is a rsl a rogers speaker?

Bought the 3600s, a good JBL4311 copy. Dome tweeter, level controls, ported with typical midbass bump.
Reasonably sensitive, easy on amps and would play pretty loud.

If I found some today, in good shape, they make fine speakers in the '2nd string system'....with a Vintage Sansui amp and a Dual TT........

All ported speakers have a double hump.

I once had an equalizer with cal'd mic and a warble tone generator. Had to turn down either the 60 or 125hz with my 3600s and it helped a LOT.

Room has bunches to do with what you hear, of course. If you got lucky and have a room and a listening postion which eats that frequency, so much the better. I was never quite so lucky.