Problem with new bass amp

[whocares2021]

So, I'm hoping you guys can help me out. I bought a used hartke vx3500, and I'm noticing that the low notes produce a deep rattling sound. It gets louder proportionate with the amp volume, and it only really noticeable when playing on my E and A strings. Any ideas what might be causing this, and how much it would cost to fix? I have no experience whatsoever with amp repair (never so much as opened one up) so please be as specific as possible.

 

[whocares2021]

Update: I unscrewed the front grill and I've narrowed the problem down to the bottom left speaker. When I play a note and put my finger against it the rattle is significantly reduced. I'd explore more, but I'm hesitant to take it apart further.

 

[RickenBoogie]

Even out your eq some, like start flat and only use small amounts of cut or boost. I suspect you're pushing too much low end, and your speakers, (what are those, btw?), aren't able to handle it.

 

[whocares2021]

Well, it's a combo unit so I would think that the speakers can handle whatever the EQ can put out. Even so, I tried completely turning off the EQ and turning low pass all the way down, and the rattle was still there in the bottom left speaker, although it was lessened. My completely uneducated opinion is that something inside is loose and rattling behind that speaker.

This is my exact unit btw:
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[Sneakypete]

This is what I'd do; Switch the amp off and pull the plug from the wall! Most speakers are fitted so that the outer flange where the fixing screws are located is on the outside of the baffle - this means removing drivers is easy. Carefully remove the screws that hold the speaker in place. Lift the speaker away from the baffle - there will probably only be a few inches of slack in the cable so have a couple of books or something similar to rest the speaker on. Rest the magnet on the books so that the speaker faces the ceiling. Can you see anything in the cab that might have been fouling the speaker cone? Sometimes it can be the wires to the speaker - use nylon cable ties to tidy up the wires so you know that when the speaker is refitted they won't touch. Spread your fingers over the cone and gently press downward - no more than 1/4" - does the cone move smoothly? Ease the pressure - does the cone return to its position smoothly? If you are nervous refit the speaker now but if you have commonsense (some bass-players do) switch on and try playing at very low volume - the sound will be thin but is the driver rattling? If you haven't found the cause by now try swapping the driver with one of the others. When the speakers are fitted properly try playing as before - is the same driver rattling in its new position? If so I think you need a new driver! Hope this helps.

 

[RickenBoogie]

Good advice above, but your assumption that a combo amp can handle ANY eq curve you set is incorrect. Careful and moderate use of an amps eq is essential, no matter if it's a combo or not. It's possible you've damaged the speaker from pumping too much low frequencies through it. Hopefully, it is just something loose inside, but just because the manufacturer put that speaker with that amp in that combo, is meaningless reguarding the use of both the eq AND the volume.

 

[whocares2021]

Thanks for the help. I opened everything up as per your instructions, and I discovered that it did not rattle when out of the cabinet. So I tightened all the screws up and the rattle seems to be gone. I'll have to turn it up tomorrow to be sure, since my neighbors would not appreciate a booming bass amp at 1 AM.

Oh, and thanks for the advice about the EQ. I probably wouldn't have tried too aggressive of a setting anyway, since I prefer my sound clear and smooth, but it's good to know I need to set limits.