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The 2SK209 datasheet does not show a thru-hole device, only SMD. The 2SKxxx thru-hole devices I'm familiar with all have the gate on the middle pin. I see what you did there with the switch. Not sure it's necessary, but it does no harm.

Another OD inspired by HamishR down under in Perth. His earlier versions had four JFETs and a different tone stack. I took one of the later versions, deleted a source-follower stage between the clipping diodes and FMV tone stack, fiddled with the EQ and clipping a bit and here's where I ended...

My maternal grandmother was born and raised in New Brunswick.

Imagine what it's like living south of the border. Hooray for Canada's New Citizenship Act Bill C-3.

Tariffs are not about protecting American businesses. They are about market manipulation.

Here's the Luna Fuzz mod. Ref des match the GPCB Build Docs. Some part numbers / values changed, a few parts deleted. Compare the two schematics to see what I did. Watch the pinout when installing Q3.

I think it will but you should try it and see for yourself. The point of the anti-pop resistor(s) is to ensure that all of the caps are charged to the same DC voltage before they are switched into the circuit. That means that Ca & Cb each need a resistor.

By choosing the correct caps, you get the same effect. Whether you parallel 2 caps or 3 to get 4+uF, it doesn't matter. The electrons don't care. I'll spell it out for you: C5 = 470nF Ca = 1.5uF Cb = 3.3uF C5 + Ca = 1.97uF C5 + Cb = 3.77uF that should be plenty close. If it's not, then use...

Ya beat me to it! It will pop when switching. To cure that put a 1M resistor from pin 1 to 2 on the toggle switch and another from pin 2 to 3. I recommend film or tantalum caps.

Indeed. It was a ticking time bomb that might never have gone off. Or it could have killed me while hiking over an 11,000 foot pass in the Sierras.

Yup. About a year ago to fix an Anomalous Origin of the Right Coronary Artery. Had it all my life without knowing it because everything was working ok. They spotted it on a CT scan when they were looking for something else. Fixing it was a preventative measure.

Since we're sharing scars...

Not good, should be equal to Vref. Oh, now I see it. You have pins 2 & 3 swapped on U1. It's a wonder any sound comes thru at all. TONE & LEVEL are also wired backwards. This you first board layout project?

You have Q1-Q4 D & G swapped in your measurements. The DMM is slightly loading the measurements at Q1-G, Q2-G & Q7-B, but we can correct for that. Looks like there is flux reside on the board. If so, clean that off. Your schematic has Q5 E&C swapped. Same for Q6. The datasheet is 100%...

OK guys, please take it somewhere else. Start a new thread in General Questions. You can link to discussions here, but I'm try to keep the thread short and to the point.

Are the readings for the JFETs D-S-G? Are the readings for the BJTs E-B-C? Complete information is good. Q1-S & Q3-S are connected together. Why are their voltages different? Same goes for Q2 & Q4. Q5-C and Q3-G should be the same voltage because Q3's gate current is essentially zero. 3...

Why do I feel like this discussion has drifted from the topic of how passive filters work to design mods for the Chickenhead?

3.9M should be close enough.

I wouldn't expect all of the resistor values to be the same if Q3 is changed to Germanium, but I've been wrong before. Check the collector to base voltage on Q2 because it will be much lower than if Q3 is Si.

IMHO, transistor sockets in pedals is no bueno. It's a potential reliability problem. If you must use sockets to select transistors, which BTW is not necessary with the Aldrin, then after selecting transistors, either remove the sockets or solder the transistors into the sockets.