Multi Space Filter

[StephenGiles]

I am back to just the basic working sweep generator. I'll be trying other VCFs as the SSM2164 was totally unsuccessful.

[StephenGiles]

Back to original Space Drum sweep generator - the CA3094 version, now to marry it up with the Microsynth VCF

[liquids]

Just heard samples of the Frostwave Funk-a-Duck and now I am dying for a intense near-oscilation filter or the EH synth filter and the like!    I guess I need to dive in and continue messing with filters, as I don't understand them and not building any isn't helping...

I'm really interested in what you find though.   Also, is your return to CA3080 and CA3094 OTAs mean the 13600's and 13700s are out for some reason?

[liquids]

1c3b and 1C4b  Schematics you have the buffers as 1 and 9...you want to correct the schematic to 10 and 9 no?  Good news for you Stephan, messing (albeit unsuccessfully) with Rick's Multimode LM13700 gave me the 'confidence' to give this one a shot.  Bad news is I will be gone until sometime next weekend, so you may have to wait a week to hear I'm having a miserable time getting it to work.....but it seems like I'll be able to breadboard half (the lower end where it looks to be LP sweep) of it fairly quickly, in theory.  To be continued. 

[StephenGiles]

Just heard samples of the Frostwave Funk-a-Duck and now I am dying for a intense near-oscilation filter or the EH synth filter and the like!    I guess I need to dive in and continue messing with filters, as I don't understand them and not building any isn't helping...

I'm really interested in what you find though.   Also, is your return to CA3080 and CA3094 OTAs mean the 13600's and 13700s are out for some reason?

Only 3094 - why? because I have 3 left!

[StephenGiles]

1c3b and 1C4b  Schematics you have the buffers as 1 and 9...you want to correct the schematic to 10 and 9 no?  Good news for you Stephan, messing (albeit unsuccessfully) with Rick's Multimode LM13700 gave me the 'confidence' to give this one a shot.  Bad news is I will be gone until sometime next weekend, so you may have to wait a week to hear I'm having a miserable time getting it to work.....but it seems like I'll be able to breadboard half (the lower end where it looks to be LP sweep) of it fairly quickly, in theory.  To be continued. 

The text box in Excel has covered over the 0 in the 10 - I need to make the text box larger. I draw in Excel at 200% size.

There is no hurry my friend, we are off to Italy for a week soon and my wife tells me I have things to do!

[liquids]

There is no hurry my friend, we are off to Italy for a week soon and my wife tells me I have things to do!

Sounds familiar     I guess I am not the one in a 'hurry!' So many projects (solder and non-solder related), and circuits that are 'good but not quite' have distracted and dulled my enthusiasm on my hunt for the right filter...but my enthusiasm has been revivied!..now only to fight for the time 

[liquids]

I confess...I still haven't tried this, because since not long after my last post, most because I spotted a used and affordable Microsynth.  I stalked it, debated over it for weeks while no one else grabbed it, and now have finally have given in.     That's the filter section I've been dreaming of...

I didn't build it, no, but it's awesome!  Practically speaking it's mostly a toy, but I like this kind of toy.   The filter only has so many usable settings, it seems.  I would hardwire the resonance to max, for one.  Likewise, the rate of sweep has a limited useful range to me.  And depending on if you want up or down sweep, I always have one of the frequency sweep sliders at max (that is, starting or ending with the highest possible frequency)--since I want down sweep, the start freq would probably be hardwired at max.  Even still, it's killin!  Stevie Wonder! 

I really see why for those non-synth 'up sweep' sounds you want it to follow the guitars quick decay.  That is the cool sound. For that sound I found even the simple phuncnosis and other typical envelope-based filters satisfying if not ideal, and useful -- maybe I'm just not too picky about 'up sweep' since I rarely mess with it, and I feel satisfied and convinced that I could build something simple for that typical 'up' envelope guitar sweep...

