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What is a Subwoofer's Qms?

written by: Daniel Barros•edited by: Eric Stallsworth•updated: 1/25/2012

If you've ever wondered what a Subwoofer's Qms actually means, we've done the research for you inside.

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    Tech Talk

    Welcome, weary internet traveler. You’ve probably reached this site after having perused through various different highly-technical websites in your search for what a Subwoofer’s Qms has to do with its output capacity, and whether or not you should care. The quick answer is “yes" - you should care. Qms has a large role to play in determining whether or not your sub is as good as you think it is.

    The Qms is a physics term that has less to do with a sub than it does to do with resonant frequencies. This property of the speaker is simply a measurement of how often it will be able to operate at the resonant frequency, also known as the tendency to operate at this resonant frequency. Of course, telling you this explains absolutely nothing as to why you should be interested in the Qms of your sub.

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    The Inner Workings of the Subwoofer

    To understand things better, we’ll need to know what a subwoofer actually does. In the simplest terms possible, the sub handles the lower ranges of sound. Audiophiles will quickly tell you that any great audio setup needs a subwoofer to handle the deeper sounds, while a tweeter will handle the higher pitched sounds, and a mid-range driver to handle anything in-between. These three together deliver all the sound range that is capable of being heard by the human ear.

    Now, a subwoofer has a resonant frequency due to the nature of the equipment found inside the speaker. This is the system’s lowest natural frequency in Hz of sound, or also the highest natural frequency. But don’t worry about that – the resonance frequency is only important for those audiophiles crazy enough to build their own subs.

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    Qms and the Big Picture

    Now that we have a working knowledge of frequencies, the Qms comes into play. There is a tendency of the speaker to operate at the resonant frequency, so knowing this value allows you to make a more intelligent purchasing decision by selecting the speaker that has the highest Qms.

    Of course, selecting a subwoofer isn’t so much about these highly technical specifications, but rather about how much sound they can output. Higher watt ratings means more power and therefore louder and better sound quality. Sure, having a high Qms is a bonus, but even the best technically sound sub can falter if it has a low wattage. We'll look at more on this later though.

    The point of this is to make sure that you are adept at researching your system before you actually purchase it. Knowing what the Qms of your speaker is will be an excellent starting point, but don’t be afraid to get deep into the terminology – remember, knowledge is power if you don’t want to be ripped off online or at a subwoofer store.

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    Extra Reading

    This article assumes you know a bit about subwoofers, if you'd like to get started with these fascinating pieces of tech, check out these articles:

    How Does a Sub Work (In-Depth)

    Blu-Ray and Surround Sound

    Complete Beginner’s Guide to Surround and Subs

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