Help me build this box..Plans
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Silver Member Username: JohnfiacIL USA Post Number: 602 Registered: Mar-06 | I just changed my work schedule and now fginnaly have plenty of free time to goof around with things. I want to build a SPL box for these 2 mofo subs... I am going with wood that is better then mdf.. i hate that stuff.. its like birch i think really hard wood. What should i tune it to and how big for each sub chamber... does any1 have a diagram for me to do this? i want one big port hole goin up and down in the center of the subs... or if sum1 can be nice and make me a diagram... Power Acoustik Mofo 12's with my amp doing about 65V ac 65x65 = 2112 rms at 2ohm.. i dont care if my subs end up getting cliped or what not.. i jsut want to put these subs to the test to see how much louder they can actually get, i will prolly give them less power if they are in a real custom box made specifacally for them so i dont bottom them out or anything but how they are now i have tested my outputs on the jbl bp1200.1 mono and thats my math from it and it still sounds great and hits hard.. did i do the math wrong or am i just setting the gain a bit to high? because on the amp it has writing on where 4v -2.5mV is and its about on that spot and the multi meter gave me the 65VAC with the subs wired at 2ohm.. but it puts the amp into protect at 1ohm but it still sounds good like not distorted and all...BTW when setting a gain like that, tweaking gain with multi meter hooked to amp outputs with test tone and all.... if its a underrated amp do you higher it like that? |
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Silver Member Username: Bass__monkeyLas Vegas, Nevada U.S. of A. Post Number: 137 Registered: Sep-06 | what vehicle? give me dimensions to work with... (hopefully with all my design notes and projects i'll have one for u.) |
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Silver Member Username: JohnfiacIL USA Post Number: 603 Registered: Mar-06 | its a 99 blazer LT im not sure on dimensions yet, but i will have those tomorrow, i am to drunk to even try measuring it i dont want to fu<k it up, btw it took me like 20 minutes to type this so you should see why i wouldnt trust my measure ments |
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Silver Member Username: JohnfiacIL USA Post Number: 604 Registered: Mar-06 | Ok, here are the only specs you need to know, anthing else you can maek to what you think will sound better (i have absoulutly no box box building skills, never done it before) The box can not be any longer then 37" so that it can still fit in between the wheel well you can make it deeper tho, (back of backseats to rear door\hatch) and maybe about 16" tall, any of those except the 37" long can be changed. The specs PA supplyed are below. I want it to get as LOUD as Possible while still getting low, i believe my current setup is either 46\56hz im not sure, and its 1.25cu each sub. There should eaisily e a noticable dfference in sound once i put them in a different box right? Maybe my JBL1200.1 will let me run them at 1ohm then? t goes into protect really quick once i start adding power.. not sure if its just cuz they are cheap subs or what..oor if this amp truly doesnt support 1ohm like stated... but id guess the sub(s) if anything.. lol (2) 2400 watts power handling 1200 Watts RMS 270 oz . magnet 3± BASV/Kapton Hybrid 18 AWG Voice Coil SPL 90 dB Fs: 36.7 Hz Vas: 0.73 cu.ft. Qms: 5.34 ? Qes: 0.36 ? Qts: 0.3363 Xmax: 0.7" Sealed box: N/A Ported box: 2.4 cu..Ft. Tuning: 40 Hz Port size: 3± (dia)x 6.75± (length) # of ports: 2 Mounting Depth: 6.75± |
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Silver Member Username: J_baby15Kentucky Post Number: 613 Registered: Feb-06 | 46/56hz is really high tuning lol. |
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Silver Member Username: JohnfiacIL USA Post Number: 605 Registered: Mar-06 | those were pre-fab boxes i bought from best buy.... my first 12" boxes ever.. dont laugh at me, im sure every single one of u bought a pre-fab box as your first lol (these are 1year old btw) |
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Gold Member Username: FrkkevinLake Worth, Texas US Post Number: 1104 Registered: Nov-05 | I can honeslty say I've never bought a pre-fab box.. ever since my first system I build a nice sealed enclosure that fit snug agaisnt my trunk to leave it clean.. I'd build the box 5^3 before displacment and use 4 4" aero ports tuned to 45hz to start.. using aeros will allow you to retune quickly to get the most of your setup until you find the frequency your blazer likes.. I'd fire the subs up and ports back... |
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Silver Member Username: JohnfiacIL USA Post Number: 606 Registered: Mar-06 | i was sorta thinking of firing the subs up and port toward the back to, but i just want it LOUD but i dont wanna keep blowing money for ports.. i want it wood and all setup when the box is built |
