# Designing a diode ladder filter from scratch **URL:** \ **Category:** Videoos\ **Created:** [March 9, 2021, 7:55pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118 "2021-03-09T19:55:57Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 9, 2021, 7:55pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/1 "2021-03-09T19:55:57Z")
hi people, here’s the latest episode in my filter design series. this time, we’re building a three pole diode ladder filter (though it could be debated if that is indeed the right name … ah semantics). it has nice smooth resonance and is very stable (unlike some other diode-based implementations)! let me know if you have any questions & thanks for watching! [![](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/3/3f2369e61b90bc13defac36f50c09b6d26076d68.jpeg "Designing a diode ladder filter from scratch") ](https://www.youtube.com/watch?v=jvNNgUl3al0) ---
**Author:** ![lookmumnocomputer](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/lookmumnocomputer/32/23_2.png) [@lookmumnocomputer](https://lookmumnocomputer.discourse.group/u/lookmumnocomputer)\ **Post date:** [March 9, 2021, 8:34pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/2 "2021-03-09T20:34:37Z")
whey hey Moritz! niceeee. ---
**Author:** ![CTorp](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/ctorp/32/15023_2.png) [@CTorp](https://lookmumnocomputer.discourse.group/u/CTorp)\ **Post date:** [March 9, 2021, 9:29pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/3 "2021-03-09T21:29:18Z")
Watched this morning! Loving the series! ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [March 9, 2021, 10:21pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/4 "2021-03-09T22:21:35Z")
Really thank you for sharing this ! I post it also in the thread with the others one 😉 > [@DIY Synth (electronic video for beginners) - Moritz Klein](https://lookmumnocomputer.discourse.group/t/diy-synth-electronic-video-for-beginners-moritz-klein/1312/24): > > Designing a diode ladder filter from scratch [https://www.youtube.com/watch?v=jvNNgUl3al0&t=312s](https://www.youtube.com/watch?v=jvNNgUl3al0&t=312s) also in this [thread](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118) ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [March 9, 2021, 11:04pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/5 "2021-03-09T23:04:58Z")
Have you a complet schematic for this filter please ? I often take screenshots but it would be easier 🙂 ---
**Author:** ![saint\_et\_moudulard](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/saint_et_moudulard/32/12683_2.png) [@saint\_et\_moudulard](https://lookmumnocomputer.discourse.group/u/saint_et_moudulard)\ **Post date:** [March 10, 2021, 1:45am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/6 "2021-03-10T01:45:16Z")
@moritzklein thank you a lot for your great work sharing, this is very helpfull for all the diyer community! I LOVE your tutorials, better serie than Netflix !! I advise everyone to support him on his patreon page, nice surprises await you !! Im studing your diode ladder filter version, and it look nice!! Recently, I have build a 9v version of an diode ladder filter by Tom Gamble which looks pretty much like this one, but with multiple cv and audio inputs !! I like it so ! (I suppose it can be working with 12v too) Here the schematic: ![Screenshot_2021-01-11-04-01-56](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/6/6de77181d739b28245e5b271d123ec56c4d03e0e.png) Source: [http://synthdiy.fonitronik.de/index.php/efm-files](http://synthdiy.fonitronik.de/index.php/efm-files) I want to build a other version with a Q cv control (resonance), it look very usefull ! (take a look of VCF-6C by EFM) My build: ![16153406475462028627619](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/4/4cd0f2bf5b1230d4ccefee8cc2908cf4853b41d9.jpeg) ---
**Author:** ![CTorp](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/ctorp/32/15023_2.png) [@CTorp](https://lookmumnocomputer.discourse.group/u/CTorp)\ **Post date:** [March 10, 2021, 2:01am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/7 "2021-03-10T02:01:28Z")
@moritzklein I have to ask about your “shifts” module. Honestly I don’t even care what it does I just want that LED rainfall 🤣 ---
**Author:** ![Caustic](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/caustic/32/15588_2.png) [@Caustic](https://lookmumnocomputer.discourse.group/u/Caustic)\ **Post date:** [March 10, 2021, 2:53am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/8 "2021-03-10T02:53:54Z")
Nice video as always! Makes me wish i didnt sell my korg poly-800 years ago though! ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 10, 2021, 6:45am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/9 "2021-03-10T06:45:12Z")
