Cerwin Vega sub 100 makes a crackle sound

[Knucklehead545]

I made a subwoofer cable for 30 feet and I bought a cerwin Vega sub 100 for 35$ and it now makes a crackle whenever it is turned up loud

 

[Mr Kagouris]

Could be EMI considering the long cable. How well insulated is the cable?

 

[americanaudiophile]

If the crackling happens only at loud volumes you could be playing it louder than it can play, boosting the bass more than it can handle, or it could be a bad woofer or amp since you got it used.
Does the cracking happen when you connect it with short cable? Does it happen if the sub is plugged into a different AC outlet?

 

[Knucklehead545]

I think its the amp plate, we tried different cables no diffrence

 

[soundguruman]

Open the speaker cabinet
Remove the speaker
With your fingers, move the speaker cone in and out, like a piston.

DOES the speaker make a scraping noise, when you move the cone in/out?
If so, the speaker is blown.

The speaker cone must be FREE to move in / out without interference (scraping) against the magnet.

This is a very common problem: speaker blown.

You can replace the speaker, or have it RE-coned.

No, it has nothing to do w/ speaker cable or EMI, etc...It's a mechanical problem...voice coil is scraping against the magnet.

 

[jdlech]

More specifically, a speaker coil becomes permanently warped due to high temperatures. Once that happens, the coil rubs against the magnet. There is no reliable way to un-warp a coil.
Other problems includes a torn spider (the part behind the speaker cone that prevents it from moving too far). Also, weakened foam surround will allow it to move too easily. This is often the case when a speaker is improperly stored for a long period of time. Downward firing subs are especially bad for this. Drivers are to be stored either vertically, or in a container that holds the cone in it's centered position.

 

[soundguruman]

Yeah, on Cerwin Vega:
the foam surround on the speaker could be rotted away.
Take out the speaker and check the foam.