This combo amp was developed by Leo Fender for Music Man and built in 1980. It has two channels, one supplied with reverb and phaser effects. The output power of 150 watts is delivered into four 10 inch speakers mounted into the cabinet. HD stands for heavy duty and right! the amp has a weight of 39 kgs. Even with the chanel volume at 10 this amp won't sound distorted. The tubes are of the 6L6 type.