I will say that with the Microsynth filter, if you dont use something harmonic laden (square wave or octave up) to some degree, it is on the other hand pretty booringly subtle.    The synthy down sweeps-evenly swept, fast and/or medium are in here, and it's killin! 

After messing with the 'final product,' I do still plan on breadboarding one, but not till far later...I realize that the space filter is not exactly the same, but imagine it is similar enough, only looked at the schems and not having heard it. I will say that if anyone wants to build one, it sure seems like it would be worth it, especially if you could somehow get even MORE resonance and the like...I was endlessly trying to get my q-tron to sound like this, and got close, but thsi thing got some of the filter sounds I was itching for immediately...lots of potential 

[StephenGiles]

I confess...I still haven't tried this, because since not long after my last post, most because I spotted a used and affordable Microsynth.  I stalked it, debated over it for weeks while no one else grabbed it, and now have finally have given in.     That's the filter section I've been dreaming of...

I didn't build it, no, but it's awesome!  Practically speaking it's mostly a toy, but I like this kind of toy.   The filter only has so many usable settings, it seems.  I would hardwire the resonance to max, for one.  Likewise, the rate of sweep has a limited useful range to me.  And depending on if you want up or down sweep, I always have one of the frequency sweep sliders at max (that is, starting or ending with the highest possible frequency)--since I want down sweep, the start freq would probably be hardwired at max.  Even still, it's killin!  Stevie Wonder! 

I really see why for those non-synth 'up sweep' sounds you want it to follow the guitars quick decay.  That is the cool sound. For that sound I found even the simple phuncnosis and other typical envelope-based filters satisfying if not ideal, and useful -- maybe I'm just not too picky about 'up sweep' since I rarely mess with it, and I feel satisfied and convinced that I could build something simple for that typical 'up' envelope guitar sweep...

I will say that with the Microsynth filter, if you dont use something harmonic laden (square wave or octave up) to some degree, it is on the other hand pretty booringly subtle.    The synthy down sweeps-evenly swept, fast and/or medium are in here, and it's killin! 

After messing with the 'final product,' I do still plan on breadboarding one, but not till far later...I realize that the space filter is not exactly the same, but imagine it is similar enough, only looked at the schems and not having heard it. I will say that if anyone wants to build one, it sure seems like it would be worth it, especially if you could somehow get even MORE resonance and the like...I was endlessly trying to get my q-tron to sound like this, and got close, but thsi thing got some of the filter sounds I was itching for immediately...lots of potential 

So I take it that you do like the Microsynth filter and it's sweep? But it would be much improved if the start frequency peak when a note is played, follows the strength of the note instead of just starting at the point set by the start frequency slider, leaving the smooth downward/upward sweep as before. I'm still thinking about it rather than doing anything - busy at work so brain dead in the evening!

[liquids]

So I take it that you do like the Microsynth filter and it's sweep? But it would be much improved if the start frequency peak when a note is played, follows the strength of the note instead of just starting at the point set by the start frequency slider, leaving the smooth downward/upward sweep as before. I'm still thinking about it rather than doing anything - busy at work so brain dead in the evening!

I do! I see the benefits of envelope sweep for guitar, but in general, the tone I'm searching for is that fast high to low "BOW!" sound.  No envelope filter I've tried but the Q-tron could duplicate that sound, and at that, only when it was 'overloaded.'  The Microsynths sweep speed can go much faster, and much slower than an envelope.  Guitar envelope is pretty fast - but when you have an 'attack speed' control on a envelope, it just makes it more or less sensitive to the input envelope(?), not slower or faster.  The microsynth sweep is even.  Again, if you want it to sound guitarish--Garcia, bootsy, LA funk, or the other 'quacky' filter sounds (which according to you are not what you want), any standard up sweep envelope filter is better (though the sounds the funk-a-duck based on the MS-20, since it has extreme resonance, are amazing).  If you want anything synthy, the steady fast/slow sweep dictated by pot rather than envelope has great advantages and can hardly be considered a sacrifice, in my opinion.   I'd be interested in what you think of a Boss SYB or the Digitech Synth Wah...other than their tracking.

