Riverstone Audio - 7-pin 6J1P-EV (61-EB) NOS Vacuum Tubes, One Pair Fully-Tested and Matched (5% for IP and Gm) - Upgrade for 6J1 6J1P 6AK5 5654 EF95 403B - 2 pc 6J1P-EV (61-) 5%-Match

Description

• Tested and matched pair (2 tubes) of vintage Voskhod 7-pin NOS 6J1P-EV (cyrillic 61-) Vacuum Tubes. An excellent audio-quality replacement for 6J1 / 6J1P / 5654 / 6AK5 / EF95 tubes. Tubes that do not meet our stadards are never sold.
• Riverstone Audio fully tests and matches these tubes to within 5% for both plate current (ip) and mutual conductance (Gm); for some data codes, where we have large quantities for testing, the parameter matching is usually much closer (NOTE: parameter matching within 10% is more than sufficient for all high fidelity audio applications). If you have a specialized application, or desire 6J1P-EV tubes with a guaranteed match within 3%, please visit our Amazon Storefront. Data labels showing measured ip and Gm are attached to the tube boxes.
• We guarantee that the NOS 6J1P-EV tubes selected for our Platinum Grade matched pairs will test at NOS levels at or above 4500 micro-mho with a plate current of 6.0 mA or higher (these values correspond to fixed-bias testing at Vp = Vg = 120 V using Amplitrex AT1000 test units). After two decades testing Vintage US and Russian vacuum tubes, we have confidence in our vacuum tubes - Riverstone Audio's platinum grade tube sets are backed by our no-nonsense 2-year warranty, which is the best in the audio tube business.
• Amplifier damage can occur if you substitute the wrong type of tube. 6J1P-EV tubes should only be used to replace the following 7-pin tubes: 6J1 / 6J1P / 6AK5 / 5654W/6AK5W/403B and EF95 tubes. DO NOT substiture for other types of 7-pin vacuum tube unless this tube is approved as a substitute by the manufacturer of your audio device. Certain hybrid amplifier circuits can also utilize 6J1P and 6J1P-EV tubes as a replacement for tubes such as 6J2, 6J2P, 6K4, 6K4P and 5725W (this will be specified in the owner's manual for your amplifier). if unsure about a substitution, please contact Riverstone Audio or the manufacturer of your amplifier for information regarding allowable tubes).
• The vacuum tubes are protected during shipment using Riverstone Audio tube boxes, with internal sleeves to protect the tubes. Our products will always have the Riverstone Audio logo, QC labels and tamper-proof seal on the outer packing boxes.
• Vintage 6J1P-EV (61-) vacuum tubes can be readily identified by the three vertical grooves in the glass shell; these grooves, molded in the glass, are the key fingerprint to identify authentic Voskhod 6J1P and 6J1P-EV vacuum tubes. Other identifiers include the saucer-shaped getter holder and the horizontal Voskhod rocket logo - please see listing images for futher details. 6J1 and 6J2 tubes will not have grooves in the glass and will have a rectangular getter-holder.
• If you do not require data labels, we also offer the identical 6J1P-EV tubes at a slightly lower cost (we refer to these tubes as "Gold Grade") which have a shorter burn-in (12 h), but the identical testing and matching procedures used for our Platinum Grade matched tubes (for our Platinum Grade tubes we utilize a 24 h burn in). We have confidence in our testing procedures - our Gold Grade tubes also have the identical 2-year warranty as our Platinum Grade matched pairs.

One pair, fully-tested and matched 7-pin 6J1P-EV (61-) vacuum tubes. These vintage Russian vacuum tubes provide high audio quality and can be used as a direct replacement for 6J1, 6J1P, 6AK5, 5654W, 403B and EF95 vacuum tubes. The -EV suffix (-EB in cyrillic spelling) designates a military-grade long-life version of the standard-grade Russian 6J1P (61) vacuum tube. 6J1P-EV (61-) vacuum tubes can be readily identified by the three vertical grooves moulded into the glass shell, a saucer-shaped getter holder and the horizontal Voskhod "Rocket" logo printed on the tube directly above "61-" (see listing images for futher details). Chinese-manufactured 6J1 tubes will not have grooves in the glass and will have a rectangular-shape getter. As with vintage US-manufactured 5654W vacuum tubes, true NOS 6J1P-EV tubes are becoming increasingly difficult to obtain in sufficient quantities to allow the matching of test parameteres. Fortunately, a decade ago, we purchased and stored a large quantity of 6J1P-EV tubes and are now selecting the best of these for our tested and matched pairs. Prior to matching, the tubes are rigorously tested (plate current (ip), mutual conductance (Gm), gas/noise) using Amplitrex AT1000 tube testers; the vacuum tubes are guaranteed to be matched within 5% for both ip and Gm. For certain manufacture years, where we have large quantities favailable for parameter matching, the matching will be even closer. If closer parameter matching is desired for your application, please see our Amazon Storefront for our listing that has the same tubes with a guaranteed match within 3%). NOTE: In gerneral, the matching of ip and Gm within 10% is more than adequate for all audio applications - closer electrical parameter matching is rarely required, except for very specialized applications. Please note that the test results we provide (plate current and mutual conductance) correspond to results obtained using Amplitrex AT1000 testers; other tube testers may provide higher or lower measured values. As an expample, for 6J1P-EV tubes, ip will typically be higher if tested on the Russian L3-3 or Chinese GS-5A tube testers, as these units utilize much different test circuits and test parameters. From data comparision tests we have made with our in-house Amplitrex, L3-3 and GS-5A test units, and using identical sets of 6j1P-EV tubes, the L3-3 and GS-5A testers show ip values approx. 0.5 mA to 1.2 mA higher than the Amplitrex AT1000. Again, identical tubes tested on different testers, but significantly different test circuits, test parameters and corresponding NOS-range for ip and Gm.

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