Nifty Rig

Received a NiftyCase today for a new Mutable rig. Here’s my plan module-wise, but I plan on doing some extensive mods to the case while I collect the modules.

Along the bottom 1U space I plan on building a 555 based VCO/LFO (maybe or maybe not with exponential cv, I think I have a tempco laying around somewhere), some vactrol LPG and VCAs, noise and S&H, a simple dual quantizer based on a chip I bought maybe ten years ago and never did anything with, some mults, and maybe some logic. We’ll see what all will fit comfortably.

Along the front (where the power jack, USB, etc. are) I’m planning a three or four channel mono to stereo mixer with mutes, pans, and aux sends to a dual PT2399 based delay fx circuit.

I’m also going to try and fit in an amp for some built-in speakers or at the very least for headphones and an internal battery pack for maximum grab-and-go.

Things will likely change considerably, but I’ll be chronicling the build here for those interested. First things first, let’s see if I can get these logos off without repainting…


0000 steel wool and acetone made short work of that. You can still see a bit of the shapes of the lettering, but I’ll probably be painting a finish coat after I do all the drilling anyways.

Now I’m going to have to make some decisions and finalize the master plan, or just drill a bunch holes and wing it.


I like your style! :wink:

You remind myself of a younger me.

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Oh DAMN! Looks so clean. Can’t wait to see the end result!

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Nice! I am finishing up some mods on mine, great platform for this. Sanding off the text was first.

I intended to repaint the case, but after sanding down the finish, I chose to keep the brushed steel and polish it. Still working to get the reflection I want, but it’s close.

I drilled two holes in the upper left bout (and an extra for the LED). This let me flip the built-in MIDI/audio mixer jacks, making room for 4 hp of line → modular level boosting on the right. I installed that module directly into the chassis and scrapped the faceplate for a cleaner look (and less labor!). Drilled/countersank the 8 jack holes and they look very nice when the nuts are installed.

I plan to add a duplicate mixer out on a minijack beside the flipped audio mixer inputs. (I don’t need the mini → phone jack conversion of the original, considering it doesn’t attentuate to line level). So…free DC-coupled, unity gain, inverting mixer! But this may get replaced with a VCA module.

Currently working on a passive latching circuit with inverting kill switch, to turn MIDI synths into drone machines/raw VCO sources. Might upgrade to an active relay so it can be CV-driven.

I’m surprised more people aren’t picking these up for modding. They’re affordable enough to avoid getting precious about. (I’ve only found one thread on Reddit with any kind of modding pics.)

@jeaux, would you be open to sharing schematics for your mods? I’ve been avoiding the investment in equipment/time so I can roll my own, but the quality/cheap/self-contained VCA IC’s out there are singing their siren song, so more mods may be fated.


Damn that steel looks great, I might have to go that route too! I’ll definitely share my circuits here as I build them. Most of them are still floating around in my head tho :crazy_face:


Master Plan v1


Thanks! I want to get it as close to a mirror finish as I can. Honestly, I love the brushed steel look as is. It has a nice hazy gleam. But I want to practice my sanding skills :stuck_out_tongue: .

With this finish, I think the case looks nice as anything else out there. And it’s invariably the cheapest route, apart from a scratch build. Let me know if you go for the bare steel look and I can share my experience getting it there (secret tip: auto supply store, body shop section).

I am digging your layout. I tried installing my modules upside down before modding, but didn’t get much ergonomic benefit from it. With the mods, your layout is such a smart way to pack in the utilities and keep them at hand. I also like your built-in battery pack idea, and the way you’re reconfiguring the MIDI inputs (going to have to nick that!).

Curious to know…how are you planning to layout new holes where they may collide with existing ones? I was lucky my first mod’s holes didn’t cause any physical conflicts. If I install another existing module, though, I might need to cut a rectangle out and mount things on short rails.

I was thinking of patching the existing jack holes with steel impregnated epoxy, then sanding and redrilling. Now that I’m not painting it, that would be pretty obvious.

I guess I could scrap the faceplate and paint a colored rectangle over just that area to cover any seams or epoxy ugliness. Any better ideas?

I actually used the existing holes as a basis for my plan so I wouldn’t have to patch anything. If you zoom in on my mock up the original ’to out’ jacks are marked yellow for reference.

I think filling holes is going to be tough without the ability to paint. All I can thing right now would be to put a metal plate over it in a symmetric way so that it looks intentional. The only other thing I can of is welding them but that can get ugly really quick.

If I think of anything else I let you know :+1:

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Thanks. If I keep modding, cutting a rectangle the length of the 1U face from scrap steel and insetting it on hinges/polishing might look cool. Would be easy to “pop the hood” and tinker with the guts.

Such gory surgery not yet necessary, though. :smiley:

Got all the definite holes drilled. I think the flanks on the top section might need some more thought before I commit though, hopefully it doesn’t keep me up all night again thinking about it :crazy_face:


Master Plan v2, I think this might be final


Decided to just repaint it white, the steel would look nice but all that sanding sounds like a chore, also painted the wood sides blue.

Breadboarded the quantizer circuit and realized the chip I have was an older version than I thought and doesn’t have the bank select. Going to repurpose the switch as a portamento control.


I think I’m done with all the body work, now for lots and lots of breadboarding.


Output circuit done. Stereo 1/4” unbalanced outs with volume control, headphone out with independent volume control, and a pair of midi 5 pin to TRS adapters.


Vactrol VCA/Mixer Channel

Breadboarded this morning and worked out the values. Should get it x3 built by the end of the week!

Then on to the Dual Delay module.


Worked more on the headphone amp. Added a big chunk of metal to shield it from noise it was picking up from the PSU. Also I discovered the shaft of the volume pot was not making consistent contact with the grounded body of the pot (cheap part?) causing substantial noise when adjusting the volume. Fixed it by tying a thread of wire around the shaft. Probably not the most rugged fix, but we’ll see.

Started building a mixer channel module. I love freehanding circuits but quickly realized I was going to run out of room if I didn’t plan it out.

Also got a pair of little Arduino speakers in to try out tomorrow.



After some frustration with a pot I soldered too hard, and tricky cold joint I got the first mixer channel working great now.

The other two channels are coming together quickly and are nearly done. Also got in a bunch of knobs. I spend way too much money on knobs :weary:


Mixer is done! Will post updated schematic as soon as I can. It was a tight squeeze but worked out in the end :muscle: