Weird knocking sound - I'm a totally clueless

[edavis.j 10+ year member]

Okay so...

MMats 1600.2 Amp - 1150W RMS @ 2ohms

Fi Audio Q12 Sub - 1000W RMS - dual 1 ohm running @ 2 ohm

I am having a custom box built and meanwhile I was using this box I bought from a local car audio place. It worked fine for 2 weeks in a row, no problems at all. Randomly I'm driving and my bass just shuts off.

I check all my connections/fuses/etc. No problems at all. I redid ALL the wiring in my car, everywhere, made sure every single connection was good. Re did all the crimps and solder connection, and they are all now good connections. I fire up the sub and now it's making this weird knocking sound along with the bass. I took the subs out and did an ohm reading of the voice coils and the one was reading 1.4ohms and the other 1.3ohms, when I tested them in series, they were reading around 2-2.4ohms

That seems like it's in spec to me, but I'm clueless and probably did something dumb to **** this up. I mean it sounds horrible and I'm honestly really ****ing upset over this...

here's a youtube video of it I took earlier today to show exactly what I mean by the knocking sound..



Is the voice coil blown even though it's reading properly...? What exactly is that knocking sound? I also did the push on the center of the sub and if it's scratchy/rough then the coil is blown but it is fine...any help would be appreciated

thanks.

Click to read more...

 

[Nicktkd18]

Do you know if the sub has taken a beaten or been dropped recently. from youtube it sounds like your magnet is loose and hitting the structure. Also try pushing in the cone one the edges near the surround all around to see if its scrubbing just in a particular area and if you do your magnet may have shifted

 

[dumple 5,000+ posts]

recaros?? i like

 

[audioholic 5,000+ posts]

Could be a spider that came loose and is flappin. Definitely something moving that isn't suppose to be. Im betting it will be obvious when you remove it from the enclosure. But if not, take it out and free-air it.

I see a recone in your future.

 

[edavis.j 10+ year member]

Do you know if the sub has taken a beaten or been dropped recently. from youtube it sounds like your magnet is loose and hitting the structure. Also try pushing in the cone one the edges near the surround all around to see if its scrubbing just in a particular area and if you do your magnet may have shifted

The sub is only a month old and I haven't abused it all. Was handled very carefully, never slammed it around or just threw it around, and gain hasn't gone over 20%

recaros?? i like

haha thanks, but actually they're stock seats in gti's, i love them though, the plaid is different and they're comfortable as hell imo.

Could be a spider that came loose and is flappin. Definitely something moving that isn't suppose to be. Im betting it will be obvious when you remove it from the enclosure. But if not, take it out and free-air it.
I see a recone in your future.

Well I don't see anything physically wrong with it when I take it out of the box and look at it. But you're saying I should just hook it up and power it up out of the box and see if I can notice anything moving?

The subs only a month old so it's still under warranty...obviously this circumstance doesn't fall under manufactuer defects and would be classified as abuse and misuse probably, but would it be worth it to call them up and bs or no? And how much would it be to get something like this repaired?

 

[mclerico83 5,000+ posts]

usually like 100 bucks 2 recone id call up fi and have them repair it 4 u.

 

[Trey803 5,000+ posts]

FI sold me a defective q 10", kinda sounded like that but only on the very low notes. They quickly replaced it free of charge.

 

[edavis.j 10+ year member]

I'll have to try and call them later and see what they say...so what should I say is wrong with it? Just say a knocking noise

 

[SPLaudio 5,000+ posts]

loose dust cap or broken spider joint. play it free air( out of the box) dont send full power to it but get it moving...

 

[edavis.j 10+ year member]

also, random unrelated question:

how much voltage is needed to signal the remote turn on for the amp? my amp isn't turning on each time I power on...so I'm suspecting the remote turn on.

I measured the voltage with the car on and the amp wasn't turned on...and it was reading .3volts, is that enough to trigger it to turn on? also is there any gauge requirement for the remote turn on?

 

[mclerico83 5,000+ posts]

just some knocking noise and it needs 12v's to turn on just low amp like .1

 

[edavis.j 10+ year member]

Well I called Fi Audio, and the tech there told me he thinks that it's the terminal cup is shitty and it's causing an air leak...

Anyone shed some light on whether or not that sounds completely absurd or a possibility?

 

[Maxipads 10+ year member]

just take it out and free air.. if the noise is still there its your sub.. the first thing i thought it was was your prefab box was broken and the wood is slapping..

 

[mclerico83 5,000+ posts]

me 2 i thought it was the box shaking, i have heard shitty pre fabs make that noise before

 

[Maxipads 10+ year member]

my old prefab for under my seats make that exact noise.. the wood split where the top and left side med and slapped.