Loudspeakers

With a peak digital 0dBFs input, maximum output ('99' on the display) from Goldmund's Mimesis 15 digital preamp is –0.9dBFs, each step from '99' down to '31' representing ±0.5dB, a range of –0.9dBFs to –34.9dBFs. Volume '30' to '1' is achieved in ±1dB steps from –35.9dBFs to –65.9dBFs, with '0' as a digital mute.

As the Prana hosts inbuilt amplifiers, its sensitivity cannot be measured directly although the speaker's output was seen to increase by 0.5dB as the speaker cabinets, and drivers, warmed up by some +10oC. The forward response [see Graph 1] shows a 2.5dB step just prior to the 2kHz mid/treble crossover – skewing the response errors accordingly – and although this was largely unaffected by a mid or treble measurement axis, it is likely to be integrated out over a longer, say 3m, listening distance. The swift >20kHz roll-off suggests some additional filtering at work while the notches in response at 2kHz and 10kHz with the box-section grilles in place [blue trace, Graph 1] suggest they should be removed for 'serious' listening. The residual narrowband peaks at 1kHz, 4kHz and 7kHz also show as driver cone modes in the CSD waterfall [Graph 2], though the braced 0.5in-thick alloy cabinet walls are substantially more inert. Pair matching is truly excellent at 0.7dB, and tighter still at 0.4dB above 1kHz.

One of the benefits of combining DSP with an active speaker, Goldmund's Leonardo regime aside, is the possibility of optimising low frequency extension despite a relative small driver and limited cabinet volume. The wide, 340mm-deep port is tuned to 40Hz here and while the Prana's bass roll-off is steep below 50Hz it does reach the claimed 35Hz [–6dB/200Hz; shaded green area]. Nearfield analysis shows the port output is very clean and, at 1m, low frequency distortion – 2nd/3rd harmonic – impressively low at ~0.1% (100Hz/90dB SPL). PM