AMPEG V4-BH Query.

[rictified]

Yes one or more of those are frequently open in 70's heads. I don't think any of the newer stuff is as reliable or sounds as good as an SVT though even though it's nice stuff, the best in my opinion you can buy today.
The old heads are extremely reliable as are all old Ampegs, there are many unrestored B-15's and SVT's still in use today and back in the 60's and 70's most people didn't take care of them like they do today, it was much cheaper to fix them back then. I have a 1959 Ampeg Bassamp that works great and sounds good in original condition except for a different speaker and a couple of 70's heads which although I restored them like Greg and Jared mentioned sound great and never fail. My 87 skunkworks head is all original except I put 12DW7's in it with a slight mod to accomplish this.