Download A Csound Opcode for a Triode Stage of a Vacuum Tube Amplifier The Csound audio programming language adheres to the inputoutput paradigm and provides a large number of specialized commands (called opcodes) for processing output signals from input signals. Therefore it is not directly suitable for component modeling of analog circuitry. This contribution describes an attempt to virtual analog modeling and presents a Csound opcode for a triode stage of a vacuum tube amplifier. Externally it communicates with other opcodes via input and output signals at the sample rate. Internally it uses an established wave digital filter model of a standard triode. The opcode is available as library module.
Download Simulation of a Vacuum-Tube Push-Pull Guitar Power Amplifier Power amplifiers play an important role in producing of guitar sound. Therefore, the modeling of guitar amplifiers must also include a power amplifier. In this paper, a push-pull guitar tube power amplifier, including an output transformer and influence of a loudspeaker, is simulated in different levels of complexity in order to find a simplified model of an amplifier with regards to accuracy and computational efficiency.
Download A Physically-motivated Triode Model for Circuit Simulations A new model for triodes of type 12AX7 is presented, featuring simple and continuously differentiable equations. The description is physically-motivated and enables a good replication of the grid current. Free parameters in the equations are fitted to reference data originated from measurements of practical triodes. It is shown, that the equations are able to characterize the properties of real tubes in good accordance. Results of the model itself and when embedded in an amplifier simulation are presented and align well.
Download Block Processing Strategies for Computationally Efficient Dynamic Range Controllers This paper presents several strategies for designing Dynamic Range Controllers when using a block-based processing scheme instead of sample-by-sample processing scheme. The processes of energy measurement, gain calculus, and time constant selection are executed only once per each new incoming block of samples. Then, a simple and continuous gain update is computed and applied sample-by-sample between continuous sample blocks to achieve good sound quality and performance. This approach allows reducing the computational cost needs while maintaining the flexibility and behavior of sample-by-sample processing solutions. Several implementation optimizations are also presented for reducing the computational cost and achieving a flexible and better sounding dynamic curve using configurable soft knees or gain tables. The proposed approach has been tested and implemented in a modern DSP, achieving satisfactory results with a considerable computational costs saving.