43 dB noise level from speaker with amps (not including pre-amp)

I measured the noise level about 10 inches from my speakers.

It swings from 40 to 45 dB.

Is this a normal noise floor? The number seemed high to me as when I play 80 dB music, I am assuming the signal to noise is 40 dB (80 minus 40).

Does this sound right? Or is there a mistake in my understanding.

dcaudio04-16-2022 2:01pm

gs5556 Details Discussions Posts This discussion Message User 1,242 posts 04-16-2022 at 05:02pm Copy Comment URL Report Comment Edit Delete Decibels are logarithmic, not linear. If the noise floor is 45 dB and you add another 45 dB from your speakers, the combined dB is 48. If you double the noise and add 90 dB to the ambient, the combined level is 90.00014. The numbers to the right of the decimal is the ambient contribution, which is essentially zero. The formula for adding two decibels dB1 and dB2 is 10 x Log [10^(dB1/10) + 10^(dB2/10) ]