Adapting the EuroRack audio world for video synthesis

Discussion of modular and standalone video generating/processing techniques and associated hardware.

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Matos
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Post by Matos » Mon Jan 09, 2012 9:41 pm

You guys got me excited. Half my doepfer us due to your suggestions. Great ways of making a small system flexible.

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lizlarsen
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Post by lizlarsen » Mon Jan 09, 2012 9:47 pm

The module that's still getting the most use by me is the quadrature VCLFO -- I love it!

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daverj
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Post by daverj » Tue Jan 10, 2012 12:33 am

The LM324 is an old quad op amp with the same pinouts as most common op amps (like TL074). It's often used because it is very low power, and it's slow bandwidth helps keep CVs smooth if they don't need to go really fast.

It's a bipolar op amp instead of a FET input like the TL074. In some designs this can be an issue, in others it doesn't matter. It depends on whether the designer was just going for the low power aspect, or was using the characteristics of the bipolar inputs as part of the design.

Chances are you could substitute a TL074 and get 3 times the bandwidth, but without a schematic I can't be sure. You might be able to go with an even faster chip, but again, without knowing the circuit it's not easy to predict. Faster chips can often oscillate when substituted because the design doesn't take into account the characteristics of the faster amp.

For general shapes and patterns you don't always need a faster chip unless you are going for extremely fine detailed shapes or sharp edges.

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lizlarsen
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Post by lizlarsen » Tue Jan 10, 2012 10:48 am

Maybe I will order one of these and give it a shot, soon. It's nice that the op-amps are socketed in Doepfer modules.

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MrDys
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Post by MrDys » Tue Jan 10, 2012 11:36 am

I think I have some TL074's laying around, so I'll try this out when I get a free minute.

I also e-mailed Doepfer to see if they have any kind of advice on the matter.
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lizlarsen
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Post by lizlarsen » Tue Jan 10, 2012 11:38 am

If you get oscillation, that might possibly be solved by adding a small (2pF?) cap between the output and inverting input pins. It'd be nice to have schematics for all the Doepfer modules, then we could document full mods for those that could possibly be upgraded bandwidth-wise.

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Post by MrDys » Tue Jan 10, 2012 1:27 pm

Dieter is amazing. Nicest guy in the world. He responded:
You may replace the LM324 by other pin-compatible op-amps (like TL074). Nothing can be damaged and the circuits are cheap. ... Maybe some frequency compensation is required for faster op-amps.
darenager wrote:I wonder how many people with Maths don't know it can file a tax return, or that Plague Bearer can indeed give bears the plague
suitandtieguy wrote:STG IS ALL ABOUT THE PLUR.

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MrDys
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Post by MrDys » Fri Jan 13, 2012 11:31 am

So, I didn't end up having any TL074's laying around like I thought I did. I'll have to pick some up this weekend.

I did try out the A-136 on a video signal, though. I got some interesting effects, but the fidelity was pretty low. Definitely got some solarization-like effects. I'll have a video demonstrating it when my internet at home stops being stupid.
darenager wrote:I wonder how many people with Maths don't know it can file a tax return, or that Plague Bearer can indeed give bears the plague
suitandtieguy wrote:STG IS ALL ABOUT THE PLUR.

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MrDys
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Post by MrDys » Sat Jan 14, 2012 6:00 pm

Picked up some TL074's today. Did something of a side-by side comparison with the LM324:

[video][/video]

The LM324 is first and from about 2:45 onward it's the TL074. There's definitely more fidelity in the TL074, but they seem to have slightly different effects. I really like the effect in the TL074 version when the levels are cranked and it gives it a kind of analog-vectory appearance.

I may have to have two (or more) of these modules with different chips in.
darenager wrote:I wonder how many people with Maths don't know it can file a tax return, or that Plague Bearer can indeed give bears the plague
suitandtieguy wrote:STG IS ALL ABOUT THE PLUR.

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lizlarsen
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Post by lizlarsen » Sat Jan 14, 2012 6:04 pm

That's some really beautiful stuff! Another reason to have two of them would be for RGB processing -- one each of a module like this send to RGB outs (but with a common source) should give a very cool solarizer/colorizer. Another thing to try to add more "voltage control" to this effect is to sum an LFO with the video signal before sending it to the distortion module.

