Systems List › JTR Speakers › Captivator 4000-ULF
NotesThe 4000-ULF was placed on its side, outdoors and run through the usual gauntlet of measurements to assess its behavior and performance. The first measurements are to look at the general frequency response shape, the effect of the LF adjust knob and to observe whether there are any issues in the time domain. The basic response shape is flat and extremely extended down to the 10Hz range. With the LF adjust knob at maximum the response fits within a tight 2dB window from 10-120Hz outdoors. With the LF adjust at minimum the response below 25Hz gradually slopes down towards 10Hz. The maximum effect is at 10Hz where there is an 8dB range of adjustment. Even with the LF adjust at minimum the 4000-ULF may exhibit a rising "house curve" towards the deep bass in most rooms. The response is flat out to about 125Hz where it starts to roll off towards 500hz where it is about 36dB down. There appears to be something in the response at 140Hz which is likely the vent resonance or an internal standing wave. The 4000-ULF should have no problem meeting up with main speakers up to 100-125Hz. The group delay graph shows that the 4000-ULF is well below 1 cycle of delay until way down near 13Hz where it starts to exceed 1 cycle slightly. This will be completely inaudible. The rest of the time domain measurements show nothing of consequence.
The 4000-ULF was run with the LF adjust at minimum for the rest of the measurements because this is closer to the native response with the least amount of boosting to the low frequencies. The long term output sweeps start off at the usual drive levels referenced to the 50Hz output at 2 meters groundplane. Things progress smoothly through the 105dB sweep at which point the vent has just started to compress by 1.5dB. The compression near the vent tuning continues to grow beyond this point reaching about 3dB at 10Hz during the 110dB sweep and reaching 4dB of compression by the 115dB sweep. At this point the 4000-ULF is just starting to exhibit a bit of driver compression at the top of the measurement range, where about 1dB of compression is in evidence. Another 5dB increase in output demands causes the 4000-ULF to reach its limit below 20Hz and compress the output a large amount. From 50-120Hz the compression is still less than 2dB. The final 125dB sweep reveals that the 4000-ULF is out of headroom below 25Hz and produces no more output than the 120dB sweep below that point. Additionally compression from 50-120Hz is now reaching 2.5-3dB so the testing was stopped here. It appears that there is significant low end boost to the 4000-ULF's response even with the LF adjust at minimum. During the 125dB sweep the 4000-ULF reaches 106dB at 10Hz, which is one of the strongest readings that's been recorded by Data-Bass at this frequency, during this test type. Output rises smoothly from there to just under 118dB at 20Hz and finally reaches 125dB up at 36Hz, before dropping a bit to about 122-123dB over the rest of the measurement bandwidth. The output below 35Hz is strong indeed and places this as one of the most powerful low frequency systems that has been Data-Bass tested. During these slow sine wave measurements there was some vent chuffing and wind noise noticed around the vent tuning, especially during the loudest couple of measurements. Also a hint of driver distortion below 20Hz on the loudest measurement. The cabinet itself was remarkably inert and dead throughout. Overall the 4000-ULF was quite clean even driven to the limits with the exception of a bit of vent air noise at the 10-15Hz frequencies.
As usual the distortion was recorded at the same drive levels as used for the long term output measurements. The 105dB nominal sweep shows low THD levels below 5% indicating that the system is loafing and clean at this level. The 110dB sweep measurement shows that THD rises ever so slightly but is still around 7% or lower over the entire recorded bandwidth which is excellent. The 115dB measurement shows a bit larger jump in THD but it is still under 10% over the majority of the 10-200Hz range. The 120dB sweep is starting to reach the limits of the system and shows increased THD as one would expect. THD down at 10Hz is now over 40%with 20-25% from 12-22Hz. THD is also reaching roughly 10% over most of the upper bandwidth as well. The final 125dB measurement shows THD has now increased even further in the deep bass and is 10-17% from 40-160hz. This isn't a bad result considering the amount of output being produced, especially in the deep bass where most systems cannot produce this type of output at all. As usal the harmonic makeup of the distortion is primarily the 2nd and 3rd harmonics.
The short term, distortion limited, burst output for the Captivator 4000-ULF is much as expected from what was seen during the long term output testing and distortion measurements. The ouput headroom is generous to say the least and starts off strongly at the 10Hz vent tuning and remains powerful over the entire 10-125Hz range tested.