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Category: Technical
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…
Saturn V Rocket Performance Report
Absolutely nothing to do with audio, but a great read for the techies. This performance report was pulled together in the late 1960’s by Walter Haeussermann , one of the German rocket scientists who went to the US after WWII, where he settled and went on to have a spectacularly successful career with NASA. He…
CFA Diamond Buffer IPS: Does it Operate in Class B or class A?
There is a persistent assertion by small group of amplifier design practitioners that the diamond buffer input stage of CFA audio amplifier operates in class B (or AB) mode wherein there is a hard ‘handover’ between each half of the diamond buffer input stage as the input signal passes through 0V. The most recent claim…
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,…
Baxandall’s Original Tone Control Article from Wireless World 1952
This article was published in October of 1952, when Baxandall was 31 years old, the design having already won him a prize 2 years earlier in a competition. His design basically relegated other tone control circuits to the scrap heap, although cheap passive, or non-inverting circuits still persisted well into the 1980’s, especially in low…
Stan Curtis 60W Class A Amplifier from ETI
Stan Curtis was involved in both engineering and management roles in companies like Quad, Cambridge, Rotel (a family owned Japanese brand) Mission and Lecson to name a few. He is primarily an audio business consultant and remains highly respected and a noted product designer within the sector in his own right. This is his 60…