Jason GT

Anthem AVM20/30/D1 - application of notch filter

This isn't getting much in the way of response over at AVS. Perhaps I should have started at the "home" of the AVM. I'm trying to get my AVM dialed in ... how do I apply the notch filter?

I have the room resonance filter turned on and centered at 39 hz. No matter what settings I use for filter width and depth, I don't get a corresponding drop in FR when using the AVM internal test tones.

For reference, these are my FR readings from the main listening position, with no EQ applied. I have used a RS analogue SPL meter and already applied the relevant low-frequency corrections:

FREQ (Hz) - SPL (dB)
18 --- 80.0
20 --- 84.5
25 --- 86.0
28 --- 86.5
36 --- 90.5
40 --- 91.5
45 --- 90.0
50 --- 79.3
56 --- 80.5
63 --- 89.5
71 --- 87.5
80 --- 84.5
89 --- 84.0
100 -- 84.0
111 -- 81.0
125 -- 78.5
142.5 73.0
160 -- 64.5

(it actually appears that I have a pretty flat room )

I'm trying to use the notch filter to smooth out the slight hump that I have between about 33 Hz and 45 Hz.

Tips/hints etc would be appreciated.
Thanks in advance!

Lewis Besze

Yep you're very lucky indeed. I have a huge 15db bump at the same region which is very common BTW.
Your current curve is actually looks like a "house curve" which many preffers over "ruler flat".
PersonallyI wouldn't touch it, but if you must I would center it around 40 hz with a 20/60[one third octave]and drop about 3-4db.I don't know why you don't see any results though.Perhaps the internal tones at fault? Use extrnal tones if you can.