Tag Archives: Modular Synthesizer

The Difference Between Modular and Semi-Modular Synthesizers

The Kilpatrick Audio Phenol is a stand alone modular synthesizer, not a semi-modular synthesizer.
The Kilpatrick Audio Phenol is a stand alone modular synthesizer, not a semi-modular synthesizer.

There has been some confusion in the last year with regards to the difference between modular and semi-modular. Some people for example have been calling the Kilpatrick Phenol Semi-Modular. This however is not accurate, the Phenol is in fact a standalone modular synthesizer.

The difference between semi-modular and modular is that semi-modular has a hard-wired signal path that can be altered through patching, and fully modular instruments on the other hand requires patching. Modulars do not need separate units can be replaced. This is why the EMS Synthi and the Fenix are considered fully modular instruments. Semi-modular instruments of course are the Arp 2600, Korg MS-20, and more recently the Moog Mother-32.

The extent one can patch with a semi-modular synthesizers can vary greatly. The MS-20 for example lacks pre-filter/pre-mixer outputs for its oscillators. While the Arp 2600 allows for a great degree of patching between the various functions without such barriers.  The Moog Mother-32 adds a feature in that it can be hooked directly into a modular system.  The Buchla 208 was really what pushed out this concept.  These instruments can even be experimental, many of the Ciat-Lonbarde instruments are also semi-modular, such as the Sidrax. These limitations though often allow for some benefits, specifically the ability to approach the instrument without patching.  This can be helpful for those just learning synthesis to ease into modular functionality.

Modular synthesizers on the other hand come in two variety. One is modular systems, where you have cases or cabinets with modules you place modules or panels in. When you think of Moog, Buchla, and Eurorack, you are looking at a modular system.  This is a common standard where functional modules can be taken out and added. There is another category of modular though, which is the stand alone. EMS pushed forward with this concept with it’s Synthi pin matrix synths. The Fenix, and later the Phenol bring this concept to the realm of patch cable synthesizers.  These stand alone instruments do bring certain advantages, such as having all the necessary components for a voice, but still having all the advantages of signal path routing as a modular system. They also can bring increased portability, which can be an issue as modular systems grow in size.

Whether one is going with a fully modular synthesizer or a semi-modular, is often more about personal preference and budget.

Review: Kilpatrick Phenol

The Kilpatrick Audio Phenol
The Kilpatrick Audio Phenol

There has long been this promise of an inexpensive modular synthesizer that really never quite gets there. Something is always a little off. Modular synths are complicated beasts, and to really capture the spirit of modern modular movement, looking back is not really the right thing to do. It’s not so much about old vintage synthesizers, it is about bringing in new ideas that are now more common. There is also the additional problem of how to introduce budget conscious musicians to the concept of modular, yet provide them with a window of what is out there.

The Kilpatrick Phenol is taking a shot at this as it provides many of the features of modern modulars in a compact package for under $1000.

Features and Overview


There are a few things the Phenol did right that many manufacturers should pay attention too in the future. The first is the fact the analog oscillators have FM. Why in this day and age is this concept so foreign to those making all in one modular synths? I should note the FM on this synth is so beautiful, everything from bell tones to freak outs. It is an exponential FM circuit, from my experimentation with it, it can achieve some of the more melodic aspects of linear FM.


The much bigger deal is the envelopes, the envelopes are glorious and beautiful. While many manufacturers would be lazy and just throw in a standard ADSR, Kilpatrick went with what is known as a complex envelope. Which means much of the functionality of the device is found with the various options for the envelope. For those like myself who use modular systems extensively envelopes are not ADSR, they are often far more complicated, and the heart of any good modular system. They  take hints from serge and buchla. Make noise in fact literally exploded their business around such an envelope in Eurorack, called “Maths”. In this case Kilpatrick expanded significantly on a buchla style envelope. In fact I would argue for those who own 4U systems, the Kilpatrick Phenol is worth owning for the envelope alone. It is a multi-mode complex envelop with quantization. Yes, you can indeed bring the envelope into a mode to self cycle.  This provides a little bit more depth, as people who use complex envelopes already realize, they are not always going into a VCA, but often end up in a FM input on an oscillator or filter. This is where the envelopes in fact shine on the phenol. It should be noted, much of what this envelope is offering is new and unique. I have not seen some of these features in other envelopes I have had for modular synthesizer.  It is not very often innovation comes in on such a low cost synth, especially an entry level modular, yet here it is.

