because they aren't.
different model.
the known pioneer is a PE-8.
the mystery speaker. is a PH-8.
i have a picture of a 'Fukuin Shokai Denki Seisakusho', field coil unit w/the same frame.
as soon as i find it i'll post the same.
as far as looking like a jensen, that may be.
after ww2, the usa literally colonized japan.
many things might be quite similar.
those in the usa may not have noticed,
the japanese certainly did ...