National (GE) 6550 Gold Line Matched Pair Tubes, New Old Stock (NOS)


The other set of these we listed sold out in under an hour.

This set of tubes is actually a New Old Stock (NOS) matched pair set.

We believe these to be NOS GE Tubes rebranded under National's Gold Line Series.

They have matching date codes and test close enough to one another to operate as a matched pair. Our calibrated modern and professional Amplitrex AT-1000 Tester indicated a 5% Plate Current Match, 3% Gm Match.

For reference we generally see plate current between 40-60% for NOS tubes on the Amplitrex. (This value can vary due to different internal construction).

We test all of our 6550s with 450V on the plates. Results are written in the following format.

Plate Current % of NOS Spec / Gm % of NOS Spec - Plate Current in mA

Tube 1:  55% / 98% - 33.4 mA
Tube 2:  60% / 95% - 36.4102587 mA



Original Box

Yes Included


Not Applicable


Not Applicable


Not Applicable

Physical Condition

9 / 10

Working Condition

10 / 10

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