Un subwoofer sectionat

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Constructie SubWoofer

This design is a single fold transmission line using a 330mm (12") Audax driver (HD 33 S 66). The port loads out the back. Very little stuffing is used. It as a SubWoofer in a Home Theater System with an active 4th order low pass at 70 Hz. Since the cross-over is low, upper resonnances ( > 150 Hz ) are not a big problem. This line is not optimized for higher crossover frequencies. Results: From 50 Hz to 100 Hz driver and terminus are in phase (+/-10°) The - 3dB point is near 45 Hz At the Fr of the line (40 Hz) driver and terminus are 90° out of phase Below 40 Hz they are out of phase The stuffing could have be better optimised, reducing the effect of the null at 140 Hz. If I were to do it again I'd make the terminus a bit larger. (or use the line for a 10"/ed) Since originally putting this project together more stuffing has been added making this a true TL. The preliminary results are that the stuffing improves the performance of the speaker. (details as they become available/ed)

Line Configuration Physical length 1.6 m Physical fs at 1/4 wl 54 Hz Acoustic 1/4 wl (measured) 2.13 m/40 Hz Measured c' 0.75c (speed of sound in the line) Begining cross section 838 cm^2 Terminus section 262 cm^2 Taper 1.6 : 0.5 Sd First odd harmonic 140 Hz (null of driver, max of terminus) Max of terminus 90 Hz (level of the terminus is 3 dB below the driver ) Stuffing 50 mm Rockwool

udax PR 330 M0* Sd 538 cm^2 Vas 264 liters Cms 6.5 e-4 N/m Cas 1.9 e-6m^5/N Mms 52 g Fs 27 Hz Bl 13.6 N/A Re 5.8 Ohms Qms 6.7 Qes 0.28 Qts 0.27 Pmax 150 Watts Xmax +/-4 mm * Audax HD 33 S 66 replaced by PR 330 M0

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