Software
I have contributed to the development and maintenance of dozens of best-selling synthesizers and guitar effects.
While virtual analog circuit models are my main area of expertise, I do feel comfortable dealing with all sorts of music DSP, including bandlimited oscillators, wavetable and granular synthesis, FIR and IIR filters, delay-based and modulation effects, dynamic processors, distortions, and waveshapers.
Here are some of the companies I work with and products I helped create.
Arturia
I have been employed at Arturia from April 2015 to December 2017 and our collaboration is still ongoing.
They have been creating software synthesizers since early 2000s, and indeed today they offer an extremely comprehensive and renowned collection of virtual instruments. Also, the company recently entered the software effects market with faithful recreations of classic devices.
These are the most important products I have worked on for Arturia.
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Acid V (2023)
There is certainly no shortage of plugins emulating this corrosive bassline machine, as Arturia calls it, yet matching the sound and behavior of the original is not as simple as it might seem.
The resulting plugin is complemented with a bunch of useful additions, and it especially contains an evolved sequencer that makes it more enjoyable to play.
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Korg MS-20 V (2022)
Working on this new plugin that convincingly replicates the wild screaming nature of such a legendary synthesizer was one of the thoughest challenges in my career so far.
If you haven't tried it yet, I'm only anticipating you that I'm really proud of the outcome.
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CS-80 V (2022)
This new version of one of the classic V Collection plugins came with a new sound engine that is much more powerful and faithful to the character of the original device.
Given how rare, expensive, fragile, and cumbersome these late ‘70s monsters are, preferring this plugin to them is a no brainer IMHO.
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Jup-8 V (2020)
The fourth edition of this classic plugin had its sound engine completely reworked and the improvements are noticeable according to the press.
It now stands much closer to the original instrument sound-wise while largely exceeding it in functionality.
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OP-Xa V (2020)
In mid 2020 Arturia released their digital incarnation of this fat analog heavyweight from the ‘80s out of the blue, that is not as part of a new version of their V collection.
Needless to say, if it's in this list it means I helped them pull this one out as well.
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Synthi V (2019)
My first collaboration as a freelancer on a big plugin recreating one of the most iconic and venerated vintage classic synths in digital form.
Indeed, the original instrument has been extensively used by artists such as Pink Floyd, Brian Eno, Robert Fripp, and Jean-Michel Jarre, thus largely contributing to the imaginary of synth sound.
As usual with Arturia recreations, the digital version adds a wealth of extra features (e.g., polyphony, sample&hold, extra modulations) improving its usability and versatility.
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Buchla Easel V (2017)
The sound engine hosts a full, high-quality, component-level model of the Buchla Music Easel synthesizer, with extra added features (e.g., polyphony, MIDI sync, extra modulations).
I took the lead of the DSP development and performed all of the circuit modeling.
The plugin has instantly turned into a best seller, won the MIPA 2018 award as part of V Collection 6, and has received very positive reviews.
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Filter MINI and Mini V filter (2016)
It is no secret that the filter algorithms in Filter MINI and recent Mini V are based on my research.
Especially since Filter MINI was released as a free Christmas gift for a couple of weeks in late 2016 (then called Minifilter V) – a circumstance that was sufficiently covered by the specialized press – I got an overwhelming amount of feedback, and almost unanimously positive.
Filter MINI has been such a success in terms of downloads that Arturia server admins still remember those give-away days with horror.
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Spring 636 (2020)
This plugin is a tribute to a legendary and rare spring reverb unit from the ‘60s.
It contains a full component-level simulation of the entire circuitry of the original device, which relies on germanium transistor technology for buffering and amplification, as well as on an incandescent lamp for compression. Plus, you get a wealth of extra features, as with all Arturia software products.
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Memory Brigade — now Delay Brigade (2019)
This is the digital reincarnation of one of the best known BBD delay pedals in music history, and probably one of the most beloved musical toys in general.
It captures the dark/lo-fi character of the original and adds new capabilities (e.g., stereo, MIDI sync, ping-pong mode, mid/side processing) that make it more convenient for today's musicians and producers.
Neural DSP Technologies
I first visited Neural DSP's offices in Helsinki in January 2018 and shortly after we started an intense collaboration.
I believe they have the finest guitar/bass amp and pedal emulations on the market and I am proud to have contributed to their development.
