I am finally ready to add some bass to my car. I don't intend to change my stock head unit ever and I have already replaced my front and rear stock speakers with the Audiobahn's that Red Zman recommends. So now I want to add a sub and an amp to power the sub.

Here's what I got, an MA AUDIO HK798 800W 2 CHANNEL AMPLIFIER and a KICKER COMPVT SUBWOOFER model CVT12

Links:
http://www.audio-n-more.com/thestore/prods/HK798.html
http://www.kicker.com/06/tech-support/manu...20b01%20Web.pdf



What I want is a very clean install and not to lose any trunk space really. I bought this sub specifically because it can fit in an enclosure as small as 1 cubic foot. To save my trunk space I would like to fit my enclosure into the spare tire well so it will rest underneath the spare tire half moon shaped cover.


The manual for the CVT12 says the minimum sealed enclosure should be no smaller then 1 cubic feet. It also gives dimensions such as

Panel A, in (cm)
3.125 x 16.5 (7.9x41.9)

Panel B, in (cm)
18 x 36 (45.7x91.4)

Panel C, in (cm)
3.125 x 36 (7.9x91.4

My questions are:

1) Must the dimensions of my box/enclosure be specific to the measurements above or can the dimensions change as long as I still keep the same volume of 1 cubic foot? (I.E. Could I make a box 6" deep by 20" wide by 20" long?)

2) Since this is going in the tire well what is the best way to do this? Should I line the now exposed metal with anything for a better sound? Should I make the enclosure out of fiberglass or MDF board?

3) How far does my amp need to be from my sub? Or does that matter? I know you can't have the amp power and sub Audio lines crossing or you will get a hum.

I have been doing a lot of research as I knew this project would be coming up on me soon so I do have some knowledge but I'm not a big sound audio guy and I'm not all about having the best, I just want my shit to be done right.

Tibbymat, I better get some advise outta you in here

 

the volume is the main thing... yes the dimensions do change it somewhat. but not enough to notice. just make sure you dont build the box 1 foot by 1 foot by 1 foot. cuz you wont be able to fit a 12 inch sub in there obviously!@ tongue.gif but some people make that mistake commonly enough

 

1. You can have almost any shape you like if it is the same volume of air inside.

When you build your box don't forget to take into account the amount of air the back of the speaker and any internal bracing will take up. I always build enclosures a little bigger when I can to make up for the air space lost when you have everything in the box. You don't have to be exact to the recommended volume.


2. Yes you should line it with some sound dampening material like dynamat or something similar.

Fiberglass would be nice because you get it molded to the space so it fits well and you get more room than trying to fit a square box in your round wheel well. But it will take longer and be more work. Just make sure you have your sound dampening down first before fiberglassing the wheel well.


3. IMO your amp should be as close to the sub as possible, but you can mount it anywhere really.

If you put it further away make sure to use heavier speaker wire so there is less resistance for the flow of electricity. I use 10 gauge wire to my subs.
Running the signal and power wire seperate is the best thing to do. Have them as far apart as you can.


Hope this helps. I was bored so you got the long answer lol.

 

thanks for all the advice guys. I'm still trying to decide what to do about the enclosure. I'm thinking space wise it will be really hard to get an MDF enclosure to have the volume I need unless I make one that is a cylinder shape or a hexagon shape which means more cuts and added possibilities of imperfections.

So it seems I'm stuck with doing some fiberglassing because I have to have a round/cylindrical enclosure to utilize as much space as possible so I can actually have 1 cubic feet of sealed space.

If thats the case I think I can use the spare tire as a good template. I could just cover it with tape or plastic (what is best recommended?) and then fiberglass the bottom and sides of the tire to get a tight fit. If I do this would it be best to have the top piece as MDF or Fiberglass? Will it make a difference in sound quality?

 

Using the tire as a form is a good idea!

Wrap it in tape and aluminum foil. Plastic wrap won't work. The resin for the fg doesn't stick to the foil very well. I would use mdf for the top because fiberglass would have to be thick so it wouldn't vibrate with the sub.

You could always use mdf for the top and bottom of the enclosure separated with bracing then fg the sides.

Like this: Tan is mdf, grey is fg



It was a real quick drawing but just to give you an idea.

 

Since you asked for my input... Don't remove the spare tire. Keep the spare tire, use the inside of it for the mold and keep it in there so you don't end up calling tow trucks. That's all I really have to say about this. Keep your spare tire, it's there for the one time you might need it so you don't have to pay $150

 

^^While I would agree to keep the spare tire in case of emergencies...I also have to disagree.

Depending on how low the car is, spare tires won't work. If I put the little donut on my car, I'm going to be laying the car down on FG before the wheel even touches the ground. Basically when I go on long trips I make sure that I have access to a full size spare, and enough cash to buy a new tire at the earliest convenience. Going to Nationals last year, one of the guys I was driving down with had a universal bolt 17" rim. So if one of us got a flat we'd put the spare on, drive to a tire place, get a new tire on the good rim, put it back on the car and be on our merry way.

