Transistor guitar amplifier

U ovom diplomskom radu konstruirano je i izvedeno tranzistorsko gitarsko pojačalo po uzoru na postojeće cijevno pojačalo kako bi se subjektivno i objektivno utvrdile razlike među njima. Gitarsko pojačalo se sastoji od predpojačala i pojačala snage. Predpojačalo je izvedeno pomoću dva unipolarna tranzistora J201 i kompresora kojima su se pokušale simulirati karakteristike cijevnog pojačala. Pojačalo snage izvedeno je s operacijskim pojačalom koji pruža naponsko pojačanje dok bipolarni tranzistori u push-pull konfiguraciji pružaju strujno pojačanje. Na oba pojačala provedena su osnovna mjerenja kojima je utvrđeno da postoje razlike u odnosima harmonika i prijenosnoj karakteristici. Razlika u prijenosnoj karakteristici smanjena je upotrebom kompresora. Slušnim testom utvrđeno je da postoje čujne razlike između pojačala čak i kada imaju sličnu frekvencijsku i prijenosnu karakteristiku te THD. Isto tako, testom u kojem sudionici pogađaju na kojoj se snimci nalazi cijevno pojačalo isključivo korištenjem sluha, pokazano je da ih se može zavarati. Uzevši u obzir provedeni slušni test, manju cijenu, masu i troškove održavanja može se zaključiti da tranzistorska gitarska pojačala zaslužuju priliku da ih se češće koristi.During this diploma thesis a transistor guitar amplifier was constructed and developed. It was modeled on an existing tube guitar amplifier in order to subjectively and objectively determine the differences between them. Guitar amplifier consists of a preamplifier and power amplifier. Preamplifier consists of two unipolar transistors J201 and a compressor that was used to simulate characteristics of a tube amplifier. Power amplifier consists of an operational amplifier that provides voltage gain while bipolar transistors in the push-pull configuration provide current amplification. The measurements had been made on both amplifiers. It has been found that there are differences in frequency and transfer characteristics. The difference in the transfer characteristic was reduced by using a compressor. Hearing tests found that there are audible differences between amplifiers even when they have similar frequency and transfer characteristics and THD. As well, a test in which participants find out which sound sample was recorded with a tube amp by the use of hearing is proven to be misleading. The performed hearing test, lower prices, weight and maintenance costs were taken in consideration and it can be concluded that the transistor guitar amplifiers deserve a chance to be used more frequently