The Applesauce Modular Mark V

This is the story of the genesis and evolution of the Applesauce Modular, a new synthesizer that I have been putting together since May 2020.

My journey into electronic music started with a modular synthesizer. The story of the "El Dinosaurio" modular synthesizer has its own page, but suffice to say that at the time I could not afford to buy a synthesizer, so the only choice I had was to build one from scratch. The first synthesizer I built was a clone of the ARP Oddysey, but the second was an original fully modular design inspired by several circuits I had seen over time. It worked, I learned a lot about sound and electronics, and I got started in electronic music. "El Dinosaurio" was forgotten for a long time as I upgraded to digital synthesis and computer control (starting with a CZ101 and a Commodore 64 with a MIDI interface!) but it came back with a vengeance when I brought it back from Buenos Aires in 2007 and made it work again.

A new modular

For quite a while I have been receiving generously donated "research funds" from Joan/Mark Applebaum (Composition Faculty @ Stanford) on a yearly basis, no strings attached. The money was parked in a research account as I never could make up my mind what to spend it on. The COVID19 pandemic, which isolated all of us into sound and music bubbles, pushed me into starting a journey I had been considering for a while: getting a new Eurorack modular synth (and emptying the research account at the same time!).

So now I had a chance to look at this anew and explore the interactive, manual, realtime, non-repeatable universe of the sounds a modular can create.

Booting the system...

As soon as I started looking for available options (May 2020) I realized this was not going to be an easy project. It looked like I was NOT the only one on this journey, and quickly found that many of the most popular and useful Eurorack modules were hard or impossible to find. My first lazy thought was to get a big pre-built modular. I was looking at the Make Noise "Black and Gold Shared System" as a shortcut to a fully operational system, but it was nowhere to be found. So I started building my new modular from scratch, which ended up being a very good thing to do.

First I had to decide on a housing or rack for the modules, preferably one that would be travel friendly. After much research I decided to get an Intellijel 7U Performance case, which was flight-ready and would fit in an overhead bin (for the distant future in which travel is again possible and concerts can happen elsewhere in the world). There were other options - I was almost ready to buy a Make Noise 7U case, but the Intellijel won because it was available and it had an additional free 1U space in addition to the two 3U racks (I was looking at 104 HP wide cases - the search took some time as it was a hunt for reputable online sellers that happened to have what I needed in stock). This first purchase happened on May 26th 2020.

Much time was spent in the initial search for which modules to buy. My initial goal was to start by getting a traditional synth voice: oscillator, filter, amplifier and envelope generator. I found many options, and "Stage #1" of the process started with some modules that seemed like no-brainers to me at the time. Most of the research was in fact looking at various online resources that listed modules you "have to have", or at the "most popular modules" listings in (for example) MODULARGRid. This was followed by reading reviews, watching demos, downloading and browsing the manuals for the modules in question, and finally balancing needs and cost and deciding on a particular module. Even when I decided to get a module, availability was a problem, and I was checking all over the internet for sellers that had what I needed in stock (sometimes what I ended up selecting a different module based on availability). I started with this initial set of modules:

Stage #1

  • Make Noise, DPO: an dual analog oscillator with a wealth of cross modulation options
  • Make Noise, QPAS: a quad state variable filter with a very distinctive "voice"
  • Mutable Instruments, Stages: a very versatile and configurable envelope generator, low frequency oscillator, etc
  • Make Noise Maths: a very versatile control voltage processor and modulation source

This is the start of a very basic "voice": a dual oscillator, stereo filter, programmable envelope generator and a general purpose modulation source (the VCA was incorporated later).

A few more purchases added these modules:

  • Mutable Instruments, Plaits: multi function digital oscillator with 16 different synthesis models
  • Mutable Instruments, Ripples: an analog four pole voltage controlled filter (the first version of this module)
  • Mutable Instruments, Blinds: four channel four quadrant multiplier (which I could use as a VCA)
  • QU-bit, Nebulae V2: granular synthesis processor and open source DSP programming platform, with an extensive library of additional instruments
  • Intellijel, Planar II Vector Joystick: joystick
  • Intellijel, Random Noise Tools (1U): a collection of useful functions (noise generator, sample and hold, slew, etc) in a 1U rack space
  • Expert Sleepers, FH-2: programmable MIDI interface with a nice set of tools

Boxes started to show up at my door!