Basically what I'm trying to say. If your car is too low to be able to function with a spare, take it out. At the very least you can write it off as a weight reduction.

 

forget the use of a spare tire. My car has none because I have 17" BSA wheels and a veilside bodykit. This weekend I'm installing KYB GR-2's and Eibach springs. A 15" spare tire would destroy my car probably.

But beyond all that. I end up towing cars a lot so I have AAA PLUS which entitles me to as many tows as I want in a year for $96.
The price of one tow is usually more then that. I can tow up to 100 miles free each time I have any car picked up. Trust me, AAA has my back, I have used them three times in one day believe it or not.

So DTN get back in here and give me some real advice.


Tib, I like your idea with the two pieces of MDF and FG in between. I'm thinking all FG bottom and a MDF top may be best tho because I could just form the piece over my spare tire and slide it off. Then I could add inside layers and it would slide in perfect and fit on the spare tire rubber blocks. The slight curvature that the bottom would have would probably have it sit a little tighter on the blocks.

 

OK... IF YOU ARE DOING AN ENCLOSURE IN THE TRUNK WHERE THE SPARE TIRE WELL IS HERE IS THE STEP BY STEP ON HOW TO DO IT... I HAVE DONE THIS ISNTALL A THOUSAND TIMES AS ITS MY JOB. SO HERE WE GO

-RIP APART THE TRUNK
-TAKE OUT SPARE TIRE
-CUT THE JACK MOUNT PIECE OUT.
-GET A COUPLE ROLLS OF 2 INCH THICK MASKING TAPE
-LAY THE ENTIRE AREA OF THAT WELL WITH MASKING TAPE GOING A FEW INCHES OUT ON THE FLAT SURFACE UP TOP
-GET SOME VASALINE (PETROLIUM JELLY) AND GET DIRTY WITH IT.. SCOOP IT OUT WITH YOUR HANDS AND COAT THAT ENTIRE MASKING TAPED AREA WITH VASALINE. (THIS WILL PREVENT THE FIBERGLASS FORM STICKING TO THE TRUNK) AND THE MASKING TAPE MAKING A QUICK REVERSE ON THE INSTALL WITHOUT LEAVING A MESS.
-TAKE YOUR FACTORY TRUNK FLOOR AND PLACE IT ON A LARGE SHEET OF 3/4 INCH MDF AND TRACE IT OUT. THIS WILL GIVE YOU A PERFECT FITTING TOP PIECE. **DO 2 OF THESE**
-PLACE THIS PIECE IN THE TRUNK AND FIND THE HOLE SIZE FOR THE TIRE WELL.
- CUT OUT THE HOLE FOR THE SPARE TIRE WELL
-PUT THE PIECE BACK IN THE TRUNK
- GET FIBERGLASS MATTING, RESIN, AND HARDENER, MIX YOUR RESIN AND HARDENER AND THEN LAY YOUR MATTS DOWN AND GLASS AWAY. FIBERGLASS OVER THIS 1ST PIECE OF MDF AND INTO THE SPARE TIRE WELL. MAKE SURE IT SOAKS RIGHT THRU. DO 2-3 LAYERS OF FIBERGLASS TO MAKE IT NICE AND STRONG AND AGAIN **MAKE SURE YOUR RESIN SOAKS THROUGH THE FIBERGLASS MATTING**
-WHEN THAT IS HARDENED (GIVE IT ABOUT 3 HRS DEPENDING ON HARDENER TO RESIN MIXTURE) DRILL A HOLE TO FEED WIRE THROUGH THE BOX AND SEAL THE HOLE WITH SILICONE.
-TAKE THE 2ND MDF FLOOR PIECE AND COVER IT WITH CARPET OR WHATEVER YOUR HEART DESIERS. (DO THIS WHILE WAITING FOR THE GLASS TO HARDEN
-CUT THE HOLE FOR YOUR SUB
-USE SILICONE CALKING(SP?) AND CREATE A SEAL AROUND THE PERIMETER OF THE LARGE HOLE YOU CUT ON THE FIRST PIECE THAT IS FIBERGLASSED IN WITH THE CAR. **DONT BE STINGY**
-PLACE THE 2ND MDF PIECE BACK IN THE TRUNK AND SECURE IT DOWN TO THE 1ST PIECE THATS IN THERE. MAKE SURE YOU HAVE IT SEALED BETWEEN THE 2
-HOOK THE SUB UP WITH THE PRE INSTALLED WIRES AND DRILL IT IN PLACE


*VOILA* YOU HAVE A LITTLE BASS IN YOUR FACE


hope this helps. if anyone has questions or concerns please ask!

 

Make sure to put some sound dampening down first though. Fg next to metal is going to vibrate and rattle.

Just put the dampening down first then follow what tibbymat said.

You could also use a layer of heavy duty aluminum foil instead of the vasaline. Just make sure it is completely covered and you can hold it in place with some spray glue.