Can I Correct <100Hz 20db dip in My Room?

[rkruz]

My subwoofer (SW) has several dips and peaks in my room caused by sound reflections from a large room with a tall ceiling. The worse is about 20db at 71hz. See the attached room frequency response. My 12 year old receiver does not do SW room equalization. The SW is behind the TV and I have no option to move it somewhere else but I have tried it in different locations all with terrible results. The subwoofer is 20 years old (Definitive, P1500, 250w, 15inch).
Can one purchase a subwoofer only EQ that will auto sample the room and smooth out response like Audessey would do but just for subwoofer?.
Would a Denon Receiver with Audessey MultiEQ XT 32 smooth out the SW frequency response shown?
I was considering a Denon AVRX4400H but would like to get a feel as to whether this <100Hz response is even in the "can be improved" range.
Your experience here is appreciated! thanks!

 

[Wayne A. Pflughaupt]

What you have at 71 Hz is a null. There is no correction for those except moving the sub to a different location, or perhaps a second sub at a different location. EQ will not help. You’ll find that a 20 dB boost will get you a graph that looks pretty much like you have now.

Regards,
Wayne

 

[JStewart]

Welcome to the forum rkruz!

Can one purchase a subwoofer only EQ that will auto sample the room and smooth out response like Audessey would do but just for subwoofer?.

There's one such device I know of that's been around a while that will do it.
DSPeaker AntiMode http://www.dspeaker.com/en/products/anti-mode-8033.shtml
A place I know of where it can be purchased is from Power Sound Audio. If you're not familiar, Power Sound Audio is a very highly regarded subwoofer (and speaker) manufacturer. Here's a link for that, https://www.powersoundaudio.com/collections/extras

Would a Denon Receiver with Audessey MultiEQ XT 32 smooth out the SW frequency response shown?

Yes.

I was considering a Denon AVRX4400H but would like to get a feel as to whether this <100Hz response is even in the "can be improved" range.

Yes it can be smoothed, but Wayne is right that the dip at 71Hz is a location issue that must be fixed another way. I would question if its even audible. Perhaps Wayne or someone else may have an opinion.
If you choose to go Denon be sure to check out Accessories4Less for pricing on a factory refurb.
https://www.accessories4less.com/ma.../receivers-amps/home-theater-receivers/1.html

 

[rkruz]

Thats all great advise. Thank you. I cannot move the SW to another location but I can point it differently to experiment for improvement and also play with the phase adjust. Now that i see the cost of the accessories it makes sense to get a receiver with Audeyssey MultiEQ xt32. Good points on the audibility of the null. Probably not a big deal in practice anyway.
Can REW pull EQ data from a Denon with Audyssey? thanks again

 

[Wayne A. Pflughaupt]

REW can only measure sound from the speakers. Thus it’s useful for determining what Audyssey has done, using “before” and “after” measurements.

Regards,
Wayne

 

[rkruz]

Id like to do that. My Radio Shack SPL meter has only 10db ranges. Im hoping that when used with REW that it extends past that since I have that 20db dip

 

[DonH57]

If the dip is due to a room mode null the usual fixes are to (a) move the sub, (b) move the listening position, (c) add a sub to "drive" the null, or (d) add a huge amount of room treatment (extremely difficult at 70 Hz). True room mode nulls are not amenable to EQ because they are caused by sound waves reflecting from a wall and cancelling each other. Amplifying the signal doesn't help: you change from 1 - 1 = 0 to 10 - 10 =0. And 20 dB is larger than most EQ systems provide; note 20 dB is a 100x power increase.

Adjusting the phase might help if if the null is due, or partly due, to the mains and sub being out of phase at 71 Hz. Otherwise, you really need to look at what you can do to move the sub or MLP, or add another sub to help counter the null.

IME/IMO - Don