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Old 12-24-2017, 10:22 AM
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benman94 benman94 is offline
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Join Date: Jun 2011
Location: Detroit, MI
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Well the math works out anyway. The 6C5 is more than capable of providing the necessary voltage swing according to the RCA 6C5 datasheet.

Since the output stage of two 2A3s/6B4Gs/6A5Gs is operating in fixed bias at the "standard" datasheet operating points, the grids of the output valves only need about 124 volts peak between them to drive the output stage into clipping. The output stage is class AB1, so the current draw of the grids is negligible.

The output stage requires 124 volts (peak) between the grids. 124 volts on the secondary would require the 6C5 to swing about 42 volts (peak) on the primary, which is well within the abilities of the tube. The 6C5 will be "loafing", so the distortion from the driver stage should be quite low. The distortion of the output stage will predominate, and a total THD for the entire amplifier should be ~3.5% just before clipping. Not bad for pre-war technology with no feedback.

This all assumes I can keep the B+ voltage stiff enough. The power supply simulates well so I'm not terribly worried about B+ regulation.
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