How does Yamaha's Active Servo Technology work?

I have some small Yamaha speakers with Active Servo Technology that have very good bass for their size. I'm wondering if a similar circuit could be assembled from electronic parts for use on other small speakers? Thanks for any insight.

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  • 10 years ago
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    I think it would be prohibitively expensive and difficult for the garage engineer to manufacture.

    Yamaha's AST works by having a secondary coil on the speaker cone that induces a signal based on the movement of the cone itself. This is then fed back to an amplifier that adjusts the bass response depending on the signal that gets fed back.

    When current flows through a voice coil, it gets attenuated by the impedance of the coil. Especially bass signals, which require a lot of energy (therefore current) to reproduce. This causes a roll off in the bass response the higher you turn the volume up. By using the secondary coil to measure the amount of speaker cone movement and sending that back to the amplifier, the amplifier can be automatically adjusted to compensate for the the increased low-end attenuation caused by the higher volume audio signals.

  • 3 years ago

    Servo Technology

  • R
    Lv 5
    10 years ago

    Here's how the yamaha site explains this tech:

    "Advanced YST

    Advanced Yamaha Active Servo Technology (Advanced YST) is a unique system in which the speaker and amplifier work together to cancel out impedance so the speaker unit has a perfectly linear motion. Advanced YST helps to ensure the highest levels of sound pressure and overall performance."

    this is a circuitry that is not too much different than other brands' DSP "digital signal processing" +using feedback from the speaker feedback/ resonances to dsp the amp output.

    Pretty cool... Yamaha, along with other companies that use similar technologies like to give their tech special names fo the sake of marketing. So is it special? Not really, but does it work?- yes.

    I have a yamaha sub at home and it is quite compact: outputting nice accurate bass notes. Compared to my klipsch sub: it is not as loud and low: but that another story- so even yst has limitations.

    Yst=dsp -- and most audio companies use dsp in their own way to optimize their speaker output... So to answer ur ?- it is already implemented.

    Hope this helps!

    Source(s): Ps. Yst is a technology/patent introduced about 2 decades ago.
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