Complex OD vs Dirty Sanchez or Thermionic

[Bucksears]

Putting the cart before the horse a bit here because my boards aren't even here yet (but should be within a day or so), but is the architecture THAT different for Complex OD?
Asking because it would be pretty incredible to modify the Thermionic Deluxe to be a Thermionic/Complex.

Thx!
- Buck

 

[Robert]

You can absolutely do it, in fact that's how I verified the circuit before ordering the first batch of PCBs. The Complex is closer to the Dirty Sanchez than the Thermionic because of the added mid control, so the Deluxe fits the structure perfectly.

I will say though, after a few minutes with the Complex you'll probably forget all about the Thermionic side....

 

[jubal81]

Speaking of the Complex, I started stuffing my board today and I'm wondering if the LEDs are just red diffused.

 

[Robert]

Yep.

 

[jubal81]

Yep.

Dude.
Just got the Complex rocking and I might be done building MIAB. I'm seriously impressed. Dirty Shirly sounded to me like a typical fizzy distortion but this thing is a whole different beast. The clipping is smooth and the EQing is next level - sounds very sophisticated with a very usable tone control set.

 

[Bucksears]

Dude.
Just got the Complex rocking and I might be done building MIAB. I'm seriously impressed. Dirty Shirly sounded to me like a typical fizzy distortion but this thing is a whole different beast. The clipping is smooth and the EQing is next level - sounds very sophisticated with a very usable tone control set.

Man, you’re making it worse!
I’m hoping this will be ‘the one’, as the production version has gotten (almost) unanimous rave reviews.

I have a Brown Betty and Thermionic Deluxe almost ready to box up; if the incoming Complex boards are all-that-and-a-bag-of-chips after I build them, I may have to do some tweaking on the previous two.

 

[Betty Wont]

Does the Complex have as much gain as the Thermionic? I was dissapointed to find the brown betty does not.

 

[Bucksears]

Does the Complex have as much gain as the Thermionic? I was dissapointed to find the brown betty does not.

No, from what I gather the Thermionic is higher than the Brown Betty/Dirty Sanchez and the Complex.
Not that that's a bad thing. It's sounding like the Complex/Smallbox OD is hitting a sweet(er) spot for the hot-rodded Marshall sound.

 

[Robert]

One resistor swap can bring the gain up to Thermionic levels, if that's what you wanted to do...

I'd try it "stock" before making any changes though.

 

[jubal81]

No, from what I gather the Thermionic is higher than the Brown Betty/Dirty Sanchez and the Complex.
Not that that's a bad thing. It's sounding like the Complex/Smallbox OD is hitting a sweet(er) spot for the hot-rodded Marshall sound.

That pretty much describes my experience.
I think of the Sanchez as a DS-1 with more EQ controls. The Complex is much more like a hot tube amp. If you want more out of it, it responds really well if you hit the front of it with a boost - especially a mid boost. I'd be inclined to pair it with a Tube Screamer, Klon or other mid-hump OD of choice.

 

[Bucksears]

Got my boards today, and spent some time tracing out the board compared to the Dirty Sanchez schematic.
I found (what I think are) the differences to convert a DS to the Complex - @PedalPCB mind if I post my findings, or is that a no-no?

 

[Robert]

Nope that's perfectly fine. I'll have the full schematic posted in a few days.

 

[Bucksears]

Thx!
Ok, going by the Channel B (Dirty Sanchez side) of the Thermionic Deluxe, found these differences:

• R25B (4K7) + TIGHTB (100KC) - replace with 22K (or just leave in place and dial that combo down to 22K?)
• C8B (120p) - replace with 220p
• TRIMB (100K) - replace with 27K (or leave trimpot and adjust to 27K?)
• R18B (2K2) - replace with 47K + 470p in series
• MIDB (100KC) - replace with 100KA
• TOGGLE - use SPST to toggle in/out 470K resistor in parallel across lugs 3/2 & 1 of the 1M gain pot; guessing adding the resistor is 'low gain' and toggling it out is 'high gain'?
• C20 (100uF) - in the power section - replace with 47uF (or leave as is?) - the rest of the power section looks the same

Might be more to it than that (and I could be mistaken), but that's what I've got.

 

[Chuck D. Bones]

Thanks for doing that! Seems like pretty minor tweaks.
I think you mean:
R18B (2K2) - replace with 47K + 470p in parallel.
Strange that the MID would be changed to A100K. C100K has a nice even feel.

 

[Bucksears]

Thanks for doing that! Seems like pretty minor tweaks.
I think you mean:
R18B (2K2) - replace with 47K + 470p in parallel.
Strange that the MID would be changed to A100K. C100K has a nice even feel.

Yeah, I thought that should be in parallel as well, but still appears to be in series. I’ll triple check it tomorrow night or this weekend.
I could map out a trace in Adobe Illustrator this weekend to be sure on everything, but I probably should just wait for the schematic.
I’ll leave the 100KC MID in place in my Thermionic Deluxe build.
Thx!

 

[Bucksears]

Thanks for doing that! Seems like pretty minor tweaks.
I think you mean:
R18B (2K2) - replace with 47K + 470p in parallel.
Strange that the MID would be changed to A100K. C100K has a nice even feel.

Confirmed, you are correct: it is a 47K + 470p combination in parallel replacing that 2.2K resistor.

I'll build out the PedalPCB Complex board and test drive that before tweaking the Thermion Deluxe.

 

[Barry]

Thanks for doing that! Seems like pretty minor tweaks.
I think you mean:
R18B (2K2) - replace with 47K + 470p in parallel.
Strange that the MID would be changed to A100K. C100K has a nice even feel.

Would the addition of the 470pf to the 47k really make an audible difference?

Or is it a 47K resistor with 470pf in parallel which makes sense now, duh

 

[mjh36]

I couldn't hear anything with the R18 47k/470p. So I used a socketed 4n7 and a 47n. I could hear a definite boost with those. Room to play there I'll keep experimenting.

Other than that all I changed was the C8 (220pf) and adjusted Trim and Tight to taste and let the rest be. So not quite a Complex but it rocks!

 

[ThinAir]

One resistor swap can bring the gain up to Thermionic levels, if that's what you wanted to do...

I'd try it "stock" before making any changes though.

Which resistor and what value would one use to get higher gain from the Complex overdrive?

 

[Chuck D. Bones]

If you want to do it "by the book" you change...
R14 to 10K
R16 to 100K (same as Thermionic with the internal trimmer dimed)
C8 to 120pF
C9 to 100pF

Just changing R14 or R16 will get you half-way there.
Changing both will get you to the Thermionic's gain.
Changing the caps will brighten it up a tad to match the Thermionic.