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i have no experience in enclosure construction at all and have been tearing through forums for some helpful advise in enclosure designs. I am pretty confused at this point about some things and was wondering if anyone could clear it up?

I am under the impression that if a certain speaker is in a smaller enclosure that it will handle more power and a larger enclosure will be more efficient (less box rise). so if that is true, will they be equal in spl if they receive the same amount of power (after rise) rather its in a "smaller" or "larger" enclosure?

i have also heard of people covering ports to play with their tuning, is this just a solid cover reducing the height/width of the port? does it have to be as deep as the port or just cover the outside?

the setup: 93 mustang hatchback

150A alt

shuriken bt-60 and bt20

brz 2100.1 (clamped at 1172w @47Hz)

2 fi ssd 12s in a prefab box ~1.6 cubes per chamber ~38Hz

Im pretty happy with the setup as is but i want to get a little more "pressure" from the 12s(didnt really want to sacrifice the

back seat but oh well)

sorry if the questions seem a little on the dumb side, help is greatly appreciated! :D

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Couple things to add to your box size/power statements. While a smaller enclosure can take a little more power they don't have the cooling capabilities as a larger enclosure. On the other hand a larger enclosure is more prone to unloading with less power than a optimal/smaller enclosure.

As for covering ports, that's most likely with multiple aeros (I don't know what you've seen). The only reason I can see to plug the whole port(s) rather than just cover it would be to displace airspace and change the volume of the box to correspond with the change in tuning. Haven't really looked into it at all, but sounds like a reasonable answer.

Not sure where the "dumb" question is though. ;)

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I am under the impression that if a certain speaker is in a smaller enclosure that it will handle more power and a larger enclosure will be more efficient (less box rise). so if that is true, will they be equal in spl if they receive the same amount of power (after rise) rather its in a "smaller" or "larger" enclosure?

First I would suggest you stop worrying about "impedance rise". Every speaker and every enclosure is going to have an impedance curve where the impedance fluctuates with frequency. It's going to happen, you can't avoid it, and you don't design your enclosure around it. There are some things the impedance curve can tell you, but for the most part it's not something the average enclosure designer needs to worry about. Design your enclosure based on desired response.

As for your question about enclosure efficiency, it doesn't have anything to do with "impedance rise" and everything to do with the mechanical damping provided by the enclosure (the amount of "spring" provided by the air within the enclosure). A larger enclosure is generally less "springy" which in turn decreases mechanical power handling and in a ported enclosure can increase peak SPL.

As for "impedance rise" being lower in a larger enclosure....take a look at an impedance graph, you'll notice the larger enclosure actually has a higher impedance at tuning as well as a higher peak impedance (if we keep tuning the same)....and yet, it also has the highest peak output at tuning. How does that work? While the impedance is higher, the driver+enclosure system for a larger enclosure is more efficient and as a result creates more output.

i have also heard of people covering ports to play with their tuning, is this just a solid cover reducing the height/width of the port? does it have to be as deep as the port or just cover the outside?

If they were plugging one of their multiple ports, as was mentioned it would just "block" the port so it didn't function. If they were plugging the port to simply change the tuning of a vented enclosure with a single port, then it would need to extend the entire length of the port.

Im pretty happy with the setup as is but i want to get a little more "pressure" from the 12s(didnt really want to sacrifice the

back seat but oh well)

So you want more peak output? Or more output at lower frequencies?

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Stop reading morons posts on SMD. There has been a recent huge flux of misinformation regarding power and enclosure size as well as the effects and reality of impedance rise.

This of course is not surprising considering the biggest rip off in car audio happens to be the completely useless DD-1

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i had a 91' Fox hatch and i thought it had PLENTY of room for a pair of 12's in a properly designed enclosure. you shouldn't have to sacrafice your back seat at all, even though they are useless. Welcome to SSA. you've come to the right place if your wanting to learn from some very knowledgable guys instead of a bunch of punk kids who think they know it all on SMD. do you have any pics of your car btw? i'm a nut for Mustangs

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<<< Another Fox body Mustang nut. Putting a TFS h/c/i 306 in my 88 this week hopefully (and then a real sub to replace my old JL 10). I'm curious how you think you may have to ditch the rear seat for a bigger box? One of my boxes was 4.5ft^3, and it could have been bigger. I'm also curious to what you think of your low end with that box.

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this was my Fox 91Foxbody001.jpg i loved it. planning on getting another or possibly an SN-95

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yea ill share some pictures soon, its dark out tonight ! shes a four banger but once i get it painted im sure i could turn some heads ^-^. also have an 81 that me and my bro are working on, it has a 306 we took the engine out and replaced all the gaskets and painted it..... it is running stupid rich though. all i have is a 750 to put on top need more like a 650 :/

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<<< Another Fox body Mustang nut. Putting a TFS h/c/i 306 in my 88 this week hopefully (and then a real sub to replace my old JL 10). I'm curious how you think you may have to ditch the rear seat for a bigger box? One of my boxes was 4.5ft^3, and it could have been bigger. I'm also curious to what you think of your low end with that box.

my box is 3.2 cubes now and i could NOT see how i would go any bigger without putting the back seats down. if it were even an inch taller or deeper it wouldn't clear the hatch. i barley have any room on the sides either, cursed hump in the interior over the shocks -.-

Don't get me wrong people tell me its impressive and loud. but i feel like it could do a little more. my main concern is that even before displacement it falls below recommendations. i understand that people do not always follow the recommendations, but ive heard others say that FI's recommendations are a good guide to go by. and the low end is quite. Below 28ish hertz it has minimum output.

Edited by Mtxplod

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i don't have my car anymore so if you could provide the max height, width and depth we could help alot better.

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My 89 Saleen. Never a system in it though, hell I didnt even have a head unit, lol. Car made about 400rwhp on motor only (347, etc etc)

http://s55.photobuck...nt=100_4011.mp4

IMG_10641.jpg

clean1.jpg

Sorry for the Off topic post..............

yeah, i never had a system in mine either. the only thing it had was a headunit and comps. i've never liked the idea of putting a system in a muscle car. if i ever would have put one in it i would have gone with a pair of 8's in a sealed enclosure on maybe 1k at most. Thats just me though. nice car btw Edited by ChILL

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<<< Another Fox body Mustang nut. Putting a TFS h/c/i 306 in my 88 this week hopefully (and then a real sub to replace my old JL 10). I'm curious how you think you may have to ditch the rear seat for a bigger box? One of my boxes was 4.5ft^3, and it could have been bigger. I'm also curious to what you think of your low end with that box.

my box is 3.2 cubes now and i could NOT see how i would go any bigger without putting the back seats down. if it were even an inch taller or deeper it wouldn't clear the hatch. i barley have any room on the sides either, cursed hump in the interior over the shocks -.-

Don't get me wrong people tell me its impressive and loud. but i feel like it could do a little more. my main concern is that even before displacement it falls below recommendations. i understand that people do not always follow the recommendations, but ive heard others say that FI's recommendations are a good guide to go by. and the low end is quite. Below 28ish hertz it has minimum output.

Take out your current enclosure and get measurements of the maximum dimensions you have to work with.

Unfortunately if you're already close to your maximum dimensions, you aren't going to be able to increase both peak output and low frequency extension. Choose which is most important to you.

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The max room i have is 14"H x 36"W x 26"D(+/- 1" on width and depth).

so that renders about 5.7 cubes.

Edited by Mtxplod

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so i was thinking 4.8 cubes before displacement tuned to 40 Hz.... winisd says that ill gain 6 dB at 42 Hz.

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