What about KT90? These tubes require .2 to .3 amps more heater current
than KT-88s.
Doubt we could run the new KT120:
Quote:The #1 issue in subbing KT-120s for KT88s is the heater current draw. The nominal spec is 1.9 amps per KT-120 vs. 1.6 amps per KT-88. For a stereo push-pull amp that's a difference of 1.2 amps, and that is beyond the capability of some power trafos.
UNLESS YOU ARE 100% SURE THE POWER TRAFO CAN PROVIDE THE ADDED HEATER CURRENT SAFELY DO NOT USE KT-120s! You may be able to mod your unit to add the juice you need, but don't just plug them in. Even if the trafo seems okay at first, it may cause trouble down the road.
I do not recommend use of the KT-120 in the Citation II amp because of the heater current draw issue - you must add current capability to do it safely.
Quote:"With a plate dissipation of 60 watts, the Tung-Sol KT120 is the most powerful tube in the 6550/KT88/KT90 family. A pair of these tubes in push-pull configuration can deliver power levels of 150 Watts or more. When it's run in circuits designed for 6550/KT88/KT90 tubes, the KT120 resists being overdriven and reliably delivers peak power. (View KT120 spec sheet and curves.)
The KT120 has a taller glass bottle, longer internal plate structure, and much larger control grid cooling fins than current production KT88 tubes. Because the KT120 draws 100-300 mA more filament current than a standard 6550/KT88, check with your amp manufacturer to ensure you have the additional filament headroom to power these tubes. This new production Tung-Sol tube is manufactured in Russia for New Sensor. "