I know this is an older thread but it's actually the latest one with reference to these speakers so here we go. I've read before that the Bluelines were produced for Ashdown by Sica. I think Sica is Italian. However, like a lot of people experiencing their Blues farting out I looked into replacements.
I have an ABM Mini 12T which, according to HHB came off of a promo tour with Steve Lawson. It sounded like crap when pushed. Its Blueline was labeled Celestion TrueVox, rated at about 150w. I was able to call a Celestion rep and order one rated at 250w that is holding up much better, but it is not blue.
I also have an ABM C110-300 combo that cried out in agony to be accompanied with an extension cab when pushed. It came with a BG10-150, not blue. The amp sounds much better with a 2510 DL II, though I still wouldn't gig it without an extension.
I have an ABM Mini 10H that has a Blueline, Sica from what I recall and remember that when I got the Deltalite in for the little combo I checked the fit into the Mini 10 Cab. Found that the hole was not large enough for the Deltalite to seat properly. It sounds ok as is paired with the combo.
Lastly is my ABM Mini 15. I'm not sure what's in it but it sounds good. The cab is rated at 300w, the speaker is blue, and I'm not going to break the seal on it just to find out what it is.
I can say that the Mini12T and the Mini15 paired under my ABM 500 sounds very good driven respectably hard.
Oh well....enough of my ramblings.