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No. The clipping diodes are clipping at voltages that surround vref by 0.6v (depending on choice of diode). Vref is not relevant to the clipping symmetry. Asymetrical clipping would be by using two different diodes (or multiple diodes in series) to create the asymettry.

Could also save a component and do this...

And, the sour grape has a vref supply and then doesn't use it as the reference to the first op amp???

The sour grape has a vref buffer and doesn't use it! The output of this opamp is a perfect Vref supply to the rest of the circuit. And the resistor divider could be bumped up to 1M and only need a 0.1uf filter cap on it since the op amp will draw only a couple hundred pico-amps. That said, it's...

Show me a schematic...

It could be used to buffer the bias voltage, too.

Online calculator for current in a trace... https://www.advancedpcb.com/en-us/tools/trace-width-calculator/ Nothing on a guitar pedal is going to force you to larger traces. Even power delivery is low current but I use as big as will fit for power. If you need high current in a trace, like in a...

And a reminder to folks new to this thread... These need a good preamp to make a pedal board amp. I have PCBs to do this and I suggest using the volume-only version. And, they can also have an XLR installed, presuming you are using a cab-sim ahead of this power amp. My build guide for various...

Those are selling for 99 cents right now at Ali to new subscribers. Hint, hint, to folks who want some... And only 2 bucks for for those of us who've bought from Ali before. I just ordered 10 because... How can anyone skip this? And I'm insane... The TPA3118 chip from mouser, for 10 of them, is...

A real one in one of my pedal builds for comparison. 32-pin IC. Discrete components all the same. Fakes have a 28-pin IC and discretes are moved. In particular, C20 in the lower left is R20 on a fake. And a fake. Note R20 and pin count. And no C20 to be found.

Those look exactly like my real ones.

And this is the microscope. https://www.amazon.com/gp/product/B09VPPS96M?psc=1 But, I rarely pull that off the shelf now. I have one of these cheapos on a goose neck permanently on my bench. The included little table and mount is useless. Need a much bigger goose neck to hold it up higher out...

I don't use a stencil. Smear paste on the pads, sparingly, and it wicks right onto the pads nicely in the heat. (Only suitable for boards with a solder mask, of course.) This worked really well making 10 TPA3118 boards all at once and all 10 were perfect. And works for the J177 and 2SK208R in my...

Oh, and the choice of 1M or 10K depends on the load that will be put on the bias voltage supply. For jfet input op amps, the input current is very low and 1M ohm is fine and won't drain a battery. But, if you are running from a non-battery power source and have other circuits drawing from that...

This is likely because the op amps used don't have a symmetrical common mode voltage allowed at the inputs. Here's the spec range for a TL072. This means the input voltages for op amp function are from 1.5V above the negative (ground in your case) but can go all the way up to Vcc. So, the ideal...

I use a hot plate to do all the SMT stuff at once. Solder paste on the pads with a toothpick. Stick the parts to the paste. Put the board on the hot plate until the solder all flows. Done. I made some videos of doing this with a TPA3118 board. The solder wicks onto the pads nicely on the hot...

Thanks. I have a laser machine for graphics. So, it only does one color etched to raw aluminum, but I like that aesthetic. I have a BOM in excel format at PCBWay for each. When you order, you will need to specify what parts to install or not.

By the way, if I was going to order them assembled again, I would entirely leave out the drive channel (and pots, LED and LED resistor). Then I would have a small pile I could turn into anything version.

Yes you can order them assembled but they don't seem to have a source for the alpha pots. I've ordered some built and it's not a bad deal but I left out of things that I would need to tweak and install myself.

Yes. This PCB can implement a full AMT pedal in a 125B case if that is what you want. It cannot do the high gain versions, like S2, P2. But, the more gain stages, the more these pedals sound trashy/thrashy. I love the E2 and M2. The O2 is lower gain but really sounds good and is over-drive-pedal...