Subwoofers.... one 10" or two 8"?

oleschool -
Reasons for going with the SVS SB1000s are:
1) sealed design
2) 12 inch driver
3) rated into mid 20 Hz
4) small size
5) weight - I can move them around without needing a chiropractor
6) continuously adjustable gain & cross over as well as phase
7) line level and speaker level inputs
8) 45 day money back in home trial (free return shipping during that time)
9) 1 year money back on trade up
10) 5 year warranty
11) generally favorable reviews...both consumer and professional
12) great price (got a pair of SB1000s for <$1000 with free shipping)

Still messing around with settings but they look like keepers. Only thing I’m not crazy about is the black ash finish. Wish they offered a mahogany or cherry...even if it were veneer.

If your crafty applying veneer is simple really buy a sheet table saw router and glue .. All those seem like strong reason . I hsve s sunfire hsu 12 sealed and small i am gonna geab another used at some point gloss blk .. They are a little more like 750-1000 each .. Congrats . I know everyone has there opinions but i spiked mine starsound audiopoints 3 made a huge difference.. 

sorry hrs12 sunfire

@leotis -
I found that same procedure you recommend (setting sub's phase based on minimizing bass output at the crossover frequency while while main speakers are in reverse phase to sub).  It was actually in Sound & Vision and submitted by Robert Harley as I recall.  I didn't do the out-of-phase-on-the-mains part but did try maximizing dbs at the crossover frequency using a tone generator.  I will repeat the procedure to confirm but it seemed like a large change to my almost 0 degree initial phase setting was needed....going to 140 degrees! Both channels ended up at the same phase value and I was not trying to read the actual setting at that point...just going by ear with what gave the loudest sound.  Anyway, afterwards,  I was not very satisfied with overall impact on music.  It seemed like soundstage had collapsed and (lower midrange?) was weakened.  At this point, I'm inclined to agree with Erik that this method may have unintended consequences.  Based on what else I'd read about phase differing across a range of frequencies this is, perhaps, not surprising.  I'll probably repeat the experiment BUT I suspect setting phase is going to be trial and error based on the overall effect on the music and not just max db at the crossover frequency.

If you sum the signals from the sub and main you get +3 dB.(less after room interactions) If you cancel the signals with reverse polarity you get -40 dB. Much easier to hear! Method works best when the sub is close to the speakers. If sub farther away then differential distance from sub and main to different points in the room varies more, and result becomes more hit or miss. Then trial and error may be the best you can do. Maybe you are referring to Harley in Absolute Sound. http://www.theabsolutesound.com/articles/subwoofer-basics/?page=3

leotis - YES, RH of TAS. I might have muddled things together having read a couple of pieces about that  method including the one at the TAS link you provided.  I think RH contributed as well to the Sound + Vision article I read.  Did see his name...maybe in the comments section.  

The subs are located right next to the main speakers so that’s not a complicating factor. Some say not to go this way, others recommend it. The folks at SVS were okay with it as they say their subs do not have to be "boundary loaded".  They appear to be giving acceptable performance in this position and just need a bit of tweaking. I’m inclined to repeat the out of phase/phase setting experiment though as I mentioned results after the first attempt were not "ideal" in terms of overall impact on the music.

Hi Leotis, 
The links you posted above are interesting and look as though they'll be helpful to me (once I can get my DIY subs back online, anyway - modifying their cabinets and amp right now), Thank you! 

To anyone interested, I repeated the out of phase/phase setting experiment using the on-line tone generator posted above and a Radio Shack SPL meter positioned approx. ear level at the listening position.
I ran measurements from 200 to 10 HZ for the Silverlines alone with volume at 200 Hz set to 80db. Observed values generally less than 70db for 50 Hz and lower (a slight bump to 70 & 74 db for 40 & 35 Hz, respectively). Decibel levels at 80 Hz were virtually identical (i.e., 82/83 db) for 0, 20, 80, 100, 120 & 140 Hz. At 160 degrees, a slight reduction to 80 db was observed. A value of 77 db was measured at 180 degrees. I did not find a huge null created by running the subs out of phase to the main speakers. I wonder if this has to do with the great disparity in speaker sizes (one 12" SB1000 driver vs four 3.5" mid/woofer drivers in the Preludes) or if it is due to "reinforcing" room effects. I did listen to quite a bit of music afterwards with connections properly matched between subs and mains and with the phase now at 180 degrees. Did not notice any of the negative effects previously reported with phase at 140 degrees. Possibly the ("sub") bass was a little better at 180 than at 0 degrees but it was very subtle if not a placebo effect.

You've GOT to be kidding that you're even considering an 8" sub-woofer.  There's no replacement for displacement and even with a 10" driver, you're marginal on the deep end, which is where subs are supposed to operate.  There's a reason they make 12", 15" and 18" bass drivers...

There is also a very good reason for running two subs vs. one.  With just one sub running, you're going to have an uneven low frequency response through your room due to room resonance.  With one sub running, move around the room while music with good deep end is playing.  You'll find there are null and peak spots in different places.   But those will also depend on where the sub is.  With two (or even more) subs, you'll have that tend to even out depending on where you place the subs in the room.

Go for the two 8". They will compliment the drivers in Mirage OMD-15. You want a seamless integration of components that work together to accomplish your goals.  Rel - especially older models will sound more musical. JLs are solid.   

I initially never believed in subs until I read a paper from a professor at MIT on how humans process frequency response. Generally the standard - it lays within 15hz - to 20khz, however there are ambient environmental vibrations that other nerve endings in our bodies / brains pick up that also affect how humans process sound - Therefore extending this actual frequency response to lay within the 10hz - 120khz range.  

If the goal of the audiophile is near perfect sound replication then ... how does one achieve the goal? There are no speakers that can achieve this task alone, and the ones that are somewhat close in one way or another, cost as much as if not more than a house.

I realized that the most economically way to work towards the goal was to invest in Subs as an extenuation of my speakers limitations. I make this obviously sounding statement because I have seen systems where there is overkill that produces Noise, not music. So my two 6.5" mid/bass drivers on each speaker are complimented by a 10" sub driver on each speaker.   
 
There is nothing simple about a 2 channel system. The difference is in the details. Work within your means, enjoy this hobby.