Chapter Five: Power Amplifier
5.1
Tone and Volume of the Power Amplifier
5.1.1
Master Volume
As the name suggests, this controls the overall, global volume of the amplifier.
For your enjoyment, there is also a second programmable master volume control,
which allows volume adjustments via remote control while you are playing. Both
controls are laid out so that even a low-performance effects unit can be used and
amplified in the loops.
5.1.2
Presence
This knob controls frequencies over 3KHz. Treble is produced and dispersed in a
very small beam from the speaker, so be sure to position yourself in the projection
area of the speaker when making adjustments.
5.1.3
Deep
The Deep control is an active bass control, contrary to conventional bass controls.
It controls the frequencies around 120Hz without influencing the overall dynamic
range of the power amplifier. Diezel Co. is not responsible for disintegrating
speaker cabinets.
5.2
Power Amplifier Tubes
5.2.1
Function
As the name suggests, the power amp section is the part of the amplifier that
produces output power, measured in watts. Preamp signals are sent to the power
amp(s), which amplifies this signal to a level that is acceptable for loudspeakers.
Guitar amplifiers utilize several different types of power amps, which differ in
output power and tone. We chose the tube type power amplifier for its tried-and-
true performance and familiar tonal behavior.
5.2.2
Selection
Diezel Co. installs the most reliable and best sounding tubes that are currently
available in sufficient quantities. So it is possible that tube brand and tube type
will change during production. You can fine-tune your Herbert by having
different type and brands of tubes installed, however, it is imperative that the amp
is biased properly. Herbert utilizes 6 power tubes, organized in 3 pairs with triple
bias possibility. This allows use of 3 different pairs of power tubes, either the
same or different types. Yes, this means that you can mix 6550’s with EL34’s, or
6L6’s with KT88’s etc. Cool, no?
