shizzzon

man, i run approx 7800w of power on a 250A alt and only 177aH in the rear with stock battery. How does my electrical system stay fine? Simple, you can't listen to it that loud for more than a few seconds, it's all for competition so i dont need to carry around boatloads of reserve. If u show off running at idle or just cant keep it revved at a comp, you need 300aH minimum suggested is my opinion.

ok, i have a question. Let's say i have a port that is oh... 20" long. Whatever port i make, it will protrude out of the box by 5" but the total port length for this example is 20" If i cut back 5" from the front of the port making only the port on the outside of the box flare, will the port length still be 20" long acoustically as if i never flared it or would it be 15" long + end correction? Basically, should i just start over with a whole new lengthy port and flare the outside and make the port as long as possible and then start cutting length off again and retest everything?

and u in texas.... why havent I got my stuff yet!!! i just ordered it 22 minutes ago Damnit! I'm gonna call them at midnight and see where my package is!

Ok, just ordered the "stuff". It will be shipping out tomorrow, factory only 3 hrs from my house so hopin i get it friday... crossin my fingers... If i get it by then, i'll have some test results by monday or earlier... If it comes monday, don't expect any results until middle to end of next week. I am gonna due another test tomorrow i think, if i got time, comparing the difference between using 1 port area vs another smaller port area and showing the difference of output of the two. I will be doing this off of low power output so possible port turbulence will not be an issue on the smaller port which would likely cause a problem with the test comparison if i were to blast it. This will show u guys the necessity of port area. This will also be posted in the SPL tricks section soon too.

Alright sounds good. Remember, the specs you gave earlier in this thread, i'm gonna use those as your external dimensions of the box. It is up to you to make sure that those dimensions are small enough to fit in your trunk once you build it. Since you need cargo space, i am assuming you will need the back half of the trunk free, correct? If this is true, your best bet is forward firing and sealing off the trunk. If you are willing to seal off the trunk... then welcome to SPL, If not, no biggie, but would be better if ya did.

ok, as soon u tell me what the best volume is for that BL AND pics of your trunk, i'll make you the graphic design.

if that amp is 1 ohm stable then u gotta get the Dual 2 version. If you plan to use that amp instead, i probably will suggest backing down to a BL. I would probably still keep same box design... I would contact Fi about it though and ask them what would be suggested as the best "bassrace NET volume for a single 15" BL" so i can get the specs to you for a design.

Yea, your best bet is to go with a single 15. I got a design for you but it's not gonna work with Fi, you gonna have to get a Sundown Nightshade Dual 1(since u gettin an amp rated at 3000w @0.5ohm). Box design - ~3.5 cubes NET (for the best in output) tuned to ~32hz with 62sqin of port area, very large port area! 15.5" high x 4" wide port. This is a rough draft of the design but i STRONGLY suggest you accept it for what you want to run with. I have heard the Nightshades in person from ALL kinds of setups! single 15 off of a saz-3000d = over 148s (tuned at 36hz) 2 18s and saz-3000d = just breaking 150db. there are 2 other setups i've heard but specs are unknown, just very loud, hehe. The nightshade can handle the power but recommended only for short several second runs. Do not drive around daily with it blastin with that much power as you will lose hearing and eventually damage sub. If you have experience with what to look for before damaging a sub and know how to setup amps properly then power is not a problem.

Well then you got it made then. Lower frequencies sound louder to the ear! If you gettin that mmats amp, then the BTL is the only sub that would survive, lol I'll look into your box dimensions later. Can you take some pics of your trunk from the outside and inside and post them here? If u got room for more than 1 sub, ill post it here but i gotta do some work then design u somethin.

so u are tellin us that you went through each of those subs with a 1500w amp and never broke 140db? You have major install and box design problems. It has nothing to do with your equipment, adding power is just a waste of your money now... I am willing to bet that I could break a 140 with 1500w in your trunk off of just 1 of those subs, any one of them tuned in the low 30s and over 143 with 2, yes i said more than 3db difference... Point is, it's not equipment, it's all install failure.

RMS in typical car audio language nowadays means to most people a constant output power. Well, you can't get constant output power with 90A of fusing with those numbers... At 85% efficiency of constant power at 2 ohms is only 1100w. Since.... the amp is rated real crazy off, all the guess work laid out here is gonna be just as crazy. So, best bet would be to assume the following- 4 ohm - 56V 14A 784w is what i'm expecting from this amp at 85% efficiency. 2 ohm- 68V 17A 1156w is what i'm expecting from this amp at 85% efficiency. remember, resistance rises and is different at each frequency so when the amp comes on to test... don't just assume because it's wired at 2 ohm (which is really anywhere between 1.2-1.8 ohms) that it's at 2 ohms.. because it isnt. That's why the ammeter completes the equation for finding actual resistance.

yes, it's good to know. Also, before even beginning to set the gain, i usually turn the head unit up 75% of the way. Whatever volume that the amp was tuned at, that volume level should ONLY be exceeded with caution because anything above the tuned volume should technically be nothing but clipping and distortion. I forgot to add that you can turn an amp's gain all the way up at a very low volume and it not clip but you should never turn an amp's gain all the over in the first place unless competing and burping for a couple seconds!

