LMNC Bandpass Filter

Hey!! Anyone out there build this?

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Well, now I’m about to :stuck_out_tongue_winking_eye:

Let me know how you make out. Been having an issue getting the resonance pot to do anything. Cool sounding filter though!

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Well, I built it and my resonance pot doesn’t do anything either :confused:. The sound also is very distorted pretty much no matter what, so I’m thinking something else might be wrong. Bad chip? I’ll keep plugging…

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Interesting. I’ve built 3. Resonance doesn’t work on any. I get distortion if pots are maxed out, but not so much if backed off a bit. The filter actually sounds great. Really nasally.
I’d just love to get control of the reso a bit.
Keep me posted. Sam said he’d look into the resonance when he gets a bit if free time.

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Yeah, my IC is fine. I have a feeling something’s wrong in the layout.

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Well, I hope someone can help figure out why it’s not working, because I’m pretty pleased with the panel I made for it. It’s stainless steel from a cut up and sanded dollar store ruler. $1 bought me three panels!

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Here’s a quick demo video

My phone seems to have had some trouble dealing with the bass frequencies, so the distortion isn’t actually as intense as it sounds in moments, but this should give you an idea…

Dollar store thrift is such a big brain thing I’m stealing that. I do it for RPG terrain materials, why not modular stuff?

I know you didnt exactly want that result, but its not un-pleasant!

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Here’s 2 of mine. I also added some vactrols for cv. I’m guessing the distortion is from the resonance being pinned. If we could get that control working, i’m guessing we could dial it back a bit.

Bandpass filter test

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The addition of CV definitely makes it more interesting. I agree that the resonance being pinned is what is creating the distortion.

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Any luck with this ?

Is there a schematic to compare to the stripboard layout?
Where is that from? I don’t see it on LMNC’s site.

Some stripboards are found on the patreon. Sam only started including schematics recently, so i doubt there is one for this.

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FIXED AND UP)DATED I realised I didnt include the sources on this one, its from the cgs30 which is the Roland system 100 model 101 bandpass, its a cool band pass,

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OMG, thank you! I was trying to work it out last night :grinning:

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@lookmumnocomputer, @Doolang: I think I found the remaining piece of the puzzle. Untested, but looking at the CGS schematic, I think this might be it!


image

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Sweet! I’ll give this a try this evening!

I mean, this should be in addition to Sam’s fix.

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Nice investigating Christian! I gave it a try! It made the filter work better overall for sure! The nasty distortion is gone when you crank pots to full. I find now the resonance pot has just a little spot in the middle where it rolls off a bit of top end, but I still don’t find it really controls the resonance. I’ll try to upload a video.