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Category: Articles
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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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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…
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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…
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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…
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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,…
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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…
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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…
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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…
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Hifisonix UBx Universal JFET Buffer
A while back, one of the diyAudio forum members who was building the nx-Amp (here’s the thread on DIYaudio.com) enquired about either reducing the amplifier’s overall gain, or providing a volume control facility. Since both the 15 W class A sx-Amplifier and its bigger 100W sibling the nx-Amplifier, are Current Feedback Amplifiers, performance is quite…