Особливості реалізації нелінійних опорів в системах цифрової обробки сигналів

Показано, що імітація нелінійних елементів електронної техніки є надзвичайно важливою задачею в цифровій обробці сигналів при проектуванні діагностичної апаратури. До програм, які реалізують функції імітації, ставляться вимоги максимальної швидкодії обробки сигналів і високої стійкості отриманих результатів. Розглянутий підхід дозволяє успішно розв’язати поставлені завдання. При цьому пропонується застосовувати модифікований метод цифрових хвилевих фільтрів, які до цього часу використовувалися при моделюванні лінійних селективних схем.Показано, что иммитация нелинейных эментов электронной техники является чрезвычайно важной задачей цифровой обработки сигналов при проектировании диагностической аппаратуры. К программам, которые реализуют функции иммитации предьявляются требования максимальной скорости обработки сигналов и высокой устойчивости полученных результатов. Рассмотренный подход позволяет успешно решить поставленные задачи. При этом предлагается использовать модифицированный метод цифровых волновых фильтров, которые до этого времени использовались для моделирования линейных селективных схем.Non-linear electronics elements simulation is very important problem of digital signal processing in design of diagnostic apparatus. The software implementing these functions is required of maximum speed and high robustness of results. The method proposed in this article allows efficient solving of such tasks by using of modified wave digital filter method which was previously used in linear selective circuits modeling

Adversarial Guitar Amplifier Modelling With Unpaired Data

We propose an audio effects processing framework that learns to emulate a target electric guitar tone from a recording. We train a deep neural network using an adversarial approach, with the goal of transforming the timbre of a guitar, into the timbre of another guitar after audio effects processing has been applied, for example, by a guitar amplifier. The model training requires no paired data, and the resulting model emulates the target timbre well whilst being capable of real-time processing on a modern personal computer. To verify our approach we present two experiments, one which carries out unpaired training using paired data, allowing us to monitor training via objective metrics, and another that uses fully unpaired data, corresponding to a realistic scenario where a user wants to emulate a guitar timbre only using audio data from a recording. Our listening test results confirm that the models are perceptually convincing

Real-time digital simulation of guitar audio effects

Cieľom práce je oboznámiť sa so spôsobmi simulácie gitarových hudobných efektov, konkrétne s metódou stavového priestoru so statickou nelinearitou, v prostredí Matlab navrhnúť a odladiť algoritmus pre túto metódu a následne odsimulovať vybrané obvody. Odladené algoritmy následne implementovať v jazyku C++ a prispôsobiť na prácu v reálnom čase.The aim of this work is to study different methods for simulation guitar effects, especially SSMN method. Then write a correctly algorithm for this method in Matlab and apply it on different circuits. Correctly algotirhm implemented in the C++ and adapt to work in real-time.

Newton-Raphson Solution of Nonlinear Delay-Free Loop Filter Networks

For their numerical properties and speed of convergence, Newton-Raphson methods are frequently used to compute nonlinear audio electronic circuit models in the digital domain. These methods are traditionally employed regardless of preliminary considerations about their applicability, primarily because of a lack of flexible mathematical tools making the convergence analysis an easy task. We define the basin delimiter, a tool that can be applied to the case when the nonlinear circuit is modeled by a delay-free loop network. This tool is derived from a known convergence theorem providing a sufficient condition for quadratic speed of convergence of the method. After substituting the nonlinear characteristics with equivalent linear filters that compute Newton-Raphson on the existing network, through the basin delimiter, we figure out constraints guaranteeing quadratic convergence speed in the diode clipper. Further application to a ring modulator circuit does not lead to comparably useful constraints for quadratic convergence; however, also in this circuit, the basin delimiter has a magnitude roughly proportional to the number of iterations needed by the solver to find a solution. Together, such case studies foster refinement and generalization of this tool as a speed predictor, with potential application to the design of virtual analogue systems for real-time digital audio effects

A Swept-Sine-Type Single Measurement to Estimate Intermodulation Distortion in a Dynamic Range of Audio Signal Amplitudes

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Kitaravahvistimien digitaalimallinnus putkiteknologian korvaajana : Näkökulmia vahvistinteknologian kehitykseen ja vastaanottoon

