MFOS sv-vcf's Built in The Netherlands & Southern Scotland

Skrog Productions

Hello

While in the chat room , i learned that wmonk was building a mfos 12dB/oct. vcf, at the same time as me , yay Smile

.

I've finished my one over the weekend , a couple of silly wiring mistakes fixed now and it's working well , i'll post some mp3's in a few days .

this is the 3rd mfos state variable vcf i've built for the blue wardrobe , this time i used red box polyester 'Wima' caps mostly throughout and i really like the sound , slightly more aggressive sounding than an older one i built with polystyrene caps for C2 & C3.

I modded the audio input section of the board to make an 8 channel mixer (5 extra 1M resistors & 100Nf caps) .

a very handy filter.

Dave.

12dB VCF front panel.JPG

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12dB VCF rear.JPG

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loydb · Joined: Feb 04, 2010 Posts: 393 Location: Providence, RI

Nice! Mmmmm. Bluuuuuuuue.

I look forward to the mp3s!

Skrog Productions · Posted: Sat Oct 16, 2010 7:19 am Post subject:

here's some sounds.....

mfos sv-vcf sweep no res.mp3

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sweep of cutoff with no resonance applied

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mfos sv-vcf sweep no res.mp3

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mfos sv-vcf sweep with res.mp3

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sweep of cutoff with resonance set to 3/4

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mfos sv-vcf sweep with res.mp3

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mfos sv-vcf lfo mod.mp3

Description:

vcf lowpass & bandpass mixed out with sqr lfo on cv2 input , and tri vc-lfo on cv1 input

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mfos sv-vcf lfo mod.mp3

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2.98 MB

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wmonk · Posted: Sat Oct 16, 2010 12:48 pm Post subject:

Sounds great Dave!
I would have expected that you would be way faster then me, hehehe. Still awaiting my order for most of the capacitors. In the meantime, a picture of the panel.
Cheers,
Woody

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Skrog Productions · Posted: Sun Oct 17, 2010 3:37 am Post subject:

Looking great Thomas , good choice having the sockets at the bottom of the panel , easy access to the dials Smile

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How do you fix your pcbs to the panel , do the pots / sockets hold an L bracket or do you bolt through the front panel like i do ???

What caps did you choose for C2 , C3 ? .

id love to hear your filter after completion Very Happy

Dave

wmonk · Posted: Sun Jan 09, 2011 3:39 pm Post subject:

Months ago in the year of the Lord 2010 I started this project. I guess now the year off the Lady started, it goes faster. Smile

My module was finished on January 8th 2011, and it sounds great Smile

I used FKP capacitors for C2 and C3 (metallized polypropylene film)
The pcb is attached to the panel with an L-bracket. Sounds have to be recorded, will do that next week. Cool

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Skrog Productions · Posted: Sun Jan 09, 2011 4:31 pm Post subject:

Hey Woody , cool sounds on the radio jam tonight , what kind if dials are you going for , moog style or mixer or soft touch mini dials ????

tazer · Joined: Oct 18, 2010 Posts: 49 Location: UK

Hi great modules guys!

wondering if anyone can give me a tip about mine, the output volumes are noticably quieter than my other filters. Could anyone tell me which resistor i could change and an approriate resistor value to fix it with, to boost the output volumes.

many thanks

http://www.musicfromouterspace.com/analogsynth/statevariablefilter.html[url][/url]

Skrog Productions · Posted: Thu Jan 13, 2011 10:56 am Post subject:

Hi tazer

I noticed that as well , i think it's to do with the state var. vcf using 1 LM13700 (6dB per side) , the 24dB filter obviously uses 2 LM13700's and is louder , i simply turn my vca up a little to compensate.
Unless you build 3 pre-amps maybe , one for each out (Ray has info on op-amp gain calculations in his how to / synth 101 pages on the mfos site) or you could run it through a simple vca to boost it.

Good luck Smile

Dave.

tazer · Joined: Oct 18, 2010 Posts: 49 Location: UK

Hey Dave

thanks for your speedy response, i should have known it wouldn't have been so straight forward as a resistor (maybe wishful thinking!). Thanks for the advice-have you got a link to your pics of your modular anywhere? I've only seen bits and pieces-it looks really pro. How long you been building it? I've been building mine for about a year and just finished my first cab, i'm gonna post up some pics soon. My wiring defo needs some work but that will come with time they turn into such a big project you need to be multi skilled-the modules i've seen of yours all look compact and neat though.

easy now

wmonk · Posted: Sat Jan 15, 2011 7:24 am Post subject:

Time for some samples.
The first one is a filter sweep as Dave did, using different settings of resonance. Every setting of resonance is played twice, with one having the band pass output inverted in the mix, the other all same polarity (those are somewhat more quiet).

The second is a sequence, again the sound source is a SN Voice pulse output. Using the different ouputs of the filter, first lopass, then bandpass, then highpass.

Last one is a fun trick with the VC Resonance to accent notes. Used gates to do this. Same sequence.

Have fun listening, I can really recommend this module! Smile

Oh, I know I'm using a 12dB/Oct filter for a bass sound, just wait till I get my Oakley Superladder done Very Happy

Cheers,
Woody

20110115-filtersweep.mp3

Description:

Filter sweep. Sound source is the SN Voice pulse out.

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20110115-filtersweep.mp3

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20110115-filteredsequence.mp3

Description:

Sequence with the MFOS SVF. Different output, different sound.

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20110115-filteredsequence.mp3

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20110115-sequence-vcresonance.mp3

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And the last one, same sequence with VC Resonance turned up, and played with gates. :-D

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20110115-sequence-vcresonance.mp3

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Skrog Productions · Posted: Sat Jan 15, 2011 10:38 am Post subject:

Nice sequence Smile

sounding good Woody.