TUTORIAL Double Entendre Fuzz - Double Muff

BuddytheReow

Breadboard Baker
This is a great circuit and hits close to home for me. I stumbled upon this demo of it. It's essentially a double overdrive/fuzz pedal. Is it a muff? Well, IMO not really, but it sure sounds pretty good.

Anyways, if you're interested in this one here is the build doc. https://www.pedalpcb.com/docs/DoubleEntendre-PedalPCB.pdf
The full schematic isn't very monitor friendly to post here, but it's in the build doc and I'll put snippets here.

First up, the power section
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3 electrolytic caps and 2 1K resistors. We're going to need both sides of a breadboard for this one so let's split them. The top left cap in the pic is c100 and comes right from power input. Then it branches out into 2 separate 1k resistors. Jumper those into the two power rails and connect the other 2 caps to ground. Note that I fixed the top cap in the pic to go to ground after I finished this build, but you get the idea....

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Alright. Let's start out signal input.
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R1 and C1,R2 run parallel to each other. Together, they slow down the signal and act as a passive tone filer. The input is my orange jumper wire in the pic. You can see that the 22k resistor and C1,R2 start and end in the same rows. I added a small white jumper to move on to the next section. There is a 2.2m resistor to ground (reduces switch pop and adds impedance). Then a 220n is next with a 100k resistor to ground.
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Looking at the schematic, you will notice that their are 2 transistor sections that run parallel to each other. I'm trying to limit my pics that I can post, but believe me it's there. What happens in this circuit is that the signal goes from the section we just wired up through the transistors to output. There is also a switch at the end of the circuit which allows you to select whether you want the first set only or both circuit blocks.

That being said, let's start working on the second circuit block as well. A 10k resitor into a 220n cap with a pulldown 100k resistor (goes to ground). You'll then need a jumper to attach c3 and r8 in the first circuit block. I chose to make them go "backwards" and you'll see why in a moment.

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Ok. Now the transistors. Don't let this photo intimidate you. The bottom portion is a mirror of the top with ONE exception. I will explain the top portion only and point out the only change in the bottom. You'll need bc550b's here. I've added the red jumper wire to allow the signal to go into the base of Q1. There is a 100k resistor from power into the collector (left pin), a jumper from emitter (right pin of Q1) to ground, and another jumper from the collector of Q1 into the base of Q2.

For Q2, there is a 10k resistor from power into the collector and a 3.3k resistor from emitter to ground. Also, take you 1u electrolytic cap with the positive end into the collector and the negative goes into the next section (diodes).

Here's the difference between the two circuit blocks. In the top section there is a jumper wire going from the emitter of Q1 into the c3/r8 combo that travels "backwards". I made the layout this way to allow room for the transistor sections. Now, in the bottom section there is merely a 100k resistor that goes from the emitter of Q2 into the base of Q1. In the below pic you can see that I put it right before the red jumper wire. You can do either here.

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Ok. Now, the diodes and volume pots. This should be pretty easy. I added a small jumper out of the 1u caps to give me some more room, but you don't have to here. Then install a pair of diodes going in opposite ways to ground. I used 1n4148s like in the build doc. In the same row put in a jumper wire going to your 100k pots (lug 3). Lug 1 goes to ground (you can put them anywhere on the rails) and lug 2 goes into the switch which I'll cover next.

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Ok. The last piece of the puzzle here. I'll post my breadboard pic, but I don't think it won't help too much so I'll explain here since not everyone has my handy little dpdt mod board.
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Using a spdt switch, pin 2 of the top circuit's pot goes to lug 1 of the switch. Pin 2 is your output.

For the bottom circuit, you'll need to add a jumper wire from the lug 1 row of your breadboard ALLLLLL the way back to the input of the second circuit block. That's the 10k resistor into the 220n cap. Then at the end of the bottom circuit, pin 2 of the pot goes into lug 3 of the spdt switch.

And there you have it!!!!!

Now here's my 2 cents on this circuit. Yes, there are 2 volume pots, but one of them really isn't necessary. I tend to dime my volume pots unless it's a booster circuit or REALLY loud like the El Sol distortion. With the switch engaging the top section only the pot acts as a pure volume pot. Engaging the bottom section allows tweakability using the top sections pot to dial back the hard clipping you hear. What I'm trying to say is the top section is overdrive and the bottom section is borderline distortion which is pretty cool if you ask me.

Happy New Year, y'all!!!!

BuddytheReow
 

fig

Village Idiot
Your tutorials are presented so that anyone can build and better understand these circuits. I look forward to the next one!
 

BuddytheReow

Breadboard Baker
MODS

Right out of the gate I would change the diode combos to see what you like best.

I also want to play around with the input caps since the overall tone is a little on the thin side. I'm thinking C1 is the culprit here, but when I have time I'll tweak this to taste.

Since this is in the Muff family (a distant cousin, perhaps?) I put in a BMP/recovery tone control and really liked it. I have the "standard" tone stack on stripboard, but would like to play around with the mids a bit. I will circle back with my findings here.
 

BuddytheReow

Breadboard Baker
So, the mod that I did was take out C1 altogether and the sound got much warmer and fuller to my ears so I kept it out. R2 isn't connected to anything at this point so I removed it as well. I also added a Pedal Block tone control (BMP) and an LPB-1 as recovery.

I liked this circuit so much I whipped out some stripboard and a soldering iron to make it more permanent. More to come in the Build Reports section....

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