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What's old is NEW again. Peerless XLS in sealed box, F3= 23Hz

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  • What's old is NEW again. Peerless XLS in sealed box, F3= 23Hz

    So what started as an experiment in building a stand for my monitors morphed into a 3 way project, inspired by Jeff Bagby's work on the Kairos & Continuum 3-ways.

    Why build just speaker stands when you make the most of the real estate, fill the space beneath the monitors some old drivers and have a convertible 3 way?

    Soon I learnt that the old dog Peerless 10" XLS (830452) can learn new tricks, thanks to modern, affordable measurement equipment and DSP.

    When this woofer was first released in the 21st Century (2001), the data sheets seemed to suggested a ported box (with length that was unpractical) or a passive radiator box. There's an application note on the www from Peerless saying that it wouldn't work in a sealed box, because 20L closed box F3 was around 100Hz, which of course leads to a conclusion that it's unsuitable for a sealed box loading-
    URL: http://www.d-s-t.com.au/data/Peerles..._Subwoofer.pdf

    But after building it, I was surprised that the F3 was around 55Hz. Using real measurements and DSP to dial in a boost, I was able to achieve an F3 of 23Hz.

    Below you can see unsmoothed measurements taken first in the nearfield (20mm from the cone), which is accurate from 10Hz to 500Hz.
    I put a LR2 LPF at 200Hz to integrate with my monitors.

    The far field measurements are at 2', so you can see some of the effects of the room, particularly below 100Hz, where things get wobbly due to the influence of the room. There's a balance between taking them too close (overload the microphone) and too far (too much influence from the room) so in the end I took them at 60cm.

    For me it was quite instructive to see that this woofer is still an goody, despite being over a decade old. Distortion measurements to come...
    Last edited by tktran; 05-24-2018, 10:26 AM.

  • #2
    I measured distortion levels, from 2.83V and up 32V, as well as ~94dB @ 1m, ala Voice Coil Test Bench style, as well as stress level to determine maximum SPL, as defined by the CEA 2010 standard for measuring subwoofers.

    It's quite instructive to realise that all those insane level of >100dB, the noise from one of the loose woofer screws, the rattling windows, furniture and doors in the room are more offensive and obvious than the woofers themselves!

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    • #3
      Before you say, pics or it didn't happen-


      Cabinet 60x30x40cm (HxWxD)
      50L internal volume. Moderately stuffed with glass fibre wool.
      Two 10" XLS woofers, wired in parallel (N.B you will need a amplifier capable for 2.5ohm loads)
      +6dB boost centred at 26Hz, Q 0.8

      F3 = 23Hz, F10 to below 16Hz (the sound of one hand clapping)

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      • #4
        In the days of subwoofers with over 2" one way x-max, these are pretty ordinary at 12.5mm. But note how the 3rd harmonic remains beneath the 2nd harmonic below 300Hz, so they really did well on designing the motor and soft parts (suspension and spider) on this unit.

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        • #5
          I think the most important thing I've learnt is to not always rely on the box models. You can really limit your options if you do this.

          Thanks to John kreskovsky and Jeff Bagby for the inspiration.

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          • #6
            Would there be excessive pressure on the cone?

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            • #7
              Originally posted by ontariomaximus View Post
              Would there be excessive pressure on the cone?
              How do you mean? In regards to small box size, or EQ boost?

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              • #8
                This woofer recently caught my eye and after modeling it in both sealed and ported enclosures realized that this is quite a remarkable little driver in small enclosures. I'm interested in putting together a new project using it so I'm excited to see someone else out there with it who is happy with it as well. Besides, I love the look of this driver! I don't know what it is, that massive surround or just the proportion of the surround to its size. It just looks beefy as all get out. Thanks for sharing.

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