Edward J M
Senior HTF Member
- Joined
- Sep 22, 2002
- Messages
- 2,031
It's a "rumble" tone - a combination of bass frequencies, but mostly centered around 40-45 Hz. If you really wanted to know what it looked like, you would need to run a RTA spectral analysis of it.
The RS meter is c-weighted, and will read progressively lower as the frequency drops. Since the rumble tone is a bunch of different frequencies, it would be hard to assign "one" correction factor for it. But since it is largely centered around 40-45 Hz, the commonly accepted CF for the typical rumble tone is about 2-3 dB.
I could tell you exactly what the CF is for the rumble tone from my AVR 3803. All I would have to do is mount my test rig mic and my B&K SPL meter mic right next to each other in the near-field sub measurement location and run the test tone and compare the total SPL from the RTA display (which is unweighted) to the total SPL from the B&K meter (which is c-weighted). The difference will be the CF, but it would only be valid for the 3803.