hifisonix

Tag: Andrew Russell

  • Restoring a 57 Year old Receiver: The Pioneer SX-1000TA from 1966

    I usually write about new designs, technical aspects of audio etc but on one previous occasion waxed lyrical about the JBL SA600, a vintage stereo amplifier from 1966 designed by Bart Locanthi, which has turned out to be one of the most popular pages on hifisonix.com – it regularly tops the monthly hits table. I…

    Read more

  • 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,…

    Read more

  • 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…

    Read more

  • 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,…

    Read more

  • 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…

    Read more

  • 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…

    Read more

  • 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:- …

    Read more

  • 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…

    Read more

  • Some Ideas on Temperature Compensation for Audio Amplifier EF Triples

    Temperature compensating an EF3 audio power amplifier output stage is not a trifling task.  There are 6 Vbe junctions, running at 3 different current densities, different temperatures and neither is the thermal performance of the heatsink assembly characterized in most DIY cases. This makes deploying a conventional 2 transistor  Vbe spreader (or Vbe multiplier as…

    Read more