I've been using my crack with the speedball upgrade for about a year now with no problems and have been greatly enjoying it. A couple weeks ago I upgraded the output capacitors to Audyn 100uf 400v and bought a NOS 6AS7G tube. Besides some occasionally humming with the new tube everything seemed to be working well after the upgrade until a couple days ago.
I turned on the crack and plugged in my headphones about 10 seconds later. After 5 more seconds I heard a loud pop in the left driver and unfortunately found that the driver had been burned out. It only plays at about 30% the volume of the right driver now.
I turned off the crack and examined and reflowed all the joints. I found that the joint at B3 was barely attached and the wire could wiggle around slightly. After reflowing B3 the amp appears to be working well and passes all the speedball voltage checks, but I am still hesitant to put a nice pair of headphones back into the amp until I am sure that I have solved the problem. Would a bad connection at B3 explain the reason for the left driver burning out?
Thanks for the help,
-Ryan