Frequently asked questions.

What are first reflections?
First reflections are those vibrations that first hit a wall and are reflected back to the ear. These reflections can massively influence the direct sound of the loudspeakers. The result is overemphasis or cancellation of certain frequencies and thus an enormous influence or distortion of the sound. First reflections occur at the walls, the ceiling and the floor. They should be dispersed by diffusers or absorbed by absorbers.

How to locate first reflection points?
Sound waves are reflected by walls. So when the sound hits a wall it is reflected back. These reflections work according to a simple principle: angle of incidence = angle of reflection.
A simple and accurate method to find the critical points of the initial reflections is the mirror trick: You sit down on your listening position and have someone walk flat along the wall with a mirror. When you can see the front of the speaker in the mirror, you have found the position where you should act against the first reflections. This method is done for the left speaker against the left wall and the right speaker against the right wall. The mirror method can be used both on the wall and on the ceiling and in virtually any room situation.

Reverberation time
In addition to suppressing initial reflections, the reverberation time in the room is also important. This is usually specified with the value RT60 (Reverb Time 60). This value indicates how many seconds the reverberation takes to decay by 60 dB in relation to the output level. In control rooms of recording studios, a very short reverberation time with an RT60 value of approx. 0.25 - 0.3 seconds has become established. In HiFi rooms and home cinemas, on the other hand, the reverberation time should be about 0.5 seconds.
To reduce the reverberation time, broadband absorbers are recommended because they are effective over a wide frequency range. Rooms with extremely short reverberation times (< 0.5 seconds) are perceived by some people as very unpleasant, in this respect absorbers should be used very selectively.

What is the LEDE principle?
LEDE is the abbreviation for "Live End Dead End". This principle is often used in control rooms of recording studios as a basis for acoustic optimization. Here, the front half of the room around the monitoring speakers is acoustically damped, while in the rear half of the room, around the monitoring position, the sound is diffusely reflected, thus increasing the diffusivity.