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Old 05-20-2013, 06:50 AM
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merrylander merrylander is offline
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Most of those twin triode 12nn7s had the heaters centre tapped so that they could also run off 6 volts. Running an 8 volt heater at 6 volts should prolong the tube's life. That is if the heater will heat the cathode enough to make it emit electrons.
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