Guitar Pre-Amps

Guitar preamplifiers can be built to produce any sound from clean to crunchy, to highly distorted and sustained.

In terms of overdrive and distortion, the aim is to be able to retain the original sound that comes from the string: this is achieved at relatively high distortion and sustain levels.

The EQs in the preamplifiers are of the passive type in order to keep the original sound.

Extra features are a send/return loop and also relay systems that can be activated by foot switches so as to select different channels.

Guitar Power Amps

In terms of power, amps can be designed that have anywhere from 3 watts to 400watts for guitar and bass.

Power levels can be switchable on the same amp.

Beam tetrodes and pentodes are mainly used, but also triodes if required for guitar amps.

For clean and tight bass amps, triode or ultra-linear configurations can be used if necessary. The classes of guitar amps designed are A, AB1, AB2 and B. Single ended guitar amps (A1, A2) up to 50 watts can also be designed and built.

The choice belongs to the customer and most of these types/classes of output operation can be contained and switched between in the same amp.

Theo prefers not to use negative feedback at the output stage, but if necessary, global negative feedback can be switched into the amp.

In the negative feedback loop, an EQ system can be incorporated into the power stage, where the guitar speaker and output transformer form part of it.

Rectification can be valve, solid state, or mixture of both, and switchable.

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