Truth be told, I think the tutorial covers the depth of the envelopes much better than myself.

Filters and VCA

The filters and VCA’s on the Kilpatrick are good, but a bit more cut and dry. This is one of those things where simplicity was the goal, and achieved. The filters once again have FM, which allows for some fun modulations. One is marked low pass, and the other high pass, even though the high pass one is more of a bandpass filter. These are not crazy resonant filters in the squelchy tb303 territory, they are a bit more refined, and do a more than adequate job for somebody looking to refine a patch using filtering. If you are looking to do searing acid, this is not quite the right filter for that. But it is more suitable for most other tasks a filter can handle.  It is not a self oscillating filter though, and that is kind of important to some.

The VCA’s are pretty simple VCA’s, and frankly, I am not going to dedicate that much ink to them. They do the job, and that is really all one needs to know with this unit.

LFO and Math

The LFO is fairly minimal on its own, especially in combination with some of the other functions. The random provides some standard S&H stepped voltages, and the sine is good for FM with the oscillators and filters.

The secret sauce for the Phenol though seems to be in divider and adder, which has the ability to really make things fun depending on what you plug into it, and where you are sending it, such as throwing it on PWM or an FM unit. The divider can also expand clock divisions for those with sequencers.  When combined with the adder, the results can be a little crazy.

Audio Input and Outputs

Another useful feature is to bring in regular signals into the signal chain. While this may seem a bit odd, this is incredibly useful, especially in live performance context.

The delay has been called a lo-fi echo, but I think it suits the overall module. The mixer also provides a left-right panning function.

Sorry, I did not test midi or the internal sequencer

Here is the part I will be honest with, I have not used the midi to CV converter, or the midi sequencer that comes with phenol. As somebody who uses primarily analog sequencers this functionality is not really something I see myself using much.

Live Performance

I have actually gave this the run through for live performance, and it sounded great in a small environment. The patch leaned more towards sci-fi as supposed to all out drone. Between the Envelopes and Random out I pulled off a beautiful semi-sequenced sound.

The delay ended up being more useful than I first thought, so while it is a bit lo-fi manipulating it can add an extra dimension to the sound. It was a wonderful added feature, which I would be disappointed if it was not there.

Size and Build

The build is solid, there are some choices which I think improve it in fact. Instead of gummy buttons, Kilpatrick went with smaller hard plastic ones. This is something that is greatly appreciated, as it prevents bad presses more than one realizes. Add to it the casing is entirely metal, which means it’s durable.

The one thing to note, is this is thin for a modular synthesizer, it is a little over an inch thick off of a table. I actually was able to put this into a mono laptop bag and was able to go to and from work to a show using mostly public transit. As somebody who lives in a city this is invaluable. While some musicians do appreciate larger setups, for those of us who live in cities, having something small counts a great deal. This is easily the most transit friendly modular that has ever been created. I would also have no issue with being able to fit this into a small carry on suitcase and taking it on a plane.

What Could Have Been Added

If somebody asked me what functions I would like on the phenol, it would likely be a waveshaper, which is an increasingly common function in modular synthesizers. This however is a minor gripe, since overall, the unit is fantastic, and a full voice with a great deal of functionality.  It is a great way to expand an existing serge system, or dive into banana format synthesizers. In terms of the missing ring modulation, oddly enough the adder does serve some of that purpose, and likewise so does the FM on the filters. I could have done without the midi and have had a few more modular features, but this is my own preference. Taking this is an entry level machine, appealing to those who are deep into midi and software, the USB and midi integration makes sense.

Addressing The Banana Synth Cost Issue

I should note, some have griped because Banana synths beyond this tend to be more expensive, but it should be noted 4U has been coming down more in price between more manufacturers coming into the serge space, and Kilpatrick’s own synth format. A typical serge panel would now cost close to $2000-$2500, where with STS it was $4000. Likewise the entry point for kilpatrick format is around $2000 for a small starter system, and per module it is not that much more than a typical eurorack module, and cheaper than many. It should be noted, many starter eurorack synths, are often in the same $2000 price range.

The cost problem with modular is getting off the ground, and this does that, and does that very well with a banana system.  At the same time this is a beautiful complete voice, one where somebody could just utilize this unit alone. For $850 that is a killer deal no matter the format.

