Designing a diode ladder filter from scratch

[@codyjohnson5954]

I hope you are saving all of your wonderful illustrations. They would make a fantastic book.

[@cadikaorade828]

Reminds me of Forrest Mims' circuit diagrams

[@jacobsteel]

@Baylie ϟymms me too!

[@infiniteoffset]

Honestly I'm not even building diode ladder or anything related to synths, but I love watching your videos, because of how well the videos are made. Good job!

[@rockpadstudios]

yeah - very cool vid's

[@boonedockjourneyman7979]

I’m a traditional old fart. I’ve seen waves of creativity go by over 4 decades of professional life. You are going to be a star. The technology, the art, the dynamic art of the lights, and not least of all, the music, will take you far. I can visualize a Rammstein album cover, music video and melody based on your work. You should do some demos. And yes old guys listen to them. Metallica paved a path for us old guys years ago.

[@onpatrolforthejuice]

I love this series so much. I've been an analog repair tech and tester for a circuit company for years now but these videos have helped me grasp some fundamental understanding which I had been lacking all this time.

[@OMNI_INFINITY]

*Wow...ONE BREADBOARD???!!! I wasn't expecting that. Seems somebody is German (or maybe Austrian, but that's not so different). Planning to make that. Thanks!*

[@WibblyWobblyBob]

Thank you for making this series. I have learned more from 2 evenings watching your videos than 40 years of fiddling with electronics. Your plumbing analogy is brilliant. I look forward to seeing many more tuturials from you.

[@juppster5694]

Excellent presentation! I am an electronics engineer, and I love the way you come at your explanations: e.g. the changing resistances of the diodes with current, in the resonator amplifier feedback circuit, and how the stage-gain is reduced at higher amplitudes by 'straightening out the exponential curve'. Very detailed discussion - most (including me!) would have just said 'diode clamp' and not considered the detail! Very helpful for those of us who think we know it all already 😆 Thank you🙏

[@warpigs330]

These videos are really helping to open the doors of analog electronics. I have been wanting to make a filter, and experiment with weird, maybe counterintuitive topologies, but didn't know where to start. The difference between the positive offset and negative offset, plus the placement of the resonance, there is a lot to tune there. I would be really interested in how to turn this into an all pass filter, I have been wanting to get some of those phaser sounds.

[@MoritzKlein0]

yeah that's why i decided to go with this instead of another OTA-based approach. much more room for creative tweaking! (also LM13700s are expensive.) i'll do a follow up on converting this into other filter types. eventually i'd also like to do a PCB layout when i feel the featureset is refined enough.

[@warpigs330]

@@MoritzKlein0 the fact that this design doesn't use any fancy components means I will likely be able to design a pcb to be assembled by JLCPCB, and have them do most of the components.

[@dentakuweb]

That was probably the most technical video yet but definitely the most musically useful device you have created yet.

[@scrapeape]

Your demo song actually elicited some emotions in me (besides the standard "that sounds cool" excitement). That's an exceedingly rare thing. Great stuff.

[@rolandtriton]

Iam a mechanical engineer by major, the way you explained electronics made huge sense, I wish we had this 20 years ago, thanks for the good content

[@sams_sekai]

Waking up to this on my birthday was a very good thing! Awesome explanation as usual!

[@MoritzKlein0]

happy birthday!

[@kaloyankrastev638]

This filter works really well. The other day one opamp on mine apparently failed. It's cool how these analog devices can sound nice even with a major damage. The sound was similar to warm distortion on a guitar. I suspect the reason for the failure Is that I modified the CV input and might be causing it to go way high on voltage on the ladder. Thank you for your work again!

[@256byteram]

That sounds great! Simple design too. I did one ages ago by taking a state-variable filter and replacing the two cutoff frequency resistors with boring old diode bridges, and basically doing the same positive/negative control voltage you've done across them. Worked really well too, plus you get low/band/high-pass out of it.

[@finonomastropiero4261]

Schematics pls jojo

[@256byteram]

@@finonomastropiero4261 Demo and a schematic from when I made it -> kzbin.info/www/bejne/kGXSZISkf8mir9U

[@fermiLiquidDrinker]

I already have a decent amount of experience with VCFs, but I still learned something from this video! Your design is honestly brilliant-it's like a further simplified Steiner-Parker filter; your filter doesn't use a differential ladder, so it'll be much more stable with regards to temperature. I'll probably try my hand at a mathematical analysis of this filter soon.

