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Speaker problem, or not?

A

AfroMan Skeeter

Dec 12, 2007
125
0
#1
I have no idea if I am doing damage to my speaker because there's 3 possibilities that could be happening.

1. Clipping (un-likely)
2. Speaker bottoming out and voice coil hitting the back plate
3. Speaker is hitting the grill

How do I tell for sure what is happening here? I know the speaker shouldn't hit the grill, but I got this cabinet off of a guy and he had replaced the 15" speaker in the SWR cab with a better one.. maybe it has a bigger Xmax and is hitting it?

The sound is a quick click if I give the E string a good thump, I didn't dare try holding down a low note with the chance of damaging my poor speaker :[
 
#2
My guess is you're hearing the voice coil former tap the backplate. I don't think paper-on-grille would produce a click, and chances are the excursion it would take to tap the grille is greater than the excursion it would take to tap the backplate.
 
#3
If I am reading you right, you hear the noise when you touch the strings a bit percussively? I'm suspecting your rig is reproducing a bit too much subsonic. If you can remove the speaker grill and observe what's happening, it should give you a clue. If the speaker cones jump noticeably when you touch the strings hard, that's your issue. Solution is to add a 30-35Hz high pass filter to your amp setup. There's also the possibility that the previous owner installed a speaker w/too little xmax, and/or didn't match the driver too well w/the cab. Pull it out and see what you have. Not too difficult to find a data sheet. For our purposes xmax should be at least 4.5mm. Less than that and its possible you might have some issues.
 
#5
dhomer said:
If I am reading you right, you hear the noise when you touch the strings a bit percussively? I'm suspecting your rig is reproducing a bit too much subsonic. If you can remove the speaker grill and observe what's happening, it should give you a clue. If the speaker cones jump noticeably when you touch the strings hard, that's your issue. Solution is to add a 30-35Hz high pass filter to your amp setup. There's also the possibility that the previous owner installed a speaker w/too little xmax, and/or didn't match the driver too well w/the cab. Pull it out and see what you have. Not too difficult to find a data sheet. For our purposes xmax should be at least 4.5mm. Less than that and its possible you might have some issues.
Click to expand...

Thank you, I should be getting the spec sheet soon. Like I said to the other person, I learned my lesson from getting this cabinet.
 
#6
dhomer said:
For our purposes xmax should be at least 4.5mm. Less than that and its possible you might have some issues.
Click to expand...
Definitely for HIS purposes ;) But there's more to it than just xmax. There's also the tuning of the cab to consider, and if it's off for that speaker, it can bottom out way sooner than if it was in a cab designed for it. And there's also the possibility that he's just way too freakin' loud for any 115.
 
#7
I guess I'll be ok with it if the problem doesn't occur with my 212 and 115. Since 450 watts are going into this as a stand alone cab.

Using them together each will get about 312.5 watts and that might help.. otherwise it's back to saving!
 
#8
The over-excursion could be happening because the cab is tuned too high, or too low, or the woofer just plain doesn't have enough x-max no matter how you tune it.

My guess would be that the tuning is too high.

AfroMan Skeeter, if you're up for an experiment, you might try this: Assuming the cab has a slot port, try inserting a board or two into the port sufficient to reduce the port's area by about about 20%. The board should go as deep as the port goes; a little longer than the port is better than a little shorter. This will reduce the tuning frequency by ballpark 10% or so, hopefully resulting in less cone motion in the region of the fundamental (assuming it's a powerful fundamental that's causing the bottoming out). Then try thumping the E-string, gently at first, building up gradually, to see if the problem has gotten worse or gotten better. If it's worse, then we moved the tuning in the wrong direction. If better, we moved it in the right direction, but we don't know if we moved it too much or too little or just right (unlikely). If there's no change, then we're barking up the wrong tree.
 
#10
billfitzmaurice said:
By whose definition? Without knowing what the driver is no one can draw a valid conclusion.
Click to expand...

I'm sorry about that, it's an Eminence Kappa that's rated at 450 watts (4 Ohm). I don't know the exact driver myself, I pulled it out and it didn't say anything but EMINENCE Kappa.

I did remove the grill to test it, and walla problem solved. I guess it really is the simplest solution sometimes.

Thanks for the help guys :]
 

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