Zdroje

https://sound-au.com/articles/eq.htm

https://www.premierguitar.com/articles/Everything_You_Ever_Wanted_to_Know_About_Preamp_Tubes

https://robrobinette.com/How_Tubes_Work.htm

https://guitar.com/guides/essential-guide/preamp-valves/

https://www.elektrolab.eu/blog/usmernovace-a-nasobice-napaetia

http://www.valvewizard.co.uk/Common_Gain_Stage.pdf