Took me a bit to figure this out. I thought I was being smart with my FV-1 circuit knowing it was only going to be mono. So, I combined R/L Input and R/L Output pins. Turns out if you do that you must mix your inputs and outputs to mono in your patch, too. Otherwise you will get something very nasty sounding out of your beautiful patch. My denseness is your gain!
(https://s22.postimg.cc/yxluiob3h/FV1-_TIP.gif) (https://postimg.cc/image/yxluiob3h/)
Hooking inputs together should not be a problem. Apparently you can get a slight noise reduction by doing this and mixing the inputs together in the code. I forget the theoretical basis for it.
Connecting outputs together directly, whether digital or analog, is generally a bad idea. I wouldn't do it even with the code modified as shown.
You can connect your inputs pin1 and pin 2 together but you should NOT connect the two output pins 27-28 together directly. You can connect them together using a resistor and cap network without causing a problem though.
Thanks guys. I ended up physically breaking the output pins connection on the PCB. Not a big deal - just a couple swipes of an Xacto knife :)
I did see one shcematic where the right output was used for feedback only (in a mono pedal) so maybe I'll solder a wire to that pin and try it out.
A follow-up: I kludged together an output cap and resistor on the right output to mix it with the left output. It worked but was noisy as balls. So, it might be best to buffer each output before mixing them. I'm not going to be doing that for any personal designs but maybe it will be helpful for someone else.
On some of my circuits using both outputs of the FV-1 a simple resistor on each output to a common capacitor works just fine, no noise. have you tried testing each output separately for any noise, is it possible that previously connecting the two outputs directly together may have caused damage to the chip.