Performative, tactile control via kobs and sliders


I want to have a conversation about the design of audiovisual instruments with regard to tactile, hands-on performance. I would like to hear some artists and designers’ thoughts about this. How important or desirable is the ability to move a control quickly, with a musical feel?

The entire reason for the resurgence of knobs and sliders in synth design is due to the lack of intuitive controls seen in late 20th century instruments exemplified by the notorious Yamaha DX-7. Moreover, many artists have embraced hardware audio and video synthesizers precisely because they want the responsive tactile interface of knobs and sliders that can be difficult to achieve via PC software.

And yet, so many synths and modules, both audio and video, are designed with potentiometers that literally introduce friction into the performance. The pots resist being moved. It is not possible to use these pots as real-time parameter controllers in the same way one would use a musical instrument. The pots are just too slow to be moved as quickly as one’s hands can move.

This goes against my entire working methodology. I learned synthesis on Sandin, E-mu, Buchla, ARP, and Sequential Circuits gear, all of which have frictionless pots. (The E-mu modular in particular was a joy to work with, all-metal modules and knobs that were perfect for real-time manipulation.) I’ve also used gear that had slow and sluggish pots, e.g. Hearne/EAB, Roland. While I loved the fucntionality of those instruments, I was not a fan of their performative characteristics.

My current rig has modules from ten different manufacturers. Almost all of them use pots that resist being moved. I do not fully understand this design choice. Why would anyone want to undermine one of the key functions of hardware synthesis – real-time tactile control?

Is it because the available OEM parts are all designed this way? No, because there are some pots that don’t introduce friction. In particular, the @brownshoesonly modules use pots that I can move quickly and easily in a staccato motion, or move slowly and evenly in a legato motion. I think Nick gets it. His experience with live bands has informed his module design with musical performance in mind. I love the oversized knobs, as well. Yes, I know the V.HS modules are going to be more compact, and I guess that means the end of the big, sexy knobs that are so great for musical performance.

Are most pots slow and sluggish to prevent accidental changes from bumping the knob or slider in a dense forest of controls and cables? This does make sense to me. Eurorack real estate is extremely dense in comparison to historical designs. (The E-mu modular was huge, with vast swaths of empty space. Great for performance, but absolutely not portable.)

Knobs and sliders that are difficult to move are great for “set it and forget it” applications. Is that the dominant paradigm? Is the assumption that artists are going to set up a patch and let it run with little or no real-time manipulation? There is merit to that, but it shouldn’t be the only option.

Finally, I want to bring up the FKG3. Not having an ESG3 yet, I can’t fully test the new keyer module. But I have seen video demos by Nick and Johnny Woods. The Threshold pot has a fixed slew function built into it. This assures a “smooth” transition between key thresholds. I humbly suggest that this design choice does not take all use cases into consideration. One of my most favorite things to do is “ride” the key threshold; to play it like a musical instrument. This slew factor makes that impossible. It’s like someone built a musical keyboard that had a fixed portamento that was always on and could not be disabled. Or an envelope generator that could only produce slow attacks.

I’m really, really not a fan of the visual effect of changing the FKG3 threshold. It’s got a very robotic feel to it. By analogy, it’s like a computer animation that uses the default slow-out, slow-in Bezier tangents. This is something that only beginner rookie animators ever do. The very first thing one learns is how to adjust those curves to make the animation natural, interesting, believable.

I’m assuming that the Threshold CV input of the FKG3 does not have a slew on it, otherwise it would be useless at any frequency above one Hertz. So I can use an external controller to get the effect I want for this parameter, or any parameter that has a CV input. (My favorite is my trusty JL Cooper CS-10^2, a MIDI controller from the early 90’s that has nearly frictionless 110mm sliders.) But in a perfect world, I could use the physical controls directly built into the modules, and not have to resort to external gear and the ensuing greater patch complexity.

In future LZX designs I would like to see the tyranny of enforced slew rates abolished. I would much rather have full manual tactile control over the parameter than have to live with “smooth transitions”.


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Do you mean like a korn kob?


Electronic music emerged only recently from the longstanding timeline of music. The widespread distribution of electronic audio synthesizers was supported by a large body of preexisting experiential and academic findings. The parallels between video instruments and musical instruments aren’t as clear as the relationship between the audio synthesizer and the musical instruments that came before it.

If you are hoping to interface with your video synthesizer in a way similar to the electronic instruments you described, then there is a large catalog of expressive CV and MIDI devices that are compatible with the 1V standard Lars has established.

The equipment made by LZX, in my opinion, is still establishing possibilities and filling gaps not available in other forms. As you know, the development of certain video instrument critical tools is still underway. The tools available now, especially the Gen3 solutions, are the building blocks of a functioning video synthesizer. In my opinion, these blocks are not yet well established enough to take into consideration the expressivity and human interface you desire. They do, however, play well with many expression focused tools available from other retailers.

If we as a community want these tools to cope with the demands of being analogous to musical instruments, we will at some point have to spend more time using the tools and sharing the results. As it stands, there is possibly not enough conversation and exchange of video results to clearly outline the capabilities of eurorack video let alone begin the revision of these capabilities into a playable instrument as capable as the musical instruments we are most familiar with.

