NOVA 2 - Frequency Response
Lab results are excellent. The non-smoothed frequency response is extremely flat
(some manufacturers are stating a smoothed frequency response over half
or the entire octave). The ribbon tweeter shows a slight emphasis beyond
15 kHz.
First the level for direct radiation under 0 degree angle:
Now under 15 degree:
The sound pressure level in relation to the dispersion is shown below.
The SPL was measured at 0, 15, 30 and 45 degrees from the main radiation.
Even here the frequency response remains flat. The increasing deviation
downwards at rising frequencies is determined by physics; a midrange driver
with a diameter of 13 cm stops radiating laterally at 2.5 kHz due to directional
focus, clearly shown in the diagram. Above 2.5 kHz the ribbon tweeter
takes over, only displaying a decline at 5 to 10 kHz.
NOVA 2 - Decay Spectrum / Waterfall Spectrum
The waterfall spectrum reveals any unwanted loudspeaker resonance. These are shown
by peaks moving over several lines to the front. This is not the case.
The Nova 2's decay is quick. 
Left:
Waterfall Spectrum
NOVA 2 - Impedance Curve
The Nova 2's impedance may be flattened for valve amps. The bass reflex
tube's resonance at 22 Hz and the woofer's (AC8 SW4) at 50 Hz is clearly
visible.
The Nova 2 is also highly resistive at 1.5 kHz, since the AC 5.25 HE-S
is highly efficient at this frequency. This means that little amplification
is needed and the crossover shows a high input impedance.
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