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johnnywoods
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Post by johnnywoods » Sat Jan 14, 2012 6:27 pm

Very cool! I got to play with a prototype LZX waveshaper circuit when I was in Australia, and it was an amazing tool. Although it's meant to do some specific color conversion tricks, it is also capable of beautiful solarizations.

I've done some RGB processing with the Toppobrillo TWF, and the results were very cool. Need to play with that some more.

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lizlarsen
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Post by lizlarsen » Sat Jan 14, 2012 6:28 pm

We'll have the video waveshaper prototype at NAMM next week and will upload some video demos of it in action!

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barto
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Post by barto » Sat Jan 14, 2012 9:15 pm

nice comparison! i didnt really understand what you guys were talking about before

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daverj
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Post by daverj » Sun Jan 15, 2012 9:56 am

Nice lo-fi processing. The images worked well with the effect

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numan7
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Post by numan7 » Tue Jan 17, 2012 10:25 am

[video][/video]

here's a quick demo i made of SoS processing signals from a VWG (as well as being modulated by another VWG, starting at around 4:00). while it isn't the most precise effect in the world (nor is intended to be), i think it can do some fairly interesting stuff.

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Post by smrl » Wed Jan 18, 2012 9:35 am

Yeah I've played around with a couple of homebrew delays I've built around the PT2399 with video - it's interesting but extremely bandwidth-limited - has a minimum delay time that's not quite short enough for video stuff in my opinion, if you're doing some horizontal band type stuff and get the timing just right you can get some nice smooth cascading bands. I don't think voltage-control is all that beneficial, using VC feedback might be nice but you have to get the timing just right to get some coherent stability out of it, otherwise it just looks like a garbled mess. There are probably better delays out there for working with video, i'd look for something that can go down to shorter, 'chorus' rates...

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lizlarsen
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Post by lizlarsen » Wed Jan 18, 2012 6:03 pm

Yeah, even an extremely short delay (a couple hundred nanoseconds for example) at decent video bandwidth could create wonderful things within a feedback patch, especially if voltage controllable (also at video rate!)

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zapp550
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Post by zapp550 » Wed Jan 18, 2012 7:40 pm

This thread got me started on running video through some of my stompxoes , very fun stuff :goo:. I'll try and post some of the results this weekend.

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Post by MrDys » Wed Jan 18, 2012 8:37 pm

On the A136 front, I've gotten good results tonight by inputting the video signal into the "Ext Level" inputs and skipping the "Input" input entirely. Worth a shot if you're experimenting with non-video modules.

Speaking of which, the STG Wave Folder does excellent work as a solarizer, too.
darenager wrote:I wonder how many people with Maths don't know it can file a tax return, or that Plague Bearer can indeed give bears the plague
suitandtieguy wrote:STG IS ALL ABOUT THE PLUR.

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Post by wcfields » Thu Mar 08, 2012 9:02 pm

Just ordered the Sandin kit modules and added a Doepfer A-144 Morphing Controller to the order.
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Post by giorgio » Fri Mar 09, 2012 12:56 am

also ordered both kits
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I'm pumped for the edge extraction, I've been using keyers to do it up until now but I'll be more than happy to use the TVFKG for other duties.
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Post by nickciontea » Mon Mar 26, 2012 2:01 pm

[video][/video]

The WMD Synchrodyne is a wonderful module for people who want to supply both an audio synth and a video synth.

It syncs nicely w/o amplification of the LZX VSG signal.
Sawtooth core runs upto 400kHz.
PLL opens up a world of tinkering and possibilities.
The filter works nicely in HP modes
Wavefolding is icing on the cake.

This video's output is entirely SYNCHRODYNE.. One VWG for FM

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Matos
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Post by Matos » Mon Mar 26, 2012 2:44 pm

Nice video. I was curious about its video prowess. Looks like a winner.

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lizlarsen
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Post by lizlarsen » Mon Mar 26, 2012 2:46 pm

Very exciting!
Stable line rate sync + 400KHz range = the second truly viable video oscillator in Euro outside of the VWG!

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Post by nickciontea » Mon Mar 26, 2012 5:38 pm

[video][/video]

dont think this one was posted in this thread. interesting waveforms

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