Categories: Technical Reviews

Design and Circuitry of Stereo Integrated Amplifier, including Digital Room Correction and Dual Subwwofer Bass Management

In depth analysis and discussion of the design and circuitry of a stereo integrated amplifier, including digital room correction and dual subwoofer bass management: evaluating the HK 990 Stereo Integrated Amplifier.

This 3-part series provides a detailed discussion of the electronics and design of the stereo integrated amplifier.

Part 1 provides an overview and covers room correction systems.

Part 2 considers the challenges of adding digital inputs and digital signal processing to a stereo integrated amplifier, using block diagrams as illustrations. This segment is a good read for those interested in the internal operation of an AVR at the block level. Since the HK is a stereo unit, the blocks are less complex. Once you have a handle of the operations at a block level, then the transition from two to seven, or even eleven, channels becomes more straightforward. The second segment also comments on the quality of the data converters in the HK 990 and additional performance data when the unit processes a high resolution file.

Part 3 turns to the design and construction of the HK 990 at the circuit level. The analysis starts with the analog circuits in the direct mode, which is equivalent to an analog integrated amplifier. The designs of the power amp and phono stage are in the spotlight, and we also look at the tape recorder output and monitor function in more detail.

Tags: Circuit Design, Room EQ, Bass Management, Stereo Integrated Amplifier, Digital Room Correction

David A. Rich, Ph.D.

David A Rich received his MSEE from Columbia University and Ph.D. in Electrical Engineering from Polytechnic University of NYU. He specializes in analog and mixed-signal integrated circuit design, with a portfolio spanning from audio ICs for Air Force One to RF ICs for wireless cell phones. Holder of fourteen patents, David's industrial experience includes ten years at Bell Laboratories where he rose to Technical Manager. He has taught graduate and undergraduate courses in integrated electronics and electro-acoustics. David's interest in audio began very early under the influence of his father, who was a recording engineer during the halcyon days of RCA Records. He gained an early understanding of electronics building Echo, Heath, and Dynakits. At the start of quadraphonic sound, David was building decoders based on designs in Popular Electronics. During his teen years, he spent more time in the back of TVs than watching movies at the front of the set. He still has limited interest in things video. David has been a professional reviewer of audio equipment for more than two decades, serving as Technical Editor for The Audio Critic and Sensible Sound. He is a member of the Audio Engineering Society High-resolution Audio Technical Committee. Collecting classical recordings has been a passion that has run concurrently with involvement in audio hardware. David has a special interest in early- and mid-20th century American tonal composers. He is an avid fan of chamber music and leads the Selection Committee for the Bethlehem (Pennsylvania) Chamber Music Society Concert Series.