#8: Post by luma » October 19th, 2016, 8:31 am

zachig wrote: WOW!!! Nice job!

zachig wrote: I'm wondering...is this software capable of detecting only 1st crack? Or also 2nd?

zachig wrote: In case a more sensitive USB Microphone (Condenser?) will be used (rather than the cheap one you used), will it improve the detection?

Thanks! Just realized I never responded to the posts here so here goes.The training process is pretty general purpose, and in limited experiments I was able to train it to recognize things like the drum motor and the fans (not always doing so on purpose mind you.) Presumably it would also work to detect second crack. As I basically never roast to that point, collecting data on 2nd crack would require throwing a bunch of beans away which I've been reluctant to do.Funny story about that: I've been helped out on occasion by the nice folks at Ferris coffee. For this project I approached them with a weird request: do you have any absolutely awful greens that you'd sell for cheap which I can roast to a crisp and record with a microphone so I can test some machine learning etc etc? I must have sounded like a nutter, but they obliged and dug up 20# of horrible Robusta for very little money. I took it home and fired up my HotTop to learn a few things. First, sh**ty Robusta beans are small and tend to fall directly through the holes in the drum pretty readily, leaving me with an overflowing chaff tray and a drum whose holes are stuffed full of charred black beans. Second, Robusta makes nearly no noise at all during second crack, certainly not enough to pick up a clear signal over the machine sounds.Can I interest anyone in 19# of some quality Robusta?Maybe? The USB mic is a condenser just because they are cheap and (generally) offer a flat response curve and high sensitivity. I wanted to avoid anything too exotic with hopes that others could replicate the results without spending a bunch of money on esoteric recording equipment. As it happens I do have a calibrated measurement mic and a reasonable pre-amp, but haven't bothered deploying that as I'm not terribly convinced it's going to improve things much. If I wanted a warm, natural sound then I could see spending $$$ on a nice dynamic mic, but for a flat response curve and high sensitivity condensers are just the ticket. It just so happens that they are also cheap