pricklyrobot
Active member
…well, okay only one finished Muff at the moment. Second coming soon.
I’ve had a GGG Op-Amp Muff kit sitting around forever, and a BYOC NYC Muff kit (guess it’ll be my last BYOC build
) only slightly less long. Finished the Op-Amp on Saturday. Features a Crested Caracara, pretty common site around Austin and south of here, but very rare to see one outside of TX. Very cool raptor/scavenger. Read all about ‘em!
Crested Caracara Overview, All About Birds, Cornell Lab of Ornithology
The Crested Caracara looks like a hawk with its sharp beak and talons, behaves like a vulture, and is technically a large tropical black-and-white falcon. It is instantly recognizable standing tall on long yellow-orange legs with a sharp black cap set against a white neck and yellow-orange face...
www.allaboutbirds.org
The mods are adding a Tone Bypass switch to the GGG, and making the High a Low-pass cutoff frequencies adjustable on both:
I spent quite a while plugging values into here http://www.muzique.com/schem/filter.htm until I arrived at something that seemed like a useful range. Gave the high-pass a wider range, so it could overlap the low-pass range and get a band-pass response:
Then it was time to figure out what pot tapers would give me a useable sweep:
The verdict
If I was going to do it again, I’d pick a different PCB (sans off-board wiring) and/or use a bigger enclosure, so I wouldn’t have to use 9mm pots and have a spaghetti mess of wiring. But I wanted to use up stuff I already had, and I made it work in the end
Re: mods
The Tone Bypass is definitely noticeable, and useful. The adjustable filters are a little more subtle, I’ll have to play with them some more. Kinda wish I had a stock Muff to do a side-by-side comparison. It was an easy mod though, just swapping two cap values and changing two resistors to pots. Doing the calculations to try and figure out right values for everything was a good learning experience if nothing else!
* I’ll add Muff #2 in this thread, whenever it’s done…
