The only frequency response chart I could find for the NS-1000M inexplicably stopped at 200 Hz, but according to that chart the NS-1000M starts to roll off at approximately 630 Hz with 200 Hz being approximately 6db lower. According to Hifi News test figures 53 Hz is another 6db down from 200 Hz which leads me to believe that 40 Hz is rolled off even further.
The selected setting on the F12's low pass filter should be either, the 3 or 6db down point of that filter so when combined with the natural rolloff point of the main speaker makes a kind of quasi crossover.
It might be worth a try setting the low pass filter at say 80 Hz and then adjusting it back to see if there is any improvement in your 40 Hz output.
The selected setting on the F12's low pass filter should be either, the 3 or 6db down point of that filter so when combined with the natural rolloff point of the main speaker makes a kind of quasi crossover.
It might be worth a try setting the low pass filter at say 80 Hz and then adjusting it back to see if there is any improvement in your 40 Hz output.