Hi. I wonder if I should use a led in place of a bypassed cathode resistor. On my ltspice simulation, the led is not lower noise.
So Which one is lower noise ?
Do we have real life noise measuement ?
Can you try to simulate it?
Thank you.
So Which one is lower noise ?
Do we have real life noise measuement ?
Can you try to simulate it?
Thank you.
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merlin blencowe discussed this in his book Designing High-Fidelity Tube preamps p.243
LED is noisier than a bias resistor, but you can bypass the LED with a capacitor to eliminate the noise.
SIC diodes are an alternative to a LED. I add a small resistor to give some feedback. It works with some valves but SIC diodes can sound a bit edgy with others. I haven't tried bypassing them with a capacitor. SIC diodes drop around 0.8v
Are you read this (especially post #233)?
https://www.diyaudio.com/community/threads/some-noise-measurements-for-leds-and-zener-diodes.35821/
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