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Amperex

2x Amperex EL84 6BQ5 Tubes - Bugle Boy Label - Vienna 1966 KM4

2x Amperex EL84 6BQ5 Tubes - Bugle Boy Label - Vienna 1966 KM4

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Product Summary

Model: 1966 Amperex EL84 6BQ5 (Made in Austria)

Soundlumia Tube Sound Rating9.0/10 - Outstanding 

Date codes:
KM4 A6E2 (KM4 = EL84 production gen #4, A = Vienna, Austria, 6 = 1966, E = May, 2 = Week 2 of the production month)
KM4 A6E4 (KM4 = EL84 production gen #4, A = Vienna, Austria, 6 = 1966, E = May, 4 = Week 4 of the production month)

GM (Mutual Conductance) test result: 79%/98% of NOS/NEW

Silkscreen: 90% - 100%

Packaging: New white box

Professional Tube Testing

Tube 1: 

Measured transconductance (GM): 8.88 mA/V  - 79%  (100% = 11.30 mA/V)
Measured plate current (IA): 29.605 mA  - 62%  (100% = 48mA)

Tube 2:

Measured transconductance (GM): 11.13 mA/V  - 98%  (100% = 11.30 mA/V)
Measured plate current (IA): 44.77 mA  - 93%  (100% = 48mA)

NO shorts, leakage or gas. NO noise or microphonics.

Curve trace is also included in the original RoeTest report.
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