ok guys...i jumped from 145.1 to 146.6 today w/ my new box for my SX. I have time tonite to change stuff around a lil and try to up my score a lil more...i wanna try and top 147 if possible.
i'm #1 in my class right now, but i'm #3 over all in the entire competition. the top three over all are: 1st 148.2 (w/ 2 selenium 15's in a rex, ~1000w each) 2nd 146.7 (w/ 2 pioneer premier 12's in a jeep grand cherekee, 800wrms+ each) 3rd 146.6 (me, 1 sx15 w/ a bp1200.1)
what do you guys think i should do: 1) add an extra layer of deadening to my passenger side door (the side they meter on)
2) put a layer of deadenin in my drivers side door (i dont have any deadening there yet)
i just duct-taped around the outside of the sub (to make the sub-baffle seal 100% air tight). duct-taped inside the box around the 1/2" threaded rod i have for a brace (where it goes through the box). also added alil sound deadening in the passenger side door. I couldnt get the tape to do right in the corners, so i didnt even bother. I'll prolly resin the box later on.
w/ an all out burp, my voltage is only dropping to 12.9-13V. I'm going to reposition the seats when i burp tomorrow (passenger seat layed all the way back...drivers seat leaned all the way foreward)
i cant help but think that i'm overlooking something that might help me....hummm.
I seem to remember you talking about your box flexing in the past if there still is any make improvements to make the box sturdier also sometimes adding deading can make you loose spl .....bingo!!! got one for ya that comes to mind make what i call a horn port I have yet to try this idea but heres how i came up with it.....say a word at normal tone from your mouth...now..say the same word at the same tone but this time put your hands around your mouth (like when you yell to someone far away) and say the word over but each time varing your hands width around your mouth and youll see what i did (it got louder) when you reached a certain angle...another thing i noticed was that the air i excerted saying the word got projected further and made a piece of paper i had on my desk at mouth level move (something it didnt do till the right position was met around my mouth) I tested this theory using my handheld meter in a fixed postion and it seemed to at least make a 1 db increase (assuming I was saying the word at the same tone each time...I also know when i did this test at different physical locations the results sometimes by ear seemed to be even better.....basically what i mean by a port horn is a addon added to the end of your port with almost like a v type flare if you do testing youll no when youve hit the right postion i think...build the addon so it can be adjusted on the fly that way you dont have to make multiple port horns....let me know how this works if you try it
another idea i think i read about a guy nicknamed db don talk about doing is rounding off the corners of your subwoofer enclosure (internally) aparently this helps increase spl ...all you would have to do is make up for lost space and again you could make a temporary insert to try this idea out
another idea occured to me you said you had box rise if you have the excursion left you could probably get that down but it would require a new box and what i think that would mean is a different kind of dual chambered box (and no its not an abc box) its a theory i have
any loss in acoustical energy is going to kill your maximum SPL available. Its conservation of energy. Your system can put out a certain amount of energy. If you lose that energy through box flex and such than your numbers are gunna suffer. I would say look to your enclosure for a solution. Build a box around your existing box, meaning glue/screw 3/4" MDF around all sides of the box. This will minimize box flex and could possibly help you achieve your goal.
ok I wanted to take time to explain my dual chambered idea now you said your just burping here so my theory is a little easier to test so here goes. The other day I was thinking about aperiodic boxes and liked the idea how you can "tune them" by ear using a fiberglass insulation "the kind used for housing" anyway from what I remember this effect also has an effect on impedance rise as well so if im right you can make it low enough impedance wise at the frequency you want to burp at. I know I know but how can I use that for spl? Well I figured if you build a vent like a vario vent a 4 inch or larger drain plug with open cell foam inserted in the rear center of the first main enclosure and add a second chamber probably much larger than your first enclosure then the air escaping out of the first enclosure is contained and helping to maintain pressure. This idea is used by another company by the way in their idea you go 1/3 first chamber 2/3 2nd chamber but theres is used for sq with a nice midbass effect achieved but i figured why not use it for spl puposes since a vario vent can reduce box rise from what ive read. (you could even make a variovent actually like an aperiodic design with wire mesh and add thickness with fiberglass and test with tones and a meter to see how it effects box rise after all were not after a musical box just a one note wonder