Here's how I helped.
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Plugins (since 2018)
These plugins are particularly praised not only for their ultra-realistic sound and feel, but also for the large variety of great tones and the easiness in obtaining them.
Each plugin is conceived as a suite of carefully and tastefully picked effect pedals, amp heads, cabinets, etc. that easily lead to the exploration of a specific sonic palette when used together.
I worked with the Neural team on component-level models of some preamps and power amps, as well as distortions and other pedals.
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Quad Cortex (2021)
Marketed as the most powerful floor modeler on the planet, Neural DSP's Quad Cortex is a neatly designed embedded system that combines the power and versatility of a modern day computer with the ease of use of a multi-effect pedal.
The device ships with an impressive and ever-expanding list of modeled devices and other effects and also features a new black-box device modeling system.
I developed models of several distortion and other kinds of pedals, as well as other effects.
Behringer
For good or bad, almost everyone who has ever played an electric instrument, whether a stringed one or a synth, knows Behringer.
Having the opportunity to work with such a big and famous company is at the same time a big challenge and a great recognition. I guess not many colleagues can boast such sort of collaboration.
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Vintage (2024)
Orastron, the company I founded and lead, teamed up with Behringer to develop the synthesis engine of their first ever plugin.
This marks their actual entry into the music software industry, and trust me, this is just the beginning. 😉
Darkglass Electronics
Darkglass makes some of the most innovative and exquisitely high quality bass gear available as of today.
We knew each other since 2018 and we started working together in 2020.
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Exponent 500 (2022)
This is a modern, compact, and feature-packed amp head + multi-effect device.
I contributed a bunch of effects (distortions, modulations, noise gate) and the tuner algorithm.
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Element (2020)
Darkglass Element is a double headphone amplifier with Bluetooth, equalizer, tuner, guitar/bass amplifier/cabinet simulator, USB sound card, and more, in a small guitar pedal enclosure.
I contributed amplifier models and the tuner algorithm.
Elk
I first met the guys in late 2017 and started to cooperate with them a few weeks later.
Elk (formerly known as MIND Music Labs) is the company behind the homonymous software for playing live over the internet and the Elk Audio OS, which is the first ultra-low latency Linux-based OS in the world.
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Atlante (2018, 2019)
This is the prototype of an original freeze/sostenuto effect, first developed as a plugin and then “ported to the physical world” using the Elk/Pi platform.
This effect is based on a new algorithm I came up with to help Elk showcase their technology at NAMM 2018, and which eventually became the subject of a scientific publication later that year. At that trade show they also got a nomination by the MIDI Manufacturers Association for having one of the best new products.
When Elk was about to launch its Raspberry Pi-based development kit in 2019, I was involved in the closed beta and we decided to make a physical prototype around the algorithm. They supplied the development kit and I took charge of everything else in this project.
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Error concealment and resampling for Aloha — now simply Elk (2020, 2023)
The Elk software allows for real-time remote music creation and performance. It basically lets people to play music together live over the Internet even if they're miles apart.
Packet loss can happen at any time on standard networks and especially in low latency application contexts. In that case Elk replaces the missing audio by using a high-quality zero-latency error concealment algorithm I have developed.
Furthermore, since the system works with heterogenous and distributed equipment, audio needs to resampled in a way, with as little latency as possible given the context. Guess who helped them with that.
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Sushi internal plugins (2023)
Sushi is the headless DAW at the core of audio and midi processing in the Elk Audio OS.
It comes with a suite of production-level plugins based the algorithms I have developed for the Orastron Brickworks DSP library.
Clack.DIGITAL
In 2024 I decided it was time to step into the music software market directly, and so the Clack.DIGITAL brand was born.
Our mission is to create instruments and effects which combine world-class DSP with a smooth and delightful user experience, while treating users with respect.
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Just Pedals (2024)
Our first product is a no-nonsense iOS virtual pedalboard app for iPad and iPhone.
It comes with 16 essential virtual effect pedals and the DSP is based on the Orastron Brickworks DSP library.
Faselunare
Faselunare is a small maker of digital hardware for electronic music based in Turin, Italy.
I probably met Francesco from Faselunare probably around 2018, as he's also the founder of the SoundMiT trade show, but only collaborated with them in 2023.
