Worth investing in Helmholtz resonator to fix deep nulls at 41 and 82Hz?

[raindance]

Looks more normal now. I'll add that small + bass trap = likely not a bass trap. Mine are large floor to ceiling units from GIK in the front corners and make almost no change to the frequency response, they mostly reduce the decay time of room modes. In doing so, they improve the mid bass and upper bass which was getting swamped by a couple of modes.

I don't believe you ever said what speakers you had?

 

[polmuaddib]

Avalon Opus Ceramique are the speakers.
I used three of these bass traps.
When I bought them I measured with and without them and was surprised to see improvement of 6db. It reduced the narrow null. I can’t find that measurement but I will repeat it when I find the time.
I agree that it would take a lot more for meaningful result.