Originally Posted by tuxedocivic
With 2 oh the 8ohms, you'll actually be at 93db/m/2.83V, but at 4ohms. What you're not considering is baffle step losses will take down that single 4ohm woofer to 84db.
So is it fair to say that BSC will bring sensitivity down by 4 - 6 db then?
And it'll be sucking up twice as much power to make 84db as an 8ohm version. Think of it like this and compare it to my single 8" woofer 3 way that does 88db at 8ohms. If I am listening at the listening position 4m away at an average of 75db, that means that speaker is making about 87db average (6db loss per doubling distance). Ok, so on average it's using 1 watt. Suppose There's a 15db above average peak, that's 90db at the LP, or 102db at the speaker. That's 14db above the speakers sensitivity and my amp will have to make less than 32 watts to reproduce that peak.
Ok now lets look at the 4ohm load with 85db sensitivity (assume not full baffle step compensation). Again, at the LP you're listening at 75db average with a 15db peak. That's 90db at the LP and 102db at the speaker. Nothing has changed except that it's 17db above your speakers sensitivity and your speaker is 4ohms, therefore your amp has to produce just under 128 watts to reproduce that peak. Add 3db more dynamic range and your amp needs 250 watts! The poor little scan speak is gonna struggle with that. That's what an extra 2" of cone diamter can do for you. Or an extra woofer, your choice.
And sometimes getting good specs for power handling can be hard.
And most guys around here don't consider 75db average with 90db peaks at the LP at all good enough. I probably would be satisfied with that, but if you like action movies and to have a good time with your buddies over watching things blow up, a single scan speak 18w will not have fun doing what you ask it to.
Being in my fifties and having been too close to the front for many a concert I suspect that the 75/90 is probably typical, but crank it to 80/95 or 85/100 for the odd movie or music disc (when the wife's not around
If you were spending a couple hundred on a pair of bookshelves for you livingroom, I'd say don't sweat it, but it sounds like you want quality.
I definitely want quality - but am always open to finding great value.
Current 5.0 is three KEF iQ3 across the front and a pair of iQ1 for the rear - absolutely incredible value. Paired with a Rythmik F12, when I play Dark Side of the Moon m-ch SACD it sounds great.
I just want to make sure that whatever is my upgrade, is really and truly an upgrade all around.