Microphone Amplifier 1 Type: GAI

Marconi Co. (Marconiphone, Marconi's Wireless Telegraph Co. Ltd.), GB (not tubes - see also HMV His Master's Voice)

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  • Year
  • 1923 ?
  • Category
  • Audio Amplifier or -mixer
  • Radiomuseum.org ID
  • 345041

 Technical Specifications

  • Number of Tubes
  • 5
  • Wave bands
  • - without
  • Power type and voltage
  • Powered by external power supply or a main unit. / 6 / DC 300 Volt
  • Loudspeaker
  • - For headphones or amp.
  • Material
  • Wooden case
  • from Radiomuseum.org
  • Model: Microphone Amplifier 1 Type: GAI - Marconi Co. Marconiphone,
  • Shape
  • Tablemodel, with any shape - general.
  • Dimensions (WHD)
  • 625 x 405 x 300 mm / 24.6 x 15.9 x 11.8 inch
  • Notes

  • Marconi Type GA1 single-channel, five-valve microphone amplifier, having resistance-capacitance interstage coupling with metal screening boxes over the valves.

    To reduce microphonic noises each valve was connected by gold plate contacts mounted on a sub-assembly and suspended by rubber bands, with flexible leads to the main circuits.

    The amplifier had provision for adjusting the high-frequency response to suit the acoustic properties of the hall the microphone was used in.

    This was the standard BBC microphone amplifier for several years.

    It operated from a 6 V filament supply and a 300 V HT supply.

  • Net weight (2.2 lb = 1 kg)
  • 45.7 kg / 100 lb 10.6 oz (100.661 lb)
  • Mentioned in
  • -- Original prospect or advert (Microphone Engineering Handbook ISBN 0 7506 1199 5, Page 279)

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The model Microphone Amplifier 1 is part of the collections of the following members.

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