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Music from OS Signal to gate converter.
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Wild Zebra



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PostPosted: Wed Jan 18, 2006 1:59 pm    Post subject: Music from OS Signal to gate converter. Reply with quote  Mark this post and the followings unread

So what exactly can I do with this. http://www.musicfromouterspace.com/analogsynth/signaltogate.html
OK so I can play my guitar and trigger a EG or run through a filter or VCA.
But if I have a 1v/oct synth will it track? No, right? Just wondering about some applications of this module.

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Wild Zebra



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PostPosted: Wed Jan 18, 2006 2:25 pm    Post subject: Reply with quote  Mark this post and the followings unread

If a moderator reads this will you move it to DIY synths. I'm guessing it might be more appropriate there.
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Blue Hell
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PostPosted: Wed Jan 18, 2006 2:48 pm    Post subject: Reply with quote  Mark this post and the followings unread

Ok, moved it.

Seems like you could feed it all kinds of (probably best percussive) sounds to get a trigger for an enverlope generator. I can imagine one might want to fiddle a bit with the time determining parameters, for whch you'll have to find your own way, but then again maybe it's perfect as it is, don't know.

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Scott Stites
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PostPosted: Wed Jan 18, 2006 3:27 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey WZ,

I've used the MFOS Signal to Gate circuit to synchronize a sequencer/random sound generator to a master tempo when multitracking.

I recorded a clock track - I just ran a signal through a VCA gated by an LFO so that a pulsed signal was recorded to the track. I use a Korg D8 for recording, BTW. Anyway, after recording the fast blips onto a track, I panned that signal all the way to one channel, and ran the output of that channel through Ray's Signal to Gate circuit.

The Signal To Gate circuit turns the track back into a series of gates, and I applied those signals to a simple 8 step sequencer, an EG, and some other things that can be controlled by gates. I used a CD4013 to divide the fast pulse down to different rates right after the signal to gate conversion on some tracks.

So, then, when recording, the D8 would play that track for monitoring while recording each track. Because that track was controlling the sequencer, EG's and whatever else, everything was perfectly synchronized to one master clock. In this case, it doesn't matter how inaccurate your clock is, because it will never vary once it's recorded. I guess it's like SMPTE or whatever that was called. Or, a poor man's MIDI clock Very Happy


I made a couple of samples of it. Go to this page and sroll down to the bottom (it's actually my dual MS-20 filter clone page - I was running it through some paces at the time).

http://mypeoplepc.com/members/scottnoanh/birthofasynth/id10.html

The 'Synced Composition' sample at the very bottom shows how you can make a modular sound like a Casio keyboard accompaniment riff Very Happy

I got the idea by reading about some of Mort Subotnicks ghost methods.

He would get some fantastic results doing something along these lines, only using an envelope follower rather than a simple gate detector. IE, he would record *CV*' instead of gates. Good times.

Fascinating stuff:

http://www.buzzclick-music.com/mort_lore.html

Cheerio,
Scott
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Wild Zebra



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PostPosted: Thu Jan 19, 2006 7:17 am    Post subject: Reply with quote  Mark this post and the followings unread

Now thats a good Idea. Thats what I'm talking about. I really like the sound of that sample.

thanks

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Scott Stites
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PostPosted: Thu Jan 19, 2006 12:03 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks WZ. I imagine it could be done on anything that multi-tracks (computer programs etc.).

As for the sample, one of the things that is used in there is Ken Stone's Wave Multiplier. That's one of my favorite modules of all time - it does amazing things with triangle and sine waves.

http://www.cgs.synth.net/modules/cgs29_wave_multiplier.html

The bass voice in that sample is a triangle wave fed through the WM and sounds kinda like PWM. The high jangly part is also a triangle wave fed through the WM. I can't recommend that module enough! Once you start modulating the folds and offset inputs, it can really surprise you. I have the older version Ken put out before he added the extra Lockhart folder circuit section - a very simple yet effective design in itself for wave folding. I've breadboarded it, and it does a lot more than one would think as simple as the circuit is. Something like that might be pretty easy to insert into a SL for even more timbral possibilites. BTW, that's the same thing as Ken's "Simple Wave Folder":

http://www.cgs.synth.net/modules/cgs52_folder.html

The chords in the background (and what the samples end with) is my Korg DW6000 through a Korg PS3XXX resonator - another very cool circuit. The MOTM Triple Res filter and MaM RS3 Resonator are based off of it. The RS3 in particular takes it a step further.