This second set of purchases for Stage #1 rounded up a nice initial rack. I got another (mono) signal chain (the Plaits oscillator and Ripples filter), a module I could use as a VCA (Blinds), an immensely useful and fun granular processor (Nebulae II), a precision joystick (Planar II), and a very programmable (and expandable) MIDI to CV interface (FH-2).

I immediately liked the Nebulae II, I could (and did) spend hours just having fun with it, and it was also obvious that pairing it with the Planar II joystick provided very precise two dimensional control space of selected parameters. The Nebulae and Planar have been tied together ever since.

The Nebulae II is actually a general purpose system and fully expandable (its core is a Raspberry Pi 3!). Eventually I installed a better, customized firmware image of the underlying software. Details can be found in the following links:

Stage #2

This second round of purchases rounded up the initial set of modules. I got much needed VCAs (the four quadrant multiplier was not that useful as a VCA), expanded the initial Stages envelope generator to two units chained together (12 stages), expanded the FH-2 MIDI interface to more output channels (24 total), and added a simple way to connect the synthesizer to my external audio interfaces so that the modular could talk to my computers.

I had initially wanted to buy the Expert Sleepers ES-8 or ES-9 which are USB computer audio interfaces, but they were impossible to find. Instead I bought two OctaLink passive interfaces as a multichannel analog connection point to a Motu audio interface (8 channels of input and output).

  • Expert Sleepers, FHX-8CV: two 8 channel CV expansion modules for the FH-2 MIDI interface
  • Mutable Instruments, Stages: another Stages, they can be chained to create arbitrary length envelopes, low frequency oscillators and many other things
  • Intellijel, Quad VCA: much needed VCA ("you can't have too many VCAs")
  • Intellijel, Dual VCA (1U): a small dual VCA that uses 1U rack space
  • Intellijel, OctaLink: 2 eight channel eurorack to ethernet cable expanders

The OctaLink story

The OctaLinks proved to be problematic and I spent quite some time debugging noise issues. This was complicated by several unrelated problems: the power supplies for the small fanless computers I was using were actually generating noise that percolated into the audio connections between the modular and the computer, there was an intermittent bad patch cable, and I also had problems due to old switches in the mixer I was using at the time (all items conspired together to make it quite hard to find out what was wrong).

The situation improved substantially when I lifted the ground of the computers's power supply. But that did not end persistent low level noise in the audio connections, which I eventually traced to non-zero resistance in the ground path of the OctaLink cables. The OctaLink uses the shield of the shielded ethernet cable as the "common ground" for all connections, and the supplied cable is just not good enough - as a counter-example the Doepfer A180-9 is very similar module that only offers 7 connections instead of 8, and uses the remaining wire as ground.

Jumpering a good cable between grounds on both ends of the ethernet cable got rid of the noise. So I searched and bought what I hoped would be a better shielded ethernet cable. This cable used an actual wire for the shield ground (outside of the 4 twisted pairs inside the shield). This solved the problem. I could actually measure the difference in resistance between the original and improved ethernet cables.

The FH-2 and controllers

The FH-2 is a very versatile MIDI interface that has two front panel USB MIDI connectors and one hardware MIDI port (that can be connected to an expansion panel with connectors). It can translate MIDI commands to control voltages, gates and triggers and can also generate LFO waveforms, envelopes and other outputs. Very configurable. Through its MIDI connection it can also connect to a PS4 controller so I bought one (this also proved to be quite difficult - as many other things I wanted they were nowhere to be found!). Once programmed I could have four additional analog outputs that follow its two joysticks, and as many buttons and triggers as I cared to tie to outputs of the FH-2. By the way, it has to be a PS4 controller, I had a couple of old PS3 controllers but those did not work.

The PS4 controller was less useful than anticipated because of the "return to center" springs of the joysticks. That made it impossible to control any parameters that would have required that I keep my hand on the controller at all times.

