Blackstar S1-104EL34 Series One 100-Watt Tube Guitar Amp Head with EL34 Power Tubes
Four EL34 power valves form the backbone of this 100W high gain power house and provide unbelievable dynamics and head-room. The DPR control allows the power to be reduced down to 10W for beautiful power amp distortion at a much lower volume level. Setting new standards in tonal flexibility, the deceptively simple preamp section has four world-beating channels (6 modes) which are further augmented by dual ISF controls. With Series One customisation comes as standard and you will effectively design your own sound.

ISF CONTROL
The ISF control works in conjunction with the Tone control. It allows you to choose the exact tone signature you prefer. Fully CCW is a more American characteristic with a tight bottom end and more aggressive middle, and fully CW is a British characteristic which is more woody and less aggressive.