That being said, if you want a 'variable' filter sweep speed, you probably want a triggered ASDR voltage generator feeding the filter, over 'tracking' the initial dynamics and then going to manual sweep...because then you can have any sweep shape you want....

[StephenGiles]

So I take it that you do like the Microsynth filter and it's sweep? But it would be much improved if the start frequency peak when a note is played, follows the strength of the note instead of just starting at the point set by the start frequency slider, leaving the smooth downward/upward sweep as before. I'm still thinking about it rather than doing anything - busy at work so brain dead in the evening!

I do! I see the benefits of envelope sweep for guitar, but in general, the tone I'm searching for is that fast high to low "BOW!" sound.  No envelope filter I've tried but the Q-tron could duplicate that sound, and at that, only when it was 'overloaded.'  The Microsynths sweep speed can go much faster, and much slower than an envelope.  Guitar envelope is pretty fast - but when you have an 'attack speed' control on a envelope, it just makes it more or less sensitive to the input envelope(?), not slower or faster.  The microsynth sweep is even.  Again, if you want it to sound guitarish--Garcia, bootsy, LA funk, or the other 'quacky' filter sounds (which according to you are not what you want), any standard up sweep envelope filter is better (though the sounds the funk-a-duck based on the MS-20, since it has extreme resonance, are amazing).  If you want anything synthy, the steady fast/slow sweep dictated by pot rather than envelope has great advantages and can hardly be considered a sacrifice, in my opinion.   I'd be interested in what you think of a Boss SYB or the Digitech Synth Wah...other than their tracking.

That being said, if you want a 'variable' filter sweep speed, you probably want a triggered ASDR voltage generator feeding the filter, over 'tracking' the initial dynamics and then going to manual sweep...because then you can have any sweep shape you want....

I'm not sure you fully understand what I'm getting at, but thanks for your interest.

[StephenGiles]

I asked for this thread to be renamed Adaptive Space Filter - wake up Aron

[StephenGiles]

There could be some mileage in this circuit snippet.

http://www.4shared.com/file/102965602/2113ecbe/minisynth_sweep.html

It needs a trigger and a VCF.

[StephenGiles]

Perhaps an LM 324 peak follower for the trigger and a CA3094 based VCF or should that be a CCF?

[igor12]

Stephen,
I just breadboarded your space drum  envelope generator and it's not working (yet). You're using a single supply right? Just want to make sure you're down arrows aren't referring to a neg rail. I'm using a +9v. I had to modify the LM324 section for a Vbias voltage to get that part to work. For testing, I am inserting a 4.7k res to gnd on pin 8 of the LM13600 and scoping the signal there.  I expect I should see a rising voltage when I pluck the string, right?

[StephenGiles]

The voltage should immediately ramp up and then fall to the voltage set by the Stop Frequency pot at a rate set by the Sweep Rate pot. I do not recall the need for a vbias voltage on the 324 preamp.

[igor12]

The LM13600 isn't using a bipoloar supply, correct? In other words, there are no biploar supply in your circuit, (virtual gnds don't count)

[StephenGiles]

The LM13600 isn't using a bipoloar supply, correct? In other words, there are no biploar supply in your circuit, (virtual gnds don't count)

Correct

[igor12]

OK, breadboard works.  The trick is to follow your schematic!  I got thrown because the bottom half of the waveform was lopped off by the LM324, so I figured incorrect biasing issues. Apparently this is correct and I guess what the 13600 wants to see.  I wonder if traditional  biasing (4.5Vbias) and using full wave rectifier on the lm324 would work/sound better.

[StephenGiles]

Jolly good, someone believes me!! The 324 is just being used as a peak follower to energise the 13600 here so no point in fwr.