I am completely confused on this XMax / XMech thing on the SI subs - the website and Josh seem to have different opinions!
The website says 22.5mm Xmax (one-way linear) and 43mm Xmech (one-way)
Josh's review (
http://www.data-bass.com/data?page=driver&id=46) says "The xmax is rated at 20.5mm with an xmech of 36.5mm (Confirmed by Klippel testing)." but then says "Manufacture's Xmax 23.5 mm" in the table, and "At what looked like maybe 60 or 65mm peak to peak the driver abruptly tapped the back plate. Xmech effectively seems to be closer to 30 or 35mm inward".
I have therefore been a bit paranoid about it lol
Hopefully the WinISD graphs are accurate and all should be safe!
And regarding another thing I'm paranoid about...
Looking at the table on Josh's site again (
http://www.data-bass.com/data?page=system&id=90&mset=97) (under the Static Graphs tab):
the 31.5Hz measurement seems to need 95v to reach excursion limits (XMech, going from Josh's text above the tables on the DB webpage).
If Watts = Volts x Amps, a 5000w CV5000 on a 240v 32amp Ring-main power circuit (breaker rating, as I understand it) would give 156.25v at full power, I think?? (5000w/32amps=156.25v?) Would this therefore mean that the following are max safe amplifier power outputs?
10Hz -- 126v x 32 Amps = 4032watts
12.5Hz -- 126v x 32 Amps = 4032watts
16Hz -- 119v x 32 Amps = 3808 watts
20Hz -- 113v x 32 Amps = 3616 watts
25Hz -- 109v x 32 Amps = 3488 watts
31.5Hz -- 95v x 32 Amps = 3040 watts
40Hz -- 126v x 32 Amps = 4032 watts
With the following being power supply / amplifier limited?
50Hz -- 189v x 32 Amps = 6048 watts
63Hz -- 283v x 32 Amps = 9056 watts
80Hz -- 283v x 32 Amps = 9056 watts
100Hz -- 283v x 32 Amps = 9056 watts
125Hz -- 283v x 32 Amps = 9056 watts
Or...
Do I need to take account of the resistance (Impedance) graph I posted a link to?
i.e. if Ohms = Volts / Amps, that means that Ohm / Volts = Amps, therefore the Impedance graph would indicate the following Amps required at each frequency to deliver 5000w (as modelled in WinISD to get the Impedance graph in Ohms) assuming a 240v power supply?
10Hz -- 4 Ohms / 240v = 60 Amps
12.5Hz -- 4.1 Ohms / 240v = 58.5 Amps
16Hz -- 4.3 Ohms / 240v = 55.8 Amps
20Hz -- 5 Ohms / 240v = 48 Amps
25Hz -- 6 Ohms / 240v = 40 Amps
31.5Hz -- 10 Ohms / 240v = 24 Amps
40Hz -- 15.2 Ohms / 240v = 15.8 Amps (stuffed)
40Hz -- 24 Ohms / 240v = 10 Amps (lined)
50Hz -- 8 Ohms / 240v = 30 Amps
63Hz -- 5.7 Ohms / 240v = 42 Amps
80Hz -- 4.5 Ohms / 240v = 53.3 Amps
100Hz -- 4 Ohms / 240v = 60 Amps
125Hz -- 3.9 Ohms / 240v = 61.5 Amps
which would then be fed back into the first calculations to give the following max amplifier outputs before the single driver tested by Josh was maxed out, using the Max SPL No THD Limit voltages from his table??
10Hz -- 126v x 60 Amps = 7560 watts
12.5Hz -- 126v x 58.5 Amps = 7375.6 watts
16Hz -- 119v x 55.8 Amps = 6641.9 watts
20Hz -- 113v x 48 Amps = 5424 watts
25Hz -- 109v x 40 Amps = 4360 watts
31.5Hz -- 95v x 24 Amps = 2280 watts
40Hz -- 126v x 15.8 Amps = 1989.5 watts (stuffed)
40Hz -- 126v x 10 Amps = 1260 watts (lined)
50Hz -- 189v x 30 Amps = 5670 watts
63Hz -- 283v x 42 Amps = 11915.8 watts
80Hz -- 283v x 53.3 Amps = 15093.3 watts
100Hz -- 283v x 60 Amps = 16980 watts
125Hz -- 283v x 61.5 Amps = 17415.4 watts
In which case my 4 drivers should be perfectly safe because they will each be getting 1250w at most, which is less than any of the power outputs above that were max safe limits of a single driver as tested by Josh??
And if I alter the last calculations and input the max voltages with clean THD rather than the Max SPL No THD Limit voltages, the following single driver figures show that with 1250 per driver I should be well under THD limits the whole time?
10Hz -- 57v x 60 Amps = 3420 watts
12.5Hz -- 53v x 58.5 Amps = 3102.5 watts
16Hz -- 58v x 55.8 Amps = 3237 watts
20Hz -- 80v x 48 Amps = 3840 watts
25Hz -- 109v x 40 Amps = 4360 watts
31.5Hz -- 95v x 24 Amps = 2280 watts
40Hz -- 126v x 15.8 Amps = 1989.5 watts (stuffed)
40Hz -- 126v x 10 Amps = 1260 watts (lined)
50Hz -- 189v x 30 Amps = 5670 watts
63Hz -- 283v x 42 Amps = 11915.8 watts
80Hz -- 283v x 53.3 Amps = 15093.3 watts
100Hz -- 283v x 60 Amps = 16980 watts
125Hz -- 283v x 61.5 Amps = 17415.4 watts
Man, my head hurts
lol