This is a nearly pristine Bell and Howell powered extension speaker design for use with film projectors or record players. This one was likely built in early 1961. The input jack of this amplifier is connected to a 16-ohm, 25-Watt resistor, and the amp only has one gain stage before the phase inverter. So, it’s made to be be driven by another amplifier. The output from a guitar or mic is too low to fully drive the output stage.
In elementary school, whenever we had any kind of presentation or a dance, one or more of these B&H powered extension speakers was used in the auditorium to make sure everybody could hear.
The power amplifier section is cathode-biased, using two 6L6GCs to produce about 25 watts RMS. The 6L6GCs in this amplifier are absolutely gorgeous clear top RCAs. The date code shows them to be a built in 1959 or so.
After carefully testing all of the capacitors, I replaced all of the electrolytics and a few leaky couplers. Also, all of the pins and jacks were thoroughly cleaned.
For the sound demonstration, I simply used the headphone Jack from a tiny solid-state Fender Bronco to drive this amplifier. The pre-amp is set to be completely clean. So, the little bit of grit you’re hearing is from pushing the output stage hard.
Негізгі бет B&H 25-watt Extension Speaker Post-repair test
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