Re: Stereo subs - Do they rock or is it overkill?
I have been reading articles on this subject for years. Most are based on perfectly legitimate theoretical considerations. However, a simple experiment (which I have repeated many times with different systems and rooms) will solve the question for those willing and able to perform such an experiment.
Wire up a system this way and follow these instructions:
1. Preamp main outs to power amp to stereo speakers with limited or declining bass output below ~40 Hz.
2. Secondary preamp outs (or split main preamp output) to preamp with remote controlled mono/stereo switch (I used an old Adcom). Set preamp volume to unity gain.
3. Preamp outputs from secondary preamp to stereo subs. Set sub volume controls with 35 HZ Hz test tone and Radio Shack SPL meter to equal volume of primary speakers at 40 Hz (This is not too critical and can be done by ear using a recording of a musical instrument spanning these frequencies.)
4. Position subwoofers symmetrically to the outside of and at a slightly different toe-in angle to main speakers.
5. Listen to any familiar well-recorded CD in your normal listening position and switch between stereo and mono on the secondary preamp.
The actual frequencies necessary for producing the large improvement in sound which you will hear have experimentally been determined to lie below 25 Hz. I won't bother to describe the exact nature of the sonic benefit that follows from this setup nor will I engage in theoretical arguments such as those put forth in the Harmon white paper. Do this experiment and you will be convinced. Once you have done this, you will never consider using single or dual mono subs ever again. Every high end system should be set up this way.