One of my friends had 2 Kenwood subs in his car and made 143db. This was in a 92 model corolla or somethin. Anyway I was told that the exact same set-up in my car, which is a VL, would be lucky to make 100db.

Does anyone have any comment on that????

I have been told that firing subs backwards in a hatchback increases SPL levels..

43db seems extraordinarily large to me though..

whoever said it would be lucky to make 100 is having you on, but you do get better SPL in a hatch.

There is quite a big difference in having subs in a hatch compared to a sedan. My mate has a 1 10inch sub (its only a cheap one) in his corolla hatchback, and ive got 2 10 inch cadence subs in my VL and his seems to be alot clearer and sum times louder. This is most likely due to the restrictions of the back seat in the VL compared to the open cabin in the corolla.

i have a single 12 in my coupe, using 350wrms, its has done a 137db

hatch does increase SPL, but not to the extent ur thinking, u would prob get around 135ish

in a hatch you get bass loading of the back window by facing the subs backwards and slightly upwards. also a VL had alot more cabin space than a corolla. and thirdly they are in the boot, with a seat and some metal between the subs and ur ears. But postman is right 43dB is a bit far out.

100db? Road noise is like 110db.

My mate has 2 15" subs running off a 1000w clarion, in a little alfa romeo. It's never been spl'ed officialy

QUOTE (Memphis @ Oct 3 2003, 02:27 PM)

My mate has 2 15" subs running off a 1000w clarion, in a little alfa romeo. It's never been spl'ed officialy

your point?

QUOTE (hi_lux @ Oct 3 2003, 02:30 PM)

your point?

my doof is better than your doof


ahhh anyway.

one of our cars did a 154db with 2 10"s at last years jamboree in a Daewoo Matiz

who cares how loud it can go, how loud can your ears take before you go deaf?

QUOTE (warrior_350 @ Oct 3 2003, 03:41 PM)

who cares how loud it can go

True that.

anyytihng constant over about 130db is detrimental to ur hearing

Sound quality is more useful than loudness!

From what I've seen, a sub in a hatch tends to be louder inside the car, but quieter outside (in anything but complete silence, you can't hear my sub outside, yet it's too loud to listen to inside).

And a sub in a sedan tends to be relatively loud outside and, well, reasonably loud inside.

Just what I've seen....

Its all in the design of the box and placement...although a general rule of thumb is that sedans are harder to get big spl out of. Just as an example i did 146.2dB out of a single 12" in my excel hatch with about 500wrms..... a mate of mine did 147.9dB in a camera sedan with a very old 15" alpine and about 700wrms.... but i am not in to the old spl game anymore.....took me about an hours work to build a box and rip the gains up to get the 146dB...has taken me much much longer to get the car setup for sq (spend an hour atleast on tuning before a comp)

With the whole defness thing...i have been in a car that did 157dB without any hearing protection... because it is sub bass @ 50hz the wavelengths are very long and do not damage your ears.... where as if u did it at 1000hz anything over 120dB would cause irraversable hearing damage

QUOTE (Spec83 @ Oct 7 2003, 09:00 AM)

Its all in the design of the box and placement...i did 146.2dB out of a single 12" in my excel hatch with about 500wrms..... a mate of mine did 147.9dB in a camera sedan with a very old 15" alpine and about 700wrms....

yes it is about the box design and placement, for example you'de get much more sound out of a ported box than you would out of a sealed box, maybe that's why ur mate only got 147.9dB from 700wrms (which is crazy n e wayz).

it is said that you can get twice the sound out of a ported box that from a sealed box. Then a larger sealed box will also make more sound than a smaller sealed box. (it's really all too much to worry about, either way it'll sound fine)

my only worry is if the sub is made for a sealed box or a ported box, if you match that there's nothing to worry about cause it'll b at it's best then.

That is true... with my old pg sub i was doing 140db with a 2.0ft^3 box sealed..... going to a slot ported box tuned to 48Hz i netted the 146db...my mate with the camera was also running a ported box (wouldnt dare run seriously in a spl comp with a sealed box ). There is a calculator that u can download for car audio australia to see if ya seub is suited for sealed or ported box but u have to remember that what the manufacturer recomends isnt always best. My current hertz air mille 12" sub recomends a 0.89ft^3 box for best opperation.... in this size enclouse the bass around the 60Hz range would be good but there would be nothing down the bottom...i was orignally running 2.1ft^3 sealed and have great bottom end but nothing around the 60Hz range... solution was to port the 2.1ft^# box to about 36 Hz which now gives a very good response through out the sub bass frequencys... somethign that hertz doesnt recomend doing.

Small sealed boxes are louder for spl as they peak around the 50-60Hz region (res freq of most cars which will give greater spl) large sealed boxes good for classical/jazz music as they roll off less around the 40Hz and below region. Ported box is good as u can tune for your desired taste of music and still gain great sq!

a sealed box will also give you a much lower sound output as there is nowhere for the air to go, this slows down how fast the cone vibrates and makes a lower sound.

i lilke the sound of that better than being louder.

i have a 12" sony xplod sub and i'm putting 500wrms max into it. It's in a 1 cubic foot sealed box and it sounds nice and deep.

Yesterday I bought a JL Audio 12W0 12" Sub from JB HiFi....Manual reccomends ported design....

So I'm gonna make up a box with the dimensions it says and face it to the back of my car (silvia)...

