# Mini-Muffin Fuzz....Not Fuzzy



## bakewelder (Mar 2, 2021)

Preface: Noob here. 

Troubleshooting the Mini-Muffin Fuzz. Passing signal, though only slightly distorted, not fuzz.

After C1, signal drops significantly. Virtually no prob-able audio at inputs of IC (pin 2 or 3). Output of IC at Pin1 is plenty loud, not distorted. Signal at C2 (post diodes and output of IC B)  is distorted but more like slight overdrive, not fuzz. 

Tried a new IC, same results. 

Any suggestions? thanks!


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## bakewelder (Mar 2, 2021)

Pics of the board.


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## BuddytheReow (Mar 2, 2021)

Are your component values correct for C1, R1, and R2? C1 is merely a filter so sound should go through it just fine

Also, where did you get your 1n34a diodes? Just curious since i'm going to make a purchase soon.


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## bakewelder (Mar 2, 2021)

Just double checked, they all appear to be right. C1 smashes the signal. Hmmmm. 

Tayda, before they were sold out.


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## bakewelder (Mar 3, 2021)

BuddytheReow said:


> Are your component values correct for C1, R1, and R2? C1 is merely a filter so sound should go through it just fine
> 
> Also, where did you get your 1n34a diodes? Just curious since i'm going to make a purchase soon.


Where does most of the fuzz get added in the circuit? the 2nd gain stage (diodes and OP Amp B)? Here is a video of how the effect behaves. 


https://photos.app.goo.gl/YAKrgWSK2fWScfnp9


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## BuddytheReow (Mar 3, 2021)

The diodes will provide the fuzz/clipping.


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## Chuck D. Bones (Mar 3, 2021)

bakewelder said:


> Preface: Noob here.
> 
> Troubleshooting the Mini-Muffin Fuzz. Passing signal, though only slightly distorted, not fuzz.
> 
> ...


You won't get any signal at IC1-2 or IC1-3, that's normal.

There are a lot of bogus 1N34As out there.  The ones I bought from Tayda are not Germanium, they're Schottky.  The ones you have look like they _might _be real.  Real Germanium diodes vary a LOT from part-to-part and because of that, not all of them will work well in this circuit.  My guess is the ones you have are too leaky. Take them out, install sockets and try different diodes.  Try 1N4148s to see if that fixes it, then we'll know for sure whether the problem is the diodes.  I recommend always socketing Ge diodes because a) the heat of soldering can easily damage them and b) you're probably going to want to swap them.  If you have any more of that batch of diodes, try measuring their reverse resistance with a DMM.  Measure them both ways and report the higher reading.  

*Attention noobs:* 
Pedals that contain Germanium parts take extra effort because Germanium parts are finicky.  You have to at least be able to try different ones until you get the desired result, or better yet, test them.  Get your Germanium parts from a trusted supplier like Small Bear or PedalHacker.  Tayda may sell some good Ge parts, but the ones they sold me were bogus so I won't be buying any more Ge from them.  eBay is pretty hit-and-miss (mostly miss) so beware.


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## zgrav (Mar 3, 2021)

aside from the difficulty of knowing whether you have good germanium diodes, this was a very good project for a new builder.

I would have thought the volume on each side of C1 would be about the same.   what do you get with your probe at pins 6 an 7?  how does the volume at pin 1 compare to the volume at pin 6 and pin 7?


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## Chuck D. Bones (Mar 3, 2021)

Zgrav, this thing has an extremely low input impedance, so C1 is gonna eat some of the signal.  The other effect of the low input impedance is this pedal will be very sensitive to the guitar's Volume knob.  Make sure it's on 10.

You're not going to get any signal at pin 6 either, that's normal.


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## bakewelder (Mar 3, 2021)

Chuck D. Bones said:


> You won't get any signal at IC1-2 or IC1-3, that's normal.
> 
> There are a lot of bogus 1N34As out there.  The ones I bought from Tayda are not Germanium, they're Schottky.  The ones you have look like they _might _be real.  Real Germanium diodes vary a LOT from part-to-part and because of that, not all of them will work well in this circuit.  My guess is the ones you have are too leaky. Take them out, install sockets and try different diodes.  Try 1N4148s to see if that fixes it, then we'll know for sure whether the problem is the diodes.  I recommend always socketing Ge diodes because a) the heat of soldering can easily damage them and b) you're probably going to want to swap them.  If you have any more of that batch of diodes, try measuring their reverse resistance with a DMM.  Measure them both ways and report the higher reading.
> 
> ...


Thanks for the response Chuck appreciate the time and consideration. I will remove those and socket up some 1N4148s and report back the results.


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## bakewelder (Mar 3, 2021)

zgrav said:


> aside from the difficulty of knowing whether you have good germanium diodes, this was a very good project for a new builder.
> 
> I would have thought the volume on each side of C1 would be about the same.   what do you get with your probe at pins 6 an 7?  how does the volume at pin 1 compare to the volume at pin 6 and pin 7?


I have a dozen or so successful builds under my belt, but starting to go thru the other 4 or 5 that are working properly, so i can get em boxed up. This is indeed the simplest circuit of the bunch, so figured it be good to start honing the trouble shoot skills. 

