Filtering 101: Multi Pole Filters with Real Poles

[MattDuffADI]

If the second stage does not load the first stage, then a two real pole rc filter will be 6 dB down. However if the second stage does load the first stage, then there is additional attenuation at the cutoff frequency. If the R's and C's are equivalent in the two filters, then it ends up being 9 dB down.

[canitasteyou321]

a two-real-pole rc filter will have 6 db down, not 9 db.