Brand New In Box 6973 Electro-Harmonix Vacuum Tubes - Matched Quad. We only sell factory fresh tubes and NOT seconds as we are an authorized dealer for New Sensor (EHX) and JJ. Thanks to Electro-Harmonix the 6973 is finally affordable and easy to find! This tube has long caused grief as the originals are so scarce.The two are related, however a 6CZ5 would break up far too early and would burn out prematurely as they cannot handle the voltage of a true 6973. This is a rich and warm sounding tube with great dynamics just like the original. You can run these in any circuit that calls for 6973 or 6CZ5 but you cannot run a 6CZ5 in place of a 6973. We test and/or match our tubes by Gm & Plate Current using a state of the art digital Maxi-Matcher tube tester. The Maxi-Matcher simulates a real circuit and tests tubes in real-world conditions.
We also check our tubes for other issues like shorts on calibrated and vintage tube testers. We match our tubes +/- 5% with an overall tolerance of 10%. While we do screen for noise and microphonics, even the best tube testers are quite bad at finding these faults. The only real test is with your ears.We guarantee that our tubes will be free of noise or microphonics but please be aware that there isn't a whole lot we can do to ensure your tube won't be. We guarantee our tubes for 90 days upon receipt. Noise and/or microphonic issues are covered. The item "Brand New In Box Current Matched Quad (4) 6973 Electro-Harmonix Vacuum Tubes" is in sale since Thursday, March 22, 2018. This item is in the category "Musical Instruments & Gear\Guitars & Basses\Parts & Accessories\Amplifier Parts". The seller is "onlyglass" and is located in Easthampton, Massachusetts. This item can be shipped worldwide.