ilovefuzz.com

I feel like an idiot. I'm trying to throw together a couple RC filters on vero for a sort of passive fixed filter for my synth. I want them to share a common input and then just have an output for each band. This is just the first LP and HP outs. I'll have two BP in addition.



The problem I'm having is that I'm getting what sounds like a BP of both or just the LP from both of the outs! I've gone over this over and over again and I can't figure out why. The outs are isolated via the cut so there shouldn't be a BP, right?? They were working fine before the common input was added so I'm assuming that's the problem but I don't get why. I have everything breadboard with the common input and that works fine. This seems so utterly simple but I'm just

You're running 100% passive and both inputs are connected, yes?

Ponder the diagram a bit and observe the fact that, if the above statement is true the input is loaded to ground by both circuits, which is why you're getting bandpass effect. If you really want to split 'em up, you'll have to go active enough to slap a buffer on (the input side of) each leg, sorry.

Hmm. That makes perfect sense. But I have it working on a breadboard...that's what I'm really confused about. One input feeding all of them and I have one out for LP, one for HP, and 2 BP and each out sounds different.

Got it working with some help from Muffs. I stupidly didn't cut the trace in the middle of the first resistor and cap, thus shorting them out. Whoops.

Cheers to an easy fix!

Now I obviously kinda just want to make it active. But this is just way easier. Ugh.

All it will do is improve the differences and make whatever loading on the output less of an issue - that may or may not be an improvement sonically, depending on needs and taste. Clearly not a requirement in this case (I'm guessing the synth has a low Z output, so loading is minimized).

Yeah, that's what I figured, especially since these are just fixed filters. Nothing too complex needed.