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Vega firmware v2.0 (2023)
The Vega is a compact 4-voice eurorack drum module capable of generating multiple sounds at once. It combines a synthesis engine and a sampler.
In the second major firmware release I helped them redesign the synthesis algorithms based on the Orastron Brickworks DSP library.
Orastron
This is my own company, and yes, I've worked for us as well. 🙂
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Brickworks (2023-present)
Brickworks is a library of fundamental and reusable DSP algorithms which I developed to avoid reinventing the wheel every time.
The API and implementation designs are rather original and are based on years of research and experience (as you can see). The quality, performance, and portability of this library are unmatched on the market as far as I know.
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A-SID (2022)
I decided to celebrate the 40th anniversary of the debut in 1982 of the Commodore 64 by giving birth to a lysergic and eccetric product that allows to use the original machine as a wah effect without hardware modifications.
Not only we turned this crazy idea into reality, but also created a VST3 plugin and a web demo that emulate the experience on modern devices.
This is by far the most varied and delirious project I've ever worked on.
Research
I am involved in scientific activities since the beginning of my doctoral studies in 2011. Today I cooperate with several universities and publish new results as an independent researcher.
This allowed me to acquire deep and extensive knowledge in the field, which I use to continuously refine my work methods. Also, it forces me to stay up-to-date with the latest developments and to keep an open mind for innovation.
Here is a full list of my scientific publications with related extras.
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Virtual Analog Modeling of Nonlinear Musical Circuits
Doctoral dissertation, Aalto University, Espoo, Finland, November 2014.
Concise, down-to-earth, yet scientifically rigorous introduction to white-box VA modeling.
It touches on traditional circuit simulation and MNA, state-space methods, WDFs, and ZDF techniques, then details practical applications of those principles in my previous research.
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Generalized Moog Ladder Filter: Part I–Linear Analysis and Parameterization
S. D’Angelo and V. Välimäki, IEEE/ACM Trans. Audio, Speech, and Lang. Process., vol. 22, no. 12, pp. 1825–1832, December 2014. DOI: 10.1109/TASLP.2014.2352495.
In-depth linear response analysis of the ladder filter generalized to any number of stages.
Various alternative parameterization strategies are considered, and a low cost linear digital model that correctly reproduces the frequency response is proposed.
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Generalized Moog Ladder Filter: Part II–Explicit Nonlinear Model through a Novel Delay-Free Loop Implementation Method
S. D’Angelo and V. Välimäki, IEEE/ACM Trans. Audio, Speech, and Lang. Process., vol. 22, no. 12, pp. 1873–1883, December 2014. DOI: 10.1109/TASLP.2014.2352556.
A new ZDF technique is proposed that is fully non-iterative, perfectly accounts for linear behavior, requires minimal topology modifications and no transformation of nonlinearities.
It is then applied to discretize a large-signal model of the ladder filter generalized to any number of stages, leading to a lightweight and high-accuracy implementation with strong stability guarantees.
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A Digital Model of the Buchla Lowpass-Gate
J. Parker and S. D’Angelo, in Proc. 16th Intl. Conf. Digital Audio Effects (DAFx-13), pp. 278–285, Maynooth, Ireland, September 2013.
Simple and efficient implementation of both the control and audio paths, as well as their peculiar optocoupler-based interconnection.
Dynamic and nonlinear effects are accurately reproduced and stability is preserved.
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Emulation of Operational Amplifiers and Diodes in Audio Distortion Circuits
R. C. D. de Paiva, S. D’Angelo, J. Pakarinen, and V. Välimäki, IEEE Trans. Circ. Systems–II: Express Briefs, vol. 59, no. 10, pp. 688–692, October 2012. DOI: 10.1109/TCSII.2012.2213358.
Simple WD opamp model, and explicit WD models of single and antiparallel diodes based on the Lambert W function.
They are usd to simulate two common guitar distortion circuits with high accuracy and minimal CPU usage.
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New Family of Wave-Digital Triode Models
S. D’Angelo, J. Pakarinen, and V. Välimäki, IEEE Trans. Audio, Speech, and Lang. Process., vol. 21, no. 2, pp. 313–321, February 2013. DOI: 10.1109/TASL.2012.2224340.
Two high-accuracy and delay-free vacuum tube triode models for use in WDFs, based on a mixed physical-interpolative approach.
