Bass Driver Not Working Properly

[spinner 0]

I had a spare new Eminence Kilomax bass driver which i was unlikely to use so I sold it on Ebay.

 

Before advertising it I checked the impedance with a multimeter and hooked it up to a small amp to check it was working OK. It was.

 

I sent it by courier in its original box.

 

The buyer has told me that at low volumes it's fine but when cranked up it makes a rattling noise louder than the the music.

 

In addition the foam has come away from the frame at one point. Bearing that in mind it's possible that it was damaged in transit.

 

But what would cause the rattling at higher volumes. Could it be a damaged voice coil?

 

Any ideas please?

Edited March 6, 2009 by spinner

[Raymilkybarkid 0]

could be a damaged voice coil, try gluing the foam back into place it is possible that this is the rattle when the cone resinates

[spinner 0]

could be a damaged voice coil, try gluing the foam back into place it is possible that this is the rattle when the cone resinates

 

 

Aren't these two different things though?

 

The foam is on the frame/surround. What effect would that have on the voice coil?

[norty303 0]

Rattles are normally caused by a loose dustcap, loose spider or surround or its the voice coil hitting the backplate due to overexcursion. If the person is using the driver in free air at high volumes its because its not loaded properly (in a cab by an air mass as it was designed to be) and the person is a numpty....

[Kingy 0]

I agree with Norty,the first thing I would suspect is the dust cover. Failing that if the spider is distorted somehow this may cause the same problem.

[norty303 0]

Actually, to expand on the over excursion thing, the Kilomax is a notoriously difficult driver to load right. In simulations for reflex cabs it runs out of excursion long before it gets anywhere near its quoted max power rating (1000w or 1200w iirc which is why people tend to buy them because they just see massive power figures). Even fiddling with port tunings and cab volumes tends to not give very satisfying results.

 

If he is indeed driving it with moderate power in free air then I'd be inclined to go with this reason if the dustcap and surround look good.

 

Check these links for some discussion about kilomax drivers

 

http://www.speakerplans.com/forum/forum_po...D=171535#171535

 

http://www.speakerplans.com/forum/forum_po...D=160967#160967

Edited March 6, 2009 by norty303

[spinner 0]

Rattles are normally caused by a loose dustcap, loose spider or surround or its the voice coil hitting the backplate due to overexcursion. If the person is using the driver in free air at high volumes its because its not loaded properly (in a cab by an air mass as it was designed to be) and the person is a numpty....

 

 

Oh oh. I think he may have been using it in free air. Does this mean he may have damaged it?

 

But what would cause a loose dustcap or spider, could either have happened in transit and can either be rectified easily to get back to normal performance?

 

Thanks both for the advice.

Edited March 6, 2009 by spinner

[norty303 0]

Oh oh. I think he may have been using it in free air. Does this mean he may have damaged it?

 

But what would cause a loose dustcap or spider, could either have happened in transit and can either be rectified easily to get back to normal performance?

 

Thanks both for the advice.

 

Smacking the voice coil former against the back plate won't do it any good, however if it isn't for extended periods you usually get away with it.

 

An easy way to test for loose dustcaps is to tap the cone. It should sound dead, with a bit of resonance. You can hear the difference if the dustcap is loose. I've just had one of my reconed drivers suffer a loose dustcap and from inspection it looked ok. It was only once i cut the dustcap off that i could tell it had been vibrating as the sound went away. Easily reglued with a bit of Evostick impact adhesive or similar.

 

However, you do say that the rattle was louder than the music which does suggest it banging the backplate

 

[Bouncy Dancefloor 0]

everyone has posted very helpful technical advice

 

ill put my 2p in, just to be careful

 

I have sold thousands of items on ebay, Drivers and s/h drivers are no-go areas. Why is he buying a replacement driver? Because hes blown his existing one up! So how easy is it for him to buy a replacement on ebay, through paypal and just swap them (and file a complaint, so paypal will refund him) and complain that the driver is faulty or damaged in transit

 

Had someone do this with Bose 802 Drivers, he sent them back to us, All of them destroyed, with rips and many of the magnets were seized too (through heat). We knew what he had done, but what could we do? We couldnt prove anything

[superstardeejay 0]

Similar experience here. We sent a reconditioned, perfect Vestax mixer to a buyer in Ireland and he sent lots of emails saying how badly it sounded and distorted and how the faders were all worn out (strange as we'd fitted all brand new ones). He was threatening to destroy our 100% good feedback unless we gave him a refund. I replied he didnt need to threaten us, we'd gladly refund his money on receipt of the mixer, but if the mixer turned out not to be faulty then we would leave the carriage charge in place. He emailed us a week later and said that he'd been connecting his CD player to the Phono inputs because his mate had told him that was the correct way to do it, and when he'd moved them to the line inputs it had all gone right on its own!

 

:blameless:

 

 

[gadget 0]

everyone has posted very helpful technical advice

 

ill put my 2p in, just to be careful

 

I have sold thousands of items on ebay, Drivers and s/h drivers are no-go areas. Why is he buying a replacement driver? Because hes blown his existing one up! So how easy is it for him to buy a replacement on ebay, through paypal and just swap them (and file a complaint, so paypal will refund him) and complain that the driver is faulty or damaged in transit

 

Had someone do this with Bose 802 Drivers, he sent them back to us, All of them destroyed, with rips and many of the magnets were seized too (through heat). We knew what he had done, but what could we do? We couldnt prove anything

 

 

Don't drivers have serial numbers on at all? Perhaps one thing you could do is somehow security mark them (UV Pen?) that way you could prove they're not the ones you sent them.

 

I agree PayPal sucks for such things though, buyers doing the dirty is really annoying...

 

 

David