Rocket UFW10 Sub Curve Reading and Analysis
The curve shows the free-air, frequency response measurement (by ground-plane method) of the UFW10 Subwoofer with a 500 millivolt input. The single-band, parametric equalizer function was out of circuit. Average SPL is judged to be 104dB. Given a 104dB SPL average level the following observations/specifications can be assigned to the system's low-end response characteristic:
- Lowest frequency peak: 105.71dB SPL@ 36Hz
- Frequency at 104dB SPL average is 32.5Hz
- F3 or -3dB down point: 101dB @ 29.5Hz (You can still actually hear this.)
- F6 or -6dB down point: 98dB @ 27.5Hz (This is getting very hard to hear.)
- -10dB or 10dB down point: 95dB @ 26Hz (Most quoted number; for "spec" comparison only.)
The higher mid-bass frequency roll-off characteristic of subwoofers is quite important too. The UFW-10 sub has good, flat extension above 100Hz where it starts to roll off very gradually. A gradual roll-off such as this helps with the integration or "splice" as it's called between the subwoofer and the satellite speakers. A gradual roll-off as seen here usually indicates that a slight mid-bass EQ curve may have been applied electronically to alter the measured acoustic response as seen here.
A gradual roll-off like this is complementary when other software roll-offs will be applied to the system such as Dolby Digital or DTS. Specifications for the low pass characteristic:
- At 104B SPL average: 98Hz or 103.7dB SPL @ 100Hz
- -3dB or 101dB SPL @ 135Hz
- -6dB or 98dB SPL @ 228Hz
- -10dB or 94dB SPL @ 375Hz
This frequency response curve is fairly linear. A very tight (and honest) specification for frequency linearity would be 30Hz to 108Hz ±1.75dB.
