Dimples on Speaker Spades

What's the purpose of these dimples on these speaker cable terminations?



These are WBT-680 spades. These dimples sit proud of the spades and are only on one side. This end is connected to my amps,

I never thought anything of them as they worked fine with my previous amp but using a new amp with CHK binding posts, these spades do not grip well enough and can be relatively easily pulled out.

I'm tempted to file the dimples off or replace the spades.

 

I went to WBT's website and in their renderings of this connector, they do not show any dimples.

 

Yes I've seen that but they only show the one side. My spades are from 2014:

http://www.wbtusa.com/pdf/0660.pdf

 

Could it possibly be to prevent the spade from turning when you tighten down on the retaining nut?

 

Well, it doesn't work if that's the case!

 

The dimples stick out, and concentrate the contact on small points. This creates much higher pressure in these areas, magnifying the clamping force, and may make for less intermittent connections as the "bump" material may even be forced to deform.

I would blame the problem on the posts. They aren't clamping down as hard as needed to create adequate friction. This may be because of poor threading, which creates resistance when you are screwing them down, so you stop tightening prematurely. The bumps also may cause rotational friction that give you the impression they are tight when they are not.