The 3677s's have been "temporary" for about 6 months while I dither about whether the 2226J's from the 4648 and the 3677 horns are going in 7 Pi's. They sound damn fine in the little 4.5 cu ft cabs so I'm in no hurry. Have to do the turntable first. The link is the discussion about crossovers. Don't remember about Zobel but Wayne recommends against with the 2226. With your M115's I don't know but there is also a post with the T-S parameters: search "3677".