My first (non-rack-system) speakers were SM 150+'s; my brother later owned SM 155's, SM 125's & an SM center. So I'm very familiar with the SM lines over the years, although I've not listened to the later ones (the ones where the woofer looks like a whitewall tire:thumbsdn: ).
First off, the SM's are easy to drive and will play
very, very loud! But for a big speaker they really aren't that good in the bass region. They will move a lot of air but don't go really deep. For drums and bass they're pretty powerful, but don't expect all that much with recordings of orchestral kettle drums or pipe organ.
Secondly, the SM's are the very definition of "pet coffins." They're large, unbraced and nearly undamped boxes. Very honky with a lot of box coloration. But I really kick myself now that I never tried to mod them. I suspect you could very easily & cheaply reduce box colorations by gluing in some carefully cut dowls and either filling the cabs with some lambs wool/rock wool/ fiberfill. Brian Cheney of VMPS mentioned using dowls to brace cabs, but that didn't occur to me "back in the day." BTW, I've heard of guys doing this to mod similar monkey coffins from Cerwin-Vega. Fwiw I've been told the big CV's can be modded to sound exceptionally good, but I haven't tried them.
As for sound- it could be rose colored glasses, but I feel the earlier versions like I had sounded better and had better bass than the later ones. My brother is very familiar with both and wholeheartedly concurs. The earliest ones may have been tuned lower, but they seemed to have better deep bass. I'll tell you what got my brother off the bubble; I brought a pair of Monitor Audio Bronze 2's (med sized bookshelf speakers) over and set them up next to his SM 155's. The MA's completely annihilated the big SMs in every catagory, save max volume and bass extension. Granted, they couldn't match the sheer scale of the SM's, but the sound was much cleaner & more detailed. I'm not sure how fair the compro is- the SM's, while more expensive, were older. And a well designed bookshelf will probably sound cleaner than an inexpensive floorstander. Although in all honesty I think my brother paid nearly a thousand dollars on the big SMs.
Would I recommend them? After years of listening to several models in the SM line over a decade and a half, I'd say: maybe. It depends on the price and whether you're inclined to try modding them. My brother ended up selling them to a friend for a pretty decent price, but if you could get them for $200-$250 I'd say they're probably worth it. The Poly-Cell tweeter, though not SotA, isn't bad- reasonably detailed, more polite than harsh. The mids aren't the last word in transparency either, but again if you're willing to take the time and spend just a few bucks to mod the cabs I suspect a lot of that honky box coloration would go away.
Bone-stock I'd say they're pretty decent rock speakers. They'll play hard with little power, plus they'll handle the full output of a pretty big amp with no complaint or power compression. Someday, when I have a bigger house and an adequate shop/project area I'd like to put my money where my mouth is and aquire a pair to experiment with & modify.
Anyway, I hope this is helpful to you.
