Castle or Cadet?

Hi there!
I just found out about these awesome eurorack modules. I have been building a small audio eurorack system over the last year, lots of DIY modules from thonk.
Now I am absolutely keen to understand the basics of video synthesis. Basic beginner questions, I couldn‘t find an answer myself:

  1. What is the difference between the Castle and the Cadet system? Can I achieve the same goals with both of them?
  2. Which inputs can I connect?
  3. Can I show my output on every TV/LCD ?
  4. Do I need other modules to make those system work?

Thanks a lot,


  1. Castles are a series DIY modules based on CMOS logic chips. This means you will find modules that do flip-flops, shiftregisters and some other cool stuff, these modules are very good to lay patterns on your video compo. All the Castles are great for shaping and even colorizing in a 3 bit world!

Cadets on the other hand a the basic building blocks for creating a Video Synth. Every videosynth needs a sync (Cadet Sync, to generate timings for the whole system) module and a encoder module (Cadet Encoder transforms the analog signals from LZX 1v standard into PAL/NTSC).

The rest of the cadets are also basic building building blocks and very nice to have, i.e. VCOs, faders, mixers, ring modulators with bandwidth.

So if you want to get started with the modules you al ready have in your audio system you MUST get one Cadet Encoder and Cadet SyncGen at least.

From Cadets I recommend you to grab at least:

  • 1 x Cadet ramps, super basic for cool gradints or RuttEtrish patches :slightly_smiling_face:
  • 1 x Cadet video input, so you can input a video cam (cctv or ther cheapo composite cameras) into your modular
  • 2 x Cadet VCOs, even if you have some audio VCOs, having video bandwidth vco help you to create more complex shapes.
  • 1 x Cadet Multiplier (or two) - its basically a video bandwidth ring mod.
  • 1 x Cadet Fader (or two) - to fade between signals at video rate.
  • 1 x Cadet Scaler - to conver the modular level signals (bipolar 5v) to 1v. You will probably still need some attenuation on your audio modular but it will work.
  • 2 or 3 x Cadet Processor - a video bandwidth mixer, useful for both shaping and colorizing your compos.

From Castles: All of them… really they are very nice, but you can’t really use them without a Cadet Sync and Cadet Encoder, my favorites are flip-flops and shiftregister with the XOR chip. You can mix both Castles and Cadets, but you need at least the basic modules I keep mentioning Sync+Encoder.

  1. You can connect all inputs and outputs from your audio stuff into your video stuff, or vice versa. All Cadets, Castles, Visionary, Expedition and Orion series support bipolar 12v in all inputs. The bad thing of using a 10v audio VCO into a video module is that it requires a lot of attenuation and even when you get attenuators in all Cadets inputs, that means the control on the input is reduced because of the amount of attenuation you need so the range of the pot is not fully used.

Check the Cadet21 system for an example build of a Cadet based system.

  1. Yes if it has Composite input (at least to my knowledge).

  2. I think already answered this on (1) but let me know.


If you have envelope followers in your system they will be very useful for creating animation that is related to the audio signals you are generating with it (given you are trying to do both music and video in a performance) or to process external audio inputs.

If you have LFOs or ADs they will be very usefull to to create animation on your shapes.

1 Like

you can use quite a lot of your existing eurorack modules for video processing or modulation (you might need an attenuator) - most analogue and some digital modules will work

the recommended cadet system is 21 modules in total (just google cadet 21 - or look on thonk)

this gives you a nice basic video synth

another option which costs about the same is to buy a Visual Cortex as your main video i/o module and then add a few cadet/castle modules as you see fit - it works out about the same price

something to remember is that the VC supports color input whereas the cadet doesn’t

1 Like

That said, you can still do plenty of neat things with fewer than 21 Cadets, and with different distributions.


Wow! Thank you so much! This is far more than I expected! So kind of you for explaining everything in such awesome detail. :sunglasses:

1 Like