1 low noise tube) 5687 Tungsol rebranded CBS black plates "U" getter NOS 1950's

38ma Gm=12,000

48ma Gm=12,700

Good Ma range 30-35ma

Good Gm = 10,000-12,000

Recommended for

Manley

Modwright

Audio Note

Ray Samuels

Ayon

Kondo

Mastersound

Audio Thrills

Loth