The front panel.
Some options on what we can do with your Hehku’s front panel
The controller for power of the first preamp tubes. On top of the power, this channel influences the disturbance. Bright-option can be added through a pull-switch.
Bass, middle, treble
Classical passive tone stack. These controls influence the distortion of the channel. If you wish the sound to be as pure as possible, these controls should be left just slightly opened.
The pull switches can be used to add for example, bass shift and treble boost-features.
The volume controller for the second preamp tube works like the first one, with a slight difference being that it has a pull switch which controls EF86-tubes change from normal pentode-function to triode-function. In the triode-mode, the sound of the tube is softer and clearer with slightly lower volume. In pentode-mode, the volume is stronger and there is more distortion in the sound especially when the gain-function is opened.
Bass-controller in this channel can be either a traditional potentiometer or a rotary switch with six different settings. With the rotary switch, it is possible to cut and emphasise low frequences effectively without it affecting the higher frequencies.
Classical passive cutter for higher tones.
The controller for the distortion-channel’s distortion-function
The filter for the highest frequencies on the distortion-channel. This controller doesn’t affect the lower distortion-levels that much, but the effect is multiplied as the amount of distortion grows.
Controller that is in charge of the level of the distortion-channel.
Controller for the general tone. It cuts frequences from all the channels and its affect depends on the master-controller’s setting.
Controller for the general power. When you’re looking for a clear sound, this controller should be opened as wide as possible, so that the gain-controllers on the preamps can be as shut as possible.
Speed and intensity.
The tubes take a while to heat up once the amplifier is switched on, after which it is ready to use.
Not a necessity in low wattage amplifiers.