The PGS had a pair of perforated fibre plates located either side of the ribbon which, by resonance, maintained the HF response to around 18kHz. For the 4038 the perforated case was recessed on both sides to perform this function, thus achieving quite a big cost saving.
Internal hum neutralizing wiring coupled with magnetic shielding of the toroidal ribbon-to-microphone line transformer reduces response to stray magnetic fields by 30 to 40 dB.
For many years, the 4038 was found in virtually all BH studios. Indeed, many studios were equipped with no other type of mic.
The mic is still made today but by Coles Electroacoustics of Hoddesdon, Hertfordshire.
