Fortress vs Castle

Hey there folks, hope you are all doing well? I wondered if anyone had any thoughts on the differences between the Castle module and upcoming Fortress module? Doesnt seem to be much info about Fortress around but wondered what you experienced Castle module users thought about Fortress in terms of overlap, similarities etc. Also anyone know when Fortress will be available? Cheers!


No one except the developers and the testers have really used the Fortress, so it’s a bit hard to compare at this stage. I suspect when it’s closer to release, you’ll get more info.




So … a year later, Fortress is out in the wild - what are the pros and cons of Castle vs Fortress? :slight_smile: I really like the effects they both create, but hard to tell from a layman’s perspective what the differences are. :slight_smile:

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Fortress packs a whole lot of Castle features (and then some) into one module, which is a big PRO if you don’t have a lot of space. The advantage (for some) of the Castle series is that you get to build them yourself and focus on learning how each module in isolation contributes to your patch.


I don’t have a Fortress, so I may be totally wrong about this, but it also seems like the patching configuration is a little more controlled. It just works how it is supposed to work.

Whereas I think probably the coolest thing about some of the Castle modules I have is how you can patch things in unexpected/“wrong” ways and get interesting results. Like patching out from just the D0 or D1 output channels of the ADC gives you a crazy hard key version of the input.

In other words, I am not sure you can misuse the digital/analog divide as much in Fortress as you can in the individual Castle modules. But my perception of this could be more a function of people just generally using it how you are “supposed” to in demos and whatnot than actual limitation.


Brilliant. Thanks a lot for pointing that out. Much appreciated. :slight_smile:

Thanks for the input! :slight_smile: I’d actually like to build the modules, but have found the sourcing of all the parts to be a pain in the butt (can’t seem to find a full set of needed parts anywhere, there’s always something missing), so might just save up for the Fortress!

A few sourcing hints, in case it helps…

Usually you just need two sources when building a synth module (video synth or otherwise): A DIY shop source for your pots/jacks/PCBs/panels (like Thonk or Modular Addict) and a general electronics supplier for everything else (like Mouser or Digikey or TME).

Often people buy jacks and pots in bulk, too, since there are common ones used on lots of modules (for instance, all the LZX DIY modules use the same jacks and pots), and this helps widen the options of where you can then buy your PCBs/panels. Thonk especially is a good place that usually has the pots, jacks, pcbs and panels for LZX stuff, but they’re not shipping to the whole world currently due to covid (though they’re expanding where they’re shipping to progressively), so it may or may not be a good source for you right now but should be a good source in the future.

And as far as your everything-else electronics supplier, any of the big name suppliers will do. They might occasionally be out of a specific specified capacitor or resistor, but they always have substitutes. There’s nothing magic about the ones LZX specified, so use a different brand with the same key specs if you must (I believe there’s a thread here somewhere about sourcing alternative parts with good pointers if you don’t know what to look for). The only parts that really matter to get the specific ones specified are the IC’s. As with the jacks and pots, LZX uses a lot of the same general components (esp. resistors and capacitors) on all their modules, so you might as well buy a bunch of them if you think you’ll be building more modules. You could even put the BOMs into a spreadsheet and total how many of each are used total across the modules you want to build, so you can be sure to order enough. (Often when you order more of a component at once you get a better per-component price, too, so this makes the part cost per module cost less!)

That’s really helpful, thanks a lot! It’s the substitute parts that always put me off, when there’s a ton of them, then I don’t know if I should trust it or not - but your pointers on the matter is very valuable. Nice! Thanks. I feel safer about it now.

I’ve never really had any trouble sourcing parts for audio DIY modules, so it was a bit surprising to see so many parts “missing” from Mouser’s inventory.

Here’s a good answer to a common question (can you make a Fortress with Castles?), posted on the LZX FB Group:
Philip Baljeu
You can’t replicate it exactly with the available castles, but you can get close
3* the following :
Shift register

2* adc. (technically fortress has 3adc, but there isn’t a castle multiplexer, so third adc has no use, being that it selects the ALU mode)

7* dac

Counters and vcos for waveforms.
The multigates are to make most of an alu, but it lacks addition and subtraction.

Can’t replicate lfsr, addressable 3bit shift reg, or palettes, without serious module outlay, if possible at all.

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if made into a single though-hole module / panel, that would be enormous!
Worth it though, in my opinion.

Interesting would be a block schematic on how to patch it up .


Question on the palettes… Can these be modified beyond the preset options? Any chance of a Castle Color LUT module for dialing in palettes ?

The Fortress palettes are preset. You could of course modify with Mapper or other processing.

I’m currently experimenting by pairing Fortress DAC output with Octal Quantizer and Topogram before sending through Mapper and Color Chords.

Any chance that the CPLD pins allow for customizing the palettes? :wink:

Could you take the DAC output, put it through a Castle ADC then the 3 outs of that in to a Color Chords or other RGB Matrix?


I’ll try that, @Rik_bS!
I’ve found many ways to change the colors post-Fortress. I like the specific look of the colorization of the 8 preset Fortress palettes, I’d just like to be able to program my own palettes.

Unlikely… LZX (understandably) don’t usually release the code to their modules (they just release the compiled firmware when necessary). They’d probably need to release the code in order for you to add custom palettes to Fortress’s CPLD.