Test Report: Hsu Research VTF-15H Subwoofer Page 4

Few people fit into the target market for a subwoofer that can rattle not only your walls but also maybe even your neighbors' walls. Few people want to devote floor space for a subwoofer that measures 26 inches deep. But those devoted enthusiasts for whom the thought of getting a true state-of-the-art subwoofer for just $1,019 (including shipping) is irresistible will find that the VTF-15H delivers absolutely everything they expected and probably even a bit more.


TEST BENCH (revised September 16, 2011)

Frequency Response
24 to 149 Hz ±3.0 dB

Bass output (CEA-2010 standard, 2 ports open, EQ2)
Ultra-low bass (20-31.5 Hz) average: 119.2 dB

20 Hz 113.4 dB
25 Hz 122.1 dB
31.5 Hz 122.2 dB

Low bass (40-63 Hz) average: 123.2 dB
40 Hz 123.4 dB
50 Hz 122.8 dB
63 Hz 123.4 dB

Bass output (CEA-2010 standard, 1 port open, EQ1)
Ultra-low bass (20-31.5 Hz) average: 117.2 dB

20 Hz 114.8 dB
25 Hz 116.7 dB
31.5 Hz 121.6 dB

Low bass (40-63 Hz) average: 121.8 dB
40 Hz 120.0 dB
50 Hz 121.2 dB
63 Hz 122.7 dB

This is the second revision of these measurements, due mainly to various issues involving the CEA-2010 subwoofer output measurement standard. (These issues are explained in depth here.) Since the original review, I've acquired several new pieces of measurement gear and have completely remeasured the VTF-15H.

The CEA-2010 results presented here were measured with two different ways. The first set of measurements were taken with both ports open and in the EQ2 setting, this was the highest averaged output I was able to achieve. The second set uses the same settings that the Audioholics website used in their review of the VTF-15H, with one port open in the EQ1 setting; I used these settings so I could share information with Audioholics and Hsu Research. These numbers are a couple dB higher than the results I previously posted, which listed an ultra-low bass (20-31.5 Hz) average of 113.9 dB and a low bass (40-63 Hz) average of 118.9 dB.

No matter who measures it or how they measure it, the VTF-15H puts out tremendous low-frequency energy, especially for its price, and is exceeded in output by only a handful of subs currently on the market.

The measurement shown in the chart reflects the flattest and deepest bass response I was able to achieve with the Q set at the midpoint (0.5). This measurement was taken in the ported max extension mode, with one port plugged in the EQ1 setting. Both the EQ switch and the number of ports plugged affect the deep bass response. The least deep bass response is with both ports plugged in the EQ2 setting, which produced response down to 31 Hz. Activating the crossover produced a low-pass function of about 30 dB/octave.

Adjusting the Q setting has a measurable but not extreme effect on frequency response except in the bottom half of the bottom bass octave; the effect is barely noticeable at about 100 Hz but gets stronger at lower frequencies. Measured with both ports plugged in the EQ1 setting, the highest Q setting (0.7) delivered +4.3 dB boost at 20 Hz compared to the lowest Q setting (0.3). - B.B.