Bob Cordell's QA403 Tutorial

QA40x
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Those of you deep in audio design probably already have one or two of Bob’s fantastic books on amplifier design. His first book (Designing Audio Circuits and Systems) goes broad, and his second book (Designing Audio Power Amplifiers) goes deep into amp design.

Bob has posted a tutorial HERE on using the QA403 for making a host of amp measurements. The amp under consideration is outlined in Chapter 4 (2nd edition) of the Designing Audio Power Amplifier book, and depending on options can do about 150W into 8 ohms. Some more background on the design considerations and tradeoffs was presented at Burning Amp in 2019.

I have both books on my nearest shelf in my office. They are that good!

5 Likes
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Thank you so very much for providing this excellent tutorial. This is exactly what I have been requesting. :grinning:

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Yes, to have such a talented engineer AND technical writer to spend time on this is huge I agree!

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Bob Cordell is an authority on audio amplifier design. In my opinion, his book ‘Designing Audio Power Amplifiers’ should be in the library of anyone who wants to engage in audio amplifier design. This book, in my humble opinion, together with Doug Self’s texts, is an important mine of news and information. In this regard, I recommend reading Chapter 26 (but Chapter 27 is also very useful) ‘Distortion and its Measurement’ of ‘ Designing Audio Power Amplifiers’ (second edition) for a correct interpretation of the results that can be obtained from measurements made with the QA403. Of course all this is just my own thinking