Velodyne Digital Drive Plus 18 subwoofer Windows Setup Program
Velodyne's room-management software, Digital Drive Plus (Windows only), uses two main screens to run the DD-18+'s automatic equalization routines. First is the Frequency Response and Parameter screen. This is split into two windows, the first displaying the room's frequency-response curve, the second showing the parametric EQ graph. To the right of the two screens is a dialog box that lists adjustments of volume, low-pass crossover frequency, subsonic filter frequency, subsonic filter slope, phase, and polarity. Just below the two screens is a second box where the user can select one of three equalization routines: Self EQ, Auto EQ, and Manual. A line at the bottom right tells you whether or not the DD-18+ is synced to a computer.
Self EQ is run with the audio system off and the subwoofer on. The subwoofer generates a sweep tone, which is picked up with its calibration mike; it automatically adjusts its internal parametric EQ filter levels and the contour filter frequency and level (boost). You can watch the subwoofer adjust its frequency response in real time on the Frequency Response screen. This mode sets the crossover frequency of the low-pass filter to 160Hz. No external laptop is needed, nor is any input from the user.
Auto EQ can be initiated from the subwoofer's front panel or from the Windows Interface Setup Software, as described above. Auto EQ's DSP algorithm requires the user to connect a PC to the DD-18+'s front-panel USB port with the supplied cable, and to connect and place the calibration mike at the listening position. When the software is run, the status line on the computer's Frequency Response and Parameters Screen indicates sync. Instead of an internal signal generator, the DD-18+'s Auto EQ and Manual optimization software and DSP circuits depend on 15200Hz, one-second sweep tones from a track on the Digital Drive Plus CD played in the user's CD player. When the DD-18+'s front-panel Auto EQ button is held down for five seconds, or the Auto EQ option is selected and initiated from the Windows Interface Setup software, the sub is muted to determine the main speakers' frequency response below 200Hz. The sub then unmutes itself and matches its output to that of the mains, and the program adjusts the sub's output level, frequency response, crossover filter frequency and slope, and phase, in addition to the parameters adjusted during Self EQ.
The Manual option allows the user to adjust all subwoofer parameters in real time from the computer's keyboard while the CD's sweep tone is playing. You start the sweep tone, then select and initiate Manual mode from the Windows Interface software. Then you adjust the frequency-response curves by clicking on a peak and dragging it down to make it flatter. The endless sweep-tone track gave me plenty of time to make adjustments using the virtual sliders on my laptop's screen. In addition to the parameters accessible via Auto EQ, Manual mode lets you adjust the subsonic filter frequency and slope, polarity, servo gain, and parametric filter bandwidth and frequency. Manual mode can also mute the DD-18+ to reveal the low-frequency character of the satellite speakers. Unique to this mode, frequency-response curves can be saved in addition to the parameter settings.
The second screen displays the five presetsTheater, Rock, Jazz, Custom, Gameseach of which can be adjusted in eight parameters: volume, low-pass crossover slope, subsonic frequency, phase, polarity, contour frequency, contour level, theater/music.Larry Greenhill