Hi guys, I have a Ground Zero Hydrogen 15. DVC 1000 RMS. I hooked it up to my 'kick-ass' (now sold) [img]graemlins/puke.gif[/img] Ultra-linear amp. That amp suspossed to put of 1000 RMS @2ohms. (what a sad-joke really) [img]graemlins/banghead.gif[/img] It was sure louder then my 100 watt Panasonic amp, but after a while, the sub developed a loud scratching sound, I know the VC is scraping againest the pole piece, its really bad, unless its in a box, just pounding so that bass overpowers the scratching sound. WIll this sound eventually go away: if I hook it up to a stereo reciever, and just let it play bass CD's at low levels, for a few days? or is it permanantly screwed? [img]graemlins/banghead.gif[/img]

I'm thinking that if your sub makes like a scratching noise that the VC might be scraping on the walls of the well it sits in.

Is it possible that your spider or surround is not secured properly so the VC is centered? I would try moving the sub up and down applying pressure to different edges of the diaphram to see if the VC scratches in one place in particular.

Also, check the resistance of the two VCs to see they match up properly.

If your VC wire is slightly damaged it may make a scratching noise but that usually doesn't fix itself...

This could be a testimate to ultra linear amps -destroying that great big sub [img]tongue.gif[/img]

(that amp will definatly do about 850RMS @ 12v, though)

It almost sounds like you said you were powering this sub without it being in a box ?

That could account for a bent coil former, from bottoming out...

I know the coil former must be bent from the VC bottoming out from it hitting againest the pole piece. Whats worse, I also fried my Kove Armaggedon M15, thats an $800 sub. I just about played whack-a-mole with that amp using a sledge-hammer, wow was I upset, it now sits at Cash-converters Macleod for $279.99 if fool is interested. But thats $200.00 more then its worth.
thanks Fabe for the help, I'll do that

It would have got bent from hitting the back plate or on the way back into the gap after leaving it...

If part of the suspension let go- then it could have got bent inside the gap/pole....

(more then likly it was bottomed out, though)

Either way, your subs were damaged from overexcursion/abuse - not the amplifier...

Haunz, you dont know as much about this stuff as you'd like to think you do. If you know about power signal damping, and control of the subwoofer cone in relation to the signal produced by the amp, you'd know that it IS in fact the amp. The box was designed for the sub NOT to be over-excursioned. But the amp crapped out and sent a constant DC signal to the sub when it should'nt have (it clipped), that's' why it bottomed out, and hit the pole piece, honestly buddy, if you dont knwo what your talking about, dont talk, thanks.