Digitech - Bad Monkey  [schematic]

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
User avatar
touringbubble
Information
Posts: 38
Joined: 16 Oct 2015, 14:26
Has thanked: 2 times

Post by touringbubble »

I'm working on my understanding of what all of the components do. Your input helps. Thanks!

User avatar
Ice-9
Degoop Doctor
Information
Posts: 1094
Joined: 31 Mar 2009, 15:29
my favorite amplifier: Marshall
Completed builds: Far to many to afford the enclosures for them all. :)
Has thanked: 134 times
Been thanked: 359 times
Contact:

Post by Ice-9 »

touringbubble wrote:I'm working on my understanding of what all of the components do. Your input helps. Thanks!
To recognise and understand the bypass switching in this pedal have a look at R.G. Keens The Technology of JFET Switching in Boss and Ibanez Pedals at http://www.geofex.com It is explained very well.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

User avatar
touringbubble
Information
Posts: 38
Joined: 16 Oct 2015, 14:26
Has thanked: 2 times

Post by touringbubble »

Thanks for the info everyone! I'll definitely look into those resources.

Would anyone happen to have a value for C31 (power adapter)? That seems to be the last missing piece of the schematic. I've made a modified schematic to account for all of the discussion in this thread that I'll post once I get that last value. Maybe someone else can get benefit from it too.

User avatar
touringbubble
Information
Posts: 38
Joined: 16 Oct 2015, 14:26
Has thanked: 2 times

Post by touringbubble »

touringbubble wrote:Would anyone happen to have a value for C31 (power adapter)? That seems to be the last missing piece of the schematic. I've made a modified schematic to account for all of the discussion in this thread that I'll post once I get that last value. Maybe someone else can get benefit from it too.
Just following up ... I admittedly have no idea what I'm doing, but I think a 47u could work for C31. Any opinions?

User avatar
Ice-9
Degoop Doctor
Information
Posts: 1094
Joined: 31 Mar 2009, 15:29
my favorite amplifier: Marshall
Completed builds: Far to many to afford the enclosures for them all. :)
Has thanked: 134 times
Been thanked: 359 times
Contact:

Post by Ice-9 »

Frank_NH wrote:
touringbubble wrote:Hi everyone! I'm just now getting in to building and am getting a lot from browsing the forums here. Thanks a ton for all the schematics and tips!

I had a question about the Bad Monkey schematic here. I've been looking at schematics of pedals that I'd like to try out, and this was on the list. I can tell it's a bit more complicated than a standard boost pedal, and I can appreciate that at my non-existent skill level.

If I wanted to build the main instrument circuit of the BM without the emulated output, would it be as simple as not building the circuit for the speaker output and simplifying the adapter circuit to match a standard +9v setup? Or, is that power schematic important for the proper voltage to the main circuit?

Thanks for the input!
Here's a bufferless version of the Bad Monkey on vero. I may build this one because it is different than your standard tube screamer. I would probably try using two different diodes (e.g. 1N4148 and a 1N4001) to get some asymmetric clipping as that is my preference for op amp overdrives.

http://tagboardeffects.blogspot.com/201 ... rless.html
The genuine Bad Monkey Schematic doesn't show any cap in that position that I can see, if you really want to use one then anything from 10uf to 47uf is quite suitable. (leave it out - put it in. .. it's up to you)
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

User avatar
touringbubble
Information
Posts: 38
Joined: 16 Oct 2015, 14:26
Has thanked: 2 times

Post by touringbubble »

Ice-9 wrote:The genuine Bad Monkey Schematic doesn't show any cap in that position that I can see, if you really want to use one then anything from 10uf to 47uf is quite suitable. (leave it out - put it in. .. it's up to you)
Ah, okay. Thanks! I'm now learning that caps like that are usually just to clean up noise, so that makes sense.

User avatar
Ice-9
Degoop Doctor
Information
Posts: 1094
Joined: 31 Mar 2009, 15:29
my favorite amplifier: Marshall
Completed builds: Far to many to afford the enclosures for them all. :)
Has thanked: 134 times
Been thanked: 359 times
Contact:

Post by Ice-9 »

touringbubble wrote:
Ice-9 wrote:The genuine Bad Monkey Schematic doesn't show any cap in that position that I can see, if you really want to use one then anything from 10uf to 47uf is quite suitable. (leave it out - put it in. .. it's up to you)
Ah, okay. Thanks! I'm now learning that caps like that are usually just to clean up noise, so that makes sense.
Those caps are not JUST to clean up noise It serves the job as a power supply noise filter AND it rejects AC signals from different parts of the circuit. two jobs but both similar.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

User avatar
touringbubble
Information
Posts: 38
Joined: 16 Oct 2015, 14:26
Has thanked: 2 times

Post by touringbubble »

Ice-9 wrote:Those caps are not JUST to clean up noise It serves the job as a power supply noise filter AND it rejects AC signals from different parts of the circuit. two jobs but both similar.
And that's why they have polarity? Makes sense. Thanks!

User avatar
induction
Resistor Ronker
Information
Posts: 276
Joined: 07 Feb 2012, 20:47
Has thanked: 61 times
Been thanked: 116 times

Post by induction »

touringbubble wrote: And that's why they have polarity? Makes sense. Thanks!
Not quite. The caps have polarity because they are electrolytic. It's not a requirement to use polarized caps here (or ever). Polarity in caps is not a feature, it's a necessary evil. The bottom line is that for large capacitance values, non-polar caps are more expensive than polarized ones.

User avatar
cspar
Breadboard Brother
Information
Posts: 111
Joined: 29 Oct 2020, 21:26
Has thanked: 75 times
Been thanked: 68 times

Post by cspar »

Ice-9 wrote: 04 Nov 2015, 22:39 Those caps are not JUST to clean up noise It serves the job as a power supply noise filter AND it rejects AC signals from different parts of the circuit. two jobs but both similar.
Capacitors block DC and allow AC to pass through.

The audio signal itself is AC.
"Just because the forgoing circuits have produced results there is no reason experimenting won't lead to added results." L. E. Darling, in his article containing the earliest published vacuum tube synthesizer circuit, Popular Science Jan 1920

User avatar
Ice-9
Degoop Doctor
Information
Posts: 1094
Joined: 31 Mar 2009, 15:29
my favorite amplifier: Marshall
Completed builds: Far to many to afford the enclosures for them all. :)
Has thanked: 134 times
Been thanked: 359 times
Contact:

Post by Ice-9 »

cspar wrote: 25 Mar 2023, 16:11
Ice-9 wrote: 04 Nov 2015, 22:39 Those caps are not JUST to clean up noise It serves the job as a power supply noise filter AND it rejects AC signals from different parts of the circuit. two jobs but both similar.
Capacitors block DC and allow AC to pass through.

The audio signal itself is AC.
Yeah, Oops. That's what i meant.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

Post Reply