BAX EQ - Full Kit
Peter J. Baxandall was an English audio engineer and a pioneer of the use of analog electronics in audio. He is best known for the bass/treble tone control circuit that is now commonly refered to as the "Baxandall" or "Bax"
This unit draws directly from the original design, and implements a discrete opamp for gain (optional), as well as precision Blore Edwards switches (optional) for precise, matched and recallable gain settings.
There is no set canon for denoting shelving filter frequencies, so I "eyeballed" them on the plots. You can easily change them by changing the capacitor values in the frequency swtiching.
This is a very elegant circuit using great, basic ingredients, and you can do a lot with it in terms of changing the gain ranges, gain steps and frequency selection to your liking.
*Standard kit includes potentiometers and integrated circuits for the gain section.
*Mastering version kit includes switches and discrete opamps (+200 euros ex VAT)