Western Electric tube amplifiers - 310A 328A 154C Trans

Western Electric tube amplifiers - 310A 328A 154C Trans

This Buy-It-Now auction is for two (2 pcs.) Western Electric J64001-W vacuum tube amplifiers.

These are high quality Western Electric tube amplifiers, which were used for testing accuracy of other

Western Electric audio transmission systems and components.

As can be seen in the photo scans of Bell System literature below, these are:

"principally a three-tube amplifier, with frequency weighting obtained from characteristics of interstage

coupling and a varistor type rectifier" .

The C-Message Weighting filter (extra inductors and capacitors between 1st and 2nd tube stages) purposefully changed the

output characteristics of the amplifier from flat response to give a C-Message Weighting response curve. This is basically

a Band-Pass filter placed between the output of the first tube stage and the input of the second tube stage.

The band-pass filter inductors and capacitors between the 1st and 2nd tube stages need to be bypassed to return the

amplifier output to flat frequency response. The interstage wiring between the first and second tube stages should be changed

to closely resemble the wiring circuit between the 2nd and 3rd stage. See schematic diagram below.

The input trans is the
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