Gain = voltage matcher (bet nobody ever heard it called that, hehe) All preouts on the back of a head unit have a certain voltage that is uses. The gain control on an amp is used to MATCH that voltage. So, if your head unit outputs 4v, for example, that would be 4.0v flat which probably isn't perfect in the real world but if it was, then you'd turn the gain up until it matched to 4.0v. Not turned up high enough... just wastin potential, turn it up above what it is suppose to be, and you will start clipping the amp, overdriving it, etc... This is why gain controls are rated by volts and not numbers because it is NOT a volume control. Hell, there are some head units out there that output so high a voltage that if u buy a real cheap amp that can't accept the voltage high enough, it can damage the amp's inputs! Line driver's are a good example of this happening since they can output some serious voltage if not set properly. If you use a DMM, for best accuracy, it's also best to use an Ammeter to find actual resistance in real time so u can then properly set the gain via DMM in accordance to the real time resistance reading. Dmm measures voltage, Ammeter measures Amps Dmm probes go on + and - of amp's terminal. Ammeter CLAMPS around ONLY 1 of the 2 wires, positive or negative, not both! (or all the positives or all the negatives only) To get resistance, divide amps INTO voltage To get power output, multiply volts and amps together Once you have resistance, look up the approximate power output at that load. If it said 450w @4ohm rms, then you would do this match for example- 44v 10.5A Multiply those together to get 441w When divided, it equals 4 ohms, that's why i chose those numbers because it works with the example. So, now that we know that 44v is where it should be at at a real 4ohm load, if u were measuring in real time and got that resistance, 44v is what the DMM should be reading. That's how to bypass an o-scope.

well, i know that the box's response in an open air environment is different than the car's environment. I know my car's response down to the T but using that over what WinISD was saying was still throwing it off... So... i now use WinISD as an extra line in my add\remove programs, hehe.

Ok, this is giving me a headache... I dont know the exact volume of the box but it's somewhere between 12-13.5 cuft NET or it should be... This is what i've got and cant figure out why... I had a port 25.5" long that peaked at 50hz. I then had a port 22.25" long that peaked at 51hz I then had a port 20" long that peaked at 52hz I then had a port 18" long that peaked at 53hz I then had a port 16" long that peaked at 54hz The port extends through a double baffle (1.5" thick) and sticks out of the box 5" I always cut off the port length on the INSIDE of the box and retest. My peak frequency is 50hz. My LOUDEST port test was at length - 20" which peaks at 52hz but is loudest on the mic at 50hz... Anyways, explain this mind-boggling problem- I tried to use all this data to find actual internal volume of the box... So, as port length gets cut from the INSIDE, internal volume should increase... As internal volume increases, port tuning will peak closer to the tuning frequency as opposed to smaller boxes port tuning will peak alter on in the frequency range. So, why is it the shorter i make the port... the higher in tuning it is achieving? I know you are not suppose to use box building software but this is completely weird... According to calculations, i gain about 0.35 cuft every 2" i cut off the box or around there. I know from 25.5 to 16" i gain ~0.9cuft. So, if i gain 0.9 cuft by shrinkin port length 9", why is the port peaking at a higher note? On the mic, 50hz is still the loudest note using 16" length but on low volume 54hz is where it is peaking so that means the port is peaking at 54hz... According to graphs, when i gain internal volume, the port peak should drop BACK, NOT FORWARD! In my testing, it is acting like every time i cut some port length off, i dont gain anything but actually LOSE volume when i cut port length?!?! That is how i am having to graph it. ass-backwards.

well, it's gonna be a week or so since i gotta order it. I'm gonna get the $$$ Acoustastuff that partsexpress sells because people are sayin it's the best in it's genre so might as well try it rather than some bare minimum type. This is what i know so far- Using a certain port area which isn't large enough for the best in spl output- this port area + a given length = best metered output. shrink port length to change tuning but burp at same note = loss of spl. shrink port area to lower the tuning back to the above comparison, it's not the same spl level. Having the WRONG tuning but the proper port area will yield higher numbers vs having the right tuning but not enough port area.

if you actually read the reason for this thread, you'd see the whole point i am talking about polyfill for SPL is so I CAN lower tuning so i can get the port to peak at my car's frequency! My application is well worth a shot of using this technique. My port area is at it's largest right now. At 20" long, i metered the loudest possible. Cutting any more off will raise tuning. I am not done tuning my port yet, i want to cut more off but to get tuning to drop, i must add polyfill... I've read that using a short port, approximately 4-5" long at the most will yield the best SPL output IF it is peaking properly... I am trying to reach this length but tuning must drop as i get there. Also, I've been told this too- HOW DO YOU FLARE WOODEN PORTS?

yea that too. I knew of the Omega but i couldnt find what company made it.

u dont need larger alt, u would need about 300aH.

this is so the spider "breaks in" evenly. It's not like the sub is still drying or still curing... You break it in so as the spider loosens up, it loosens up evenly so you do not get uneven breakin, i dont know how else to word it. You will get the best output potential for a properly broken in spider. I've wanged on plenty of subs brand new as long as i limited excursion during the testing phases to see how loud some installs can go. I've never had a problem damaging a sub from excessive power. Now when excursion starts movin, i run it on low levels on the spider doesn't break in unevenly.

that wont happen? Actually you should be able to run more power when they are new due to stiffer spider... It's not suggested to pound like crazy on a brand new sub because it may not break the spider in evenly... not blow it.

also just got back from testing reducing port area to drop tuning... I tested dropping port area by sliding a single sheet of mdf in the port area one at a time... At low volume, all 3 sheets helped... at max volume, only 1 sheet was beneficial and not by much. I need to go back and test what is the port tuned to every time i shrunk it's area down again but i only gained 0.05dbs by shrinking area using a single sheet.... I gained WAY more than that with just an extra 2" on the port length, i believe it was 0.2dbs doin that before i cut it off.

so when u say amplify... there is no "except for..." scenario? it just amplifies pure and simple? If it's as easy as just sayin it... wouldnt just putting a pound of it in the port help SPL output considering i've got over a cube of airspace in the port alone.

oh no... it usually cost around $285 to repair... haha, i'm just messin with ya. A new regulator is around $100 so if it's already external, then it shouldnt be too much.

not really, i've got the largest enclosure with the largest port area i can fit... everything else is downhill.