What is wrong with a sub?

davidgwillett,

You also need to keep in mind that part of the benefit comes from relieving the mains of the low frequency duties. This requires a crossover, preferably active, to limit the impact on the sound. Also, don’t go too small on the main speakers. I am a believer in Richard Vandersteen’s theory that your main speakers should be reasonably linear to one octave below the crossover frequency (so 40hz with an 80hz crossover). In the real world, your main speakers should have at least a couple of 5.25" drivers each or a 6.5" or larger to get proper integration.

And yes, the optimal position for speakers for best bass is usually different than the optimal position for imaging.  

@mcreyn - that was a bit Greek to me.  
What I have now:
300B SET (CAD-300SEI) with Watkins Gen 4 speakers on each side of my desk 8" high stands, REL i7(? small one) sub under desk to my left. 
The sub hooks to the amp speaker posts.  I'm pretty satisfied.

New amp is A/B 60W/channel and Vandersteen 2ci (which the SET amp can't push well).  This will go in a larger room with cinder block walls.  My plan is to get a larger REL sub and again hook to the speaker terminals.  I was also thinking Klipsh Forte instead.  Some of the Martin Logan looked good, but were pricey and had subs built in.  That kinda got me thinking why not separates (subs).

I had considered the "new at the time" Forte IIIs but I already owned two RELs so I went with Heresy IIIs (about half the cost of Fortes). I like the fact that a sub or two (or four) allows you to tailor the bass to the room’s quirks, and multiple subs work together to tame some room issues. "Full range" speakers aren’t gonna allow you to pull the low bass driver out of the box and put it somewhere else with its own controls, although that’s exactly what happens with a good sub. My RELs sound great with the main speakers running full range to their 58hz or so bass drop-off point, and these speakers display a nicely accurate bass to their limits, so overall it’s very satisfying and musically right. I tweak the sub levels a little here and there but very rarely need any EQ beyond that.

Better ones are damn heavy.

Subwoofers are absolutely audiophile. I think at times they get a bad rap because people don’t take the time to set them up correctly and all you hear is bass that sucks the detail and music out of the lower octaves. A properly set up subwoofer should simply extend the bass down to the lowest frequencies and you shouldn’t “hear” it - it should just sound like your mains play deeper. It also adds a nice tactile feel to your music, which is present in the live recording session.

There are are many benefits of a sub and mains over just mains. First, few mains can get as deep as a subwoofer. Second, the optimal place for a sub doesn’t always correlate with the location of the mains. Third, you can relieve your mains of sub duty which can improve clarity and give that duty to your sub which is made for it.

PS: If you go with a sub, use DSP so you can adjust the curve to account for peaks and valleys in the sound due to room effects. Or better yet, use multiple subs. Two is great. Four is better yet. 😀