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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Ovation 250 Power Amplifier

The Ovation 250: A 250W per Channel Audio Power Amplifer (updated 1st June 2013) This amplifier was built in 2005/2006 and this write-up originally published in 2009. Introduction Diy Audio is a wonderful activity:-  if  you cannot  afford a $10 000  power amp,   you can always  build  one that comes pretty damn  close in terms of  sonics  […]

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CFA vs. VFA: A Short Primer For the Uninitiated

This article was written in 2014 in response to what can only be described as a vitriolic debate as to what constituted a CFA on diyAudio.com.  At the time, many of the participants were struggling to grasp the fundamental differences between VFA’s and CFA’s, and even how to tell them apart.  So, this document is […]

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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 […]

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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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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 […]

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