Bass traps? (to solve a suck out)

How broad is the width of the suckout? If it's narrow you should just ignore it. Bass traps or EQ won't help with narrow band suckouts. Try moving your listening position. Sometimes even a half foot in any direction can help.

Hi Gehuva, How do you know you have a big suckout there? And if so, where are the peaks?
Bob

Are your speakers running full range? If not then try them full range and move them another foot out from the wall. If your subwoofer is in a corner then you really need to reconsider moving it out into the room for a more even response.

61 Hz; that's specific.

Before getting into room accoustics, experiment with the positioning and integration between the sub and the speakers. Sounds like a phase issue to me.

Of course, it could be just the microphone or SPL meter you used. They are notoriously inaccurate at lower frequencies. Even the testing labs don't certify below 100Hz.

After playing around with positioning and settings and you still have the same issues, come back and discuss bass traps. A null at that frequency would indicate a fairly large room volume and, probably, an unusual ceiling.