Hey Guys,
i'm confused a little, need some clarification to understand the circuit
In attachment is simplified circuit of ccda tube microphone amp used in several chinese microphones (even ribbon ).
Filament and polarisation voltages are ommited.
Circuit was designed for 12AT7 and mostly used with 12AX7.
Based on infromations from the web, i have found that transformer ratio is 4:1 or 5:1 and some people using 10:1 (in original circuit not on fake C12 circuit).
For cathode follower output impedance should be ca. 600ohm for 12AX7, ca. 180ohm for 12AT7.
How the hell microphone output impedance after transformer can be around 200ohm?
What am i missing here?
Any informations, explanations are highly appreciated
i'm confused a little, need some clarification to understand the circuit
In attachment is simplified circuit of ccda tube microphone amp used in several chinese microphones (even ribbon ).
Filament and polarisation voltages are ommited.
Circuit was designed for 12AT7 and mostly used with 12AX7.
Based on infromations from the web, i have found that transformer ratio is 4:1 or 5:1 and some people using 10:1 (in original circuit not on fake C12 circuit).
For cathode follower output impedance should be ca. 600ohm for 12AX7, ca. 180ohm for 12AT7.
How the hell microphone output impedance after transformer can be around 200ohm?
What am i missing here?
Any informations, explanations are highly appreciated