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Late MS20 HP & LP VCF by Réne Schmitz (2nd MS20 filter) - DIY Modular in a Week 7.4
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- เผยแพร่เมื่อ 4 ส.ค. 2024
- One of the most DIY made Voltage Controlled Filters must be the MS20 filter. But did you know there are two different kinds of filters that was put in the MS20, depending on how old it is. In this second episode I make the OTA version of the filter, also known as the "late" MS20 filter as dubbed by Réne Schmitz whose design I am using today. This filter is more extreme than the last MS20 filter type especially in the resonance.
I made a few modifications in this build aswell.
First I used a LM13700 instead of the two CA3080 used in the original schematics. I also added a high pass filter input by adding a 1nF capacitor and a jack between O2 and A2 as Réne suggests.
I also added female headers where the two diodes should be, as Réne also suggests that other diodes could work. So experimentation is prepared ;)
Day 7: Filters
Part 4: 2nd/"late" MS20 filter by Réne Schmitz
Difficulty: Intermediate
Price: ~10$
MiaW playlist: • Modular In A Week (MIAW)
Visit my Patreon page for more (different) content, or if you just want to support my work more than just a thumbs up :)
/ sourceryone
Link to the schematics:
www.schmitzbits.de/ms20.html
Link to the frontpanel design:
www.dropbox.com/s/a44zbztcey1...
Link to oscilloscope:
rover.ebay.com/rover/1/711-53...
Tim Stinchcombes extensive write up on the MS10 and MS20 filters:
www.timstinchcombe.co.uk/index...
Great filter...inspiring series..well done!
Dude, finally wrapped this thing up and played with the rest of the system. OMG, I lost myself in synth-world, forgetting to make dinner for the fam. So freakin' amazing. And yes, LOUD! I just couldn't stop twisting and turning things in and out of this! Ok, on to -dun dun- the Moog filter! And once done with the Moog and Sythrotec I'll do a filter day/week/month jam to show y'all. Thanks for everything!!!
Ola
Kristian. É um prazer enorme participar do seu canal, tem me ajudado bastante nos projetos. Saudações do Brasil.
I literally just finished a PCB I was etching from Look Mum's design, so it's only a low pass. Time for some bodges to get that HPF action!
It is quite an easy addition. Make sure to add a breaking jack that connects to ground when nothing is plugged in. As per Rénes instructions
Hi all, please be adviced that this filter do get loud from time to time, so if you wear headphones, have them at low volume...
I really like this series.
MiaW2: rhythm? ;)
Definetely, rhythm, clocks, dividers, and sequencing, oh and drums :)
bella idea!
i guess it is pretty randomly asking but do anyone know a good place to watch newly released series online ?
@Briggs Nixon i watch on flixzone. Just search on google for it :)
Hi. When looking at the schematics, do I take for granted that what I see IS with the revision 2 and 3 or do I have to modify this schematics by applying the revisions. Thanks!
Hi kristian! First of all thank you for the knowledge you share with us in your videos! I wanted to ask you a question. I built the filter but it has a low resonance, I dont know why cause I used all the component values listed. How can I change the resonance maximum amount? Changing a resistor or maybe skipping it? Thank you so much in advance.
Did you use the value pot as is in the schematics? do you maybe have a low signal in? Otherwise I guess a smaller value resistor in the feedback loop could work?
@ thank you for the reply kristian I had a little short that made the filter loose Resonance. Now it sounds how it should! Keep up the good work mate!
Hi christian, Everything is working fine as I told you unless that the filter doesnt filter all the audio signal. When I close the filter I still can hear some of the higer frequencies that have been cut, but much more quieter. Then in a matter of 2 or 3 seconds those frequencies lower their volume and cant hear them until I open and close the filter again. Its like theres some super low DB signal skipping the filter than in some seconds disappear. I know its pretty hard to know what could be the problem with the filter just by this explanation, but I thought you could have an Idea where I should start to look. Thank you so much in advance!
Hello,
Congratulations and thanks for your hard work.
I'd like to share a question with you.
I build this filter following lmnc schematic, and works, let's say pretty well, but my doubt comes when it starts to self oscillate,mine stars when resonance pot is half way let's say 5\10 and starts screaming, I don't know if it is normal or not, because I don't know the original filter's behavior.
When the resonance is completely closed 0\10, then there is no sound, don't matter how much I opened the cut off.
Is all that a 'regular behaviour'?
Thanks again
I know I'm a year late, and I hope you've figured it out by now! But no, that's not how its supposed to function. One issue you may be having is that your input waveform isn't large enough. I had this issue, and increasing the Vpp (voltage peak-to-peak aka how large the waveform is) fixed it right away
One more question - so you mention testing other transistors vs the (green) led's. Any results from that? What did you end up going with? Thanks!!
I stuck with the green less. :)
*leds
@ OK, thanks!
Rene's schematic has a "Pitch In" jack. This doesn't seem to be on your panel. Any idea what it is and what it does?
OK OK, I just scrolled down and saw the comments re this issue. My bad, but in my defence I've been working on the layout most of the evening and I'm at the bottom of a bottle of wine..
Any idea what the "pitch" input is on the left side? I notice it's not on your design and he doesn't say anything special about it. Thanks!
That is just a cv input without the attenuator. Probably though to be used in keyboard or sequencer cv to let the freq of the filter follow the keyboard/sequencer. There of pitch. But technically it is another cv input.
@ Ahh, got it. Yeah, I'll leave it out too. Thanks!
As you're using a LM13700 instead of the ca3080, i guess you should use the buffers the lm13700 offers, and then use a tl072 instead of the tl074, right?
Yes. That would be possible. I think I did it as I did to be more true to the original schematics. :)
@ By the way, did you experiment with various diodes/LED ?
I did but I don’t remember my findings. 😅
Hi Kristian! I build MS20 LPF clone LM13700 version (Rene Schmitz project), but it doesn't work (ok, it's work unstable). Signal from my VCO (square) lost on pin 12 LM13700, where it sounds like: th-cam.com/video/rzDJ4xWRdE4/w-d-xo.html. I don't have oscilloscope. Sorry for my english. Greetings!
That could be a feedback loop. Try turning resonance down.
It's not resonance. Yesterday I solved problem. I had connected wires between ICs V- pins and next I connected pin from one of this ICs (TL047) to supply voltage. Similarly I had with V+ pins. I disconnected this and connected supply pins to supply voltage independent. I removed decoupling caps also (2x 100nf) - but I have other decoupling caps except that.
Great that you fixed it. It’s an awesome filter! :)