Product Summary
Model: 1964 Philips EL84 6BQ5 (Made in Holland)
Soundlumia Tube Sound Rating: 9.0/10 - Outstanding
Date codes:
Delta 4J2 (delta = Heerlen, Holland, 4 = 1964, J = October, 2 = 2nd week of the month)
Delta 4E3 (delta = Heerlen, Holland, 4 = 1964, E = May, 3 = 3rd week of the month)
GM (Mutual Conductance) test result: 165%/136% of NOS/NEW
Silkscreen: 90% - 100%
Packaging: New white box
Professional Tube Testing
NO shorts, leakage or gas. NO noise or microphonics.
This tube tested NOS (100%+ mutual conductance value for NOS/NEW) on a reliable Mercury 2000 tube tester with the following result (mutual conductance both in uMhos and in percentage of NOS/NEW value):
Tube 1: 4,125 (165%)
Tube 2: 3,410 (136%)
Good tubes start at 1,200 and new tubes (incl. NOS/NIB) 2,500, and the Mercury 2000's rated mutual conductance for new EF86 tube is 2,500. Test result can also be seen in the pictures. In case you wonder what all these numbers mean to your sound experience, it's actually quite straightforward: mutual conductance directly translates to a tube's ability to amplify sound, so the higher the numbers the better.
