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Modifikacija GRF Tannoy sa zvu�nom kutijom MK-3 u procesu izrade


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A Transmission Line Subwoofer

Designed & Built by Yves Mattei


 

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


    A Transmission Line Subwoofer

    Designed & Built by Yves Mattei

    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
         Audax PR 330 M0*
         Physical length    1.6 m              Sd    538 cm^2
         Physical fs at 1/4 wl    54 Hz              Vas    264 liters
         Acoustic 1/4 wl (measured)    2.13 m/40 Hz              Cms    6.5 e-4 N/m
         Measured c'    0.75c              Cas    1.9 e-6m^5/N
         (speed of sound in the line)              Mms    52 g
         Begining cross section    838 cm^2              Fs    27 Hz
         Terminus section    262 cm^2              Bl    13.6 N/A
         Taper    1.6 : 0.5 Sd              Re    5.8 Ohms
         First odd harmonic    140 Hz              Qms    6.7
         (null of driver, max of terminus)              Qes    0.28
         Max of terminus    90 Hz              Qts    0.27
         (level of the terminus is 3 dB below the driver )              Pmax    150 Watts
         Stuffing    50 mm Rockwool              Xmax    +/-4 mm
                    
    Plans
         
    * Audax HD 33 S 66 replaced by PR 330 M0
    Notes:

    Testing: Monacor MCE2000 electret capsule mounted in an amplifer g=100 that I built. I used a sinewave generator and a oscilloscope.
    The data on the phase was made using comparative measures with the dual trace scope
    [ <-- Back to Projects | Yves TL | Plans | Home Theater ]

  • 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)

YvesTLsm.gif

 

Line Configuration
  Audax PR 330 M0*
  Physical length 1.6 m     Sd 538 cm^2
  Physical fs at 1/4 wl 54 Hz     Vas 264 liters
  Acoustic 1/4 wl (measured) 2.13 m/40 Hz     Cms 6.5 e-4 N/m
  Measured c' 0.75c     Cas 1.9 e-6m^5/N
  (speed of sound in the line)     Mms 52 g
  Begining cross section 838 cm^2     Fs 27 Hz
  Terminus section 262 cm^2     Bl 13.6 N/A
  Taper 1.6 : 0.5 Sd     Re 5.8 Ohms
  First odd harmonic 140 Hz     Qms 6.7
  (null of driver, max of terminus)     Qes 0.28
  Max of terminus 90 Hz     Qts 0.27
  (level of the terminus is 3 dB below the driver )     Pmax 150 Watts
  Stuffing 50 mm Rockwool     Xmax +/-4 mm
         

 


Plans
 

 


* Audax HD 33 S 66 replaced by PR 330 M0

 

Notes:

  1. Testing: Monacor MCE2000 electret capsule mounted in an amplifer g=100 that I built. I used a sinewave generator and a oscilloscope.
  2. The data on the phase was made using comparative measures with the dual trace scope

 


[ <-- Back to Projects | Yves TL | Plans | Home Theater ]
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