True NOS Date & Gain Matched Pair Brimar CV4004 [12AX7 ECC83] - Box Plate Tubes

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Tube Type / Number: CV4004 [12AX7 ECC83]
Actual Brand*: Brimar
Printed Brand: Valve Electronic
Quantity: 2 Pieces-Matched Pair
Matching Date Codes? Yes
Plate Construction: Grey Wing/Box
Getter Construction: Top O
Country of Manufacture: England
Visible Date Codes: XE KB/AD
Lettering Condition: 90 Percent
Number of Mica Spacers: 2
Mica Shape: Saw
Smoked Glass? Clear
Engraved Base? No
Boxes (always included): All WB/Generic
Notes: Gain: 88.5/90.7 & 90.0/90.2
Tested For & Matched By: Gm & Gain on a Maxi-Matcher Preamp @ real world voltages

Gm Test Results: 1626/1706 & 1662/1712

Minimum Good Value: 975/975
NOS Test Value: 1500/1500
Life Calculation: 100%+% (where 65% = fail)

Tests as NOS?: Yes
True NOS?*: Yes

** 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.


All of our tubes are 100% guaranteed to arrive as described, test as described and to be void of any sound defects. We offer a 30 day return window from the day you receive the item.

PLEASE NOTE - While we accept returns for basically any fault, we DO NOT accept returns for buyer's remorse which includes buyers who decide they don't like the subjective tonal signature of a tube. We have had people exploit our generous return policy to tube roll on our dime so we have a strict policy against this behavior.

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