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Blown speaker or not????

Hey guys, I have a carvin bx500 powering a carvin RL810. 2 months ago I thought I blew a speaker. There wasn't any obvious damage but the sound it made was a horrendous, a loud buzz/growl and when I took it out and pressed on the cone, as it moved, it sounded like a dirty volume knob on an old stereo, so I replaced it. Last week, another speaker did the same thing. So just because, I put in the old one I thought was blown and it sounded perfect. No buzzing, growling or anything. Then about an hour in to practice, it started doing the same thing. Does this sound like I'm blowing speakers or is there another issue I'm not seeing. I do downtune to drop B (B F# B E), my tone is fairly bright and gritty (just using the drive control on the amp, no extra pedals) and never have the amp above 3-4.
 
Sounds like you're blowing cones to me, but really not sure without being there. One thing you can't rely on is numbers on knobs, though. Some amps give up most of their clean potential right around that point. Don't know about yours, but it's possible you're cranking too loud for the cab. Doesn't sound unreasonable on paper what you're doing, but I don't know enough about your situation.
 
I'd be shocked if it's too loud for the cab. The head is rated at 500w at 4ohms and the cab is rated at 1000w at 4ohms. I've pushed it harder before with a carvin r600 head years ago before I played gigs that didn't mic everything. What is surprising to me is that there is no visible damage to anything on the speakers and that the original "blown" one worked perfectly tonight for about an hour.
 
Based on what you describe, the voice coil has what's called a rub - which is caused by the woofer being overdriven. The wire in the voice coil, or the adhesive holding it together got too hot and / or was driven past its excursion capability.

This isn't about how much power the speaker can handle, it's about how much distortion the amplifier was generating and if the amp could control the movement of the cone. It's also possible that the woofer has a manufacturing defect which is easily detected by looking at the voice coil to see if the wires are burnt.
 
Thank you guys for replying!

Let get this straight you have an 8x10? With eight woofers how are you sure that you have found the offending one?
Its very easy to tell which speaker is the issue. You put your ear up to each speaker and listen. And you can see the excursion on the bad one is twice that of all the others.

Are you positive it is a problem with the woofer and not an electrical problem?
It might be an electrical issue but I have no idea why and what would be causing it

Check the baffle board where that speaker mounts for flatness. Could be warped distorting the speaker basket.
To my eye, everything looks fine

Based on what you describe, the voice coil has what's called a rub - which is caused by the woofer being overdriven. The wire in the voice coil, or the adhesive holding it together got too hot and / or was driven past its excursion capability.

This isn't about how much power the speaker can handle, it's about how much distortion the amplifier was generating and if the amp could control the movement of the cone. It's also possible that the woofer has a manufacturing defect which is easily detected by looking at the voice coil to see if the wires are burnt.
It certainly sounds like something is rubbing when I push on the cone but it's almost like you can keep pushing until it goes away, just like turning a dirty knob until the fuzz goes away. I can't imagine its a manufacturer defect, the cab is over 10 years old and I am just now having issues with it. Again, everything looks fine to the eye, no holes, no burns, no loose wires, as far as I can see (and I'm no pro) everything LOOKS fine. Is there anyway to test to see if there is a rub anywhere? is that something that I would be able to see? I'm trying to figure out everything before I go and spend another $50 on a speaker if it's not the real issue.
 
If the hardware that attaches the speaker to the baffle is overtightened in an uneven way around the frame, the speaker frame can warp which can cause this problem. More than likely you are blowing your speakers. If it isn't doing it when the speaker is cold but it is when it is hot, it could be that the metal coil is expanding and rubbing. Check the speaker cone movement while you are playing and see if there is too much excursion (moving in and out ) so that it is bottoming out. It could be that you are driving them too hard. Cutting the bass tone control can help.
 
Probably has nothing to do with your problem, but still something to be aware of:.
That was more in reference to what Gizmot said about a possible manufacture defect. I don't think it would take 10+ years of playing and abuse for a defect to show up.

If the hardware that attaches the speaker to the baffle is overtightened in an uneven way around the frame, the speaker frame can warp which can cause this problem. More than likely you are blowing your speakers. If it isn't doing it when the speaker is cold but it is when it is hot, it could be that the metal coil is expanding and rubbing. Check the speaker cone movement while you are playing and see if there is too much excursion (moving in and out ) so that it is bottoming out. It could be that you are driving them too hard. Cutting the bass tone control can help.

I was careful to make sure they are all tightened evenly enough that it should be fine. The excursion is obviously more than any other speaker, so I know there is something up simply by that. My bass is set at -3 and the eq favors the high end, so I my settings are fine, I ran lower settings with my R600 so I don't think that is the issue here.

If you feel anything other than free movement when you manually test the excursion - any catch, noise, rub or bind - the driver is shot and needs replaced or re-coned. It's really as simple as that.

That's what I figured and what made most sense to me. I just wanted to see if there was anything that I might be missing. I'm guessing that since it's 10+ year old and has seen many many shows and many many many hours of play and lots of abuse (I got it when I was 15 and didn't think to be easier on it) has just taken it's tole on the drivers, and they are finally starting to go out. At $50 a piece, its still more affordable to buy a driver as it goes out than it is to buy a new cab.
 
I've heard that HPF devices like the micro thumpinator are really not all that useful for bass-specific amps like the BX500, because they typically already have some amount of protection for ultra-low frequency spikes built-in. Is that nonsense?
 

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