Systems List › DIY › Othorn
NotesThe Othorn system produces a good 1w/1m sensitivity with an input of 1.86v producing between 98 and 100dB over the range of interest for this cab which is 25-100Hz. The response shape fits within a 6dB total window from 27.5-93Hz and shows a steep roll off below 30Hz as the driver unloads from the horn path and a sharp peak at about 107Hz with increased sensitivity from 100-200Hz. The peak at 107Hz is the 5th harmonic of the tapped horn cab and is typical of this type of alignment. There are also peaks at other points in the response again corresponding with harmonics of the cabinet loading. Still the magnitude of these peaks and the response shape above 100Hz is much cleaner than many other horn system that measurements have been shown for. In a pinch with some EQ the Othorn could probably be run up to almost 180Hz but due to the dips and peaks in a tapped horns response often indicating severe resonances and ringing this is not advisable.
Looking at the response and decay of the response in the time domain shows that the Othorn is very clean below 100Hz with low group delay and no ringing of note other than near the peak at 107Hz but even this rapidly decays by 30dB or more. This system lacks the severe resonances noted in the DTS-10 tests and the Gjallarhorn. This likely contirbutes to its unexpectedly neutral sound.
Moving on to the long term output compression tests which have a 3rd order butterworth high pass to protect the cabinet below the corner, the Othorn exhibits brutal output capabilities due to a combo of high sensitivity, large driver displacement and tons of thermal power handling. Compression is very good up until the final 130dB nominal sweep which required an input of 121 volts and resulted in around 3 to 4dB of compression most of it probably thermal but some potentially resulting from a loss in driver displacement linearity. (This would correspond to about 4300w into the impedance minimums though impedance rise likely reduced this somewhat.) The major point of compression occured at the 107Hz peak which is similar to what has been seen in other tapped horns tested like this. In typical use this peak would be EQ'd down and then subject to roll off due to a low pass filter which will reduce the power input and compression in that range. The repeat 90dB sweep conducted immediately after the 130dB sweeps shows that there is some heat build up in the driver but considering the multiple minimum motion points present through the passband in a TH and the huge amounts of power being delivered this again points to the impressive thermal handling characteristics of the 21SW152-4 driver.
The distortion results from the drive levels used for the various long term sweeps show exceptionally low distortion up until the output levels and input power reach dizzying levels. Even during the 130dB 121v sweep the distortion over the primary range of interest 24-95Hz stays under 12% THD and the large spike that appears near 38Hz is likely to be the driver starting to run into nonlinear excursion behavior. If the level is dropped back to a 68v input and the the 125dB sweep the THD drops dramatically to less than 8% anywhere between 24-95Hz and between 25-60Hz is well below even 5% THD. This coupled with the huge output headroom available produces an exceptionally clean, pure and "relaxed" bass sound. The icing on the cake is that except for a brief point near 35Hz the distortion is composed of primarily the 2nd harmonic from 16-125Hz which is audibly the most benign.
CEA-2010 maximum burst output results reveal that this system is remarkably powerful and maintains good linearity between 30-125Hz. The Othorn produces the highest specific output recorded yet at a number of the 1/3rd octave frequency bands and is overall the most powerful system yet tested 25-125Hz. Output of over 122dB at 25Hz and 128.3dB at 31.5Hz measured at 2m GP indicate that the system can keep up with low bass tones in this range without compression or nasty overload noises even at very high playback levels in large spaces. From 35Hz on up the output available in in excess of 130dB short term. At 100 and 125Hz clipping of the sound card input was encountered as the levels reached 136dB.