Much later I dissasembled the controller and removed the centering springs so I could use the joysticks and leave them alone without them returning automatically to the center position. Nothing is ever simple. After I did that, the joysticks were not that useful for the opposite reason: they had almost no friction and would not stay in position. Eventually I replaced the cap and button assembly with a 3D printed parts printed with TPU flexible plastic. It took several tries, but eventually the cap provided enough friction with the body of the controller to make the joystick stay in place when left alone, and move smoothly when operated.

Stage #3

I started using VCV Rack on one of my small computers. VCV Rack is a very complete software Eurorack modular synth. I started looking at some Eurorack modules that had been ported from hardware to software (in particular the "Audible Instruments" collection, based on the Mutable Instruments modules). Some of them sounded really interesting so I decided to get the hardware version.

I could see how more compact versions of some of the modules I was interested in would use less rack space (at the cost of smaller knobs, so less finger friendly). Actually, one of the modules I became interested in had been deprecated in 2017 (the Mutable Instruments Clouds) and was no longer in production. But because all Mutable Instruments modules were released as open, free software projects (something which I quite liked and biased my choices when selecting what to buy), many companies were offering clones or improvements on the original design, including expanded firmware images with additional modes of operation. Of the available clones I got the uBurst. And I thought a good companion would be a clone of the original Rings Mutable Instruments module.

These were the Stage #3 module additions:

  • After Later Audio uBurst: Clouds clone in a small rack space with expanded firmware (Parasites)
  • After Later Audio nRings: Rings clone in a small rack space
  • After Later Audio 3 to 1 mixer: simple mixer

I really liked the combination of Rings feeding into Clouds (it was only much later that I found that "Rings into Clouds" is a cliche that everyone uses... oh well...). Rings implements (amongst other things) plucked strings using the Karplus-Strong algorithm. In that mode it can create a stereo field where four strings can be excited (and "ring") at the same time. Feeding the stereo outputs to uBurst (Clouds) can multiply them, sample them and generally process them into very interesting textures. I almost immediately coupled nRings and uBurst with the Intellijel Noise Tools 1U module - its random triggers coupled with the sample and hold unit gave me a very nice and simple to control trigger source for the plucked strings, and drive the pitch of both nRings and uBurst (the connections between these three units kept evolving over time and it is one of the "workflows" I routinely use).

Stage #4

Printing the joiner plate

It was obvious now that my initial Intellijel case was getting full and I still had some modules I was interested in adding to the synth. I started looking at case options for expanding it. Again, it was not easy to find something I liked due to availability. I finally bought a 3U 104HP Tall Dog skiff enclosure with an external power supply. I spent some time designing and 3D printing custom joiner plates to mechanically connect both cases as a single unit.

The Intellijel case has slots at the bottom and the top to chain them together with metal plates that they sell. Starting from a photograph of the metal plate I found online I designed a 3d-printed joiner that worked very well, it clicks into the Intellijel case and is screwed to the bottom of the Tall Dog skiff, replacing a small metal plate in it. I had a 3 x 3U 104HP system (plus the Intellijel 1U space).

The next round of modules filled more processing and signal generation needs in the signal chain.

  • After Later Audio, uT_u (Temps Utile): programmable clock and trigger generator
  • After Later Audio, uTides v2: a clone of the Mutable Instruments Tides
  • After Later Audio, PachinkoMarbles module
  • After Later Audio, Atom: clone of the Mutable Instruments Elements module
  • Grayscale, Microcell: clone of the Mutable Instruments Clouds but with extended input/output, modulation capabilities and extended firmware (a custom port of the SuperParasites firmware which combines both Parasites and Kammerl Beat Repeat functionality into 8 separate modes)
  • SSF, Stereo Dipole: dual four pole filter, highly customizable
  • Mutable Instruments, Veils v2: quad VCA with offset

I had been playing with Marbles, Atom and others in VCV Rack so I knew they would be useful. uTides and Pachinko are interesting modulation sources (specially Pachinko). Atom turned out to be not as good as I expected, it is a modular physical modeling synthesis module with a multiple resonator section and three independent excitation sources (bowed, breath and strike). The Stereo Dipole dual filter turned out to be very good, and more general purpose than the QPASS filter I already had, which is (I think) very idiosyncratic and with a peculiar sonic character - and also a bit noisy when running at high values of Q. Finally the Microcell was a nicely expanded version of the original Clouds, with extended firmware and modulation options that exposed the multi-purpose input of the original Clouds. I would dare say that you can't have too many clouds in your rack. Of course another quad VCA and finally a versatile multiple-output clock generator.

