I've owned this '60 Tweed Pro for 30 years (it used to belong to Eldon Shamblin of Bob Wills and the Texas Playboys), and hated the 15” speaker for just as long. Tried every 15” known to man, “best” was an old Altec 418B, which was still awful, just less so. Finally had to decide to either sell this thing or make it right. So I broke out the router and made a reducer ring from 15” to 12”, and put a proper speaker in it. Now it sounds unbelievable, can’t wait to bring it to the gig Friday.