However, it is often neglected that the correct positioning of the loudspeakers and a well-chosen listening position have an even more significant effect on sound quality than many tuning measures. It is best to first try to optimize the position of the loudspeakers and the listening position before moving on to further fine-tuning. Because only an optimally set up system is able to make the sonic advantages of further measures audible.
While massive sound improvements can be achieved in the mid-range and high-frequency range of loudspeakers by simple means such as toeing in the loudspeakers or carpeting, the quality of bass reproduction depends almost exclusively on the room dimensions and the correct placement of speakers and listening position. The main reason for this is that HiFi loudspeakers radiate the deep bass component (below 100Hz) spherically. While the mid-range and high-frequency range is radiated more or less directionally forwards, the bass spreads indiscriminately in all directions. This means to the back wall, side walls, ceiling and floor. The sound waves are repeatedly reflected by the walls; these "standing waves" (room modes) massively disturb the sound image. Some bass tones are reproduced much too loudly, others are completely cancelled out. Unfortunately, deep bass tones cannot be combated with carpets or simple foam absorbers. However, since the phenomenon of room modes has a different effect at each point in the room, there are ways to get room modes under control by cleverly positioning the speakers. If you have problems with bass that is too strong or too weak, you should therefore first "wander" through the room with your armchair and listen to music or bass tones at different points.
You will notice that the bass differs at each listening position. Often less bass is perceptible in the middle of the room, while near the wall the bass becomes louder and louder. The same effect can also be achieved by moving the loudspeakers: If the speakers are close to the wall, the bass becomes louder but less precise. The further the speakers are placed from the walls, the more precise and leaner the bass range becomes. Ideally, you will find a placement option and a listening position in which your room supports the speakers instead of disturbing them. Perfectly positioned, a speaker in a good listening room plays fuller and more powerfully than in an anechoic chamber.
As a tool for calculating the frequencies at which room modes occur, you can, for example, use the room mode calculator from Dr. J. Hunecke Hunecke Room Mode Calculator.
On the left image you can see the first order longitudinal modes: At the front and back of the room, there is a strong bass boost at approx. 31 Hz. The right image shows the first order transverse modes at approx. 50 Hz. Ideally, your listening position should be in an area that is largely free of room modes.
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