Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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FS: NEW Seas 7" Aluminum Cone 4Ω woofers

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  • FS: NEW Seas 7" Aluminum Cone 4Ω woofers

    Seas custom 7" (6-1/2″ nominal) 4Ω woofers based on L18RNX/P but with black anodized dustcap+cone and a low frequency optimized motor.

    Great for DIY Audio home or car use. Similar to ScanSpeak, Eton, Accuton, Morel, etc. Made in Norway.

    BNIB, $38 USD each, many available.

    4pcs, $175USD shipped to CONUS
    2pcs $95USD shipped to CONUS

    Shipping to US and Canada only. No overseas shipping - it's crazy expensive!

    • Black Aluminum Cone and Dust Cap
    • Low Loss Surround
    • Basket Outside Diameter = 176.0 mm
    • Xmax = 6.0mm (12.0mm peak to peak)

    Voice Coil
    • 39mm diameter
    • 2-layer copper wire
    • 4 Ω nominal impedance
    • Aluminum Former
    • Overhung Design

    Thiel/Small Parameters
    Free Air Resonance, Fo 29 Hz
    Moving Mass, Mms 22.18 g
    Force Factor, BL 5.4 N/A
    Impedance at Fo, Zo 31 Ω
    Voice Coil DC resistance, Rdc 3.23 Ω
    Effective Area, S 136 cm^2
    Mech. Resonance, Rmec 1.04 Ns/m
    Qms 3.9
    Qes 0.45
    Qts 0.41
    VAS 35.2 liters
    CMS 1.36 mm/N

    Suggested Enclosures


    Suggested cabinet volumes are between 7 and 15L. The latter yields a Butterworth alignment with a bass system resonance of 50Hz and a frequency response that is -3dB at 50Hz.


    Suggested cabinet volumes are between 10 and 25L. The latter yields a Butterworth alignment when tuned to 29Hz with a 2" ID x 10" port. The frequency response of this alignment is -3dB at 30Hz.

    Measurements and Example Crossover

    This custom Seas woofer was installed in a sealed enclosure and a passive crossover was designed for an acoustic 2nd order LR low pass transfer function with a crossover frequency of 2KHz. This is a great transducer for a 2 or 3 way bookshelf or tower speaker crossed over to a midrange from 100 to 750Hz or a tweeter at 2 to 3KHz.

    Attached frequency response graph with and without passive crossover (schematic also attached). Calibrated mic at 1M, 2.83V.