Tests show lower CPU usage and richer harmonic response than previous models. The algorithm is flexible enough to let the interpolation scheme be easily modified.
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Arbitrary-Order IIR Antiderivative Antialiasing
P. P. La Pastina, S. D’Angelo, and L. Gabrielli, in Proc. 24th Intl. Conf. Digital Audio Effects (DAFx20in21), Vienna, Austria, September 2021.
Antiderivative antialiasing is extended to use arbitrary IIR filters for the virtual downsampling by employing partial fraction expansion and analytical or numerical integration.
Formulas are given for single and multiple, real and complex conjugate poles.
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Antiderivative Antialiasing for Arbitrary Waveform Generation
L. Gabrielli, S. D'Angelo, P. P. La Pastina, and S. Squartini, IEEE/ACM Trans. Audio, Speech, and Lang. Process., vol. 30, pp. 2743–2753, August 2022. DOI: 10.1109/TASLP.2022.3198007.
Antiderivative antialiasing with virtual IIR downsampling is applied to the generation of arbitrary piecewise linear waveforms.
The effectiveness of such an approach is only bounded by the chosen antialiasing filter characteristics.
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Fast Approximation of the Lambert W Function for Virtual Analog Modelling
S. D’Angelo, L. Gabrielli, and L. Turchet, in Proc. 22nd Intl. Conf. Digital Audio Effects (DAFx-19), Birmingham, UK, September 2019.
The paper suggests reformulating expressions containing the Lambert W function in terms of the Wright Omega function and provides very fast approximations.
Two application examples show the usefulness of the proposed method.
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Optimal Integer Order Approximation of Fractional Order Filters
P. P. La Pastina and S. D’Angelo, in Proc. 24th Intl. Conf. Digital Audio Effects (DAFx20in21), Vienna, Austria, September 2021.
A criterion and simple formulas are found to optimally place poles and zeros when approximating fractional order lowpass filters with integer order filters.
The result can be easily extended to other fractional order filter types.
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A General Antialiasing Method for Sine Hard Sync
P. P. La Pastina and S. D’Angelo, in Proc. 25th Intl. Conf. Digital Audio Effects (DAFx20in22), Vienna, Austria, September 2022.
Antialiasing of hard-synced sine waves is more complicated than classical geometric waveforms since it introduces discontinuities in the signal and in an infinite number of its derivatives.
A technique based on convolution with wide classes of FIR kernels is developed and is proven to be largely more effective and cost efficient than the best known method.
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A Quadric Surface Model of Vacuum Tubes for Virtual Analog Applications
R. Giampiccolo, S. D’Angelo, A. Bernardini, and A. Sarti, in Proc. 26th Intl. Conf. Digital Audio Effects (DAFx-23), pp. 296–303, Copenhagen, Denmark, September 2023.
Simple yet precise triode model characterized by only 3 parameters that can be easily extracted from datasheets.
It can lead to non-iterative circuit models only requiring elementary mathematical functions and thus to highly-efficient implementations.
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Efficient Signal Extrapolation by Granulation and Convolution with Velvet Noise
S. D’Angelo and L. Gabrielli, in Proc. 21st Intl. Conf. Digital Audio Effects (DAFx-18), pp. 107–112, Aveiro, Portugal, September 2018.
A cheap and tonally-transparent time-domain method to extend the duration of any audio signal without sounding static.
Developed to help the guys at Elk demonstrate their ELK MusicOS at NAMM 2018.
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Ciaramella: A Synchronous Data Flow Programming Language For Audio DSP
P. Marrone, S. D’Angelo, F. Fontana, G. Costagliola, and G. Puppis, Sound and Music Computing 2022 (SMC-22), Saint-Étienne, France, June 2022.
This paper introduces the Ciaramella DSP language and its compiler named Zampogna in their first development iteration.
The peculiar properties of the language and compiler allow for easy expression and automatic static scheduling of wave digital filters.
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Introducing stateful conditional branching in Ciaramella
P. Marrone, S. D’Angelo, and F. Fontana, Sound and Music Computing 2023 (SMC-23), Stockholm, Sweden, June 2023.
Stateful conditional branching is added to the HSDF formalism via conditionally-updating actors.
Corresponding constructs are added to the Ciaramella language without compromising its modular declarative paradigm.
