OP, not sure how helpful this will be, if at all. However, for what it's worth, back in the day (i.e. late 60's/early 70's), Cerwin Vega and JBL were two major brands that folks who enjoy the type of music you do would often gravitate to and buy. I could tell you which of the two I preferred but such information would be absolutely useless because speakers, more than virtually any other home audio system component, are a very subjective and personal choice. I have no idea what your definition of "probably old" is. However, I would caution you to beware of "old" speakers with foam surrounds, unless they've been recently re-foamed.
advice re old shelf speakers
hi all. hoping for some guidance. i am after a pair of, probably old, shelf speakers as cost is a major factor. how they look/condition unimportant. just need to be able to handle all sorts of music and be LOUD! i care for my mother as has dementia, so funds tight. all good though, i just have to be creative and do the research. example, i have a pretty decent old technics midi separates system eh600 which i found on gumtree for £50 in mint condition. perfect. i have run audio to it through a good quality optical out from tv to a fiio k5 pro dac/amp then line out to line in on the technics. now volume nicely boosted and sounds good and clean as also quality leads and upgraded 4 wire type speaker cables. for v little spend it does a decent job, but i love my music so always looking for more and i feel my neighbours really need to listen to more slayer, rush, jinjer, etc. the technics speakers are pretty decent but now struggling a bit with the added oomph i can now get out of my system. had no real idea where to start, then thought there may be some wonderfully helpful people out there with the knowledge and patience to help me. fingers crossed and thanks v much in advance if it's you. apologies for the long post. gerald