Subwoofer Question

This is so funny, Luke. Although I started this thread some 6 months ago, I just tried something similar to what you described this past weekend and it worked well. My sub isn't halfway between my listening position and the mains [it's closer to the mains] but results were quite good. Thanks for the input!

My room is 11' x 16' with mains along the narrow wall. Initially placed the sub next to the left main on the TV side. I discovered I had a bad low frequencey null right at the "sweet spot" listening position. SPL would vary by up to 6 DB by moving one seating position right or left of center. This weekend moved the sub to halfway between mains and seating position along the left wall and rotated it 90 degrees (it faces center of room). Reversed the phase with the mains and null is virtually gone. No more than 2 db difference across the seating positions.

Thanks a bunch Costrosk! I'll give it a try.

Gunbei:

Initially I'd leave the phase alone, and try to get to where you already are in integrated bass before fooling with it.

The process for setting phase on a sub is a little complicated and is best done with a test tone cd. What you do is reverse phase on your mains, then play the test tone at your crossover point. Sit in the listening position and have someone else adjust the phase on your sub until you hear the LEAST bass. That will be the perfect phase adjust when you return your mains to normal. Seems whacked, but it works. The other option of course is simple trial and error - try 90 degrees and see if it's better, etc. Use music you're very familiar with that has a strong bass presence, and you'll likely get pretty close. At the very least, you'll get to pick what sounds best to you, and isn't that why we listen?

Have fun!

chas

Thanks all for the great advice!

I just got a Bel Canto DAC 1.1 yesterday and the bass I'm getting now is unbelievable. Very detailed, tight and deep. I'm even more hesitant to move the sub now. I failed to mention that the alternative to leaving the sub where it is, is running 16 foot speaker cables. Maybe not such a bad option after all.

Wirehead, I researched subwoofer setup articles on the net and found several that advocated your crawl and listen approach. I may do it just out of curiosity. I have to know now! I'll make sure I lock all doors first. :)

Chas, thanks for the detailed procedures on matching gain and crossovers. How would phase adjustments play into this? Should I initially leave the phase at 0°? Or immediately change it to 90°, or just find what SOUNDS right?

Sugarbrie. Unfortunately, I don't have the option of placing the sub in a corner. I have dressers and an HT equipment rack occupying those areas. In my room, I have found your idea of lower crossover settings matched with increased volume to yield the best results. Higher crossover settings always muddied up the lower midrange.

PS: In most cases (not all) I find it hard to integrate a sub putting it on a midpoint away from the corners. Some will disagree with this, however may subs were designed to be put in the corner, so try the corner for a while and play around with the crossover and volume settings. Much better to have a low frequency crossover setting and more volume than vise-versa.

Try putting it in one corner behind one of the satellites. Try the right corner first.

Gunbei:

I haven't tried it (Luckily, I haven't had to), but in theory it should be possible to do. The theory is that the location of a properly set up sub, operating at the correct crossover, should not be audibly detectable. At least that's the theory, and that theory is completely contigent on the level and crossover frequency being low enough that localizing the source is nigh on impossible. In the real world (or more precisely, in your bedroom) results will vary, but to give it the best chance, you may have to run it at both a slightly reduced level and possibly lower crossover point. Since it sounds good where it is, just move it to the new location and try it out. Work the level down slowly til you feel it's either acceptable, or you hear the loss of the low end as just too great. If the former, you're done; if the latter, bring it up just as gradually as you went down, listening carefully to get it as close to level matched with your mains as you can. Once there, if the sub still doesn't integrate as well as you'd like, all you have left is lowering it's crossover point. Same shtick - lower gradually until you like it, or decide the loss is too great. With the lower crossover, you might then try bringing the level up a bit, but it might get a little bloated. It'll be tricky, either way, but... Theory says you can try!

chas

Gunbei: I was told there was only way to set up a sub: place it in your listening spot and then crawl around on all fours till you find the spot that sounds the best and that's where the sub should be. Oh, and don't do it when your non-audiophile friends are around. I hated explaining myself to a shrink.