Subwoofer Crossover point ?
 

Hi all just bought a REL S812 to compliment my Sophia 2’s. Any opinion on the optimal crossover point ? I guess I should be somewhere in the 40hz - 60hz range. Any experience from owners using subs ?

If you are using an active crossover, one advantage of using a higher frequency is that you can take the extra load out of your speakers and amps and let the subs do what they do best. You can play around with different crossover points and then decide what you like best.

First of all absolute congrats! Seems like an excellent sub with the possibility of stacking down the road. First I would try running the Wilson's full range. This is what Wilson recommends and it works surprisingly well. All Wilson speakers are very robust being almost impossible to overload in the low end and you will hear the active HP to some extent. I would experiment both ways and try 50 Hz LP only first, running the Wilsons full range, but I suspect you will like the LP only.

Can you ‘measure’ your room with REW? If you want data, that is the way to get it. If you want to feel it, run your mains full range and dial your sub in starting at a low crossover point (35) and raise it from there.

I vote for measuring and getting data.

JA's measurements shows the tuning frequency of the port to be 26 hz and an almost +6 db hump at 50 hz so I would start in between the two and then slowly work my way up. I would probably start at 35 hz. Soundstage's measurements don't show a drop off until below 35 hz.

Run your speakers full range and use REL's preferred method of connection (speaker level). I've owned two REL subs in two different homes and in both set the sub below 40hz. You want to feel, not hear the sub. Above 40hz you run the risk of making the mid-bass muddy. If your room has a bass hump you can set the phase to - (minus) and reduce the hump.

Thanks guys that's really useful advice. I don't have a receiver so have connected it with the high level Neutrik cable from the amplifier speaker terminals so will be using the Wilsons full range. Still breaking in so have crossover around 70hz and half volume and it's loud - impressive, not boomy...but well over the top ! I will dial it right back after a few more hours and 35hz sounds like a good starting point.

What I find slightly frustrating is the advice to 'dial it in by ear'. I don't know how the studio truly intended any given track to be heard and I like bass so risk over doing it. Would rather start with measurements and make slight adjustments from there.

I have a feeling that getting the volume right may be more of a challenge as a crossover around 35-40hz makes perfect sense.

Listen to your speakers with the sub off and get a good sense for their bass, if the sub starts to smear or cause mid-bass to lose detail you've gone to far with the level adjustment.

I just attended a demo of the new Wilson Audio XVX this past Saturday and Peter McGrath was there and commented on the use of subwoofers with Wilson speakers. He said that generally, with most of their speakers, they crossover at about 32hz (presumably for their full range speakers). I'm not sure this is applicable to all their speakers (e.g. Sophia 2) but it sounded like a good starting point.

Subwoofer Crossover point ?
 

Most suggestions are rules of thumb. If your main speakers have pretty flat bass but roll off at some frequency, say 40Hz, blending a good sub in at 35-40 makes a lot of sense.

What if in your room, those super main speakers are not flat down to 40 Hz? Let’s say they show a big resonance bump at say, 60Hz, you might want to take advantage of crossing them over above this frequency and using your flexibility in sub placement to avoid that resonance at 60Hz.

That is why I prefer to know how my room measures after I have done the best I can with main speaker placement. I can dial in my sub much better with that data. My ears are not as good as the microphone.

Good luck no matter what you decide to do.