HI all I have a problem with one of my drivers. Around 300-450 hz the LF driver in one of my Community MVP 15 cabs makes weird noises as if the cone is damaged, only it looks fine.I have an email in to the UK suppliers but I think parts are going to be a no go. The replacement driver is ,I think, £120 plus. So questions are:
1. What tests can I do to check / what could be making the noise ?
2. Any ideas for another drop in driver which is better / cheaper?
Thanks in advance for your knowledge
1. What tests can I do to check / what could be making the noise ?
2. Any ideas for another drop in driver which is better / cheaper?
Thanks in advance for your knowledge
Some photos might be useful - pull the defective driver and lets see what we can see. Run a frequency sweep through. If you find the right frequency, listen to different parts of the driver and figure where its coming from. Don't discount that the cabinet might be at fault. To check, swap the drivers over when you replace them, and see if the problem follows the driver or the cabinet.
IMHO, the speakers don't look great: the frequency response is all over the show, and the compression driver (3/4" exit) is a bit undersized for the purpose.
If you want to replace a driver, you're better off replacing in pairs if you're dropping a different driver in there, or you'll get a weird stereo image. Not a big problem for vocal reinforcement and the like, but "serious" gigs should definitely have matching sides.
Something different that'd do the job would be something like an Eminence Beta 15.
PM me if you're nearby - its easier to go over these things in person.
Chris
IMHO, the speakers don't look great: the frequency response is all over the show, and the compression driver (3/4" exit) is a bit undersized for the purpose.
If you want to replace a driver, you're better off replacing in pairs if you're dropping a different driver in there, or you'll get a weird stereo image. Not a big problem for vocal reinforcement and the like, but "serious" gigs should definitely have matching sides.
Something different that'd do the job would be something like an Eminence Beta 15.
PM me if you're nearby - its easier to go over these things in person.
Chris
Several possibilities here, pull the driver and do a test sweep on it outside the cabinet just to make sure it's the driver and not something in the cab making the noise. If the driver is confirmed then inspect it for tinsel leads slapping on the cone, suspension that has come unglued from the frame, or something similar with the dust cap.
If you're powering the cabs off each side of a stereo power amp, swap the connectors & see if the problem follows the driver or the channel. I'd check the cables, power, & processing gear 1st before assuming that the problem is the driver itself.
Forgot to add that the spec sheet mentions a "Mid-Range Boost" switch, tho it doesn't specify whether it's lower (woofer) or upper (tweeter) midrange. Probably upper, for more vocal clarity. We might take a peek at that, anyway.
Thanks for the replies I'm looking after my son today so no play time for me. Mrs hips is not working tomorrow so I might get some stuff done,I will report my findings.
Chris thanks for the offer of eyes on but I'm in between Birmingham and Worcester so I guess a couple of hours from you. In all honesty the cabs are not great but then neither is any other of my gear and then don't earn they just mean I don't have to pay anyone else with equally poor sounding stuff to have noise at social engagements which I attended/put on. I bought them new with a group of friends for an annual fancy dress party we used to put on. End history .
OK , up dates: I tested speaker again with different set up, different cables and amp/mixer, same results . Removed driver to confirm it's not the cab, same noise using both the crossover with extended leads and raw driver. Same noise. It only happens at high power levels so testing was limited due to annoyed wife. However I did surgery on the dust cap anyway as I couldn't see / feel any loose suspension. Same for the dust cap, that was still solidly glued on. Tinsel leads not causing noise. It sounded as though it was something under the dust cap vibrating hence the removal. Nothing loose ,but .. when I press the cone down or pull it up towards travel limit I get a rubbing noise no matter how careful I am with keeping the pressure equal. I tried the same thing on a 12" I had spare and the noise only happens on that driver when pressure is unequal i.e cone not traveling straight. I took a couple of snaps but not sure they will help so won't post them for now. As I'm pretty sure that rubbing noise is what I'm hearing I guess I'm now looking for recommendations for replacement drivers.
Now we know 2 things: The rest of your gear checks out, and you have a barbequed voice coil. I suggest that you replace both 15s so they sound alike, plus you avoid the 2nd 15 rudely failing during performance.
The "Press Test". Carefully place your fingers near & around the dust cap, then press down as evenly as possible. If you hear a scratchy and/or rubbing sound, then the voice coil likely has been burned & distorted due to overheating. The only other condition might be the presence of a foreign object lodged in the VC gap. (If the magnet is removable, you might take a peek with a flashlight.) If the box's damping material is dusty old fiberglass, sometimes the dust can migrate into the VC as well, which is why some manufacturers have switched to polyester fiberfill. Given the power handling of the woofer, I'm guessing it's a burned VC.
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