[@MoritzKlein0]

love to read what you come up with! also - amazing channel name!

[@fermiLiquidDrinker]

@@MoritzKlein0 I'm busy on the Arp 4072 filter as of the moment, so it might be a bit before I getting to your filter. I'll let you know when I start on yours

[@FahlmanCascade]

Your explanation of the circuit design is excellent.

[@andrewlecouteurbisson7217]

Excellent explanation and I really like the emphasis on the motivation rather than just describing the circuit.

[@mathewthomas3238]

I breadboarded this today and it sounds absolutely awesome. I want to build a euro module but I'm afraid your next version is going to be even better!

[@OMNI_INFINITY]

Any breadboard layout schematics? Been trying to decipher what is in the video onto a breadboard style layout. Thanks in advance, if can post a reliable diagram of that.

[@22222Sandman22222]

Wow, I've never seen better explanations for synth electronics. These definitely help me fixing some quirks in my DIY modular! Thank you so much!!

[@why_do_you_care]

Being an electronics engineer, I can say that such sound and simple explanations for analog circuit design are tough to find. The logical flow and simple language helps one to be a 'part of the design process'.

[@iamsushi1056]

"oscillation salad" what a wonderful term!

[@OscarUnderdog]

This is crazy cool, THANK you for making high quality detailed videos like this.

[@novictim]

Awesome acid jam ❤❤❤

[@cadra400]

You, sir, are a fantastic teacher. Please keep making these videos. I hope you'll one day do a similar breakdown/comparison of other filter types, like the Moog transistor ladder, or late MS-20 OTA type.

[@MoritzKlein0]

transistor ladder is next on my list!

[@johnsaunders6510]

A lovely sounding filter.

[@TediumGenius]

I've come late to the game and your series here, but as a fan of ELP, Kraftwerk, and synths, I am absolutely fascinated! Your explanations are PRICELESS!!!!!! I am a hobby musician and have some electronics background, as well as a new scope I want to get to know, and your videos are PERFECT as a companion!! Very very well done, very consistent videos, and wow, I can't say enough good!!!

[@DarioMoog]

Thank you! You have great teaching skills. Can you make a video about OTAs and their use in MS-20 filter type?

[@JagerMagic]

Awesome, my first Synthesizer was a Korg Poly800.

[@julian4035]

Earlyer I know nothing of this now i know always! You are so good

[@agiantalienforce]

Great tune. Would love a longer version

[@devjock]

I'm fascinated by the fact that so far, there hasn't been a single sighting of expensive transconductance amplifiers. I'm sure they'll be used in the future, but it's nice to know there's a lot of good control possible with bog-standard opamps. Well done man. This series is truly inspiring.

[@MoraFermi]

1. The "transconductance" op-amps would be needed if the filter's steering element was a BJT. 2. "Transconductance" amps are essentially amps pushing a set amount of current through the load... 3. ... which means you can do it with a "normal" op amp and some fancy feedback loop, if you don't mind part count explosion. 4. Internally they're current mirrors, so replacing them with discrete transistor pairs/trios would probably work too, for that old-school, wobbly sound.

[@devjock]

@@MoraFermi Oh I'm aware OTA's are usually used in combination with a bjt, just loved the fact that there's a feeling of it being slowly worked towards. Parts explosion is fine in that case, because it facilitates the style of the video. More parts means less multi-function parts, means easier to wrap the mind around. Don't get me wrong, I do be liking the wobblies too, but I have a feeling this series is working towards more accurate modules later-on. Ideal diodes (Jim Patchel) in place of the split "dual"-filter elements would be a nice way to get the filter's "around 0v" area more linear (as well as it being a nice intro to waveshaping/folding). tldr; Yes :D

[@OMNI_INFINITY]

Part of what makes it nice is the synesthesia with that scope. Without the scope visuals in synch I'm thankfully generally over that sound.

[@jakesnell7707]

You’re my favorite KZbinr after this!

[@wuukaa9079]

So much work in this video! Can't wait for the high pass filter!

[@interference7480]

Just did my homework and watched this again before the upcoming premier.. this sounds so good, I must have one!

[@Asdayasman]

4:14 このディオです！ The more polite Dio, after jumping out of the bushes and saying "boo" to surprise Erina on April Fool's.

