G.R.A.S. Sound & Vibration
Sound-intensity Probe Type 50AI - Page 6
1.1.2 Preamplifiers
The small ¼″ diameter and 40 mm long microphone preamplifiers (Fig. 1.4) are housed in
robust, stainless steel casings which enable novel probe designs that reduce disturbances to
the sound field otherwise brought about by the effects of shadows and diffraction. Symmetry of
design enables reliable calibrations as described in the proposed standard (ISO/DIS 9614-2) for
sound power measurements using sound-intensity measurements.
Fig. 1.3 Showing similar pairs of phase-matched ½″ microphone cartridges
Above: Type 40AK, which includes spacers and three adapters for
¼″ preamplifiers as supplied with the Type 50AI.
Below: Type 40AI, which includes cartridges only
Fig. 1.4 Pair of ¼″ Preamplifiers Type 26AA supplied with the Type 50AI
Fig. 1.5 Showing the various spacers and the spacer cup supplied with the Type 50AI
RA0263
100 mm spacer
RA0264
50 mm spacer
RA0265
25 mm spacer
RA0266
12 mm spacer
GR0040
Spacer cup
