The best/easiest way to answer your question is to measure the speakers in your room to see what they're actually doing response wise. It may state that they go down to 31hz in their specs but the actual in room response will be very different. You can use something like REW and a UMIK 1 to run a 20-20k frequency sweep and you'll be able to determine where to set up both your speakers and sub xover points
First, try to optimize the placement of your main speakers and your subs. I like to use the AM Acoustics room mode simulator. Try to keep yourself and all of your speakers out of the lowest room modes.
I am of the school of thought that a higher crossover for subs is best, especially given all the feedback from listeners who started too low. Up to 80 Hz is a good spot. In your case, this will reduce the load on your amps significantly, hopefully making up for the low impedance around 2 Ohms for your mains.
Next, consider sealing your main speakers. This will raise the -3dB point, but also severely reduce distortion and excursion in the lowest octaves. Clean socks work great here.
Lastly, the DSP control over the subs will give you an unprecedented advantage over pure main speakers. Leverage it, but instead of striving for flat, strive for a descending slope from 16 to 80 Hz, about 1.25 to 1.5 dB per octave. Then set levels to taste.
My advice above assumes you will be using a high pass filter on the mains, if not, you’ll need to still seal your ports, and then use measurements to figure out the best integration point which will probably be around 40 to 60 Hz.
Undoubtedly someone will get huffy about my recommendation about sealing a speaker which is ported. I say it as a speaker builder, and remind you that the procedure is easily reversible, depending on the condition of your socks.
Since the topic of a high pass filter has been mentioned I figured I’d share this, as it may be of interest to some - particularly Ayre Acoustics owners. I own an Ayre VX-5 Twenty amp. For that amp, and a few other Ayre units, a replacement "high pass input board" is available. Ayre makes a tweak to capacitors on the board to provide a high pass at 100Hz at the amplifier input. So the amp can feed the mains at 100Hz high pass, and the other output on my Ayre KX-5 Twenty preamp can feed a pair of subs. Evidently it’s common for Vandersteen owners using Ayre equipment. I’m getting to know a pair of Wilson Audio Duette with a pair of subs and I have a pair of these boards. I haven’t used them yet, but I expect they will be very handy - especially since I very much like 2-way speakers paired with subs to dial in the low end. I should be able to play with any 2 way speaker and should get a nice benefit from taking stress off the amp, and the woofer of the 2-way. The fact of the matter is, the Wilson Duette sound so good without the high pass filters I haven’t been in a rush to install them!
They are plus or minus 3 db at 31 hz. Ask Wilson what order the speaker is
2 nd or 4 th and stick with that Go around 37-38 hz. You never want overlap
at least 6 db higher for your specs are not flat at 31 hz try 73 hz kthey 38
on. A bunch of music , btw the Martin logan subs are not in the same league
a Svs 4000, or ultra 16 much better controlled ,the JL audio Fathom are the best of the bunch ,sealed are always more accurate then vented or passive radiator .
the ML subs are decent ,I am just speaking in absolute terms.
Unfortunately, my budget is exhausted after the McIntosh and Sabrina's so the subs are a carryover from my prior system. The remaining $$$ is for proper cables. Frankly, the way the room acoustics are optimized when the Wilson dealer was setting the Sabrina's up they were tricked into thinking the subs were on when they weren't.
One thing I should have mentioned, is that in-room performance of speakers has almost nothing to do with the specified or quasi-anechoic (Stereophile style) measurements.
Room gain is real, as are room modes which can move the bass output singificantly up or down. Setting a sub or crossover by published specs is really tough compared to doing it by measurement.
I found dual sub use with a two-channel set up to be more trial and see what works as opposed to a specific formula. So much depends on the equipment and room set up.
I'm also using a pair of Martin-Logan subs to augment my DynAudio Contours (which already have strong bass response). I wanted full effect on the very low end but I didn't want them to over play low end bass lines. After several attempts and some advice from Get Better Sound; I have them set up just in front of each speaker, laying on their side (they are bottom firing) so that they fire at the wall behind the speakers (set up for 13' x 11' room). The cross-over is at about 38-40Htz, phase 0 and volume is only at 1/4.
