So your speakers will draw 2.16 watts at 90 Hz from the amp to produce 86.4 db at I meter, versus 1 watt if it were 8 ohms. So the low impedance in the range where the power is has doubled the power requirement for your speakers versus 8 ohm ones.
So, slightly over half your amp power is heating up the crossover.
Now lets take a look at an active situation. Lets take my speakers.
The bass units are each 8 ohm, since there are two drivers of 8 ohms, each directly coupled to an amp sensitivity is 93 db 2.83 volts 1 meter and that will take one watt of power. You will have to provide at least 8.4 watts of power to achieve the same spl, and more likely 10 watts.
But there's a major difference. You're using two 10" drivers designed to operate in large boxes. The Salon2s use three 8" drivers designed to operate in relatively tiny boxes. Even active, those particular drivers
wouldn't have high total sensitivity.
The
real issue isn't passive vs active, but the need for people to have full range speakers, instead of sacrificing 20hz extension for midrange efficiency.
Now even with that situation I still need to provide 750 watts per speaker, to keep things relaxed at concert levels.
You mention 750 watts but if they're not operating in the same frequency range I don't see how you can just "add them up".
That is why good monitor companies like ATC and PMC provide about 3 to 4 KW per speaker and that is with active crossovers.
Those are
not 3 to 4 kW - how can you realistically just add watts for amps operating in
different frequency bands? That's just silly because they will never contribute that amount of power at a given frequency. It's like having a 2kw amp from 20hz to 80hz and a 100w amp from 40hz to 300hz. You do not have 2.1 kW of power, nor does that really even mean much due to difference sensitivities.
You're right that active systems don't have insertion losses, which might mean less heat in the crossover, but that doesn't make them any more efficient a system either. More amps means more idling power losses too - you really expect me to believe five amps is inherently "more efficient" than one amp? Especially if one of those amps is wasted on a tweeter where you might only need 10 watts anyways to hit the tweeter's mechanical limits. And that also means you can't just
assume insertion losses affect total system performance either. So power is lost to insertion - the question is whether that
affects performance.
So if you quote sensitivity at 2.83 volts 1 meter, then a four ohm speaker draws twice as much power from the amp as the 8 ohm one.
Now if you quote sensitivity at 1 watt 1 meter, then the four ohm speaker will be 3 db less sensitive than the 8 ohm speaker.
So his speakers are 83.4 db 1 watt 1 meter is sensitivity.
Years ago all speakers were quoted at 1 watt, 1 meter, which is the honest watt to do it, The 2.83 volts 1 meter was introduced to pull the wool over the eyes of the consumer.
I
don't see how having a measurement that remains reasonably constant is inferior to a measurement which is frequency dependant....
They are 13 ohms between 2khz and 4khz - so they're 89db/w/m in that band. They're 8 ohm @ 1khz - so they're 86db/w/m in that band.
w/m is the one that puts the wool over the eyes of the consumer because watts are not a constant. With the correct amp, v are a constant.
The other issue is that power lost in the passive crossover is power not available to the drivers, and I was using that to illustrate the waste of amp power and pointing out that if it were an active design, then the sensitivity and spl would go up five to six db.
But... that's assuming the drivers would even appreciably... benefit from it. And no, sensitivity would not go up. You'd still be limited by the three very low sensitivity 8" woofers in the bass, and the 4" mid. The Salon 2s COULD be more sensitive if
A) They weren't made to fit inside small boxes (larger drivers, more sensitive drivers)
B) They didn't have an F3 near 18hz
The above are the real issues at play, not the passive crossover. Yes an active crossover means you could probably replace each of the ~10 ohm drivers a 4 ohm driver, which would get you some sensitivity (voltage) but wouldn't help efficiency (total
power draw)
The fact is, even if the insertion loss exists, it does would not change the sensitivity of the three parallel bass drivers, which we assume are the limiting factor. It would only change the sensitivity of in the frequency range carried by the other drivers, however that is assuming they're meaningfully more sensitive to begin with.
Revel won't say how much power those Salon 2 take, but probably not much more than the OP is driving them with. I would doubt he can give them enough power to solve his problem.
Revel rates them at 1000W power handling.