The Electro-Harmonix KT88 is different than the Electro-Harmonix 6550. While the are both great tubes, the KT88 version is modeled after the British sound and has a different internal plate structure. Just like the GEC KT88 this one has a rounded and more bass heavy sound than the 6550. The KT88 and 6550 are electrically equivalent, they just have slightly different sounds.
The new KT88EH tube is here. In this KT88 tube, a new geometry is utilized to reduce odd order harmonics for a sweet top end while the peak power is extended to improve low frequency response.
A new glass formula body ensures long life and improved reliability. The perfect choice when the authentic sound is needed. 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 Octet (8) Electro-Harmonix KT88 Vacuum Tubes" is in sale since Tuesday, January 15, 2019. This item is in the category "Musical Instruments\Guitars & Basses\Parts & Accessories\Amplifier Parts". The seller is "onlyglass" and is located in Easthampton, Massachusetts. This item can be shipped worldwide.