Subwoofer Crossover Question

REL subwoofers are easy to set up and blend with your system. Run your main speakers full range and blend the RELs into your speakers. I would not be concerned much with specs because the room and overall system plays a big part in the balance. This really needs to be done by ear. Read your REL owners manual.

Not what you want to hear perhaps, but if your speakers are only down 6db at 23hz I question the value of using subs at all. There is a lot of information 'down 6db at 23 hz'. Now if you really meant down 6db at 32hz then subs really can help. There is little information much below 32hz and, as Rrog mentioned, your room and set up plays a major role in bass frequency response.

What subs can do really well though is help smooth out the bass frequency response. This is accomplished by placing the subs in other locations than the mains and, often out of phase as well. The ear is not as sensitive to the frequency variations as one might think except in a gross manner. I would (and have over the years) use a SPL meter (Radio Shack has one which will do well enough and its cheap) and a test record with 1/3d octave tone (such as produced by Stereophile), placing the SPL meter at the listening position, charting the FR of the mains at this location, and as Rrog suggested running the mains full range and the subs crossed over as low as possible. The object then is to flatten the bass FR response by either/or/and moving the subs, changing the cross over points, and the volume of the sub, remembering that those subs can be effective placed anywhere in the room that they might add/or subtract to the bass FR. They don't need to be up front with the mains, in fact, in my experience they can sound quite good located on side walls.

FWIW if your speakers were down 6db at 32 hz I would probably start out with the cross over set at 60hz. In theory at least as the frequency response level doubles (i.e. 32hz to 60hz)and the power level double (i.e. down 6db to down 3db is a doubling of volume) so the suggested cross over point in theory would be down 3db at 60 hz. But experiment, you want to keep the cross over point as low as possible. If set too high the subs will start introducing higher frequencies into the sound and screw up things imaging etc. Not too effective a way of explaining this I think, but hope you will get the idea. There are some excellent books available on this subject.

I agree. I run my Maggie 1.7s full range and my SVS subs crossover at 40 Hz. That seemed very low to me, but it was a factory, recommendation and it works beautifully. I have a Antimode on each sub and I run them is stereo. That made a big improvement over mono. For a while you will likely have them running too high and too loud, but you will find music with not much bass sounding better due to imaging. You will have a good time exploring new limits in your system. Many opine subs would sound better if driven from the power amp, not taking away any power, but making a better match to the amps' own sound quality. If you don't go with room correction, this is another way to play with the sound. Enjoy!

Well I just re-read your original post - I don't know how I missed your description of the spec's on FR which have your speakers down 2db at 28hz and 6db at 23 hz.

This is a remarkable FR! Unless you are trying to correct room response issues by locating the subs in locations that will fill in nulls heard at the listening position I would think that subs will do more to screw up the sound than improve it. -2 db and -6db isn't much actual volume wise, and would be considered a very shallow slope. That assumes however that you want a flat FR. Certainly if you are trying to increase/elevate the bass response with out changing the frequencies above say 100hz then the subs can do it, but keep the cross over point at its lowest, or close thereto. Have fun.

Newbie,

You make some excellent points but the spec on his speakers
are +/- 2db down to 28hz so they could not be down 6db at 32hz.

With that said I concur with your following statement.

"Not what you want to hear perhaps, but if your speakers are only down 6db at 23hz I question the value of using subs at all."

OTOH, if the OP uses the speakers for Home Theater or listens a lot to organ music.....

At this point it would be helpful if Matt would tell us what he feels is missing.