Originally Posted by ntxoa
The analog sub signal seemed early relative to the HDMI.
My latest Oppo audio settings have the sub distance at 0’ and all the other speakers at 50’. That seems to delay the analog sub and get things to sync better.
Other setting tweaks - I changed all speakers to large, sub trim to +10 db, and crossover to 80hz.
Before, when I had speakers set to small, I couldn’t set the crossover higher than 40hz because I would get low frequency from dialogue coming through the sub.
Good tip on sub distance. I have mine on 12 feet so I'll play with that. I'd be surprised if the other speakers settings other than large/small have any impact on the sub. From what I read and posted above having the other speakers on large means the sub is getting a full range signal so crossover frequency setting in Oppo has no impact. No matter what the settings your hdmi from Oppo to the Samsung K950 sound bar will always be full range.
Also I'd advise against sub trim over +5 give the sine wave performance posted in the graphics above.
My guess at optimum setups for your situation would be the following:
1. Large speaker settings so full range signal to your subwoofer module. I'd then set the subwoofer module for 40 hz on your sub (lowest setting) with no phase flip. This should give you 24 db slope which should cross nicely with K950's steep rolloff at 24 hz. Now you will have room modes that effect the bass and you could have suck out issues or peaks from the room. Placing both subs will be important for room modes and you might want to up your extra sub's crossover point from 40Hz if the room is not boosting 40 hz, but I wouldn't think higher than 50 hz.
2. Small speaker settings on Oppo and you set its rolloff at 40 hz, maybe 50hz if room not supporting 40 or so well. This will be a 12 db rolloff and you don't want your sub set at 40db as you end up with crazy 36db rolloff.
Here set your extra subs rolloff as high as possible so it has negligible impact. However I would try the phase invert switch for sure.
The 12db rolloff will defintely help ameliorate the leanness we see in 40 to 80 hz range for the K950.
On paper these would be the two best approaches. You did not mention the settings on your extra sub itself so I'm wondering what you have it on.
I'm going to play with my setup some more and see what I find.
My tower speakers whose subs I'm using has a scant 6 db per octave slope when setup as designed (the first order slopes create no phase issues). They are 80 hz, 6db slope and you hear a lot of music coming through the subs needless to say. Your subs at 40hz with just 12 db slope should be fine even if they are not designed to cover into the midrange. If you're set at 40 hz that means they are down 27db by 160hz. Your sub is designed to be set as high as 180hz with 24 db slope. So around 160 hz with the Oppo only doing the slope you're down nearly 27 db more than your extra subs. By 200 hz you then have a 36db per octave slope so should not be possible whatsoever to bleed into the midrange. By 640 hz you are down 51 db plus another 51 db from your extra sub if it were set at 160 hz. In contrast my tower speakers would be down just 21 db or so at 640hz to your 102db.