Likewise if you want to use a eurorack synth with this, it is not that difficult. A Low-Gain built format jumbler is around $100. This has a ground out, this is really not that hard to integrate with a 1/8 inch jack system. It uses the same 1/v per octave standard as eurorack, so it is just a matter of using the format jumbler with the instructions on Kilpatrick Audio’s site.


This may very well be the best entry synth for modular synthesizers ever created. At $850, it is below the $1000 mark for synthesizers, and frankly, nothing is in it’s category for what it offers. This is a true desktop modular synthesizer panel for the masses.

Likewise by deviating from the east coast style, and going for more west coast functionality such as complex envelopes, and FM at several points, it distinguishes itself from other offerings, and opens up the world of complex synthesis. Likewise with this case this is a full modular and not a semi-modular offering like others in this price range.

This is a nice expansion for those of us who have serge, but is a wonderful starter modular synthesizer as well. It is also a great alternative for those wishing to leave their modular set-up at home, and are more interested in something they can take on the train or bus.

Above everything the Kilpatrick Phenol sounds fantastic. While no synth will ever be perfect, for what Phenol is, it comes very close for a small format modular synthesizer.

Beautiful Synthesizers: The Lunetta and CMOS

The Lunetta is an electronic instrument that uses primarily CMOS chips for gates, Boolean logic, and mathematical functions for sequenced sounds.  A Lunetta is basically a simple rhythmic modular musical computer that makes abstract sounds in sometimes unpredictable ways. It is a beautiful experimental synthesizer.

Lunettas are most typically DIY instruments, although there are a few small boutique manufacturers that sell them. ElectroLobotomy for example sells a few simple Lunetta synthesizers on Etsy.

The most beautiful part of a Lunetta is that one can make one for themselves and experiment with its functionality and layout. The guide for making a Lunetta can be found here: Intro to Lunetta CMOS Synths. The introduction goes into Stanley Lunetta’s concept, and provides an introductory guide for making them. Every Lunetta though is made a bit differently, as they often reflect the makers preferences.

While there are DIY Lunetta’s out there, some manufacturers have expanded the CMOS synth concept, and created some more advanced synthesizers that use CMOS functionality. Nonlinear circuits has done this more than any other manufacturer, and has integrated CMOS functionality into both 4U and eurorack modular synth formats. One of the most interesting CMOS modules that Nonlinear Circuits make is the cellular automata sequencer.


The Paradox of Choice and Eurorack Modular Systems

My Eurorack system these days is looking kind of sad. I cleared out and sold many modules to fund a Serge/Ian Fritz (4U) modular synthesizer system.  They were mostly modules which were no longer fitting my specific workflow, so they rarely were used. This was not for an active dislike of Eurorack modular synthesizers, I am not religious about format as some others are outside of my preference for smaller sized systems. I appreciate being able to gig with a modular system.

My Eurorack system is not quite it used to be...
My Eurorack system is not quite it used to be…

With that being said, I have pretty complicated feelings about Eurorack these days. It was my introduction to modular synthesis, and I do like it. It is a decent format that provides a great deal of functionality in a small format.  As somebody living in a city were smaller row homes and apartments are standard living, this is appreciated. While some people have massive systems, it’s largest advantage is one of size.  It is a modular system that one can fit complete systems in very small cases.

Overtime the format exploded in popularity because of it’s relatively low price, high functionality, and portability. The thing is with it’s expanding popularity, also came a flood of new manufacturers to the format. This has left me in a bit of a conundrum. With so many boutique manufacturers producing so many modules with varying degrees of functionality, it can lead to frustration.  This frustration is not coming from  lack of options, but one of too many.

There was a book not to long ago called the Paradox of Choice, it focused on how too many options often left people confused. For the longest time I did not quite understand really if the concept held water. After all choice is wonderful in most cases, and to few if they do not match your personal preferences can be frustrating.

However, during the last few years of Eurorack I began to understand the paradox. I get it completely get it now, and it is very true.

The reality is there are so many spins on oscillators, complex oscillators, filters, low pass gates, random, vca, envelopes, LFOs, chaos, etc from an ever growing list of manufacturers, it is pretty easy to get lost in it all.

There was one point where one could keep up with the new modules, and make a determination on whether the functionality was something one wanted. That is becoming much harder right now. While there are some that try to buy as many modules as possible with a Pokemon type obsession of “catching them all”, for those of us with limited budgets, or room, this is not a wise position.

