Hi, Jinder (also known as one of the reasons i bought my J45 Early) i use Spectrums a lot. amazing strings, and beautiful as well. i've been on a round core kick for a while, Newtones on the Early right now, the Spectrums, 12s and 13s are probably the best sounding best quality strings i've used, although as you said they are not for every guitar, but i've found that the tension is less than others i use, and to me, a 12 sounds like a 12 but feels like an 11, which may be true of most round cores, but particularly true of these. maybe it's the real silk they use. i use their BeBop strings on 4 different hollow body electrics and will probably never change! hope you're doing well. Rick