The key components of this bright-boost circuit are the volume control RV and the bypass capacitor CBP. Bass frequencies are attenuated by the volume control's voltage divider effect, but treble bleeds past via the capacitor. The capacitor has no effect with the volume control set to maximum. It has the most effect at low control settings, when brightening is usually the most desired. Other components in the circuit include the coupling capacitor CG, which is designed to pass audio but block DC, and the grid stopper RGS which combines with the inter-electrode capacitance of the second triode to attenuate radio frequencies.
The calculator above computes the gain at various frequencies based on the capacitor value and volume control setting. It assumes the coupling capacitor CG is large enough to be considered a short circuit for guitar frequencies. This is almost always the case. It also assumes that attenuation due to RGS is only significant above audio frequencies, also a common assumption.
This new approach to guitar amplifier electronics embraces 2018 technology to deliver greater understanding with less math. Computer-based visualization replaces the traditional litany of mathematical formulas. The book's graphing calculators, free on this website, are designed for smartphones and laptops, making them as portable as the book that uses them.
Less Math, Greater Understanding
The book explains the principles of vacuum tube electronics and the design of preamp voltage amplification stages, cathode followers, tone stacks, power amps, phase inverters, negative feedback, and power supplies. An entire chapter is devoted to sculpting the dynamics of overdrive and harmonic distortion.
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