Cones appear to be pulling INWARD during playing.

[beans-on-toast]

Play a note. Speaker cones suck and blow air in equal amounts, it's how they work.

Is there any chance that the port is blocked. Weird things can get into ports. Since it is rear ported, it should not be right up against a wall. There has to be room for airflow. Like the speakers, air moves in and out of the port. Blocking it can affect cone movement.

 

[agedhorse]

Speaker cables handle a LOT of current when playing loud. Poor cables can have resistance that cause power loss and bad damping of the speaker cone movement. My advise is to buy a quality cable that you can trust and take it from there. The last thing you want is to bring something unreliable to a gig.

Even an 18 gauge cable for bass guitar applications is plenty fine and the losses will be tiny (including any impacts on damping). The length is too short to matter.

That said, quality cables are very important for reliability. Especially SpeakOn plugs, which should be Neutrik branded and not knock-off look alikes. These tend to become intermittent, or get stuck in the mating jacks.

 

[Kokoskaka]

Yes, this is absolutely true, as long as the cable is actually made from copper (and not copper plated steel, which is not that uncommon in chinese knockoffs), and as long as it is terminated well and the connectors are not hanging by a few poorly soldered strands of wire.

 

[agedhorse]

Yes, this is absolutely true, as long as the cable is actually made from copper (and not copper plated steel, which is not that uncommon in chinese knockoffs), and as long as it is terminated well and the connectors are not hanging by a few poorly soldered strands of wire.

The knock-off cables that aren't copper are usually CCA (copper clad aluminum) which is very fracture prone.

SpeakOn plugs should never be soldered. The wire should never be tinned either.

 

[4-stringB]

Is it a completely stock cab? The reason I ask, is that back in the days of yore, I put a speaker designed for an acoustic suspension cab into a vented cab. The speaker could pump air out of the cab better that it could draw air back in. This resulted in the cone being drawn back to nearly the rearmost limit of it's travel for brief moments, during heavy usage...Just a thought. EDIT#2...beans-on-toast has good ideas, too.