FVX12 has two port openings. With one port open, the max extension is 14hz and the bass extension toggle switch should be set to either 1P-music or 1P-HT. The latter is recommended for HT playback. The bass extension toggle switch needs to match the number of ports used.

In the following is the frequency response when bass extension is set to 1P-HT with one port open and LFE input.

Fig 1.0 - FVX12 Frequency response chart with LFE input 1P-HT and one port open

To achieve lower group delay in one port operation (such as for music playback), users can set the bass extension switch to 1P-Music. It has a more gradual roll-off and yet lower extension (-6db at 14hz) compared to that of 1P-HT. In the following is the requency response comparison between these two modes with LINE-IN input. The line-in input has a gradual roll-off at 100hz.

Fig 1.1 - FVX12 Frequency response comparison of 1P-music and 1P-HT with LINE-IN input

For highest SPL HT playback output, users should select 2P mode with both ports opened. While the extension is only limited to 20hz, the power of the amplifier is better utilized for audible frequency band instead of less audible sub-sonic band. In the following is the requency response of 2P mode.

Fig 1.3 - FVX12 2p mode response with LFE input and two ports open

One of the strength of directservo subwoofers is the consistency of the frequency response. FVX12 has a frequency response very similar to FV15HP/FVX15, making it easy to mix these subwoofers in the same room without phase issue as shown in the phase response plots.

Integration

One important aspect of getting a correct integration is phase alignment. We have written a guide on how to achieve a phase aligned subwoofer. More