Polarity is correct!!!!

I have an old Peavey 2 x 15 cabinet that I loaded with two cast frame 400 watt EV 15's that look like this;

http://images.search.yahoo.com/imag...hmv&sigi=1175qs5fr&.crumb=eAIKtGLT/4B&fr=ipad

I just recently sealed up the ports on this cabinet to see if it would tighten up the sound. Each speaker has it's own compartment and does not have the air pressure influence from the other speaker.

Here's the twist; when I play an open E or A string, the speakers vibrate at the frequency being played, but one slowly moves outward from its frame and the other pulls inward deeper into its frame. Each are still vibrating at frequency.

I've checked and re-checked the polarity by using a 9 volt battery and touching the batt. terminals to the tip and ring / ground of a speaker cable plugged in the cabinet. Both speakers always move in the same direction.

Is the slow drift of the cones in opposite direction the result of one compartment not being sealed as good as the other? What are the other possibilities?

 

Since both drivers are in the same cabinet, they are generally in the same light. As for the excursion of the EV drivers, it's may not be as extreme as some newer speakers, but it's not difficult to see, and it's the primary reason these speakers still work. I've been down the road with extreme xMax speakers. They sound fantastic at first, but I haven't found one that will hold up for long. I'll admit that I've only tried a couple; it's a rather expensive experiment, but the couple I've tried started sounding like Buddy Holly's guitar speakers after about 15 - 20 gigs.

 

I would guess a bit of both. I'm sort of building a retro rig consisting of a Fender Studio Bass amp section built into a head and the old Peavey 2x15 cabinet. I got the cab for almost nothing, & I had the speakers, so I loaded them up. The best I could measure the shelf porting, it was wrong for the T/S parameters of the drivers. It sounded like it, too.

The shelf port was going to be almost impossible to modify, so I thought I would try sealing up each compartment. That more or less eliminates cabinet tuning and is much more forgiving; as long as the cabinet volume isn't too small or way too big, the speaker does its thing. Each compartment of the cabinet is 3.18 cu. ft. which is not optimum, but within the range for the T/S parameters of the drivers. The cabinet performance is greatly improved, but then I noticed the opposite drift in the drivers when allowing a long sustained note while searching for "air leaks".

I think I discovered the issue. Even though the two drivers are identical, one has been re-coned. When I swap their position in the cabinet, each driver continues to act the same, eliminating the cabinet as the cause. Perhaps the re-coned VC winding starts on the VC former at the opposite end from the original? Not sure on that, no way to tell.

There doesn't seem to be any phase canceling, so I'm going with it. The sealed cabinet does wonders to tighten up the low end when using the tube amp. It was sloppy when driving the cabinet with the tube amp when the cab was still ported, which is why I started this journey.....

 

Here's a look at the beast. I had to replace a board in the grill frame that I didn't paint and does it ever show up with flash!!

Also need to get the grunge off the back of the cab, but that pic is to show the mobility mods. Casters from hardware store and bathroom grab bar for disabled. $14 + $18.