Does this sound correct

MikoJL Newbie
Jun 29, 2019
Hello all. New to the forum here.

Sorry if this is a stupid request and If i describe anything incorrectly go easy on me. lol

I recently replaced my old Subwoofer with a new JL 13w7. 

Please enlighten me if my settings are set correctly or if anything needs to be fixed. 


Subwoofer- JL 13w7  1.5 - 3ohm Sub

JL Website states 1,000 Watt RMS. Sonic states 1,000 to 1,200 Watts RMS.

Subwoofer is Wired in Series for 3 ohm. 

Amp is a Rockford Fosgate T1500 -1bdCP   4-2-1ohm

Tuned using a 30hz test tone with multi-meter. I have my voltage set at 55 which at 3 ohms = 1,008 Watts according to ohms law- Source 

For fun I played a 50hz test tone and my meter read 62 volts equaling 1,281 Watts. 

Stock head unit. 2019 Jeep Cherokee. Volume at 25 for test. No clipping and no distortion.

I also have a worthless Punch EQ that I cant use if all the settings are done at the amp but

Max RMS is 1,500 - 67.08 V so I might be able to move it up a hair once in a blue moon to get a little more if need be.

Made a custom box with JL Specs. 

Thanks in advance for any help or suggestions. 

Attached some pics to show what the build looks like.



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Acoustics Engineer
Premium Member
10+ year member
May 1, 2007
Quad Cities, IL
Nice equipment. 

When using a DMM, using a 50Hz tone is more accurate as most meters are calibrated for 50Hz-60Hz (typical AC voltages).   Verify if 30Hz is out of the range of the meter, or maybe the head unit has a lower output at 30Hz. 

Note that any EQ boost will invalidate your gain process.

Amp mounting tips: don't mount the amp on the box because 1. vibration takes its toll on the amp, 2. it makes it easier to steal the entire package, 2. the amp is visible increasing possible theft, and 4. if the box moves the amp wires are less flexible and can pull out.  I assume you've securely bolted the box to the floor. 


MikoJL Newbie
Jun 29, 2019
Thank you for the response. The box is bolted down with 2 L Brackets in the back. Keeps it perfectly centered and wont budge. I'll def have to move the amp somewhere else then. I did not think of how the vibration would effect it. Thanks for the tip.  I know about the EQ Boost. I bought it because someone told me it was a good idea and I haven't even messed with it at all so it was pretty much a waste unless I adjust the EQ Knob to max and set my gain but I dont know if thats a good idea or not. When I was setting the hz I tested that theory at EQ knob all the way down was about 22v leaving the sub under powered at that point. I've never used an EQ Boost so i'm better off not using it until I know how.

View attachment Blue-Point MTIND683A Instruction Manual (Page 5 of 12).html


MikoJL Newbie
Jun 29, 2019
Ok So I attempted to mount the amp to the back of the seat. The angle of the seat forces the bottom of the amp to sit onto the carpet as well as closing in the area which would allow no air flow so I decided not to mount it there. I ended up just remounting the Box over to the side and mounting the amp to the floor instead. It doesn't look the best but it wont be on the Box and maybe the air flow from the Subwoofer Port will help keep the amp cool. The ground wire just barely reached with maybe 2 inches of slack. 



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