desinging new box

[darcmater]

Well I have decided to build a new box for my subs and rearrange how the amps sit. So first thing I did was go out and get some ruff measurements of the cargo area and my old box. After doing some calculations I realized the place I had do the intsall messed up slightly and the box is set to about 1.55 cuft which is the proper size for a ported box instead of the 0.95 cuft needed for my sealed box. So Now I am a undecided on if I want to make my new box sealed or ported. Originally I had wanted to do a ported since my subs never did seem to hit as hard as I had wanted, and figured making a ported one would solve that problem. After sublime mentioned how the subs were not hitting as hard as 3x 12's should I messed around and changed the sub setting on my headunit from 2 to 6(the max setting) and it deffinately made a noticeable improvement. I can't turn the volume past 27 or so, out of 40, with out it being just to much.So i am wondering is a properly sized sealed box would take care of my needs and allow me to turn the sub control on the head unit back down to 2 or so, I really don't like maxing them like that. Or if I should go ahead and make a new ported box or possibly modding my current one by adding ports to it. I like listening to most types of music and have allways been told a sealed box does best since a ported is usually set to a particular frequency. Now I won't lie and say I don't like lots of bass, and generally listen to mostly rap and metal type music. But I like haveing a well rounded system, whether i use it that way or not.As for a bit of background info my subs are 6ohm dvc, 350rms watts, and the amp i am useing is a jbl GTO 1201.1 that is stable down to 2ohm. So the best set up I know is a series/parallel at 4ohm load. The amp is rated at 787w rms at 4ohm. So the subs are getting 261watts if i did my math right.One last thing I had been doing some research on differant terms I see mentioned on the spec sheats I have and thanks to the nice links sublime had given me have been lookign into what they mean. However even if I find out what they stand for, I really don't undertsand what they really mean. Such as QTS and QES. I think XMX represented in mm represents how far the cone can move past its resting point safely. Also the spec sheet mentions my subs have 28 FS(hz) and am not sure what that means. Also the another sheet I have for my subs gives a D and L for the port, and then next to it says Fb Hz of 40. Does that mean thats the dimensions to set the frequency of the port to 40 or that 40 is the recomend setting for optimal use of the subs?Lots of questions and number I know, but thanks ina dvance for any info you can contribute

[Sublimewind]

So, you have the specs for the subs then.... good... Have a look over here for all of your needed explainations... http://www.the12volt.com/caraudio/thiele.aspStarting from the back and working forward... The Fb of your port is the Enclosure resonance of a ported box, the box resonanace or the tuning frequence is where it's going to make the "most" bass... The D and L are Diameter and Leingth of the port required to get the 40hz Fb.. Fs is the "free air" resonance of the driver sans box... Your XMX should really be Xmax, but you are correct in saying that it is the linear excursion limit of the driver... The "Q" factors you are just going to have to read about...lol... to much to explaine ATM... With 3 6ohm DVC drivers, they would typically get individually wired in series, so each would represent a 12ohm load, then all 3 drivers would get wired together in PARELLEL to show the amp a total of a 3ohm load... This was BIG back in the mid/late 90's.... and still works today... When you made your mesurements, did you subtract 1.5" from each (L/W/H) to get inside dimentions? if not you need to re-run your calcs... as far as the bass goes, sealed can to a GREAT job... You remember me mentioning those Directed 10's I had... Put 2 of them in my GF's brothers car with my Directed 600d (about 750w @1ohm) and it POUNDS.... Blew the kicker 15" he had running, right out of the water...!!!The box is the most important thing in a sub system, it makes or breaks a sub, it provides the woofer control, and sometimes the manufacture given specs for box size don't really to the woofer justice.... Search out the "free" program winISD, it is a box designing program, it's somewhat easy to use, and plug in the parameters you have, it might take some reading of tutorials to figure it out completely, but you can do it... all in all, if your box was designed for a ported design, and it is to big, your subs would lack a LOT of control, smaller box = tighter, bigger box = looser...Hope this helps man...

