No bass on B&W 800D2

@seb_audio 

I looked at the power specks for both of your speakers.

The high end of the range for the 800s is 1000 W and for the 802 first generation it's 500.

To me that suggest your under powering the 800s relative to the 802s significantly based upon the specificatio…. The 800s really need a lot more power.  You're using the 4 ohm connection and who knows what that could be doing. Using 400w but I'm not sure how the speakers interpreting that.  Have you tried connecting to the 8 Port on the back of the speakers?

@seb_audio 

Those speakers do produce a lot of bass when working correctly.  And you’ve run all the usual checks.

They are sensitive to room placement.  Try moving closer/farher from the wall.  And I mean move them 10 feet from the wall to a stupid position to see if you have a null.  
 
if you have them, put a thick “bass trap” behind the speakers just sitting on the floor about two inches from the wall to see if your getting a null.  If not handy, use two very thick couch cushions for a test.  (I have to use a bass trap behind my subwoofers/main speakers due to a weird room configuration.)

They’re used so see if something is jammed or fell into the port (eg foam plug was out in and someone pushed it in)

 Try toe while moving around.  I wouldn’t think this is it, but you’re moving them around, so why not.

The real test is to buy a room microphone and go run REW test from your listening room.  I did this extensively before treating my room.  The mic is cheap and the software is free.  

Or maybe you’re a bass addict.  I have 800D3s and need two big SVS16 ultras to give me the bass I like.  I ran REW and it showed all was good but I wanted to feel bass in my chest.

Thank you, @davetheoilguy !! Funny that you have yours paired with SVS subs as well. I liked the sound of them better than the B&W sub i had before. 
 

I have a measurement mic and will measure with REW this week. Will post graphs here. 
 

do the woofers on your 800 move noticeably under load? Mine barely move while my subs are going nuts. I’m not expecting the same level of excursion on the 800, but more than nothing. 
 

Since the speakers are in the same spot as the 802 I guess it’s pretty close to an A/B test and I still doubt I’d all of a sudden be sitting in a null. Subs are in the same spot too. I am crossing them over higher and dialed them up by a few db and I’m still not happy with the level of bass I have compared to what the 802s produced. 

@seb_audio 

”do the woofers on your 800 move noticeably under load? Mine barely move while my subs are going nuts.”

No, not really.  And yes my 16ultras are visibly moving. But keep in mind SVS specializes in subs and has big movement (and air) because it designs purpose built woofer drivers.  You can’t have big movement like that and multitask into the lower midrange like the 800s do.  It’s completely normal.

Do get a flashlight and look for foam (or a sock) or whatever stuck in your speakers.  Sometimes, with age and poor handling it could have even fallen down from where it is mounted.  This would prevent proper movement of the 800 drivers.

My money on the issue is a weird null for no logical reason (it’s called acoustic “theory” for a reason) or, slightly more likely, you’re a bass addict.

It’s a fatal disease.  Chronic.  The only cure is MORE POWER.

Maybe, just maybe one of the speakers is wired inverted.

Try swapping + and - on one speaker only and see if it changes bass.

Then do the same on the other speaker only.