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Nice! Those cacti like very well-drained soil. Wet roots will rot. Mammillaria, the clump just right of center in the top photo, are particularly vulnerable. If you haven't done already, a layer of pea gravel on the bottom and a lot of sand & perlite (or vermiculite) mixed into the soil will...

Varying the drain resistor does more than affect the drain voltage. It also changes the output impedance and linearity. The difference between 15K and 20K may or may not be noticeable. The difference between 15K and 30K will be more pronounced.

Seriously? The best path forward is: 1. Detailed visual inspection under magnification. Verify component values, part numbers & orientation. This is especially important when performing mods because mods increase the number of opportunities for mistakes. Check all solder joints to make sure...

Not everyone has your discerning ear, my friend. If there is variability from build to build, it can be as much subjective as it is objective. I do appreciate the food analogy, though. Reminds me of lemon sorbet... a little squeezed, a little scooped. 😎

I should have posted this earlier.

NO!!! The topic here is the DBA Germanium Filter, not stupid transistor tricks. Take this BS somewhere else please. 😁 Reverse beta is tricky business and there is no way to know what will happen with various transistors used that way in a fuzz circuit other than trying it. Not all Ge...

It affects the shape of the FILTER knob's freq response above 1KHz. There would be a lot less high freq content without C5. Q3 has a very low input impedance and it loads the FILTER network. This is not the typical BMP filter circuit. The plot below shows the the FILTER circuit's freq...

Indeed. We'll need better pix too. Measure and report the voltages on the collectors of the PNP transistors so we can see if the bias is in the ballpark. FYI, cramming parts in that don't fit and melting film caps with the soldering iron is no bueno.

Good question! The input impedance is lower then you might think because the Miller Effect reduces R3's impedance by the gain of Q1. Q1's gain in the is circuit is around 36x, which reduces the input impedance to around 26K. Increasing R3 & R4 to 10M increases the input impedance to around...

Maybe you got lucky. 🤞

Good question! Looks like I failed to mention the need to dial-in the bias. We want Q2-E around 4.75V. 4.5V to 5.0V is fine. Select Q1 and/or adjust R4 as required. Best to start with R4 = 1K, get it as close as you can by selecting Q1, then fine-tune with R4. R4 should be between 680Ω and...

This is not the Troubleshooting Forum. Please read a few posts on the Troubleshooting forum to see how we do things and then post a request for help there. I will tell you that troubleshooting Vero boards has a unique set of problems. In particular, I have seen Vero layouts that run the input...

The Sweep waveform is a hyperbolic sinewave. It looks like this: The breadboard has a trimpot, but the schematic has fixed resistors. R51 & R52 provide the correct voltage to select this waveform. Other waveforms can be used, but this is the best match to the sweep used in the GP8.

A client asked me if I'd ever heard the Roland GP8's phase shifter section. I hadn't, but I found a schematic and breadboarded one. It bears some similarity to the MXR Phase 100 in that it contains both variable and fixed phase shift stages. The Phase 100 uses LDRs and has 10 stages; the GP8...

The Mu Amp does two beneficial things for us, compared to a simple one-transistor amplification stage. 1. More Gain! * 2. Nearly symmetric clipping. * HamishR increased R6 in his Mongrel pedal to moderate the 2nd stage gain.

That workbench is way too clean.

I like it! I think C10K would work better for BASS. BTW, Lectric-FX has already used the name "Mongrel" for a pedal.

There's a Vero layout. ☝️ Cooder designed a board. I don't know if Szukalski or any of the other usual suspects have done so.

Why not just buy low-HFE transistors? They are neither expensive nor hard to find. High-voltage, high current or high freq transistors all have reduced HFE because they are optimized for something other than HFE. 2N2369 is an example of a high-freq transistor. 2N6517 is a high-voltage...

Yep, the CMOS distortion stages are sandwiched between a compressor and expander.