I have for some time been interested in the playable video instrument. I have not however found references or content from video artists who are willing to share how they play their instrument. I am under the impression that Lars faces the same challenge to some extent. How can LZX design more playable instruments if there are not more reports of how existing video instruments are being played? To approximate the experience of playing a musical instrument, some users must be willing to play with their equipment less and begin asking themselves how they can play their instrument more.


As the Euro world moves to compact, dense, feature-rich modules I would expect to see more CV control surfaces on the market.
For that is one of the benefits of modular, if a design choice doesn’t suit your use you can build/patch options that do.

I’ve planned a “control skiff” to use as the playable surface that sits on my desktop, to be patched in to the a/v racks that will stand vertically on a shelf.
Perhaps you could consider that option, and if you go DIY it’ll even allow you to choose the knobs that feel best for you.

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those big blue multiturn type potmeters are fantastic to play with. smooth and precise control over the parameters.
But I have not yet found one that can be mounted such as the 9mm Alpha vertical pot.
And they are super big / tall. (and expensive)


I’m down with control surfaces, both analog and digital. But I also want more module manufacturers to recognize the value in prioritizing responsiveness. For example, LZX Gen3 knobs feel great. Really f’n rock solid. Detente position is unmistakable, it just FEELS RIGHT. Knobs rotations are secure, they’re not going to move if bumped. But they are impossible for real-time staccato movement, it just can’t be done. And if there’s no CV input, things get really complicated. Now you need not only an external controller but a VCA just to get that performative feel that’s lacking from the module’s onboard controls.

You have to understand that not all people will want this type of realtime staccato movement out of knobs.


Yes, I find that, if I want that kind of chaos, I can get it using modules designed to produce chaotic CVs. They may be designed for audio, but they also work for video animation.

Nevermind the various modules and other devices for turning hand movements into CVs without knobs.


BTW, I’m currently transforming my video synth into two cabinets. Cab 1 will be the animation cabinet (mainly non-video modules). Cab 2 will be the core video synth (entirely Gen3).

Here’s an example of what I think an ideal animation cabinet might look like (for circuit-bending values of ‘ideal’):

Please note the triple Wogglebugs! Imagine the CVs going into video modules. However, I’d be happy with a pair of Benjolins and Sensory Translators. (I’m currently one Benjolin short. That may change.) Benjolin videos with constant knob-twiddling make me feel sick, but I love the self-modulating videos. This may also apply with videosynth videos.

Maybe some of us are more process than performance. :wink:

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I don’t disagree that it’s fun to have looser pots for performing but at the same time, on a modular with a bunch of cables snaking around the knobs, it would be hell trying to keep a patch in check without pots changing values due to cable friction.

My vote is for keeping the resistance of pots as is and convincing one of the fine DYI designers to create a 0-1v voltage offset generator/VCA module with a big, low-friction performance knob. I’d also like a DJ-style RGB cross-fader while where at it.


This is a great point! I had not recognized the nuances and expressive potential of the human-potentiometer relationship. Hopefully some module manufacturers will take note and begin abolishing the tyranny of the tight ass knob!

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This is a pretty hot take! I’ll respond with a couple points.

  1. Video is naturally quantized to the frame rate, creating a frequency division between the image and the animation/movement of the image. There’s an upper limit to how fast you want the knob to move to not disturb the image, and that’s about 33ms for SD video.
  2. The intention of slewing the bias pots and and the control pots for active (dual VCA based) attenuverters is to remove noise that can bleed into the image due to the potentiometer aging or due to fast, staccato movements that may disrupt the content of the image itself (transients that move faster than the frame rate.)

Here’s a quote from the Sandin IP distribution religion document, page 13 for the Adder Multiplier – this gives us a historical glimpse into this issue from the first generation of video synth performers:

  1. The FKG3 threshold control is slewed more heavily than the general slew on Gen3 controls. Judging from the above list, it is a “100uF” option, whereas our typical slew is more like the “20uF” option described above. This is a performance minded feature that was arrived at after many years of reflection. With a keyer threshold during live performance, if you want sharp threshold transitions you would typically modulate the threshold with a stepped control source. If you are adjusting the threshold manually, you are typically intending to create a transition. This threshold transition reveals a range of intermediate frames that create the impression of motion. Even if you are moving the knob fast or to a beat, this still works out to your advantage as you will be revealing all those intermediate frames in time to the music, creating a cycling animation. If you want stepped or sharp transitions, there are better tools for that job, like frame rate clock dividers or frame-quantized pseudorandom/S&H.

  2. FKG3, despite it’s name, is not the same module as the Visionary TVFKG at all. FKG3 is a “Color Component Keyer” and TVFKG is a “Triple Crossfader + Triple Comparator”. One is a complex single function, and the other is six discrete simple functions in a semi-modular arrangement. If you look at the mathematical models for how each works, it should reveal the reasons for this. I would still like to do a “Triple Crossfader + Triple Comparator” or equivalent modules, but the single function “Component Keyer” is an important building block that I feel empowers some important core workflows in a single step up front. So that’s why it is where we started in Gen3.

