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.
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🙏
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.
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.
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.
@@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.
Your demo song actually elicited some emotions in me (besides the standard "that sounds cool" excitement). That's an exceedingly rare thing. Great stuff.
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.
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 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
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.
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!
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
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.
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.
@@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
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'.
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.
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
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.
@@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.
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.
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!
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.
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.
Recommend a followup video to explain "Bias Current & Trickery" section more thoroughly. Thanks in advance for removing any of the "trickery" from that part.
For this diode ladder filter block, does it require using film caps? I followed along and built this up exactly but I used ceramic caps in place of the 1nf film caps. The square wave signal was dull and had a loud, deep hum. Perhaps the result of using ceramic caps?
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.
New sub! That's the clearest explanation of a ladder filter I've ever heard. I finally get it now. Thank you! Also, I noticed your homebrew synth seems familiar... perhaps similar to another synth in the Kosmos? 😁
@@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.
*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. *
Great video. One suggestion, I think "signal" or "wine wave" or "waveform" is a much more commonly used term than "oscillation". I could see that confusing beginners
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).
Nice deep tech too. pls bandcamp :) BTW do you think it's possible to use LM324 instead of TL072? Because I can't get the TL rn. Or what about NE5532, it's supposed to be low noise but they all are BJT I think, I don't know how BJT effects the signal compared to FET. I might try this out, hope the lower BJT input impedance doesn't spoil everything.
I'd go for the 5532. the LM324's are best suited for single supply operations, if I'm remembering correctly. Something about the output stage creates some distortion when using dual supply (+12 and -12). The RC4558 would be an alternative also
A really cool project for you to do could be to build a frequency analyzer from scratch, using an aux as an input for music or any sounds, it would be awesome
I implemented this one and my filtered signal seems to have some ripples going through it, at random spots, in every peak. I think this was the hardest circuit to build so far.
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..
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 👍
I think a zener would be fine, but the three diodes add up to 1.8V, give or take. Also, when using the zener you should connect it "backwards" when comparing with the 3 diode implementation
@@jorgeguimaraes8820 Oh yes of course. It's 1,8V not 3.6. I understand a zener has to be put in the other way around. It was just a theoretical question really :) Thanks for the reply!
@@EdEditz no problem! By the way, the zener put like this would do the same as the diode string if you think just about positive voltages... Since the CV can go negative, the zener will limit the negative excursion to -0.7V (-Vd), so maybe it won't work exactly like the diodes. Normal diodes clip at 0.7V (Vd) when positively biased (the 3string would clip between 1.8-2.1v) but don't clip with negative bias. The zener clips at Vz (the zener rating voltage) with negative bias and Vd with positive (just like the normal diodes). So, to allow for negative CVs (say, CVs between -2v and +2v) you should use two 2v0 zeners "face to face" (the cathodes in the "middle").
When describing why filter stages should be an odd number, I had a thought: namely, if you were to "tune" the stages properly in an even # diode ladder, could you use this as a basic waveshaper from square to "ramp" ish, with either option of output giving you an up slope or a down slope?
Looks very similar to the Steiner-Parker filter but instead of a differential pair you're using two voltage sources (op amps) and two resistors to set the bias current. Am I right?
There is totally some modulation in that sequence at about 35:00. So added the co and resonance modulation from sequencer or is that filter circuit automatically doing that by design somehow?
Will natürlich auch n fettes Danke! hier lassen für den geilen Kurs. Ich bin seit nem Jahr dabei mir Grundlagen drauf zu schaffen und hab endlich gut erklärt was warum wie, anstatt einfach Schaltpläne aus dem Netz nach zu bauen. mega geil! Aber eigentlich wollt ich vor allem sagen: nice Pflanzenwahl :D Vor allem die ganzen Avocados. Aaber was ist das auf der Sounddemo unten rechts für'n Blatt? Synth&plantlover Grüße aus Hamborch.
Perhaps I'm simply stupid. I recreated, made pcb in altium, built and run many of them but I still don't understand them completly. Vco's are much simplier, especially those built without opamps. Perhaps analyse of whole tb303 filter sometime?