[darcmater]

thanks sublime, have a clarification question for you in regards to the wiring portion did u mean somethign like this?I am thinking not since they state that gives a 4 0hm load and you mentioned 3 ohm load, which would be better since I would get a bit more power out of the amp that way. Related to that is there a formula to calculate the watts an amp would put out if you know the stats at 4 ohm and at 2 ohm? I am thinking it is probably a logrithmic equationoh and yes i minused the thickness of the wood to get the accurate interior dimensions of the box : )

[Sublimewind]

Hmm, well maybe my math was off slightly with the ohm load, but the difference between 4 ohm and 3 ohm is nominal... The funny thing about it all is that impedance changes with frequency, that is WHY the ohm values are stated in "nominal" values.. It's easily tested if you have a miltimeter, you can set it to resistance (ohms) and connect it to the terminals of ANY speaker and lightly push on the cone of the speaker and you get and instant change.. lol.. that looks to be correct though... As far as doubling and halving of the output power with respect to impedance, it's "almost" logrithmic, but it really depends on the amp... you have good amps, really good amps, heck Alba Gates set world records with those amps...!!! (GIS Alba Gates SPL or SQ, it's cool)Ok, so your box IS really to big then... hmmm it sure didn't sound like it...??? I would have expected it to sound all flabby, but it didn't really... It would be interesting to see what those subs would do in a proper spec box...!!! You know Kove has been out of business for a few years at least now, don't you? I'm not saying that is a bad thing what-so-ever, just thought I would pass on the info... as long as you have a spec sheet for them, you're good to go... I'm trying to come up with a box design in my head that would get you some of your trunk back to... I'm thinking rear firing, like they are now, but a smaller box of course, and maybe mount the amps to the front of it, right behind the seat, at least that way you would have "some" usable trunk.. and the amps would be hidden a "little" better...

[darcmater]

well i got off work early tonight around 2am and have been playign with the winisd program since then trying differant number, subs, everything just to see what all the numbers mean. Reading there help section and beeing able to look at the graphs has greatly helped me increase my understanding a lot i think. I think/hope the reason the shop made my box bigger was because of this(stolen from their help section, " A larger suspension (bigger box) will allow the woofer to move more freely, thereby yielding a lower bass response, but at a price in power handling, of course" Considering the sub is only getting like 260 watts and is listed at 350rms. Plus according to the numbers/graphs the subs dont reproduce frequencies well below 57 in a sealed box at the -3db,which is apparently when a sub stops pruduceing frequencies well. How "not" well wasn't clearly defined. I tried playing with differant subs/boxes to tell if that was bad/good for my subs. In a ported box at the suggested volume the frequency cut off was at 40 which I assume is better but I am really not sure what most music ranges in that a sub is best suited/designed for, in particular for rap/metel sicne that is what I mostly listen to.If I had it to do over again I would not get the kove subs, they are nice, but being 6ohm just makes wireing them a mess, especially with an amp that is not stable at 1 ohm and from what i could gleam from the program do not go as low as other well know brands. Oh yeah I know they are out of business, although its rumored they got bought out by somebody and they did win many competitions while they were in business but with their armegedan series I do believe. Never been a fan of kicker, they always seemed the preppy/trendy brand to, perhaps some nice mtx's I haven't had any of those in a while : )

[Sublimewind]

Well, let me know if you are in the market for subs and what you are looking for, I can always help there.... There are a LOT of compainies that do better than the "mainstream" these days... I donno if I mentioned this or not, but the Subie is now getting a pair if 15's..!!! Image Dynamics IDQ15's to be exact.. I'll be running them "boxless" or in Infinite Baffle.... It's gonna be killer... Not much to look at, but they are one of the most highly regarded sound quality subs to date... How about some old school goodness I just picked up, SoundStream Ref705s It's 75x4 and 300x1...!!! My Rockford Fosgate Power 1000 5ch Limited Edition (2072 of 2500) might be going on the chopping block, I haven't decided yet, but, if interested it's 1ohm stable on all channels... The birth sheet that it comes with shows as tested output of 111x4@4ohm and 698x1@2ohm(941@1ohm.!!!)... Just to keep things interesting...lol...

