hifisonix

Tag: engineering

  • RIAA Equalizer Amplifier Design

    This article explores the fundamental’s of phono amplifier design,  culminating in a few practical designs. Special emphasis is placed on overload margins (critical if you want good sonics from your EQ amp), driving the EQ network adequately and noise. RIAA Equalization Amplifiers V2.0 Below is the RIAA Calculator Excel spread sheet.  Please read the article above,…

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  • Ground Loops

    Updated with new material 7th January 2019 This set of c. 70 slides is the culmination of my experience over a period of about 25 years building  power amplifiers and preamplifiers. I first started out in audio around 1975 or 76 as a teenager. Some of my creations were reasonably quiet – through pure luck…

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  • Amplifier History: The JBL SA-600

    The beautifully styled JBL SA-600 amplifier was launched by the James B. Lansing company in 1966, and Bart Locanthi (the designer) wrote the  technical article linked to at the bottom of this write-up in January 1967. I’ve included this in the hifisonix power amplifier library because it is one of the earliest – if not…

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  • Solid State Feedback Amplifiers: A Short History

    “Why, sometimes I’ve believed as many as six impossible things before breakfast.” ― Lewis Carroll, Alice in Wonderland     A Future Without Feedback by Martin Colloms There is no mysticism in amplifier design, just serious science. —Andrey A. Danilov Introduction You will recall from the The Theory of TIM by Matti Otala elsewhere on this site,…

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  • 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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  • JLH 10 Watt Class A Amplifier

    This is a copy of the original John Linsley-Hood article that appeared in Wireless World in 1969. This design, almost 50 years old, is still built in its hundreds all over the world.  A quick root around on the web will show numerous kits, many of quite acceptable quality, emanating from China and Hong Kong.…

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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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