At 29:00 minutes, you have three diodes to protect against the bias voltage going too positive. Shouldn't you have another three, to protect against it going too negative?
in theory, each pair of added stages should make the roll-off steeper (1 stage is 6 db/oct -> 3 stages is 12 db/oct -> 5 stages is 18 db/oct... etc). in practice, this is not going to be so clear cut since the stages are not buffered and therefore influence each other. so i think you get heavily diminishing returns by adding more and more stages. haven't tried it with more than 5 though.
here's a quick version i slapped together. by increasing the capacitance we can actually make the diodes light up! this might look really cool! tinyurl.com/y9e7wxsq
Moritz Klein way cool! I think I left a reply already but it dissapeared? Anyway, gonna try and build this version :) But what’s up with the 5.2V in turning into 2.1V? Should I go with that? I’ll have to figure something out to bring 5.2 down if that’s the case as it’s that and 12 that he have powering our rack.
@@theclovercross yeah the youtube filter will eat comments if they have links i think? sometimes also seemingly at random. weird. with the 5.2V you mean the fact that the CV is much stronger in the LED version? this is actually necessary because one LED behaves roughly like 3 regular diodes - so they need a lot more voltage to start conducting.
@@MoritzKlein0 the schematics were the other way around though. I mean the power coming in in the bottom left part. 12V, -12V and 5.2V in the original and 12V, -12V and 2.1V in the LED one
This filter is so GODDAMN F.CKN' 303!!! Unfortunately I was late this year but I will pose like an idiot with this filter on march 3rd next year :D I must put a classic early 90's smiley sticker on the module.
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.
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🙏
That was probably the most technical video yet but definitely the most musically useful device you have created yet.
I hope you are saving all of your wonderful illustrations. They would make a fantastic book.
Reminds me of Forrest Mims' circuit diagrams
@Baylie ϟymms me too!
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.
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.
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.
@@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.
Your demo song actually elicited some emotions in me (besides the standard "that sounds cool" excitement). That's an exceedingly rare thing. Great stuff.
Excellent explanation and I really like the emphasis on the motivation rather than just describing the circuit.
Your explanation of the circuit design is excellent.
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.
Schematics pls jojo
@@finonomastropiero4261 Demo and a schematic from when I made it -> ua-cam.com/video/Z4o3QnJdoys/v-deo.html
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
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.
love to read what you come up with! also - amazing channel name!
@@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
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!
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.
This is crazy cool, THANK you for making high quality detailed videos like this.
Awesome acid jam ❤❤❤
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!
Great tune. Would love a longer version
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
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.
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.
@@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
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'.
We've all been waiting for this! Thanks.
"oscillation salad" what a wonderful term!
Just did my homework and watched this again before the upcoming premier.. this sounds so good, I must have one!
You’re my favorite UA-camr after this!
Just wanted to say your channel is amazing.
Good to see your channel grow up. Great video as allways! Have a nice day mr. Moritz
I love your presentations and learning unthincable new in my analog knowledge and experience. Thanks!
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!!
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.
Less than a minute into your video and I've subscribed. I'm going to enjoy this channel!
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
Awesome, my first Synthesizer was a Korg Poly800.
There must be snow on your head, caused by your coolnes =)
Can`t wait for more, Mr. Klein!
Beste Wishes
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.
This sounds like something Burial would make. Good work man, learning so much from your videos.
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.
Hey man I think I’m gonna build a pedal for my bass around this using an expression pedal for control. Super neat stuff
Love your channel...
So now I need a comparison of various capacitors in a SEM state variable filter please!!!!!!
Thank you! You have great teaching skills. Can you make a video about OTAs and their use in MS-20 filter type?
Loving all your videos, really helpful in understanding signal flow and how everything works, appreciate your sharing of knowledge dude!
Awesome acid jam❤
Unrelated to the topic, but I like the way you drew all the "S" characters. Great video!
Half S, half lightning bolt
I like it
That Demo was on point.
This was a really, really great video and explanation. Thank you for making these!!
This is wonderfully explained Moritz, thank you. Subscribed
Super series, Moritz! But I will suggest making a 0V reference line, so it gets a little more clear, how the waves are behaving.
you mean on the offset oscillations diagram?
@@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.
