XBL patent prior art fra 1976?

[Snickers-is]

Jeg siterer min egen tråd fra DIYaudio...:

I really can not find any difference between the claims of Mr Wiggins in this patent from 2006:

Patent link 7,039,213

And this patent from Dallas company Babbco Ltd in 1976, figure 9:

Patent link 3,983,337

The last one (from 1976) describes the use of twin coils in combination with a single gap to provide the same effect as what is described as the XBL technology. However, this section is interesting:



Here is Fig 9:

And here are Fig 6-8:

Have I missed something or is this just another prior art patent?