Take care,
Scott
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Wild Zebra



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PostPosted: Thu Jan 19, 2006 1:59 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the indepth. I'll take a look at those modules. Ken Stone has some nice looking circuits over there. I poked around there for awhile before I discovered Ray's site. Ray's seemed alittle more beginner oriented. I still need a breadboard I think I would learn alot more by getting one and experimenting with these circuits. I just received some of ray's modules from a guy I met on Diy stompboxes a while ago. Both VCF's, signal to gate, Versatile LFO, and S&H with noise.
Figured it'd be a nice little jump start for a modular, getting a few at once. Now I have to decide on a PSU. Build or Buy? Paia PSU looks pretty good for the price. Then modules, modules and more modules,
that wave multiplier looks very impressive.

thanks take care

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Scott Stites
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PostPosted: Thu Jan 19, 2006 3:02 pm    Post subject: Reply with quote  Mark this post and the followings unread

Well, cool!!

I see a pretty neat thing you might be able to pull off with your guitar once you feel comfy with a slight bit of modification to the S&H:

IIRC, Ray's S&H runs off an internal clock. It may be a simple matter to modify it so that you could trigger it with an external signal. Maybe.....the signal to gate converter!

Say, run your guitar through one of the filters, control that filter with the output of the S&H.

Plug the gate out of the Signal to Gate into your newly added external clock input of the S&H. Plug the LFO into the signal input of the S&H.

Pipe your guitar through the signal to gate converter. Plug the signal out of the Signal to Gate into the filter.

Now the S&H will change the cutoff frequency each time the guitar signal exceeds trigger level for the gate. You could hit power chords, with each power chord having a different, randomly selected cutoff (wouldn't have to be powerchords, though). Putting a high slew on it would give it a sort of auto-wah flavor. This patch would be sort of a quack/wah box, only instead of the amplitude controlling the cutoff frequency, the amplitude determines when the cutoff frequency changes.

It would act as a S&H if you filter the gate to the width of a trigger. A cool twist would be if you just left the gate alone - then the S&H would act as a Track and Hold. In this case, when the guitar signal was high enough to hold the gate open, the filter cutoff would track the LFO input of the S&H. Once the guitar signal fell below the gate threshold, the filter cutoff would 'freeze' at whatever cutoff it was at until the guitar gated it again. In this case, it would be a cool gated autowah.

If you put a compressor between the Sig to Gate guitar signal and the filter, the amplitude of the signal could remain constant while you manipulated the guitar level to trigger the S&H. However, the compressor should be able to handle a fairly hot signal (you'll want to amp the guitar signal through the Sig to Gate in order to get a good S/N through the filter - synth level and all that).

The coolness of modular guitar effects..... Very Happy

Take care,
Scott
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Wild Zebra



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PostPosted: Fri Jan 20, 2006 8:28 am    Post subject: Reply with quote  Mark this post and the followings unread

Wow, thats sounds really cool. Can't wait to get it all up and running. I just got the poulated boards minus chips, so it'll be a little while. PSU, rack, Any advice on panel designs? Put a post in gen disc, to no avail (so far). I've got a friend who built a modular rig around the thought to be able to play guitar through it. Any thoughts on a Expression/CV pedal? I've got a dunlop wah that is shot. I did some poking around, but couldn't find exactly what I was looking for. That patch your talking about sounds a little A like my Korg x-911 in distortion mode. It tracks the signal poorly and It jumps the filter up and down. A lot less complex, though. It sounds awesome.

Thanks

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PostPosted: Fri Jan 20, 2006 11:00 am    Post subject: Reply with quote  Mark this post and the followings unread

Front Panel Express has a free panel designer, though I rarely use it. I use Visio, but, then again, I probably produce the world's ugliest panels.