[@punman5392]

Hey man I think I’m gonna build a pedal for my bass around this using an expression pedal for control. Super neat stuff

[@ProjektNordpol]

There must be snow on your head, caused by your coolnes =) Can`t wait for more, Mr. Klein! Beste Wishes

[@PeterWalkerHP16c]

We've all been waiting for this! Thanks.

[@soulrobotics]

For being an excellent musician your are an excellent electronic guy!!. Hats!

[@rpa231]

Just wanted to say your channel is amazing.

[@davec8385]

These videos are incredible. You do a fantastic job of teaching how these ideas work in a simple to understand way. I hope you have a great rest of your day

[@37leonardo]

I love your presentations and learning unthincable new in my analog knowledge and experience. Thanks!

[@skriptico]

Yessir!

[@davidvallejo9184]

I liked the moving representation of the circuit on the simulations page, I always wonder how it flows, now it is clearer to me, you are the best!!

[@jmannUSMC]

This will go down as the most approachable German engineering to ever exist 🤘

[@scottlarson1548]

I had no idea diodes could do so many things. Transistors get all the glory.

[@MandelscapeDA]

Love your channel... So now I need a comparison of various capacitors in a SEM state variable filter please!!!!!!

[@nsomer2718]

I built a nano-amp scale ammeter using a 1N4148 diode. It works great! I use it in high voltage work to measure very small currents

[@DollysplitBand]

Jeez man that kick sounds absolutely lush.

[@diglet553]

Just discovered your channel and I love it! You've reawoken the DIY synth spirit within me 😁 Also, loved the sequence, sounds almost 303 like but not. That's the cool thing about diode ladder filters; they sound rubbery and acidic.

[@josseman]

This is the first video I saw of you. Your talent is marvellous! Both good at explaining electronics and making music. Awesome! Greeting from the Netherlands

[@christophschuermann7920]

Hi Moritz, thanks for another great video! First off all: I would buy your drawings in an art gallery if they were signed by you :-). If you plan to build a stable and good "pro-version" in series, please consider the use of diode-arrays in one case. This allows good traking and temperature behavior and some are available in DIL or SIL-cases for easy prototyping. Cheers from Kaulsdorf, Christoph

[@MoritzKlein0]

great idea, thanks for the suggestion! i'm planning to do a proper PCB & panel once i've added at least a high-pass (and maybe a band-pass) option, so i'll probably use such an array then!

[@ivand8393]

Would you please comment the temperature dependency of the filter, because as you know most diodes have a negative temperature coefficient (about −2 mV/oC for silicon diodes). And the room temperature can be probably in range 15 oC to 30 oC and even more during the global worming ;-)

[@MoritzKlein0]

yeah ambient temperature will have an effect on the cutoff frequency. but afaik most filter designs don't compensate for this (unless you want to play it as a stable v/oct oscillator) because the effect shouldn't be that dramatic.

[@nicholasroos3627]

@@MoritzKlein0 I wonder how much affect it will have as it is the junction temp. Maybe less than expected based off the change in ambient T? Hmm.

[@MoritzKlein0]

@@nicholasroos3627 i'll try breathing vigorously onto my breadboard

[@slick8086]

Great Video.... now where is that dang bag of diodes!!

[@MoritzKlein0]

50-pole filter, let's go!

[@ichadc]

Unrelated to the topic, but I like the way you drew all the "S" characters. Great video!

[@wesleymays1931]

Half S, half lightning bolt I like it

[@neail5466]

I was searching for this kind of analogue electronics explanations all over the internet.. you really granted my wish. I hope you will cover more in future. Thank you very much.♥️+1

[@codehorror8076]

This sounds like something Burial would make. Good work man, learning so much from your videos.

[@novictim]

Awesome acid jam❤

[@OMNI_INFINITY]

I made some iOS apps with a VCS3 filter emulation and taming that filter from going straight to full peak was a process. I may cover the ear that has some tinnitus when testing that filter on a breadboard. It’s like the sound of something flying up into the sky and then suddenly vanishing from this simulation

[@Qhotex]

Super series, Moritz! But I will suggest making a 0V reference line, so it gets a little more clear, how the waves are behaving.

[@MoritzKlein0]

you mean on the offset oscillations diagram?

