HSU VTF-3 MK2 (maximum output)

[Ilkka]

Manufacturer: HSU Research
Model: VTF-3 MK2
Provided by: Takku
Manufacturer link: HSU Research : VTF-3 MK 2
Price: $699

Manufacturer specs:
Frequency response (Maximum extension mode) ± 2 dB 18 Hz
Frequency response (Maximum output mode) ± 2 dB 22 Hz
Frequency response (Maximum extension mode) ± 1 dB 20 Hz
Frequency response (Maximum output mode) ± 1 dB 25 Hz
Woofer size 12 inches
Amplifier power rating 350 Watts
Crossover frequency range 30-90 Hz, bypassable
Crossover slope 24 dB per octave
Crossover type low pass only
Phase 0/180°
Dimensions 22"(h)/15"(w)/23"(d)
Shipping weight 80 lbs.
Finish Black, Maple, Rosewood
Power Requirements 435 Watts
Warranty 7 Years on the woofer, 2 years on Electronics

Configuration as tested:
Phase: 0 degrees
Tuning frequency: 25 Hz (no port plugs)
Subsonic filter: 25 Hz (maximum output mode)
Orientation: Sideways

[Ilkka]

+/- 3 dB points: 20.5 Hz - 125 Hz

[Ilkka]

[Ilkka]

The HSU VTF-3 MK2 was one of the most exiting subwoofers to test, because there wasn't any comparable test data available for it. The shape of the frequency response is quite good, although it rolls off above 60 Hz. Therefore I wouldn't use it with much higher than ~80 Hz crossover. The built-in crossover doesn't go higher than ~70 Hz, but the lowest setting of ~30 Hz is really good for proper 2-channel use. A flat frequency response suits better for rooms not having much deep bass room gain. The mid bass output is really good for a 12" subwoofer, achieving well over 105 dB absolute levels. The deep bass output is compressed rather heavily around the tuning frequency due to small dual 3" ports. THD stays reasonably low at all frequencies, though starts to rise at the lower frequencies when output goes higher. There is a strange resonance at 68 Hz which makes the THD spike there even at low output levels; could be a cone or cabinet resonance. Group delays stays really low down to 33 Hz, but grows rapidly below. Spectral decay is typical for a high passed vented subwoofer, with lots of ringing near the tuning frequency. Spectral contamination tests shows higher than average output capability with lower than average distortion. The overall build quality is average.

+ Good extension
+ Good frequency response for larger rooms
+ High mid/upper bass output capability
+ Overall price/performance ratio

- Somewhat high deep bass distortion at high output levels
- Distortion anomalies/resonances in upper bass range
- High group delay at low frequencies