Audibility of different power supplies in a guitar amplifier
* Presenting author
While in most audio equipment a power supply is expected to provide smooth and stable supply voltages, this is commonly not the case for guitar amplifiers and, moreover, not even desired in principle. Historically, the expected sound of an electric guitar is in part shaped by power supplies with high internal resistances. These cause a supply voltage drop ('sagging') leading to compression of the output signal at the moment the strings are picked as well as to expansion of the sound during the fade out. In contrast, more modern power supplies operating with lower internal resistances and silicon diodes instead of rectifier tubes for rectification are ascribed a different sound by guitar players. This contribution compares power supplies in a classic guitar amplifier by measurements and in a listening test. The power supplies under study differ in terms of rectification (tube vs. silicon diodes) and size of the internal resistance. The results show that differences in the output signal of the amplifier due to different power supplies can be measured and also perceived under laboratory conditions.