Just to clarify -- I first built IVIark's layout EXACTLY to Dumbloid spec including the correct opamp and pot values. Tried it out, then decided to try a few different opamps for fun . . . and I liked the MC33172N as johnk recommended -- it just sounded a bit more like a saturated amp to me (slightly less fuzzy decay). It's a very miniscule change but I could hear a slight difference and preferred it over the original chip. Again, a very minor
change. The nice thing about a DIY project? No goop so I can try different components if I wish.
Then I realized I didn't like the TONE or VOLUME pots -- with the switch on ROCK, the tone got very bright after 9:00 on the dial and the 'sweet spot' (for me, at least) was very small. That's typical of linear pot here -- I didn't like it and prefer the more gradual sweep of an audio pot . . . it's just easier to adjust. Same for the volume -- with the 100K pot it goes into boost after about 9:00 on my rig -- I prefer a more gradual volume increase. Neither of these 'mods' change the sound, they only allow for better adjustability.
I'll stand by my 'not worth the fuss' comment. It's a nice circuit, I get the whole Dumble thing, it sounds pretty good . . . but it's not worth the $300 to me, let alone $600. And if anyone bought one of the $999 double versions on eBay, I'd have to ask . . . . how high was the tree you fell out of? Did it hurt landing on your head? And I trust my own ears, too -- been playing since 1970, gone through tons of gear, yada yada.
But I also realize that I'm looking at this from the perspective of a DIY guy -- it's much easier for me to experiement with circuits and such than someone who doesn't know which end is the business end of a soldering iron. As such, I don't get real excited about ODs or fuzz pedals or whathaveyou and can be a bit jaded at times . . . but if you're happy with your purchase, no need to keep coming back and reiterating -- we fuckin' get it aleady.
(Don't feel bad, I pretty much had the same reaction when I built a Jan Ray . . . )