While the paradox of choice creates a conundrum for those of us who have been around for some time, it also presents confusion for those who are very new. The were to get started question has become something in which there is no easy answer with Eurorack. A complex oscillator, low pass gate, and some modulation, sure, but which ones?  In some ways this is where the smaller complete systems by Make Noise, EoWave, and Pittsburgh Modular help. With that being said, these focused systems often limit exposure to the wider universe.

For those of us who have experience there is a bit of a knee jerk reaction to stick with our favorite manufacturers, which are often well established. This is sometimes done without giving new ones a real shot. After all there is modules outside of intellijel, cwejman, and make noise, but these are the most desired manufacturers. Part of this is quality, but part of it is familiarity and the issues that arise from the paradox of choice. We seek what we know we faced with an array of choices.

As it stands my Eurorack system is neglected at the moment. I am still keeping it though, largely because things can change. The largest reason I am keeping it around is because most DIY eurorack modules just take a few hours to complete. Right now for DIY synthesizers Eurorack modules is all I personally have the bandwidth for, and I would like to refresh my soldering skills before diving into DIY serge format. There may be finally something that will break through my own conundrum of the paradox of choice and offer something very compelling in Eurorack. I have no clue what it will be at this moment though. In fact the solution may be at the end of my soldering iron after all.

The Problem With Eurorack Modular Planning and Power Supplies

Make Noise recently brought up a topic on a board that is critically important, but not often thought about when going forward with Eurorack Modular synthesizer systems. There is a popular site called Modular Grid that offers people the ability to plan out modular synthesizer systems. One of the things which the site does not do a good job of incorporating though is the power consumption for modules or cases.  The problem that has crept up for Make Noise is people returning modules when that break when they have blown past the capacity of their power supply. They may plan a very elaborate system, but not have the sufficient power for the system itself. This is not a hard issue to run into, and there are reasons for it.

I am making this a very specific post because while I like to promote modular synths, they are something that does take a little special consideration. Some modules are very power hungry and it is easy to blow past the power consumption limits of ones modular power supply. The Metasonix modules for example are famous for using vacuum tubes, which are extremely power hungry. They were such an exception that Monorocket made special cases with significantly more resources for the power supply. In addition to the tube driven modules, there are also the modules that use modern digital processors. While these are not as power hungry as Metasonix modules, they do require more power than older analog modules. Enough of these more sophisticated modules, and you begin to run into problems.

The problem for Eurorack is sourced at it’s own history. When Eurorack started with Doepfer in the 1990s through the early 2000s, many of the cases were designed for modules which had a much lower power footprint. As Eurorack has changed over the years, the power consumption for more cutting edge modules forced the necessity for higher power ceilings as a result of higher consumption.  I will be honest, the newer modules with sophisticated functions and digital modules are what brought me into modular.  The “Buchla-lite” nature of eurorack is one of it’s greatest advantages considering it’s lower price point.

While I purchased many used modules starting off, I actually bought a new case because of these issues with power consumption. Even as far back as three years ago the problems of the older cases and power supplies were creeping up. While the older cases are a great way to get started with the less expensive and lower consumption modules, when one begins to feel they will be moving on to the next level, the case is generally the first thing people should replace if one bought used. In addition when getting custom made cases, it is highly recommended that there is enough power in the power supply for modern modules. Especially when one gets into the more power hungry modules that use digital technology.  It is one thing to go off of a low power consumption set up that uses mostly analog technology, it is another to be running a true modern modular hybrid system with the mostly recently produced modules. This is where getting a case with a power supply with a great deal of power headroom is very helpful.  Plan for your future modules, but keep in mind, you may need more power than you are anticipating. Because going over the limits of your power supply can have some very real costs for your modules.


An Overview of Getting Started with Synthesizers

I will be producing a number of posts with regards to getting started. This is a short overview of what I will be covering in the coming weeks.

DAW Software

Digital Audio Workstations (DAW) are software programs to produce and record music with your computer. DAW software also serve as a method of hosting software synthesizer plugins.

Software Synths and Effects

The most popular synthesizers used for recording these days tend to be software plugins. There are also plugins that can be used as audio effects. While many plugins are commercial products which can carry considerable cost, many are free. This is probably the best way to get started with learning synthesizers if one has a computer and is on a lean budget. In addition to desktop plugins, there is also the world of software synthesizers for mobile devices.

