Solenoid (Soul Driven) Overdrive bass switching resistors

[Iceman53]

I'm considering building the Solenoid Overdrive. So I looked up The bass boost options on Xotic's site. Xotic shows FOUR switch options, using the 2 internal dip-switches. Looking at the Solenoid schematic in the PedalPCB's Build Docs, if both R9 and R10 resistors are identical, that results in THREE bass options, not FOUR. 1 ON & 2 OFF is the same as 1 OFF and 2 ON. I found a different schematic (Aion) that shows a 15k and a 10k, instead of two 15k resistors. Looking for someone to confirm that 15k & 10k are the correct as opposed to the TWO 15k resistors, which I suspect is a mistake.

thanks in advance!

 

[Iceman53]

Update: I substituted a 25k pot for the 2 resistors and the dip switches. I mounted the pot to the enclosure and wired it in from the rear of the board. That gives me external adjustment for the bass options instead of opening the back. After completing the pedal, I didn't like the way the Gain taper worked. It was almost fully on at 9:00 on the pot. I replaced the 1 Meg pot with an A500k pot. That cured the 'early' Gain saturation and spread out the range of the pot much better. Posting just in case someone builds this and runs into the same issues.

 

[xefned]

Thanks for sharing this mod.

Am I understanding correctly that *adding resistance* = *adding bass?*

The Xotic website seems to imply the reverse, that each ON position connects the dip switch and adds the resistors to the circuit.

But OFF + OFF is actually the "flat" position, right? And your bass pot, fully clockwise is adding 25k resistance? Or is it wired in reverse so that 0Ω = full bass? Thanks for any advice.

 

[Iceman53]

I just verified that turning the pot clockwise increases the bass. I opened the pedal up and verified that turning the pot clockwise ADDS resistance to the circuit. So, 'ON + ON' (on the chart) does agree with the way the pot is acting. ON + ON is no resistance (a short) in that part of the circuit, results in 'Flat' or minimal bass. And, 'OFF + OFF' is maximum pot resistance and the most bass boost. If the pot would be wired using the opposite lugs, the chart would still be correct, except the maximum bass would be full CCW, and minimum bass would be full CW. Hope this helps. Also...there is NOT much difference in bass boost/cut between the full CW and full CCW settings. At least not on the one I built. Increasing the value of the pot might result in more bass. That's just an educated guess.

 

[xefned]

Hey, thanks Iceman! Very nice of you to open it up and check. That was super helpful. I hope I can repay the favor sometime.

I'll play around with the pot value and see if it changes the bass amount. Although I suspect it's not an important part of the sound of the pedal since they put it on dip switches inside, rarely to be adjusted. I might just try it with a DPDT switch on the front and pick just two of the 3 boost options, along with a flat option.

I don't imagine a whole lot is going on at 125Hz anyway.

Thanks again man! I'll report back with what I figure out. Appreciate it!

 

[xefned]

OK, I could be smoking crack, but I hear the most bass when both resistors are taken out of the circuit.

So that diagram above from Xotic's website, where both dip switches are "OFF" seems to be accurate. (I'm not doubting your findings though Iceman! Wiring to lugs 2 and 3 of the pot would recreate your findings, i.e. less resistance as you go clockwise.) So I suspect increasing the value of the pot to 50k would continue to give less bass.

Anyway, none of this really matters. I'm just chiming in for future travelers. I wired the resistors to a DPDT on-on-on switch. When it worked in reverse of how I expected, I just flipped the toggle switch around. All good here.

Most importantly: I'm LOVING this pedal. It kicks the Timmy to the curb (for me) and rivals the Zen drive. I'll have to do it side-by-side with the Zen Drive. I'm getting more chime than ever with the treble cranked. I love it!

And what you said: the bass boost hardly makes any difference, especially if you're using single coils. I had to plug in a bass guitar to even confirm for sure what I was hearing.

Rock on!

 

[xefned]

I had to move the bass boost switch after drilling because it got in the way of the PCB.

I covered the original hole with a sticker and drilled a new one. It looks janky, but I don't care much.

Future builders: unless you're into doom metal, just skip the bass boost altogether. After playing with it for most of the afternoon yesterday, I'm convinced it doesn't add anything good to the sound. Everything good happens with the Tone (Treble) and Mids knobs.

 

[Feral Feline]

Did you try it with a bass?

 

[xefned]

Did you try it with a bass?

Yes. In fact, (mentioned earlier) I had to plug in a bass just to be sure the switch was working.

The bump is subtle and below the low-E string of a 6-string guitar. Other player's mileage will surely vary here because I'm more a chimey, single-coil guy than a doom drone guy. For a lot of us, the bass knob on our guitar amp will be more useful than the bass boost dip switch on this thing.

 

[Feral Feline]

... I had to plug in a bass guitar to even confirm for sure what I was hearing.

Rock on!

Embarrassed I missed that.

Just so used to guitar-centricness on effects websites. PPCB's forum, IMO, has the most bass-friendly atmosphere of all the DIY boards (Madbean is a close second).

 

[Chuck D. Bones]

Interesting that Xotic copied the Boss Blues Driver's output stage, including the bass boost gyrator, for the Soul Driven. That gyrator produces a narrow bump in the bass response around 120Hz. The Soul Driven's DIP switches determine the amount of bass boost. If you really want to kick up the bass, then the gyrator can be retuned to produce a broader bump that's centered around 50 to 60Hz.

 

[xefned]

Future builders: unless you're into doom metal, just skip the bass boost altogether. After playing with it for most of the afternoon yesterday, I'm convinced it doesn't add anything good to the sound. Everything good happens with the Tone (Treble) and Mids knobs.

I have to recant this statement.
The bass boost actually brings out some heft in my neck pickup that I didn't notice before.

It's especially noticeable when comparing to similar drive circuits like the Zen drive.