Red Army Big Muff Clone build

[Aniol1349]

Hey everyone!

Let me introduce myself as this is my first serious post here, I'm a 25 year old studio engineer and a audio electronic's enthusiast, I've done few pro audio gear builds and I'm modifying my console at the moment, but I still lack in experience and knowledge big time.

Someone approached me today and asked me If I could clone a Red Army Muff for him, as he's got a original one with a broken foot switch and would like to have another one to use it on stage.

Below I'm presenting the schematic of this pedal.


My question is if someone could give me a brief explanation of the behaviour of this circuit.

Second thing is sourcing the parts, I already got the right transistors, on the schematics say Mylar caps, are these for the whole circuit or just de decoupling caps or which ones?
I also read that I could replace the diodes with modern equivalent as it wont make much different to the sound.

The third main thing is what would be the easiest way to copy the circuit board layout? Is there a software in which I could input the schematics and it would give me the layout?

I think that's all the questions I've got at the moment, if there is something crucial I should be worried about please point this out as well.

Thanks

Hubert

[closetmonster.]

The site where that image came from has a tonne of good information about the Big Muff circuit.



As for copying the circuit board, it would be easier to get a more modern one from Tonepad or the like, unless you're experienced in etching your own PCBs.

[splice]

If you're feeling a bit lazy, Kevin over at Aion Electronics has a nice PCB for Big Muff Pi builds and some nice project documentation to go along with it, building a Red Army variant would be a piece of cake with that. I have a few of his boards here and I'm just waiting on parts to come in, going to build a Green Russian variant (same as Red but for some cap values).

As for the film caps, they'd probably cover all cap values from 1uF down to 1nF. Smaller will be ceramics, bigger will be electrolytic. That's pretty much what I go by. 1uF could be electrolytic as well, but yeah, I really like those panasonics 1uF caps... For the diodes, 1N914s are easy to source. Can't say how much effect other diodes could have, that may be a subjective thing to some.

[bloxstompboxes]

Hubert, I actually just sold a 3 Knob Foxey Lady pedal on eBay, my first sale outside of work btw, and I made the board to fit this circuit as well. They are basically the same circuit just different component values and the lady just omits a part. If you want to try etching your own board, I can post the PDF of the layout to use. It will fit snugly into a 125B size enclosure. It has reverse polarity protection, power supply filtering, and a pulldown resistor added. I actually built the Violet Ram's Head on it using the schematic from the same site you got this one from. I think my reference designators for some of the components was different though. But it wouldn't be hard to change them. just time consuming.

To your second question, a lot of us here use DIYLC to make our board layouts; I did for mine. You could also use Eagle and many others. Eagle can be quite complicated and take a while to get use to where as DIYLC was created by Bancika, I think, from this site and is dedicated to mostly drawing pedal circuits. Any which way you go, you would still have to layout where the parts go on the board and route the traces. Mine is done, but there's the reference designator thing. R1 for me might be R4 on this schematic and so fourth. Do a search here and you might find a layout already done, but then again the reference designators.

As for the diodes, in many circuits they make a huge difference in sound since they are basically clipping the signal. For example, a germanium vs a silicon diode will have a big difference. Stick with 1n914s or 1n4148s. for this one.

[nate77]

+1 for the aion electronics board. Kevin arguably makes some of the most well thought out boards available with documentation for various versions and mods for set of his offerings. He has 10 projects PCBs (I believe) and I think 3 pedals he builds and sells complete himself and all he has to offer are of paramount quality. Etching a single sided board or working up a vero or perfboard version will work, but with a pro quality board with board mounted pots you'll get more life and durability out of the build. I've built and sold dozens of boards from Kevin and am always happy ( as are my customers).  This circuit has been done over and over, and the difference is largely the components, so I would look into that route. Good luck.

[bloxstompboxes]

Let's not forget about tonepad's big muff pi PCBs. The have just the mask too, of course.

[mth5044]

As has been said, you can use almost any 4 transistor (which is the large majority) muff PCB, as long as it has a schematic to go along with the layout. Compare your schematic to the supplied one and make the necessary component value changes. It's highly likely that the circuit itself will be exactly the same, but with varying part values.

I'll +1 tonepad's pcbs.

[Aniol1349]

Thanks for all the replies!

I'm really glad the ready made pcb's are going to fit this design variation.
Right now I think I know everything I needed to start on this project.

Once again thanks everyone and I will definitely let you know how did it turned out!

Cheers

[Aniol1349]

Hey guys,

I'm still gathering all the parts and info and I'm stuck on the 430pf feedback capacitors, I wanted to keep the parts as close to the original ones as possible and I can't really find those rectangular brown caps.
Does anyone have a suggestion to which caps I could use for this project?

Thanks

[PBE6]

I would suggest just using plain ceramic caps, I've built a few Big Muff variants with these and they sound identical to me. If you can't find 430pF use the closest standard value of 470pF, it's within 10% of the value and will sound just fine.

[antonis]

I'm still gathering all the parts and info and I'm stuck on the 430pf feedback capacitors, I wanted to keep the parts as close to the original ones as possible and I can't really find those rectangular brown caps.

As you can see in a lot of schematics, there is NO "original" values for various components of BMPi..
(they depent on the respective version..)

If you deal with relative small diference in values you can use the nearest commercial value (390pF or 470pF for a 420pF cap) with no audible results..

[duck_arse]

a 390pF in parallel with a 39pF gets you 429pF, +/-. is that close enuff?

[antonis]

a 390pF in parallel with a 39pF gets you 429pF, +/-. is that close enuff?

I should suggest the parallel combination of 390pF and 33pF in series with 68nF...

[aron]

If the person is really picky, it's possible that no matter how close you get the circuit, he will think it's different. I'm interested in the outcome for sure!

[digi2t]

Hey guys,

I'm still gathering all the parts and info and I'm stuck on the 430pf feedback capacitors, I wanted to keep the parts as close to the original ones as possible and I can't really find those rectangular brown caps.
Does anyone have a suggestion to which caps I could use for this project?

Thanks

You can use 430pF silver mica's. The come in a brown jelly bean package, which retains some of the mojo-tastic esthetic.

Search Ebay, you'll find lots of tasty looking 430pF caps.

My Civil War Muff uses two 1nF caps in series to get 500pF. I just used single 500pF caps in my clones.