Systems List › DIY › Sundown ZV3-18D1 Sealed
The sensitivity measured was average for a long throw sealed 18” driver. It reaches almost 93dB with 1.4V at 55Hz but drops off away from that range and is down to about 87.5dB by 100Hz and 86dB at 200Hz.
The response shape results in the 100Hz response being down about 5.5dB and at 20Hz it is down about 18dB from the 55Hz peak. The ZV3 does employ a pair of shorting rings in the motor design but it is also a motor containing a lot of steel and a massive voice coil.
The group delay and waterfall decay plots show rapid and abrupt decay of energy which is just what you would want to see. The impedance measurement puts the impedance maximum at 42.5Hz for this driver+enclosure system. The results of the long term output testing show powerful wide bandwidth output is available that is impressive for a system of this size.
The deep bass frequencies never show significant compression due to the ZV3 drivers extremely long excursion capabilities. However a trend develops which is interesting showing that the response shape is shifting, with compression at 59Hz accompanied by expansion in output near 35Hz. Even at the 120dB sweep level the compression is 2.5dB or less which is good but this is offset by an expansion in output of about 2dB near 35Hz.
By the 125dB nominal sweep level there is a compression of about 4.5 dB at 59Hz and an expansion of output of 3dB at 35Hz. At this point the huge amount of power being dumped into the driver, the amount of response shifting and output compression seen coupled with the very high excursion levels that the driver is developing around 25-35Hz halted testing.
The distortion levels occurring during the levels used for the output compression sweeps show that the THD is well under control through the nominally 115dB output sweep with distortion well below 20% even in the 10-20Hz octave. Above 25Hz it is well below 5% THD. During the 125DB sweep which is punishing, the system still maintains respectably low distortion from 25-125Hz. Deep bass distortion rises precipitously but at that point the cone excursion is very large and this type of result is common for sealed enclosures pushed hard. There is a curious uptick in distortion at about 120Hz of which the cause is unknown. It corresponds with the 3rd harmonic as seen on the component distortion chart.
Overall the ZV3 based sealed system is dominated by H3 in the deep bass and upper bass and by H2 from 30-60Hz where distortion levels are low. Looking at the CEA-2010 burst output testing shows again that this system has generous headroom. Of particular note is the output from 25Hz to 50Hz which is very strong for a system of this size. The results from 10-20Hz were a little lower than expected but were limited by the 3rd harmonic.
The ZV3 driver had plenty of excursion left as the peak results without distortion considered show with some 6dB of output headroom left below 20Hz. Also of note is that while the distortion does increase in the deep bass, the driver did not emit the obvious mechanical sounds of distress that most other drivers do at high excursion. Many times this is subjectively more detrimental to the sound than even high amounts of deep bass distortion. This does not show up in the distortion results.