I broke by probe today, so I will make a new one tomorrow and report back. thanks!


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## bakewelder (Mar 3, 2021)

Chuck D. Bones said:


> You won't get any signal at IC1-2 or IC1-3, that's normal.
> 
> There are a lot of bogus 1N34As out there.  The ones I bought from Tayda are not Germanium, they're Schottky.  The ones you have look like they _might _be real.  Real Germanium diodes vary a LOT from part-to-part and because of that, not all of them will work well in this circuit.  My guess is the ones you have are too leaky. Take them out, install sockets and try different diodes.  Try 1N4148s to see if that fixes it, then we'll know for sure whether the problem is the diodes.  I recommend always socketing Ge diodes because a) the heat of soldering can easily damage them and b) you're probably going to want to swap them.  If you have any more of that batch of diodes, try measuring their reverse resistance with a DMM.  Measure them both ways and report the higher reading.
> 
> ...


measured 3 of the 8 I have left - .279, .289, .292


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## Chuck D. Bones (Mar 3, 2021)

OK, you have measured Vf. Now reverse the meter leads and measure their reverse resistance.  Good ones with read over 500K.  Don't touch the leads when making the measurement or you'll be measuring your skin resistance.


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## bakewelder (Mar 4, 2021)

Chuck D. Bones said:


> OK, you have measured Vf. Now reverse the meter leads and measure their reverse resistance.  Good ones with read over 500K.  Don't touch the leads when making the measurement or you'll be measuring your skin resistance.


35k-40k Ohms. Had a couple outliers that were higher or lower.


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## Chuck D. Bones (Mar 4, 2021)

That supports my theory that diode leakage is the root cause for why your pedal sound "is distorted but more like slight overdrive, not fuzz."  We'll know more when you replace the diodes.

Have you tried testing this pedal with a different guitar?

Another possible cause comes to mind, so bear with me here.  Have you heard a demo of the real pedal?  It is possible that this pedal is working normally and your expectation of how it should sound is incorrect?


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## BuddytheReow (Mar 4, 2021)

YouTube can be very misleading at times


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## zgrav (Mar 4, 2021)

The audio sample posted above sounds pretty tame to me, but it could be affected by the incoming signal.  What kind of guitar are you using?    Have you tried it with another pedal in front of it?


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## bakewelder (Mar 4, 2021)

zgrav said:


> The audio sample posted above sounds pretty tame to me, but it could be affected by the incoming signal.  What kind of guitar are you using?    Have you tried it with another pedal in front of it?


the video is pretty true to what I hear. That is with the gain cranked all the way up. I tested with a Epiphone SG initially. The audio heard in the video is a Ditto looper playing into the circuit (gain at noon). Did try cranking that signal as well, not much difference. 

For a one knob fuzz, i would expect the clipping to vastly more prevalent. 

My probe broke yesterday, so i will socket up the 1N4148s and give it another go tonight or tomorrow. 

THANKS ALL, appreciate the help. Hope I can count ya when I start in on my Leprechaun that isn't working


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## zgrav (Mar 4, 2021)

if you look at your schematic, this is not a one-knob fuzz.  it is a one-knob volume control.   there is no gain or fuzz adjustment for the pedal except for changing the level of the signal that goes into it.


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## bakewelder (Mar 8, 2021)

zgrav said:


> if you look at your schematic, this is not a one-knob fuzz.  it is a one-knob volume control.   there is no gain or fuzz adjustment for the pedal except for changing the level of the signal that goes into it.


I see. Good distinction. I was just going with the nomenclature I see folk use. Thanks the input


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## bakewelder (Mar 2, 2021)

Preface: Noob here. 

Troubleshooting the Mini-Muffin Fuzz. Passing signal, though only slightly distorted, not fuzz.

After C1, signal drops significantly. Virtually no prob-able audio at inputs of IC (pin 2 or 3). Output of IC at Pin1 is plenty loud, not distorted. Signal at C2 (post diodes and output of IC B)  is distorted but more like slight overdrive, not fuzz. 

Tried a new IC, same results. 

Any suggestions? thanks!


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## bakewelder (Mar 8, 2021)

Update. Put in 1N4148s, and signal is even less clipped (distorted). Grrrrrrr....ready to throw this board in the fire!


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## Chuck D. Bones (Mar 8, 2021)

Have you tried putting another pedal in front of this one so you can drive it harder?  

Which guitar are you using?


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## bakewelder (Mar 9, 2021)

Chuck D. Bones said:


> Have you tried putting another pedal in front of this one so you can drive it harder?
> 
> Which guitar are you using?


Hey Chuck. I am feeding the circuit from a Ditto Looper pedal. Even if I plug my Epiphone SG in, same result.


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## allsmoke (Jan 6, 2022)

I'm going to bump this rather than create a new post.
I just completed this today and it seems both tame and a little scratchy.
I did not have 1N34A so I used BAT41 instead. I have a ton of 1N4148, but read they could not be subbed.
I'm going to clean the board with naptha, and reflow the joints to try clean up the scratching, but will the 1N4148 help give it a little more grunt?

Thanks all


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