The Tube Amp Doctor KT88-STR is build just like the original tube with its thick curved glass envelope and metal base. The similarities don’t stop with its attractive appearance. This KT88 offers a lively and dynamic tone that is ideal in both HiFi audio amplifiers and high wattage guitar / bass amps. The sound of the TAD KT88 is pleasantly warm at all frequencies with detailed mids, articulate and nuanced highs, and harmonically rich and natural lows. The linear response is excellent. The TAD KT88-STR is matched for both plate current and transconductance and passes all of the tests of the TAD Premium Selection process.