Monday, May 8, 2023

The 1st listening test of the Pleiades 2N3053 single transistor power amplifier in stereo

At your risk. The design of such a system had been aided by listening in mono for many years until it souded almost perfect. How about now in stereo? Pleiades 2N3053 schematic description for each channel: 24V from 2 lead acid 1.2Ah batteries in series, + terminal to fuse holder with a 100mA fuse to one wire of primary of Sowter SK05s output transformer, other primary wire to the Collector of the 2N3053 transistor, either RCA/GE or Motorola, Emitter connected to battery -ve and signal ground, class A bias resistor 100Kohm to 200Kohm from Collector to Base using a series combination of fixed 100KOhm and 100KOhm variable resistor, music signal feeding the Base through a 10KOhm variable resistor (rheostat ie using only center and another terminal of a 10KOhm potentiometer), music electromagnetic signal output to all its pristine glory from the 8 Ohm secondary of this fabulous Sowter output transformer. This 1920's topology implemented with a small transistor may be miraculous. Commercial recordings may sound too good to be natural. On the other hand for example the pipe organ on the Alan Parsons Sound Check 2 CD sounds like being in an English church with the great long reverberation surrounding us. Pedal bass D does not sound creating intermodulation with upper parts of harmony. The train can burst you into laughter especially the squiking brakes.

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