@@Qhotex yeah true, in hindsight that would've been clearer.
Thank you so much for making these! Such fantastic help!
once again great great great video!
Awesome presentation and impeccable english! Thanks for posting :)
lovely filter!
yet another excellent tutorial. Thank you.
Looking forward to the follow-up
been waiting for this one!
Next step could be the differential configuration with transistors as diodes like in TB-303.
aphex twin would love that one, very clean sound
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.
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!
This is a great explanation! Thank you!
very good !! 水拉!!!
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.
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.
this would make it much more complicated to get the resonance amp's gain right unfortunately!
Thank you. Informative and easy to understand .
Fantastic videos!
Recommend a followup video to explain "Bias Current & Trickery" section more thoroughly. Thanks in advance for removing any of the "trickery" from that part.
awesome. i wonder if you ever might do a video about a diy spring reverb? (or just a verb in general lol)
it’s on my list!
Would love to see you producing some music with all the tools you're creating :)
The machine is the art at that depth. Why make a finite pattern when can make a machine that makes any pattern?
For this diode ladder filter block, does it require using film caps? I followed along and built this up exactly but I used ceramic caps in place of the 1nf film caps. The square wave signal was dull and had a loud, deep hum. Perhaps the result of using ceramic caps?
Very good understandable knowledge. I saw your videos dont have any youtube monetization advertisements, you should activate it via settings
i keep that turned off deliberately, since i got a decent number of people supporting me on patreon.
@@MoritzKlein0 👍
Thanks!
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.
New sub! That's the clearest explanation of a ladder filter I've ever heard. I finally get it now. Thank you! Also, I noticed your homebrew synth seems familiar... perhaps similar to another synth in the Kosmos? 😁
true, the next iteration will hopefully be a bit less derivative!
@@MoritzKlein0 Nothing wrong with standards. I understand Sam published them for people to use them.
Fantastic!
oh my god diodes make sense now
33:44 "watch what happens as I turn it up....the output dies instantly"
output: *_demonic HF screeching_*
really? i don't hear anything - might be too old already
@@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.
@@6alecapristrudel ah gotcha! yeah true, it looks rather alarming!
*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. *
This is cool, but remember that inverting op amps can influence the offset potentiometer's dynamic stability, so add a filter capacitor to it.
Just letting you know the time used to set up the succulents was not wasted 😂
it's only one succulent so the effort there was minimal
Thanks for the reminder to buy some succulents.
Great video. One suggestion, I think "signal" or "wine wave" or "waveform" is a much more commonly used term than "oscillation". I could see that confusing beginners
A korg poly 800? I have my father's old mkii of that synth!
Fantastic video!
wow that sounds good!
Very interesting, thank you.
Very interesting and well explained. Thanks for your effort.
Can you tell me what the 'SHIFT' module is? Are those just shift registers?
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).
Nice deep tech too. pls bandcamp :)
BTW do you think it's possible to use LM324 instead of TL072? Because I can't get the TL rn. Or what about NE5532, it's supposed to be low noise but they all are BJT I think, I don't know how BJT effects the signal compared to FET. I might try this out, hope the lower BJT input impedance doesn't spoil everything.
i think both alternatives should work just fine. haven’t tried it though, so take this with a grain of salt!
I'd go for the 5532. the LM324's are best suited for single supply operations, if I'm remembering correctly. Something about the output stage creates some distortion when using dual supply (+12 and -12). The RC4558 would be an alternative also
A really cool project for you to do could be to build a frequency analyzer from scratch, using an aux as an input for music or any sounds, it would be awesome
I implemented this one and my filtered signal seems to have some ripples going through it, at random spots, in every peak. I think this was the hardest circuit to build so far.
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..
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 👍
yeah it's about the way the feedback is mixed in with the input signal. the MS-20 filter does it the same way!
@ 28:50 Would a 3,6V Zener diode work too in a situation like that?
not educated on zener diodes, so i can't really say, sorry!
I think a zener would be fine, but the three diodes add up to 1.8V, give or take. Also, when using the zener you should connect it "backwards" when comparing with the 3 diode implementation
@@jorgeguimaraes8820 Oh yes of course. It's 1,8V not 3.6. I understand a zener has to be put in the other way around. It was just a theoretical question really :) Thanks for the reply!
