I have a JVC headunit set at max gain and an Alpine MRP450 mono amp gain maxed. I have freq cut off set low like 100 htz and no bass boost.

The amp is rated 450 @ 2ohm and subs are 250 rms. So each sub should be getting 225 rms. They are Rockford Fosgate p2 R2D2 2ohm DVC. One coil goes to amp and other coil the positive goes to negative. This should be a 2 ohm load.

Is this correct?

Do I need a bigger amp?

Maybe bad ground?

Will it hurt subs if I get a 1ohm amp?

Maybe the ****ty aluminum 4 ga wire with several splices?

 

 

I noticed I Have mine wired right from coil to amp on both speakers, not coil to other coil then only one set of wires going back. Maybe this makes a difference?

 

Looks like this more so...

 

I also have power and RCA on same side.... Dont think I'd lose power from that. Just had distortion.

 

Sounds crazy but when I had stock HU the gain wasn't set as high. Think I'm going to try the line level inputs and ditch the low level RCAs. Maybe the RCA preamp voltage is too low. Last time I needed a line level harness for an install I hacked up a blown computer power supply for the harness FYI.

What's funny is if I didn't have this conversation with myself I wouldn't have thought of this. I guess I needed expert advice. Haha

I'll report back with my findings.

 

i ended up adding the EQ instead of running speaker wire, its louder- but could still hit harder. i have the EQ maxed out too.

its nice being able to change the Sub gain and crossover on the fly. its red or green illimination so it mactches nice

Under further investigation, other people have had the same problem with this Headunit.
http://www.crutchfield.com/S-ef42fzU...KW-R800BT.html
JVC/Kendwood ADMITS there is a flaw. i even updated the firmware.
When i turn the rear PREAMPs to SUBWOOFER OUT, it opens up the HPF option, when activated it shuts off the the subs. So basically the high pass filter is useless.

i am confident if i ran line level inputs, it would be louder. i dont have or want to run all the wire and i dont have the plug.

 

@caraudio.com

"Re: Head Unit HPF cutting signal to subwoofer?
I know I'm chiming in a bit late on this, but I'm experiencing the exact same issue with my JVC KW-R500. As with the OP, I'm positive that the RCA's are connected to the rear/sub output. I turn on the high pass filter and my subs stop working (well, they stop putting out sound). I was "relieved" to see someone else with a JVC HU is having the problem. That means I'm not going nuts.

Anyhow, if the OP sees this, I'm curious as to how your situation turned out?

Obviously JVC is having this issue on more than one model. Not good. I'll be replacing this mediocre HU relatively soonish for a different brand but I'm curious about what JVC told you if you contacted them. (My HU also seems to have weak RCA voltage, but that's a whole other topic.) "

 

 

You need to get a volt meter and see what your output voltage is and the set the gain on the amp to match it. The input sensitivity is not a volume adjustment. It is there to match rca live voltage of your head unit. You can also look for a line driver if the voltage of your rca's is very low. Keep in mind your amp's max input voltage and do not go over that or you can smoke the input circuit and have a dead amp. If it were my set up I would think a bigger amp is needed. If you are running two subs the add the rms of both and get a amp that has a minimum of that. A little more is okay and won't hurt anything. Is your box ported or sealed? If its sealed you can give in more rms power to overcome the mechanical vaccum of the box. Remember that a seal box needs more power to make the same volume of a ported box. almost 3db's which is actually alot.

 

You need extra battery power to keep your voltage strong. As close to your amplifier(s) as possible.