PPSL KEF B139's Good idea or stupid?

I have a number of b139's and was wondering if slot loading them would be a sensible thing to do. I was thinking about 4 per channel. Wanting to cover the freq range upto 300hz where my jbl 2482's take over.

The other thought i was musing was how to load them, OB, BR or passive radiator PR ( i have a number of b139's which rub which i was going to take the magnets off) The reason for mentioning the PR is i thought this may improve the speed of the arrangement, as i am worried it may be slow compared with the CD's
KEF B139 SP1044, VB = 115.8 L, FB = 21.1 Hz with F3=31Hz/23Hz in room.

Max. SPL Distance from speakers/1.00 m
1 speaker 2 speakers 3 speakers 4 speakers 5 speakers
107.0 dB 110.0 dB 111.7 dB 113.0 dB 114.0 dB


  • KEF B139 SP1044, VB = 115.8 L, FB = 21.1 Hz, 86.3 dB2.83Vm..jpg
    KEF B139 SP1044, VB = 115.8 L, FB = 21.1 Hz, 86.3 dB2.83Vm..jpg
    132 KB · Views: 131
I have been modelling a slot loaded design and seems like that the plenum (cavity) resonance makes easily the limit around 200Hz. The depth of the plenum determines resonance, around 40cm deep gives resonance at 180Hz. The deeper - the lower resonance. Resonace means also huge phase jumps and poor impulse response at reonance and above it.

So, seems like I don't recommend using PPSL as high as you are planning

Hornresp is a wonderful tool for design, but a bit difficult


Hornresp for Dum... hmm... Everyone ;) - Home Theater Forum and Systems - HomeTheaterShack.com