@@EdEditz no problem! By the way, the zener put like this would do the same as the diode string if you think just about positive voltages... Since the CV can go negative, the zener will limit the negative excursion to -0.7V (-Vd), so maybe it won't work exactly like the diodes. Normal diodes clip at 0.7V (Vd) when positively biased (the 3string would clip between 1.8-2.1v) but don't clip with negative bias. The zener clips at Vz (the zener rating voltage) with negative bias and Vd with positive (just like the normal diodes). So, to allow for negative CVs (say, CVs between -2v and +2v) you should use two 2v0 zeners "face to face" (the cathodes in the "middle").
When describing why filter stages should be an odd number, I had a thought: namely, if you were to "tune" the stages properly in an even # diode ladder, could you use this as a basic waveshaper from square to "ramp" ish, with either option of output giving you an up slope or a down slope?
Looks very similar to the Steiner-Parker filter but instead of a differential pair you're using two voltage sources (op amps) and two resistors to set the bias current. Am I right?
There is totally some modulation in that sequence at about 35:00. So added the co and resonance modulation from sequencer or is that filter circuit automatically doing that by design somehow?
This video is amazing.
Will natürlich auch n fettes Danke! hier lassen für den geilen Kurs. Ich bin seit nem Jahr dabei mir Grundlagen drauf zu schaffen und hab endlich gut erklärt was warum wie, anstatt einfach Schaltpläne aus dem Netz nach zu bauen. mega geil!
Aber eigentlich wollt ich vor allem sagen: nice Pflanzenwahl :D Vor allem die ganzen Avocados. Aaber was ist das auf der Sounddemo unten rechts für'n Blatt?
Synth&plantlover Grüße aus Hamborch.
There is some diode style reason that a diode clipper such as the MXR makes such a synth sound "best" in some ways?
Perhaps I'm simply stupid. I recreated, made pcb in altium, built and run many of them but I still don't understand them completly. Vco's are much simplier, especially those built without opamps. Perhaps analyse of whole tb303 filter sometime?
At 29:00 minutes, you have three diodes to protect against the bias voltage going too positive. Shouldn't you have another three, to protect against it going too negative?
That red cap is another 1uF foil capacitor with simply a diff color?
thank you!
Are diodes adding signifficant noise?
don't think so, my PSU is just very noisy plus breadboards usually exacerbate the problem
How do the # of stages effect the filter? Is 5 the minimum? Is there a maximum? TIA you're the best!
in theory, each pair of added stages should make the roll-off steeper (1 stage is 6 db/oct -> 3 stages is 12 db/oct -> 5 stages is 18 db/oct... etc).
in practice, this is not going to be so clear cut since the stages are not buffered and therefore influence each other. so i think you get heavily diminishing returns by adding more and more stages. haven't tried it with more than 5 though.
would this work with light emitting diodes?
i think so, but you'd have to boost the CV by a factor of 2-3x since 1 LED behaves roughly like 3 1N4148 diodes! haven't tried this yet though!
here's a quick version i slapped together. by increasing the capacitance we can actually make the diodes light up! this might look really cool! tinyurl.com/y9e7wxsq
Moritz Klein way cool! I think I left a reply already but it dissapeared? Anyway, gonna try and build this version :) But what’s up with the 5.2V in turning into 2.1V? Should I go with that? I’ll have to figure something out to bring 5.2 down if that’s the case as it’s that and 12 that he have powering our rack.
@@theclovercross yeah the youtube filter will eat comments if they have links i think? sometimes also seemingly at random. weird.
with the 5.2V you mean the fact that the CV is much stronger in the LED version? this is actually necessary because one LED behaves roughly like 3 regular diodes - so they need a lot more voltage to start conducting.
@@MoritzKlein0 the schematics were the other way around though. I mean the power coming in in the bottom left part. 12V, -12V and 5.2V in the original and 12V, -12V and 2.1V in the LED one
This filter is so GODDAMN F.CKN' 303!!! Unfortunately I was late this year but I will pose like an idiot with this filter on march 3rd next year :D I must put a classic early 90's smiley sticker on the module.