Analogni tri-stezni distorzijski efekt za bas kitaro

JANEŽIČ, JANEZ (avtor), Jankovec, Marko (mentor)

Popačenje zvočnega signala že desetletja igra veliko vlogo pri oblikovanju zvoka v glasbeni produkciji. Najbolj je razširjeno pri električni kitari, ki si jo že stereotipno predstavljamo s popačenim zvokom, ampak se je s časom, predvsem v moderni glasbeni produkciji, razširilo tudi na bas kitaro. Bas kitara v glasbi igra vlogo zapolnjevanja nizkih frekvenc in jo želimo popačiti zgolj zaradi zapolnjevanja višjega frekvenčnega spektra in umestitev v celotno »zvočno sliko«. Harmonsko popačenje namreč povzroči, da se v signalu pojavi več višjih harmonskih frekvenc. S tem pa pokvarimo nizke frekvence signala bas kitare, ki jih v glasbi večinoma skušamo ohraniti čiste (brez popačenja). V tem diplomskem delu želimo ta problem rešiti z analognim bas predojačevalnikom, ki nam bo na več signalnih linijah omogočal nastaviti katere frekvence signala želimo popačiti ter kako močno popačenje želimo; hkrati pa bo ohranil lastnosti nizkih frekvenc, ki jih ima čisti signal bas kitare. Idejo smo najprej preverili v LT Spice simulatorju, na podlagi simulacij načrtali tiskano vezje in izdelali prototip naprave. Rezultate meritev na izdelani napravi smo primerjali s simulacijami iz LT Spice. Meritve harmonskega popačenja (THD) se zadovoljivo ujemajo s simulacijami. Pri frekvenci 220 Hz smo izmerili razpon THD od 0,26% do 39,1%, kar se dokaj ujema s simulacijami (od 0,984% do 32,9%). Podobno se ujemajo tudi rezultati pri frekvencah 1 kHz in 2 kHz. Napravi smo dodali še 6-pasovni grafični izenačevalnik za končno oblikovanje zvoka. Želene resonančne frekvence posameznih pasov izenačevalnika so bile načrtovane pri 60, 150, 400, 800, 2500 in 7500 Hz. Resonančne frekvence pri izdelanem vezju odstopajo zaradi izbire iz lestvic vrednosti elektronskih komponent, ki so na voljo na trgu, in njihovih toleranc. Tako so izmerjene vrednosti resonančnih frekvenc 82, 157, 382, 1060, 1950 in 8000 Hz. Prototip naprave deluje zadovoljivo in po pričakovanju. Kljub odstopanjem v vrednostih simulacij in dejanskih meritvah, so rezultati povsem uporabni in naprava v celoti služi svojemu namenu.

• Jezik: Slovenski jezik
• Ključne besede: bas kitara, popačenje, analogni predojačevalnik, glasba, produkcija
• Vrsta gradiva: Diplomsko delo/naloga
• Organizacija: FE - Fakulteta za elektrotehniko
• Leto izida: 2021
• PID: 20.500.12556/RUL-131624
• COBISS.SI-ID: 79365891
• Datum objave v RUL: 30.09.2021

Sekundarni jezik

• Jezik: Angleški jezik
• Naslov: Analog three channel distortion effect for bass guitar

Izvleček

Distortion of the audio signal has been used in music production for decades. It's most commonly used with electric guitar, which is nowadays stereotypically associated with distortion, but with time it spread to the bass guitar as well, especially in modern music production. Bass guitar plays a role of filling the low frequencies in music and is usually distorted to fill the higher frequency spectrum because harmonic distortion introduces multiple higher harmonic frequencies to the signal. But with that we also damage low frequencies of the bass guitar signal, which we usually want to keep clean (without distortion). In this thesis we would like to solve this problem with an analogue bass preamp, which would allow us to choose which frequencies we would like to distort and how much distortion we would like on multiple different signal lines while keeping the low frequencies of the bass guitar clean. The idea was first tested in LT Spice simulator, then based on the simulations, we designed a printed circuit board and created a prototype. The measurements of the device were then compared with the LT Spice simulations. The measurements of the total harmonic distortion (THD) are closely matching the simulations. At the frequency of 220 Hz, we measured a range of THD from 0,26% to 39,1%, which is close compared to the simulations (from 0,984% to 32,9%). The results also similarly match at the frequencies of 1 kHz and 2 kHz. We added a 6-band graphic equalizer to the device for the final shaping of the sound. The desired resonant frequencies of each band of the equalizer were designed to be at 60, 150, 400, 800, 2500 and 7500 Hz. The resonant frequencies of the finished circuit are deviating due to the values of the electronic components being picked out of the standard series available on the market and their tolerances. The measured values of the resonant frequencies in the prototype are: 82, 157, 382, 1060, 1950 and 8000 Hz. The prototype works adequately and according to expectations. Despite the deviations in the results of the simulations and actual measurements, the results are functional and the device serves its purpose.

• Ključne besede: bass guitar, distortion, analogue preamplifier, music, production