New Electro-Harmonix KT90 Vacuum Tube

New Plate Current Tested Electro-Harmonix KT90 Vacuum Tubes

This tube has a bit more power than a KT88 but with the classic warm, bass-drenched sound of an EL34. The tube really is the best of both worlds. These are drop-in substitutes for a 6550 or KT88 amplifier but will need some re-biasing.

Testing and/or Matching

At VIVA TUBES, all of our customers get the same high standard of testing and matching. Some sellers charge more for premium matches but we believe all of our customers should get the same level of quality and service. 

Tubes are tested and/or matched at full operating voltage with regulated power supply on a Maxi Matcher tester for general mutual transconductance (Gm). In addition, power tubes are tested/matched by plate current (Ip) and preamp tubes are tested/matched by gain. Rectifier tubes will be tested for emissions on a calibrated military grade tube tester. 

Our goal is to match within 5% with an upper limit of 15% (15% is the industry limit to consider a set).

Hand written test data included.

Note that we do offer a few models which are tested & matched at the factory. They will be matched by the same parameters (Ip & Gm) but to the manufacturer's standards. Factory testing will be indicated in the item title and description. 

Guarantee

We offer a minimum 90 day guarantee covering functional defects - including noise unless otherwise stated. The guarantee period begins the day you receive your order.