hifisonix

Category: Articles

  • The Endless Semantic Debate: Current and Voltage Feedback Amplifiers

    It seems some are still agonizing over the ‘current feedback’ versus ‘voltage feedback’ definition.  Clearly a case of people wanting to continue to flog a horse that was laid to rest five decades ago during the heyday of the analog computer, or they simply fail to grasp the CFA concept. I suspect there are an…

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  • The Tale of Two Recordings

    I thought I’d share my thoughts with you on the sound of two LP’s I recently acquired.   Many of you will have heard of the term ‘sound wars’ which has been coined to describe the relentless increase in the use of  dynamic range compression in modern recordings, a development it could be argued from the…

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  • Hifisonix ‘Symphony’ Line Preamplifier

    I designed and built this preamplifier while living in Taiwan a few years ago. The Symphony preamp features Baxandall tone controls, up to 7 inputs,  a class A 2 W headphone amplifier and a Goldpoint 24 position attenuator.  The write-up describes the design process and choices in some detail and my listening impressions: Part 1…

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  • Ovation e-Amp: A 180 Watt Class AB VFA Featuring Ultra Low Distortion

    The e-Amp is a 180 Watt RMS (very conservatively rated into 8 Ω ) fully balanced symmetrical (‘FBS’) amplifier featuring an emitter follower triple (EFT) bipolar output stage and beta enhanced VAS stage. The amplifier can be configured using jumpers for TMC (Transitional Miller Compensation) or straight Miller compensation (MC). The VAS can be lightly…

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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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  • Ovation 250 Power Amplifier

    The Ovation 250: A 250W per Channel Audio Power Amplifier (updated 1st June 2013). This amplifier was designed and built in 2005/2006 as my first foray back into audio design after a nearly 20-year hiatus, This write-up was originally published in 2009 when I was living in Tokyo, Japan. Introduction Diy Audio is a wonderful activity:- …

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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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  • Douglas Self’s 8 Distortions and a Few More

    (pictured above is the hifisonix 180 Watt per channel e-Amp) No one had codified all the major audio amplifier distortion mechanisms until  Douglas Self published the first edition of his ‘Audio Power Amplifier Design Handbook’ or APAD’ as it has become known, in 1996.  He used a standard Lin* topology amplifier and then proceeded 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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