DIY 2004
 

  Subwoofer  

Done - Front  
June 2004
 
After long time researching I decided to build new subwoofers and this time it should be dipoles as my main systems.
The sound from this new bas system is so free of room and cabinet resonance that every music I have played on them give the sub octaves a hold new dimension.

Impedance - Freeair Impedance - Dipole
 

Impedance - Drivers in free air, Fs=30Hz & Drivers in Dipole baffle the Fs resonance is now 27Hz !
P
lus a new resonance at 258Hz.

Freq. - Nearfelt Freq. - 50cm
 

Frequency response near felt & from 50 cm.
Again you can see the resonance peaks: +10dB at 258Hz and +4dB at 170Hz:
Behringer DCX2496 configuration:
+10dB Q=1  25Hz,   -3dB Q=5  170Hz,   -10dB Q=6  258Hz,   48dB L/R LowPass crossover 110Hz

 

Start 1   Start 2   Before Driver mounted   close-up 1   close-up 2   Back   Front
 

Drawing
 

The "cabinet" is made from an old furniture and the special arrangement of the drivers was the only way to have 4 x 12 inch drivers in a W-dipole configuration.

Peerless SLS
 

The drivers: 4 x Peerless SLS 830669 per channel.
This unit is made for subwoofers and has the right data for a dipole system:
Fs=26Hz, Qts=0,45 and has a fair max linear displacement.
Jan from Sound Image gave me the idea to use this driver.