Jecklin Disk
From the inventor of the Jecklin disc with effective advertising name " OSS disc " (Optimum Stereo Signal) was called. It is a device to realize stereo recordings. The method is distinguished by the fact that with relatively little technical effort - with good acoustic conditions - natural sounding recordings can be made . The process goes back to the Swiss radio sound engineer Jürg Jecklin.
Construction
An OSS or Jecklin - up consists of a sound-absorbent material -coated, 30 cm in diameter measuring wheel. This disc is positioned as a partition, ie, a separator between two omnidirectional microphones. The microphone base between two microphone capsules amounts to 16.5 cm - middle ear as a distance by an adult assumed value (2 x 8.25 cm = 16.5 cm), corresponding to a time difference Δ t maximum of 0.48 ms corresponds to. The quasi- "ear signals" both microphones are recorded on each with its own soundtrack; see also binaural sound recording.
Principle of operation
A composition with Jecklin disc produces a stereo signal, in which the direction information is represented both by time differences as well as by frequency-dependent sound pressure level differences. The arrangement of the two positioned at 16.5 cm distance microphones generates the head-like run-time differences. The Jecklin disc itself caused by shading the sides of incoming sound waves significantly frequency-dependent level differences Δ L, the increase to the high frequencies and decrease greatly to the low frequencies, ie below 500 Hz are pure mono. These specific signal differences are called spectral differences.
Characteristic properties of a recording with Jecklin disc
When using a Jecklin disc and microphones with omnidirectional sound coloration are due to lateral sound incidence to be expected by comb filter effects, which are generally but little conspicuous.
Due to the tendency of low frequency sound - stronger than high frequency noise - to objects located in the propagation path to be bent around the level difference between left and right signal for different frequencies are different. For obliquely incident sound with decreasing frequency drops when using a Jecklin disc with diameter of 30 cm, the level difference left / right below a cutoff frequency of 500 Hz, so that in practical operation, the left-right signals in the bass range in levels are the same. Below 500 Hz, the signals are considered to be mono.
New window: OSS technology ( Jecklin disk)
Texts that do not originate from the inventor, there is not. Add new scripts from Jürg Jecklin one finds an enlarged disc diameter of 35 cm, and now even more than doubled microphone base of 36 cm (distance between the microphone capsules from each other ). In contrast, the earlier disc had a smaller diameter of 30 cm and a much smaller microphone base of 16.5 cm, which probably should replicate the ear distance.
" OSS technology ( Jecklin disk) Two ball microphones are arranged with a mutual spacing of 36 cm and covered with acoustically separated by a sheet of foam of 35 cm diameter. In this arrangement, the sonic benefits of the ball microphones to their full advantage. The right, angle-dependent delay differences arising from distance of the two microphones, the level differences and spectral differences by the acoustic separation of the disc. The two microphones must have a linear diffuse-field frequency response. Perfect for this arrangement is to be the microphone DPA 4006 with black diffuse-field essay. "