I t;line-height:100%">know there are alot of variables, but i was wondering if someone could give me an idea of the kind of Db reading i should be expecting from this system.


Eclipse 5444 deck

Blaupunkt splits (240rms)
Clarion pro audio 6X9's (120rms)
All running of a Response 4X100WRMS amp

Tarantula T4-15 1000WRMS
Michael Angelo 1000WRMS amp

Cadence 2 Farad Capacitor

Extra Info: Setup is in a VT. Gain is turned down on 6X9's to about half to compensate for power. Im not sure on the volume of the sub box, but it takes up the whole wheel well... Its pretty big.....

its pretty difficult to tell, as there is all sorts of variables and rubbish.....ppl ask it all the time...pretty much get that exact same reply....

but we can give a rough (read:very) estimate.....1000wrms??id say.....mmmm low 170s.....

134-136db.

^^ mid 130's would be my guess

Thanks guys. My mate is stressing me out. I have a comp this weekend, and he is saying "what if you don't even make 100" both of us have no idea what 100db sounds like... Got no idea...

All i know is an illegal exhaust is anything over 90db.... so yeah. Thats all i know...

My mate was stressing me out saying what if i don't make 100???
I was like, if i don't, im selling the boot install, and plates, and gonna start over with something else... (new project car) lol.

You guys have no idea how much easier i will sleep at night....
(When i crank my system, i have to hold my ears... its fairly loud...

if it's in a ported box how big is the port and how long do you know?
i would say around a mid 130.
if you crack a 140 you have done pretty well.

If its in a sealed box in the boot of a commodore sedan.
Id say mid 30's. If you went ported you could do into the 40's. Ive seen a BA falcon with a 12inch crossfire in the boot doing 142's.

My 2 cents.

in me mates VT we got a DD 9515 with only 900wrms in a 3.3cuft total ported box, so minus woofer etc its smaller !!!

He got a 136.7, then we unbolted the 2 back seats.. and done a 137.7

Its a ported box.

Port hole is 11cm in diameter.....

About 30cm long....

Not sure on specs of box... will find out if i can... I got it second hand...

you will make it over 100 with no worries at all ive done a 117 with no woofers or amps

mid 130s would be the most logical zone

Sorry to sound like a total n00b....

But is this with a certain frequency? If so how do you do it? Volume on half? How long do you run it for?

Or is it a song?

This is my first "Comp" and its not a real comp, just a bit of fun, so i have no idea. I learn quickly though.

In a comp you "burp" your car for a 30sec period each round your in.

a burp is bass tone only, no music. if your able to get hold of a DB Drag disc (for sale at events) it has 100+ tracks, with i think 40 something through to 80 being set freq tones.

when you do a burp the screen in front of you will tell you what your frrequency is, from that point on, you know what is the best track to play. Track matches Freq

As I always say, 130dB. give or take 10.

Hey Celutin.

What volume should the stereo be at?
Can i keep turning it up to go louder?
Should i fade everything and just have the sub going, or won't it matter if i don't fade?

If u can, disconnect all speakers other than the sub.

Start at low volume then whilst on the meter slowy keep turning the volume up until it stops getting louder......but beware, if your gains aren't set properly u risk frying your sub.

Well i didn't change the gains from when they were set up last (Got it all second hand 2 months old) so one would assume they are ok....

I can phase out everything and just have the sub running.

spl is hard to get in such a big car,

give it a go though, it can be alot of fun by the looks of things

What i have always been told since i got into the sport.

Unhook all other speakers - always.

to set your gain, the way i was told is this...if u dont have a oscliscope (sp)

Set your gain on the amp to 0/off/nothing at all. then with any sound amplifiing options on the head unit turned off (Loud, Bass etc) take your music up to 3/4 of maximum load then slowly take your gain up till you hear the woofers distorting. then turn the gain down to just below that level.

Easier is to use a oscliscope (sp) and turn it up till you see the sine wave clip, then turn it down to just below that point - this is a LOT more accurate.



