ms20 Jorg schmitz layout

isak · Posted: Wed Jan 02, 2013 2:24 am Post subject: ms20 Jorg schmitz layout

i was wandering if you guys can help me with something please.
from the next layout..
http://www.analog-synth.de/synths/mod2/ms20filter/rene_ms20_filter_clone%20rev%204.pdf

build it and i'm not sure about the sound, i dont have an ms20, never had one, so i really dont know if its came out ok.

i attached the sound demos for you to hear, can you please tell if its sounds like yours?

used -/+15V
green leds.
Saw wave from the Odyssey VCO (Andy1960 layout).
first demo - reso is at 12 o'clock.
second demo - reso is at 3 o'clock
third demo - reso is all the way up.

please tell me if the reso is ok and its sound like the original.

i thank you in advance.
cheers,
Isak E.

12 oclock reso.wav

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3 oclock reso.wav

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reso all the way up.wav

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LektroiD · Posted: Thu Jan 03, 2013 7:58 am Post subject:

I can't help with the sound comparison (although going by memory, it sounds very familiar). I would however, be interested to know if it's easy to adapt this into the elusive MS20 HPF?

isak · Posted: Thu Jan 03, 2013 8:18 am Post subject:

Very easily.

Lock at the first link I uploaded.
Now, you see the 1nF blow the upper 3080?
Take the right pin of this cap out and connect the sound source (vco) to that pin, that's it, you got HP Smile

cheers.

LektroiD · Posted: Thu Jan 03, 2013 3:48 pm Post subject:

Simple enough to make it switchable then... I'm now wondering if there's a bandpass (or notch) on the board to tap into...

isak · Posted: Thu Jan 03, 2013 10:11 pm Post subject:

here you go...
http://www.birthofasynth.com/Scott_Stites/Pages/dualms20_main.html

LektroiD · Posted: Fri Jan 04, 2013 2:33 am Post subject:

isak · Posted: Fri Jan 04, 2013 4:20 am Post subject:

The .47uF is poly, no polarity.
I put 100k to all,like the original scheme says, didn't check it tho..
before going further with this project I want to make sure the sound I get is correct.
please pay attantion to the next post..(roll down a bit)
http://electro-music.com/forum/post-375902.html#375902
important info Sebo is giving me there Smile

isak · Posted: Fri Jan 04, 2013 8:19 am Post subject:

BTW...
More important note.
When on LP mode right pin of 1nF need to be connected.
When on HP right pin of 1nF need to be disconnected and act as the input.
So you will need a 6 pin on & on switch.
One operation to move from LP to HP, second operation to connect and disconnect right pin of 1nF.

steffensen · Joined: Jul 11, 2012 Posts: 103 Location: Sweden

I too can only judge from memory, and i do hear the MS-20 vibe goin on here. Good work my friend! Sounds awesome.

isak · Posted: Wed Jan 09, 2013 4:28 am Post subject:

Thanks

I made a dual ms20.
After seeing the next vid I'm sure the Jorg design is close to the original Smile

move to 2:00 min Wink

http://www.youtube.com/watch?v=6o6XCj5LjOo&sns=em

If you guys have more refferensece I'll be happy to hear.

Cheers.

LektroiD · Posted: Thu Jan 10, 2013 5:40 pm Post subject:

I built it, initially wiring up the power backwards, but since replaced the 2x CA3080's and the TL074, and it doesn't work... It seems to make a bandpass effect when I wire the in to the out and vice versa, but in the normal configuration I get nothing except a small amount of random noise...

What else might have popped?

isak · Posted: Fri Jan 11, 2013 1:54 am Post subject:

Try to check all the jumpers.
I did a mistake with 2 jumpers when soldering them.
Oriontetion of the IC's.
transistors i used is BC557, dont know what you used but check the pinout.

LektroiD · Posted: Fri Jan 11, 2013 4:08 am Post subject:

isak · Posted: Fri Jan 11, 2013 5:42 am Post subject:

Can you upload the full pcb size pic?
If I recall the 470nF at the output needs to be poly.
did checked the led oriontetion?

LektroiD · Posted: Fri Jan 11, 2013 10:01 am Post subject:

The updated photo... I didn't fit the LED's as I thought these were only for display, not functionality...

*Edit*
LED's fitted, makes no difference, except they display when the source is plugged into the output (nothing happens on the input)

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isak · Posted: Fri Jan 11, 2013 11:30 am Post subject:

LEDs need to be green, it's important.
Don't plugin nothing to the input, first let's check if it's working right.
the LEDs need to be off (not lighted) when the reso is all the way down CCW.
Is it like that?
If yes turn the F to 12 o'clock and slowly trund the reso CW the LEDs need to light after half way (12 o'clock) and fully lighted when turning the reso all the way.
In this way it suppose to self osc.
Please try that and report back.

LektroiD · Posted: Fri Jan 11, 2013 5:03 pm Post subject:

Green LEDs are in, but I can't do any more tests for two weeks, as I'm away. They only lit when a source was plugged into the output. I'm wondering if I popped the transistors too when I fed it with inverted power...

mrkva · Posted: Sun Apr 06, 2014 3:34 pm Post subject:

Hey guys,

maybe you can help me out. I've built myself the same circuit.
Filter part is working without issues, but resonance acts weird. It get very resonant around 1 o'clock and higher, and only in high frequencies. Maybe like just 3-5kHz. LEDs are lightning up in high resonances. I used same values as in the circuit, except the frequency pot which is not 47k but 100k - shouldn't matter right?

Thanks for any help/info