Filament voltage

Prairie Dog · 1487

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Offline Prairie Dog

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on: February 14, 2013, 12:05:35 PM
Hello, folks
I just took delivery of a pair of EML 300Bs for my Paramounts with soft start.  The info sheet in the box has me a little paranoid, claiming no guarantee on tubes operated outside of the 5% tolerance range for filament voltage.

The line fluctuates between 118.5 and 120.5, when the electric furnace etc kicks in.

The filament voltage varies from 4.57 to 4.74 with the EMLs, about 100mV or so higher with the ELectroHarmonix.

I read in another post one could raise the fil. voltage by inserting a cap at the choke input.  Any ideas on a range of values to try or am I worrying needlessly?  At the price point of these tubes I'd like to be sure I'm not shortening their lifespan.

Any help is, as always, greatly appreciated...