Hey peoples.

Just thought I would ask your opinions on my score. I have 2 Crossfire BMF W12D Subs running on a Crossfire BMF 1000D amp @ 1 ohm

My box is about a 170ltr (2.9Cufeet) in size and it is tuned at 40hz.

I had my first ever SPL comp with my first ever stereo and I scored 142.8 DB

And I think wot makes this score acceptable is that my car is an AUII Ford Falcon

Wot do u guys reckon?
Also I need some help with porting. i don't totally understand the concept is generally a higher porting frequency going to give me better SQ and frequency response??


Regards
Aaron
(NEWCASTLE)


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Crossfire BMF 1000D @ 1 ohm
2 x 12" Crossfire BMF 12D's
Crossfire TEK 75.2 Amp
Blaupunkt Overdrive ODca650 6 1/2" Splits
Pioneer DEH-6450 CD Tuner

Not a bad score in Street, not a bad score at all, my advice is go see Pepe at Nova car Sound, he will fill you in about porting frequencies.

Tuning your port to a higher frequency is not going to give you better SQ and frequency response, as you tune the port to a higher frequency you will find the box output will increase around this higher frequency but at the cost of lower frequency response, the rule of thumb is higher tunes (45Hz plus) give good SPL at the expense of SQ.

Its a generalization but most SQ heads prefer boxes tuned LOW, low tuned boxes in my experience have more "impact" than higher tuned systems, even though they may not meter as loudly.

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TEAM DD "In the Lanes, takin names"
Project "Full Effect" coming soon - Street SPL!!
SPL King Wagga 2002/SAS 2002
Broken window/hurt hand Wagga 2002
Best 158.4db from 2x DD9515's on TERMPRO (SAS 2002)

Thanks

Yeah i know Pepe, I might just go and see him.

Also I am running **** power. I have standard battery running 4guage Power only
but I bought a stiffening Cap yesterday.

I will run 0 Guage or something like that later when I get some money

Also I am getting a PRO boot install done by me and a Friend who is a car installer. and the subs will be closer up near the seats. I will still be rear loading the subs, but at the moment my box is just sitting in the boot right up near the boot/tailgate. So with the new install the rear loading will not as close.

Am I going to lose HEAPS? like 2 or 3 DB?

Cheers
Aaron Glover
(Newcastle)

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Crossfire BMF 1000D @ 1 ohm
2 x 12" Crossfire BMF 12D's
Crossfire TEK 75.2 Amp
Blaupunkt Overdrive ODca650 6 1/2" Splits
Pioneer DEH-6450 CD Tuner

you may even gain SPL, some poeple find that a reasonalbe gap between the subs and the tail of the acr gives best results, from memory around 15cm-45cm depending on the car, i can't verify this having never owned a sedan.
[edit:oooppsss i've owned 2 sedans, but they were mini's so they don't count]
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'96 Mirage, currently resembling a tin can
uninstalled: Rockford RFX9300, Focal 165W3's Vrx 2.150 & 1.500
Power by: HERTZ audison OPTIMA StingerAerpro
TEAM AUDISON

[Edited 1 time by Mr_Bob on 30 September 2002 at 13:05]

yes, it depends on the car, but in my car (which is a hatch though), I GAINED 0.5dB from as close as possible, to 30cm away

your car may be different though

as far as tuning goes, with most subs, tuning LOW sounds best

(but not making the box so large it plays flat to 30hz outside the car, which wouldn't sound that great..)

for most street setups, tuning in the high 30s-50hz range peaking at 50-60hz range is most common

the tuning depends on the subs, box size and the resonant frequency(which depends on the car, box position etc..) and so on..

you'll generally find that tuning high - tuning really close to your cars resonant frequency is not as loud as tuning a bit lower

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- A proud member of Team Gates - A proud supporter of the CAA SPL project

[Edited 1 time by Bassaholic on 30 September 2002 at 17:23]

the face of my box was exactly 30cm away from the tail wall of the boot on both test runs yesterday. box tuned at 39.95hz (from what winisd tells me) on 1st run then 41.3hz on second run, both hit at 52hz. I measured the 30cm exactly just so I have a benchmark to go with for next time when I have a chance to play around with distances.
http://www.installer.com/tech/aiming.html

I found this article interesting, it suggests that as close to the back wall of the boot is best as to avoid cancelation

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Car: '90 Nissan Pintara (sedan)
Headunit: JVC KD-SX750
Fronts: TotalRecoil Carsplit.6
Frontamp: Alpine MRV-T301
Sub: 2x DVC 4ohm 12" Alpine Type-R
Subamp: Lanzar 2000D
SPL: 145.4db (Doran Test Day - 29/09/02)
"If its not quick, may aswell make it slower"

[Edited 1 time by Andu on 30 September 2002 at 16:29]

that score in a sedan in street is pretty impressive, but im sure there is more in the system.

ive read a few articles and done some testing, a commom approach is to rear load by as little as 50mm to the rear of the car (as mentioned, this small distance reduces cancellation), while other articles say that the distance between the subs and the rear of the car should be the same as the distance from the subs to the microphone...

i think that the best way to be sure is to TEST!!! every car and every system is different... have fun!!




