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 your power amplifier?
- How loud is the distortion produced by your 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!
The Benchmark AHB2 Power Amplifier
- Radically Different Topology
- Hi-Frequency Fully-Regulated Switched-Mode Power Supply
- Linear Class-AB output Stage with Class-H Tracking Rails
- Much more Efficient than a Traditional Class-AB Amplifier
- Feed-Forward Error Correction
- Correction Amplifier is Passively Summed with the Main Amplifier
- No Magnetic Interference
- No Relays in Output Stage
- Protection Circuits are not in Series with Output Path
- Low Gain Design
- Tweeter Protection
- 0.1 Hz to 250 kHz Bandwidth
- Stable into Inductive and Capacitive Loads
- Stable into Very Low Impedances
- 135 dB SNR
- THD is Better Than -110 dB at Full Output Power