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Silver Member Username: JohnfiacIL USA Post Number: 607 Registered: Mar-06 | Didnt..... ^bump |
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Silver Member Username: JohnfiacIL USA Post Number: 610 Registered: Mar-06 | ^^BUMP!!!!! COMON PEOPLE STOP SLACKING!!! lol |
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Gold Member Username: FrkkevinLake Worth, Texas US Post Number: 1139 Registered: Nov-05 | if you want it loud and don't really plan on competing i'd tune to 35hz with a slot port .. still subs firing up and port back. but if you want to compete a port that you can change is very recommended.. |
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Silver Member Username: JohnfiacIL USA Post Number: 613 Registered: Mar-06 | I just want it loud and to see the difference in sound from pre-fab boxes and custom boxes. These are only power acoustik subs, if i tryed to compete i would probally get laughed bad... Does anyone have plans i could use for this? I was thinkink somwhere around the area of.... 38inch wide 16inch tall 24inch depth 1inch thick wood leaves me with 6.41667 CU before displacment, each sub is .73 cu ft. Vas that should leave me around 2.4~cu after displacment. How would i go about tuning... how wide\deep does the port have to be, i would prefer a slot port rather then a round port. If you need to modify this in anyway to do so, i dont mind.. but let me know how you went about doing it, i want to get use to building custom boxes for different subs. Subs firing Up, ports firing the rear..  |
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Silver Member Username: JohnfiacIL USA Post Number: 614 Registered: Mar-06 | BTW the 6.41667 CU is before dividing the box into the 2 different sections, i am still wondering on how to do the port before i worry about that. |
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Gold Member Username: SouthernrebelMonroe, Louisiana USA Post Number: 3475 Registered: Mar-04 | killa, there is no way to wire 2 dual 2ohm mofo's to 1ohm...only 2ohm or .5ohm. If you are wireing them to that bp1200.1 in parrallel...that is .5ohm and thats why its shutting off. also, there is no chance that bp1200.1 is giving you 2000w+. your math is alil off. V^2=power is the wrong formula to find power in a reactive load. V x A = power is the correct way. you are clipping the hell out of that amp at 65vac... unhook the subs and put your DMM on the outputs of the amps...run a 60hz tone to the amp and tune the gain up till you get 49vac. then wire those mofo's in series-parrallel and give that bp1200.1 a 2ohm nominal load. as for a box...try ~5cuft net tuned to 42hz to start off, that blazer is prolly going to want to peak around 48hz. 36"x15x24" w/ 1" plywood would work. and like kevin said, try 4 external 4" flared ports. Have the subs firing up and ports firing back. Ports 13.5" long. Vas is not your sub displacment...its a parameter that discribes the subs suspension. those subs displacment is around .18cuft if i remember correctly. |
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Silver Member Username: JohnfiacIL USA Post Number: 623 Registered: Mar-06 | ok when i ran them at 1ohm i was not running them togethor, i was running one at a time to make sure i like how it acts at the 1 ohm. I found out why it was not working and was clipping (HU EQ was set to high, and it works fine on 1 sub now) Also... how exactly do i tell if i am clipping my amp.. if its underrated why set it for the 49.6 VAC like i was told to... would i do it up a lil more then that... also i was told to set it with a 50hz test tone. I lowered the amps gain since but during this whole time once again THE AMP DIDNT EVEN BREAK A SWEAT AFTER HOURS OF BEING OVERCLOCKED (gain to high) can anybody draw me some sort of plans for the box? i can get the cu set correctly.. im just not good with the tuning process.. BTW marshall the way i was calculating the math was 65x65=4225\2 = 2112 yes i prolly was clipping the amp but it took it like a champ.. and my power gauge barely moved at all even at idle.. also is the myth about tweeters..mids annd highs and all... if you are clipping they are the first to make a sound difference? like they get quieter.. i heard that somwhere... my tweeters\mids never ever change volume. |
