Big Muff Pi V3 (Red and black) questions

[DeusM]

Hi guys! So, I'm going to make my firs full hand made pedal and I choose the big muff. I've already made a prototype of a simple fuzz that worked well on the breadboard and now I what to go further. So I've been reading a lot about the Big Muff from Kit Rae's page witch is like a bible of the pedal. http://www.kitrae.net/music/music_big_muff.html
I decided to make the V3 of the pedal, the original red and black because of the sound, the other version didn't seem to have as much sustain and response to pinched harmonics witch are two things I like about distortion. So since it's my first pedal and there are so many good people here willing to answer  I decided to see if you guys can help me with some doubts. So here is the schematics for the pedal:



So, for the transistor I only could get 2N5088 witch is also used but my question is: should I change the values of some components if I use these transistors? I can also get 2N5089 and 2N5087 and also MPSA18. I would like to try them all but i don't know if i should change something more.

My other question is, if I want to make it true bypass, do I have to change something else in the basic schematic or just with wiring the 3DPDT the right way ill be fine?. Also, I would like to add a led, that's why I'll be using a 3DPDT.

Also, I'm not sure what layout to use. I think the best choice will be to make the diagram in some software and then let it make the layout.

I'm new into this so I'm sure these questions are very basic, but I'm willing to learn more and more, and I'm reading a lot about electronics to keep learning. My goal is to keep making pedals and hopefully sell some in the future because it's a subject that i really enjoy.

So, thank you guys and I hope you could help me understand more about these things.

[Plexi]

Answer your question about the transistors: I don't think that you'll need to re-biasing them.
Just put sockets, and try; it'll be fun and will solve all your doubts.

Answer your question about the layout and true bypass, use this proyect:
http://effectslayouts.blogspot.com.ar/2015/08/electro-harmonix-big-muff.html

There you have everything you'll need: added pullout resistor, invert polarity protection, adding led, etc.

Have fun 

[DeusM]

Hey man!! Thanks for that!! A lot of info and full schematics with layouts. Although, It doesn't say it is for the V3.  But anyway. I'm not sure that the V3 version is any different in the schematics. I think it doesn't so I will try that one and try different components to see what I like the most. And also I don't think I will only build one!!! The reverse polarity protection also is a big plus!!
So again.Thank you!

[Plexi]

You're welcome DeusM!

It's easy.. you have to find that components and replace them.
I'll see that version later and try to find out where components you have to change.
Remember use sockets where all the critical components are 

[Kipper4]

2N5087's are PNP
The schematic calls for NPN and probably something with a lesser Hfe than the 5088,5089 or even the mpsa18.
Search for big muff transistors on the forum, someone might have tried this already.
Like I know anything about fuzzes anyway.......
Breadboard and transistor auditions might be in order before you make a populated pcb.

[DeusM]

2N5087's are PNP

Oh yeah! You are right!! Thanks for letting me know before I make something blow up.

The schematic calls for NPN and probably something with a lesser Hfe than the 5088,5089 or even the mpsa18.

I'be seen some schematics of older Big Fuzz with PNP anyway, I think the older versions before the V3 used this types of transistors.

Some schematics I read say to use 88s but I'm not the guy to say if its wright or not. Something I read is that to make a difference in the sound you have to change many components. So maybe the transistors only have a little role in the overall sound? Hope I don't sound stupid, but I read in many pages including Kit Rae's not many complains about the transistors. I'll check out about muff transistors anyway so thanks!

Breadboard and transistor auditions might be in order before you make a populated pcb.

Definitely!! Not thinking about putting a case into it before tenstings in the breadboard and see how it sounds with different components. So many thins anyway to learn, like how to wire certain things like the pots and the switch, and the jacks, and also how to correctly implement a 9V jack and filter the noise of it.



Here is another diagram from the page. It uses NPN too but some values are different.




And here is the schematic with the 87

Remember use sockets where all the critical components are 

Didn't know about those for transistors!!! That's nice! Now I don't have to worry about burning them when mounting
Although I'm joking I don't know if you guys recommend me to use sockets in the PCB or solder all the transistors. I know there might bee a risk of it falling or something if the pedal falls to the ground or something.

[Plexi]

It's true that they're more vulnerable than any other components, but don't worry too much.
I recomend use sockets because, if you're extremealy curious like me, you want to try/combine/match any NPN transistor you have on hand.

My fav Muff it's my first one: I used sockets, and try a lot of transistors.
Remember the hfe, and combine them.
I used KSP13 (MPSA13) in the output to have more volume.
Used KSP13 in both gain/clipping stages to get more gain, and a mid gain transistor (2N3904, BC548, BC549) in the input stage.

Try mid or low transistors in both clipping stages and input stage to get mor subtle gain/tone (like many russian muffs), and some high gain/output transistor in the output stage to get more volume.


