The A.H.B. Story
A.H.B.
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
Also in Audio Application Notes
Interpolator Overload Distortion
Most digital playback devices include digital interpolators. These interpolators increase the sample rate of the incoming audio to improve the performance of the playback system. Interpolators are essential in oversampled sigma-delta D/A converters, and in sample rate converters. In general, interpolators have vastly improved the performance of audio D/A converters by eliminating the need for analog brick wall filters. Nevertheless, digital interpolators have brick wall digital filters that can produce unique distortion signatures when they are overloaded.
10% Distortion
An interpolator that performs wonderfully when tested with standard test tones, may overload severely when playing the inter-sample musical peaks that are captured on a typical CD. In our tests, we observed THD+N levels exceeding 10% while interpolator overloads were occurring. The highest levels were produced by devices that included ASRC sample rate converters.
Audiophile Snake Oil
The Audiophile Wild West
Audiophiles live in the wild west. $495 will buy an "audiophile fuse" to replace the $1 generic fuse that came in your audio amplifier. $10,000 will buy a set of "audiophile speaker cables" to replace the $20 wires you purchased at the local hardware store. We are told that these $10,000 cables can be improved if we add a set of $300 "cable elevators" to dampen vibrations. You didn't even know that you needed elevators! And let's not forget to budget at least $200 for each of the "isolation platforms" we will need under our electronic components. Furthermore, it seems that any so-called "audiophile power cord" that costs less than $100, does not belong in a high-end system. And, if cost is no object, there are premium versions of each that can be purchased by the most discerning customers. A top-of-the line power cord could run $5000. One magazine claims that "the majority of listeners were able to hear the difference between a $5 power cable and a $5,000 power cord". Can you hear the difference? If not, are you really an audiophile?
Making Sound with Plasma - Hill Plasmatronics Tweeter
At the 2023 AXPONA show in Chicago, I had the opportunity to see and hear the Hill Plasmatronics tweeter. I also had the great pleasure of meeting Dr. Alan Hill, the physicist who invented this unique device.
The plasma driver has no moving parts and no diaphragm. Sound is emitted directly from the thermal expansion and contraction of an electrically sustained plasma. The plasma is generated within a stream of helium gas. In the demonstration, there was a large helium tank on the floor with a sufficient supply for several hours of listening.
While a tank of helium, tubing, high voltage power supplies, and the smell of smoke may not be appropriate for every living room, this was absolutely the best thing I experienced at the show!
- John Siau