I look at this factory amp and I hate how I have to dial most of the sound to the back to even HEAR the dang thing! I miss the 10" I had in my Mitsubishi...too bad it's a 4ohm. I can't run that in there.

I'm possibly looking at how to remove the factory amp and system, new speakers, and such. I'm looking to throw a double-din replacement radio

 

my car didnt have the stock sub in it, wasnt opted in from options. so my 2 cents on what im going to do...

Junk yard, stock box.
Remove stock amp and sub.
Replace with shallow mount Sub 8" 250rms .65 cf needed in sealed box.
Replace amp with thin mount 250rms 2ohm stable amp.
Seal the box and install.

Thus not loosing any cargo space and still get a decent bump. Doesnt need to be like what i ran in old days. In old days I was running 2400 rms amp to two subs in a 125 lb box with a 80f batcap. now talking about a system the ticked off the cops and neighbors let alone would shake your windows and move hair! :-( just talking about it i miss it.

Another thing I thought about doing was maybe grabbing a second stock sub box and installing on the other side of the car and running 2 8" subs if needed for the bump. line the car in dampener to make it less noisy on outside. Then would be running 500 rms total which in all reality is a lot when it comes to a small car like the HHR.

 

There is no room on the other side for the factory box. Also the shape of the factory box would not work anyways as it is a very very odd shape. But what you want to do in the original factory location can work. Add some poly fill inside the box and add some sound deadner to the box itself.

 

would using spray foam inside the box work as well? or is that what u mean by poly fill

 

poly fill is the stuff you put in pillows. you can get it from fabric section of wal mart, jo anns, etc.

im weary of poly fill in a sub box, unless you get flam retardant poly. at competitions ive seen that stuff catch fire. not a pretty site.

i plan on using dampener around that area of the car and on the box.

 

FYI Poly Fill Video Fact vs Fiction (remember everything on the internet is true; lol)

 

I have used poly fill since the early 90's and have never had an issue. It can not self ignite so if a fire started it was not due to the use of poly fill. Now it is possible some of those fires were due to the use of uncured Liquid Nails sealant which has a large amount of solvents in it until it is fully cured. But poly fill by itself cannot start a fire. I guess if they are burping large amounts of power and somehow created a spark outside the speaker that somehow caught a piece of poly fill it could happen but I am not buying it.

You want a .65cft box and the factory box is closer to .5cft so poly fill will be needed for your sub.

I like in that video that he mentions poly fill to be soley to make the sub think the box is larger BUT that it does not help the sound at all. HMMMMMM what does using a larger box do for a sub? A larger box usually allows a sub to play lower and in the case of the box being to small a larger box will FOR SURE help it sound better. So while the use of the fill is to trick the sub the effects of tricking the sub infact do help the sub to sound better.

 

Polyfill for like pillows I believe is required to be flame retardant..much like anything used around human beings to lay on/play with (stuffed animals)...

 

haha tell that to the fair/circus people igottawoody, i sweat i was just smoking a cig one day at the fair and caught my kids stuffed animal on fire that he just won.. lol, but yeah some poly fill has a hire fire retardant then others, is more so what i was looking to say.

07azhhr, i couldnt honestly say what caught fire, i was there for comp but was using a sealed box, the 2 boxes that caught fire in the 10 years i was going had p-fill in them, same box maker actually (not going to drop names). But i know (or pretty sure) one was from a burp that blew his coil cause it to spark, then from there spark turned into fire etc.

on the video, haha. thats why i said (everything on the Internet is true, lol), cause there are a few things in there is contradicts himself with.

However there is a downside to p-fill. You can use TO SMALL of a box and add to much, still creating the sub to think more air, but damaging the sub from not enough air. Normally the rule of thumb when we were at Nitro DB and DB Drag, was only use p-fill if your trying to compensate .25cf-.65cf. If your trying to over compensate for more then that of cubic ft, you need a bigger box or to port.

option two, IMO SUCKS.. you can PORT and P-Fill. Now again that IMO of sucking just because I dont like the sound of ported boxes. Slotted and sealed, not ported. But when all else fails, port and p-fill.

oh yeah, ill have to find the link again in my history, but the stock box, with no mods to it, came .62cf (still not a lot of air to mess with)

 

I put in a 4ohm 8" JBL-GTO804, but I also ran it off an external amp just for the sub but there is plenty of space under the floor in the back.