10 value (gives light mid boost effect according to this comment from our resident guru, @Chuck D. Bones)*
3.) 18v charge pump (and increase capacitor voltage ratings accordingly) for more headroom**
4.) omit c5 (and c10) for noticeably lower gain


Not a ton of mods here so far, but it seems like a popular one to modify, so I’m sure we’ll be able to add more to this list together!


* these two could be combined by using a spdt or dpdt on-off-on switch (just depends on how neat you want your off board wiring to be) with a 10u and 4u7 (or other, smaller value) cap, giving you early spec(10u)/modern spec(none)/mids(4u7)

** using the spdt pads on the charge pump daughterboard, you could wire up an external on/on switch to allow both 9v and 18v operation

I was just checking this PCB out yesterday when i was looking at the Clandestine. I'll ave to throw it on my list!
 
For use with bass: I ended up switching out C6 and C8 for 330n (what I had on hand, though I think anything 100n and above would have been fine). That really opened up the pedal and makes it sound a lot fuller and more useful on bass. Also omitted C5 so that there's more gain before breakup.
 
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I’m also finding that running the pedal at higher than 9v (12/18) also opens things up for bass. BUT it doesn't break up as well. Has way more headroom before breaking up.
 
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1.) omit c10 (c10 only existed in the first few Benson Preamps produced, and makes the pedal just a little bit more gainy) for current spec/less gain*
2.) reduce c10 value (gives light mid boost effect according to this comment from our resident guru, @Chuck D. Bones)


* these two could be combined by using a spdt or dpdt on-off-on switch (just depends on how neat you want your off board wiring to be) with a 10u and 4u7 (or other, smaller value) cap, giving you early spec(10u)/modern spec(none)/mids(4u7)
So, if one wanted to achieve this, how exactly would it need to be wired up? I have extra switches and would love to have the selectable caps, but I’m fairly new to this and adding a switch to on-board components is slightly above my pay grade right now. Any help in wiring and how-to would be greatly appreciated!
 
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