5687
Dual Triode · IHT · 9-pin Noval · 1955
“Muscular bass control.”
Medium-gain dual triode for driver and line stage applications
The 5687 is a medium-mu (mu ~18) dual triode originally designed for computer and instrumentation use, built to extreme standards of reliability and vibration resistance. It can handle significantly more plate current than a 6SN7 (up to 30mA per section) while maintaining low distortion, making it an excellent driver tube for demanding loads. The military pedigree means consistent quality and rugged construction, with many examples still testing as new after decades. Tung-Sol and GE are the primary NOS manufacturers; the tube has become a favorite of headphone amplifier designers for its combination of linearity and current drive.