Tag Archives: Kilpatrick Phenol

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.

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