Best place to put a single subwoofer?


I know there are many opinions regarding subwoofer placement. I have had multiple subs (4) all in the same listening space. Way too much! I have had matched pairs hooked up in stereo. Right now I own only 1. It is part of my dedicated 2 channel music room and not a theater system. I have a pair of MBL 101e Mk2's which are excellent speakers IMHO, and they produce POWERFUL bass in their own right. However I am a bass freak (as noted above), so the harder it hits the better. Plus I tend to listen to a fair amount of rock music which I like to play loud, (hence MBL 101e's). Right now I have my sub positioned dead center between the two Radialstrahlers and it does ok. But I feel as though I'm missing something and that I ought to do something to increase performance, although I'm not exactally sure where to go with it. Not too many places I can move it to, but input and suggestions would be much appreciated. I have tried moving it closer, and then farther away from the wall but have not noticed any dramatic improvements. What about bass "suck out"? Could I be having some cancellation issues? What things would you Audiogoners do to improve on (already good) bass performance?
martinmobile
Martin,

Your speculation about suckouts (due to room interaction) seems like a good place to start. Given the low end capabilities of the gear that you're using, I'd guess that room issues are the most likely cause of your disatsifaction with the low end performance of your system.

It's possible that you can position a single sub to address such problems, but that's a time consuming porocess of trial and error, and there's no guarantee that any position will provide a satisfactroy result. However, life is easier when you have the right tools. Either a stand alone RTA unit (like Room Wizard) or a RTA sub-woofer manager (like the Velodyne SMS-1 or Audyssey SVS) will provide a visual readout of in-room bass response. IME, this assistance will cut the effort significantly .

Or, you might see if you can find a dealer who'll allow you to do an in-home demo of any high quality HT pre-pro equipped with Audyssey (or similar) digital room correction. Substitute the pre-pro into your system in place of your existing pre-amp and A-B the system with Audyssey in and out of the loop. If Audyssey fixes the problem to your satisfaction, you can then proceed with whichever Digital Room Correction system best fits your preferences. There are a bunch of different DRC units available for you to choose from.

Just one more way to skin this particular cat.

Good Luck.

Marty
Were I placing only one I would start out near middle of the room (though not exact, but off by a foot ot two) near against a side wall. Then take measurements at the seat, moving the sub up/down the wall length up to a few feet one way and the other at one inch increments searching for best room integration. And if not getting desired effect then up to six or eight inches further away from the side wall at one inch increments, again going up/down the length a up to a few feet.
Oops! Forgot the first step before moving it around: adjust its phase to match the mains first. Final position then adjust the volume and cross-over to best integrate with your mains. You may still need to adjust the phase again.
IME, the two simplest and most effective techniques for subwoofer placement that require no equipment other than a SPL meter are:

(1)

1. Place the sub at the listening position.
2. Walk around the room and listening for the location where the bass is *consistent* across low frequencies. You can do this by ear or with an SPL meter.
3. Once you find the location in the room that has the smoothest frequency response (by ear or meter), place the sub in that location.

(2)

1. Flip the polarity of either the sub or the mains (but not both).
2. Play a test tone at the crossover frequency.
3. Use an SPL meter to measure the output level.
4. Adjust the sub position (or digital delay, if you have that capability) until you MINIMIZE the SPL at the listening position.
5. When the sub is in place, flip the polarity back so that the sub and the mains are the same polarity.

IME, it is usually best to find the general placement with procedure (1) and then go on to make fine adjustments with procedure (2).

The only caveat I would make about the above procedures is that neither one guarantees that the sub will be time aligned with the mains, and IMO, the best subwoofer setups are time aligned. But this is a controversial opinion. If you are interested in subwoofer time alignment, you can read about it in this thread. If that's too much information, then just following the procedures above should get you in pretty good shape.

Good luck.

Bryon