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This one has me scratching my chin. I repaired a LabSeries L5 ss combo that came in sounding quite bad. I gave it a good cleaning, and replaced the input jacks, but it still didn't sound right. It broke up in a bad way and rattled certain notes. so I put it on the scope and measured a clean sine wave right up to full power of 115 watts. Speakers, I wonder? So I played the amp thru another 2 x 12 cab and it sounded good, so I call the customer and tell him the bad news. You need one or more speakers. He gives the OK to pull the trigger on a used pair of GTT-75's at $100 or below.
While I am waiting I pull the two CTS original speakers from the cab. While they are out I try to find a problem with one or both of them, but I cannot. I drive each one with a clean test amp, and then both together and they actually sound pretty darn good! Puzzled, I wonder if it's the cab somehow, perhaps the stapled on grill cloth panel interacting with the baffle board. I put the speakers back in the cab with their 8 machine threaded 1 1/4" screws. I check the cab with the test amp and they sound good. Then I test the cab with the original amp and they sound good!
How did these speakers heal themselves? When I was testing them they were laying on their backs, so maybe something got dislodged from the gap? I suppose a way to tell would be if there is a piece of something in the gap, if it were ever to happen again, laying the amp on it's back and playing thru it should have the same effect of dropping the grit back down. I suppose then one would cut off the dust cap and carefully vacuum the gap?
While I am waiting I pull the two CTS original speakers from the cab. While they are out I try to find a problem with one or both of them, but I cannot. I drive each one with a clean test amp, and then both together and they actually sound pretty darn good! Puzzled, I wonder if it's the cab somehow, perhaps the stapled on grill cloth panel interacting with the baffle board. I put the speakers back in the cab with their 8 machine threaded 1 1/4" screws. I check the cab with the test amp and they sound good. Then I test the cab with the original amp and they sound good!
How did these speakers heal themselves? When I was testing them they were laying on their backs, so maybe something got dislodged from the gap? I suppose a way to tell would be if there is a piece of something in the gap, if it were ever to happen again, laying the amp on it's back and playing thru it should have the same effect of dropping the grit back down. I suppose then one would cut off the dust cap and carefully vacuum the gap?
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