[@Qhotex]

​@@MoritzKlein0 Yes, and the Odd/Even diagram as well. Thank you for this series. Really motivates me to do electronics, after a long period only programming.

[@MoritzKlein0]

@@Qhotex yeah true, in hindsight that would've been clearer.

[@JAPANLOVESTAR]

*URGENT!: I need to pack (including the electronics assembly area) to go to another country and I need to get that filter functioning properly before I do! I finished building it on a protoboard (with similar layout to a breadboard, although an extra rail on top and bottom and some on sides), but it’s still not functioning yet. Sigh. That was as much work as building a small building with the right tools seemingly. And I know a building would actually function properly. Sadly the filter hasn’t functioned at all yet seemingly. There was a high pitch sound from some points on the board when had the dual supply a little low. Sadly no potentiometer has done anything to make it output sound from what is seemingly the output yet either. Was SOOOOOOO MUCH WORK. Sigh…* I have REALLY learned that I should ALWAYS have PCB made when making any electronics circuit that isn’t as simple as most guitar pedals. And then also prefer to have a proper PCB. Anyway, here are the photos. Maybe there is something obvious simple and easy issue on it that will be easy to solve. The dual power supply is at maybe 11.87V. Note: Swapped the ground and other rail on the side with the row of caps. Didn’t install the audio ports yet, simply using wires straight to speaker and a 555 synth. Disregard the other circuit on left of the breadboard, as that is a multistable vibrator that isn’t connected. Thanks in advance for advising SOON on how to make it start functioning! Tested continuity all over the place, although didn’t go through maniacally methodically to confirm all continuity at every single point in that circuit. Underside has no bridged columns and that is a breadboard style stripboard. So it’s laid out based on the final breadboard schematic in that erika synths manual for that filter. (version 2.0 of that manual) Photos are on imgur. Sadly youtube was deleting any comments with imgur links, so change the [dot] to a ".", obviously: imgur [dot] com/a/KFrPShY*

[@wedkarzkosma]

Good to see your channel grow up. Great video as allways! Have a nice day mr. Moritz

[@TimSavage-drummer]

Less than a minute into your video and I've subscribed. I'm going to enjoy this channel!

[@-prajna-9545]

very good !! 水拉!!!

[@akabomb]

The best video explaining the diode filter I've seen so far! The style of your videos is very charming and it helped me learn a lot. Thank you! My choice is pretty limited in terms of getting photoresistors too, so this filter would be a nice option.

[@stephenyoung8960]

Keep these videos coming please :)

[@sgrimm7346]

Excuse the language, but this is Fking genius! To the others that also understand engineering, you know what I mean......Carry on please. I just had to drop my 2 cents.

[@desmotsdesfaits5795]

once again great great great video!

[@6alecapristrudel]

33:44 "watch what happens as I turn it up....the output dies instantly" output: *_demonic HF screeching_*

[@MoritzKlein0]

really? i don't hear anything - might be too old already

[@6alecapristrudel]

​@@MoritzKlein0 Nah, the audio went quiet, but the waveform on the scope became a solid bar. Like a high frequency oscillation seen with a slow timebase.

[@MoritzKlein0]

@@6alecapristrudel ah gotcha! yeah true, it looks rather alarming!

[@jimmygervaisnet]

Sounds great! I just don't understand where the CV input comes in...

[@MoritzKlein0]

check 28:36

[@jimmygervaisnet]

@@MoritzKlein0 oh! I thought that was the sound input lol thanks

[@dgp1498]

lovely filter!

[@FilipMilerX]

Next step could be the differential configuration with transistors as diodes like in TB-303.

[@crazyirishman121]

That Demo was on point.

[@flaminggarlic]

I added voltage control to the resonance with a simple Santana JFET VCA, and added a non inverting summing stage to combine the CV and Resonance pot voltage, with clipping diodes to constrain the voltage to a range between roughly 0V and 5V. I had to flip the resonance input amp to an inverting configuration since the VCA is inverting the signal, and I didn't do the actual math to change the gain, I just guessed, but it seems to be pretty similar resonance. Here's a link to the falstad circuit: tinyurl.com/yz9nl6fo

[@MoritzKlein0]

looks good!

[@alexwood020589]

I really like the technique, it's not something I've come across before, and I can't wait to try it out! At 26:11, I'd have given the non inverting stage the gain and made the inverter unity gain. That way, you're not amplifying the noise from the first stage with the second.

