R&D Report 1961-12 : AKG electrostatic microphones Types C26 and C28. H.D. Harwood, J.R. Chew, R.L. Deane, R.J. Packer This report describes tests on two electrostatic microphones manufactured by the Akustische und Kino-Gerate Gesellschaft (A.K.G.). The first, type C26, has omnidirectional and the second, type C28, cardioid characteristics. The microphones are of small dimensions and provision is made in each case for introducing an extension piece between the capsule and the head amplifier. Two types of wind shield are provided; one can be fitted over the end of the microphone itself, whilst the other is designed to protect the microphone capsule when an extension piece is used. Measurements have been made of the microphone frequency characteristics with and without the various fittings, and the degree of interference from wind and from magnetic fields has also been determined. The quality of reproduction obtained, particularly from the type C28, is good and the degree of interference is low. The susceptibility to radio-frequency fields has also been measured and a method of reducing it has been indicated.