Re: KM184 - recording distance for classical guitar?
Author: Uwe Sattler/NeumannUSA
Date: 10/12/2012
The frequency response curve depicted elsewhere on this website for the KM184 is shown per IEC 60268-4 at a distance of 1m, which is fairly close to your recording distance. At this or larger distances you are well enough outside the range where proximity effect will make much of a noticeable difference. In addition, you are aiming the microphones at an angle of approximately 45 degrees to the sound source, which significantly reduces the proximity effect already. (Proximity effect is most pronounced for direct zero degree sound incidence to the diaphragm).
By taking advantage of the proximity effect, a KM184 would exhibit a flat frequency response down to 20 Hz at a distance between diaphragm and sound source of around 35 cm. On axis at that 20 Hz frequency increasing the recording distance from 1 m to 2 m will reduce the output by a barely perceptible 2.5 dB, and a 50 Hz the difference will alredy be diminished to less than 0.8 dB. The real change will probably be more due to room acoustics, and in the end you may have to disregard the scientific method and still resort to experimentation...