The Benchmark AHB2 power amplifier is named in honor of Benchmark's founder, Allen H. Burdick. Allen had a life-long passion for audio, and became one of the leading innovators in the pro-audio industry.
Allen's business ventures began in 1983 as "Benchmark Sound Company" where he operated from his garage in Dallas, Texas. He surrounded himself with a staff that shared his passion for achieving new audio performance "benchmarks". Benchmark's first product was a large mixing console for television and radio broadcast applications. In 1985, Allen changed the business name to Benchmark Media Systems, Inc., and relocated to a facility in his hometown of Syracuse, New York. By this time Benchmark was manufacturing the DA101 audio distribution amplifier for television studios. Allen's DA101 was a 40 W power amplifier card with astonishing specifications. It had a 160 kHz bandwidth, and a dynamic range of 130 dB. The DA101 was designed to distribute line-level audio through extensive distribution networks. Television networks often require many cascaded distribution amplifiers, and this places extraordinary demands on the performance of each individual amplifier. Allen's DA101 revolutionized audio distribution in the era of analog TV. Allen was a perfectionist and a prolific engineer.
Allen retired in 2006 due to health issues, but Benchmark continued to develop new products under the direction of John Siau. Allen's DA101 was never marketed as a power amplifier, but it became Benchmark's amplifier of choice for critical listening tests during the development of Benchmark's digital products. The recent development of the DAC2 converter family highlighted the need for a power amplifier that could match the performance of the converter, and Benchmark began an amplifier project that we code-named "PA2".
In many ways, Allen's DA101 helped define the performance goals of the PA2 project. Early prototypes were evaluated against the DA101. Benchmark's performance goals were achieved through the use of two new patented topologies from THX, the application of good engineering, and a high level of cooperation between the engineering groups at both companies. The result is an amplifier that Allen would have been proud to call a "Benchmark".
On September 27, 2013, the "PA2" was ready to go into production, but we still didn't have a final name for the new amplifier. The faceplates were machined and finished but needed to be printed with the product name. I began thinking about the technology in the amplifier and how this could be incorporated into the name. The amplifier delivered class-A performance, had class-H tracking rails, and a class-AB output stage. It then struck me that the letters A, H, and B were Allen H. Burdick's initials. The initials A.H.B. can be found on most early Benchmark schematics. Instantly it was clear to me that the new amplifier should be named after the man who inspired it! I announced the name to my staff, and we placed the order for the printing. Less than an hour later we got a phone call with the sad news that Allen had passed away.
In loving memory of Allen H. Burdick (June 29, 1942 - September 27, 2013).
- John Siau
Myth - "Damping Factor Isn't Much of a Factor"
Myth - "A Damping Factor of 10 is High Enough"
Myth - "All Amplifiers Have a High-Enough Damping Factor"
These myths seem to trace back to a well-know paper written by Dick Pierce. His analysis shows that a damping factor of 10 is virtually indistinguishable from a damping factor of 10,000 when it comes to damping the motion of a loudspeaker cone. This analysis has been examined and repeated in many more recent articles, such as a well-written post on Audiofrog.com by Andy Wehmeyer. Articles such as these are often cited as evidence that amplifier damping factor doesn't matter. The mathematical analyses are correct, but the conclusions are incomplete and misleading!
How fast things can change!
It is March 23, 2020 and we are currently battling the worldwide COVID-19 pandemic.
This application note will be a departure from normal. I will make a few observations about the current situation and then look at the nuts and bolts of how we reconstructed our operations in less than 48 hours. Benchmark is 100% operational, but nothing looks the same as it did last week.
- John Siau
As an engineer I like to use "rules of thumb" to make quick estimates that help to explain the physical world around me.
These rules of thumb are easy-to-remember approximations that eliminate the need for complicated and needlessly precise calculations.
If you feel discombobulated by the complexities of high school physics, there is hope! I encourage you to step back and take a fresh approach.
If you learn a few simple rules of thumb, you can unravel mysteries of the physical world, amaze your friends, and yourself.
In this paper I will present 15 simple rules that I find useful when working with music and audio.
- John Siau