Hello.

I have been reading for the last 30 min through various threads and nothing seems to come up with this concept.

I have a VL Commodore and I have dynamatted the boot and the front doors.

I am getting major bumber rattles and my parcel shelf is going crazy.

My question is, when I have my sound system at a fairly low volume the bass sounds quite nice and I am very happy with it. When you turn it up to a very loud level the " punchy " sort of bass sounds very distorted and is not clean what so ever. I would imagine with a pretty high end sound system the volume wont have an effect on the sound quality it should just get louder and louder ( WITHIN THE SOUND SYSTEMS LIMITS )

When I play the rap - rnb sorta music which are alot of the time just tones, am I right to say that it is resonating with the parcel shelf and all the rattles so thats what makes it sound good??, but its when I get a punchy sound the system sounds like crap and sorta apposes the rattles to cancell out the bass???

The sub is a DD9512 and its running off a E-Audio 3000d, should I perhaps turn the frequencies down on the amp to get it to do just low and not such high frequencies??

Anyone with more understanding to this could you please help me

Thank you very much
Stefan

I think you are discovering what many people know from experience - older commodores rattle a lot.

The only way to stop it is to find each thing that rattles and fix it down tighter or apply deadening/foam to stop it rattling so much. one thing at a time, until it's all fixed.

if your after sq not just bass, i would try crossing over the sub at about 60hz... this helped abit with my rattles, i have a VL as well. but you are never going to get it to stop rattling, also a big problem with VL's is they have a solid thick wall between the boot and the cabin, which 1. stops them being overly loud. and has abit of effect on sq

as for the distorting part, what type of box is the sub in and what is it tuned to? and what type of recordings are you listening to? mp3's? because the distortion might be on the media you are playing.

you cant do much about the outside guards rattling, short of stuffing them with foam ect, which prob isnt the best idea. they are just plastic attached by a few screws. apart from turn the sub down abit or turn the fronts up so its less noticably.

Hello,

I will try crossing my sub over at a bit lower frequency. Also I am using proper recorder material, it is clean and a non mp3 format.

My wall behind the back seats have been cut open in a triangle shape, it is very large opening. I have 2 large triangle openings. I also haven't got rear speakers so they are empty 6" speaker holes that go into the boot as well. The seats sit over the cut wall.

The sub woofer is in a 2.5 cu foot box, and is tuned to like 40 or 45 Hz on of the two. It was recommended by DD Phil :]

I think I will chuck heaps of foam under the rear shelf and maybe even have a large bolt or 2 going through into the boot to bolt down the parcel shelf.

Well I suppose if everything is installed right ( including stopping rattles ) it will sound a lot better. But is it possible for the rattle to distort the more "punchy " sort of music??

Thanks for your help guys :]

take your time and change one thing at a time.
Start with the boot, so switch off all your front speakers and run individual tones from 40hz to 250hz, every tone may cause different parts to resonate at that specific tone, use a garden hose with a small funnal on the end to locate specific rattles with the other end to your ear, the funnel being small enough to probe into a open door if need be.
THen after all that which could be ages , switch the sub off and power up the fronts , do the same format for the fronts.
Then run the sub and the fronts at the same time for a final clean up.
Get a mate to help u.
IVe used that method and u can identify problem areas fairly quickly, fixing them is another story..............cors

change the box.. 40 - 45hz for an sq aligned ported box is too high.
DD specified that to go louder, but that doesn't necessarily equate to good SQ.

I'd look at changing the box in the future and tuning to around 30hz

apart from that, you're twiddling knobs trying to get a quick fix where you need to sort out the mechanical side of the installation first..

DD spec there boxes to be tuned at 40hz, which isnt ideal for sq, but is ment to be were they sound the best (note i havnt tryed this myself) i would also try making the box abit smaller say 1.8-2cft, and see if that helps. i think what you might be in countering is group delay.

A subwoofer should sound the same at any volume (within its limits). You are either hitting the limits of the subwoofer or amplifier, and either one is audibly distorting.

Hello.

hmm.. Yes, the subwoofer should sound the same at any volume, but I am not really pushing it too hard for it to start sounding off. My subwoofer is facing backwards and is about 10cm's from the rear of the car, so its quite close, do u think this plays a roll perhaps??

I know DD are made to get loud and I thought 2.5 cu foot was good for the 9512, any ideas for how long/big the port should be for a tuning freq of 30 HZ??

Thanks for your help guys.

Stefan :]

oh sorry forgot it was a 9512 u had...send phil an email, hes got alot of box designs already made, and should be able to help you out with measurments.

Thanks for your help guys.

I suppose I just need to pay A LOT more attention to my installation.

Also one more thing when I turn my system up to REALLY high levels I get a bit of light dimming, my power/ground cable is 1/0 gauge and my battery is a 33kg 950CCA rated battery.
Any ideas??

Is it adequate to have the ground come from under the seat belt bolt??

Also is it ok to use 0 gauge lugs that arent as thick as them stinger 0 gauge lugs ( REAL thick buggers )??

Thanks for your help guys

the lug's thinkness should matter alot aslong as they have a good clean contact. is the ground cable your talking about from the amp? if so u then u should upgrade the earthing on the battrey as this will help. my headlights dim no matter if my stereo is on or not. (when i rev they go abit brighter) but it dosnt dim because of music. have a read though this http://www.mobileelectronics.com.au/forums...&hl=dimming

Hello.

hmm I have upgraded my battery to chassis with 0 gauge, I have grinded paint off under the seat belt, and I have grinded the bolt and everything. I havent upgraded my engine ground as I have NO dims what so ever when my car is running, everything is fine. just when my stereo is blasted I do get dims.

Does it really matter about upgrading my engine grounds, as my main current draw is my stereo and that has adequate cables??

Thanks guys :]

I have upgraded all the earths, and when the sub hits hard, the lights dim - engine on or off. I wouldn't be too fussed about it - it probably the alternator reaching it's maximum output on the loudest bass.

bigger alternator will help there.

my system plays most music quite well without rattles (with exception to one of the songs on the chesky disk) ....last night i was playing Ministry of Sound - Sessions 4 and didnt have the volume overly loud but it was shaking the door trims so much it was crazy

Get rid of the VL - either that or spend the market value of the car twice over in deadening material.

Hello.

Well its not that easy I cant just get rid of my car. too much work has gone into it all ready.

Would it help putting some sort of legs on the sub woofer box to make the transfer of vibration not be so violent on the car??

I have dyna matted my parcel shelf and have also dynamatted abit of my wall behind the back seats.

Still sounds iffy.. I am going to braise the box VERY soon as I have noticed box rattles, with the boot open, this would add to noise. I am thinking of using big bolts and nuts to braise the box, is this method ok??

Thanks for your time guys, it does help me.

Stefan :]