Bellum Fuzz MKII Build

[Jiberjew]

Hey guys! I'm fairly new to pedal building. But have built a handful of pedals with little to no issues. I love the fuzz war, so decided to build this circuit. It works, however, i ordered 390k resistors instead of 390r (ohms). I had some 330r (ohms) on hand and stuck these, with sockets, in place of the 2 - 390r (ohm). When i play my guitar through it, it clips when the everything on the pedal is maxed out. Even is just the fuzz is maxed out it will clip as well. Is this due to the 330r in place of the 390r? Or do I have a bigger problem? Heres a link to the build sheet :

https://docs.pedalpcb.com/project/BellumMKII-PedalPCB.pdf

I appreciate any help and thanks everyone in advance!

 

[habitatsombre]

Hey guys! I'm fairly new to pedal building. But have built a handful of pedals with little to no issues. I love the fuzz war, so decided to build this circuit. It works, however, i ordered 390k resistors instead of 390r (ohms). I had some 330r (ohms) on hand and stuck these, with sockets, in place of the 2 - 390r (ohm). When i play my guitar through it, it clips when the everything on the pedal is maxed out. Even is just the fuzz is maxed out it will clip as well. Is this due to the 330r in place of the 390r? Or do I have a bigger problem? Heres a link to the build sheet :

https://docs.pedalpcb.com/project/BellumMKII-PedalPCB.pdf

I appreciate any help and thanks everyone in advance!
cluster rush

I tried building a similar pedal but I used a 390r resistor and it worked fine. Maybe you should try changing 330r to 390r and put it in its correct position. It's been a while so I don't remember exactly what my build table looked like. I'll try to find it again and if I find it I'll send it to you

 

[Jiberjew]

I tried building a similar pedal but I used a 390r resistor and it worked fine. Maybe you should try changing 330r to 390r and put it in its correct position. It's been a while so I don't remember exactly what my build table looked like. I'll try to find it again and if I find it I'll send it to you

Awesome. I did change it out to the proper resistor, but I still have a strange clipping sound when I crank up the fuzz and tone pots. Not sure why, I'll have to dig into it. Might be the characteristics of the pedal too, as I've never tried a fuzz war pedal yet. Thanks for your help!

 

[airbud]

Hey guys! I'm fairly new to pedal building. But have built a handful of pedals with little to no issues. I love the fuzz war, so decided to build this circuit. It works, however, i ordered 390k resistors instead of 390r (ohms). I had some 330r (ohms) on hand and stuck these, with sockets, in place of the 2 - 390r (ohm). When i play my guitar through it, it clips when the everything on the pedal is maxed out. Even is just the fuzz is maxed out it will clip as well. Is this due to the 330r in place of the 390r? Or do I have a bigger problem? Heres a link to the build sheet :

https://docs.pedalpcb.com/project/BellumMKII-PedalPCB.pdf

I appreciate any help and thanks everyone in advance!

try using a 470R; if the 330R is too much signal, then the 470R should be not enough. use what you have on hand that's bigger than 390R, it's just to help zero in on whether you just need 390R or if it's something else. also, you can chain two resistors (330R and maybe 56R or 68R).

the values I picked were based on what came with the resistor variety pack I got off Amazon; if you haven't got one it's a lot of bang for your buck.

hope that's helpful! I built one of these and love it.

 

[GizzWizzKing]

It sounds like your diodes might be leaky? I think mine does this too since I used some Russian D9 diodes. I could be reading your symptoms incorrectly though. I believe there are others who have talked about this on the forum. Maybe searching the troubleshooting forum for other Bellum builds will be of some help.

 

[ianmarks]

I think those are basing the transistors and lower values typically increase the gain. If you don't have the exact value you can put a couple of resistors in series (they add together so 2 220r would equal 440r,) or parallel which is a little more complicated math wise, but two of the same value is half. So two 820r in parallel would be 410r. You can use an online resistor calculator for the parallel values to figure out that combos.

 

[micmac]

I don't really understand the first post. It says the pedal clips when everything is maxed out. Isn't a fuzz supposed to clip the signal?!

Anyway, maybe it works just fine but it's not what you expected. Check this thread, even comes with sound samples:

Link

 

[Jiberjew]

try using a 470R; if the 330R is too much signal, then the 470R should be not enough. use what you have on hand that's bigger than 390R, it's just to help zero in on whether you just need 390R or if it's something else. also, you can chain two resistors (330R and maybe 56R or 68R).

the values I picked were based on what came with the resistor variety pack I got off Amazon; if you haven't got one it's a lot of bang for your buck.

hope that's helpful! I built one of these and love it.

I’ll give this a try. I did get a massive resistor pack on Amazon, that did have a 390R and still has a lot of clipping. Also, the clean signal cuts through the fuzz if I strum normally. If I lightly strum, the fuzz is present and sounds good. Hope that makes sense.

