What is the 7868 vacuum tube?

The 7868 is a pentode vacuum tube designed for power (pp) applications. Similar to 7591..

What is a 7868 substitute or equivalent?

Direct equivalents to the 7868 include 7591. These share the same pinout and operating envelope, so they can usually be swapped without circuit changes — though batch-to-batch variations between manufacturers (NOS vs current production) may shift the sonic character noticeably.

What are the key specifications of the 7868?

Transconductance gm ≈ 10.2 mA/V, plate resistance rp ≈ 29.0 kΩ, max plate voltage 550 V, max plate dissipation 19 W, heater 6.3 V / 0.8 A.

Is the 7868 still in production?

Production status varies by year and manufacturer. The current Amperatubes catalog classifies the 7868 as Sought-after availability. NOS (new-old-stock) examples from RCA, Mullard, Tung-Sol, GE, Sylvania and Telefunken trade among collectors; modern production where it exists comes mostly from JJ Electronic, Electro-Harmonix, Tung-Sol (New Sensor), Genalex, and a handful of small-batch makers.

What does the 7868 sound like?

Similar to 7591.. Sonic character also depends heavily on the circuit operating point, the surrounding tubes in the stage, and the output transformer when present — use the interactive loadline calculator on this page to explore the trade-offs.