Need help with room and speaker setup, big dip from 250-80hz


I have a very small and odd room.  The room itself is 9' wide by 10' long with 9' ceilings.  The wall directly behind my head is only 3' tall, above that it opens up to my family room and kitchen.  I have the speakers firing down the 10' length.  The speakers (Sonus Faber Guaneri Evolution monitors) are toed in directly at my head, 3' from the front wall, and 1.5" from the sidewalls.  I have bass traps in the corners, absorption at the 1st reflection points and ceiling, and a mix of absorption and diffusion on the front wall.  My listening chair is right up against the short back wall.

I just did a quick measurement of my room using a cheap RS SPL meter and some test tones.  It seems I am -6db at 630hz and 250-80hz.  Any advice what I can do to help alleviate these dips?  As you can tell by my room dimensions I do not have a lot of flexibility.  Thank you.
128x128tboooe
The port on these speakers appears very small, and could be causing a reflection off of the wall/corner that effectively cancels out the frequencies you mention.

First - remove the bass traps - temporarily

Try different distances from the wall with the speaker toe-in at around 5 degrees. Keep the speakers about 7 feet apart to start with.
 
Once you have reasonably good bass performance try varying the space between the speakers and then adjust toe-in for a final adjustment

Once you get a pleasing sound re-install the bass traps to see if they are over compensating on certain frequencies

You may then need some minor adjustments for best sound once the traps are installed
 
I have a pair of studio monitors that suffers from a similar problem - they required over 1 meter of space behind the rear of the speaker, but since I did not have that much room, I ended up installing a cowling over the port which redirected the airflow downwards. This seemed to resolve most of the issue - the rest was remedied with correct speaker placement/toe-in.

I can now place the speaker much closer to the wall - i.e. down to 8 inches

My speakers originally came with a foam plug for the port that helped a little - it did not stop the airflow, just slowed it down a little

Personally - I do not use meters for two channel systems - I let my ears be the judge.

I do find a meter helps greatly with Surround Sound systems

Regards...
First of all, thank you all for the input. I spent a few hours moving my speakers around my music room, trying to move the speakers closer to the front wall, closer together, adjusting the toe, etc. I was able to get varying degrees of success but I still had massive nulls throughout the frequency range 80-250hz. I finally tried moving the speakers further out into the room. My reasoning was that I had good bass response below 80hz so I could lose a bit but hopefully still be within 3db of flat. I also moved my speakers further apart so that I was listening in an equilateral configuration. The results were better than expected. From 20-1000hz, I was within 3db of 70db. My only small null was at 800hz where the response was -6db down.
Sir

You have not taken the floor or the ceiling position out of the equation when you moved the speakers. You moved the speakers relative to the walls not to what is above or below. All speakers have a speaker floor bounce cancellation relative to the distance of the bass driver. You can have much the same cancellation from that same driver to the ceiling though at a different distance and frequency. If your monitors can be placed on the floor or on  shorter or taller stands or supports for testing this will give you more insight into a placement to reinforce the frequencys you are in search of. Tom
tboooe - have you tried putting the speakers against the 3ft wall?

If yes - did you still get dips in freq response?

What is on the floor? if it's hardwood - try a rug in front of the listening position.

Regards...
The rug will act as a comb filter and could add some benefit, a natural wool rug will be best..but will not help at 80hz. Tom