I read all that, but some people have said that without the ELF rackmount deal, it pretty much sounds like a bass cab. It's in a pawn shop, so I'm not sure how cooperative they would be as far as letting me mess around with it.
That's why I said try before you buy. If they want to sell it, they will let you run a demo. Maybe they will refuse. You won't know till you ask.
By the way, what does a bass cab sound like? I am confident a 10" ELF sub will not meet my definition, but maybe you will think it sounds great.
I found it impossible to use a S15D full range. My perception is it was all mids with no highs or lows...but lot's of people love the S15D. So again, maybe you will like it.
I have read that it's a very mediocre sub, used as a traditional sub
Probably considered mediocre because of the very limited SPL capabilities. However, when operated as designed, IMHO it should sound very good. It just can't play loud and low.
Who wants 8hz at a gig?. Plus it apparently takes several 18" subs to get much usable volume out of ELF, so how many 10" ones would it take?
If I remember correctly Bag End's position is running ELF/INFRA to 8 hz gives better phase response. Not sure how much value there is in this as the human ear is not particularly sensitive to phase variance.
I built a Bag End system in the 90s that used four of the S18 Compacts powered by 1600W total. The compacts were custom order and half the depth of the standard S18s. AFAIK they had a 3-4dB lower sensitivity rating. The point of the system was to cram a full rock band with instruments and PA into one of these. I chose compacts to ensure the system would fit, and it did (barely).
If I remember correctly, I thought the system sounded best with the subs cut off at about 40hz. If I ran the subs lower, the system volume was too limited and the ELF processing was audible with the system pushed to it's limit. I believe the processor uses a variable HPF under the term Concealment. If you push the system to far into Concealment you can hear the low end thinning out.
The system sounded good and I considered the level usable. We did dances in bars and outdoor gigs, but the system was not intended to provide what we normally consider as concert level SPL. I think a single JBL VRX918S would probably play louder than all four of the S18s. The only real criticism I heard of this system was we sounded too much like a CD...which I was okay with, since that was what I intended.
Regarding how may S10s you would need for a rave in your bedroom. We assume the SPL goes up 6dB each time we double the speakers. How low and loud do you want them to play.
If you want a 115dB at 20hz, you need + 24dB (115 - 91 = 24). So you will need to double the speakers 4 times to get in the ball park. Since the 6db increase is not perfect, lets double 5 times just to be sure.
1 = 91dB at 20hz
2 = 91 + 6
4 = 91 + 12
8 = 91 + 18
16 = 91 + 24 = 115dB calculated
32 = 91 + 30 = 121dB calculated...real world measured SPL will be lower. So the exact answer will be somewhere between 16 and 32 S10s for 115dB at 20 hz.