c1964 Bird Golden Eagle 4/25, courtesy of Music Ground, Leeds, England
The next development from the Golden Eagle 2/15. The 4/25 had an increased power output of 25 watts produced by twin EL34 or perhaps KT66 valves. In order to handle this large increase in power, a 15" speaker was fitted. This was a twin channel amp, i.e. 2 x 2 inputs with individual volume and tone controls for each channel. Tremolo was fitted to one channel, and the spring reverb acted on both channels. In addition, a "sort-of" repetitive echo was fitted - a feature no doubt to enable the amp to compete with the new Watkins Joker, which had a complete tape echo unit built in. The Bird's echo was not tape driven however, but used a valve circuit in conjunction with the spring reverb to give a vaguely similar effect.