91' Ampeg 2-15 cab: How did both speakers died simultaneously but the amp is fine?

B

benphelps

Jan 23, 2019
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#1
Howdy,

I'm trying to fix my ampeg 2x15 cab. It was made in 91 and has worked well until it recently went out at a show. Interestingly, this happened after another bassist's amp did the same thing. I checked the amp and it's fine. Also tried with different cables/amp heads to be sure. Connections to the cab and speakers also look fine. Both speakers read at 0 ohms which makes me think they both died. Is it possible that they could have both died at the same time? What might have caused that? If it was a power surge, wouldn't it have also messed up the amp? Thanks for your time.

Respectfully,

Ben

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#3
beans-on-toast said:
It would be best to test each speaker with the faston connectors removed at this point. Soy are just testing the speaker, not what it connects to.
Click to expand...

This ^ for certain.

Test directly at each speaker individually with nothing else connected to them.
Try the battery test and see if you get any voice coil/cone movement.

Sure they could have blown at the same time or very nearly at the same time. They could have been overpowered, voice coils burned open. The battery test will reveal a lot.

It is possible that something happened on the power grid that caused this and yet did not affect the amp, at least permanently. But this is much less likely, than the speakers getting blown (if they really are).

It's also possible that there is some sort of protection in the cabinet, like a fuse, or some other device.

You said this happened while it was out for a show? Were you there or was someone else using it?

Not odd at all if the same thing happened to another cab, and it also was being overpowered.
 
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#5
Note that OL means open circuit on most DMM's. Also, you might have the beeper function turned on. Before giving up hope on your speakers, make sure you're using the DMM in the way that you expect. Also, the 9-V battery test is a good way to check a speaker.
 
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#6
Doufuss said:
Test the tinsels.
Click to expand...

Almost 100% (say 99.99%) not this because of the style of lead-in wire on these drivers.

fdeck said:
Note that OL means open circuit on most DMM's. Also, you might have the beeper function turned on. Before giving up hope on your speakers, make sure you're using the DMM in the way that you expect. Also, the 9-V battery test is a good way to check a speaker.
Click to expand...
Agreed, what happens when the OP touches the leads together to verify that the meter is working properly?

If this was being used with the SVT amp, I would be surprised that the drivers were open without sounding absolutely awful first.
 
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#7
About 20 years ago, when I was playing in much-too-loud rock bands, I was running an Alembic F1-X pre-amp into a Stewart World 2.1 power amp (2100 watts!) into an Eden 410 cab.

Through the night the usual band volume competition set in, and I kept turning up. The next day I found two of the four tens were blown.

I don't recall hearing any sounds of speaker distress before the two died (or more accurately, were killed).
 
#8
rockdoc11 said:
About 20 years ago, when I was playing in much-too-loud rock bands, I was running an Alembic F1-X pre-amp into a Stewart World 2.1 power amp (2100 watts!) into an Eden 410 cab.

Through the night the usual band volume competition set in, and I kept turning up. The next day I found two of the four tens were blown.

I don't recall hearing any sounds of speaker distress before the two died (or more accurately, were killed).
Click to expand...
Your amp was much larger that the OP's amp. Your results were not unexpected.
 
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#9
agedhorse said:
Almost 100% (say 99.99%) not this because of the style of lead-in wire on these drivers.


Agreed, what happens when the OP touches the leads together to verify that the meter is working properly?

If this was being used with the SVT amp, I would be surprised that the drivers were open without sounding absolutely awful first.
Click to expand...

I'm saying test the tinsels because I had a failure at one of the joints between the tinsel and the faston tab. I only discovered the short by accident, as I had my multimeter hooked to the faston tabs via alligator clips, and had to move the speaker for some reason. I got a tone, so I knew the voice coil still worked. Manipulating the tinsel clearly indicated the short.

I repaired the joint, and got the cab working again.
 
#10
Doufuss said:
I'm saying test the tinsels because I had a failure at one of the joints between the tinsel and the faston tab. I only discovered the short by accident, as I had my multimeter hooked to the faston tabs via alligator clips, and had to move the speaker for some reason. I got a tone, so I knew the voice coil still worked. Manipulating the tinsel clearly indicated the short.

I repaired the joint, and got the cab working again.
Click to expand...

Open, not short
 
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#11
Not on that driver though. That’s a very robust lead-in wire style that I have not seen fail under that power level.
 
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