Live Video Tutorials

In this video, John Siau extracts the data from the published test results of 7 top-rated audiophile power amplifiers. Hidden within the THD+N vs. Power graphs are the answers to two key questions:

• How loud is the noise produced by my power amplifier?
• How loud is the distortion produced by my power amplifier?

Your Amplifier THD+N may be Louder than a Washing Machine!

Don't take our word for it! The evidence is captured in the hundreds of test reports compiled by Stereophile Magazine. Unfortunately, we cannot see this information when looking at traditional THD+N graphs. We need to extract the raw data from the Stereophile graphs and do a bit of math.

John Siau shows that the distortion produced by some of these top-rated amplifiers is louder than the noise that would be produced by having a washing machine in the middle of your listening room!

You wouldn't put a major appliance in the middle of your listening space, so you may want to take a careful look at your power amplifier.

Traditional THD+N Measurement Units Hide the Truth!

THD+N is usually plotted in terms of percent. This is a problem because percent is not a measure of loudness, nor is it a logarithmic unit. If we plot THD+N in terms of loudness (dB SPL) at the listening position, we can easily visualize the noise floor of the amplifier, and we can read the loudness of the THD directly from the graph.

Amplifiers are the Weak Link in the Electronic Chain

In most systems, the power amplifier will generate more THD+N than all of the other electronic components combined. It is time to take a fresh look at amplifier perfomance measurements. The evidence is hiding in Stereophile's test reports!

Feed-Forward Error Correction

Don't look back, the future is here!

Benchmark's AHB2 power amplifier has a unique feedforward error correction system that cancels distortion before it reaches the speaker terminals. In contrast, global feedback systems attempt to correct the distortion after it reaches the speaker terminals.

Feed-forward correction is fast, precise, and inherently stable.

Benchmark's AHB2 blends feedback with feed-forward correction to leverage the best characteristics of each.

Listen to Gene and John as they discuss this revolutionary technology.

• How does the feed-forward system know what correction to send?
• Does it predict the future?
• What makes feedback unstable when driving capacitive loads?
• Why is feed-forward stable when driving capacitive loads?

Take a few minutes to learn how feed-forward error correction works:

• Watch as John provides an easy-to-understand analogy for feed-forward error correction.
• Join the discussion.
• We reserve the right to limit negative feedback.

An Impossible Engineering Task?

Our goal was to produce an analog volume control with the highest achievable transparency. We wanted to be able to place this volume control in front of our AHB2 power amplifier or in front of our THX-888 headphone amplifier without diminishing the performance of either device.

Our volume control would need to have lower distortion and lower noise than either of these amplifiers. Given the extraordinary performance of these THX-AAA amplifiers, this would not be an easy task!

Our unique solution is a fully-balanced, low-impedance, relay-controlled attenuator with over 256 steps. Nothing like this was ever built, and nothing else matches the performance of the Benchmark analog volume control system used in the LA4 and HPA4 products.

The LA4 is not Just a "Good Preamp"

The LA4 was an all-out effort to build the best line-level preamplifier on the planet.

"Benchmark's LA4 is the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I have encountered." - John Atkinson

Watch as Benchmark's lead Engineer, John Siau, takes us on a deep dive into the relay-controlled preamplifiers inside Benchmark's LA4 and HPA4.

The AHB2 - A Radical Approach to Audio Power Amplification

Benchmark's AHB2 Power Amplifier is radically different from every other audio power amplifier on the market. It delivers the lowest distortion and lowest noise of any commercially available power amplifier. The THD+N and SNR specifications are 20 dB better than many high-end hi-fi power amplifiers. The unique high-efficiency design delivers hundreds of watts from a relatively small, passively cooled chassis.

Benchmark's lead Engineer, John Siau, will take us on a deep dive into the AHB2. You may be shocked by what is inside!

An Introduction to Benchmark

John Siau, VP and Director of Engineering, gives us an overview of his company, their design philosophy, and the pioneering products Benchmark offers for high-performance audio.

Benchmark Media, founded in 1983, has a rich history of innovation in the audio industry. Initially specializing in broadcast equipment, the company transitioned to high-end audio products in the early 2000s. Their commitment to engineering excellence has resulted in numerous accolades and a reputation for creating some of the most accurate and reliable audio equipment available.

John discusses some of Benchmark's key products, including the AHB2 power amplifier, LA4 preamp, DAC3, HPA4 headphone amp, and Studio&Stage(TM) audio cables. These products exemplify Benchmark's dedication to pushing the boundaries of audio performance, making them a favorite among audiophiles and professionals alike.