This Fender 1965 Bandmaster amplifier was completely gone through before going to a studio.
This project consisted of testing tubes for a client. The tubes came from Europe and were manufactured during the end of the Cold War. With the tubes being used in a cathode bias (self bias) amplifier, it was important to match the tubes as closely as possible.
The Music Man amplifiers are an interesting blending of solid state and vacuum tube technology.
The early versions of the JCM2000 were prone to an issue that has been coined the “bias drift” issue. It’s been discussed at length on countless fan forums and since around mid-2004 the issue was resolved in manufacturing by Marshall.
Desert Amplifier Repair Specializes in Ampeg V4 Service and Restoration, with dozens of V series amplifiers having been on the bench.