There you have:

Source: http://www.coda-effects.com/2015/11/big-muff-mods-and-tweaks.html

The Muff uses four transistors and the type and choice of these transistors will affect the sound greatly. The higher the gain, the more the unit will focus on the high end / treble. Some known examples: The Russian Muff uses E type transistors (newer ones use BC549C's though) which has a Hfe of around 500. I used BC184's as a great replacement of these transistors. The NYC Muffs usually use 2N5088's or BC550's with a Hfe of around 800. The Little Big Muff uses 2N5962 with a Hfe of around 1500 - 2000. The Russian sounds darker due to the low gain. Knowing this, we can change the sound of a muff greatly by replacing the transistors. Small tip: use sockets when changing transistors. This way the transistors are not damaged by the soldering and swapping is much much easier. Some nice ones: 2N5133's: used in Triangle ones (the NOS versions tend to sound even better then newer ones) as FS36999's. Very nice sound, smooth, warm, open.One of my favs! Note from Coda Effects: I would not use these ones. They are really rare and expensive. I am not sure that they really sound better... I would try to find something similar in hfe (around 100-400). BC239's: also used in a bunch of Muffs around. Slight less gain as the above named but this gives the Muff quite a nice touch. 2N5087's: PNP transistors instead of the above named NPN (more usualble). To use these you need to reorient some of the caps and change the + and - of the battery (called positive ground). Although they must be identical to 2N5088's they were used in some old models and do sound different. BC141's: ultra low Hfe (around 100) and not suited for anyone out there. More bass, less gain but a very different sound. MPSA13's: ultra high Hfe (around 10.000). Nice touch for some more gain. Experiment! Use four of the same transistors or try to mix. For example I like a Muff with 5133's for the clipping stages and MPSA13's for the buffer stages. Note from Coda Effects: I also experimented with a few transistors, here is my feedback about this: The first transistor is the one that will define the most of the gain of your unit. Higher hfe = more gain, but also more trebles... I tried a few ones: 2n5089: high gain, but also gives a "gritty" touch to the muff that I do not really like. Also quite noisy 2n5088: nice sound, gainy unit, but less noisy and agressive trebles than 2n5089. I really like it and use it often. 2n2222A: low gain, gives more bass and smoother sound. Beware: polarity is reversed compared to 2n5089. MPSA18: extreme gain! I would suggest to increase emitter resistor to limit gain (especially for noise issues), but you can have a nice "doomy" muff with it! 2n3904/BC549C: great for a low gain Muff. The two transistors of the gain stages play a bit more with compression. I usually use low hfe. 2n2222 are really nice for this use. 2n5088 can also do the job. The last transistor will define the final output volume of the unit. I like to have quite a lot of output volume, so I prefer to use high hfe transistor for the last stage, like 2n5089, or MPSA18.

[DeusM]

Oh man! I'm gonna have to change my order again to add some extra transistor 
thanks a lot for the info. I'm so exited. Can wait to see If I can make it work first and then see how it sounds. The socket thing is a nice info. I thing ill try it solder in the PCB to get experince but they will definitli be on the bredboard beacuse i always end up with bended transistors.
It will take me a couple of weeks until I get the orden and then stars making it but I will definitly post the resuls so stay tuned!
And thanks again!! This is a great comunity.

[duck_arse]

Deus! save yourself a lot of trouble, for EACH transistor type you get in your hand, collect the datasheet for as well. [how good is my english?] and then make a little diagram of the pinouts of each transistor on your circuit diagram (you do draw yourself a diagram, don't you?) so that you can just pick them up and plug them in, without worrying about backwards and end base connections, etc.

have fun! oh, and your OP question about true bypass - that first circuit diagram shows true bypass switching, you just add the extra switch pole of your 3pdt and a led and a CLR and a voltage source.

[Plexi]

Great advise Duck!

So, which layout will you use? Let me know and I'll search for components changes.

[DeusM]

Deus! save yourself a lot of trouble, for EACH transistor type you get in your hand, collect the datasheet for as well.
and then make a little diagram of the pinouts of each transistor on your circuit diagram

Great advise!!!!

(you do draw yourself a diagram, don't you?)

Uuhhhhmmm yeahhh... sure 
Seriously I'll start doing that.
I have downloaded some programs for making diagrams that I'll be using so I can make my own layout.

you just add the extra switch pole of your 3pdt and a led and a CLR and a voltage source.

Uhh  I'm new so I dindt quiet undertood all of that but don't worry!!! I have a lot of articles I save for reading about true by pass and other stuff as well. Right now I'm studying for some finals so I don't get time to read about all I have to read to make the pedal right.

So, which layout will you use? Let me know and I'll search for components changes.

I'll be usgin the one thats on the page you recomended me!!! 
It has like you said, reverse polarity protection and LED as well in it.
Also ut has the layouts but I think I'll be using my own.
I ordered a BB case for the pedal, not knowing it was so big 
But, hey, it will be easier for me that way.

EDIT: You asked for the layout right? Not the schem?
I'm probably gonna use multisim to recreate the schematic and from there the make a layout, beacuse I'm having some trouble trying figuring out the schematic.
Heres the ones I have


longer version. although I think both will fit perfectly in the case.