Other Wireless World Amplifiers

The Wireless World Quality Amplifier was the principle amplifier for Wireless World projects from 1934 to 1946. However there were other amplifier designs published during this time.  Here are a few of them. Note that although octal valves were released in 1935 these were an American invention and rarely used in British designs until after the war.  British valves had 4V heaters and usually B5 or B7 bases, though Mazda did have its own octal base nowadays called "Mazda octal", but sometimes called "British octal". 


The Wireless World Negative Feed-back Amplifier.


An Inexpensive Amplifier: With negative feed-back. A cheap design is not necessarily nasty. M.G. Scroggie, B.Sc., A.M.I.E.E. 

Notes - EL33 or KT61 would be an easier valve to obtain to build this circuit today, though quite expensive.  A cheaper alternative would be the EL821 (6CH6) which has very similar characteristics.  Applying negative feedback over two transformers can be risky though, so anyone building this amp would need to be prepared to do a bit of experimenting.


Wireless World AC/DC Quality Amplifier.  (PDF)

1948 January

High-Quality Amplifier Design. Advantages of Tetrodes in the Output Stage. P.J. Baxandall