A subsequent purchase finished up Stage #4.

The Ornament and Crime module nicely complements the Temps Utile clock generator. Both are open source and have a wealth of options. The 1U high O_c used up 1U rack space of which I still had quite a bit left (Intellijel 1U modules were particularly hard to find).

The Applesauce Modular at Stage #4, ready to go

And I ran out of rack space again. I considered several extension case options but again opted for a Tall Dog 104HP 3U skiff (this time I bought the unpowered version as the powered one was no longer available). A bit more OpenSCAD work and I 3D printed two additional joiner plates that allowed us to couple the new skiff to the lower part of the Intellijel case. Being unpowered I temporarily borrowed power from the Intellijel case, but eventually bought an additional power supply directly from Tall Dog.

One more rack space with the XVI fader bank

This additional rack space allowed us to add some more modules.

This proved useful as a generic analog control source (as opposed of the quantized outputs of the FH-2 USB MIDI interface module). I programmed this into a generic controller for levels, modulation strength and other purposes. I considered the Sweet 16 from Tesseract, but the XVI won because of the longer throw faders (at the cost of more rack space). A combination of both would have been perfect, the Sweet 16 has CV inputs that can be controlled from the faders (but the faders are shorter, tradeoffs)...

Stage #5

Another expansion of the modular. Some additional modules were added:

Choosing a sample player was difficult. There were several modules that were good candidates, but ultimately a low tech solution was selected, the Nutella Tsunami, which is an Eurorack adaptation of a bare board (the Tsunami) which has 8 independent outputs, 16 trigger inputs and high polyphony. It is "programmed" by a control file in the SC card that you inser that holds the samples (see information here), and as such it is not something you can change in realtime or through a graphical interface. But as I like programming that was not an issue. There are some maddening limitations in what it can do which I only discovered once I started to use it.

The board also has a serial interface with an associated control protocol which could be used to create a more useful interface, but that would be a big project on its own.


I decided to add an analog crosspoint switch that would help for realtime performance of the system. It looked like the best option would be the Alyseum Matrix II, but it was again impossible to find. I ended up ordering directly from the company (based in Belgium) as soon as they had it in stock - I was checking daily. It arrived fine.

  • Alyseum, Matrix II, 16x16 crosspoint switch

This was a good addition that allows me to "repatch" the system instantaneously, something which is great if you are using the modular for realtime pieces. Regretfully the system is in practice limited to a 15x15 full matrix, or 15 inputs and 15 outputs to be precise, I could really have used a full 16x16 system as most of my workflow is stereo.

Why 15 outputs only?. While the latest version of the manual (for firmware 0.3) is clear on the fact that you can only use 15 of the 16 inputs, it does not really say much about the outputs and how they might be limited. It states that you can connect to all 16 outputs, but you can only do that if ALL of the inputs are connected somewhere. If any input is not connected, you are not allowed to connect to output #16. In my workflow I connect some of the inputs to several outputs at the same time (perfectly legal use of the matrix), which means I will have inputs that are not connected anywhere. Which means my matrix has now only 15 outputs, a big limitation as my workflows are stereo. I REALLY could use all 16 outputs. Caveat emptor.

You cannot have too many clouds

I think that the well known aforism in modular synths that "you cannot have too many VCAs" also applies to Clouds.

I had a little bit of space left in the lower right hand corner of my rack, and before I knew there was an announcement of a new version of Clouds coming up (Beads). This was a long time coming...

After pre-ordering and patiently waiting for it to be available and ship I have now even less space in my racks. Well worth the wait. Much better audio quality, much nicer routing and control options than the original Clouds (to be expected of course). Very well tuned scaling of the different knobs.

(C)1993-2021 Fernando Lopez-Lezcano.
All Rights Reserved.