MUSIC MAN 130HD
The Music Man Amplifiers are an interesting blending of solid state and vacuum tube technology. This amplifier comes from the Leo Fender era, after his sale of Fender Musical Instruments to CBS and prior to Ernie Ball purchasing the Music Man company.
The Music Man 130HD model saw a good amount of fame and was played by such notable artists as Eric Clapton for a time. Other than the combination of a solid state preamp and tube driven power section, the design is unique in that it runs almost 650VDC on the output tubes, causing them to run extremely hot and clear.
With these high voltages, regular bias checks and preventive maintenance are highly encouraged. It takes a thorough understanding of tube limitation to set the bias correctly and not red plate the tubes. If you were to simply set the bias as you would any Fender or Marshall, the tube life would be measured in minutes.
Another safety issue worth mentioning is that Music Man wired the fuse holder reversed, so in the event the fuse blows it holds hot power, which can build up heat on the fuse canister. This can cause the fuse holder to melt, causing a possible short to the chassis and create a shocking hazard. These amplifiers should always be run with an earth ground power cord (3 prong).