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ncc74656

SP4 box for back seat. am i designing this right?

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i just ordered my SP4 18 today, i thought i had a box idea but i was told it was not very good so i need some help.

 

back seat of a dodge ram 2500, i have 30HX36WX31D max space, smaller is better but thats what i have to work with. i intend to mount it on a new tool box im installing in place of the rear seat. if i use 2 .75" MDF sheets to make 1.5" panels and build the entire box of that do i need to double up on baffle? do i need bracing? i currently have a ZX2500.1 to power it (do you think i should upgrade?).

 

i am not sure exactly where to tune it so i planned on starting with a high tune and an extra thick bottom and then extending the port and pulling parts of hte extra bottom panel out to keep the cubic footage the same while tuning. sweeping from 32-34hz is what i was going to try. what are your thoughts?

 

here is a picture and tores of what i think i should have for optimal. i listen to lots of techno, rock, trance, kinda all over the board and i want to be able to kill the lows while still destroying hte highs. i seriously do not want any dead spots. im upgrading from a BL 18 that was just not loud enough.

 

what should i change? thanks.

 

http://imgur.com/a/rl7BU#1

 

5Adk0Rdl.png

 

0lulbf0.jpg

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If no one has helped you by tomorrow after noon ill take a look at everything and help ya out.

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thank you, the last BL that i bought i paid a guy (who came very highly recommended i might add) a lot of money to build a box and i feel like i did not get what i wanted out of the sub. this time round i really want to get a firm grasp on all the concepts of box building and do it myself so i know what im getting.   to his defense he did say he had never built a box for an 18 before and after delivering mine he said he never would again.

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Ill check you dimensions in a minute but first doubling all around wouldn't be nessessary unless you're competing and need every tenth of a DB. I would do single everywhere and double up on baffle. Then Bracing where it needs it. The zx2500 will be plenty for that sub. The lowest you can run the kicker amp is 2 ohms right? Did you order a dual 1 ohm?

In your 3rd paragraph, I don't really follow you lol you don't need to make it more difficult than it is. Go in Torres and keep messing around till something works. Just make sure the port length doesn't go to far into the side wall. What do you mean by low? (Give me the hz or a song?) what do you mean by highs(hz or song?). People have completely different ideas of lows and highs. But with the music you said you listen to you should be fine with tuning around 33hz.

Ohh and is the sub and port on your box facing forward? The port needs something hard for it to unload.i would put te port towards the door and maybe sub up.

Edited by Bassink

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Hahahahah that guy has no defense!!! There's no difference in building a box for a 15 or an 18. The box is just bigger in all aspects like net volume is bigger, port is bigger(well depending on sub but usually is) and the cut out for the hole.

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^^^ this ^^^

this box builder sounds like he doesn't really know his stuff.

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^^^ this ^^^

this box builder sounds like he doesn't really know his stuff.

Exactly!! That's why I was thinking he was not happy with the 18 BL. I'm sure if he had a good design and was built right, he would of been happy with the output. Either way this sp4 will do the job. Edited by Bassink

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ok, so i will run a single 3/4" MDF on the box. what should i do for bracing? connect the front/back side/side top/bottom? or just a couple of those?

 

i did order a dual 1

 

to explain my 3rd paragraph: i own a vidsonix 15" sub that ive had for 10 years. its hooked to my computer and i love the clean, rolling, phasing bass it can produce. songs from poker face to kaskade eyes, to disturbed and godsmack sound good. the sub i had (Fi BL 18) totally blew away anything i had ever heard in the higher frequency ranges of bass, such as what kaskade puts into most of his songs. the lows however were another story, lady gagas song just dance had no bass in it. the low bass was kind of felt but you could not hear it, my 15" had more power than my BL. Love game by lady gaga however sounded bloody amazing as it was all high frequency bass.

 

i want to be able to have amazing bumping like on disturbed, god smack, just dance; while at the same time not loose that crazy high end power that i had. I have owned Kicker L7's and those were able to pound the low end bass but were just like the BL but reversed where they were hollow on the higher songs such as kaskade eyes and love game. I feel like i traded low end for high end and as most of my songs are high end i was ok with that but then the BL just ended up not being loud enough even on the high end. i started it off on a ZX1500.1 and then put a 2500.1 behind it and it got quite a bit louder but still not enough. this is why i sold it and ordered a SP4, with my 10" and 8" door speakers and tweets and super tweets the sub just got drowned out.

 

what im looking for is a box that will give me every last bit out of the SP4 that is possible, i want to be able to hit every conceivable frequency that this sub is built for and i want to do it while being so loud you need to time your next breath with the bass...

 

I prefer to build this box myself but i am looking for quite a bit of help on design.

