All Hand turned, Brass construction soundbox by ASTRA of London, "ASTRA ELECTRIC" , dating to the early 1920's & based on the Seymour  Superphone soundbox design but with the addition of a useful triangular needle port for using Fibre needles. The diaphragm is impregnated, pressed, composite silk & quite large. The tone is very nice.  It has recently had new rubber isolators fitted to the rear tonearm fixing & diaphragm. The soundbox measures a massive 76 mm Diameter. 

This soundbox was touted by The Gramophone Exchange as being "More Human & less Gramophony than any other soundbox, at present on the market" !  

& was reviewed by the Gramophone magazine......

."By far, the best result was given by the ASTRA, which gave a beautiful, open tone."

Astra went on to work with the likes of E.M.G & EXPERT according to the excellent Gramophone museum site.

the rear tonearm fixing is around 18 mm internally / 19 mm externally 

supplied in what appears to be it's original carton.  

  thanks for looking