Sidebar 3: Measurements
As this is an active loudspeaker, with both analog and digital inputs, many standard lab tests—including impedance/phase (amplifier loading) and speaker sensitivity—are redundant. We can examine frequency response, pair matching, and distortion; the latter is predominantly third-order but very low for a loudspeaker, at 0.2% for much of its working range (ref. 90dB SPL/1m, 100Hz–10kHz). This result might have been anticipated, because the Diva uses DSP and custom amplification for the two pairs of 165mm "W"-coned bass units, matching 165mm mid and 27mm "M"-shaped beryllium tweeter.
The large, down-firing port, channeled by the Diva Utopia's integral alloy plinth, is tuned to 40Hz and is remarkably clear of any quarterwave or other cabinet/port modes. Combined with the quartet of actively driven 165mm bass drivers, whose output peaks around 100Hz, it supports a diffraction-corrected bass extension of 34Hz (–6dB ref. 200Hz). While the roll-off is steep beyond this point (green shaded area, fig.1), the Diva Utopia's bass weight can be further reinforced by near-wall positioning, although Focal recommends that this speaker still be kept clear of room corners.—Paul Miller
Fig.1 Focal Diva Utopia FR: nearfield-summed (green), freefield corrected to 1m (yellow), ultrasonic (pink). Main speaker (black), slave (red), with grille (blue), ±15° (gray).
DSP also allows for some control over forward and off-axis response, but fig.1 demonstrates that Focal has approached this with a light touch, resisting the temptation to iron out minor ripples around the mid and beryllium dome crossover from 3–6kHz. Other driver/side panel modes can be seen in the 500Hz–2kHz range (see CSD waterfall, fig.2). Otherwise, the response is slightly dished, but the errors are small at ±2.4dB and the pair matching truly superb, at 0.3dB (all ref. 200Hz–20kHz).
Fig.2 Focal Diva Utopia, CSD waterfall plot: The low-level modes up to ~2kHz are linked to the side-mounted woofers and aesthetic cladding.
The optional midrange grille has little adverse impact (blue trace), while the speaker's response is arguably even more uniform with a slight toe-in (gray trace). The ~22kHz response limit seen here is a function of Naim's digital filter, and there's a latency of 10.5ms for both the Master (left) and Slave (right) channels.
