Speaker simulation

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With speaker simulation is called for a one electronic circuit that simulates the electrical characteristics of a speaker. It is used in order to be able to carry out measurements in amplifier construction without having to connect a real loudspeaker (which would mean a considerable amount of noise protection in the case of sinusoidal tones emitted with several hundred watts and also make extremely high demands on the long-term load capacity of the loudspeakers.). In the simplest case, a loudspeaker simulator consists of a resistor that converts electrical energy into heat. Two-way or multi-way loudspeaker systems with corresponding characteristics can be mapped using additional circuit elements.

An electronic audio device is also referred to as loudspeaker simulation, which is preferably switched between headphone output and recording input or line-out and recording input when recording music . It is used when an amplifier test with a microphone does not seem sensible or possible. Of course, the speaker simulation is limited to instruments that have an amplifier output. Purely acoustic musical instruments and orchestras made from them cannot be captured by a loudspeaker simulation, just as singing voices or choirs.

The signal voltage at the line-out socket, for example from a guitar amplifier, is usually richer in harmonics than a signal recorded with a microphone close to the loudspeaker. This is noticeable in a “sharper” sound impression. In addition, the characteristic increases and decreases in individual frequency ranges caused by resonance phenomena are missing . Furthermore, the characteristic influences of the power amplifier used in interaction with the otherwise used loudspeaker are missing. The speaker simulation changes the input audio signal in such a way that there are only very slight differences in sound compared to the usual sound recording via the conventional way via signal chain from (guitar) amplifier, power amplifier, loudspeaker and microphone.

One variant assumes that the user wants to integrate the sound character of his power amplifier into the overall sound. Therefore, these devices must convert the power of the amplifier (usually up to 200 watts) into heat and generate a signal with a suitable output level for recording.

Technically, this is implemented by an analog or digital filter circuit that simulates the frequency response and phase response of the loudspeaker (and the microphone picking it up). Ideally, the impulse response of the conventional recording process is simulated so that the simulated result largely corresponds to the original. Advanced systems can also simulate the influences of the recording room, so that the simulated end result can only be distinguished from the original by trained ears. In the case of software-based solutions, these are either implemented as plug-ins for common studio recording software or as physical devices with DSP processors which, with their massive computing power, enable very high-quality results.

The disadvantage is the lower number of options available to the user of a loudspeaker simulation when using it, since he can only choose from the number of available sound variants (selection of the implemented loudspeakers, microphones, microphone positions, room influences) and not adequately like the sound engineer in one equipped recording studio with an infinite number of variations to create the desired sound.

A big advantage, however, is the great cost efficiency through the simulation of many loudspeakers / amplifiers / microphones, which in reality can quickly cost several tens of thousands of euros. Another advantage is that it enables realistic recordings with very high sound quality in the living room at home without burdening the neighbors with the sound level normally required for this from the real loudspeakers. Since the recording room also has a large share in the result achieved, it is also not necessary to set up an adequate room for this, which further increases the cost advantage.

Modern loudspeaker simulations can reproduce different loudspeaker characters via digital processors, taking into account the various microphones, microphone positions and room situations used.

Individual evidence

1. ↑ Self, Douglas: Audio Power Amplifier Design Handbook, p. 241 ff