Speaker Cranker Build Help

[firestorm119]

Hi everyone, I'm just getting back into pedal building and as a first new project I'd like to try and build a clone of the Earthquaker Devices Speaker Cranker. I haven't found any schematics online but I did come across one image (a still I ripped from a youtube clip) that shows the top side of the circuit board:



Zoomed:



As you can see, the circuit is pretty simple, there are only 15 components on the board (4 caps, 5 resistors +1 pot, a transistor and 4 diodes) and I was hoping I might get some advice on the what the components might be and possible circuit layouts. I feel like the picture has enough info that some simple guessing by educated builders (aka not me) could probably get pretty close.

Or maybe someone around here has one and can open it up and tell us what they see :]

This is what I've compiled so far:
- The bottom-left-most capacitor in the bottom right reads 200uF
- The resistors are pretty obvious
- The left side shows that the pot is a 10k Lin
- The three diodes might be part of the op-amp chain (?)

Any ideas or suggestions would be greatly appreciated! Thanks!

[Mike Burgundy]

Opamp chain? Where's the opamp? ;P
Without the trace side, its impossible to say what connects to what. It is obviously a single transistor gain stage, I guess the 3 diode cluster are for (asymmetrical) clipping. Circuits like this simple are easy to whip up, but really need the details to shine - if you have a breadboard, set up single transistor gain stages, feeding clippers to ground and experiment. Chances are you'll come up with something that's cooler for *your* setup and wishes.

[Pyr0]

I believe this is based on the old Electra Distortion, and uses modern 1N60 diodes on the output for asymetrical clipping. It has an extra gain control similar to the fuzz control on a fuzz face. There is a schematic and vero layout floating around somewhere, maybe on the other forum. 

[Johan]

As pyro said, probably based on the electra. And at mike says, without traces impossible to say..search for cot50 for something similar but with a knob( if the electra is truly what it is)
J

[midwayfair]

It's an electra, and it was traced ... "elsewhere." The EQD guys actually confirmed and corrected some stuff for the tracers in that thread.

[duck_arse]

why is "it" always referred to as "the other forum/place" or similar? is there bad blood?

firestorm, those blue bodied resistors are never "obvious". I've been looking at them for 30 years, and still can't tell the colours apart.

[wavley]

why is "it" always referred to as "the other forum/place" or similar? is there bad blood?

firestorm, those blue bodied resistors are never "obvious". I've been looking at them for 30 years, and still can't tell the colours apart.

I agree on the resistors, for some reason I always have trouble reading them too.

I would just use the search function on the other subject, it's been discussed ad nauseum around here, there is no real reason to bring it back up.  It basically boils down to a difference in approach, many folks around here are members of both forums and all are good people.  Honestly, while I have a preference for here, the world needs both forums.

[firestorm119]

Thanks for the input everyone! I had no idea about the 'other forum' or the history between the two. I'll try to be more careful/sensitive in the future. Unfortunately I'm having some issues getting registered there so I haven't been able to see the thread everyone is referring to... Maybe they think I'm a spam bot 

As Mike jokingly pointed out, I obviously have a lot to learn but I appreciate all of your help. While it's fun to recreate a couple pedals, I'd really like to start learning how to build my own from scratch; I feel like this forum is a good place for me.

[wavley]

Thanks for the input everyone! I had no idea about the 'other forum' or the history between the two. I'll try to be more careful/sensitive in the future. Unfortunately I'm having some issues getting registered there so I haven't been able to see the thread everyone is referring to... Maybe they think I'm a spam bot 

As Mike jokingly pointed out, I obviously have a lot to learn but I appreciate all of your help. While it's fun to recreate a couple pedals, I'd really like to start learning how to build my own from scratch; I feel like this forum is a good place for me.

Welcome! By the way.

Quite a few folks around here have built the electra, I'm sure if you do a search you'll find a lot of stuff on it.  I highly recommend reading the wiki, it's a really great place to start, also the beginner tutorial is a single transistor boost much like the electra but without the clipping diodes, you might have a look at that.

Everybody is always willing to help out where they can here, don't be afraid to ask questions.

[mauvehead]

Howdy All...

This is my first post here. I own a Speaker Cranker and have always had issues with it picking up signal from a local FM Radio tower (I live less than 1 mile from the tower). This pedal looks pretty simple and so I was wondering if perhaps I could hotrod any of the components to filter out the stupid radio signal? I have a slew of other pedals, everything is powered via Voodoo Labs power supplies with all pedals being fed its own dedicated isolated power, and the Voodoo Lab is receiving clean/filtered power from a studio power conditioner. I also have a Radial ToneBone Classic and a modded SD TweakFuzz (I removed the R4 for more volume), both of which will sometimes pick up the radio station as well, but other than that I don't have any radio issues with any of my other pedals, including plenty of other fuzzes, distortions, OD's, boosts, etc.. If helpful I can snap a couple pics of the Speaker Cranker's board (both sides) to get the wheels turning here. But I'd really like to keep this pedal as I like how it boosts the low mids when using bigger speaker cabinets (think Orange-size cabs).

Thanks in advance for any help that can be offered!

Cheers...

Todd

[smallbearelec]

I'd really like to start learning how to build my own from scratch;

If you like, you can breadboard my Ursa Minor, which is a heavily modded Electra--better control of distortion and more output.
https://www.smallbearelec.com/HowTos/BreadboardUrsaMinor/BreadboardUrsaMinor.htm

Then when you are happy with the tone, you can re-use the parts to build the boxed version:

https://www.smallbearelec.com/Projects/UrsaMinor/UrsaMinor.htm

Regards
SD

[duck_arse]

mauve, here is a circuit diagram marked "electra distortion". I dunno, but it says ^above that your speaker crank thing is something of an electra. it matters not, what you need to do is find the left most 0.1uF cap (or its equivalent) and insert a small value resistor, start at 100R, keep going till it works, and a small value ceramic cap, start with 47pF maybe, between the new resistor and the original cap, with the free end of the new cap to ground. this should form an rf filter.


the same principle applies to yr other radio pedals.