C3m
Pentode · IHT · 8-pin Loctal · 1950
“Predecessor to C3g. Very linear.”
Small-signal pentode for low-noise voltage amplification
GAIN FACTOR0
PLATE IMPEDANCE0kΩ
TRANSCONDUCTANCE0mA/V
GAIN30%
POWER9%
DRIVE98%
LINEARITY85%
EXECUTIVE SUMMARY
The C3m is a indirectly-heated pentode from Siemens·Telefunken, introduced around 1950. It provides a gain factor (μ) of 30 with 2500Ω plate resistance. Commonly used in preamp / driver applications. Predecessor to C3g. Very linear.
APPLICATIONS
Voltage amplifier
Generic pentode preamp / driver stage
• Headphone amp
VS C3g
HISTORY
Introduced1950ManufacturerSiemens·TelefunkenEquivalentsC3g
Golden AgeSPECIFICATIONS
Heater Voltage20V
Heater Current0.125A
Max Plate Voltage250V
Max Power3.5W
Sensitivity12 mA/V
Gain Factor30
Internal Impedance2.5kΩ
Pinout8-pin Loctal
Era1950
RaritySought-after
SPICE model not yet available. Loadline calculator requires calibrated Koren parameters.