AUDIO HOWLING

Radio Record, Volume I, Issue 21, 9 December 1927, Page 5

AUDIO HOWLING

In a cascade, three stage amplifier, using transformers as a means of coupling between the valves, trouble is often experienced due to howling between stages, although each stage may work satisfactorily by itself. In some cases if the connections to the primaries of each transformer are reversed, the howling will cease, "I'ransformers should be placed as far as possible from one another, and care should be taken that their cores are always placed at right angles to one another, as, should they be close and in parallel, the fields of each would interact, thus causing distortion, howling, and bad amplification. It is advisable to earth the casing of each shielded low frequency transformer.