Broken VU output amplitude after update

[Angel]

• With -14dBFS RMS / -11dBFS peak 1kHz sine the VU meter shows about -11dB
• With -14dBFS RMS / -8.5dBFS peak pink noise the VU meter shows about -6dB

Noise is very special signal. The RMS of noise is the same as the standard deviation of that random signal. It is known that in noise there are peaks larger than the standard deviation i.e. RMS. Thus the meter reading is higher, supporting my impression that it is more a peak meter (see sine) than an RMS meter.

 

[Hiwheeler]

I just want my bouncy meter back

 

[canard]

Need eventualy dbtp ( truepeak) levelmeter with ultra... and more sure.." overload" truepeak indicator informate in wiim home for all wiim machines

 

[DHS]

Noise is very special signal. The RMS of noise is the same as the standard deviation of that random signal. It is known that in noise there are peaks larger than the standard deviation i.e. RMS. Thus the meter reading is higher, supporting my impression that it is more a peak meter (see sine) than an RMS meter.

Perfect metering is a complex engineering! When calculating RMS ( root mean square ), you need to know averaging time (-> how many [squared] samples are used to calculate the mean value), influencing the „speed“ of the meter. And you need to know the „headroom“ (Crest factor) for the correct calculation of the RMS value.
Assuming a crest factor of about 10 dB for speech and noise signals plus assuming a 2 Volts peak fullscale, WiiM’Ultra RMS meter cannot accurately indicate speech or noise signals that are higher than approx 632 mV peak, respectively approx. 450 mV RMS. Therefore, signals that are higher than - 4.8 dBm will not be measured correctly (Preamp gain = 0 dB, no EQ or room correction). For pure sinusoidal signals with crest factor 3.01 dB, accuracy should be possible up to 1.414 Volt RMS, resp. approx. 5.2 dBm. I hope I am correct…