 

[Jiberjew]

I don't really understand the first post. It says the pedal clips when everything is maxed out. Isn't a fuzz supposed to clip the signal?!

Anyway, maybe it works just fine but it's not what you expected. Check this thread, even comes with sound samples:

Link

I’m probably not explaining this correctly. When maxed out, the clean is more present than the fuzz. And the tone cuts out when I strum normally. I guess it wouldn’t technically be clipping, more of cutting out. Diodes might be an issue. I did socket them to mess around with different diodes, so maybe I’ll look into that. And you may be correct about it not being what I expected. I’ve heard the fuzz war, not sure if it’s the MK1 or MK2 (it’s basically what everyone is reviewing on YouTube), and it sounds great! Mine sounds nothing like that. I’ll check out the link you posted, maybe that’ll help. Thanks for the link and advice.

 

[Jiberjew]

It sounds like your diodes might be leaky? I think mine does this too since I used some Russian D9 diodes. I could be reading your symptoms incorrectly though. I believe there are others who have talked about this on the forum. Maybe searching the troubleshooting forum for other Bellum builds will be of some help.

Thanks! I’ll dig a little deeper. I’ll also swap out the diodes. I’m using what’s on the BOM. But, I have tons of diodes either way to try. I did socket the diodes to change them out as well. I’ll check them later today to see if they are leaking.

 

[jwin615]

The FWv2 is just a modded muff/STB. There should be no clean signal. Check you in/out wires and pads for any bridging. If you're getting clean signal leaking through, you likely have a bridge. Or a funky switch contact.
If all that looks good, I'd audio probe each collector to split the circuit up.

In regards to the diodes, since the v2 only uses 1 pair of clippers, if one, or both, have an intermittent connection via the sockets, you could get some changes in tone, from lower volume/more distorted (diodes in circuit) to higher volume/less distortion (diode out). 1n34s have a low Vf, so it should be a pretty noticeable volume difference.
If only 1 diode is dropping out, you'll only clip half the waveform, sounding kinda clean, kinda distorted.
A simple test would be to pull the diodes and play through it. If *that's* the sound you're getting, root cause is likely poor connection of the diodes. Or pull one, then pull both.
Hope this helps.

 

[Jiberjew]

The FWv2 is just a modded muff/STB. There should be no clean signal. Check you in/out wires and pads for any bridging. If you're getting clean signal leaking through, you likely have a bridge. Or a funky switch contact.
If all that looks good, I'd audio probe each collector to split the circuit up.

In regards to the diodes, since the v2 only uses 1 pair of clippers, if one, or both, have an intermittent connection via the sockets, you could get some changes in tone, from lower volume/more distorted (diodes in circuit) to higher volume/less distortion (diode out). 1n34s have a low Vf, so it should be a pretty noticeable volume difference.
If only 1 diode is dropping out, you'll only clip half the waveform, sounding kinda clean, kinda distorted.
A simple test would be to pull the diodes and play through it. If *that's* the sound you're getting, root cause is likely poor connection of the diodes. Or pull one, then pull both.
Hope this helps.
View attachment 74963

Great advice! I’ll definitely try that later today. I do get clean up front and fuzz in the back, if that makes sense. I definitely think something is wrong. And it definitely could be a bridge somewhere, and I’ll probe around to check that. This is my third build, so I’m still getting the hang of soldering. For sure could be something on my end. The diodes did seem to be a little loose in the sockets as well, so there could be an intermittent issue as well. Thanks again! This definitely gets me on the right track. I think the build I wanted to do was the fuzz war 1, or bellum MK1. So, I think I’ll grab one and build it. I’m having a great time building them and need the practice anyhow.

 

[Untro]

Ive heard that transistor matching is important for the bellum, biasing and looking for a lower forward voltage drop? I havent built it, its been sitting in my todo bucket for about a year because my impression is that its a pretty finicky circuit.

 

[Jiberjew]

Ive heard that transistor matching is important for the bellum, biasing and looking for a lower forward voltage drop? I havent built it, its been sitting in my todo bucket for about a year because my impression is that its a pretty finicky circuit.

It is a bit finicky. My next move was biasing the transistors. I swapped diodes, and it helped a bit. But when I crank the pots, but leave the volume at about 1/4 the way up, it starts cutting out and popping kind of. I’ll probably move on to my next build and leave that guy on the back burner. Im really just trying to find a fuzz pedal I like. I may have went the wrong route with this one. But, all good. It was still a fun build over all. I like the tone benders, zonk’s and fuzz face tones. So, I’ll keep building until I find one I like and sell off and give away the ones I don’t haha. Thanks for the advice though!