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going over some numbers, if i do .75 the box will be much smaller. it was suggested that i would want to stay around 7 cubic feet, my old box was 5.5 cubic feet and tuned at 44hz. this is the box that i had built for me.  i was thinking for my new box to tune around 35 or 36hz and make 8 cubic feet. my thought behind this was that a larger box would aid in the low notes and a higher tune would help keep the higher frequencies. i have had some input however that tells me i am incorrect about this assumption and i should tune at around 32-33hz and a larger box would only reduce the amount of power the sub can hold.   wich direction should i go?  does anyone happen to have skype or some kind of voip? id love to have an actual conversation about what exactly im trying to do here and where im going wrong.

 

thanks.

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 my thought behind this was that a larger box would aid in the low notes and a higher tune would help keep the higher frequencies.

Nope. Box tuning is a world of trade-offs. No secret magic that can make you hit those 45-50hz like your old box and also destroy the 30-38hz range. 

 

 i have had some input however that tells me i am incorrect about this assumption and i should tune at around 32-33hz and a larger box would only reduce the amount of power the sub can hold.

 

This statement is correct. Except you should tune at wherever you want. But a larger box makes the speaker reach it's mechanical limits with less power than a smaller box. 

 

 wich direction should i go?

 

Wherever you want to go. If it was me I would go for 33hz. But that's just my preference. 

 

i want to be able to kill the lows while still destroying hte highs. i seriously do not want any dead spots.

But no matter what, this isn't going to happen. It just isn't. It's the equivalent of saying "I want a car as fast as a Ferrari that I can also use as a moving van that triples as a vehicle to tow my motor home with."

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The reason why your bl was not hitting the lows was because the box it was in was tuned to 44hz. Most people don't tune that high. Hitting the lows like you want, you should tune to around 33 hz. I say that because then you will still be able to hit the highs quite well.

I really don't think your last box builder knew what he was doing.

I wouldn't worry on the size of the box as much as getting in the right port area! That's more important and we really haven't talked much about that.

If you want to talk you can txt or call me if you like. 810-986-0992.

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im going to let my phone charge a bit and then ill give you a call. i was told for port area that i just need a large enough one to prevent port noise but aside from that it only matters in the realm of tuning. 

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does it matter how large the box is? i originally wanted 8, then i was told stay around 7. how do i know whats best for me, if the sub requires less power in a larger box then does that mean it also makes less noise? should i stay around 7 or go up to 8?

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But no matter what, this isn't going to happen. It just isn't. It's the equivalent of saying "I want a car as fast as a Ferrari that I can also use as a moving van that triples as a vehicle to tow my motor home with."

 

i understand there are trade off but why then can i have a home stereo that is also ported that can hit the lows and the highs equally well? perhaps im not explaining what i am after well enough or perhaps home audio and car audio are different? i would think tho that a ported enclosure is the same whether its a 15" 750W home sub on my computer or a 3000W 18" Fi sub in my truck no?

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from what i just found on-line i need 167 cubic inches of port... at that size i am having a very hard time tuning anything below 40hz... does that port area sound correct?

 

i would like to make this box some what rectangular so i can turn it and face it up, back, or forward to play around with acoustics.

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from what i just found on-line i need 167 cubic inches of port... at that size i am having a very hard time tuning anything below 40hz... does that port area sound correct?

 

i would like to make this box some what rectangular so i can turn it and face it up, back, or forward to play around with acoustics.

Do you mean port area?

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my old BL box had 2 24" long 8" round ports and my builder said they work better and he preferred them over a slot port. im leaning towards a slot port as they seem to take up less space and are easier to build. now knowing about minimum port area it seems that my old box did not have the recommended amount of port?

 

im basing this off of this website: http://www.carstereo.com/help/Articles.cfm?id=31

 

it seems to take Xmax and compute the port area, should i consider this to be accurate?

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yes port area

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You use coil overhang as xmax. Not the 70% BL method listed on the site.

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what is the proper formula then for the determination of port area. im not sure what 70% BL means.

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given what i think i know right now here is a new build: what did i not get right?

http://imgur.com/a/o5MYm

 

Zeyi4UL.jpg

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I based mine off of yours

 

Overall - 27h x 37w x 25d

 

Port - 4.25h x 35.5w x 36L

 

I came up with 7.75 cubes tuned to 33hz with 151in2 of port area.

 

 

Honestly that is great! I'm not sure how you don't think you can get your tuning under 40 hz. I was able to get it easily down to 29hz.

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And we think that 151 square inches is enough?

Could you tell me how exactly to calculate what I should have for port area? it seems that maybe the website I was looking at to give me a hundred sixty seven was incorrect.

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I've tried to use ISD to show me how it's going to react but the program refuses to accept the specifications of the sp4 or the BL so either the program is broken or Fi audio lies about there subs specs. Either way it's useless to me.

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