[@MoritzKlein0]

this would make it much more complicated to get the resonance amp's gain right unfortunately!

[@hlw8051]

Very clear appreciate the content

[@BUCKSINSIX69]

Moritz, you are my new hero. WOW... just wow

[@LaurentLaborde]

why nobody ever explained this to me before ? "the increase in current will be exponential" "you can think of it as a voltage controlled resistor". it make it so easy to understand... wtf ?!

[@ciro_costa]

i thought you'd end up having some noise problems because of the amplification but it turned out fine! amazing video as always!! if that wasn't the case i'd suggest zener diodes the ones rated to 3.6V would require a lesser reduction of volume (if i got the workings of the circuit right) so you'd have a greater separation between the signal and the noise floor during the amplification stage.

[@MoritzKlein0]

might be a good idea to try this since the output stage definitely is susceptible to picking up noise. you can keep it to a minimum by using proper decoupling & keeping the big gain op amp as close to the PSU as possible though!

[@SkunkBunk]

This is awesome! Thanks for being so thorough in your analysis.

[@makarocket]

this is an awesome demo on how a diode filter works!! thank you!!

[@iswimwithsharks]

Loving all your videos, really helpful in understanding signal flow and how everything works, appreciate your sharing of knowledge dude!

[@OMNI_INFINITY]

Recommend a followup video to explain "Bias Current & Trickery" section more thoroughly. Thanks in advance for removing any of the "trickery" from that part.

[@samcarswell9890]

This was a really, really great video and explanation. Thank you for making these!!

[@soejrd24978]

Looking forward to the follow-up

[@TPItsMe]

Just letting you know the time used to set up the succulents was not wasted 😂

[@MoritzKlein0]

it's only one succulent so the effort there was minimal

[@tillorrly1128]

Thanks for the reminder to buy some succulents.

[@tourtravel2624]

Very good understandable knowledge. I saw your videos dont have any youtube monetization advertisements, you should activate it via settings

[@MoritzKlein0]

i keep that turned off deliberately, since i got a decent number of people supporting me on patreon.

[@tourtravel2624]

@@MoritzKlein0 👍

[@ghlscitel6714]

I think I never needed a Diode Ladder Filter. But it sounds interesting. However I built quite a few diode capacitor ladder high voltage power supplies.

[@tuff_lover]

aphex twin would love that one, very clean sound

[@fruitpowerofeden-2022]

yet another excellent tutorial. Thank you.

[@joelkulesha8284]

Thank you so much for making these! Such fantastic help!

[@OMNI_INFINITY]

*There is a lot of hidden filter modulation to make that quack like that? Seemed to be a surprisingly large jump at a certain point in that video. I've built an emulation of that before and seems as though it didn't sound like that before adding envelopes to the filter. *

[@r51f20]

Hi from Russia! You make great content, please create video about your rack modules from 3:20. I'm started to build my own rack and cant choose what I want in it.

[@MoritzKlein0]

you mean like a tour?

[@r51f20]

​@@MoritzKlein0 Yes, I think an in-depth tour would be helpful to understand what you are using.

[@obscurer1898]

awesome. i wonder if you ever might do a video about a diy spring reverb? (or just a verb in general lol)

[@MoritzKlein0]

it’s on my list!

[@magiceireann]

This is wonderfully explained Moritz, thank you. Subscribed

[@JenkemFactory]

I'm very surprised the resonance sounds so good and squelchy when the feedback isn't inverted! It's my experience that positive feedback should have the opposite effect and make the filter sound really woofy.. if that scetch is correct I must be missing something..

[@JenkemFactory]

I think i got it, is this due to the capacitor and diodes behaving like a highpass filter for the feedback? Still amazed of how good and tight it sounds, great low-end retention at high resonance 👍

[@MoritzKlein0]

yeah it's about the way the feedback is mixed in with the input signal. the MS-20 filter does it the same way!

[@tedvanmatje]

Awesome presentation and impeccable english! Thanks for posting :)

[@joelandersson3474]

Would love to see you producing some music with all the tools you're creating :)

[@OMNI_INFINITY]

The machine is the art at that depth. Why make a finite pattern when can make a machine that makes any pattern?

[@carneeki]

A korg poly 800? I have my father's old mkii of that synth!

[@Axelvad]

Thanks!