I tried out some 5mm red LEDs in place of the 1n34a's a few minutes ago. The octave effect was more pronounced with the 1n34a diodes than it was with the red LEDs, but the LEDs sounded a bit punchier, and a bit brighter, whereas the 1n34a's seemed a little bit dark to me.
To summarize in a few words:
1n34a = more pronounced/crazy octave effect, but a tiny bit dark.
1n4148= most pronounced octave, and has an almost Fender Blenderish sound to it. The octave is definitely the craziest here.
5mm red LEDs = less pronounced octave, a bit brighter though, and sort of crunchy (almost like turning the Llama into a distortion with an octave effect)
Again, that's just my opinion. Someone else could here these things completely different from me, but that was my take on the three sets. If anyone else wants me to try swapping some parts out, this stuff will stay on my breadboard for another hour or two, but then I'm starting a new project.