Basically, 80% of the time I don't even know they are there. They don't color the music be it Rock, Jazz or Classical until a bass drum or deep bass line is emphasized and then the bass sound is tangible. You can feel it without distortion; like a live performance. On something classical like the 1812 Overture; the cannons are a down right scary rumble. For an acoustic trio the bass line sounds like its in the room.
But that was the goal only wanted to capture the ultra low that the speakers couldn't reproduce. Also noted I set my system to direct without EQ or gain on bass or treble.
Putting in a sub and making it integrate well with main speakers and the room takes effort. I wrote about the difference between expectations and measurements here:
@upstateaudiophile My Wilson Duette are spec’d to play to 36Hz. I think my in-room response is better than that. I’m running dual SVS SB-16 Ultra subs. The way I have them dialed in is such that they do not draw attention to themselves. I have not gotten into measuring the room yet. I have a UMIK microphone and will do that. The thing is, when I turn the subs all the way down via the SVS app, I’m still very, very happy. In fact, on more than one occasion I forgot to put the subs back to their integrated setting. The Duette use an 8" driver I suspect is very similar to what is in the SabrinaX and they are really something for a stand mount 2-way. On more than one occasion they have made me say "WOW!". Your speakers are spec’d at 31Hz... of course that depends on the room.
In room measurements are the best way to integrate subs. The in room response of the Sabrina speakers is more complicated than the specified bass roll-off and subs can help correct it. I do not know if ARC/PBK is powerful enough for good measurement feedback or not. It certainly could be. With in room measurements setting the crossover point is easy with some experimentation, especially with speakers with decent LF extension, like the Sabrinas.
@upstateaudiophile placement is critical with Wilson speakers. I would recommend setting up and dialing it all without the subs first. Look into acoustic treatments as well. Introducing limited range bass traps and treating the reflection points was a notable improvement in my room with the Sabrinas. After you dial it in, start integrating the subs, if you still think you need them.
Definitely important points, I have a fully treated ideally shaped room and they were installed by the owner of the Wilson dealer. I marked their original positions in the room and made some subtle, perhaps 2 inch, changes. They are definitely in the zone of neutrality, positioned about 2.5 feet off the front wall, 5 feet from the side walls, and listening position is about 3 feet from the rear wall.
I took measurements based on advice above and also ran ARC Genesis. I currently have them crossed at 45Hz and it is sounding really good. Next step is a final decision on cables. I’m borrowing AQ Robin Hood Zero’s. I hope to audition some others from the dealer before making a decision. I read that Transparent is what Wilson has used in the past a lot.
Funny I had too much bass with my Sabrinas when I upgraded from Pass XA30.8 to Pass X260.8 monoblocks and was using Acoustic Zen Absolute Copper XLRs. No sub(s).
15ft x 13ft with 10ft ceilings. Large plush rug, GIK acoustic panels with Guilford of Maine acoustic fabric. Blinds on windows are down and made of wood, other decorative art on walls is dense fabric. Soon will have vinyl and CD’s etc on a wall shelving system that should soak up the early reflections from one speaker.
FYI, tested AQ Robin Hood Zero which sounded fantastic. Then just tried Nordost Heimdall 2 which also sounds fantastic but I cannot audibly tell a difference. For reference, I took some AQ bare wire 14awg and in excellent condition, and it sounded muddy and lacked detail. I know nothing about cables but it was pretty obvious. Wish I could try the transparent. I’m tempted to roll the dice for the Super or Plus cable given they supply Wilson.
I am absolutely blown away by how good the SabrinaX is.
@upstateaudiophile yes the Sabrinas are revealing and benefit from top notch cables. I like the Audience AU24SX speaker cables in my system. If you can locate a used set, I wouldn’t hesitate to recommend them. Great value.
For anyone who stumbles on this thread down the road, I crossed at 45Hz and paired with Transparent Audio-Super speaker cables. I tried Robin Hood Zero, Nordost Heimdall as well. The Transparent were the clear winners to my ear and like others have said, a sonic match for Wilson speakers. I felt the Robin Hood was a bit dry and the Nordost were very much too bright.