Celestion C12 Louspeaker reed 1927 vintage radio wireless

This is the Celestion C12 loudspeaker made by the Celestion Radio Company, Kingston-Upon-Thames, Surrey, England in 1927. This 'reed' type loudspeaker is well made and is signed and dated on the inside, presumably by the person who made it. The paper cone is stiffened with a spiral of wire (visible in the photograph above) and there is a rotary sensitivity adjustment at the back of the unit.

The example from my collection was not working when I acquired it and the fault was traced to one of the two energising coils having gone open-circuit. The contemporary picture below shows the magnetic components of the reed mechanism.

Open circuit windings were quite a common problem with coils and transformers from this period which used very fine silk or cotton covered wire. Occasionally this fine wire corrodes, possibly due to acid contamination from the hands of the coil winder, and eventually fails. In this case, however  I found that the termination near the centre of the bobbin was not soldered, and showed no sign of ever having been soldered! I rewound the coil and this fine loudspeaker now speaks again. It has a winding resistance of 1250 Ohms and is very sensitive. In fact I have connected this loudspeaker to my GECoPHONE No. 1 Crystal Detector Set and, with a good aerial and earth and some careful adjustment, I have been able to follow a local transmission in a very quiet room. In fact the sound is audible (just!) up to 10 feet away!

A contemporary advertisement for this loudspeaker is shown below.

Eventually I will place a sound file here so that you can hear what it sounds like.

 

Copyright 2001 - 2002 Lorne Clark