Tefag Cone Unit

• Brand: Teefag

The TEFAG Cone Unit is a balanced‑armature loudspeaker driver built on a substantial die‑cast base and fitted with a large permanent magnet. The design uses an unusually wide reed—over one inch near the supports—terminating in a forked end carrying two coils wound on moulded formers with integral mounting lugs. Laminated pole pieces are arranged to provide differential movement of the reed tips.

The unit employs a three‑point reed suspension with central screw adjustment. No damping is fitted. Contemporary test data reported good reproduction between 400 and 4,500 Hz, with noticeable resonances at 900 Hz and 3,200 Hz. Sensitivity was described as slightly below average, though free from chatter.

Technical Features

• Balanced‑armature reed driver for cone loudspeakers
• Permanent magnet of large dimensions
• Forked reed with dual wound coils
• Laminated pole pieces for differential armature motion
• Three‑point suspension with central adjustment screw
• No damping fitted
• Frequency range: good response 400–4,500 Hz (period test)
• Reported resonances: 900 Hz and 3,200 Hz

Manufactured in Germany by Telephonfabrik Berliner A.G. (TEFAG, Berlin) and then imported into Britain by Telephone Berliner (London) Ltd., who acted as the UK distributor.'

Here you find 7 models, 2 with images and 0 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Telephone Berliner (London) Ltd.; Hendon