Dead End Platypus

[digi2t]

Discovered the Way Huge Purple Platypus some weeks back. Wasn't initially impressed, but this has been on the breadboard for a while now, and I'm pretty happy with it now. Added my own tweaks; octave on/off (with LED), octave intensity control, and Mill 2 bypass. I upped the base gain resistor to 68K because I was getting a bit of a step in the gain at the low end of the pot. 68K smoothed that right out. The russian D9V diodes in the octave section are the cat's ass. They offer a vF very close to silicon, but with a very gentle knee of germanium. The higher vF seems to allow chords to sound less ring-modish, while still allowing a fairly decent octave bloom on single notes. The transistors are also the result of lots of trials. They work really well together, but anything similar will work too. Socket and swap is the name of the game. Also upped the filtering, 100uF right at the power, and 470uF for the unused pins, which help tame any possibility of oscillation or poor decay from the 4049.

PCB is on it's way, but here's a schematic and vero for the vero/perf freaks.





Enjoy!

[Mark Hammer]

Neat!  Personally, I've been finding that Schottky diodes in the D2/D3 position are the feline behind I prefer.  I find I can get nice octaving down to, and even below, the 5th fret.  Mind you, this design may allow that already.

The front end is very clearly a Red Llama derivative.  Do you find there is enough output level to cope with any passive loss from an added tone control?

And of course, you just know I'm going to suggest a diode pair plus 1k in parallel with that 100k resistor to ground just before the volume pot.

[digi2t]

Not sure if there's enough push for an added tone control. A recovery section might be required, but only more breadboard noodling will determine that. If I lean on what's going on in the Lion X though, I would say "maybe" yes, recovery section might be required.

I've been on a bit of a Tube Fuzz / Llama run of late, this being number 3 of that iteration (following Schumann's Lion and Lion X). I'm really becoming fond of this circuit. I've found that just varying some cap values around the 4049 get me into a zone where I don't even need a tone section. Just the tone control on the guitar, and the amp's eq being more than plenty to put a smile on my face. The Lion X is really the exception to that rule with it's twin BPF sections adding tons of tone shaping options.

And of course, you just know I'm going to suggest a diode pair plus 1k in parallel with that 100k resistor to ground just before the volume pot.

Yeah, thought about it too, but I thought it might subtract from the overdrive feel. Definitely an option though. It's wide open for experimentation, that's for sure.

[Mark Hammer]

What does that diode/transistor combinaion in the upper right hand corner do?

[Scruffie]

What does that diode/transistor combinaion in the upper right hand corner do?

Looks a bit millennium bypassy to me.

[digi2t]

What does that diode/transistor combinaion in the upper right hand corner do?

Looks a bit millennium bypassy to me.

Upper right on the schematic, lower right on the vero. Correct.

[Mark Hammer]

Looks a bit millennium bypassy to me.

You're probably right.  I overlooked the little slashes indicating an LED and thought it was "just" a diode.