I have a BAD room null...

[bayn]

So then why is that dip there at the crossover area?
It certainly looks like the sub quits early and the mains start late. Or is something else going on?
How is that corrected?

[fredk]

I agree with Wayne. Those sweeps don't look bad at all. You have two distinct dips, but they are not that deep at all.

Is your room height 8'? a 71Hz null at ear height (~4') would match with a room hight mode. I see that you have the same dip at 71Hz in your mains.

[Wayne A. Pflughaupt]

bayn wrote:

Wayne, what do you mean by "your bass management isn’t working well on the mains"? Does that mean the cross over isnt set right?

The mains should show a fairly sharp roll-out below the crossover point; 24 dB/octave is typical these days. Your crossover is set at 80 Hz, but notice at 40 Hz (one octave below 80 Hz) response has not dropped at all.

Of course other factors can come into play, such as the speaker's acoustic response in the room. Graphs comparing the mains' operating full range vs. with the bass management engaged would be the best way to tell for sure, but judging only from the graph you posted, the bass management for the mains doesn't look good.

Regards,
Wayne

[paulspencer]

That response is probably more offensive to your eyes than ears!

What you are getting suggests that the room has a decent amount of bass damping already. What kind of construction does the room have? Drywall light timber framed construction tends to act as a very large bass trap, and in rooms like this, the improvement might not be what you expect.

Looking at how left and right subs have an almost identical response, it suggests you might in fact improve slightly with some experimentation. Ideally you would place one of the subs in the listening position, then place your mic where you might want to put the sub. Now you can measure quickly in all kids of sub locations, but with moving the mic instead of the subs. This might give you some hints as to what you can try, and then start moving the subs and measuring again. If you can arrange your subs so that you can get one sub with a peak to match the dip of the other, you'll get an improvement.

Just out of curiosity, I merged all the charts together:



As you can see, above 65 Hz, all of the speakers have the same peaks and dips.

The mains have a 4th order roll off below ~120 Hz but it stops at 70 Hz. This makes me wonder if this is actually the response of the mains without any high pass. Are mains set to large?

[bayn]

Hey Paul,
The room is just a regular drywall room, it is my living room so it goes up to 8ft then gradually slopes to 9ft. Nothing special about the room except that it is open (completely) on 1 side to the kitchen and flows out to the rest of the house.

Unfortunately I don't understand much about sound orders and their rolloffs (I've read on it, but it never clicks for me ) But I think I see what you guys are referring too. It looks like my mains are trying to produce sound below the cut off and that should not be so.

The mains are set to small for just to clarify but I'm guessing that because they produce sound they can be interfering with the sub's, is that correct? I'm also unsure what you mean by "without any high pass" but if I can graph anything for you to help answer that then let me know.

Sorry guys, I’m trying to learn as I go

[paulspencer]

bayn,

A 4th order high pass will filter out lower frequencies and let higher frequencies pass through - not eliminate them, but add a slope. 4th order means 4 x 6 db ie 24 db/octave. So if set to 120 Hz, then it filters so that the response is -6db at 120 Hz, then it rolls off continuously below that point at the given slope. At 60 Hz, the filter is -30db (24 + 6). Of course, in an acoustic measurement you also get it summed with the acoustic response.