hifisonix

Tag: audio

  • Hifisonix X-Altra Mini II Line Preamplifier with Remote Control (Deprecated)

    The X-Altra Mini II has been discontinued as a complete project. The individual PCBs are still available over in the shop however and are great line stages and power supplies. The X-Altra Mini II is a superb preamplifier and it sits at the heart of my system, but it was complex with lots of inter-module…

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  • Hifisonix Standard PSU

    Click here to buy a PCB for the Standard PSU Click here for the build documentation Click here for the BOM The Hifisonix Standard PSU features low noise, up to 400mA per rail output current, a MUTE relay driver to ensure when the load powers up or down there are no clicks or thumps, a…

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  • Class A Buffering the Correct Way

    Here’s a simple way to force an opamp output stage to run in class A when used with a discrete buffer output stage – it takes just 1 resistor to provide a near constant current source load. Operating the opamp (and the output buffer stage) in class A dramatically reduces harmonics on the power rail…

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  • Disc Recording Equalization Demystified by Gary A. Gallo

    Pictured: A Neumann Cutting Lathe used to make the record master. Picture courtesy of Bakery Mastering This is one of the best non-mathematical introductions to the RIAA disc recording playback chain written. Gallo worked at the Crane School of Music in New York for 30 years as an audio engineer, where he also received a…

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  • Audio Power Amplifier Design – Peter J Baxandall

    In this 6 part series of articles published from January 1978 in the now defunct Wireless World magazine, Peter Baxandall takes the reader through some of the fundamentals of audio amplifier design as they were understood at the time. Baxandall_Audio Power Amplifier Design In 1978  there was still much discussion about feedback and how to…

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  • The Theory of TIM – Matti Otala

    Matti Otala  follows up on earlier research on the subject of TIM. The Theory of TIM Matti Otala

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  • Review of Bob Cordell’s Book ‘Designing Audio Power Amplifiers’

    ‘Designing Audio Power Amplifiers’ by Bob Cordell  – Reviewed by Andrew C. Russell in 2011 Bob Cordell (on the right) pictured with Jan Didden, publisher of ‘Linear Audio’ After a 15 year hiatus from electronics, I returned in 2005 to linear design not as a professional but as a hobbyist. Earlier in my career, I…

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  • Barney Oliver: Crossover Distortion in Class B Audio Amplifiers

    This is the famous analysis of class B amplifier cross-over distortion by the then head of HP Reasearch Labs, Dr. Barney Oliver,  published in the February 1971 edition of the HP Journal.  The  bias current Iq for a class B emitter follower amplifier is shown to be approximately  Iq = .026/(Re+re+(rb/hFE)). In practice,  – the…

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  • Baxandall’s Original Tone Control Article from Wireless World 1952

    This article was published in October of 1952, when Baxandall was 31 years old, the design having already won him a prize 2 years earlier in a competition. His design basically relegated other tone control circuits to the scrap heap, although cheap passive, or non-inverting circuits still persisted well into the 1980’s, especially in low…

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