Riverstone Audio 6P1P-EV (6П1П-EB) NOS Tested-Matched Quad (4pc) - Upgrade for 9-pin 6P1 and 6P1P Vacuum Tubes- Platinum Grade Quad, 6P1P-EV (6П1П-EB)

Tested AND Matched Quad 6P1P-EB (6П1П-EB) NOS Vacuum Tubes. These vintage NOS vacuum tubes are an excellent replacement for Chinese 6P1 and Russian 6P1P tubes that are used in amplifer circuits. During parameter testing at our workshop, all tubes are subjected to multiple test cycles and are matched within 3% for both plate current (ip) and mutual conductance (Gm). Fewer than 50% of the NOS 6P1P-EV tubes we test meet our high standards for audio use and are selected for these Platinum Grade Matched-Quads. You will not find a more rigorously tested set of vacuum tubes anywhere. PLEASE NOTE: 6P1P-EV tubes can only be used as a direct replacement for Chinese 6P1 and Russian 6P1P tubes. 6P1P-EV tubes should not be used to replace other types of 9-pin vacuum tubes - AMPLIFIER DAMAGE CAN OCCUR IF YOU SUBSTITUTE THE WRONG TYPE OF TUBE. WARRANTY: we have confidence in our products and guarantee that these tubes will test at NOS levels when received AND we back these tubes with a no-nonsense two-year money-back warranty. To protect the tubes during shipping and storage, 6P1P-EV tubes are supplied in Riverstone Audio's custom "tube cradle" boxes. All vacuum tubes sold by Riverstone Audio will have the "Riverstone Audio" name, logo and QC label on the tube box.

• Matched Quad (4 pcs) 6P1P-EV (6П1П-EB) NOS Vacuum Tubes. The 6P1P-EV vacuum tube is a vintage Soviet-made miniature 9-pin beam-tetrode. The “-EB” designation at the end of the 6P1P tube code designates a long-life (E) and high-reliability (B) version of the 6P1P tube. 6P1P-EV tubes have an average life of 5000 h, compared to 3000 h for 6P1P tubes.
• UPGRADE FOR 6P1 and 6P1P VACUUM TUBES – Please Note: 6P1P-EV tubes can only be used as a direct replacement for Chinese 6P1 and Russian 6P1P tubes. AMPLIFIER DAMAGE CAN OCCUR IF YOU SUBSTITUTE THE WRONG TYPE OF TUBE - Carefully determine the type of tube used in your headphone or amplifier before ordering.
• TESTED AND MATCHED by experienced engineers using Amplitrex tube testers to evaluate the electrical parameters of the tubes (additional details of Riverstone Audio's test facility can be found under our Amazon listing for 5654W tubes). The tubes are evaluated for plate current (ip), mutual conductance, tube gain, leakage and noise. If any deficiencies are found the tubes are not sold. Less than 50% of the 6P1P-EV tubes we test and audition pass our standard for high-fidelity audio use and are used in our Platinum Grade Pairs and Quads.
• TEST RESULTS CLEARLY MARKED on the tube boxes with data for ip and Gm attached to the individual tube boxes. The tubes chosen for these matched pairs have close electrical parameter matching (ip and Gm macthing between the four tubes is guaranteed to be within 3%). The matched quads will have identical date codes.
• BUY WITH CONFIDENCE - Our Platinum Grade 6P1P-EV vacuum tubes are backed by Riverstone Audio’s no-nonsense 2-year warranty - THE BEST WARRANTY AVAILABLE in the audio tube business. We also guarantee that the tubes selected for our Platinum Grade matched pairs test will test at NOS levels when received. To protect the tubes during shipping and storage, the 6P1P-EV tubes are supplied in Riverstone Audio’s custom “Tube Cradle” boxes.