Modular instruments are full of both complex integrated single functions and discrete raw functions. From an instrumentation perspective, both are important to conceptualizing and patching video processing workflows. The “fader” or crossfader is a great example of this. Under the scenes, this is a complex integrated function involving a Dual VCA, one being driven high while the other is low, controlled from a single CV source. But if you had to patch every crossfader out of dual VCAs and summing blocks, this becomes laborious – which is why a fader/crossfader is an important instrumentation building block.

More examples of complex single function blocks in a video synthesis workflow:

  1. Colorspace converters (triple fixed gain summing amp)
  2. Polar to cartesian transform (combo of dual VCA, dual sine shaper, quad rectifier)
  3. Rotation/affine transform (quad 4-quadrant multiplier, dual summing amp)
  4. Gamma (log/expo shapers and dual VCA/crossfader)
  5. 3x3 CSC/Matrix transform (SMX3, for example)

In these kinds of posts in the future, it would be quite helpful to be shown a practical demonstration of the issue, along with a video recording. I can perhaps reveal some context that may help you understand the instrument in a way you have not yet considered. Discrete measurements are also helpful, such as “I have measured the slew to be ~500ms and would prefer something close to ~100ms”.


So I think that your FKG3 might be malfunctioning. I purchased an early one and the softness knob stopped working properly. I took some captures and contacted @Z0NK0UT. He saw the captures, emailed me an RMA, and within a week I had my module back. I was shocked at the return time.(:clap:) The FKG3, more specifically a system with multiple FKG3’s is amazing. That module is one of my favorites.

Truth be told, I prefer stable knobs. I like using something like a Instruo 2[f] for performative techniques because any damage I do will be to the (less expensive) controller module. It really seems like maybe you should go the DIY route and make your own controller. Then you can make something with the knobs that you want. Or, you could find a midi controller that you like and convert that into 0-1v

If your FKG3 is working fine, and you’re still unhappy with the threshold response, maybe premix the Threshold cv? VH.S submix might solve your sloping issues as well as the one you have with knob friction.

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The impression you get may be shaped by the videos you choose to watch. I tend to avoid videos with rapid knob twiddling and endless camera movements. I have no difficulty finding videos that satisfy my tastes, but I know I would also find many rapid knob-twiddling videos without any trouble. This is just my selection bias.

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Lars, I totally understand your design intent, I just don’t agree with a lot of it. Really the only part of your post that I can fully get behind is slewing the pot input to eliminate noise from dirty or aging components. That is definitely an issue, I saw it with both the IP and the EAB.

I really strongly disagree with the idea that transitions (e.g. key threshold) need to be slowed down for performative reasons. I know you’ve thought about it. I know you have years and years of experience. But I also know that you are open to user ideas. And from my perspective, it’s a bug, not a feature. The musical performance I seek likes in the gap between your slewed pot and an external stepped voltage.

As for the assumption that there’s no reason to ever make transitions within the frame… no. Just no. It’s completely legitimate to have events take less than one frame to occur. Yes, you get vertical banding. Yes, very sharp transitions will create tearing. But that’s not necessarily a bad thing. And the limitations imposed by quantizing all events to whole frames/fields outweigh the benefits. Just as I was saying about latency in a decoder/TBC … the same thing applies here. I need to have the ability to control whether or not a slew or delay exists.

A product can’t be all things to all people, you have to make utilitarian decisions that you think will benefit the largest segment of your customer base. I’m just trying to offer my thoughts regarding my own needs vis-a-vis the tools, and see what other people have to say.


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Oh, and I would love to post video examples… that will be possible soon with the imminent shipping of ESG3. Whoo-hoo!

How fast can you sweep the knob full scale, in milliseconds? Let’s get this quantified so it becomes an engineering question of “how far off is the FKG3 threshold slew from your desired performance” instead of a design critique. We can look at that number and I will definitely take it under advisement when it comes to the ongoing system design.

As for the assumption that there’s no reason to ever make transitions within the frame… no. Just no. It’s completely legitimate to have events take less than one frame to occur.

I didn’t say that, I said that a bias control knob is a poor tool for that job. Moving the knob will always create a multi-frame transition – that’s just how human hands work. If you disagree with that statement, I need some measurements! The slew is there to smooth out that transition (which already exists, when you adjust the knob with your fingers.) If sharp transitions is what you want, you should be modulating the threshold with a mix of square waves. If you want the mid frame glitches, any square wave will do. If you want quantized transitions, you need S&H or square waves divided from the frame clock or VSYNC.


What are you currently using for an encoder?

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I tend to side with the folks that are saying that this kind of feature is something best offloaded into a controller of some sort.

Having a macro control module with some combination of the Cortex transition section (having manual, automated, VC, and trigger options is nice), the multi-routing of ADDAC 306, and control over transition slew — all in a 0-1v range — would be cool.


I think these documents speak for themselves. To be honest I am starting to think FKG3 was some sort of inside job.