4-Channel amps

[chuyler1]

Yes...for that ring, it will be visible, but if you cover the whole thing in trunk-liner carpet (instead of paint or vinyl) you would never notice that it was hand cut with a jig saw.

A word of advice...whether you use a router, rotozip, or dremel, always make several passes using the circle jig (2 minimum). The first time you go around you don't want the center to pop out before you are finished. Some people actually recommend routering 3/4 of the board and then using a jig saw for the rest (and allow a sloppy cut by staying along the inside of the channel). Then use a template bit on the router to trim the extra wood off after the piece is removed.

 

[Kid Red]

Ah, now I read your circle post, hahaha. I bought the Dremel and router attachment and that didn't go well. Then I used the Dremel and the circle cutter and that didn't go well, so then I finished with a scrolling saw cut. Oh well, not very perfect. However, the Dremel is making pretty good work of smoothing out the imperfections.

Question tho, the box is about done fabrication wise, and I'm at the making sure the sub fits part. The sub sounds good, nice deep bass, so I'm excited about the end results, but I get a vibration or air rattle type sound accompanying the bass. I'm guessing it's air escaping from the possible spaces between the sub and the ring. How do you ensure a proper seal? My ring surface isn't perfectly flat, and there isn't really anyway to get it perfectly flat as I had to build up one part of it with putty. So, do you use a seal strip or something? I have the speaker gasket on, but the inside ring is short in some areas. I have a door seal strip that I tried to attach to the inside of the ring, but it fell off. Not sure if that would have stayed in place, that it would have stopped the vibration noise or not.

Any ideas?

I've taken a butt load of pics, so once finished, I'll have a nice thread. THe box, since fabricated inside the compartment just barely was removable. Then I had to wrap the fleece around the edges of the box to secure the baffle. It will be quite a task getting the final box back into that compartment. I think I'll go for the painted look first, rather then carpet. I'll use the carpet option as a last resort.

 

[chuyler1]

Honestly, if you ended up cutting the hole so large that you needed putty to repair it...You might as well build a new baffle and glue it over the original.

 

[Kid Red]

We're talking less then 1/8" for the run of maybe 3 inches. THe entire thing is put together, two layers of rings for the baffle and it's already been fleeced.

I just need to know if there's any routine used to seal the sub.

 

[chuyler1]

You could try a layer of foam weather stripping or lay down a bead of clear silicone.

If you push down on the sub and can hear air pushing through a seam in the box or near one of the screw holes that is going to affect the sound. The goal is to push down, hold it down, and have it stay there for a moment before equalizing the pressure.

 

[Kid Red]

Yea, I have the foam, that's what didn't stay in place. I might try that again, though it' quite thick. As for the silicone, where would you bead it (inside the ring or top mount where the sub will rest? And I assume you mean for the bead to dry before putting the sub on top of the silicone so it doesn't stick to the sub?

 

[JCell]

where would be the cheapest place to find this amp Alpine MRP-F450

crutchfield has it for about 300 shipped

 

[chuyler1]

It won't stick to the sub...well it will stick, but it will peel right off later. I'd add a medium sized bead around the edge of the opening then stick the sub in before it dries. It will squash around and some will spill out the sides but that will ensure a better seal. Then you can run an additional bead along the outer edge after it is screwed in.

It's a messy process...but that's why I always recommend using a router with a perfect circle jig. I've been this route and I've never been satisfied with the outcome.

 

[chuyler1]

where would be the cheapest place to find this amp Alpine MRP-F450

crutchfield has it for about 300 shipped

You're not going to find it cheaper unless you are willing to forfeit the manufacturer's warranty.

 

[JCell]

is it worth the price?

 

[chuyler1]

If it fits your needs, then yes.

You can certainly get more power for your dollar by going with a different brand but then you are sacrificing sound quality and possibly reliability.

 

[JCell]

ohhhhh.......awwwwwww

thanks!

 

[Kid Red]

chuyler1- Yea, I used the Dremel and the router attachment and then tried with the circle maker adapter. I've just never done one before and never used a Dremel or router before. I would have made another attempt but I ran out of wood. I figured if I really screwed up I would do another one, but the flaws are so minor. Also, I'm pretty good about sanding out most of my flaws, though it will not be perfect at least I will have it in place while I contemplate another run at it.

Thanks for the tips. After I get the sub in, I then apply the filler stuff to the outside correct? So I will get a smooth finish? Then sand, then paint right?

 

[chuyler1]

What filler stuff are you talking about?

 

[Kid Red]

It's called body filler, it goes on top of fiberglass. It's really thick and is supposed to fill cracks and gaps and pin holes and leaves a smooth thick finish. I saw some at Advanced Auto.

This is where I read about it-
http://www.the12volt.com/installbay/forum_posts.asp?TID=74519&PN=1

 

[JCell]

bondo?

 

[chuyler1]

Ok...I didn't realize you had a fiberglass box...or it just slipped my mind since we were talking about fitting a subwoofer into a wooden/MDF baffle.

So yes, bondo, sand, bondo again, sand again, bondo again, sand again, sand with finer grit, sand with even finer grit, prime, sand some more, prime again, sand even more, and finally paint (usually several coats plus clearcoat).

For the bondo, some recommend thinning it with alcohal so it goes on a little smoother. I've never tried this though. I've only done one painted box and I wasn't very happy with the outcome.

 

[Kid Red]

In the thread the guy mixed the filler with fiberglass resin, so I might try that first. So, expect a lot of sanding I guess

Yea, fiberglass box inside the compartment, and fiberglass fleece around the MDF baffle. Looking at your sig photo, the silver part of your enclosure if what I'm going for.

 

[chuyler1]

Ok. Before you start bondo-ing, make sure that the fiberglassed/fleeced part is structurally sound. You shouldn't be able to push it in by pressing on it and it should sound solid when you tap on it. If it is not, you will need to add layers to the front or back using fiberglass matt and resin or fiberglass-reinforced-bondo.

Once it is thick enough, then start on the bondo. Apply an even thin layer using a spreader (they sell the spreaders at walmart in the automotive section and they are worth every penny...all 249 pennies I think). Let it completely cure (depends on how much hardener you mixed in and the temperature). Then start sanding. Your hands will get tired pretty quickly if you don't have an orbital electric sander or equivalent. For the first couple of passes use 100 grit paper, clean off the area and use your hand to determine if there are any spots that need touching up. Any large pits or cavaties will have to be filled in with more bondo...then sand again. Once you think you're satisfied with it, move to 250 grit paper to remove any sanding lines left by the 100 grit paper. When you're done with that, give it a coat of primer and let it dry. When it's dry you might see places you missed...go back and fill these, sand with 100 (if necessary), 250, and then prime again. Only when the entire piece is smooth to the touch should you start wet sanding with higher grit paper.

 

[Kid Red]

Thanks for the step by step. The spreader, is that the plastic rectangular kind? I have a set of those for the putty. The piece is pretty solid, 3-4 layers of FG. SO I need filler and a whole lot of sand paper or various grades, lol.