Wow, ive actually listened and remembered stuff ive been told...

Had the amp "retuned today"

Basically the Sub sonic filter was at 40, is now at 30
The low pass was at 60, is now at 80

This was done by a car audio shop, and he goes "we set all ours to this"
Just wanna ask, is this any good? Should i turn the low pass down a bit to say 70, so i get less midbass......

If you don't like the higher frequencies coming through the woofer, sure, you can lower the low pass filter to 70hz. However, if I was going to compete in SPL, I would wind my low pass filter all the way up and subsonic off

y would you do that...

what if u stuff up and play the wrong track which happens to be 35hz, which is way lower than your tuning frequency??

wouldnt it be better to bandpass it tghtly around the resonant freq???

may b e wrong here, honest question!!!

Well the way I see it, the slope of the low pass and subsonic may slightly attentuate your burping frequency. I don't want anything messing with the signal.

but one slope goes up, and the other goes down, they dont meet at anypoint do they???

if u have tuned to 60hz, and are obviously playing a 60hz tone,

and u set your subsonic to 55hz at 24db, and your low pass at 65hz at 24db, allowing room for crossover error and accuracy,

how would that effect the siganl at all???

I tend to agree with charger. Every comp i go in, subsonic filter is off and low pass is at about 200hz. Just for the slim chance it might be reducing my signal on the favoured note. Just be careful and only play the right notes.

So what is the right note then???

Maybe i'll try a sweep, and then try to guauge where the loudest was.....
I have another thread, and we are trying to figure out my post hole frequency, so i can get the amp tuned to that, and then play the right tune.

Would you turn bass boost off or on on the amp for the sub?

Well do it your way then and see how it works out

Well, i got 131.3

I played a sweep... 20 to 120....

Once i upgrade the Battery to a deep cycle, and upgrade my power cables and ground cables, i will easy get better.

My amp can't get the power it needs through my crappy 2 guage/4 guage cables.....

ive dfound in VTs, big power, big boxes yueilds good results

ive built a few vts

mine, 1200wrms, 2x 15"s 142.5
mates, 1x 15, 900wrms, 137.7
Anotha, 2x Fusion Powerplants, Sealed Boxes, 1200wrms, 140db

Trust us, for SPL, set your LPF to as high as it will possibly go.

If you set it to cut off anything above 50hz it is highly likely that you will miss your peak.

We accidently left the LPF on 1 of 4 D2s set to 50ish and it had a very noticable difference....not a good one either.

Thanks. Will do.

just noticed your bough cheetrs setup, mate purely show!!! thats it

see u got the sub in a smaller enclosure, just enough so to speak, then its not loading at all to the rear, which you need esp in a vt

now you have a sealed off false wall at the back there that allows no bass to enter cabin via parcel try holes or the ski hole

thats why dood!!!!! vts are restrictive enuff as it is for example

my mates VT with the 9515, has not in is parcel tray as in speakers etc and had the middle seat down adn the sub rear loading, got 136.6

then we undone the back seat, just the bits where ya back goes. and without even charging his (stock battery) back up, it done 137.8 straight up!

that gives ya an idea on how restrictive a vt is now, let alone with a wall blocking it all doo

Ooooooh i see......

Maybe i should get a couple of 15's and face them to the front then....
Lose the 6X9's in the shelf and maybe port the box through the shelf was an idea......

u could do that but ur custom boot install looks real good
up to u
unless ur gonna surprise us all with another crazy custom install

hehe...

I've never seen anything ported through the shelf before......

I wanna do it.....

Mmmmmm...... I have a few crazy ideas up my sleeve....

that would be pretty crazy
let us know what u end up doin
all d best

Im thinking twin ports, one for each sub.

Would it be best to do 2 seperate sub boxes or one single one?

2 sinlges would be easy for instalation.

I'll post up a pic of what i am designing tonight....