posted
I am going to redesign my box. Its going to be very shallow (less than 5") but it will over the entire lenght of the back of my blazer with the seats down. The internal volume will be the same as my existing box with the only difference being that the subs are inverted. Will I notice a huge change in my SPL????????? since i am inverting all of my subs....do i have to reverse polarity on all of them??? Also it is going to be a ported box. I want the ports to fire up but my ports need to be over 9 inches long and my box is going to be only 5 inches deep. Is it ok to invert the port tubes also??? Meaning having the port tubes actually sticking out the top of the box. Please help me soon....i want to start building my box ASAP. Anyone who has experience inverting or has pics of inverted subs....please post pics so i can get some idea's about how to hide the wires going to the subs.
Posts: 247 | From: Louisiana | Registered: May 2001
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posted
no you shouldnt lose spl, most ppl gain a tad cause they lose the sub displacement=bigger sub enclosure = more spl in most cases,,,,,, so you should be fne, yes REVERSE the polarity =]. and also, you can have the port sticking out of the box,
just rmemeber to take into account the final port displacement...
posted
I've wanted to build an inverted sub box for a long time! I think the woofs look really cool that way... post pics when you're done!
-------------------- (1) PPI AMP PCX-2200 (800 Watts @4ohms Bridged) PCX-480 for my highs (2) DD 3512a's in a 4.4cube box with 50sq. inches of port tuned to 33Hz Street 1-2 [TEAM DD] 147.7dB My Sound Domain page Posts: 1655 | From: Tucson, AZ | Registered: Jul 2001
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posted
I don't believe you necessarley have to reverse the polairty. I know when I inverted my ID Spls I left it the same, but dropped a db........ if I was out of phase at 145.6 db's just imagine what I would have been in phase?!?!?!
-------------------- The Peoples Mod/Champ
2006 Bass Race World Finals 130-139.9 Champion Using Crunch Sub Woofers! 2007 Bass Race Indy Regionals 130-139.9 3rd Place
If you ain't down with the Iggster and his sounds, I got 2 words for ya: Bass Race Posts: 28461 | From: Tinley Park, Illinoize | Registered: Jul 1999
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quote:Originally posted by Audiophyle: Absolute polarity is of little concern...
Relative polarity however, is the most important thing....
correct.....if both are wired wrong it is no big deal. If one is correct and the other is wrong the diff is night and day. On the subject of will you gain or lose....flip a coin. I see people gain more often with ported than I do sealed boxes. The reason for this may be that you have more cone in the box instead of in the air. I dont know. try it and test it.
-------------------- "The Phil" Team Excel audio Excel Audio, PHILESTER, DB+, DDMMats, Kamiraa, Iggster, Bangin Z, Homie, Iceman91, Jimmyo007, BumpinBobby, TrevorGolf, Team Excel Audio s 1-2, MyEarzHurt, and a whole f**k load more. (hope I didnt forget anyone:)) -1 99' Nissan Sentra -2 modified ARC 2500CXLs -3 modified AT Extreams -1 12 ft^3 half wall with 250 inch^2 of port. Philip_J_Lester@yahoo.com
Posts: 2654 | From: unknown bowels of the underworld | Registered: Aug 2000
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posted
I'm not trying to get a fire started here, but why is it that if you gain SPL from inverting, that you don't see many people at shows doing it? I understand the sub displacement thing completely though.
Posts: 367 | Registered: Jun 2001
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posted
With my Alpine 7873, and I believe the higher models do it as well, there is a feature by, at the tough of a button that allows you to switch the signal for inverted subs.........
Posts: 5534 | From: CO | Registered: Apr 2001
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posted
Actually, I'd expect a loss in SPL in most cases ( very small, but a loss none the less). Reason being that you would have a little less surface area. The area that was a dustcap is now a useless VC, with no radiating surface. Now air will move through a vented pole, but in most cases the pole vent is so small that it would resist air flow to the point of making it useless ( vented poles are for cooling, not displacement). Plus, with alot of these drivers with HUGE frames and magnets the air movement might be restricted a little. This is assuming the actual volume is the same, if you just invert them in the same vented cabinet, the tuning will be a little higher ( larger box same port), and would probably offset the change.
Now, for a SPL competitor, this might make a difference, but for the average Joe, I doubt you'd ever notice the difference (VERY small at worst ).
[ 08-25-2001: Message edited by: I'm Yopu ] man I can't spell!
[ 08-25-2001: Message edited by: I'm Yopu ]
-------------------- I Am Yopu, and no matter what you say, you can't convince me otherwise!!!!
quote:Originally posted by Pounding-the-chubb: I'm not trying to get a fire started here, but why is it that if you gain SPL from inverting, that you don't see many people at shows doing it? I understand the sub displacement thing completely though.
If you've got a wall, inverted subs would often violate the string rule.
-------------------- My old work in progress. Kickpanel instructions.
posted
my friend actually gained spl by inverting his subs. not alot but still a noticeable audible gain
-------------------- 98 Honda CR-V EX pioneer 9300 2 15w3s JBL BP1200.1 JBL P180.2 Kicker K60 Optima red top FINALLY IN!!! but too damn lazy to clean up the install Posts: 4312 | From: NEWARK NJ | Registered: Jan 2001
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posted
If all the subs are inverted then you don't reverse the polarity.
-------------------- Team Street Sounds 2002 M4 and MR4 TN Record Holder 2001 MR6 World Record and M6 TN Record Posts: 537 | From: carthage,tn | Registered: Feb 2001
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posted
It is possible you will gain spl due to the increased airspace in the box itself... if you take the displacement that you would normally account for the magnet and motor structure and add that to the internal box space, you change alot of parameters of the box.
On the issue of reversing polarity - as stated before, you dont need to if it is a db drag car - assumedly all you have in the car is subs... and as long as they are all in phase with each other then it matters little if it is wired one way or the other off of the amps terminals. However... if you have mid-highs in your car, you will want to reverse the polarity to maintain the overall polarity of all the speaker cones in your car. Just like having one sub out of phase with another - if you have your subs out of phase with your midbass- midrange drivers, you can lose a little performance in the midbass range, so try to keep them all phased properly.
On the issue with the sub not moving as much air (ported boxes), you have to remember that there are 2 waves from a sub, one from the front, one from the back... so even IF a subs motor structure degraded the amount of air coming off the front of the woofer, the air coming off the back of the woofer will be increased in relation to before, making the net change zero.
You may notice a change due to the velocity of air coming out of the port however, seeings as how you may have higher pressure in the box - but again, the added pressure in the box from having more cone area firing into the box, my be offset by the amount of additional airspace the sub needs to compress due to the loss of the motor structure in the box.
posted
Stupid question I know, but I figure since i'm going to be majoring in electrical engineering next year I should know: How do you "reverse the polarity" of your subs? Switch the + wires to -? or something...
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