Sound bar in a box . . . can't understand dialog.


We have a large credenza in our bedroom that houses the TV, video gear and sound bar (a modest Visio) facing the bed. It's become our favorite movie theater. Think a 4'x3'x8' box with doors on front. The "booming" caused by the interior reverb of the credenza box makes any dialog unintelligible.  Tried moving it out a bit when open (a pain) as well as adjusting out lower freq.s and boosting treble. No luck.  

Any suggestions on something more creative would be much appreciated!

ALERT! Wife is an interior designer so anything that does not fit inside box is not acceptable. 
dancub
elevick
Thanks. The soundbar is currently connected to the Vizio via the optical link. The Vizio speakers are turned off.  Setup works fine as far as getting signal to soundbar and the soundbar is working. I'm pretty sure I'm dealing with box resonances with my difficulty understanding dialog.
Dan
I also have a Vizio soundbar, but luckily don't have any issues with my setup. Great inexpensive soundbars, btw.

I know the soundbar has rubber pads on it's bottom, but get some tiny self adhesive rubber feet, not flat ones, but round ones like this,

https://www.amazon.com/Self-adhesive-Clear-Rubber-Feet-Bumpons/dp/B001JAW454

Use 4 on the bottom of the soundbar. This will help minimize contact to the cabinet. Also, pull the soundbar as far forward to the front of the cabinet as possible. I would set bass and treble flat and see if the other adjustments, TVOL and TSHD, affect it any. Then try adjusting bass and treble.
Dan,
I think the soundbar has ports in it.  Block those and you might stop the boom.  You will lose bass.

It really stinks that almost all tv's these days have down or rear firing speakers.  They are all designed for wall mounting. Doesn't Vizio realize that most of us would gladly pay an extra $50 to get a tv with good built in speakers that are front firing.
elevick
Sorry to disagree, but I doubt his soundbar has ports. My Vizio is about 1 1/2 years old and it has passive radiators, as did all the ones in that series. Not sure about the very latest ones, but if they did have ports, I doubt he could get to them without some serious disassembly.
I'd be surprised if the Vizio had passive radiators only because they are typically more expensive to produce but I could be wrong, I'm not very familiar with the brand. The only thing I can think would be to put some type of damping material behind the soundbar...like a dark rolled up soft blanket or pillows or something to absorb sound that is bouncing around in the cabinet. Sometimes putting a speaker in a place like that is going to give you that tunnel sound. How much space is around the edges of the speaker and behind it?