GK MB210 problem

[Infidelity]

I got this MB210 used from our fellow TB'er..

The problem is at lower levels, everything set flat, limiter on, boost and horn turned off(master at 9:00) the combo runs fine..

When I turn the master higher than 9:00 it goes crazy.. When I hit the harmonics on 7th fret on G and 5th fret on D the amp will start to rattle. The whole G string is rattling fest too!

I tightened everything, checked the wires if they're blocking the speaker ports, and tried another amp if it was the bass(it wasn't. I even tried a really high action on the bass). The problem still persists..

It seems like the lower driver is the cause of the rattle.. I tested it by touching the cones lightly when the rattling is going and when I touch the lower driver it lessens the rattle.

Is it possible that the lower driver is bad but not blown?

[B-string]

Yes could be shipping damage.

[Infidelity]

Originally Posted by B-string

Yes could be shipping damage.

Hmmm.. That could be the culprit..

[5port]

Remove lower speaker and check to make sure the speaker wire is not laying up against the speaker cone. Reposition the wire away from speaker.

[Infidelity]

Originally Posted by 5port

Remove lower speaker and check to make sure the speaker wire is not laying up against the speaker cone. Reposition the wire away from speaker.

Very unlikely tried that 3x..

[jelwood]

Put cabinet on soft furniture (a couch?). Remove suspected culprit from cabinet via unscrewing. Lay the speaker on the couch, cone facing skywards. Now play through the combo. If the rattling is intrinsic to the speaker you will still hear the rattle, if not it's something about the way the speaker and the cab interact. All I can say.

[audiomitch]

Check the little round screen over the piezo horn. If it's missing, check to see if it's stuck to the magnet on the back of the speakers. Sometimes it comes off and falls through the port. Also might try removing the Piezo altogether. If it cures the problem, you'll know you have a blown horn.

I had similar problems and they were all related to the little Piezo horn.

Good luck!

[Infidelity]

Originally Posted by jelwood

Put cabinet on soft furniture (a couch?). Remove suspected culprit from cabinet via unscrewing. Lay the speaker on the couch, cone facing skywards. Now play through the combo. If the rattling is intrinsic to the speaker you will still hear the rattle, if not it's something about the way the speaker and the cab interact. All I can say.

It still happens.. So it could really be the driver.

Originally Posted by audiomitch

Check the little round screen over the piezo horn. If it's missing, check to see if it's stuck to the magnet on the back of the speakers. Sometimes it comes off and falls through the port. Also might try removing the Piezo altogether. If it cures the problem, you'll know you have a blown horn.

I had similar problems and they were all related to the little Piezo horn.

Good luck!

Everything is intact..