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Original Message
RE: Choke or CCS loaded ECC83 in phono stage?
Posted by Paul Joppa on February 6, 2025 at 07:13:13:
For a choke load, you're going to need at least 2000 henries; when Magnequest made one - I believe it was from a Freed design - it was rated >4000H at 1mA. They are now very hard to find.
But a choke will (approximately) double the plate voltage and current, which would call for adjusting the other resistors and capacitors. Plus, any choke not double-mumetal shielded against magnetic fields would likely pick up hum if used in the first stage.
The gain is set by the feedback network, not the stage gains, so current source loads would increase the feedback, not the gain.
The posted circuit appears to have voltages indicated, but the values are illegible so I can't offer much more. And the feedback network is partially cut off, so it's hard to guess the feedback-adjusted gain.