sub started making weird sound

[ShadeTreeMechanic]

What size is your box? Your coils are 4 ohms all in parallel for a 1 ohm load correct?

[eyeopeningepisode]

Rewired everything and all seems good. My ground was a bit shitty but i redid with a better point..scraped cleanly..no paint. Used a lock washer and self bolting. Looks good and no hot points whatsoever. The subs did that burp one time only while playing at a pretty high volume and for a while. I reset all my amps settings and need to know how to set the gain first and then the lpf and subsonic i know how. I tried ohms law method for gain. Turned down all eq settings...gain down...lpf up all the way....ssf down all the way. 2000 watts rms x1ohm...is 2000...square root is 44.72 or 45. I played a 50 hz test tone at 75% of my hu volume and i hardly had to move the gain before i was at 45 volts. Then i played a 80hzt test unit at 25% of my hu volume and it was at 10.1...volume also at 10 volts. 10.1 x .707...something didnt seem right here.

[eyeopeningepisode]

What size is your box? Your coils are 4 ohms all in parallel for a 1 ohm load correct?

Not sure...it was custom built to give each sub 1.25 cu ft. 35hz tuned slotted port.

[Kyblack76]

Good hell.

Pull the driver and free air it. Also feel the coil. Push up and down on it and listen.

Your amp protecting, may show a bubbled coil. And at certain throw, it will protect the amp.

Pull the driver. Feel, look, listen.

[ShadeTreeMechanic]

Also check the spiders and tinsel leads while you are at it.

When you set your gain at a certain head unit volume, that level becomes your reference. Music is recorded at different levels and different sources can be different too. It is quite possible to overdrive your system even with the head unit at its magic number.

[eyeopeningepisode]

Update: I think my head unit may be too cheap for my setup, here's why.

I got the SMD DD-1 and I set the eq's on my Head unit to flat. My HU is the DUAL DV625BH. I chose this model because it has 2 video outputs for 2 headrest dvd players. This way if I play something on the HU, it could be displayed to the headrest dvd's. It's pretty slick and I didn't know if other units did this...had 2 video outputs.

Also, the rca's front/rear/sub are all 4 volt. This unit is also supposed to be CEA-2006 Compliant..so for $189...I thought it's a steal, even if the interface isn't as nice as more expensive head units.

Well, attached the dd-1 to the units rca. I have a clarion xc1410 amp that gives my door speakers 50watts rms x 4. (BTW, This sucker is CEA-Compliant too and it really does more than 50 watts, I've busted 55watts rms kickers and right now I have the 75watt ones and they are taking a beating with this amp too. HPF set at 90.)

I took one of the rcas coming to the clarion xc1410 and played the 1khz track on the cd and fired up the dd-1. I got up to volume 31,32 of 40 before the distortion light came on. I then proceeded to do the same for the subwoofer rca. I took the rca coming from the hu's rca into my monoblock and connected it directly to the dd-1. I played the track with 40hz db-0....and got to volume 24 tops before it distorted...then went down to 23 and it went away. volume 23 of 40 for the subwoofer output does not seem too good to me. Is my headunit to crappy for running my setup? I didn't even bother using the leads on the dd-1 into the amps speaker terminals to adjust the gain at this point. I figured something must be wrong. Most video's I've seen using the dd-1 get up to like volume, 38, 37 of 40.

Any feedback is appreciated.

other info: running a diesel truck, 2 batteries, no big 3, 2 gauge wire for power and ground, very little dimming of lights parked....hardly noticeable driving.

[reedal]

Nothing wrong, that's just where your HU distorts at 40hz. Did you ensure all filters and EQ's on the HU were turned off or set to flat?You can use that HU still if you want, or you can research for one that does the same things. If you want a new one, I'd recommend pioneer or kenwood.

You have an amp for your subs and an amp for your mids and highs correct? So, the only difference between being able to turn your HU up to 40 cleanly (others as you stated) vs YOU only being able to turn it up to 23 cleanly, is that it won't take as long for your speakers to get louder when you turn the volume up to your maximum clean. I say if you're happy with that HU, keep it, get that DD-1 ready again, and set your amps to their max clean with your HU volume set to 23 (no more than -5dB for mids/highs amp, no more than -10dB for sub amp). It doesn't matter if your volume distorts at 23 or 40, because if your amps are set to max clean at volume 40, that's all the amp can put out. If it's max clean with volume at 23, then it's the exact same power as the other, except the gain had to be turned a little higher to reach max clean.