Keyboard Synthesizers

Synthesizers with keyboards have been a mainstay since the original minimoog. These often offer a relatively straightforward way to approach sound design. Previously the downside of these instruments, especially the analog ones, was the considerable cost involved. However, these days inexpensive analog synthesizers offer a great way to get started.

Modular Synthesizers

Modular synthesizers are a deep love of mine, and thus the name of the blog. These instruments offer a great deal of flexibility and frequently beautiful weirdness.  Modular synthesizers are at their heart analog computers designed for music. Getting started with modular though can be a rather confusing, even for those who do have familiarity with synthesizers. In addition to that I will provide some basic information on getting started with DIY instruments.

Beyond the Keyboard

Synthesizers are not just about keyboards. Theremins, sequencers, ribbons, and touch-plates are all valid ways to play a synthesizer without a keyboard. Many of these open up the instrument beyond the black and white approach keyboards offer.

And More

I will be covering everything from circuit bending, to exploring musical programming.  There is a great deal to cover, and these guides will explore both the very simple and straightforward starter guides to some more advanced topics for those wishing to dive deeper into synthesis.  This is all in addition to the normal blogging that will happen here.


The (Diminishing) Barriers of Entry to Modular Synthesizers: The Kilpatrick Phenol

The Kilpatrick Audio Phenol
The Kilpatrick Audio Phenol

The entry point to modular synthesizers used to be significant. The price points used were high enough that those who could afford the synthesizers was a limited audience.  Modular instruments were above all boutique instruments of enthusiasts and DIY builders.  Do not get me wrong there is nothing wrong with this, many of these early enthusiasts were composers such as Laurie Spiegel, who used them extensively in her early recordings. For women it was a way to compose and produce music without the institutional barriers of the conservatory.

While the barriers to synthesizers in general fell, modular synthesizers were a different story. In recent years the price barrier have been falling, the introduction of the Eurorack format by Doepfer in 1995 started opening up these instruments to a far broader audience.  In the last five years however the format exploded in popularity. The barrier to entry began to lower even more as a result as multiple manufacturers producing modules for the format.

In the last few days, Kilpatrick Audio, a Canadian company, announced the Phenol. While I will try to avoid endorsing products directly without trying them, the value of what they are offering is pretty impressive. It’s $850 retail price point (and I think that’s Canadian dollars) is lower than any comparable device . While the device is not a specific format, it does allow cross compatibility with other modular synths.  The added bonus is that it uses banana jacks, which are easily one of the most fun formats because the wires are stackable. The one thing that will never disapear with modulars though is the differences in jack formats. However, unlike the Korg MS-20 mini, the Kilpatrick Phenol synthesizer uses the standard voltages found in modular synthesizers.

The $1000 price barrier is a bit mythical in the realm of musical instruments. It is the real difference between enthusiasts and professionals, and a larger general audience and hobbyists.  While I can recommend several synthesizers to people, and I will on this blog, modular synthesizers which are close to my heart, tend to be out of reach to most people. It is hard to spend thousands of dollars on instruments with student loans, kids, and a mortgage. It is hard for teenagers to save up for modular instruments as well. The Phenol on the other hand could provide of an excellent entry point, one that can bring this type music technology into homes and schools.  I can only imagine bringing something like the Phenol into a Girl’s Rock or Women’s Rock program.

While I am not going to make a final verdict on the Kilpatrick Phenol until I play it myself, the effort to make a high quality affordable modular instrument is commendable. While I will be reviewing and discussing instruments that are expensive,  I am happy to start off this blog focusing on the announcement of a modular instrument that is accessible and more affordable.

When the Kickstarter opens up, I will be posting more about the Phenol.

Kilpatrick Phenol Specs:

  • Banana patch system with colour-coded jacks and voltages compatible with Kilpatrick Format and other modular systems
  • Two analog VCOs – triangle, ramp and pulse outputs
  • Two analog filters (low pass and high pass)
  • Two analog VCAs with level control
  • Two envelope generator / LFO combos with many unique features
  • An LFO with sine and random output
  • Internal MIDI to CV converter with DIN and USB MIDI interfaces
  • Compact mixer with digital delay with over 330ms of delay time
  • Digital pulse divider – divide MIDI clock or LFO output to create 4 musical time divisions
  • Buffered mixer / mult / inverter with level control
  • External audio input allows a stereo input to be patched like an oscillator signal – process your drum machine or other source through the system
  • Designed and made in Canada using high quality parts
  • Warranty: 1 year