NIB NOS Matched Pair CBS-Hytron USA 12BZ7 [12AX7 Sub] Black Plate Vacuum Tubes

Tube Type / Number: 12BZ7 [12AX7 Sub]
Actual Brand*: CBS-Hytron
Printed Brand: CBS
Quantity of Tubes: Matched Pair
Plate Construction: Black Ribbed
Getter Construction: Top Fat D
Country of Manufacture: USA
Visible Date Codes: HG & XO
Lettering Condition: 50 Percent
Year Made:
Mica Spacers: 2
Smoked Glass? No
Engraved Base? No
Boxes Included? 2 Boxes - Both Original
Notes: Copper Getter Post. The 12BZ7 has the same gain factor as the 12AX7 and draws twice the heater current. Since preamp tube don't draw too much current, almost any amplifier should have no issue with this. Theese are great substitutes for the 12AX7 - Why break the bank?

Gm Test Results: 32/27 & 32/28
Minimum Good Value: 17/17
NOS Test Value: 27/27
Life Calculation: 100+% (where 65% = fail)

Tests as NOS?: Yes
True NOS?*: No

** Please note, many tubes will test NOS but will actually have a few hours of use on them. A truly NOS tube will have excellent getter flashing condition, no dirt/grime, usually in the original box, and no filament deposits. If a tube is listed  as "tests NOS" but is listed as "not True NOS" please expect the tube to have a small amount of use *

All tubes have been tested using only the best tube testers. We have a large fleet of tube testers, and every single one of them has been calibrated within the last year by industry experts. We mainly use the Hickok TV-7D/U, but occasionally we may use a Hickok 539, 533A, or 600A.