B>Sidebar 1: On The Inside
Under the black bonnet adjacent to the big transformer are two Burr-Brown PCM1791A DACs (three of the four available channels are used) with a digitally governed analog volume control and a total of +4dB of preamplifier gain. Digital gain is only used to optimize the Diva's dynamic range with low peak-level signals.
Four shielded interconnects take the line audio to the top PCB and its four power amps. The two pairs of woofers are split between two 125W amplifiers, and the midrange and tweeter are each fed by a 75W amp, all class-AB. Their closest component relative is the latest in Naim's evergreen integrated "Supernait" series, the Supernait 3.—Paul Miller
Under the felt blanket. Inside the main speaker lies the streaming equipment, custom DSP, DACs, and four class-AB amplifiers. Electronics by Naim.
Occupying nearly the full height of the cabinet interior is the huge linear PSU, the DSP section, and the class-AB amplifiers (their heatsinks facing outward) that power its four bass units, midrange driver, and tweeter. Lowering the cabinet's center of gravity is a 700VA toroidal transformer (bottom left) feeding all the linear PSUs across the two main PCBs. A small switch-mode PSU under the black cover (bottom right) supports standby mode but is disabled the moment the loudspeaker is fully powered up.
Also under this shell is a SHARC processor—the brains of the system—which handles all the audio-related processing including file-format conversion and synchronous upsampling and downsampling in tandem with Naim's proprietary minimum-phase digital filter. This filter has a high ~60th-order roll-off and defines the Diva Utopia's practical 22kHz audio bandwidth (see the measurements section), within which the 150Hz and 2.5kHz crossovers are managed with low-order filters. Naim/Focal has resisted the temptation to iron-out every minute peak and dip in the speaker's forward response using the powerful DSP at its disposal, as the phase- and time-related distortions that this would introduce would outweigh any subjective advantage of a slightly flatter response.
Naim's choice of StreamUnlimited input streaming card (the silver can above the transformer) hands over to Naim's UWB ("Ultra Wide Bandwidth") network for wireless sync/audio/volume communication between the Master and Slave loudspeakers. (Wireless UWB supports 24/96 PCM; as Tom Fine notes in the review, a wired Ethernet connection between the two speakers carries a higher, 24/192 data rate.) Above lies an Atmel processor, which is responsible for all the non-audio control functions.