An expression pedal shell is sure something I'd like to have around. If you want to use it with the synth, the easiest way to do it would be to just wire the input jack to the top lug of the pot, wire the center lug of the pot to the output through a 1K resistor, and the bottom lug of the pot to ground.

If the pedal has a battery or a power input, you can normal the input jack to +V with a NC switching jack, so, without plugging any signal into it, you have a 0 to +V CV. This would be exceedingly useful, especially once you get a VCA. Plugging a CV into it will disconnect the +V from the top of the pot and insert the CV signal. Then you would control the amplitude of the CV with the pedal.

Even if the pedal doesn't have a power supply, you can still plug a CV into it and use it that way. You could also plug a signal into it and control the amplitude of the signal with it as well.

The modular design gives you a huge amount of choice on what to do with the pedal.

Using a DC signal
This is where the +V is normalled to the input jack with nothing plugged into the input jack.

You could control the cutoff of the filter with the pedal (making it a wah pedal). You could control VCO frequency, LFO frequency (if you have a VCLFO or a VCO that goes to LFO frequencies), amplitude of the signal through a VCA or obviously anything that can be put under voltage control.

If you have a VCA, especially a DC coupled VCA, this greatly enhances what you can do. If you run the signal you want to control through a VCA, you can control the VCA with the pedal to increase or decrease the modulation or signal that's passing through the VCA. Doing it that way would only require one patch cord coming from the pedal. You could control the amount of 'autowah', tremolo depth (when using another VCA, conrolled by the output of this vca), VCO vibrato depth, the level and therefore range of a S&H input signal, the intensity of an EG, well, just about anything.

Attenuating a signal
This is where you would patch the signal to the pedal, through the pot, and back out to whatever it is you want to control. You could control all of the above with the pedal itself in that case.

There are many more apps you could do if you wanted to put circuitry inside the pedal, particularly an 'attenuating inverter'. An attenuating inverter is a control (normally a pot) that attenuates the signal fully when set to the center position. As you rotate it CCW, the signal that's passing through the circuit increases in level AND is inverted. As you rotate it CW, the signal that's passing through it increases, but it's not inverted. This is a powerful tool in synthesis, because you can now both invert a signal and control its amplitude, or not invert and control its amplitude with one single control. For example, if you run an EG through it and you can get inverted or non-inverted EG through it, while at the same time controlling the amplitude of the signal. You could make this function selectable with a switch.

In the case of the pedal, having this config would attenuate the signal at mid position. Rocking it back would increase the amplitude and invert and rocking it forward would increase the amplitude and not invert. Then, if you inverted the signal and made a second output out of that, you would have complementary signals. One would go one direction, and the other would go the opposite direction through the travel of the pedal. You could make it unipolar or bipolar. Control like this could produce panning or crossfading if using two VCA's, or any number of bizarro effects (try controlling both your filters with them - one going up in cutoff frequency while one is going down - a very cool effect when the signals are mixed together). Nonsymmtetrcial LFO waves such as sawtooths would work really well in different patches using this. Lots of stuff you could do with it.

I know it's a joystick control, but you could put the same circuitry in it as seen here:

http://home.comcast.net/~sbernardi/elec/og2/og3_joystick.html

Think of the pedal as a one axis joystick and you'll get the picture.

Take care,
Scott
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Wild Zebra



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PostPosted: Fri Jan 20, 2006 12:19 pm    Post subject: Reply with quote  Mark this post and the followings unread

Dang thats alot of info, Thanks. What value pot? Just use whats in it?
So if I hook a battery (9v) to it just hook it up like I would a stompbox ie. stereo jack. (no wait I want it off when I plug into it and on when nothings plugged in. I got that part. NC switch jack) Do I have to worry about running to much voltage into my synth. My soundlab is +5 volts OSC CV. Haven't done the zener diode protection mod. Sorry to sound like such a novice after you've explained everything so clearly, but I am. Still picking up on all the jargon and making sense of it.

Thanks you've been a fountain of info. I gotta get these suckers up and runnin.

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Scott Stites
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PostPosted: Fri Jan 20, 2006 3:04 pm    Post subject: Reply with quote  Mark this post and the followings unread

Sorry about the flood of info - I get excited about this kind of stuff.

