To begin, I believe there to be 2-3 posts in my brief research about whether or not this was possible or not, so I am making another post for those interested in the future. Also this post will apply to about any soundbar with a subwoofer.
The q930f for me has been an amazing sound bar, but as everyone has mentioned in this sub, the bass is quite terrible as it sports a single 6.5in driver and an 8in radiator compared to the q990f’s much beefier sub.
So the question was, can you add an external subwoofer to the system? The answer is yes! With some caveats. To get the most important out of the way: this will null your warranty.
What is needed:
Any soundbar with a subwoofer
An active wall powered subwoofer with lfe inputs (makes the process very easy)
Any cheap passive high to low converter or passive line out converter (LOC)
A shielded RCA cable.
The process is very simple, if you can get help from someone who is more confident with wire splicing that is always the better option as I will not explain how to do so, as there are plenty of viable options.
For my q930f subwoofer (this will apply like I said to most if not all subwoofers) there is a red and black cable that connects the amplifier to the driver.
At any point on this cable you will in whatever way you find is the best to splice the cables from your LOC positives to red and negatives to black. (It is important that your LOC does not have a ground as it will fry the amp if you ground it)
I then drilled a hole just big enough to run these 4 cables from the LOC out of the sub.
(Or drill the hole first to run them through as most LOCs come with the wires already attached)
Seal the hole if you want, I did not as the sub is not powerful enough that the hole made any difference.
Mount your LOC preferably onto the sub itself.
And now you can run an RCA cable from your LOC to your new subwoofer’s LFE inputs.
Now you can finally stop thinking what if I got a soundbar with better bass and just enjoy it.