hey peoples

I have 3 three issues but to start off here is my system

Car: BMW 325i (e46)
Head Unit: Nakamichi CD400
Amplification: xtant x603 (3ch Amp - 2x75w + 1x300w)
Front Stage: a/d/s/ 346is.2 (6" Components)
Sub: a/d/s/ 312rs.2 (12" Sub)

I have had my "SQ" system installed for about 5 months or so and it is pretty much what I expected. The sub and front stage blend very well and compliment each other well - you rarely notice the sub behind you except for extremely bass heavy songs ...

1. Sub

The first problem is with the sub, I noticed that when I turn off the front stage completely and listen to the sub by itself it sounds like it is hitting its maximum excursion (probably not saying it correctly) it sounds like a weird rattle and whistle mixed together. You don't notice it much when you have the front stage on and/or when driving. But it is really starting to worry me and annoy me.

I am wondering whether I am giving the sub enough power or whether something might actually be wrong with the sub itself...

2. Rear Fill

Quite simply I want decent rear fill that I can run off my head unit or maybe a small amp - what could you suggest?

3. Front Stage

The other problem is that my splits seem to be lacking a lot of midbass that I really expected out of these splits (they have been sound deadened) also the 75w provides more than enough volume for me but I just want more midbass out of them ... Now I have heard a similar system when I was in canada only difference was that he was running his 346is of x604 bridged (so feeding either side 300w each). Also he had the older previous 5 series.

How can I improve midbass performance?

Should I get another amp - xtant x604 4ch 2x300w - to power the front stage then bridge my 3ch amp to give 300w to each sub voice coil?

thanks
BMW_XTC

have a read of this... http://www.installer.com/tech/tight.html
it may allay your concerns.

1. Sub

What type of box is it? Is it sealed properly?

thanks guys for the quick reply ... very informative and helpful - funnily enough now that I think about it when I listen to the system normally the bass sounds a lot better and almost sounds cleaner with the front stage on than without the front stage on - it just sounded like something was wrong with sub ... so you don't think I should worry about the whistling and rattling noise?

it is a sealed rectangular 1 cubic foot box and I am pretty sure it is sealed properly - i had the box built by GL Pro in melb - is there any way to check if it is? Also the box size was the smallest recommend enclosure size if that makes a difference

Gently push the sub in, if it sprigns back quickly it's sealed, if it takes a while it's got a leak, or somethign along those lines.

reverse what you said and you'll be on a winner

are you sure its the sub rattling???

might be best to move the sub box to a carpeted location outside the car then play it

at large excursion does it rattle, if so it might be moving to its limits

check air leaks and box flexing/rattling

once you have eliminated the box and sub put back in car and test again

is the sub box mounted securely to the car. Is the mounting system rattling??

if you still hear the rattles and other sounds not attributed to the sub then you have to sound-deaden.

adding mass to the boot lid and rear quarter panels can help greatly. Products like stinger road kill and the like will help.

the bars that hold the boot lid open tend to rattle a lot. One solution is to tape the bars so you add mass to them to stop them rattling. Electrical tape works well plus wrapping foam around some of the bars can help.

last is the bumper and number plate. CHeck the bumper to see if its rattling. This isnt very common BUT the number plate is one of the biggest contributors to noise and rattles. Adding mass and securing the plate to the car is critical. Noise dampening sheets will help dramatically.

good luck

Wrong. If the box is sealed, when you push the cone in, you are very slightly pressurising the inside air of the box, and it will want to return to normal pressure, hence it pushes the cone back out quickly.

If the box has a leak, when you push in the cone, air will be pushed out of any leaks. When you let it go, to return to normal position, the air must again be sucked into the box, which is why the sub cone will have a delay to return to normal position.

A leaky box could be the cause of your whistling sound, from the sound of being sucked in and out of the leak. when your pressing in the cone, have a bit of a listen with your ear up to the edge od the sub and see if you can hear the leak as well.

With the rear fill, well have a look in the back of the car and see what mounting locations you have. What ever diameter locations you have determines the best speaker to use for rear fill, be it 4 inch, 5, 6 or 6 x 9.
The speakers don't have to be expensive. $100-200 for a pair of two ways is plenty.

Front mid bass. its hard to boost mid bass from front speakers, especially if they are in the front doors. Problem is that no matter how much sound deadening you have in the doors, they are basically a big, leaky, crap enclosure for speakers hence the pos mid bass performance.
The only way I know to reliably boost mid bass/bass from front door mounted speakers is to build an enclosure inside the door for the speakers. A very hard task given the wind up window and shape of the door and depth. The best way to try is with starm water pipe fittings. A large 6 inch pipe fitted with a flange to mount the speaker then sealed at the back. Then, run 2 inch or larger pipes out of this along the bottom of the door making sure the internals all miss the pipes. Glue it all up with that pvc glue retic guys love and spray abundantly with sound deadening.

Tough job, but its worth it. The effect on the mid range/bass speakers is huge.

this idea of using a 6" pvc pipe sounds a lot easier and beneficial than sound deadening the entire doors, why doesn't everyone do this ? it sounds too easy .. also there is little risk of water damage

Because sound deadening also has the benefit of reducing external noise.