The MESA Bigblock 750 has a built-in overdrive channel. The Mesa M2000 has a high gain switch that can be engaged with a footswitch. The Marshall MB450 head and combo bass amplifiers have a tube pre-amp on the "Classic" channel that can be overdriven. The Ashdown ABM 500 EVO III 575W Bass amp head has a built-in overdrive effect. Overdrive is also available on many Crate bass amplifiers. The Yamaha BBT500H has three types of built-in drive effects: overdrive, distortion and fuzz. The Ampeg B5R Bass Amplifier has two channels: clean and overdrive, with the ability to combine the two. The Orange has introduced a new line of bass amplifiers(OB 1 series) with a built in fuzz.