Systems ListDIYOthorn

System typeTapped Horn
DriverB&C Speakers 21SW152-4
Driver Size21 "
Number of drivers1
External volume18 ft3
Dimentions (Width Height Depth)24 " 36 " 36 "
Weight240 lbs
Native Tuning Frequency28 Hz
Aprox. Price$1500 USD


This system was developed around the B&C 21SW152-4 driver over a course of about 8 months in late 2010-early 2011. Cabs were finally built in the later half of 2011 and testing finally completed mid 2012. The goal of this system is high sensitivity coupled with very high output and power handling and extension with full power output to 30Hz from a cabinet form factor of 24x36x36". Intended use is for sound reinforcement requiring loud output levels over the range of 30-100Hz in very large spaces, outdoors, clubs and other venues. A tapped horn design was settled on with a low corner of 27Hz and developed for its combination of high sensitivity and good driver excursion control in the cabinet form decided upon. The cabinet itself is constructed of 18 and 12ply void free baltic birch and finished in Duratex. The basic cabinet design allows for handle, caster and input jack placement as well as allowing for a plate amplifier cutout if needed. Additionally quite a few other drivers which would be suitable in the Othorn cabinet design were identified as well, though the cabinet requires a driver having a lot of displacement coupled with a very strong motor and this naturally results in most of the drivers being fairly expensive. An adapter plate has also been built and designed to allow for switching between 18 and 21" drivers. Testing with other drivers will be done in the future.

Long term listening to this bass cabinet in a variety of different situations and rooms produced a positive impression with a cleaner sound than expected and loads of headroom. Despite a roll off starting just below 30Hz, in listening with most content the Othorn sounds deeper than expected. Probably because there really isn't a whole lot of high level content below 30Hz in music or live sound. As a result the listening impression with this cab are rather favorable. 

Testing the Othorn outdoors show that the months spent developing and tediously simulating the system have paid off well with most of the data matching the simulations rather well. Sensitivity is high and maximum output is prodigious to say the least. very strong output is maintained to 25Hz. Most of the typical resonances of a tapped horn design have been pushed up past 100Hz and out of band for most apps involving this cab. Distortion is very low when the cab is not being driven to the end of its rope. Waterfall and group delay measurements also look better than expected with some slight ringing near 110Hz but even that being better controlled than expected. 

Recommended processing for this cab are as follows:

  • Recommended maximum amplifier power: 6000w program (140 to 145 volts) even as little as 600w will produce quite a bit of bass
  • Recommended Processing: 24Hz Butterworth 18dB/Octave high pass
  • BP EQ1 107Hz Q10.0 -7.5dB
  • BP EQ2 84Hz Q2.20 +2.5dB
  • BP EQ3 44Hz Q2.80 -1.5dB