why is my system not loud enough?

Ok so i have a Pioneer DEH-12E head unit and a Power Acoustiks CPT1-4000D Mono block amp with two Pioneer TS-W253R 10 inch subs and one TS-W303R 12 inch sub hooked up to it. I have 6-gauge power and ground wire with 12-gauge speaker wire hooked up also. Now my question is when i hook up my 12 only my decibel meter reads 118, but when i hook up the two 10's (in parallel) the spl only goes up to 120.4.  Why is this? My amp is 1 ohm stable also. I just dont understand why when i add two more subs it barely changes the spl.

The Amp is rated 1200 watts rms @ 4Ohms 1700 @ 2 Ohms and 2200 @ 1 ohm

dBs are a logarithmic measurement as opposed to linear.  It takes significant increases in air movement to made dBs go up.  I believe the old rule of thumb is if you double your power and your cone space you will only gain 3dB.

That being said and incrase of 2.4dB sounds about right for what you added (if not a little on the high side).

Kevin Pierson

So what would be the best way to reach 140? Double my power?

Also i added a Alpine type R 12 and it went down to 119. I just cant understand why.  My setup is in the trunk of a 2006 Chevy cobalt with the back seats down and the subs are facing backward.  Ive seen one guy in a van that hit 140 with a single ten. Can someone explain this please??

Maybe you are choking your amp by making it try to supply all these subwoofers. Anyway, you split the output between the subs anyway.... try upgrading to a better quality wire....like a 4 guage or add another amp along with your other one.

To go from 120 to 140 you will need to increase 20 db which is roughly 7 3db segments.

That would be you would need to double your power 7 times (and double your subs 7 times).

So, if you added around 152,000 watts to your current setup (plus another 381 subs) you should be around 140db.  Now, remember, this is just a rule of thumb, but it should be fairly close.

Much much much more goes in to an SPL number then just the type of sub and the RMS power of the amp pushing it. 

What is your box tuned at?  Is it sealed or ported?  What kind of voltage are you seeing when the bass hits?  How much energy is lost in vibration of your Cobalt?  Those are a few starter points.  If you didn't custom build your box for maximum output based on the params of your particular subs you most likely won't see great SPL numbers out of it.  The box construction is just as important, if not more, then the equipment you are running.

Kevin Pierson

To go from 120 to 140 will be costly.  You may be better off getting a different vehicle.  What kind of vehicle do you have this equipment installed in?

WOw i didnt know so much went into it. I thought it was a little more simple then that lol. Well my cobalt rattles the trunk alot and no i dont have a custom built box but the boxs that they are in are the exact size for the subs. They are sealed also. I was hoping to start competeing but with a wife and being 19 and trying to get a house im gonna have to stick with what i got lol

120 dbSPL is MORE that sufficient for a daily driver.  In fact it will cause hearing loss if that level is sustained.  Unless you plan to go into competition it's not worth the money it would take to bump up 20db.  If what you want is to brag to your friends, do what I do:  lie.  Support the12volt.com

LOL! I had a customer said he was hitting 190. LOL. I said I wanted to see it because the current world record is 183. LOL.