DIY Op Amps — Nelson Pass / 1998

Carl Sagan observed, "If you want to make an apple pie from scratch, you must first create the universe." If you want to build an audio circuit, you will make the decision as to how much you will actually build yourself, and how much you will buy fabricated. The line is always drawn somewhere. Will you be melting down some sand to make your transistors? Probably not, but it is always in the mind of the hobbyist to do as much as possible. Many of the project articles in AE and elsewhere employ commercially available integrated circuits, usually operational amplifiers.… More...

Like Peanut Butter and Chocolate — Nelson Pass / 2002

Pass Labs XA Series Power Amplifiers For over ten years, the Aleph series of single-ended Class A amplifi ers have received praise for their outstanding sonic defi nition, warmth, and smoothness; and have often been compared favorably with the very best tube amplifi ers. The Aleph topology achieves state-of-the-art performance with a very simple linear design, and is additionally one of the most stable and reliable audio amplifi ers in existence. A considerable number of audiophiles have found themselves bi-amping their loudspeakers, putting Pass X amplifi ers on the bottom for power and control, conjoined with Alephs on the top… More...