Sub Woofer set up

https://www.soundstagenetwork.com/measurements/silverline_sonatina_iii/

Your mains start to lose output at just 100Hz anechoic (they are also decently v-shaped, unless you listen at low levels).

So yeah, all speakers should be set to Small and the crossover set to where they fall off in room (60Hz-80Hz for your mains). For those of you that do measurements, this would be the -6dB point in-room when playing a loud test signal. 
 
You don’t want both speakers and sub playing, as they will have various phase cancelations across the shared frequency range. This should be done if you truly have immense localization problems and don’t care about the phase cancelations.

Hmmm. What about the option to set all speakers to large and sub to yes?

@millercarbon 
 
Then you get the phase cancellations that I mentioned.

Hi
I missed something… I suspect you are using some signal processing, right?

I had a pair of Sonata IIIs sans sub.

later I added a velodyne DD15.

I then chose to go without the HT aspect using the sub simply to augment the Sonatas lower end.

I employed the DD 15s room EQ and found the best spot in the room to locate the sub. long story short… eventually I changed the auto settings the sub’s mic and eelctronics chose during its outlined installation and went with taste instead.

there was not a ton of desparity between these settings, but I did alter settings from what the subs’ EQ decided for me to what I chose.

the info provided here above is great. don’t mnisunderstand me. I simply wanted to interject that maybe once things are set accordingly to what ever acoustical scheme seems to work on paper, your input matters more, IMO.

during HT setup I went with the LFE only input…. later I went using the stereo inputs as fed from my preamp.

the best situation would have been for me to have bought two subs probably.

next time I will get two of them.

often getting bass issues corrected usually means adding bass traps as bass corredction can only do so much.

best of luck. enjoy

Thanks everyone for their input as this has been very informative. I will set my all my speakers to low for now. What do you suggest I should set the crossover frequency since their range is 25 Hz-28KHz (+/- 3db). Crossover points are 200/2000/4500 and tweeter uses 6db first order filter.

Uhhm, I really think you should read up on subwoofer material. Soundoctor.com is a really good informational site. Using the LFE output is not generally recommended. Explained by soundoctor.com.  it's a lot of reading and understanding but worth every minute spent there and it's free.

@gillatgh

Zero issues with LFE.
Taken directly from your linked website:

In a living-room sized room, the most desirable setup is to run all the speakers as SMALL, and send the fully MANAGED BASS (NOT ’just’ LFE) to the SUB(s)

@cavy

As I’ve explained, unless the measurements are off (they are only 100% accurate down to ~100Hz), your speakers likely don’t hit 30Hz at high outout; A crossover isn’t a hard cut either, it’s a roll-off in both directions, I would try 60Hz to start.

Thanks to all

60hz is a great place to start and add another sub if you can