Building the AHB2 Power Amplifier - The Poor Audiophile Interviews John Siau
AHB2 - John Siau Explains what's Inside Benchmark's Unique Amplifier
In a recent interview by The Poor Audiophile, John Siau, Vice President of Benchmark Media Systems, explains some of the innovations in Benchmark's revolutionary AHB2 power amplifier.
"John is a long-time audiophile. In fact, it was his love of music and audio that originally inspired his interest in electronics and prompted him to pursue a degree in electrical engineering at Syracuse University."
"“Benchmark is not new to power amplifiers,” John told me. “For almost 30 years Benchmark sold the DA-101 audio distribution amplifiers for studio use. These were small 35 W card-mounted power amplifiers with a 150 kHz bandwidth, a 130 dB SNR and very low THD+N. These cards were designed to distribute line-level audio signals, but they were capable of driving speakers. Because of their outstanding performance, we often used these cards to drive monitors in our own listening room.”"
"That long experience with the DA-101 gave Benchmark some ideas for the next generation amplifier. As John mentioned, the team at Benchmark wanted to build an amplifier to bring out the potential performance of their DAC2 products. Benchmark wanted a high power, passively-cooled power amplifier that equaled or exceeded the performance of the DA-101. It was at that point that Benchmark knew that the current technology and existing topologies by themselves wouldn't be sufficient for their needs."
"“As we examined this task, it became clear that we would not reach our goals if we designed a conventional power amplifier,” John said. “We realized that we needed to look at some unique solutions. We were very focused on eliminating crossover distortion in the output stage because we felt that this was one of the most important factors in the sonic performance of the amplifier. We began experimenting with ...”"
Additional Reading:
The AHB2 - A Radical Approach to Audio Power Amplification - John Siau
Also in Reviews
AHB2 Review - Constantine Soo, Dagogo
"The AHB2 bridgeable stereo amplifier ... was the topic of a recent discussion between American electrostatic panel speaker manufacturer Sound Lab’s president, Dr. Roger West, and me."
"In our discussion, he related his highly positive experience in driving even his largest, $55k Majestic 945 panels with the $7,000 pair of Benchmark Media AHB2 monoblocks, along with the $3,050 LA4 Preamplifier and factory XLR cables."
"Dr. West described the AHB2 as a class AB design using “feed-forward distortion reduction [thus removing] any possibility of pushing the margin of safety of a standard feedback loop, used in most amplifiers, into an unstable oscillatory mode.”"
"He further shared with me that “this is of most concern on powerful musical transients. The distortion of the amplifier in the balanced mode is astonishingly low even at just below the clipping level of 380 watts.”"
"The prospect of the AHB2’s specified distortion level of 0.00015% or lower when at full volume is comical at first glance, but upon actual audition the impact of the achievement is very audible from medium-high listening levels and upward."
"It was unlike any other sub-$20,000 amplifier I have auditioned."
"My audition of the Benchmark Media AHB2 amplifiers underscores the reason Dr. West is so taken by it, and confirms the design is best described as a watershed moment in the high-end audio industry."
- Constantine Soo, Dagogo
DAC3 Review - Jerry Del Colliano
"Benchmark is a stalwart brand in pro audio, but has carved out a very respectable niche in the audiophile world with their diminutive but powerful components."
"The audiophile world sometimes looks to the professional audio world for enlightenment, especially on the digital side of things, and Benchmark Media is one of the companies that we put high on a pedestal."
"They are hardcore digital engineers freezing their asses off in upstate New York as they come up with some pretty innovative ways to get your varied digital sources sounding as much like the master tape as possible. Thank you for your service, gentlemen."
"If you really want to hear what your music sounds like in today’s streaming-driven world, this might just be the DAC that you need to test out."
- Jerry Del Colliano, Future Audiophile
DAC3 & AHB2 - System Review, Trevor Butler, The-Ear.net
"I began with the DAC3 HGC and AHB2 powering the glorious Morel Avyra 633 three-way floorstanders."
"This pairing created a full-bodied sound which brought the recording to life."
"Notable from the off was the bass from the DAC3 HGC and AHB2."
"Wow! It was deep, tight and conveyed a real feeling that the electronics were in charge of the transducers."
"Involuntary foot-tapping confirmed the timing ability and the overall presentation was spot-on, the Benchmark electronics created a fluent sound across a vivid soundstage; performers evident both tonally and spatially in an easy-to-believe presentation that brought the performance close."
"The Benchmark’s ability to retrieve deep-down detail and display it so well across the soundstage, with accurate positioning and convincing layering, made for a glorious re-creation of the recordings."
"To my mind the AHB2 is an amplifier with no obvious characteristics of its own: the level of transparency is sublime."
"Above all, the improved transient response performance stood out in a presentation that was not only lively but incredibly fast and revealing. The attack and decay displayed was awesome and not something I expect at this price point."
"The Benchmark DAC3 HGC and AHB2 are cracking products, sonically superior to a lot that’s available and well priced."
"They are superbly designed and built to an extremely high standard."
- Trevor Butler, the-ear.net