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Tag: engineering
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…
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…
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…
The Theory of TIM – Matti Otala
Matti Otala follows up on earlier research on the subject of TIM. The Theory of TIM Matti Otala
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…
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…
More Notes On Cascode Amplifier Oscillation
Here is a short write up on cascode oscillation I did back in 2012 when designing and developing the e-Amp. Cascode Oscillation in Audio Amplifiers.pdf I recently (2017) had a recurrence of the problem on another high power design – some pictures are shown below. When I went back and looked at the notes above,…
Low Cost Isolation Amplifier for Industrial Applications
A Design Idea of mine that appeared in EDN around 2000. The article appeared with the title ‘Lost Cost . . . ‘ – seems someone got a bit mixed up. The idea has been referenced in a few papers on the web – always good to see! Low_cost_isolation_amplifier_suits_industrial_applications Here’s another one using a delta…
Augmented Feedback Error Correction (AFEC)
AFEC is a simple technique that augments the feedback of an amplifier to dramatically improve the Large Signal Non-linearity (LSN) distortion performance by up to 20 dB across the audio band. Additionally, AFEC acts to remove any DC offsets and also improve PSRR significantly. Augmenting the feedback in a manner similar to that described in…