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PIPES: A Networked Rapid Development Protocol for Sound Applications
P. Marrone, S. D’Angelo, and F. Fontana in Proc. 27th Intl. Conf. Digital Audio Effects (DAFx24), Guildford, UK, September 2024.
An experimental protocol designed to streamline audio software development and deployment is proposed.
In particular, it allows for coding, compilation, and hot reloading, each on a potentially different machine.
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Antiderivative Antialiasing with Frequency Compensation for Stateful Systems
P. P. La Pastina and S. D’Angelo, in Proc. 25th Intl. Conf. Digital Audio Effects (DAFx20in22), Vienna, Austria, September 2022.
This paper investigates the use of frequency response compensation filters added in series to antiderivative antialiasing blocks that attenuate aliasing in static nonlinearites.
It is shown that, when using simple pole IIR kernels, such filters are stable. Therefore, it becomes possible to use such devices in recursive stateful systems without affecting their frequency response and stability.
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Analysis and Emulation of Early Digitally-Controlled Oscillators Based on the Walsh-Hadamard Transform
L. Gabrielli, S. D'Angelo, and L. Turchet, in Proc. 22nd Intl. Conf. Digital Audio Effects (DAFx-19), Birmingham, UK, September 2019.
Theory of “staircase-style” waveforms and analysis of two historical synth DCOs.
Virtual analog emulation methods are also explored.
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Wave-Digital Polarity and Current Inverters and Their Application to Virtual Analog Audio Processing
S. D’Angelo and V. Välimäki, in Proc. Intl. Conf. Acoustics, Speech, and Signal Process. (ICASSP 2012), pp. 469–472, Kyoto, Japan, March 2012. DOI: 10.1109/ICASSP.2012.6287918.
Clever yet fundamental (IMHO) addition to basic WDFs, where two new adaptors allow to easily interconnect subnetworks using different polarity and sign conventions.
They are trivial to implement, fully compatible with existing WD structures, perfect to avoid remodeling asymmetrical subnetworks, and proven to never cause stability issues.
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Lightweight Virtual Analog Modeling
S. D’Angelo, in Proc. 22nd Colloquium on Music Informatics (XXII CIM), pp. 59–63, Udine, Italy, November 2018.
Essential references and practical advices to help DSP programmers implement efficient real-time circuit simulation algorithms.
This was an invited paper to a national conference that has a long and important tradition.
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An Improved Model of the Moog Ladder Filter
S. D’Angelo and V. Välimäki, in Proc. Intl. Conf. Acoustics, Speech, and Signal Process. (ICASSP 2013), pp. 729–733, Vancovuer, Canada, May 2013. DOI: 10.1109/ICASSP.2013.6637744.
Detailed derivation of a large-signal model of the ladder filter and development of a digital model that outperforms previous attempts in nonlinear behavior.
Largely made obsolete by more recent research I have conducted.
Bio
I was born in 1987 and have always been interested in computers and music. I studied classical piano as child, electric bass in my high school years, and electronic music production in 2018. I played hundreds of gigs.
In 2008 and 2010 I got B.Sc. and M.Sc. degrees in computer engineering from Politecnico di Torino, Turin, Italy. In the meanwhile I got involved in free/open source music software projects, started one of my own called NASPRO, and participated to two editions of the Google Summer of Code program as a mentor. Also, in 2008 I was an intern at Digitec, an electronic engineering company, developing embedded software, and in 2010/2011 I worked at ISMB, a research institute, on a big EU-funded project.
Then I started my doctoral studies, which led to me getting the D.Sc. (Tech.) degree in signal processing and acoustics from the Aalto University, Espoo, Finland, in 2014.
From April 2015 to December 2017 I have been leading DSP research and development at Arturia in Grenoble, France.
Since March 2018 I work as a freelancer from Italy. I am today:
- member of the Association of Engineers of the Province of Salerno (sez. A, n. 7093);
- recognized as an individual expert by the Ministry of Higher Education, Research and Innovation of the French Republic for research tax credit (a.k.a. CIR, crédit d'impôt recherche) for years 2018 — 2023;
- credited with the CERTing certification in physical-mathematical modeling from the Italian Agency for the Certification of Engineering Skills.
In January 2021 I founded Orastron to complement my freelancing activity. In 2024 I launched the Clack.DIGITAL brand.