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Gold Member Username: SouthernrebelMonroe, Louisiana USA Post Number: 3502 Registered: Mar-04 | The reason i say use a 60hz tone is because that is where most DMM's are most accurate. The reason i say your math is off is because you cant actually get an amp's output w/ only a DMM. You need to know both voltage and current. Even though your amp is wired to get 2ohm DCR, it doesnt actually see 2ohm. That is because of box rise...your AC impedence will be different at EVERY freqency. Thus, amps put out different amounts of power at different freqs. It all depends on the inductance of the sub(s). Since speakers present an amp w/ a reactive (inductive) load and impedance changes....(V^2)/ohm(nominal) doesnt work correctly. EX...2ohm dcr. at a given freq, you may see 50Vac but actually get 20amps of current. 50v x 15a = 750 at that freq, your box rise would be: 50v / 15a = 3.33ohm Yes, it is easier to hear clipping in tweets/mids than w/ subs because your ears are more sensitive in the freq range tweets/mids produce. You can hear clipping in subs, but you have to listen close to catch the amp right where it starts to clip. W/ that amp producing 65v, its well into clipping. The outputs on your HU can clip too if the EQ/Loudness feature is set too high. Also, if you are using bass boost on the amp...turn it back to 0dB. Bass boost is a sure way to kill a sub/amp if you are clipping it...it causes worse clipping at certain freqs. |
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Silver Member Username: JohnfiacIL USA Post Number: 631 Registered: Mar-06 | i have a 600$ fluke... im sure its accurate.. atleast it better be!!! well with this all said CAN SOMEBODY PLEASE MAKE ME A FU<King Design??????? for the tuning..... COMON PEOPLE!!!!!!!!!!! |
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Silver Member Username: JohnfiacIL USA Post Number: 632 Registered: Mar-06 | ^bump |
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Silver Member Username: JohnfiacIL USA Post Number: 633 Registered: Mar-06 | ^bump ^bump ....i would like to get this done this weekend before it starts getting way to cold outside to do this and make me wait a year.... |
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Gold Member Username: SouthernrebelMonroe, Louisiana USA Post Number: 3510 Registered: Mar-04 | the box you have designed will work pretty well. 35"x16"x24" w/ 3/4" MDF. that will be 6.32cuft gross. try out interchangable ports, that way you can unbolt them and change them when you test-n-tune. If i remember correctly, blazers like ~48-50hz. Try tuning to 40-42hz to start off. Subs up port back. here is my interchangable port how to: http://www.cardomain.com/ride/650399/6 start off w/ a port w/ a 5.5"x12" opening, 16" long. That will give you 4.8cuft net tuned to 40hz. or one w/ a 6"x12" opening, 13" long...that will give you 5cuft net tuned to 44hz. round off the port. |
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Gold Member Username: FrkkevinLake Worth, Texas US Post Number: 1195 Registered: Nov-05 | round off the port edges*  .. either that or invest in some aeros.. easy to retune but it is the more expensive way |
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Silver Member Username: JohnfiacIL USA Post Number: 636 Registered: Mar-06 | as for 16" long do you mean the piece's of wood i will be using to seperate the subs and put that in the middle of the port coming from the part of the box against the seats facing the rear toward the port?.. ill draw a lil picture... |
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Silver Member Username: JohnfiacIL USA Post Number: 637 Registered: Mar-06 |  |
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Silver Member Username: JohnfiacIL USA Post Number: 640 Registered: Mar-06 | ^bump anyone..... i have most of the box done already.. i need the alst bit of info on the port..... i dont wanna F it up i spent about 100$ on wood :p i got the good stuff oak |
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Silver Member Username: JohnfiacIL USA Post Number: 641 Registered: Mar-06 | BUMP^!!!!!! |
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Gold Member Username: FrkkevinLake Worth, Texas US Post Number: 1211 Registered: Nov-05 | marshall meant for the port dimensions 12(h)x5.5(w)x16(l) soo.. 2) 5.5x16 2) 13.5x16 the opening needs to be the dimensions he gave you.. if your mounting the port to the inside of the box make the length 15.25inches long.. if its going to be flush with the box 16 |
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Silver Member Username: JohnfiacIL USA Post Number: 644 Registered: Mar-06 | the box is drying..... only need to cut out the top piece that hold the subs and one side of the box.... :D the length is 15.25 at 12x5.5 with about 2.5-2.75 cu |
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Silver Member Username: JohnfiacIL USA Post Number: 645 Registered: Mar-06 | and its tuned to 40 like the manual even says.. well it say 40hz freq response.... this box should still be good for other subs when i get rid of these garbage things right? or mayb i can get lucky and have the first setup with PA that sound nice....i can blow my windows out....hahah jp... what about that thread..sony exploiuts ROFL what a lame  |
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Silver Member Username: JohnfiacIL USA Post Number: 650 Registered: Mar-06 | caulk\silicone would be good to seal the box with right? i Have wood glue in between all the pieces of wood that were glued togethor so the screws basically tightened and squeezed out the glue, i just want a double air tight seal |
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