I'm sorry, but the link above is not correct.
RINGO was never released in any multi-channel format. The artwork for a RINGO Quad-8 is a Photoshop forgery.
For 720-pages on all things solo-Beatles, check out the book Eight Arms To Hold You.
I defer to your knowledge, of course, but I also have to stand up for mine. No where on that page do I infer that the "Ringo" album was mixed or released in quad. Check it out and read what I wrote. The label that is on that page was in fact sold (for quite a large amount) on eBay, I don't recall the date but it was almost 20 years ago, and if it was faked they did a great job, but again, that page does NOT state that the title was prepared, mixed, or ever released