I still have my Keilidhs from 1994 and I use them as the rear speakers on my 5.1 system. I think they are great speakers and the key upgrades are the stone stands, renewing the tweeters if you had the Mk1 or Mk2 tweeters and the recap of the crossovers. The Hiquphon replacement tweeters are excellent and give a great improvement and recapping is easy to do and gives something extra. One key document to source is the Keilidh service manual from Linn. This is essential reading. You also learn that plus and minus are switched on early speakers (as indeed are mine) so you need to connect them out of phase with your other speakers in a 5.1 system !! The manual even tells you the serial number where they corrected this error ! Have fun - these are great speakers for their age and value.
HHB don’t leave us tied to that rock like Prometheus, spare us the pain and spill the serial numbers!
From the Asgaard chronicles: SN15400-20000.
Sorry about that- it is any speaker with a number below 15400 is out of phase
I have Keilidhs 1996 vintage from new. I recapped the crossover after a buzzing noise at certain frequencies in 2013 and also changed to Hiquphon OW1 bought direct from Oscar in Denmark at the same time. Lovely guy and his tweeters are even better!!
It was a profound upgrade across the board from bass to treble. I’ve been meaning to upgrade to the Monacor SPH-165 for ages. I can’t see a down side to them, easy to change back. No changes made to wadding or bracing, I do not see fiddling with this for the sake of it as worthwhile unless you know what your are doing.
The recap was a direct value for value capacitance replacement, depending on which caps you go for you might need to pair up to get a match.
In short, crossover recap ( I did the resisters as well), Hiquphon Ow-1 and Monacor SPH-165 as an excellent reversible upgrade in my view.
I’m currently trying to create a reason to keep my Hyquophon/Monacor upgraded Keilidhs as I don’t want to sell them. I’m thinking along the lines of an Atom in the spare bedroom. I don’t need another system but it wouldn’t be in the way 
Unless you kept the original drivers, and put them back to standard, it wouldn’t make sense to sell them. You’ll never recover the outlay of the new drivers. Either keep them in a second system or donate to friend or family member.
Hi Paul, I did see your review of the Monacors, I’d had already done my crossovers and Ow-1 so your post chimed with my thoughts hence why I’ll follow you with the SPH-165. Thanks.
Regarding second system, well we are in the same boat again. I did buy a pair of Keilidh in 2013 for donor drivers thinking the driver was pooped. As it was I figured it might be the crossover so recapped them fixing the issue but leaving me with a later pair of black keilidhs in the attic.
Last year I picked up a s/h Uniqute 2 in great condition, recapped the keilidhs but left the drivers. Sounds lovely in the kitchen dinner, so yes, an Atom I feel would work well. Enough of a presence at lower volumes but also plenty of drive and image when going louder. It’s a kitchen not a listening room.
Cheers