[darcmater]

just to toss it out there, i made a nice paint version of my current box incase you wanted to double check my numbers and make sure it really is to big. The numbers in the picture are in inches and of the outermost dimensions . I got 1827 in^3 for the main box per chamber and 543 for the little triangle portian per chamber so add up to a total of 2370, which if I did my other math right should be 1640 in^3 according to my sheet, 0.95ft^3 should be 1640 in^3 I believe : ) Think that menas the box is like 60% or so to big.As for a design I know it won't be flashy by any means but I could cut the front of the box off to reduce the volume to the right size. But half the fun of this is comeign up with a new and improved version : )dang internets fault i tell yah

[Sublimewind]

Quote, originally posted by darcmater »just to toss it out there, i made a nice paint version of my current box incase you wanted to double check my numbers and make sure it really is to big. The numbers in the picture are in inches and of the outermost dimensions . I got 1827 in^3 for the main box per chamber and 543 for the little triangle portian per chamber so add up to a total of 2370, which if I did my other math right should be 1640 in^3 according to my sheet, 0.95ft^3 should be 1640 in^3 I believe : ) Think that menas the box is like 60% or so to big.As for a design I know it won't be flashy by any means but I could cut the front of the box off to reduce the volume to the right size. But half the fun of this is comeign up with a new and improved version : )Me thinks you forgot to post the pic...

[darcmater]

here is a new idea I been working onI would probably mount the amps on the back side of the box betweeen it and the rear seat. The grey box section on the back wall would have some sort of additional wood there to remove the extra air space. The interior height would be 13inches for a total of 14.5 inches tall. I have no idea how I would carpet somethign like this though, I more use to regular square/rectangular boxes

[darcmater]

Oh I forgot to post this pic I saw of a cool design, just not sure where I would put the 3rd sub at : )

[Sublimewind]

Thanks, that pics been around for YEARS though.... I would bother using the 3rd sub if I had THAT "box"...lol

[darcmater]

this is probably ghetto, but is possible/do peopel ever use stuff like fiberglass bondo or even regular bondo on boxes so they can paint them? If it is possible I assume a thick enough layer will have to be used so no crackign apoears at any visablw joints.

[Sublimewind]

Quote, originally posted by darcmater »this is probably ghetto, but is possible/do peopel ever use stuff like fiberglass bondo or even regular bondo on boxes so they can paint them? If it is possible I assume a thick enough layer will have to be used so no crackign apoears at any visablw joints.Yep, they do... They typically start with "kitty hair" or fiberglass bondo, get it into the closest basic shape they want, after doing a lot of sanding, and then they start in with the regular bondo and smooth it... it's a LOT of sanding... a LOT... power tools and "rasps" are your friend for this.. sorry i'm not much help on the box, to be perfectly honest, i haven't built many myself... I've seen a lot build, read a lot, but haven't actually constructed many (of my own, I used to work for a company that made pre-fab boxes, so i've built HUNDREDS, none but a few were my own custom boxes)

[darcmater]

well I think I have the final design down, but one last question. How do you think having the subs firing up instead of towards the back would change the dynamics of the sound in the car? Also what about is I don't do individual sealed chambers for the 3 subs, and they are not all facing the same way? Like if one sub was ontop firing up and the other 2 are on the side, one on each side, firing?

[Sublimewind]

Quote, originally posted by darcmater »well I think I have the final design down, but one last question. How do you think having the subs firing up instead of towards the back would change the dynamics of the sound in the car? Also what about is I don't do individual sealed chambers for the 3 subs, and they are not all facing the same way? Like if one sub was ontop firing up and the other 2 are on the side, one on each side, firing?Changing the direction of the subs WILL change the sound... how much is hard to say... Having one up and the other another direction will only make it worse, but again, how much or how BETTER it could be is hard to say without trying it out...