Loudest Commodore - Sedan or Wagon?

[holdenboy]

Alrighty reading the other thread started by vt josh i decided to run some tests as i had everything i needed right here and some spare time.

The sedan is a VS Executive
The Wagon is a VR Berlina





The Equipment:

Subwoofer: eBay "American Boss" 12" DVC 4 ohm Subwoofer, rated at 500wrms on a really, really good day.
Enclosure: 1.1 cu.ft. Sealed, 16mm MDF.
Amplifier: Cutting Edge CE2200P, 2 x 200wrms / 1 x 600wrms at 4 ohm. Will be wired to 2 ohms bridged.
Battery: Optima D31 yellow Top with variable PSU attached - set to 13.8v
Source: Test tones on iPhone using 3.5mm to RCA cable.
SPL Meter: Termlab - sensor on P/S of windscreen (DB Drag) or close enough.

The amp, battery, iPhone and Laptop were all outside each car, to make it easier to swap in between cars.




Testing Procedure:

* Put sub box in centre of luggage area facing rearwards, run a sweep at full volume and find peak frequency.
* Wait a few minutes for sub to cool and play that frequency at full volume.
* Repeat trying different box configurations etc.



Results:

First up i tested the wagon, found it peaked at 49hz:


1st run, box in centre of luggage area facing back: 130.5db
2nd run, box in centre of luggage area facing up: 127.5db
3rd run, box in centre of luggage area facing forward: 130.2db
4th run, box in the centre of luggage area but placed right at the back (5cm from tailgate) to add more loading on the sub: 131.1db

http://i730.photobucket.com/albums/w...r/DSCF0807.jpg


So thats about as much as i could get out of the wagon with that gear.


OK so the sedan, same procedure as the wagon:

1st run, box in centre of boot facing back: 129.7db
2nd run, box in centre of boot facing back: 129.2db
3rd run, box in drivers side corner of boot facing diagonally towards tailight: 130.0db
4th run, box in centre of boot about 10cm away from boot latch to add more loading on the sub
AND put the ski port down: 134.3db:




I was pretty shocked with the score so needless to say i did two backup runs without touching anything but the "pause" and "play" buttons on my iPhone. The score was repeated twice and i even put the box back into the wagon and recorded a 131.1db.

EDIT: To all those that know what a Termlab readout shows, yes i know the 131.1db score shows a crapload of clipping, whilst the 134.3db dosent, dont ask me why......both scores were set using the same gear, setting etc. just different cars.

[alien]

4th run with sedan, is it possible to do it with ski port up? (How many people would actually have street vehicles.

A test against a wagon with test 4 and sedan with 4 with ski port up would be what not comeptitors will usually want to compare.

[holdenboy]

With the box about 10cm away from the tail-lights and the ski port up?

The first run is similar but the box would have been 20-25cm away.

[KAL SPL]

I could have told you the sedan would be 3db louder than a wagon with a single 12" , the whole boot acts like a bandpass

How do you think we did 146 in a 323 sedan with a single 10"

[aazn]

with this data showing.. does it mean it only proves that the enclosed boot setup is better for SPL but for volume, will the wagon still come up on top?

will the wagon top the sedan in SQ?

[lunchbox.inc]

you kno, this is actually REALLY interesting!can't say i'm entirely surprised, altho i would have still thought the wagon would come out on top, i'd love to see the same tests done, with a slightly larger setup, perhaps a basic 2x 12" ported setup? as i think thats where we'd start seeing differences, but again, thats really surprising!

good work holdenboy!

[holdenboy]

Yeah it is surprising to say the least, but it just shows you how important (over 3db) opening the ski port is when you have an everyday setup in a Commodore sedan. Yes now that you mention it Kal it does act like a big bandpass box....whereas the wagon acts more like a huge hatchback.....better subs and more power would probably see those figures get closer, more again and i'd say the wagon would be ahead by a 1-2 db.

[acarmody]

I always drive with the centre seat (ski port) down because I believe it is louder, by a fair bit too. Since 99% of the time I'm the only person in the car it isn't problem. Though I do put it up when I part in public because you can see big colourful power cable and I don't want my stuff stolen.

If I was down your way I would lend you my two ported boxes to compare the sedan and wagon, but alas.....

i can really believe the ski port thing too, because I would think the back seat foam would act as a massive sound dampener.

EDIT: Maybe if you get a chance Holdenboy, take off all the backseat backrests and lay them down, so there is no backseat foam between the sub and the meter.

[holdenboy]

Its all good, i'll have full access to the Termlab meter from now on anyway......and the VS will be here for another month or so, will look into doing a pair of 12s in a ported box or something. Not too sure if the neighbours will like me though

I dont want to go modifying the interior too much, just the usual things you can do in Street classes to increase your score.

[HCVP]

I wish i had neighbours doing what you were doing

I think i may have contributed a little to that thread getting sidetracked.

I was of the opinion that a smaller car, will always be louder using the "same components"
Based on a sub's main purpose being to move air. The less air it has to move, the more sound pressue it can create, unless it has obstruction.

I didn't mean to start any arguments in that thread, all i was trying to get at, was that if you were interested in becoming involved in SPL events, then it would be favourable to have a car that works to your advantage regardless of the components, or your budget. (much like your CRX idea)

It will be interesting to see the results using some more gear, and too see the differences as both vehicles become louder.

[holdenboy]

I think the layout and shape of a sedan will almost always make "entry level" gear louder when i small amount of common sense i suppose is used (folding down the ski port). As Kal SPL said the ski port acts like the port in a BIG bandpass box, increasing efficiency ....whereas i cant really replicate anything like that in the wagon. It was only 0.2db louder with the rear bench seat folded down, couldnt get any higher than 131.1db no matter where i placed the box, as you can see from the photos i was contemplated whacking a 4" port externally and seeing the results, but i think the box is a little too small.

I also got bored and made a euro style box, 10" PVC pipe from the old box with a 10" Response 125wrms sub on one end, then MDF plugging the other end with a 6" port haha. I think the sub really dosent like it though, cant get a reading on the windscreen with it.....Needs a DD 9910 or something, and that CRX you mentioned

[KAL SPL]

Echo and 2 9510s

[acarmody]

Who needs paper shredders? LOL.

[holdenboy]

Yep i remember that car.....what was its best run?

Was it you guys that came over from WA for Final Battle one year and used a hire car to compete?

[acarmody]

Using a hire car, HAHAHAHAHA, thats bloody gold.

[KAL SPL]

I used a hire car in every state , always had to be an Echo , it wasnt 'guys' , just me , took different people on the trips with me but , even took my Mum to Final battle and Aus finals in 04

[holdenboy]

Yeah i was only just getting into DB Drags then so didnt know too many people, just knew you had hired a car for Final Battle.....must have been 04 when i was there.

[AmmoJammo]

EDIT: To all those that know what a Termlab readout shows, yes i know the 131.1db score shows a crapload of clipping, whilst the 134.3db dosent, dont ask me why......both scores were set using the same gear, setting etc. just different cars.

its not clipping, its most likely as a result of roof flex.

I'm still not entirely convinced by these results...

having played with a single 12inch sub in a BA Falcon wagon, doing ~146dB, I haven't seen a sedan anywhere near this with similar gear.