I myself would go with the 15hz tune. You will gain a few more db's of SPL from 15hz to roughly 30hz. And from there you are 1.5db hotter than the 12hz tune.
Down low the 12tune wins by a huge margin. At 10hz you have a 5db gain but at 13hz they are the same. You will have lots of room gain also to aid both.
16cuft 15hz tune Hpass at 14hz 2nd order 550watts to hit Xmax and hits 113db at 20hz.
16cuft 12hz tune Hpass at 12hz 2nd order 450watts to hit Xmax and hits 111db at 20hz.
You will enjoy most of your movies bass from 20hz and up. But maybe you want this extension verse the 20hz db.
I am looking at spl, excursion and applying wattage.
SO I am sure we are on the same page but you are only looking at the Transfer Function Magnitude screen.
You simulation still is different than mine. Why do you have a Hpass of 20hz on the 15hz tune?
Here is my simulation with your driver file and EQ. The Xmax is 22.5mm on the SI website not 23.5mm. I also only took the drivers to Xmax in the simulation. 715watts for the 15hz tune and 550 watts for the 12hz tune.
I believe the Behringer DCX2496, Mic2200 and a few others out there work down to 10hz just fine for Hpass.
AFAIK peak limiter is not a good way to protect drivers in vented boxes because they may unload with power well short of the limit. Both 15 and 12 Hz models I tried needed HPF.I want to ask the exact same question. So I hope everybody doesn't mind if I ask it in this thread rather than start a virtually identical thread.
I have a couple SI HT18D4s coming. Originally, I was planning a 12Hz tune, but given the size of the tubes I'm ordering (750mm), and the height of my ceiling, I can do 700L, and have enough room to make a port long enough to reach down to 10Hz.
In my simulation, I put a 1st order HP filter at 8Hz to simulate signal chain rolloff. I'm planning on actually measuring my signal chain to see where I truly stand, but at this point, I'm planning on running no HPF. At 50Hz, I aligned all three curves at 112db because I am building two of these, and as such I should gain a 3db advantage which will get me to 115db. Also, my room gain should start at 30Hz, so by the time I get to 20Hz, I should have at least a few db of room gain to boost 20Hz pretty close to 115db.
For power I'm planning an iNuke3000DSP. I like that it has a programmable peak limiter so that I can throw in some protection against >0dbFS peaks which are theoretically possible, from what I've read.
Is there something I'm not thinking about which might make me want to dial back to a 11 or 12Hz tune?
How about their DEQ as an alternative? From what I understand, I can set it up so that once power gets to a certain point (which in my case would be above reference), it will start filtering. Does your iNuke work this way, or is their DEQ limited to higher frequencies?AFAIK peak limiter is not a good way to protect drivers in vented boxes because they may unload with power well short of the limit. Both 15 and 12 Hz models I tried needed HPF.
Another important consideration is port velocity vs. port first resonance frequency. They say that for LLT with LPF no higher than 80Hz one should aim for at least 190Hz first res. freq. I personally opted for much higher number because my surrounds are crossed over higher and LFE channel can have content upto 120Hz. What numbers are you getting with your models?
DEQ would work if you could use it below 20Hz which is not an option.How about their DEQ as an alternative? From what I understand, I can set it up so that once power gets to a certain point (which in my case would be above reference), it will start filtering. Does your iNuke work this way, or is their DEQ limited to higher frequencies?
For my resonances, for 10, 11, and 12Hz it's giving me 146, 182, and 223Hz respectively. And my port velocities even without the low frequency rolloff is about 20m/s, which is below the chuffing limit according to "Flare-It" So it looks like 146 is perhaps a bit low for a first port resonance, and I should opt for an 11Hz tune.
I agree. But two 16 cu.ft boxes is the max I could fit behind my screen. Well I could have done 18 cu.ft. but the difference is insignificant. If I could do 26 cu.ft per driver - now that would be closer to optimum.To the OP, that FR tells me you need a larger enclosure.
Very well thought of sub. :T
In the movie I see the surround deforming. Are you driving the woofer over xmax?
Didn't the coil heat up too much? Looks like a long punishment for the coil.:gulp: