Simble / Symbolic OD MKII mods?

Preverb

Preverb

Active member
Hi everyone. I used to have an original Simble pedal but there is a new variant which apparently has more clarity and less flubbiness.
Has anyone had a look at the new variant to figure out if its easy to mod the current pedalPCB project to similar values to the new MKII version?
 
Preverb said:
Hi everyone. I used to have an original Simble pedal but there is a new variant which apparently has more clarity and less flubbiness.
Has anyone had a look at the new variant to figure out if its easy to mod the current pedalPCB project to similar values to the new MKII version?
Click to expand...
Can you post some pics of the PCB?
 
Also, which Simble? There some confusion with the Simble name. It was offered by Mad Professor (I think) but was not designed by Bjorn Juhls.
It's a nice sounding Zen Drive variant. But the name "Simble" was re-purposed by Bjorn with his own company and I think that was more of a boost than an overdrive. (I could be wrong on all accounts, I often am:)
 
Ok this is creepy, I was doing a quick Google search for the Simble and my own post and demo came up....... :LOL:

MichaelW

DEMO Thread 'Symbolic Overdrive (Mad Professor Simble Overdrive)'

Continuing on my quest to build all the Bjorn Juhls circuits I can find, I found out after I ordered the board that the Mad Professor Simble Overdrive was not a Juhl's design but rather was designed by another Finnish designer named Lassi Ukkonen for Mad Professor. Apparently there was some trademark issues as Juhl's is known as the "Mad Professor" and they were marketing a design that he had nothing to do with. It was discontinued by MP and the name "Simble" has been re-purposed for a boost pedal (presumably designed by Bjorn).

Anyway, looking at the schematic of this pedal it's evident...
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There was the Simble, the Simble Predriver (which I think is the boost, maybe?) then the Twimble that appears to be a Simble + Predriver in one.

Now there is the Simble MKII. It looks like a new revision of the original overdrive... maybe.
 
Robert said:
There was the Simble, the Simble Predriver (which I think is the boost, maybe?) then the Twimble that appears to be a Simble + Predriver in one.

Now there is the Simble MKII. It looks like a new revision of the original overdrive... maybe.
Click to expand...
Yah it's confusing as hell.
 
Robert said:
There was the Simble, the Simble Predriver (which I think is the boost, maybe?) then the Twimble that appears to be a Simble + Predriver in one.

Now there is the Simble MKII. It looks like a new revision of the original overdrive... maybe.
Click to expand...

MKII sounds like they tweaked the original. The description was that it is a bit less boomy / muddy and the tone controls had more range. That was my main issue with the original but it had a smooth character that I really liked otherwise. I actually have an unfinished symbolic that is in storage so it would be great if I could just modify some components to get close.


MichaelW said:
Can you post some pics of the PCB?
Click to expand...

Unfortunately, I can't find any PCB pics online so far and I'm currently living in the middle of nowhere with no local guitar stores that would carry it. I had hoped maybe someone here had one or had also been looking into it.
 
Preverb said:
MKII sounds like they tweaked the original. The description was that it is a bit less boomy / muddy and the tone controls had more range. That was my main issue with the original but it had a smooth character that I really liked otherwise. I actually have an unfinished symbolic that is in storage so it would be great if I could just modify some components to get close.




Unfortunately, I can't find any PCB pics online so far and I'm currently living in the middle of nowhere with no local guitar stores that would carry it. I had hoped maybe someone here had one or had also been looking into it.
Click to expand...
Ahh I thought you already had a Simble and wanted to mod it. So you want to mod a pedal you don't even have yet? Welcome! You'll fit right in here...... :p
 
MichaelW said:
Ahh I thought you already had a Simble and wanted to mod it. So you want to mod a pedal you don't even have yet? Welcome! You'll fit right in here...... :p
Click to expand...
I used to own an original (MKI) and have the pedal pcb version partially built. The changes they described for MKII sound like they would be ideal to incorporate into the incomplete project.
 
Here's the schematic to the PPCB Symbolic.
Probably the first thing I'd look at to make it less "muddy" is reduce the amount compression that's inherent with the circuit.
This circuit is a bit strange in that it's like a backwards Zen with a set of hard clipper BEFORE the soft clipping.
I would socket all the diodes and try some different ones besides BAT41. Like maybe just some plain old 1N4148s.

I'd also think about leaving D4-D5 out completely.
You can also try reducing C8 to address the bass.

Without a schematic of the MK II it's going to be a matter of experimenting until you get to where you want it.

Hope this helps!

Schematic-Symbolic.jpg
 
I've been meaning to mod my Symbolic with the goal of cleaning up the low end. I was planning to mess with C12/C13, lowering the overall value there. Easiest first step is probably removal (or omission, if you haven't built yet) of C13. Let us know if you get to it before I do! :)
 
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