I have contributed to the development and maintainance 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.
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.
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.
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 Colleection 6, and has received very positive reviews.
Minifilter V and Mini V filter (2016)
It is no secret that the filter algorithms in Minifilter V and recent Mini V are based on my research.
Especially since Minifilter V was released as a free Christmas gift for a couple of weeks in late 2016 – a circumstance that was sufficiently covered by the specialized press – I got an overwhelming amount of feedback, and almost unanimously positive.
Minifilter V has been such a success in terms of downloads that Arturia server admins still remember those give-away days with horror.
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.
Memory 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 todays' musicians and producers.
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 startup behind the Elk Audio OS, the first ultra-low latency Linux-based OS in the world, and the SENSUS Smart Guitar.
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.
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.
Doctoral disseration, 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.
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.
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 trasformation 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.
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.
S. D’Angelo, L. Gabrielli, and L. Turchet, accepted to the 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.
Analysis and Emulation of Early Digitally-Controlled Oscillators Based on the Walsh-Hadamard Transform
L. Gabrielli, S. D'Angelo, and L. Turchet, accepted to the 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.
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.
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.
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.
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.
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.
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 outpeforms previous attempts in nonlinear behavior.
Largely made obsolete by more recent research I have conducted.
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, 2019, and 2020;
- credited with the CERTing certification in physical-mathematical modeling from the Italian Agency for the Certification of Engineering Skills.