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MEMBER OF SINISTER MOTORSPORTS CLUB
1991 MX6 Turbo
Kenwood
MB Quart
Alpine (Selling my MRV-1005's) :(
MTX
Kicker (Sold my S12L7's) :(
2nd place: Supernats 2002 (Super Street 1-2)
148.2dB and Rising!!

that score in a sedan in street is pretty impressive, but im sure there is more in the system.

ive read a few articles and done some testing, a commom approach is to rear load by as little as 50mm to the rear of the car (as mentioned, this small distance reduces cancellation), while other articles say that the distance between the subs and the rear of the car should be the same as the distance from the subs to the microphone...

i think that the best way to be sure is to TEST!!! every car and every system is different... have fun!!




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MEMBER OF SINISTER MOTORSPORTS CLUB
1991 MX6 Turbo
Kenwood
MB Quart
Alpine (Selling my MRV-1005's) :(
MTX
Kicker (Sold my S12L7's) :(
2nd place: Supernats 2002 (Super Street 1-2)
148.2dB and Rising!!

one thing to keep in mind, that if your subs are *really* close to the back of the car, then it starts to work like a (misstuned) 4th order band pass box.. in some cases that may help, in others it may not

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- A proud member of Team Gates - A proud supporter of the CAA SPL project

try firing them str8 in to the cabin

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- 2nd S3-4 Supernats 2001 -
- 1st SS3-4 Final Batle 2001 -
- 1st H W D SCS 2001 -
- 1st 601+ & Loudest Over All Summernats 2002 -
- 1st SS3-4 Wagga 2002 -
- 1st 601+ GLO 2002 -
- 2nd SS3-4 SAS 2002 -
- 1st SS3-4 MAS 2002 -
- SPL KING MAS 2002 -

Thanks for all your comments Guys

Well It seems after alot of reading that there is no concisive answer to my questions about the rear loading issue. hrmmm

The idea with my boot install is to firstly look bloody sweet with perspex, embroidery, trim panels, lights etc etc but to secondly be able to use some of my boot again. (Gees who would have thought that a boot is used for groceries heeh)

If any of you are aware of the boots inside an AUII Falcon then you would be aware of the stupid stepup of the floor pan and the thinning of the width of the boot up in near the rear seat. I will be building a box with about 10 seperate panels moulded into my boot. This will give me some room cause I will be able to stop the box about 50 odd centimetres from the back of the tailgate

I guess I will just beg my car installer (Yes it is still at the begging stage cause I am getting it done real cheap) to give me a box that I can slide up and down my boot.

So I will give it a run in the next sound off. I am thinking about going for the long drive to DUBBO autobahn. hehe I pity the people who live in Dubbo. I hate the place. but hopefully I can get some decent numbers. my last score of 142.8 managed to get me a 2 place up here in Newcastle in SS1-2

I was beaten by a laser hatchback from a Shop up here in Newcastle which had ONE inverted 15" EarthQuake, some bullcrap thing that they imported. They got 146.3 I think. which is a big step up from me. But I will still happy that beat about 50 other cars and many cars with 2 15" sub setups etc. My system was actually the second loudest there. I wish I had gone in the OPEN category cause I beat cars with 3 Kicker Solobaric's and a Ute with a 8 12" Sony Subs in it. O well not to be. But next time I will choose my class better.

If I don't hit 145 with my new setup I will be very pissed off.

Well thanks guy. Oh and by the way does anyone know anyone in Newcastle with a metre. I want to be able to find out the natural resonance of my car and/or where my subs peak so I can just BURP a 2 second tone at the sound offs. None of this sine wave or bass music crap.

Regards
Aaron Glover

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Crossfire BMF 1000D @ 1 ohm
2 x 12" Crossfire BMF 12D's
Crossfire TEK 75.2 Amp
Blaupunkt Overdrive ODca650 6 1/2" Splits
Pioneer DEH-6450 CD Tuner
AUII FORD Falcon Futura
Best SPL Score 142.8DB

hey figjam
that was a pretty good score i was at the same sound off and your system sounded good it was my first sound off as well and what a nightmare i didnt know about fusing and well 10min prior i had to run off and buy one .
i was in the red SSS i achieved a spl of 146.7 with 2x15's in very small sealed boxes i know that these are far from ideal and i plan on improving the whole instal very shortly .