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Jacob and Angelo, you're probably right. I think it's partly in everyone's nature to look at the word "goop" and cry foul, but I did very much appreciate that it was a thing I could hold onto, toss around, and put on a shelf without worrying about damage.

I came up with a great use for these -- as the division switch on a taptation! It can do four of the five settings with the right wiring (I drop the dotted 16ths). I'll have a build posted in the next few weeks using it.

If you want to run the Cardinal in parallel with something, you pretty much just have to add a non-inverting buffer after the volume pot. But there are probably better implementations if it's going in an amp ... PM me if you want more specific thoughts. Mostly it involves removing the "amp simulation" aspects of the Cardinal.

Wow, that's almost enough to make me go to SMD ...

I wonder how close they are chip to chip, though?

What about that circuit is patentable?

Well, you CAN patent implementation (see: Mesa Boogie). That doesn't mean it's a robust patent that will stand up to challenge. Thus, the goop.

Interesting tidbit: Once again, goop was used to hide something that wasn't exactly original. People still would have used the bricks if they'd known what was in there ... the things are super convenient.

Happy 5th Anniversary to MBP. Brian, thanks so much for building such a wonderful community. These all sound like ambitious, but certainly achievable, goals.

a little off topic, but could I use a trim pot in place of a resistor on a board. I have read that I could just use the middle and one ends as a lead. I only ask because I have to Bias some j201's for some other builds that I have been putting off. If this would work I could build the circuit and then use the trim pot to find the resistor I need.

Yes, of course. But most builds with FETs use trimpots unless the biasing isn't critical.

First off GREAT demos, I looked these PCBs up on YouTube.  I am getting ready to place an order and wondering if a 20k Trimmer would be okay in place of the 25k trimmers the Thor and Azabache are asking for?

"Most likely."

FETs are like delicate little snowflakes, and the biasing can be precise in Runoff Groove builds. However, there is a bell curve to the expected drain values required to properly bias the FETs. Runoff Groove's design philosophy indicates that one should use a trim pot twice the size of the expected value when building with FETzer valves. If you're building with a J201, you can expect the drain value to be a touch over 10K -- which means a 20K will actually get pretty close right in the dead center, but some super incredible outlier could require a larger trim pot. In other words, 20K is just fine for the Azabache for sure, but I thought you'd like to know the why of it.

I can't speak regarding the Thor, I haven't built that one, only breadboarded it. Marshalls just aren't my thing.

Wow!

2. Forget No. 1 when someone makes a layout with adjustable decay.

Even better, assuming that the brick is not super-hard to open up, any parameters should be able to be controlled externally. So you could have the best of both worlds.

Or add Pin 7 LEDs! No more distorted bricks!

The Kingslayer is approved for small quantities of commercial builds.

The Multiplex, however, is not. Paging Josh ...

Thanks! I'm still learning about this stuff and I'm sort of "building-by-numbers." So, if I understand correctly, the diode is like a faucet on a sink; a lower Fv means that the voltage "flows" less restricted, right?

That's an okay analogy, but better suited to resistance.

http://en.wikipedia.org/wiki/Diode#Semiconductor_diodes

In general, you want to use diodes with the same forward voltage when substituting. Datasheets for diodes can be hard to interpret, though, which does make it hard. Some suppliers will just tell you the Fv.

Any Schottky diode should be an okay sub for the 1n5817, including 1N60P, BAT41/43, etc.

Weird that Mammoth doesn't carry those, they're extremely common. Even Tayda has them.

As far as "significantly altering the sound" you have to determine what the diode is doing in the circuit.

In the Fatpants, the Schottky diodes are part of the charge pump and you can think of them as essentially directing the DC. Higher Fv will cause greater voltage loss. Ideally, you'd use the lowest possible forward voltage you can get out of a semiconductor, but I don't really know if there's anything that goes lower  on average than the .2V of the 1N581x series.

d'awww.

We used to have a cockateil. I love birds, especially smart ones. Can't really have birds and cats, though.

The doppelganger clip sounds lovely, but I wonder how much you were clipping the preamp in the last three clips -- looks very smashed and there's some harshness.