Ok so BIG update.
First the speakers now sound fantastic, and there was no real magic to it…it really came down to just letting the foams settle and break in.
When chatting with Simply Speakers they said they shouldn’t need to break in…but they really did. After about 10 hours of playing, the difference wasn’t just noticeable, it was night and day different. The sound had gone from being thin and lacking in bass to a beautiful full, warm, and bouncing note.
I hugely appreciate all the guidance, support, and assistance from everyone here…..annoyingly it could have been avoided is SS had just said, ‘give them a few hours to break in’ regarding the foams.
As for the ‘mystery woofers’. I have now given the speakers to my Dad, (he is over the moon btw!) so I was able to ask him about the history…..so, the woofers are originals, but one got damaged in a house move back in the mid 80’s so my Dad’s friend, Bill, who had actually worked for Advent re-coned them for him. Although they look slightly different, they were made by the same manufacturer and were direct replacements used by Advent in repairs at that time. My Dads pal re-coned both just to ensure there were no minor differences between the original 10 years old cone.
Hopefully that puts this ‘issue’ to bed, and again…thanks to everyone for your support.
I have essentially fallen in love with the speakers and am currently awaiting a pair of my own I just won on auction!! I am thinking I may try the BSC as proposed by
@Pete B so the adventure continues!!