Tämä tutkielma on tapaustutkimuksellinen lähestyminen musiikkiteknologian kehitykseen ja sen vaikutuksiin populaarimusiikissa. Tutkielma käsittelee kitaravahvistimien mallinnusteknologiaa sekä teknologisten toteutusten, historian, vastaanoton että käyttökokemusten näkökulmasta. Suosituimmat kitaravahvistimet on toteutettu pitkälti putkiteknologialla. Digitaalimallinnuksilla on toistaiseksi pyritty lähinnä toisintamaan perinteisempiä sointi-ihanteita mallintamalla suosittuja vahvistimia. Ensimmäiset digitaaliteknologiaa hyödyntävät vahvistimet, kitaraprosessorit sekä liitännäiset tulivat markkinoille 1990-luvulla, ja näiden osuus musikkituotannossa on lisääntynyt kasvavassa määrin muun muassa taloudellisista ja käytännöllisistä syistä. Teknologian ja kehityksen näkökulmasta lähteinä on käytetty alan tutkimuskirjallisuutta. Vastaanoton analyysin osalta aineistona on käytetty muusikoille ja harrastajille suunnattuja lehtiarvosteluja ja internetkeskustelua 2000-luvun taitteesta, sekä vuosina 2017–2018 tehtyjä musiikkiammattilaisten haastatteluja. Analyysissa on sovellettu sisällönanalyysin menetelmiä, ja hyödynnetty pääasiassa kvalitatiivista, mutta soveltuvilta osin myös kvantitatiivista analyysia. Digitaaliteknologian ja vanhemman analogiteknologian välisistä eroista käytävää keskustelua on tarkasteltu sekä käyttäjien mielipiteiden valossa, että tutkimuskirjallisuutta hyödyntäen. Analyysin tulokset kertovat siitä, kuinka eri teknologioiden suosimiseen liittyy useita syitä teknofobiasta uuden teknologian ihannointiin, sekä kitaristien sointi-ihanteiden konservatiivisuudesta musiikkiammatin ylläpitämisen haasteisiin. Uudempi teknologia vaikuttaa aina omalta osaltaan uusien sointi-ihanteiden ja musiikillisten käytäntöjen syntyyn. Laajemman kehityksen kontekstissa digitaaliteknologia samaan aikaan demokratisoi että homogenisoi populaarimusiikin muokkaantumista, kun laitteiden esiasetukset tulevat yhä useampien käyttäjien saataville. Noin 20 vuoden takaiset musiikkilehdistön laitearviot ja käyttäjien käymät internetkeskustelut eivät ole suoraan verrattavissa myöhemmin tehtyihin haastatteluihin. Tuloksia vertaamalla voidaan silti nähdä, että vaikka digitaalimallinnukset ovat kehittyneet huomattavasti niiden ensimmäisistä toteutuksista saakka, myös analogiteknologialla on yhä vahva kannattajakuntansa. Eri musiikkiteknologioiden suosimisen taustalla on siten nähtävissä eräänlainen arvojärjestelmä, joka ei ole suoraan palautettavissa ainakaan niin sanottuun kovaan teknologiseen determinismiin. Musiikkiteollisuudessa on havaittavissa laitevalmistajien, median ja muusikoiden symbioosi, joka ruokkii populaarimusiikin kehitystä yhä suuremman kulutuksen suuntaan

Simulações digitais de amplificadores de guitarra

Monografia (graduação)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Ciência da Computação, 2015.Este trabalho trata de métodos de simulação digital de circuitos analógicos aplicados à amplificadores de guitarras valvulados. São utilizados os métodos de Wave Digital Filters (WDF) para a simulação dos circuitos não-lineares, e o método da análise nodal para a simulação dos circuitos lineares de um amplificador valvulado. A análise comparativa das simulações é apresentada após as implementações dos métodos citados.This work deals with methods for the digital simulation of analog circuits applied to vacuum-tube guitar amplifiers. The wave Digital Filter (WDF) method is used for the non-linear circuits simulation, and the nodal analysis method is used for the simulation of the linear circuits of a vacuum-tube amplifier. The comparative analysis of the simulations is presented after the implementation of the cited methods

Estimating Performance Parameters from Electric Guitar Recordings

PhDThe main motivation of this thesis is to explore several techniques for estimating electric guitar synthesis parameters to replicate the sound of popular guitarists. Many famous guitar players are recognisable by their distinctive electric guitar tone, and guitar enthusiasts would like to play or obtain their favourite guitarist’s sound on their own guitars. This thesis starts by exploring the possibilities of replicating a target guitar sound, given an input guitar signal, using a digital filter. A preliminary step is taken where a technique is proposed to transform the sound of a pickup into another on the same electric guitar. A least squares estimator is used to obtain the coefficients of a finite impulse response (FIR) filter to transform the sound. The technique yields good results which are supported by a listening test and a spectral distance measure showing that up to 99% of the difference between input and target signals is reduced. The robustness of the filters towards changes in repetitions, plucking positions, dynamics and fret positions are also discussed. A small increase in error was observed for different repetitions; moderate errors arose when the plucking position and dynamic were varied; and there were large errors when the training and test data comprised different notes (fret positions). Secondly, this thesis explored another possible way to replicate the sound of popular guitarists in order to overcome the limitations provided by the first approach. Instead of directly morphing one sound into another, replicating the sound with electric guitar synthesis provides flexibility that requires some parameters. Three approaches to estimate the pickup and plucking positions of an electric guitar are discussed in this thesis which are the Spectral Peaks (SP), Autocorrelation of Spectral Peaks (AC-SP) and Log-correlation of Spectral Peaks (LC-SP) methods. LC-SP produces the best results with faster computation, where the median absolute errors for pickup and plucking position estimates are 1.97 mm and 2.73 mm respectively using single pickup data and the errors increased slightly for mixed pickup data. LC-SP is also shown to be robust towards changes in plucking dynamics and fret positions, where the median absolute errors for pickup and plucking position estimates are less than 4 mm. The Polynomial Regression Spectral Flattening (PRSF) method is introduced to compensate the effects of guitar effects, amplifiers, loudspeakers and microphones. The accuracy of the estimates is then tested on several guitar signal chains, where the median absolute errors for pickup and plucking position estimates range from 2.04 mm to 7.83 mm and 2.98 mm to 27.81 mm respectively