unfortunately i can’t really draw it by hand (doesn’t really fit on one page). but here’s a complete simulation on falstad: [https://tinyurl.com/y7eftwyz](https://tinyurl.com/y7eftwyz) also, here’s how you would mod it to get a resonant bandpass: [https://tinyurl.com/y95z6k4m](https://tinyurl.com/y95z6k4m) ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 10, 2021, 6:51am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/10 "2021-03-10T06:51:17Z")
mine feels like it’s on its last leg unfortunately – LFO starts modulating things randomly and spontaneously, headphone output has loud ground noise… sad! ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 10, 2021, 6:57am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/11 "2021-03-10T06:57:25Z")
it’s basically just 10 4-bit shift registers chained together. i then selected three LEDs where i attached basic gate-to-trigger converters. so the idea is that you can send in bits (either manually via a pushbutton or through an external input) and have those circulate through the registers. every time a bit passes a gate-to-trigger converter it fires. so something like a sample & hold for rhythm! you can also choose if you want it to loop and from where (after the first 4, 8, 12, 16 … bits). ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 10, 2021, 6:59am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/12 "2021-03-10T06:59:07Z")
great looking panel! is that wood? ---
**Author:** ![saint\_et\_moudulard](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/saint_et_moudulard/32/12683_2.png) [@saint\_et\_moudulard](https://lookmumnocomputer.discourse.group/u/saint_et_moudulard)\ **Post date:** [March 10, 2021, 7:07am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/13 "2021-03-10T07:07:09Z")
Thank you, yes it’s recovery wood, I use a lot of old drawer bottoms or cases of strawberries from the market to build my Hobo synth muaha ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 10, 2021, 7:20am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/14 "2021-03-10T07:20:34Z")
hello m’leader, how’s it hanging? ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [March 10, 2021, 12:37pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/15 "2021-03-10T12:37:28Z")
Thanks, i made a copy, invert it and re write the value is it good ? EDIT : deleted a bad version’s schematic ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 10, 2021, 1:28pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/16 "2021-03-10T13:28:01Z")
almost perfect – there is one 22k resistor in there that should be a 33k! also i noticed that for some reason the resonance sounds nicer with a 100k/27k combination instead of the 10k/2k7 in the resonance op amp’s feedback path! ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [March 10, 2021, 1:42pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/17 "2021-03-10T13:42:58Z")
Thx, ah yes i correted it. (and delete the older one in my previous post) like this ? ![diode ladder filter schem](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/b/babe3a0637091afde38e55e68044d90b2daf92cd.jpeg) ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 10, 2021, 2:36pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/18 "2021-03-10T14:36:32Z")
spot on, looks great! ---
**Author:** ![Dud](https://yyz2.discourse-cdn.com/free1/user_avatar/lookmumnocomputer.discourse.group/dud/32/610_2.png) [@Dud](https://lookmumnocomputer.discourse.group/u/Dud)\ **Post date:** [March 10, 2021, 11:55pm UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/19 "2021-03-10T23:55:20Z")
I’ve just made a stripboard layout of it ![diode ladder filter by sound bender](https://global.discourse-cdn.com/free1/uploads/lookmumnocomputer/original/2X/4/4903704a4624f5a7d5fa7064574fe863d2175561.png) ---
**Author:** ![moritzklein](https://avatars.discourse-cdn.com/v4/letter/m/d78d45/32.png) [@moritzklein](https://lookmumnocomputer.discourse.group/u/moritzklein)\ **Post date:** [March 11, 2021, 8:56am UTC](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118/20 "2021-03-11T08:56:19Z")
looks good. proper decoupling & dealt with the unused op amp too! great work! [Next page](https://lookmumnocomputer.discourse.group/t/designing-a-diode-ladder-filter-from-scratch/3118.md?page=2)