Hope I do it OK

Ok well my plan is to have 2x12" Pioneer 1201-C's in a custom box sitting on the floor of my boot facing up. A panel up against the rear seat will house the 2 450WRMS Response amps. As far as I know, Pioneer recommends having sealed boxes. I'm wanting to enter a comp to see how I go once this is done. I'm also getting Boston splits, which will run bridged off my current amp.

Do you think i should have this box ported????

Just depends on what sort of sound u are after.... ported boxes can be made to sound very flat and linear if u tune them right... if not done correctly they are very peeky around a certin band of frequencys (for spl u want this peak freq at the resonate freq of your car to gain maximum spl!). Sealed are much easier to construct and on the whole dont have to be nearly as big as ported boxes...so easier to fit into a smaller space. Only problem i can see with ya install is that if u have the 2 subs in the boot and an MDF partion up against the back seat to house ya amps then not much of the sound is going to go thru the mdf (thats why u make sub boxes from mdf...so they dont resonate)! If your heart is set on putting the subs in the floor u would be best off flush mounting the amps in the floor also... since u cant use the boot anyway.

Also would be a good idea to remove your rear speakers on the parcel shelf (if u have them) to allow a bit more bass into the cabin. Sound deadning the underside of the boot door would also be highly recomended as vl's tend to suffer from vibration cause by the thin spot welds breaking between the sheet metal and the supporting metal ribs.

Nice choice on front splits aswell....bostons go very good!

I decided to put the subs on the floor facing up after a visit to someone who seems to know more than anyone I've spoken to yet. He's in the process of setting up shop and should be fantastic when it's finished.

If I remove the rear speakers then where else could I mount them? Rear doors maybe?

In a good install with a decent front stage/amp and amp/sub setup rear speakers are not really needed ( i only run front 6.5" splits and single 12" sub)..... all they do is drag the soundstage backwards and this is not ideal. The front soundstage should be created so that the bass, insturments and voice sound like they are comming from the centre of your dash inline with the bottom of ya windscreen. This sounds easy but in reality it is very hard to try and get a sub sounding like it is installed in the front of the car (has taken a few boxes plus different subs and front splits to get my setup to sound somewhat similar to above). If rear fill is used it is very easy to distroy alot of your hard work!

I see. I have just finished making custom door pods to house the splits. Maybe i should just leave these as my only speakers. I'm open to all suggestions. Also do you have any idea what sort of SPL this set-up would put out. I'm goin to use a couple of capacitors to help things along as well.

I am guessing around the 130-135db region but cannot tell for sure...just get it metered! Caps are really not needed if the system is cabled/supplyed well in the first place. A bigger battery and alternator (if needed) is much better idea as caps are really just a band aid aproch to fix a voltage supply problem! If using a mono block amp and a small 2 channel to run front stage ya stock alternator should be ok...just get a very decent battery!

I've got 2 rockford fosgate Punch HX2's running off an Audison Mono-block, it did 138 in my VN. Oh the ports load into the boot and the member beteewn the boot and cabin is sound proofed. I'm told it would do high 140's in a small car.

That would be My Camira Spec83 is talking about....For optimum SPL in my car I load the Sub and Port towards the Bootlid. This has the same sorta effect that hatches get with the window load.

i have i 10" sub in a custom box running off an 1100watt coustic 4 channel amp in my hatch. my friend has a lancer with the same amp but running the pioneer limited edition 2 x 12" subs in a box.....i am hitting 130+ dB now whilst he is hitting 122.....hatches definitely make a difference with SPL. its basically because the bass rebounds off the back of the hatch and through the cabin whereas a sedan traps al the bass inside the boot and a smaller percentage off the bass travels through the cabin. GO THE HATCHES.
YAY I GET MY 15" on friday.....ill be bak with the reports of my dB levels then!!

With hatches, what happens is what is called rear loading.

By firing sound at high pressure (produced from your sub pushing air forward) into your hatch you create a body of high pressure. Now, if anyone remembers this from high school.... high pressure systems always move into low pressure systems. And where would a low pressure system be in your car? At the front where you sit of course because it is the furthest away from the high pressure system created by the sub. This means you have ALOT of air moving to the front of the car (given there are no obstructions). So, as we all know sound is vibrations, more specifically, vibrations of the air. Now, if this air that is vibrating is moving forward in the cabin is is pushing other air away, as well as passing is vibration energy onto that air.

All this creates the effect known as rear loading.

Your car is also bigger. You should be able to get alot more sound out of it. Just design a new box and have a play.

The main point is ... does it really matter how loud your subs etc are?
Are you going to use your car as loudspeakers at a professional concert?

Spec83, it's nice to see somebody who knows what there talking about! Top work champ!

I made 133.1dB with a pair of 12s in ported box running off around 400WRMS in a 1990 Ford Falcon...

SPL is all about Physics, but generally, the smaller the space, the higher the dB. After all, SPL=sound PRESSURE level....

What about open air subs????

Also guy of Lateral g has 140+ in his alpine system (car - Proton Satria)

2 Type R 10 inch subs
2 Large Crossovers
2 V12 Amps
i dunno what else

more doof doof for ya roof

and my van made the 157 that spec was talking about. Van large cabin area high spl now figure that one out. it was running six xfire 15s and three 1000d xfire amps.

6 with three amps

one of our cars did a 154db with 2 10"s at last years jamboree in a Daewoo Matiz... ben it did a 147.... same as bodyjar....