Fuzz War Mk 1 Topic is solved

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Sesh
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Post by Sesh »

I'm making a Fuzz War mk 1 - 7 transistor version - for a friend - the pcb is from Pcb Guitar Mania via a musikding kit.

So I know it's chaotic, unstable fuzz. So unstable that DBA completely remade it as a Big Muff variation for mk 2.

I've soldered it and tested it with my test pedal - it sounds great, I'm pretty sure the fuzz sounds like it's supposed to.
However, I'm experiencing two potential issues: the volume knob when lowered cuts the tone.
The tone knob, modded from the original to the Green Russian Big Muff tone stack doesnt do a whole lot.

Here's the unmodded schematic :
https://pcbguitarmania.com/wp-content/u ... g-Docs.pdf

My question is.. is the the tone suck just a result of my amp (Yamaha Thr 5 /w headphones) being pushed less? And how drastic should a Green Russian tone stack be on such a saturated fuzz? (I'm considering changing it to the original tone stack described as more of a "Character" knob)

Also.. do I need to connect all ground outputs on the pcb for it to work properly? (There's 4 in total it look like) I'm used to vero where there's usually only one collective ground wire.

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Ichabod_Crane
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Post by Ichabod_Crane »

I don't know this fuzz, but looking at the schematic I can tell you something about the Volume. The wiring is unusual, and for some reason it doesn't work on my software emulator, so I can't be sure about I'm going to tell you. Anyway, I see that it brings to the ground not the output but the circuit, and it adds the resistor (pretty high because the 1M pot Volume). I imagine this resistance makes the sound a bit muddy while you cut volume.
About the tone, again, I don't know the effect, but seeing the emulation I can tell that at min setting you should get a bass boost and a treble cut. At half setting it should sound full enough, and at max you could notice a more flat sound, maybe less volume, and I don't know if you really can hear more treble, because this can't gent a treble boost, but just less roll off, though it's pretty large, and maybe it doesn't make too much difference in the normal guitar spectrum.

If you want to change the tone stage you can change C7 and C8, R17 and R18. Look at the tone stage of the Big Muff version you want. You can consider to leave out C9.
Socket those parts if you want to make some experiment.
Remember this is not a Big Muff, I can't see the same filter that the Big Muff has. I mean this fuzz could work differently with the same tone of the Big Muff.

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plush
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Post by plush »

The volume pot wiring is incorrect
It should be wired like this

I dunno if this is designer's flaw, or someone, who was tracing it, was smoking crack.

Also, the tonestack values is a mess...
Attachments
vol wiring.png
vol wiring.png (4.97 KiB) Viewed 2972 times

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Intripped
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Post by Intripped »

In this circuit the volume pot is actually used in that way, there's not an error in the schematic.
if i remember correctly, someone said that this unusual connection keeps the output impedance the same, despite the pot's wiper position.
...however seems to me that the output impedance is too high, and this could be a problem when you connect this circuit to a relatively low input impedance device (amp or other pedal).

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deltafred
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Post by deltafred »

Any circuit that uses transistors the wrong way round immediately raises a red flag to me (as does stacking op-amps) as it shows a basic lack of understanding of electronic theory so anything else doesn't surprise me one bit.
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