Generally, on a modular, you can normally inject a signal up to the supply voltage of a circuit without worrying about damage. For example, if the SL is powered from 9V, you could get away with putting in 9V. Going above that might tempt fate. Even if the VCO only responds to up to 5V, going above that but not going above 9V shouldn't cause a problem, as long as the VCO is powered from 9V.

Be aware that inputs that specifically are for positive voltages can be damaged if the input is going straight into CMOS powered only from +V. Normally, the prudent designer will put in a diode that chops off the bottom half of a +/- signal so it is not a concern should someone plug a bipolar signal into a unipolar input by accident.

If you find that the pedal has higher voltage supply than the synth, you'd want to chop that voltage down. That's when we need to start thinking about zeners and so forth.

Pot value in the pedal can be anything 50K or higher in this case. Bear in mind that the pot will always be draining the battery to ground. In the case of a 50K pot and a 9V battery, it will always be passing .18 mA through the pot. A higher value pot will drain less. In any event, you'd want to be able to switch the power in the pedal on and off. Maybe the usual stompbox power switching scheme could be put on the output connector.

I've attached a schematic of a simple expression pedal, and also a general normalizing scheme for something like the Soundlab.

The pedal schematic has the +V going to the normally closed lug of the input jack through a 1K resistor. The 1K current protects against any inadvertent shorting out when plugging in a plug to this jack. In this case, the 9V goes to the top of the pot, and the pot determines how much voltage goes through the 1K output resistor. The 1K resistor is there for protection - again a very good idea. As you plug things in with the other side of the cable, you are almost guaranteed of brushing the plug against the ground plane of a jack - this 1K limits the amount of current that can pass through if you have the voltage on full - only 4.5 mA will go through it when you accidentally short to ground with voltage up the highest, assuming it's a 9V supply. Even with a 15V supply the current would only be 7.5 mA. Remember, the 1K connection between the +V and the jack, and the output 1K resistor are in use here. But, even if it were just the 1K output resistor in play, that still would be enough current limiting. Generally, most synth modules have a 1K output impedance - this is one of the reasons for that.

The module normalization I've attached has the added jack for normalling a synth input. Say you have a LFO that's hardwired to a VCO through a control pot. You'd just break the connection between the LFO output and the pot, and connect the tip connection of the jack to the pot while connecting the LFO to the normalling lug of the pot. Then, when you plug a plug in, whatever is on the plug goes through the pot to the VCO. Otherwise, the LFO still works upon the VCO.

Obviously, not just an LFO to VCO normalization can be done here, but any hardwired connection.

The point of this is that I use input attenuators everywhere - it gives a lot more control over what is going on in the synth. The only place I don't use them is with critical V/Oct inputs to VCO's or filters. I leave those alone and add the additional modulation inputs through pots.

Putting a level control on the output of a controller or module means that everything downstream is a slave to that one level.

With your expression pedal and an input attenuator on the modulation input of your VCO, you could adjust the max level of effect the pedal will have on the VCO with the input attenuator. This would be vital, because the full travel of the pedal could swing things waaaayyy too much. Attenuating the input of whatever you're controlling could make it so that you would have a lot more control of things - say the pedal range would only move the VCO an octave instead of five octaves.

Take care,
Scott


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Wild Zebra



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PostPosted: Mon Jan 23, 2006 8:20 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks alot Scott.
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Rolbista



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PostPosted: Sat Jan 19, 2013 11:37 am    Post subject: Reply with quote  Mark this post and the followings unread

The link at the top of the thread is dead, does someone have project files for this signal to gate converter? I'm currently bending a Casio keyboard, and all I have is the output signal, so if I could convert it to gate I could use the ADSR module that I have with it.
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elmegil



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PostPosted: Sat Jan 19, 2013 12:52 pm    Post subject: Reply with quote  Mark this post and the followings unread

http://www.musicfromouterspace.com/forums.html?MAINTAB=SYNTHDIY&PROJARG=OLDIESBUTGOODIES/CONTROLLERS/audiotogate.html&VPW=1268&VPH=770
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