Pop/crackle in one speaker at only low frequencies in the tweeter

Odd problem here. I have some Silverline Audio SR 16 speakers which I just purchased used. They sound great. However I heard a pop (like what vinyl can do) when playing bass heavy music (not vinyl, digital served). I thought the subwoofer was rattling a connection as it did not sound like a speaker issue to me. I removed the sub and I thought it went away. Today I was running the stereophile test tones to dial the sub in at low frequencies. A pop or crackles appears in one tweeter at 50hz test tones and the few test tones below that. Nothing so far anywhere else in the frequency range but I have not been doing that much. I get the same pop/crackles thing with the sub removed and I play the tones thru just the monitors. It happens about 1/2 the time I run the test tones and only in the low bass area.  I did swap the speakers from right to left and the issue follow the speakers. I am running the speakers single wire and they have jumpers installed. 

Any ideas here?
 A pop or crackles appears in one tweeter at 50hz test tones and the few test tones below that.


50 hz for a tweeter? I don't think so.. unless you wired direct from an amp, with no XO.. The reason a speaker uses a crossover is to stop exactly what you're hearing..  If you're hearing it BELOW that you need to check out what is going on there.

60 hz and below is sub
60-250hz is bass
250-2500 mids
2500 up is tweeter or highs..

It sounds like you have a crossover problem. If you do, you might have a driver problem too. 

NO sound should be coming from drivers other than what the driver XO point have been set at.. 

So noise from the tweet, while doing low pass sweeps, is just as bad as 5k sweeps coming through the bass drivers...

Something is wrong.. look at wiring from the binding post to the XO give it the smell and a good visual.  Go from there.. 50hz signals getting through to a tweeter is not good though.. Snap, Crackle, POP, come to mind..

Thanks, kindof what my worry was. I am guess the xover. I'm gonna try to high pass the monitors (from subwoofer line levels) for now and see if that solves the issue. It really only comes up in rare times with actual music but I want as close to perfection as I can get. 
Just a follow up. When I removed the jumpers from the bi-wire terminals  I ran the woofers and tweets directly. No pop/.crackle at those specific low tone frequencies. I seem to only get it when running both drivers so suspect the resonance/vibration from the woofer is shaking a somewhat loose internal connection in xover or tweeter. I'm prob just going to leave as is I am more likely to mess something up than fixing I fear. I listened for an hour yesterday and heard it only once. It also seems to go away at lower volumes. Thx.
Obviously I can only guess but here it is. You have a loose wire in there. It may not be a tweeter wire at all. Open it up and take a look and add foam around the wires and make sure they are isolated..

good luck