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  • AHB2 Power Amplifier Black

    Power Amplifier

  • HPA4 Headphone Amplifier Silver

    Headphone Amplifier

  • LA4 Line Amplifier Silver

    Line Amplifier

  • Digital to Analog Converters

  • The "0-Ohm" Headphone Amplifier

    The "0-Ohm" Headphone Amplifier

    The Sonic Advantages of Low-Impedance Headphone Amplifiers

    - An introduction to "The 0-Ohm Headphone Amplifier" White Paper

    The circuits used to drive headphones are often added to a product without careful consideration of the difficult loads presented by high-quality headphones. The most common circuit is an opamp driver followed by a 30-Ohm series resistor. The series resistor provides short-circuit and overload protection while isolating the opamp from the inductance and capacitance of the headphones. The series resistor protects the opamp while keeping it stable. In contrast, today's state-of-the-art headphone amplifiers eliminate the series resistor, and use a high current driver. This change reduces distortion and flattens the frequency response when a headphone is driven. These new high-end designs are often called "0-Ohm" headphone amplifiers, and are essentially miniature power amplifiers.

    Headphone Output 1 mW into Sony MDR-V6 Headphones THD+N vs FrequencyThis paper provides measurements which demonstrate the significant advantages of headphone amplifiers with very low (near 0-Ohm) output impedances. A low output impedance increases the damping factor of the amplifier-headphone system. This paper will show that a high damping factor reduces distortion at the headphone input, improves the phase response, and flattens the frequency response.

    Download the White Paper:

    The "0"-Ohm Headphone Amplifier - John Siau 

    Additional reading:

    More information on headphones and headphone amplifiers can be found here.


    Also in Audio Application Notes

    Closeup of Plasma Tweeter

    Making Sound with Plasma - Hill Plasmatronics Tweeter

    by John Siau June 06, 2023 2 min read

    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.

    Hill Plasmatronics Tweeter Demonstration - AXPONA 2023

    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

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    Benchmark AHB2 Power Amplifier

    Audio Calculators

    by John Siau June 04, 2023 1 min read

    We have added an "Audio Calculators" section to our webpage. Click "Calculators" on the top menu to see more like these:

    THD % to dB Converter
    RESULTS
    THD dB to % Converter
    RESULTS
    Read Full Post
    Benchmark AHB2 Power Amplifier

    System Performance Calculations

    by John Siau June 03, 2023 13 min read

    If an audio system is composed of multiple components, we may have detailed specifications for each component, but we will not know the performance of the combined system without doing some calculations. You may have questions such as these:

    • Will my audio system produce audible noise?
    • Will my audio system produce audible distortion?
    • How will my audio components work together as a system?
    • How loud will my audio system play?

    Use Benchmark's online audio calculators to find answers!

    For example, if we know the output power of an amplifier, as well as the sensitivity and impedance of our loudspeakers, we can calculate the maximum sound pressure level that our system can produce.

    PEAK SPL CALCULATOR
    dB SPL (2.83 V,1 M)
     Watts
    RESULTS
    dB SPL

    This application note provides interactive examples that help to answer the questions listed above.

    Read Full Post