Download Automated Equalization for Room Resonance Suppression Estimating room resonances in locations of big events and looking for counter-measures are normally done by sound engineers, mainly before the beginning of the event. In this paper an automation to enhance the audio quality in event rooms by suppressing the room resonances with a parametric equalizer of several high-Q peak filters is proposed. The room characteristics can be identified with few measurements in the listening area during the event, without applying an additional measuring signal (using its original sound signal). Based on this room characteristics the equalization filters are automatically designed. The results of several rooms tested with the automated equalization for room resonance suppression are presented as well as a discussion on the covered topics.
Download The Influence of Small Variations in a Simplified Guitar Amplifier Model A strongly simplified guitar amplifier model, consisting of four stages, is presented. The exponential sweep technique is used to measure the frequency dependent harmonic spectra. The influence of small variations of the system parameters on the harmonic components is analyzed. The differences of the spectra are explained and visualized.
Download Discretization of Parametric Analog Circuits for Real-Time Simulations The real-time simulation of analog circuits by digital systems becomes problematic when parametric components like potentiometers are involved. In this case the coefficients defining the digital system will change and have to be adapted. One common solution is to recalculate the coefficients in real-time, a possibly computationally expensive operation. With a view to the simulation using state-space representations, two parametric subcircuits found in typical guitar amplifiers are analyzed, namely the tone stack, a linear passive network used as simple equalizer and a distorting preamplifier, limiting the signal amplitude with LEDs. Solutions using trapezoidal rule discretization are presented and discussed. It is shown, that the computational costs in case of recalculation of the coefficients are reduced compared to the related DK-method, due to minimized matrix formulations. The simulation results are compared to reference data and show good match.
Download Analysis and Simulation of an Analog Guitar Compressor The digital modeling of guitar effect units requires a high physical similarity between the model and the analog reference. The famous MXR DynaComp is used to sustain the guitar sound. In this work its complex circuit is analyzed and simulated by using state-space representations. The equations for the calculation of important parameters within the circuit are derived in detail and a mathematical description of the operational transconductance amplifier is given. In addition the digital model is compared to the original unit.
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.